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REVIEW article

Front. Immunol., 07 March 2018
Sec. Vaccines and Molecular Therapeutics
This article is part of the Research Topic Nanoparticle Vaccines Against Infectious Diseases View all 16 articles

Lipid-Based Particles: Versatile Delivery Systems for Mucosal Vaccination against Infection

  • R&D Laboratory, Division of Immunology and Allergy, Centre des Laboratoires d’Epalinges, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland

Vaccination is the process of administering immunogenic formulations in order to induce or harness antigen (Ag)-specific antibody and T cell responses in order to protect against infections. Important successes have been obtained in protecting individuals against many deleterious pathological situations after parenteral vaccination. However, one of the major limitations of the current vaccination strategies is the administration route that may not be optimal for the induction of immunity at the site of pathogen entry, i.e., mucosal surfaces. It is now well documented that immune responses along the genital, respiratory, or gastrointestinal tracts have to be elicited locally to ensure efficient trafficking of effector and memory B and T cells to mucosal tissues. Moreover, needle-free mucosal delivery of vaccines is advantageous in terms of safety, compliance, and ease of administration. However, the quest for mucosal vaccines is challenging due to (1) the fact that Ag sampling has to be performed across the epithelium through a relatively limited number of portals of entry; (2) the deleterious acidic and proteolytic environment of the mucosae that affect the stability, integrity, and retention time of the applied Ags; and (3) the tolerogenic environment of mucosae, which requires the addition of adjuvants to elicit efficient effector immune responses. Until now, only few mucosally applicable vaccine formulations have been developed and successfully tested. In animal models and clinical trials, the use of lipidic structures such as liposomes, virosomes, immune stimulating complexes, gas-filled microbubbles and emulsions has proven efficient for the mucosal delivery of associated Ags and the induction of local and systemic immune reponses. Such particles are suitable for mucosal delivery because they protect the associated payload from degradation and deliver concentrated amounts of Ags via specialized sampling cells (microfold cells) within the mucosal epithelium to underlying antigen-presenting cells. The review aims at summarizing recent development in the field of mucosal vaccination using lipid-based particles. The modularity ensured by tailoring the lipidic design and content of particles, and their known safety as already established in humans, make the continuing appraisal of these vaccine candidates a promising development in the field of targeted mucosal vaccination.

Introduction

Vaccination is considered as one of the most successful medical actions and has greatly contributed to the improvement of world health. Indeed, it has strikingly reduced the prevalence of many infectious diseases, and thus helps nowadays to save millions of lives each year (1, 2). Vaccine administration aims at inducing and harnessing protective effector and memory immunity, comprising neutralizing antibodies (Abs) together with cytotoxic and helper T cells (3) able to control subsequent challenge by the target pathogen. Live-attenuated or killed whole-pathogens have originally been administered for vaccination purposes, but due to safety concerns, including important reactogenicity and risks of reversion, the use of subunit vaccines is preferred. The latter are composed of recombinant or purified pathogen-derived antigenic entities, mostly depleted of innate immune stimulus, that require the co-administration of adjuvants and/or the use of delivery vehicles to achieve sufficient immunogenicity. Over the last decades, important pieces of work in the field of vaccine technology have allowed to rationally design and develop formulations that ensure efficient induction of immune responses (4). Synthetic micro-/nanoparticles, liposomes, immune stimulating complexes (ISCOMs), virosomes, virus-like particles, as well as emulsions, all offer several interesting attributes for vaccine delivery and have already proven efficient in parenteral (intramuscular or subcutaneous) vaccinations by inducing protection against infectious agents (5). These formulations have been designed to mimic biophysical and biochemical features of pathogens, thus ensuring efficient display and delivery of concentrated amounts of antigens (Ags) and adjuvants to innate and adaptive immune cells. Interestingly, this leads to reducing the number of injections required to elicit potent cellular and humoral immune responses with minimal cytotoxicity.

Despite important success in protecting individuals against many deleterious pathological situations, it remains that most of the licensed subunit vaccines are administered parenterally. However, except in previously infected individuals, such a route of administration only induces limited protective effect at the level of mucosal surfaces, the sites where the vast majority of pathogenic agents gain access to the host body (6). In addition to mechanical (epithelium covered with mucus) and chemical (anti-microbial peptides) barriers found at mucosae, adaptive humoral and cellular immunity is of prime importance to efficiently protect against pathogenic insults (7). Thus, to reinforce the efficiency of vaccination, the delivery of vaccine formulations directly to the mucosa represents an asset. It is now well accepted that immune responses have to be elicited locally to ensure efficient imprinting of effector and memory B and T cell homing to mucosal tissues where they will limit entry, colonization, and spreading of pathogens (811). Until now, the few licensed mucosal vaccines consist in administration of live-attenuated or killed whole-pathogens that raise similar safety concerns as for parenteral injection, while no subunit vaccines have been approved for human use. This is mainly due to technical difficulties inherent to the administration route and the physiology of the tissues where the vaccine formulations are applied. Identifying the most adequate vaccine formulation deliverable mucosally remains challenging due to (1) the fact that, in contrast to parenteral vaccination where injected Ags and adjuvants are directly in contact with antigen-presenting cells (APCs), Ag sampling has to be performed across the mucus and the epithelium first; (2) the deleterious acidic, proteolytic, and dynamic environment of the mucosal surfaces which impact the stability, integrity, and retention time of the applied Ags; and (3) the tolerogenic nature of the mucosa, which impairs induction of effector immunity to antigenic entities lacking sufficient immunostimulatory signals (12). Such hurdles may, however, be partially overcome thanks to recent progress made in the understanding of mucosal immunity and in the field of vaccine technology (6).

Apart from immunological and physiological aspects, one important point to be considered for vaccination is the compliance of the patients (13). For pediatric vaccination, administration has to be minimally invasive and easy to perform. The ability of vaccinating a large number of people in countries where endemic infections are present, but where access to medical infrastructures is limited, is of great importance as well. In this context, parenteral vaccination is not the most appropriate strategy as injections are invasive, painful and require trained/skilled medical staff for administration. Moreover, it poses problems related to the risks associated with infection at the site of injection, needle-stick injury, spreading of transmissible diseases, and disposal of used materials. Thus, there is an increasing demand for needle-free vaccination. As an example, mucosal vaccines display several advantages, such as ease of administration and self-delivery allowing mass vaccination, absence of needle-associated risks, and in some cases lower costs and simplified production due to absence of administration devices.

Until now, only few mucosally applicable subunit vaccine formulations have been developed and successfully tested (14), mainly because of the limited number of safe and efficient delivery systems and adjuvants available, coupled to the sometimes important amounts of Ag to be administered. This review will focus on lipid-based micro-/nanoparticles that possess several of the desired characteristics of an interesting Ag-delivery system for vaccination as they are biocompatible, can overcome physiological barriers at mucosae, promote Ag crossing of the epithelium and uptake by APCs, protect the associated payload, are adequate for incorporating adjuvants and may display mucoadhesive properties. In order to achieve the induction of protective anti-pathogen humoral and cellular responses at the relevant mucosal surfaces, the choice of the most potent administration route has to be carefully considered by taking into account the physiological and immunological features of the different target tissues (15). These aspects and the strategies to specifically target vaccines to the portals of entry across the epithelium and increase the efficiency of delivery will first be discussed. However, directing vaccines to the appropriate location is not sufficient to ensure optimal vaccination effect. The architecture, size, and surface chemistry of particles are of prime importance and can be manipulated to influence the intensity and type of immune responses. Physicochemical properties of lipid-based particles, Ag incorporation, mucoadhesion, and association with adjuvants will be discussed next. Examples of mucosal application of such formulations in animal models and their outcome will then be presented. Finally, an overview of the current evaluation of lipid particles and open challenges of mucosal vaccination in humans will be considered.

Vaccine Sampling at Mucosal Surfaces and the Selection of the Route of Administration

When applying a vaccine formulation via any delivery route, the anatomical, functional, and immunological characteristics of the different tissues have to be considered (13). Indeed, the structure and spatial organization of the tissues, the presence of mucus and mechanisms to eliminate deposited materials/particles (e.g., peristaltism in the intestine and physical discharge in the respiratory tract), the pro-tolerogenic environment of mucosae and the presence and localization of particular immune cell subsets, especially dendritic cells (DCs), all impact on the outcome of vaccine administration (16). In addition, safety issues have to be considered. In this section, we will present the characteristics of the mucosal immune system in relationship with vaccination, the different mucosal administration routes, as well as the strategies under evaluation to increase the efficiency of vaccine delivery.

The Mucosal Immune System and Mucosal Vaccination

Mucosal surfaces are continuously exposed to, and challenged by, numerous environmental Ags present, for example, in food, air, or derived from pathogenic or commensal microorganisms in the lumen. On top of the epithelial barrier covered by mucus and the secretion of anti-microbial peptides, a specialized and complex immune network, called mucosa-associated lymphoid tissues, is involved in immunosurveillance of mucosal tissues (17). Lymphoid cells and effector molecules, such as secretory IgA (SIgA), the chief Ab molecule operating at mucosal surfaces (18), cytokines, and chemokines, tightly orchestrate protection against infections and maintenance of tolerance toward endogenous unharmful microorganisms. Sampling for such agents and their delivery to immune cells underneath the epithelial layer takes place via direct uptake by DCs within the epithelium (1921) or across specialized epithelial cells named microfold (M) cells that are responsible for the selective transport of macromolecules, particulate Ags, and microorganisms (22, 23). Internalization via M cells occurs through different mechanisms (clathrin-coated endocytosis, actin-dependent phagocytosis, or macropinocytosis) depending on the nature of the Ags. M cells are present in (a) the follicle-associated epithelium that separates the intestinal lumen (apical side) from underlying immune cells (basolateral side) in Peyer’s patches (PPs), (b) in intestinal isolated lymphoid follicles, (c) in nasopharynx-associated lymphoid tissues (NALT), and (d) in bronchial-associated lymphoid tissues (BALT) (24). Such structures are composed of innate and adaptive immune cells, including functionally different DC subsets, T, and B cells. DCs integrate signals derived from the sensing of the luminal environment, and release soluble factors, such as cytokines and chemokines, to orchestrate the generation of tightly controlled mucosal immunity locally or after migration in regional lymph nodes (LNs) (7). In addition, paracellular and transcellular uptake of macromolecules and small particles across the epithelia lead to their uptake by APCs outside inductive sites for induction of local immunity via regional LNs. By contrast, in the urogenital tract and in the oral cavity, the stratified epithelium does not contain M cells and sampling occurs by DCs interspersed within the tissue leading to induction of immune responses exclusively in draining LNs (15, 25, 26).

Upon encounter with microorganisms or vaccine formulations, mucosal DCs in combination with neighboring epithelial cells control the expression of specific homing receptors on primed lymphoid cells and modulate the type of ensuing immune response (8, 9, 27). Such imprinting relies on the expression of site-specific integrins and chemokine receptors by B and T cells and allows their transit via the lymph and through the blood to migrate to different mucosal sites. Recirculation of lymphocytes to the gut requires expression of α4β7 and CCR9, whereas migration to the airways, the oral cavity, and the reproductive tract relies on L-selectin and CCR10. In the case of pathogenic infections, danger signals generated by the sensing of microorganisms switch immune responses toward an effector type of response relying on both humoral and cellular arms to eliminate the infection (28). Immune exclusion and neutralization by SIgA, as well as production of Th1- or Th17-type cytokines that activate phagocytes and induction of cytotoxic T cells, all contribute to the protection of mucosal surfaces (29, 30). Therefore, the major aim of vaccines would be to elicit specific B and T cell responses at the relevant sites to induce specific SIgA that provide a first line of protection against invading pathogens, together with appropriate cellular immune responses to eliminate both the pathogen and pathogen-infected cells. For example, requirements for proper B cell isotype-switching and the generation of IgA responses include mainly the production of TGF-β, IL-6, retinoic acid, and IL-21 by PPs’ cells, together with the CD40–CD40L interaction between T follicular helper cells and B cells (31). Thus, vaccine formulations for mucosal application have to be designed to best induce such immunological environment.

Administration Routes for Mucosal Vaccination

Each route of mucosal administration has its own characteristics and a balance between the pros and cons for each vaccine has to be considered, taking into account the pathogen to fight against and the formulation to be delivered. However, no standardized studies are available to directly compare safety, profile of induced immune responses, and efficiency of protection. In this section, we will consider the different mucosal administration routes. Oral and nasal/pulmonary are the most studied ones, but sublingual is now recognized as a promising way of vaccination. Vaginal and rectal delivery have also been studied, but more scarcely. Even though the most powerful response is usually elicited in the local inductive and adjacent tissues, the common mucosal immune system predicts that homing to distant mucosal tissues is possible (27). However, a certain degree of compartimentalization does not allow imprinted cells to migrate to every mucosal sites. Such flexibility allows to select for the most appropriate route of vaccination to induce protective immune responses at the desired site. Of note, some recent works demonstrated that transcutaneous immunizations have the potency to promote the induction of immune responses with the ability to traffic to the gut and airways, although up to now with low consistency (32). However, this aspect will not be covered by this review and has been described elsewhere (33, 34).

Nasal administration represents a promising route for mucosal vaccination (35), because nasal tissues display a relatively large surface for Ag absorption covered with only a thin layer of mucus, and are highly vascularized. It does not require the delivery of high Ag doses (e.g., as compared to oral administration), is non-invasive and easily accessible for self-administration. Nasal vaccination allows the generation of a broad range of Ab and T cell responses at different mucosal sites, such as the upper (preferentially) and lower airway mucosae, the local secretions, the salivary glands, and the urogenital tract. It also elicits concomitant robust systemic immunity (15). However, in the nasal environment, the presence of proteases and the local pH, together with a relatively high mucoscillary clearance rate, may impact on the vaccine integrity and retention time, thus affecting the generation of immune responses. The major drawback concerns the safety of nasal administration, as physiological function such as smell perception might be altered by vaccine-induced inflammation and the close relationship with the brain might promote health problems. Thus, every vaccine candidate has to be evaluated carefully for safety. Sometimes achieved by nasal delivery or directly targeted, pulmonary immunization allows vaccine formulation to directly access the respiratory tract which is of interest due to its high permeability, its large surface area and the high density of APCs (alveolar macrophages, DCs, and B cells). This route of administration preferentially induces immune responses in the lower airways and has interestingly been shown to promote cellular and humoral responses in the gut. However, efficient delivery in the lung is not an easy task. Delivery via the nasal and pulmonary routes does not necessarily lead to similar outcomes: for example, pulmonary vaccination was shown to be more effective than its nasal counterpart at protecting against Mycobacterium tuberculosis infection, because different immune mechanisms were involved after one or the other administration route (3638). Indeed, elevated levels of SIgA were produced in the lung after pulmonary vaccination, with equivalent responses observed in the nasal passage. In addition, IFN-γ production in the lung following pulmonary vaccination was important to fight against M. tuberculosis, whereas there was apparently no role for this cytokine in the nasal environment.

Oral administration represents an interesting strategy in terms of ease of delivery, patient compliance, and safety (39). However, due to the intrinsic high dilution of vaccine formulations and the harsh environment of the digestive tract, substantial amounts of Ags have to be administered. Indeed, the extremely low pH in the stomach, proteolytic enzymes and bile salts in the intestine, the presence of relatively thick one-layered mucus, and the overall low permeability of the intestine greatly affect the integrity and delivery of applied Ags. In this context, oral vaccines are likely to be more efficient if repeated doses are given, provided that adjuvants are incorporated to avoid tolerance induction (13). Oral administration is the most efficient delivery route to achieve induction of gut immunity, which is of high importance to fight against the large burden of enteropathogenic infections worldwide. Induction of immune responses in the colon, stomach, mammary, and salivary glands, as well as systemically, also takes place, but with limited robustness (15).

Sublingual immunization generates immune responses with similar profile and mucosal tropism as nasal delivery, i.e., vigorous and broadly disseminating mucosal and systemic IgA and IgG, as well as helper and cytotoxic T cell, responses (40), without many side effects (41), and formulation concerns associated with nasal or oral immunization (42). It is also easily accessible for self-administration. It has been shown to induce immune responses after administration of soluble Ags, particulate Ags, live/killed bacteria, and viruses (40). Sublingual delivery is interesting because the oral cavity has a milder environment that may not degrade vaccine components, and may, thus, not require large amounts of Ags. As an example, higher Ab responses were obtained in mice after sublingual, as compared to oral, administration with about 10–50 times less Ag applied (43). One limiting factor is the absence of Ag-sampling M cells in the oral cavity lined by a stratified epithelium and the relatively low number of DCs in the upper layer of oral tissues. However, vaccine formulations can be taken up by lingual tonsils for delivery into regional LNs and Langerhans cells in the oral epithelium have been shown to act as potent inducers of immunity (15). Several delivery systems (microneedles, liposomes, inactivated microorganisms) and adjuvants [toll-like receptor (TLR) ligands, cholera toxin (CT), mutants of heat labile toxin (LT) and CT] have been evaluated for sublingual vaccination and protective Th1-type responses in the lung, genital tract, and the gut, together with SIgA in the saliva, intestinal, and vaginal washes, have been obtained with different vaccine formulations (4245).

Vaginal immunization elicits immune responses in the genital tissues and secretions, but is not efficient to induce systemic immunity. Despite relatively low pH, the vagina is a mild environment that does not impair Ag integrity and, thus, allows to limit the amount of Ag to be delivered (25). However, the presence of a stratified epithelium and the absence of inductive sites imply that induction of vaccine response via vaginal delivery requires specific adjuvanted formulations and DC subsets (46). In addition, the changes occurring in term of immunological functions during the estrous cycle complicate such immunization (4749). Additional studies are required to better understand mucosal immunity in the urogenital tract and define specific requirements for vaccine formulations. Rectal immunization is able to induce potent immune responses in the small intestine and the colon, but not efficiently in the systemic compartment (15). Only limited studies are available to fully appreciate the potential of such an administration route for mucosal vaccination.

Targeted Delivery of Vaccine Ags

Not only do vaccine formulations have to resist the deleterious environment of some mucosal surfaces, but they also have to face an additional hurdle that is to cross the epithelium to gain access to underlying APCs. In this context, targeting the relatively low number of portals of entry at inducing sites, e.g., M cells that represent 1% of epithelial cells (5–10% of enterocytes within the follicular-associated epithelium), or DCs spread within the epithelium is an asset for efficient vaccination. DC targeting by the mean of C-type lectin receptors (DEC205, DC-SIGN, mannose receptor) or specific Abs directed against DC markers has proven to be an efficient strategy to improve the potency of parenteral vaccination (50). Similar strategies have been developed for mucosal vaccination, such as targeting of Langerin on DCs of the oral cavity, the esophagus or the vaginal mucosa (51). FcRn expressed by airway and gut epithelial cells (52, 53), as well as some DC subsets (54), has also been demonstrated as an efficient strategy to deliver IgG-based complexes across the epithelium and to underlying DCs. Such an approach efficiently led to the induction of both CD4 and CD8 T cell effector responses (5557). Galactosyl ceramide may function as a targeting moiety in the intestine, the rectum, and the endocervical mucosa (58), and the ganglioside GM1 molecule can be targeted by a specific peptide developed by phage display (59). As far as M cells are concerned, specific delivery can be achieved via different strategies: the tight junction molecule claudin-4 (60), the bacterial FimH receptor GlycoProtein-2 (61, 62), the complement C5a receptor and its ligand Co1 (63, 64), a M-cell-specific peptide referred to as CKS9 (65), or the unique glycosylation pattern involving α-1-fucose; for the later, the use of Ulex Europaeus Lectin-1, or a specific monoclonal Ab have been successfully demonstrated (6668). However, in humans, the lack of expression of this particular sugar moiety on M cells (69), together with the extra-M cell expression of GP-2 (70), precludes the use of such strategies for specific targeting purposes. By contrast, a promising approach consists in coupling vaccine Ags with SIgA in order to induce M-cell-specific retrotransport across the epithelium and DC targeting via Dectin-1 in both mice and humans (71). This Ab molecule can potentially serve as a cargo for the controlled delivery of the associated payload as this occurs naturally with microorganisms sampled from the mucosal lumen (72). An additional advantage is the resistance of SIgA to protease degradation and its ability to anchor in mucus (18), two features that may improve both stability and retention time of the associated Ags.

Formulation Considerations

Particulated Ags have been designed to mimic the shape, size, and antigenic display of pathogens with the aim of improving vaccine efficiency (73). Ags associated with micro-/nanoparticles display increased depot effect upon administration, are better protected from degradation, and are more efficiently taken up by APCs and presented to B and T cells than soluble Ags (74). An important number of studies have evaluated the effect of particle properties (type of material, size and charge, Ag incorporation, or association of adjuvants) on the profile and strength of induced Ab and T cell responses. When composed of natural lipids, lipid-based particles have the advantage of being biocompatible. In addition, they are very flexible in terms of formulation, implying that lipid exchange within the particle shell is achievable, leading to modulation of their physico-chemical properties. This is of importance in the biological environment because all these parameters will influence the stability and immunological consequence of delivered particles. However, minor changes in the composition of the particle may impact on its efficiency and protective ability, meaning that any formulation needs to be individually evaluated in vivo.

Size and Charge of Particles

The size of particulate Ags has an impact on the type of immune responses that are generated because it influences the mechanism of uptake by APCs. Indeed, receptor-mediated endocytosis, pinocytosis, macropinocytosis, or phagocytosis, all lead to different ways of trafficking within the cells and, therefore, induce preferentially presentation via the MHC I or MHC II pathway for CD8 or CD4 T cell priming, respectively (75). Small particles (up to 200 nm) are sensed as viruses and are taken up by receptor-mediated endocytosis leading to predominant T cell responses, whereas larger particles (more than 500 nm) are taken up via micropinocytosis or phagocytosis to preferentially induce Ab responses (76). Similar size-dependent uptake by M cells or enterocytes takes place, leading to differential sampling of the particulated Ags. Other studies demonstrated that vesicles smaller than 250 nm induced a balance toward Th2-type of responses, whereas the opposite was observed for larger vesicles (7779). Moreover, in the context of mucosal delivery, the size of the particles influences the tissue localization and the diffusion across the mucus. Following nasal administration, small particles are better transported across the nasal mucosa, whereas larger ones are better deposited in the respiratory tract to be taken up by alveolar macrophages (80, 81). In order to get access to the epithelium, both viscosity and pore size of mucus can impact on the penetration of vaccine components. Apparently, the average size of pores in the mucus is in between 200 and 500 nm, e.g., in the cervicovaginal and small intestinal mucus. This suggests that particles smaller than this cutoff freely diffuse across the mucus, whereas larger ones take more time to reach the epithelium or possibly never reach it (82, 83). One major point to be considered is that correlation between size and immunogenicity is difficult to strictly assess for lipid-based particles, because homogeneous and monodispersed preparations have been challenging to obtain, and when feasible, such preparations require technical issues that may dramatically increase the cost of vaccine formulations.

Diffusion across the mucus is not only governed by size of particulated Ags or mucus pores but also by chemical characteristics such as the surface charge of particles. Hydrophobic and electrostatic interactions mediated by particles aggregate mucus microstructure and impede diffusion of vaccines, while hydrophilic and neutral vaccine formulations promote mucus penetration (23). Mucoadhesion is promoted by positively charged particles that interact with negatively charged mucus. For example, electrostatic interactions between cationic lipids and the nasal mucosa promote enhanced contact time with the tissue, higher local concentration, and thus improved penetration of liposomes (84). Similarly, cationic particles better interact with negatively charged cell membranes, such as those of M cells and enterocytes, therefore limiting vaccine clearance and improving sampling via endocytosis or membrane fusion (85, 86); it also improves the uptake by DCs (87). However, cationic particles may have charge-dependent cytotoxicity against target cells; therefore, the density of cationic lipids within the particle shell has to be carefully defined and a tight balance between strong adhesion and safety has to be achieved (23). Interestingly, it seems that the presence of the mucus limits cytotoxicity (85), meaning that cationic particles keep their validity for mucosal vaccination.

Incorporation of Ag

There are different ways of associating Ags to lipid-based delivery systems and the choice depends mainly on the administration route and the nature of the Ags (88, 89). For oral administration, encapsulation seems favorable in terms of ensuing immune responses, because it prevents rapid degradation of the Ag within the gastrointestinal environment and, hence, increases its half-life (90). Encapsulation of Ags is relatively easy to perform during the manufacture process, but this may alter antigenic structures. By contrast, maintenance of the integrity of the Ags is less affected by the nasal route, suggesting that surface association via charge interaction is sufficient. Such an approach is technically not demanding, owing that opposite charges of either the particles or the Ags favors it (90). Alternatively, covalent binding at the surface of particles is achievable, although more complicated to perform; this precludes the undesired release of the payload that may occur within the tissue environment. In terms of immune response induction, encapsulation within liposomes preferentially induces IgG production, whereas surface display of the Ag induces both IgM and IgG responses (91), with elevated levels (92). In addition, Ag density at the surface of particles, as well as the Ag-to-lipid ratio, has been documented to influence the elicited immune responses following immunization (93, 94). This may suggest that both encapsulation and surface location of the Ag within the same formulation would promote optimal induction of T cell and B cell responses.

Apart from protein Ags, plasmid DNA coding for pathogen-derived Ags have been evaluated for vaccination (95, 96). Such strategy has an established record of efficacy in preclinical studies and can be safely used in humans, even in immunocompromised individuals. However, based on results obtained in the field of veterinary vaccination, naked DNA induces only weak immune responses. In order to improve immunogenicity, association of DNA with cationic liposomes leads to increased uptake by target cells and delivery into the nucleus. DNA immunization through the nasal or the oral route can effectively induce protective humoral and cellular immunity at related mucosal surfaces, but necessitates association with cationic delivery systems, presumably to increase mucus penetration, to reduce mucociliary clearance, and to improve permeation across the epithelium (97, 98). DNA sequences such as the canonical CpG motifs have been shown to display immunostimulatory properties. In a similar way, messenger RNA-based vaccines, when approprietely protected from ribonucleases are translated in the cytoplasm and do not require nuclear transport (99). This has been mainly evaluated with cationic lipid-based vesicles in the context of cancer immunotherapy, and the efficient nasal application of particle-associated mRNA has been demonstrated (100).

Mucoadhesive Properties

Upon mucosal administration, vaccine formulations are diluted in mucosal fluids and have to face bulk flow, leading to limited retention time and suboptimal access to the epithelium for sampling. Such deleterious effects can be compensated by incorporation of mucoadhesive and mucus-penetrating components. In this case, the surface structure of lipid-based particles has to be carefully designed to obtain an adequate balance between strong adhesion and mucus penetration. Some possible strategies are described below. The first one consists in incorporating polyethylene glycol (PEG) at the surface of particles. PEG has originally been used for systemic administration in order to avoid adsorption of plasma proteins and the formation of a corona that may mask targeting ligands, adjuvants, or Ags at the surface of particles (101). In addition, the presence of PEG increases the stability upon administration. A similar stabilization effect has been reported in the case of oral or sublingual delivery of liposomes (93, 102, 103). PEG is a hydrophilic component that has been reported to help particles to penetrate the nasal mucosa by preventing aggregation and thus facilitating diffusion across the mucosal barrier. Moreover, it can form hydrogen bonds with mucus leading to mucoadhesion, but also helps diffusion across the mucus; indeed, such intriguing bifunctionality has been correlated with the molecular weight of PEG. High molecular weight polymers (>PEG5000) are preferentially mucoadhesive whereas lower ones (PEG2000) better diffuse within the mucus (103105). An additional non-negligible advantage of PEG is that it provides cryopreservative functions during particle manufacture.

The second strategy is to associate with micro-/nanoparticles some mucoadhesive components, such as chitosan (deacetylated chitin), alginate, polyvinyl alcohol, hyaluronan, or cellulose derivatives that all boost particle-based vaccination (106108). Addition of bioadhesive components (xanthan gum or tramella) within formulations helps to increase the viscosity of the vaccine and, thus, the retention time at mucosal surfaces. The most studied mucoadhesive molecule is chitosan, whose relevant properties for mucosal vaccination are as follows: (1) it is a positively charged molecule that can interact with negatively charged mucus to improve adhesion; (2) it is a permeation enhancer due to its ability to transiently open epithelial tight junctions and, thus, improve Ag sampling (109); and (3) it has adjuvant properties, promoting induction of IFN-γ, IgG, and SIgA (110). Chitosan has been explored for delivery via oral, nasal, and pulmonary routes in association with liposomes leading to increased stability and mucoadhesion for absorption by mucosal surfaces (111). Interestingly, it did not demonstrate detrimental effects toward mucosal tissues (112).

Incorporation of Adjuvants

Several adjuvants have been evaluated during the last decades for mucosal vaccination (113). Essential properties of the ideal adjuvant include the following: to be effective with low-dose Ag; to be suitable with many different Ags; to be effective enough to reduce the number of vaccine administrations; to be able to induce long-term immune responses; and to display limited or absent toxicity. Innate immune triggers have been used as adjuvants as they have the capacity to elicit pro-inflammatory responses to recruit phagocytes, to enhance Ag presentation by APCs, and to activate APCs in order to generate the adequate environment for efficient priming of adaptive immunity. Studies in animals have demonstrated an important adjuvant effect of the Vibrio cholerae endotoxin CT and Escherichia coli LT, ensuring enhanced Ag permeation through the epithelium, enhanced targeting of M cells, increased Ag presentation by DCs and improved activation of DCs (114); a direct effect on B and T cells has additionally been reported (15). However, such adjuvants are inadequate for human use because of their toxicity and unacceptable side effects, as for example: induction of deleterious inflammatory response leading to altered function of olfactory nerves or to Bell’s palsy after nasal administration, and diarrhea symptoms after oral administration (115, 116). This has oriented research toward the generation of less toxic derivatives engineered by introduction of mutations in the A subunit of CT and LT (117120). The most promising derivative is the double mutant LT (R192G/L211A, dmLT) that has no demonstrated side effects in animal application while retaining important adjuvant activity after oral or sublingual administration (121123). Similar mutations R192G/L211A applied to CT similarly reduced its toxicity, although to a level still not acceptable for human use. Introduction of additional mutations within the amino acid 189–197 stretch recently demonstrated more safety with an ability to induce both Ab and T cell responses close to that of the non-mutated CT following nasal, oral, and sublingual vaccinations (124). An alternative approach is the use of the B subunit of LT or CT only. LTB and CTB are not very efficient via the oral route, however, nasal administration demonstrated some efficiency when the Ag was physically linked to the adjuvant resulting in increased uptake across the epithelium and by DCs (15). Fusion protein obtained by association of the A1 subunit of CT and S. aureus protein A derivative (CTA1-DD) proved efficient at boosting B cell responses after nasal administration (125). In another report, edema toxin from Bacillus anthracis and diphtheria toxoid within lipidic particles have been evaluated for nasal administration and showed efficient induction of immune responses leading to reduced bacterial load after pathogen challenge (126).

In parallel, evaluation of immunostimulatory molecules active for parenteral administration, such as TLR ligands, have been performed (113). CpG oligodeoxynucleotides (CpG), monophosphoryl lipid A (MPLA), and flagellin that are ligands for TLR-9, TLR-4, and TLR-5, respectively, have been administered orally or intranasally and demonstrated immunostimulatory properties for mucosal immune responses, including induction of SIgA (127131). Pulmonary delivery of a M. tuberculosis-derived Ag together with CpG or MPLA promoted the generation of IFN-γ production in the lung; MPLA was more potent to induce IL-17 production and to decrease the bacterial load following challenge (132). Flagellin, expressed by different pathogenic bacteria, can indirectly stimulate local DCs following nasal delivery, and induce mucosal IgA responses and protection upon Influenza vaccine administration (133, 134). Alternatively, trehalose dibehenate (TDB), a synthetic analog of a M. tuberculosis cord factor known to interact with Mincle and promote Th1/Th17-type of responses (135), has also been shown to be effective by the nasal route (136). Saponin QS21 also demonstrated potent adjuvant effect when nasally administered (128, 129). In addition, STING ligands 3′3′-cGAMP, c-di-AMP, and c-di-GMP have been efficiently delivered via the nasal or the sublingual route to elicit Th1/Th17 responses and high-affinity SIgA (137). Activation of NKT cells by administration of α-galactosylceramide is also of interest for nasal, oral, and sublingual vaccination due to its ability to enhance immunogenicity of different mucosal vaccine formulations (138140). All these adjuvants can be incorporated within lipid-based particles or associated at their surface depending on the localization of their cognate receptor in target cells. This has been successfully achieved and resulted in improved uptake by and activation of DCs (141). Moreover, cationic lipids per se have been shown to directly activate APCs (142).

Lipid-Based Particles for Mucosal Vaccination

In order to induce efficient and protective immune responses by vaccination, not only the Ags and the adjuvants have to be carefully defined, but also an appropriate delivery system is of prime importance. When aiming at using mucosal routes of administration, they must be designed to resist chemical degradation by low pH, proteolytic enzymes, and the harsh environment of mucosal surfaces. Lipid-based particles represent interesting delivery systems to incorporate Ags and adjuvants, allowing targeted and concentrated delivery of relatively low amounts in tissues, together with limiting toxicity associated with potential spreading of the payload (Figure 1). Many lipid-based particles have been tested in animal models of immunization and/or infection and are reviewed below (Table 1). Advantages, limitations, and necessary refinements for use as effective mucosal vaccine are discussed sequentially.

FIGURE 1
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Figure 1. Schematic representation of lipid-based particles evaluated for mucosal vaccination. Liposomes can be tailored to incorporate particular lipids (cationic lipids, polar lipids from Archea), Influenza extracts or non-ionic surfactants in order to improve stability and immunogenicity of vesicles. Other lipid-based structure incorporating saponin, entrapping inert high molecular gas, or composed of emulsions has been developed for vaccination purposes. Black triangles represent Ags. They can be entrapped in aqueous cores, entrapped in hybrophobic parts, associated at the surface of particles through electrostatic interactions, or covalently linked at the surface of particles. Not drawn on scale.

TABLE 1
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Table 1. Lipid-based formulations evaluated for mucosal vaccination in mouse models.

Liposomes

The enormous potential of liposomes for drug delivery has been acknowledged for decades. Indeed, they display features including controlled release, protection from degradation, improved pharmacokinetics, increased circulation time, and targeting to specific tissues (143, 144). They have been progressively adapted for administration of diverse antigenic entities, such as proteins, peptides, and DNA, in order to produce vaccine formulations to fight against several viral and bacterial infections (89). Liposomes are spherical vesicles consisting in unilamellar or multilamellar shell of phospholipid bilayer(s) entrapping an aqueous core and range in size from tens of nanometers to several micrometers in diameter. The amphiphilic nature of phospholipids mediates self-assembling of liposomes in an aqueous environment leading to a bilayer configuration. They can incorporate both hydrophilic molecules encapsulated within the aqueous core and hydrophobic molecules hooked at their surface or inserted within the inner hydrophobic space of the lipid bilayer. Biocompatible neutral and anionic phospholipids, such as phosphatidyl cholines [e.g., distearoylphosphatidylcholine (DSPC)], and cholesterol, are the most commonly used constituents of the shell that ensures proper stability of the structure and improved immunogenicity of the formulation (145, 146). The length and degree of saturation of acyl chains influence both the permeability and the fluidity of the shell, leading to increased or decreased stability. Liposomes are versatile delivery systems that are interesting for vaccination formulations because their physicochemical properties can be modulated by altering their composition in lipids. Among possible modifications, pH titrable lipids to induce controlled release of payloads (147, 148) and synthetic cationic lipids to improve immunogenicity (90) have been generated. In addition, functionalization of liposomes with specific targeting moieties has emerged as a promising strategy to improve delivery. Vesicles bearing the DC-SIGN-specific ligand Lewis x glycan showed increased DC-targeting properties and subsequent activation of T cells, especially when adjuvanted (141) and IgG-coupled liposomes have demonstrated enhanced transmucosal transport in nasal tissues (55).

Cationic liposomes prepared with dioleoyltrimethylammoniumpropane (DOTAP), dimethyldioctadecylammonium bromide (DDA), dimethylaminoethane-carbamoyl (DC)-cholesterol have been successfully evaluated. Nasal administration of DDA-based liposomes induced greater local and vaginal IgA production as compared to vesicles without cationic lipid. Moreover, the incorporation of PEG further increased the observed immune responses (149). Similarly, delivery of cationic liposomes composed of DOTAP and DC-cholesterol via the nasal route allowed efficient uptake by DCs in NALT and subsequent induction of specific IgA and T cells in nasal tissues (150). The adjuvant CAF01 is a prime example of efficient cationic liposomes to be used for mucosal vaccination. Incorporation of both DDA and the immunostimulatory molecule TDB, has been evaluated in several animal models of infections with Influenza, Chlamydia and M. tuberculosis (151). In such context, the presence of the adjuvant had a substantial beneficial effect on immunogenicity (152). Nasal vaccination against Influenza or Streptococcus pyogenes with CAF01-based formulations allowed to generate mucosal effector T cell and IgA responses and to protect vaccinated animals (136, 153). Furthermore, preparation of liposomes with the cationic lipid ceramide carbamoylspermine efficiently stimulated systemic and mucosal immunity following intranasal administration (154). The use of cationic preparations is also an interesting approach for alternative forms of antigenic entities, as liposomes incorporating DOTAP and a plasmid DNA coding for a mycobacterial heat-shock protein given nasally induced local mucosal immune responses able to reduce M. tuberculosis load in the lung (155). Overall, liposome-based vaccination via the nasal route leads to the induction of robust immune responses whatever the nature of the Ag and its mode of incorporation. Thus, fine-tuning modulation of the profile of vaccine-elicited responses appears to depend on the composition of the formulation, including the type of lipids and/or the presence of adjuvants. Interestingly, most liposomal preparations seem to be well tolerated, inducing only limited inflammatory responses, irritation, sneezing, or burning syndroms. Oral administration of liposomes has been documented, but its stability in the gastrointestinal tract remains the main concern. As already discussed in Section “Mucoadhesive Properties,” promising approaches can be envisaged to improve the stability of liposomal preparations. Incorporation of mannose, chitosan, and PEG are all possible scenarios resulting in reinforced stability, better targeted delivery across the epithelium and to APCs, and improved immunogenicity. Stabilization of liposomes with layer-by-layer deposition of polyelectrolytes also increased the generation of Ab and T cell responses in mucosal tissues (156). The administration of multilamellar preparations is an alternative strategy. Finally, as discussed in Section “Administration Routes for Mucosal Vaccination,” vaccination via the sublingual route is a promising development that requires to be further evaluated for liposomal preparations in the context of infectious diseases. For example, PEG-modified liposomes incorporating Influenza-derived Ags, together with the TLR-4 agonist CRX-601 as adjuvant, were effective at eliciting elevated levels of serum neutralizing Abs and mucosal IgA (103).

Liposome-Derivatives

Derivatives of liposomes have been explored to circumvent some of the drawbacks associated with liposomes and to improve their efficiency. For example, association of non-ionic surfactants with cholesterol or its derivatives to generate a structure called niosomes has allowed to increase the stability of the bilayer vesicles by preventing oxidation of the lipids (157). Addition of mannan at the surface of niosomes further increased the stability of the vesicles and helped to target specific receptors on APCs following oral administration. Vaccination with niosomes incorporating plasmid DNA coding for an Hepatitis B Ag induced SIgA production in the salivary and intestinal fluids, together with systemic Th1-type T cell responses (158). Moreover, incorporation of bile salts within niosome structures (bilosomes) has been shown to increase the stability of the vesicles and thus to improve oral delivery of peptides and proteins to the gut immune system (159, 160). Bile salts, such as deoxycholic acid or taurocholic acid, are amphiphatic molecules that can be easily incorporated within lipid bilayers and can promote the passage of lipophilic components across cell membranes (161). Thus, bilosomes have the ability to reinforce the biovailability of associated Ags mainly for oral vaccination (162). Different examples of bilosome application have been reported in association with Hepatitis B-derived Ags and Tetanus toxoid. In this context, induction of SIgA in mucosal secretions and IgA-positive plasma cells were observed (162164) and showed elevated responses as compared to parenteral injection or use of niosomes without bile salts. An alternative approach is the inclusion of polar lipids with fully saturated isoprenoid chains extracted from Archaea to generate vesicles called archaeosomes or archaeal lipid mucosal vaccine adjuvant and delivery (AMVAD) (165). They have been shown to induce robust long-lasting protective Ab and T cell responses, including cytotoxic T lymphocytes responses after systemic injection (166). Advantages of such structures for mucosal vaccination comprise increased pH-dependent and thermal stability due to prevention of lipid oxidation and resistance to phospholipases and bile salts. In this context, mice immunized by the nasal route demonstrated sustained robust local and distant IgA responses in mucosal fluids, strong systemic IgG responses, and T cell responses (167). In addition, nasal vaccination with archaeosomes and cell-free extracts of Francisella tularensis led to reduced bacterial burden in the lung and spleen in a mouse model of tularemia (168). Oral immunization with archaeosomes is possible as well, although with higher amounts of Ags. Improved stability and retention time of such vesicles has been observed in the intestine, leading to potent IgG and IgA production (169). One non-negligible drawback of this approach is the access to achaeal polar lipids, as the purification from Archaea is a relatively demanding process. Nevertheless, production of synthetic polar lipid structures is under development.

Virosomes

Virosomes are a special category of liposomes, where part of the lipid content is derived from viral components that self-assemble into an organized three-dimensional structure that mimics the antigenic structure of the original virus (170). Interestingly, they have been demonstrated to be immunogenic without further addition of adjuvants (171), although addition of immunopotentiating agents further improves their vaccine efficiency (172). Originally called immunopotentiating reconstituted Influenza virosomes, they harbor hemagglutinin and neuraminidase proteins from Influenza virus. These proteins target sialic acid on cell membranes, leading to fusion between the target cell and virosomes, followed by intracellular delivery of their payload. They exhibit similar flexibility and advantages as standard liposomes; however, the process to extract all the necessary components from Influenza virus is relatively complex. Virosomes have been mainly investigated for parenteral vaccination, but reports on their use for mucosal administration exist. They have been used as prime-boost vaccination strategy in a simian model of HIV infection, where intramuscular injections have been followed by nasal administration. It induced full protection against vaginal simian-HIV challenge that was correlated with the presence of mucosal IgA and IgG with blocking activity against virus transcytosis and neutralizing/Ab-dependent cellular cytotoxicity properties, respectively (173). In mice, nasal or sublingual administrations of adjuvanted virosomes were able to protect against Influenza and respiratory syncytial virus infections by promoting mucosal and systemic Ab responses, together with Th1-type cellular responses (174176).

Gas-Filled Microbubbles

Gas-filled microbubbles are microsized spherical structures composed of a lipidic, denatured protein-based, or crosslinked polymer shell generally entrapping inert high molecular weight gases to ensure resistance to pressure once administered (177). Due to their strong echogenicity in presence of low ultrasound intensities, they are currently used for human application as intravenously delivered echo-contrast agents to more precisely visualize for example angiogenesis in malignant tumors, left ventricular opacification, and myocardial perfusion. In addition, cavitation induced by higher ultrasound application leads to the transient nonlethal permeability of the surrounding tissue (e.g., vascular barriers or cell membrane) allowing enhanced local on-demand extravasation and bioavailabilty of microbubble-associated payload (178). In the last decades, such a process, known as sonoporation, has received important attention in order to improve delivery of a wide range of therapeutic molecules, including chemotherapeutic agents, siRNA, miRNA, oligonucleotides, or plasmid DNA, to tumor or immune cells (177, 179). Typically, sonoporation has been used for improved delivery of Ags into DCs with the aim of boosting immune responses (180). Interestingly, lipid-based microbubbles can be taken up by APCs and deliver intracellularly their antigenic payload without ultrasound application, leading to processing and presentation of the Ag to responsive T cells (181, 182). Furthermore, microbubble-associated Ags can be injected parenterally as a vaccine formulation to elicit potent and long-lasting immune responses against systemic bacterial infection (183, 184). Lipid-based microbubbles are usually composed of phospholipids (e.g., DSPC) and palmitic acid, but tailored formulations can be prepared by incorporation of cationic lipids in their shell in order to better associate DNA (179). In addition, to improve the specificity of imaging and drug delivery, microbubbles can be targeted to particular tissues by linking cell-specific ligands or Abs has been developed at their surface (185, 186). Such aspects are of interest for mucosal vaccination using targeting strategies as discussed in Section “Targeted Delivery of Vaccine Ags.” Moreover, adjuvants can be associated with microbubbles, which results in enhanced immunogenicity of the vaccine preparations. As an example, nasal delivery of α-galactosylceramide-adjuvanted microbubbles displaying the Salmonella-derived SseB Ag at their surface were able to induce potent IgA, IgM, and IgG humoral responses in the gut, which were associated with a Th1-/Th17-type cellular response. This resulted in a significant decrease in local and systemic bacterial load following oral infection with Salmonella enterica Typhimurium in prophylactically vaccinated mice; such effect was more potent than parenteral injection of the same microbubble formulation (140). Despite so far limited induction of local immune responses after oral administration, improvement of microbubble formulations may lead to enhanced immunogenicity. Moreover, sublingual administration remains to be tested owing to its valuable advantages in the context of mucosal vaccination. In recent years, nanosized bubbles have been developed that showed increased stability and extravasation following systemic administration, suggesting that such derivatives might be even more suitable for vaccination purposes (187).

Immune Stimulating Complexes

Immune stimulating complexes (ISCOMs) are negatively charged self-assembling pentagonal dodecahedrons cage-like rigid structures with a size of 30–40 nm. They can form spontaneously after mixing Ags with cholesterol, phospholipids (usually phosphatidylethanolamine and phosphatidylcholine), and the saponin Quil A extracted from the bark of Quillaja saponaria Molina tree. Interestingly, such formulation allows to reduce the toxicity associated with saponin administration, while retaining its adjuvant activity (188, 189). Proteins or glycoproteins that are normally anchored by a hydrophobic transmembrane sequence into the cell membrane can be incorporated as such. Non-amphipatic proteins or peptides have to be modified by attachment of a lipid tail (e.g., palmitic acid). Immunization with ISCOMs induced both Th1-type humoral and cellular responses, including cytotoxic T lymphocytes that are important to fight against intracellular pathogens (190). Several studies have reported potent induction of mucosal immune responses, including robust IgA production in nasal washes and the lung, after nasal/pulmonary vaccination with ISCOMs harboring antigenic entities from Influenza virus (191194), respiratory syncitial virus (195), Hepatitis B virus (196) and measles (197). Protective efficacy was observed as well after vaccination with an Influenza subunit vaccine composed of ISCOMs (198), adjuvanted ISCOM-based anti-M. tuberculosis and anti-Influenza vaccines (199, 200) and Helicobacter pylori-Ags delivered via ISCOMs (201). In some cases, such immunization proved more efficient than parenteral injection (196, 202). Production of ISCOMs with an alternative saponin, derived from Quilaja brasiliensis, also allowed to induce mucosal local and distant IgA production after nasal delivery of an OVA-based vaccine (203). In addition, incorporation of DNA plasmid within the ISCOM matrix elicited potent anti-Haemophilus influenzae cellular and Ab responses in the nasopharynx of nasally immunized animals (204). Oral administration of ISCOM-based vaccines has been evaluated (205, 206); however, it seems that the generation of intestinal IgA responses was limited (207). Although ISCOMs are self-adjuvanted delivery systems, incorporation of the adjuvant CTA1-DD within the structure allowed to induce robust mucosal IgA production and T cell proliferation, together with systemic responses, after nasal administration (208). Such an approach has also been evaluated via oral delivery. Potent systemic Th1-type immune responses were induced, but unfortunately the mucosal compartments were not analyzed (209). CTA1-DD/ISCOMs incorporating major outer membrane protein from Chlamydia muridarum have also been administered via the vaginal route. Vaccination induced limited Ab responses, but clearly detectable CD4 T cell responses in vaginal tissues. This led to protection against a bacterial challenge, as demonstrated by reduction in bacterial shedding from the genital tract (49). Overall, the use of ISCOMs as a delivery vehicle for mucosal vaccination finds its best applicable for nasal administration, even though the sublingual route remains to be explored. Nevertheless, the difficulties related to the use of hydrophilic Ags that have to be modified before incorporation within ISCOMs, together with the reported toxicity of saponin, somehow limits the wide use of such vaccination approach.

Others

Oil-in-water nanoemulsions disperse into nanosized droplets and exhibit long-term colloidal stability. They can encapsulate hydrophilic or hydrophobic payload, respectively, and have been tested for nasal vaccination. A nanoemulsion based on soybean oil and cetylpiridinium chloride (W805EC) has been shown to deliver its antigenic payload across ciliated nasal epithelial cells and to the regional LNs in the NALT through migrating activated DCs (210). Via TLR-2 and TLR-4, such vaccine formulation promoted the induction of robust Ab and Th1-/Th17-type cellular responses and when associated with inactivated Influenza vaccine, generated a protective immunity against Influenza challenge (211). Such an approach similarly proved efficient in animal models to fight against M. tuberculosis, Hepatitis B, and Bacillus anthracis infections, or to generate HIV-1-specific mucosal immune responses (212, 213). Improved stability of nanoemulsions for mucosal delivery can now be achieved by the double emulsion water-in-oil-in-water technology, which has been applied both nasally and orally and resulted in robust production of systemic IgG and mucosal IgA (214). Alternatively, coupling of lipopeptides with a polylysine core induces the formation of 5–15 nm particles that can promote the generation of systemic and mucosal IgG/IgA and T cell responses after nasal administration. In these conditions, protective responses have been obtained against S. pyogenes infection (215, 216).

Human Application of Lipid Particles for Mucosal Vaccination

Currently approved mucosal vaccines are composed of live-attenuated or killed whole-pathogen cells that offer relatively good efficacy, but cannot be administered to young infants, immunocompromised people and the elderly due to potential safety issues. The majority of mucosally administered vaccines in humans are delivered via the oral route and directed against enteric infections such as polio, cholera, typhoid fever, and rotavirus infection (14). Oral polio vaccine has been used for more than 50 years with great success and is a prototypical vaccine for polio eradication in many countries. Interestingly, it demonstrated improved efficacy as compared to an inactivated pathogen vaccine injected parenterally (217219). Vivotif®, as well as Dukoral®, Shanchol™, Orochol®/Vaxchora™, and mORC-Vax™, are live-attenuated or whole-killed vaccines against Salmonella-induced typhoid fever or Vibrio cholerae infections, respectively (220222). As expected based on preclinical studies in animal models, their protective efficacy has been correlated with effector immune responses present at mucosal surfaces (in most cases detection of SIgA in mucosal fluids) and induction of plasma cells expressing gut-homing molecules specific for the small intestine and the colon (223225). In addition, and similar to observations in animal models, the choice of the administration route impacts on the tropism of the induced mucosal immune responses (226). Only FluMist®, a live-attenuated Influenza virus vaccine, is licensed for nasal administration (227). It demonstrates high level of protection against matched and mismatched viral strains in children and adults and proved more efficient than parenteral vaccination (228). Virus-specific mucosal IgA and systemic IgG responses with a possible role for cell-mediated immunity has been documented in vaccinated individuals (229). So far, the only adjuvant used for vaccinal application to mucosae is the B subunit of CT, which has been included in Dukoral® to improve the immunogenicity of the killed whole-pathogen Vibrio cholerae vaccine.

Despite many encouraging results obtained in proof-of-concept and preclinical animal models, a limited number of subunit vaccines based on lipidic delivery systems has been evaluated and/or approved for human use, especially for mucosal administration (Table 2) (230). Interestingly, in the context of mucosal vaccination, at least three formulations have been evaluated in early phase clinical trials. Nasal administration of the oil-in-water nanoemulsion W805EC combined with the approved inactivated systemic Influenza vaccine Fluzone® has demonstrated induction of IgA responses in nasal washes in a clinical evaluation (231). In addition, virosome-based and ISCOM-based Influenza vaccines are currently under development for administration via the nasal route (232, 233). Systemic injection of virosomes has been licensed for human vaccination against hepatitis A (Epaxal®) and Influenza (Inflexal V®) (234). Additional vaccines based on such technology have been tested in Phase 1 clinical trial for malaria and Influenza via the systemic route (232, 235). The advantage of such approach is that virosomes are self-adjuvanted, which is not the case for all other lipid-based delivery systems. Two Influenza vaccine formulations composed of squalene-based nanoemulsions (MF59® and AS03) are also approved for intramuscular injection in humans, with a particular focus on use in young children and elderly (236, 237). At least three additional strategies have been evaluated in humans. The most promising one is the use of the AS01 adjuvant, composed of liposomes made of highly unsaturated neutral phospholipids including MPLA and saponin QS21 (238). Successful phase III vaccination trials of such delivery system have been performed with the RTS,S/Mosquirix™ vaccine formulation against malaria (239) and the herpes-zooster vaccine (HZ/su) (240). CAF01 is an alternative formulation that is currently tested for parenteral vaccination against tuberculosis. Such liposomal bilayer preparation contains the cationic lipid DDA and the glycolipid TDB as immunostimulator (152). ISCOMs incorporating Ags E6 and E7 from HPV16 have been tested in women with cervical intraepithelial neoplasia and HIV-positive individuals with oncogenic HPV infections (241, 242). They demonstrated a safety profile and induced specific humoral and effector T cell responses. Similar results were obtained following vaccination with HCV-derived antigenic entities (243). Additional vaccine preparations based on lipidic constructs are currently evaluated to fight against pathogen infections, such as malaria, dengue fever, HIV, or Influenza (90, 230).

TABLE 2
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Table 2. Examples of licensed and in development lipid-based vaccines for human use.

Nevertheless, the above-mentioned studies are mainly performed with systemically injected formulations and only rare mucosal applications have been assessed. The use of mucosal route of administration requires that anatomical, functional, and immunological characteristics are taken into consideration and differences between humans and animals may results in poor inter-species translation of promising results (13). An organized NALT similar to that present in mice is not found in humans. By contrast, alternative inductive sites in the form of immune nodules are present in humans in the upper nasal cavity, in the concha, and in Waldeyer’s rings (adenoids, tonsils) (244). Pulmonary delivery of vaccines does not seem to be optimal as well, because BALT have only been reported in fetuses and young children, but not in healthy adults. In addition, the localization and phenotype of DCs in the nasal cavity and in the lung all differ between mice and humans. Taking into account these considerations, sublingual administration sounds like a promising strategy (42). Indeed, immunological and physiological organization of the oral cavity is similar in both mice and humans, with documented presence of the same DC subsets, such as Langerhans cells, capable of eliciting immunogenic or tolerogenic responses depending on the applied formulations. Vaccination via the sublingual route has been mostly evaluated in humans for allergen immunotherapy, and has been shown to induce systemic IgG (focus of allergy) (245). Therefore, evaluation of the mucosal vaccination approach to protect against infectious diseases is highly relevant and needs evaluation. In addition, although the gut immune system is relatively similar between both species, oral administration of subunit vaccines is further complicated due to the constraints related to the stability of formulations in the aggressive environment of the digestive tract. On the top of anatomical considerations, the age-related decline in the immune function, possibly related to the documented decrease in M cell differentiation with age, represents a drawback for immunization in eldery people.

Conclusion and Perspectives

Although vaccination has led to the control of several diseases and has demonstrated substantial technological progresses, humans still suffer from infections leading to death and increasing health costs. Many infectious diseases for which the development of effective vaccines is urgently needed include those transmitted through various mucosal routes that affect the gastrointestinal tract (E. coli, Salmonella, Shigella, Vibrio cholerae, H. pylori), the respiratory tract (Influenza, M. tuberculosis, respiratory syncitial virus) or are sexually transmitted (HIV, Chlamydia) (15). To date, parenteral vaccination represents an important part of the administered vaccines, despite the fact that they poorly induce mucosal immune responses. Furthermore, the requirement for sterile needles, their subsequent elimination, the associated cost, and the cold chain’s requirement in many instances prompt a shift toward reduced frequencies of intramuscular vaccination. In addition, most of the currently licensed vaccines can only be administered over 2 years of age for safety reasons; similar considerations apply for immunodeficient individuals and elderly (13). Therefore, the mucosal application of subunit vaccines represents a sound alternative to broaden the target population that could benefit from vaccination. Cues into this direction include recent advances in the understanding of mucosal immunity as well as assessment of correlates of protection may help to develop promising mucosal vaccines; in this respect, design of novel effective delivery strategies will permit to achieve mucosal vaccines that induce protective neutralizing SIgA, together with CTLs and effector CD4 T cells mainly secreting IFN-γ and IL-17. Moreover, because they are considered as safe, subunit vaccines can certainly be administered to neonates and young infants who already possess a functional mucosal immune system (13).

Lipid-based particles fulfill the requirements for better efficiency, safety, low-dose Ag, and ease to handle logistically. They can deliver a wide range of antigenic entities upon mucosal delivery and can be tailored to obtain vaccine formulations with appropriate properties to address questions related to the mechanisms invlolved in the control of the pathogen and the route of administration. Robust and sustained induction of immune responses, comprising production of SIgA at mucosal surfaces, together with helper and cytotoxic T cells, often correlate with protection in defined animal models under study; this will undoubtly help to drive vaccine development toward the right direction. It remains that a strict comparative analysis of the formulations and administration routes to be used against a particular infectious disease is rarely performed within the same study. To contribute to the identification of such a missing piece in this complex puzzle would be an asset in order to optimize mucosal vaccination. The same lack of information must be filled up when one deals with the definition of the optimal dosing and schedule of administration to ensure efficient priming and boosting of immune responses aiming at reaching optimal magnitude and maintenance.

Some lipid-based preparations have the advantage of being lyophilized, thus allowing to simplify the logistics usually necessary for cold chain. Indeed, some of these formulations can be stored at room temperature for several months and can be administered in such form via the nasal, oral, or sublingual routes. Dry powder nasal vaccines have already been tested (246), oral delivery of capsules is not a problem (222), and many allergy-related immunotherapy tablets have been considered for sublingual administration (247). Moreover, lipid-based preparations can be aerosolized, which might represent an alternative procedure to keeping stable vaccine preparations. Overall, great expectations are coming from the lipid-based vaccine formulations currently evaluated in clinical trials in humans, which together with the different mechanisms of mucosal immunity recently unraveled, may likely favor the development of future mucosal vaccines suitable for a majority of individuals, thanks to the combinatorial flexibility offered by the nature of the constituents available.

Author Contributions

BC and GB planned the manuscript and wrote sections of the manuscript. Both authors read and approved the submitted version of the manuscript.

Conflict of Interest Statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Funding

This work was supported by the Swiss Science Research Foundation (grant 3100-156806 and grant 310030_175686 to BC).

References

1. Andre FE. Vaccinology: past achievements, present roadblocks and future promises. Vaccine (2003) 21(7–8):593–5. doi:10.1016/S0264-410X(02)00702-8

PubMed Abstract | CrossRef Full Text | Google Scholar

2. Plotkin SA. Vaccines: past, present and future. Nat Med (2005) 11(4 Suppl):S5–11. doi:10.1038/nm1209

PubMed Abstract | CrossRef Full Text | Google Scholar

3. Pulendran B, Ahmed R. Immunological mechanisms of vaccination. Nat Immunol (2011) 12(6):509–17. doi:10.1038/ni.2039

PubMed Abstract | CrossRef Full Text | Google Scholar

4. Rueckert C, Guzman CA. Vaccines: from empirical development to rational design. PLoS Pathog (2012) 8(11):e1003001. doi:10.1371/journal.ppat.1003001

PubMed Abstract | CrossRef Full Text | Google Scholar

5. De Temmerman ML, Rejman J, Demeester J, Irvine DJ, Gander B, De Smedt SC. Particulate vaccines: on the quest for optimal delivery and immune response. Drug Discov Today (2011) 16(13–14):569–82. doi:10.1016/j.drudis.2011.04.006

PubMed Abstract | CrossRef Full Text | Google Scholar

6. Woodrow KA, Bennett KM, Lo DD. Mucosal vaccine design and delivery. Annu Rev Biomed Eng (2012) 14:17–46. doi:10.1146/annurev-bioeng-071811-150054

CrossRef Full Text | Google Scholar

7. Lamichhane A, Azegamia T, Kiyonoa H. The mucosal immune system for vaccine development. Vaccine (2014) 32(49):6711–23. doi:10.1016/j.vaccine.2014.08.089

PubMed Abstract | CrossRef Full Text | Google Scholar

8. Iwata M, Hirakiyama A, Eshima Y, Kagechika H, Kato C, Song SY. Retinoic acid imprints gut-homing specificity on T cells. Immunity (2004) 21(4):527–38. doi:10.1016/j.immuni.2004.08.011

PubMed Abstract | CrossRef Full Text | Google Scholar

9. Mora JR, Iwata M, Eksteen B, Song SY, Junt T, Senman B, et al. Generation of gut-homing IgA-secreting B cells by intestinal dendritic cells. Science (2006) 314(5802):1157–60. doi:10.1126/science.1132742

PubMed Abstract | CrossRef Full Text | Google Scholar

10. Mora JR, Bono MR, Manjunath N, Weninger W, Cavanagh LL, Rosemblatt M, et al. Selective imprinting of gut-homing T cells by Peyer’s patch dendritic cells. Nature (2003) 424(6944):88–93. doi:10.1038/nature01726

PubMed Abstract | CrossRef Full Text | Google Scholar

11. Neutra MR, Kozlowski PA. Mucosal vaccines: the promise and the challenge. Nat Rev Immunol (2006) 6(2):148–58. doi:10.1038/nri1777

PubMed Abstract | CrossRef Full Text | Google Scholar

12. Mestecky J, Russell MW, Elson CO. Perspectives on mucosal vaccines: is mucosal tolerance a barrier? J Immunol (2007) 179(9):5633–8. doi:10.4049/jimmunol.179.9.5633

PubMed Abstract | CrossRef Full Text | Google Scholar

13. Shakya AK, Chowdhury MYE, Tao W, Gill HS. Mucosal vaccine delivery: current state and a pediatric perspective. J Control Release (2016) 240:394–413. doi:10.1016/j.jconrel.2016.02.014

PubMed Abstract | CrossRef Full Text | Google Scholar

14. Lycke N. Recent progress in mucosal vaccine development: potential and limitations. Nat Rev Immunol (2012) 12(8):592–605. doi:10.1038/nri3251

PubMed Abstract | CrossRef Full Text | Google Scholar

15. Czerkinsky C, Holmgren J. Topical immunization strategies. Mucosal Immunol (2010) 3(6):545–55. doi:10.1038/mi.2010.55

PubMed Abstract | CrossRef Full Text | Google Scholar

16. Heritage PL, Underdown BJ, Arsenault AL, Snider DP, McDermott MR. Comparison of murine nasal-associated lymphoid tissue and Peyer’s patches. Am J Respir Crit Care Med (1997) 156(4 Pt 1):1256–62. doi:10.1164/ajrccm.156.4.97-03017

PubMed Abstract | CrossRef Full Text | Google Scholar

17. Brandtzaeg P. Mucosal immunity: induction, dissemination, and effector functions. Scand J Immunol (2009) 70(6):505–15. doi:10.1111/j.1365-3083.2009.02319.x

PubMed Abstract | CrossRef Full Text | Google Scholar

18. Corthesy B. Multi-faceted functions of secretory IgA at mucosal surfaces. Front Immunol (2013) 4:185. doi:10.3389/fimmu.2013.00185

PubMed Abstract | CrossRef Full Text | Google Scholar

19. Lelouard H, Fallet M, de Bovis B, Meresse S, Gorvel JP. Peyer’s patch dendritic cells sample antigens by extending dendrites through M cell-specific transcellular pores. Gastroenterology (2012) 142(3):592–601.e3. doi:10.1053/j.gastro.2011.11.039

PubMed Abstract | CrossRef Full Text | Google Scholar

20. Niess JH, Brand S, Gu X, Landsman L, Jung S, McCormick BA, et al. CX3CR1-mediated dendritic cell access to the intestinal lumen and bacterial clearance. Science (2005) 307(5707):254–8. doi:10.1126/science.1102901

PubMed Abstract | CrossRef Full Text | Google Scholar

21. Chieppa M, Rescigno M, Huang AY, Germain RN. Dynamic imaging of dendritic cell extension into the small bowel lumen in response to epithelial cell TLR engagement. J Exp Med (2006) 203(13):2841–52. doi:10.1084/jem.20061884

PubMed Abstract | CrossRef Full Text | Google Scholar

22. Brandtzaeg P. The gut as communicator between environment and host: immunological consequences. Eur J Pharmacol (2011) 668(Suppl 1):S16–32. doi:10.1016/j.ejphar.2011.07.006

PubMed Abstract | CrossRef Full Text | Google Scholar

23. Jia Y, Krishnan L, Omri A. Nasal and pulmonary vaccine delivery using particulate carriers. Expert Opin Drug Deliv (2015) 12(6):993–1008. doi:10.1517/17425247.2015.1044435

PubMed Abstract | CrossRef Full Text | Google Scholar

24. Corr SC, Gahan CC, Hill C. M-cells: origin, morphology and role in mucosal immunity and microbial pathogenesis. FEMS Immunol Med Microbiol (2008) 52(1):2–12. doi:10.1111/j.1574-695X.2007.00359.x

PubMed Abstract | CrossRef Full Text | Google Scholar

25. Iwasaki A. Antiviral immune responses in the genital tract: clues for vaccines. Nat Rev Immunol (2010) 10(10):699–711. doi:10.1038/nri2836

PubMed Abstract | CrossRef Full Text | Google Scholar

26. Song JH, Kim JI, Kwon HJ, Shim DH, Parajuli N, Cuburu N, et al. CCR7-CCL19/CCL21-regulated dendritic cells are responsible for effectiveness of sublingual vaccination. J Immunol (2009) 182(11):6851–60. doi:10.4049/jimmunol.0803568

PubMed Abstract | CrossRef Full Text | Google Scholar

27. Czerkinsky C, Holmgren J. Mucosal delivery routes for optimal immunization: targeting immunity to the right tissues. Curr Top Microbiol Immunol (2012) 354:1–18. doi:10.1007/82_2010_112

PubMed Abstract | CrossRef Full Text | Google Scholar

28. Laffont S, Siddiqui KR, Powrie F. Intestinal inflammation abrogates the tolerogenic properties of MLN CD103+ dendritic cells. Eur J Immunol (2010) 40(7):1877–83. doi:10.1002/eji.200939957

PubMed Abstract | CrossRef Full Text | Google Scholar

29. Corthesy B. Roundtrip ticket for secretory IgA: role in mucosal homeostasis? J Immunol (2007) 178(1):27–32. doi:10.4049/jimmunol.178.1.27

PubMed Abstract | CrossRef Full Text | Google Scholar

30. Mowat AM. Anatomical basis of tolerance and immunity to intestinal antigens. Nat Rev Immunol (2003) 3(4):331–41. doi:10.1038/nri1057

PubMed Abstract | CrossRef Full Text | Google Scholar

31. Fagarasan S, Kawamoto S, Kanagawa O, Suzuki K. Adaptive immune regulation in the gut: T cell-dependent and T cell-independent IgA synthesis. Annu Rev Immunol (2010) 28:243–73. doi:10.1146/annurev-immunol-030409-101314

PubMed Abstract | CrossRef Full Text | Google Scholar

32. Belyakov IM, Hammond SA, Ahlers JD, Glenn GM, Berzofsky JA. Transcutaneous immunization induces mucosal CTLs and protective immunity by migration of primed skin dendritic cells. J Clin Invest (2004) 113(7):998–1007. doi:10.1172/JCI20261

PubMed Abstract | CrossRef Full Text | Google Scholar

33. Gavillet BM, Mondoulet L, Dhelft V, Eberhardt CS, Auderset F, Pham HT, et al. Needle-free and adjuvant-free epicutaneous boosting of pertussis immunity: preclinical proof of concept. Vaccine (2015) 33(30):3450–5. doi:10.1016/j.vaccine.2015.05.089

PubMed Abstract | CrossRef Full Text | Google Scholar

34. Hirobe S, Okada N, Nakagawa S. Transcutaneous vaccines – current and emerging strategies. Expert Opin Drug Deliv (2013) 10(4):485–98. doi:10.1517/17425247.2013.760542

CrossRef Full Text | Google Scholar

35. Bernocchi B, Carpentier R, Betbeder D. Nasal nanovaccines. Int J Pharm (2017) 530(1–2):128–38. doi:10.1016/j.ijpharm.2017.07.012

PubMed Abstract | CrossRef Full Text | Google Scholar

36. Vujanic A, Snibson KJ, Wee JL, Edwards SJ, Pearse MJ, Scheerlinck JP, et al. Long-term antibody and immune memory response induced by pulmonary delivery of the influenza Iscomatrix vaccine. Clin Vaccine Immunol (2012) 19(1):79–83. doi:10.1128/CVI.05265-11

PubMed Abstract | CrossRef Full Text | Google Scholar

37. Hodge LM, Simecka JW. Role of upper and lower respiratory tract immunity in resistance to mycoplasma respiratory disease. J Infect Dis (2002) 186(2):290–4. doi:10.1086/341280

PubMed Abstract | CrossRef Full Text | Google Scholar

38. Woolard MD, Hodge LM, Jones HP, Schoeb TR, Simecka JW. The upper and lower respiratory tracts differ in their requirement of IFN-gamma and IL-4 in controlling respiratory mycoplasma infection and disease. J Immunol (2004) 172(11):6875–83. doi:10.4049/jimmunol.172.11.6875

PubMed Abstract | CrossRef Full Text | Google Scholar

39. Soares E, Borges O. Oral vaccination through Peyer’s patches: update on particle uptake. Curr Drug Deliv (2017). doi:10.2174/1567201814666170825153955

PubMed Abstract | CrossRef Full Text | Google Scholar

40. Cuburu N, Kweon MN, Song JH, Hervouet C, Luci C, Sun JB, et al. Sublingual immunization induces broad-based systemic and mucosal immune responses in mice. Vaccine (2007) 25(51):8598–610. doi:10.1016/j.vaccine.2007.09.073

PubMed Abstract | CrossRef Full Text | Google Scholar

41. Shim BS, Stadler K, Nguyen HH, Yun CH, Kim DW, Chang J, et al. Sublingual immunization with recombinant adenovirus encoding SARS-CoV spike protein induces systemic and mucosal immunity without redirection of the virus to the brain. Virol J (2012) 9:215. doi:10.1186/1743-422X-9-215

PubMed Abstract | CrossRef Full Text | Google Scholar

42. Kraan H, Vrieling H, Czerkinsky C, Jiskoot W, Kersten G, Amorij JP. Buccal and sublingual vaccine delivery. J Control Release (2014) 190:580–92. doi:10.1016/j.jconrel.2014.05.060

PubMed Abstract | CrossRef Full Text | Google Scholar

43. Song JH, Nguyen HH, Cuburu N, Horimoto T, Ko SY, Park SH, et al. Sublingual vaccination with influenza virus protects mice against lethal viral infection. Proc Natl Acad Sci U S A (2008) 105(5):1644–9. doi:10.1073/pnas.0708684105

PubMed Abstract | CrossRef Full Text | Google Scholar

44. Ma Y, Tao W, Krebs SJ, Sutton WF, Haigwood NL, Gill HS. Vaccine delivery to the oral cavity using coated microneedles induces systemic and mucosal immunity. Pharm Res (2014) 31(9):2393–403. doi:10.1007/s11095-014-1335-1

PubMed Abstract | CrossRef Full Text | Google Scholar

45. Zhen Y, Wang N, Gao Z, Ma X, Wei B, Deng Y, et al. Multifunctional liposomes constituting microneedles induced robust systemic and mucosal immunoresponses against the loaded antigens via oral mucosal vaccination. Vaccine (2015) 33(35):4330–40. doi:10.1016/j.vaccine.2015.03.081

PubMed Abstract | CrossRef Full Text | Google Scholar

46. Zhao X, Deak E, Soderberg K, Linehan M, Spezzano D, Zhu J, et al. Vaginal submucosal dendritic cells, but not Langerhans cells, induce protective Th1 responses to herpes simplex virus-2. J Exp Med (2003) 197(2):153–62. doi:10.1084/jem.20021109

CrossRef Full Text | Google Scholar

47. Prabhala RH, Wira CR. Influence of estrous cycle and estradiol on mitogenic responses of splenic T- and B-lymphocytes. Adv Exp Med Biol (1995) 371A:379–81. doi:10.1007/978-1-4615-1941-6_78

PubMed Abstract | CrossRef Full Text | Google Scholar

48. Seavey MM, Mosmann TR. Estradiol-induced vaginal mucus inhibits antigen penetration and CD8(+) T cell priming in response to intravaginal immunization. Vaccine (2009) 27(17):2342–9. doi:10.1016/j.vaccine.2009.02.025

PubMed Abstract | CrossRef Full Text | Google Scholar

49. Marks E, Helgeby A, Andersson JO, Schon K, Lycke NY. CD4(+) T-cell immunity in the female genital tract is critically dependent on local mucosal immunization. Eur J Immunol (2011) 41(9):2642–53. doi:10.1002/eji.201041297

CrossRef Full Text | Google Scholar

50. Kastenmuller W, Kastenmuller K, Kurts C, Seder RA. Dendritic cell-targeted vaccines – hope or hype? Nat Rev Immunol (2014) 14(10):705–11. doi:10.1038/nri3727

CrossRef Full Text | Google Scholar

51. Iwasaki A. Mucosal dendritic cells. Annu Rev Immunol (2007) 25:381–418. doi:10.1146/annurev.immunol.25.022106.141634

PubMed Abstract | CrossRef Full Text | Google Scholar

52. Israel EJ, Taylor S, Wu Z, Mizoguchi E, Blumberg RS, Bhan A, et al. Expression of the neonatal Fc receptor, FcRn, on human intestinal epithelial cells. Immunology (1997) 92(1):69–74. doi:10.1046/j.1365-2567.1997.00326.x

PubMed Abstract | CrossRef Full Text | Google Scholar

53. Spiekermann GM, Finn PW, Ward ES, Dumont J, Dickinson BL, Blumberg RS, et al. Receptor-mediated immunoglobulin G transport across mucosal barriers in adult life: functional expression of FcRn in the mammalian lung. J Exp Med (2002) 196(3):303–10. doi:10.1084/jem.20020400

PubMed Abstract | CrossRef Full Text | Google Scholar

54. Zhu X, Meng G, Dickinson BL, Li X, Mizoguchi E, Miao L, et al. MHC class I-related neonatal Fc receptor for IgG is functionally expressed in monocytes, intestinal macrophages, and dendritic cells. J Immunol (2001) 166(5):3266–76. doi:10.4049/jimmunol.166.5.3266

PubMed Abstract | CrossRef Full Text | Google Scholar

55. Tiwari B, Agarwal A, Kharya AK, Lariya N, Saraogi G, Agrawal H, et al. Immunoglobulin immobilized liposomal constructs for transmucosal vaccination through nasal route. J Liposome Res (2011) 21(3):181–93. doi:10.3109/08982104.2010.498003

PubMed Abstract | CrossRef Full Text | Google Scholar

56. Pridgen EM, Alexis F, Kuo TT, Levy-Nissenbaum E, Karnik R, Blumberg RS, et al. Transepithelial transport of Fc-targeted nanoparticles by the neonatal fc receptor for oral delivery. Sci Transl Med (2013) 5(213):213ra167. doi:10.1126/scitranslmed.3007049

PubMed Abstract | CrossRef Full Text | Google Scholar

57. Yoshida M, Claypool SM, Wagner JS, Mizoguchi E, Mizoguchi A, Roopenian DC, et al. Human neonatal Fc receptor mediates transport of IgG into luminal secretions for delivery of antigens to mucosal dendritic cells. Immunity (2004) 20(6):769–83. doi:10.1016/j.immuni.2004.05.007

PubMed Abstract | CrossRef Full Text | Google Scholar

58. Alfsen A, Bomsel M. HIV-1 gp41 envelope residues 650-685 exposed on native virus act as a lectin to bind epithelial cell galactosyl ceramide. J Biol Chem (2002) 277(28):25649–59. doi:10.1074/jbc.M200554200

PubMed Abstract | CrossRef Full Text | Google Scholar

59. Kim SH, Lee KY, Kim J, Park SM, Park BK, Jang YS. Identification of a peptide enhancing mucosal and systemic immune responses against EGFP after oral administration in mice. Mol Cells (2006) 21(2):244–50.

PubMed Abstract | Google Scholar

60. Rajapaksa TE, Bennett KM, Hamer M, Lytle C, Rodgers VG, Lo DD. Intranasal M cell uptake of nanoparticles is independently influenced by targeting ligands and buffer ionic strength. J Biol Chem (2010) 285(31):23739–46. doi:10.1074/jbc.M110.126359

PubMed Abstract | CrossRef Full Text | Google Scholar

61. Shima H, Watanabe T, Fukuda S, Fukuoka S, Ohara O, Ohno H. A novel mucosal vaccine targeting Peyer’s patch M cells induces protective antigen-specific IgA responses. Int Immunol (2014) 26(11):619–25. doi:10.1093/intimm/dxu061

PubMed Abstract | CrossRef Full Text | Google Scholar

62. Ma T, Wang L, Yang T, Ma G, Wang S. M-cell targeted polymeric lipid nanoparticles containing a toll-like receptor agonist to boost oral immunity. Int J Pharm (2014) 473(1–2):296–303. doi:10.1016/j.ijpharm.2014.06.052

PubMed Abstract | CrossRef Full Text | Google Scholar

63. Kim SH, Seo KW, Kim J, Lee KY, Jang YS. The M cell-targeting ligand promotes antigen delivery and induces antigen-specific immune responses in mucosal vaccination. J Immunol (2010) 185(10):5787–95. doi:10.4049/jimmunol.0903184

PubMed Abstract | CrossRef Full Text | Google Scholar

64. Kim SH, Jung DI, Yang IY, Jang SH, Kim J, Truong TT, et al. Application of an M-cell-targeting ligand for oral vaccination induces efficient systemic and mucosal immune responses against a viral antigen. Int Immunol (2013) 25(11):623–32. doi:10.1093/intimm/dxt029

PubMed Abstract | CrossRef Full Text | Google Scholar

65. Jiang T, Singh B, Li HS, Kim YK, Kang SK, Nah JW, et al. Targeted oral delivery of BmpB vaccine using porous PLGA microparticles coated with M cell homing peptide-coupled chitosan. Biomaterials (2014) 35(7):2365–73. doi:10.1016/j.biomaterials.2013.11.073

PubMed Abstract | CrossRef Full Text | Google Scholar

66. Foster N, Clark MA, Jepson MA, Hirst BH. Ulex europaeus 1 lectin targets microspheres to mouse Peyer’s patch M-cells in vivo. Vaccine (1998) 16(5):536–41. doi:10.1016/S0264-410X(97)00222-3

PubMed Abstract | CrossRef Full Text | Google Scholar

67. Manocha M, Pal PC, Chitralekha KT, Thomas BE, Tripathi V, Gupta SD, et al. Enhanced mucosal and systemic immune response with intranasal immunization of mice with HIV peptides entrapped in PLG microparticles in combination with Ulex Europaeus-I lectin as M cell target. Vaccine (2005) 23(48–49):5599–617. doi:10.1016/j.vaccine.2005.06.031

PubMed Abstract | CrossRef Full Text | Google Scholar

68. Nochi T, Yuki Y, Matsumura A, Mejima M, Terahara K, Kim DY, et al. A novel M cell-specific carbohydrate-targeted mucosal vaccine effectively induces antigen-specific immune responses. J Exp Med (2007) 204(12):2789–96. doi:10.1084/jem.20070607

PubMed Abstract | CrossRef Full Text | Google Scholar

69. Clark MA, Jepson MA, Simmons NL, Booth TA, Hirst BH. Differential expression of lectin-binding sites defines mouse intestinal M-cells. J Histochem Cytochem (1993) 41(11):1679–87. doi:10.1177/41.11.7691933

PubMed Abstract | CrossRef Full Text | Google Scholar

70. Giannasca PJ, Giannasca KT, Leichtner AM, Neutra MR. Human intestinal M cells display the sialyl Lewis A antigen. Infect Immun (1999) 67(2):946–53.

PubMed Abstract | Google Scholar

71. Rochereau N, Drocourt D, Perouzel E, Pavot V, Redelinghuys P, Brown GD, et al. Dectin-1 is essential for reverse transcytosis of glycosylated SIgA-antigen complexes by intestinal M cells. PLoS Biol (2013) 11(9):e1001658. doi:10.1371/journal.pbio.1001658

PubMed Abstract | CrossRef Full Text | Google Scholar

72. Rol N, Favre L, Benyacoub J, Corthesy B. The role of secretory immunoglobulin A in the natural sensing of commensal bacteria by mouse Peyer’s patch dendritic cells. J Biol Chem (2012) 287(47):40074–82. doi:10.1074/jbc.M112.405001

PubMed Abstract | CrossRef Full Text | Google Scholar

73. Bachmann MF, Jennings GT. Vaccine delivery: a matter of size, geometry, kinetics and molecular patterns. Nat Rev Immunol (2010) 10(11):787–96. doi:10.1038/nri2868

PubMed Abstract | CrossRef Full Text | Google Scholar

74. Sun H, Pollock KG, Brewer JM. Analysis of the role of vaccine adjuvants in modulating dendritic cell activation and antigen presentation in vitro. Vaccine (2003) 21(9–10):849–55. doi:10.1016/S0264-410X(02)00531-5

PubMed Abstract | CrossRef Full Text | Google Scholar

75. Sahay G, Alakhova DY, Kabanov AV. Endocytosis of nanomedicines. J Control Release (2010) 145(3):182–95. doi:10.1016/j.jconrel.2010.01.036

PubMed Abstract | CrossRef Full Text | Google Scholar

76. Xiang SD, Scholzen A, Minigo G, David C, Apostolopoulos V, Mottram PL, et al. Pathogen recognition and development of particulate vaccines: does size matter? Methods (2006) 40(1):1–9. doi:10.1016/j.ymeth.2006.05.016

PubMed Abstract | CrossRef Full Text | Google Scholar

77. Mann JF, Shakir E, Carter KC, Mullen AB, Alexander J, Ferro VA. Lipid vesicle size of an oral influenza vaccine delivery vehicle influences the Th1/Th2 bias in the immune response and protection against infection. Vaccine (2009) 27(27):3643–9. doi:10.1016/j.vaccine.2009.03.040

PubMed Abstract | CrossRef Full Text | Google Scholar

78. Brewer JM, Tetley L, Richmond J, Liew FY, Alexander J. Lipid vesicle size determines the Th1 or Th2 response to entrapped antigen. J Immunol (1998) 161(8):4000–7.

PubMed Abstract | Google Scholar

79. Henriksen-Lacey M, Devitt A, Perrie Y. The vesicle size of DDA:TDB liposomal adjuvants plays a role in the cell-mediated immune response but has no significant effect on antibody production. J Control Release (2011) 154(2):131–7. doi:10.1016/j.jconrel.2011.05.019

PubMed Abstract | CrossRef Full Text | Google Scholar

80. Vila A, Sanchez A, Evora C, Soriano I, McCallion O, Alonso MJ. PLA-PEG particles as nasal protein carriers: the influence of the particle size. Int J Pharm (2005) 292(1–2):43–52. doi:10.1016/j.ijpharm.2004.09.002

PubMed Abstract | CrossRef Full Text | Google Scholar

81. Thomas C, Gupta V, Ahsan F. Particle size influences the immune response produced by hepatitis B vaccine formulated in inhalable particles. Pharm Res (2010) 27(5):905–19. doi:10.1007/s11095-010-0094-x

PubMed Abstract | CrossRef Full Text | Google Scholar

82. Lai SK, Wang YY, Hida K, Cone R, Hanes J. Nanoparticles reveal that human cervicovaginal mucus is riddled with pores larger than viruses. Proc Natl Acad Sci U S A (2010) 107(2):598–603. doi:10.1073/pnas.0911748107

PubMed Abstract | CrossRef Full Text | Google Scholar

83. Bajka BH, Rigby NM, Cross KL, Macierzanka A, Mackie AR. The influence of small intestinal mucus structure on particle transport ex vivo. Colloids Surf B Biointerfaces (2015) 135:73–80. doi:10.1016/j.colsurfb.2015.07.038

PubMed Abstract | CrossRef Full Text | Google Scholar

84. Kim TW, Chung H, Kwon IC, Sung HC, Jeong SY. In vivo gene transfer to the mouse nasal cavity mucosa using a stable cationic lipid emulsion. Mol Cells (2000) 10(2):142–7. doi:10.1007/s10059-000-0142-1

PubMed Abstract | CrossRef Full Text | Google Scholar

85. Ingvarsson PT, Rasmussen IS, Viaene M, Irlik PJ, Nielsen HM, Foged C. The surface charge of liposomal adjuvants is decisive for their interactions with the Calu-3 and A549 airway epithelial cell culture models. Eur J Pharm Biopharm (2014) 87(3):480–8. doi:10.1016/j.ejpb.2014.04.001

PubMed Abstract | CrossRef Full Text | Google Scholar

86. Korsholm KS, Agger EM, Foged C, Christensen D, Dietrich J, Andersen CS, et al. The adjuvant mechanism of cationic dimethyldioctadecylammonium liposomes. Immunology (2007) 121(2):216–26. doi:10.1111/j.1365-2567.2007.02560.x

PubMed Abstract | CrossRef Full Text | Google Scholar

87. Foged C, Arigita C, Sundblad A, Jiskoot W, Storm G, Frokjaer S. Interaction of dendritic cells with antigen-containing liposomes: effect of bilayer composition. Vaccine (2004) 22(15–16):1903–13. doi:10.1016/j.vaccine.2003.11.008

PubMed Abstract | CrossRef Full Text | Google Scholar

88. Watson DS, Endsley AN, Huang L. Design considerations for liposomal vaccines: influence of formulation parameters on antibody and cell-mediated immune responses to liposome associated antigens. Vaccine (2012) 30(13):2256–72. doi:10.1016/j.vaccine.2012.01.070

PubMed Abstract | CrossRef Full Text | Google Scholar

89. Heurtault B, Frisch B, Pons F. Liposomes as delivery systems for nasal vaccination: strategies and outcomes. Expert Opin Drug Deliv (2010) 7(7):829–44. doi:10.1517/17425247.2010.488687

PubMed Abstract | CrossRef Full Text | Google Scholar

90. Bernasconi V, Norling K, Bally M, Hook F, Lycke NY. Mucosal vaccine development based on liposome technology. J Immunol Res (2016) 2016:5482087. doi:10.1155/2016/5482087

PubMed Abstract | CrossRef Full Text | Google Scholar

91. Therien HM, Shahum E. Importance of physical association between antigen and liposomes in liposomes adjuvanticity. Immunol Lett (1989) 22(4):253–8. doi:10.1016/0165-2478(89)90161-2

PubMed Abstract | CrossRef Full Text | Google Scholar

92. Barnier-Quer C, Elsharkawy A, Romeijn S, Kros A, Jiskoot W. Adjuvant effect of cationic liposomes for subunit influenza vaccine: influence of antigen loading method, cholesterol and immune modulators. Pharmaceutics (2013) 5(3):392–410. doi:10.3390/pharmaceutics5030392

PubMed Abstract | CrossRef Full Text | Google Scholar

93. Minato S, Iwanaga K, Kakemi M, Yamashita S, Oku N. Application of polyethyleneglycol (PEG)-modified liposomes for oral vaccine: effect of lipid dose on systemic and mucosal immunity. J Control Release (2003) 89(2):189–97. doi:10.1016/S0168-3659(03)00093-2

PubMed Abstract | CrossRef Full Text | Google Scholar

94. Brewer MG, DiPiazza A, Acklin J, Feng C, Sant AJ, Dewhurst S. Nanoparticles decorated with viral antigens are more immunogenic at low surface density. Vaccine (2017) 35(5):774–81. doi:10.1016/j.vaccine.2016.12.049

PubMed Abstract | CrossRef Full Text | Google Scholar

95. Saade F, Petrovsky N. Technologies for enhanced efficacy of DNA vaccines. Expert Rev Vaccines (2012) 11(2):189–209. doi:10.1586/erv.11.188

PubMed Abstract | CrossRef Full Text | Google Scholar

96. Gregoriadis G, Bacon A, Caparros-Wanderley W, McCormack B. A role for liposomes in genetic vaccination. Vaccine (2002) 20(Suppl 5):B1–9. doi:10.1016/S0264-410X(02)00514-5

PubMed Abstract | CrossRef Full Text | Google Scholar

97. Henderson A, Propst K, Kedl R, Dow S. Mucosal immunization with liposome-nucleic acid adjuvants generates effective humoral and cellular immunity. Vaccine (2011) 29(32):5304–12. doi:10.1016/j.vaccine.2011.05.009

PubMed Abstract | CrossRef Full Text | Google Scholar

98. Wang D, Xu J, Feng Y, Liu Y, McHenga SS, Shan F, et al. Liposomal oral DNA vaccine (Mycobacterium DNA) elicits immune response. Vaccine (2010) 28(18):3134–42. doi:10.1016/j.vaccine.2010.02.058

PubMed Abstract | CrossRef Full Text | Google Scholar

99. Midoux P, Pichon C. Lipid-based mRNA vaccine delivery systems. Expert Rev Vaccines (2015) 14(2):221–34. doi:10.1586/14760584.2015.986104

PubMed Abstract | CrossRef Full Text | Google Scholar

100. Phua KK, Staats HF, Leong KW, Nair SK. Intranasal mRNA nanoparticle vaccination induces prophylactic and therapeutic anti-tumor immunity. Sci Rep (2014) 4:5128. doi:10.1038/srep05128

PubMed Abstract | CrossRef Full Text | Google Scholar

101. Palchetti S, Digiacomo L, Pozzi D, Peruzzi G, Micarelli E, Mahmoudi M, et al. Nanoparticles-cell association predicted by protein corona fingerprints. Nanoscale (2016) 8(25):12755–63. doi:10.1039/c6nr03898k

PubMed Abstract | CrossRef Full Text | Google Scholar

102. Iwanaga K, Ono S, Narioka K, Kakemi M, Morimoto K, Yamashita S, et al. Application of surface-coated liposomes for oral delivery of peptide: effects of coating the liposome’s surface on the GI transit of insulin. J Pharm Sci (1999) 88(2):248–52. doi:10.1021/js980235x

PubMed Abstract | CrossRef Full Text | Google Scholar

103. Oberoi HS, Yorgensen YM, Morasse A, Evans JT, Burkhart DJ. PEG modified liposomes containing CRX-601 adjuvant in combination with methylglycol chitosan enhance the murine sublingual immune response to influenza vaccination. J Control Release (2016) 223:64–74. doi:10.1016/j.jconrel.2015.11.006

PubMed Abstract | CrossRef Full Text | Google Scholar

104. Lai SK, O’Hanlon DE, Harrold S, Man ST, Wang YY, Cone R, et al. Rapid transport of large polymeric nanoparticles in fresh undiluted human mucus. Proc Natl Acad Sci U S A (2007) 104(5):1482–7. doi:10.1073/pnas.0608611104

PubMed Abstract | CrossRef Full Text | Google Scholar

105. Huang Y, Leobandung W, Foss A, Peppas NA. Molecular aspects of muco- and bioadhesion: tethered structures and site-specific surfaces. J Control Release (2000) 65(1–2):63–71. doi:10.1016/S0168-3659(99)00233-3

PubMed Abstract | CrossRef Full Text | Google Scholar

106. Lai SK, Wang YY, Hanes J. Mucus-penetrating nanoparticles for drug and gene delivery to mucosal tissues. Adv Drug Deliv Rev (2009) 61(2):158–71. doi:10.1016/j.addr.2008.11.002

PubMed Abstract | CrossRef Full Text | Google Scholar

107. Augst AD, Kong HJ, Mooney DJ. Alginate hydrogels as biomaterials. Macromol Biosci (2006) 6(8):623–33. doi:10.1002/mabi.200600069

PubMed Abstract | CrossRef Full Text | Google Scholar

108. Rebelatto MC, Guimond P, Bowersock TL, HogenEsch H. Induction of systemic and mucosal immune response in cattle by intranasal administration of pig serum albumin in alginate microparticles. Vet Immunol Immunopathol (2001) 83(1–2):93–105. doi:10.1016/S0165-2427(01)00370-1

PubMed Abstract | CrossRef Full Text | Google Scholar

109. Chadwick S, Kriegel C, Amiji M. Nanotechnology solutions for mucosal immunization. Adv Drug Deliv Rev (2010) 62(4–5):394–407. doi:10.1016/j.addr.2009.11.012

PubMed Abstract | CrossRef Full Text | Google Scholar

110. Read RC, Naylor SC, Potter CW, Bond J, Jabbal-Gill I, Fisher A, et al. Effective nasal influenza vaccine delivery using chitosan. Vaccine (2005) 23(35):4367–74. doi:10.1016/j.vaccine.2005.04.021

PubMed Abstract | CrossRef Full Text | Google Scholar

111. Filipovic-Grcic J, Skalko-Basnet N, Jalsenjak I. Mucoadhesive chitosan-coated liposomes: characteristics and stability. J Microencapsul (2001) 18(1):3–12. doi:10.1080/026520401750038557

PubMed Abstract | CrossRef Full Text | Google Scholar

112. Kobayashi T, Fukushima K, Sannan T, Saito N, Takiguchi Y, Sato Y, et al. Evaluation of the effectiveness and safety of chitosan derivatives as adjuvants for intranasal vaccines. Viral Immunol (2013) 26(2):133–42. doi:10.1089/vim.2012.0057

PubMed Abstract | CrossRef Full Text | Google Scholar

113. McKee AS, Marrack P. Old and new adjuvants. Curr Opin Immunol (2017) 47:44–51. doi:10.1016/j.coi.2017.06.005

PubMed Abstract | CrossRef Full Text | Google Scholar

114. Pizza M, Giuliani MM, Fontana MR, Monaci E, Douce G, Dougan G, et al. Mucosal vaccines: non toxic derivatives of LT and CT as mucosal adjuvants. Vaccine (2001) 19(17–19):2534–41. doi:10.1016/S0264-410X(00)00553-3

PubMed Abstract | CrossRef Full Text | Google Scholar

115. Fukuyama Y, Okada K, Yamaguchi M, Kiyono H, Mori K, Yuki Y. Nasal administration of cholera toxin as a mucosal adjuvant damages the olfactory system in mice. PLoS One (2015) 10(9):e0139368. doi:10.1371/journal.pone.0139368

PubMed Abstract | CrossRef Full Text | Google Scholar

116. Mutsch M, Zhou W, Rhodes P, Bopp M, Chen RT, Linder T, et al. Use of the inactivated intranasal influenza vaccine and the risk of Bell’s palsy in Switzerland. N Engl J Med (2004) 350(9):896–903. doi:10.1056/NEJMoa030595

PubMed Abstract | CrossRef Full Text | Google Scholar

117. Ryan EJ, McNeela E, Murphy GA, Stewart H, O’Hagan D, Pizza M, et al. Mutants of Escherichia coli heat-labile toxin act as effective mucosal adjuvants for nasal delivery of an acellular pertussis vaccine: differential effects of the nontoxic AB complex and enzyme activity on Th1 and Th2 cells. Infect Immun (1999) 67(12):6270–80.

PubMed Abstract | Google Scholar

118. Jakobsen H, Saeland E, Gizurarson S, Schulz D, Jonsdottir I. Intranasal immunization with pneumococcal polysaccharide conjugate vaccines protects mice against invasive pneumococcal infections. Infect Immun (1999) 67(8):4128–33.

PubMed Abstract | Google Scholar

119. Neidleman JA, Vajdy M, Ugozzoli M, Ott G, O’Hagan D. Genetically detoxified mutants of heat-labile enterotoxin from Escherichia coli are effective adjuvants for induction of cytotoxic T-cell responses against HIV-1 gag-p55. Immunology (2000) 101(1):154–60. doi:10.1046/j.1365-2567.2000.00090.x

PubMed Abstract | CrossRef Full Text | Google Scholar

120. Yamamoto S, Kiyono H, Yamamoto M, Imaoka K, Fujihashi K, Van Ginkel FW, et al. A nontoxic mutant of cholera toxin elicits Th2-type responses for enhanced mucosal immunity. Proc Natl Acad Sci U S A (1997) 94(10):5267–72. doi:10.1073/pnas.94.10.5267

PubMed Abstract | CrossRef Full Text | Google Scholar

121. Norton EB, Lawson LB, Freytag LC, Clements JD. Characterization of a mutant Escherichia coli heat-labile toxin, LT(R192G/L211A), as a safe and effective oral adjuvant. Clin Vaccine Immunol (2011) 18(4):546–51. doi:10.1128/CVI.00538-10

PubMed Abstract | CrossRef Full Text | Google Scholar

122. Norton EB, Bauer DL, Weldon WC, Oberste MS, Lawson LB, Clements JD. The novel adjuvant dmLT promotes dose sparing, mucosal immunity and longevity of antibody responses to the inactivated polio vaccine in a murine model. Vaccine (2015) 33(16):1909–15. doi:10.1016/j.vaccine.2015.02.069

PubMed Abstract | CrossRef Full Text | Google Scholar

123. Sjokvist Ottsjo L, Flach CF, Clements J, Holmgren J, Raghavan S. A double mutant heat-labile toxin from Escherichia coli, LT(R192G/L211A), is an effective mucosal adjuvant for vaccination against Helicobacter pylori infection. Infect Immun (2013) 81(5):1532–40. doi:10.1128/IAI.01407-12

PubMed Abstract | CrossRef Full Text | Google Scholar

124. Lebens M, Terrinoni M, Karlsson SL, Larena M, Gustafsson-Hedberg T, Kallgard S, et al. Construction and preclinical evaluation of mmCT, a novel mutant cholera toxin adjuvant that can be efficiently produced in genetically manipulated Vibrio cholerae. Vaccine (2016) 34(18):2121–8. doi:10.1016/j.vaccine.2016.03.002

PubMed Abstract | CrossRef Full Text | Google Scholar

125. Agren LC, Ekman L, Lowenadler B, Lycke NY. Genetically engineered nontoxic vaccine adjuvant that combines B cell targeting with immunomodulation by cholera toxin A1 subunit. J Immunol (1997) 158(8):3936–46.

PubMed Abstract | Google Scholar

126. Zaman M, Ozberk V, Langshaw EL, McPhun V, Powell JL, Phillips ZN, et al. Novel platform technology for modular mucosal vaccine that protects against Streptococcus. Sci Rep (2016) 6:39274. doi:10.1038/srep39274

PubMed Abstract | CrossRef Full Text | Google Scholar

127. McCluskie MJ, Davis HL. Oral, intrarectal and intranasal immunizations using CpG and non-CpG oligodeoxynucleotides as adjuvants. Vaccine (2000) 19(4–5):413–22. doi:10.1016/S0264-410X(00)00208-5

PubMed Abstract | CrossRef Full Text | Google Scholar

128. Boyaka PN, Marinaro M, Jackson RJ, van Ginkel FW, Cormet-Boyaka E, Kirk KL, et al. Oral QS-21 requires early IL-4 help for induction of mucosal and systemic immunity. J Immunol (2001) 166(4):2283–90. doi:10.4049/jimmunol.166.4.2283

PubMed Abstract | CrossRef Full Text | Google Scholar

129. Sasaki S, Sumino K, Hamajima K, Fukushima J, Ishii N, Kawamoto S, et al. Induction of systemic and mucosal immune responses to human immunodeficiency virus type 1 by a DNA vaccine formulated with QS-21 saponin adjuvant via intramuscular and intranasal routes. J Virol (1998) 72(6):4931–9.

PubMed Abstract | Google Scholar

130. Wang N, Wang T, Zhang M, Chen R, Niu R, Deng Y. Mannose derivative and lipid A dually decorated cationic liposomes as an effective cold chain free oral mucosal vaccine adjuvant-delivery system. Eur J Pharm Biopharm (2014) 88(1):194–206. doi:10.1016/j.ejpb.2014.04.007

PubMed Abstract | CrossRef Full Text | Google Scholar

131. Iho S, Maeyama J, Suzuki F. CpG oligodeoxynucleotides as mucosal adjuvants. Hum Vaccin Immunother (2015) 11(3):755–60. doi:10.1080/21645515.2014.1004033

PubMed Abstract | CrossRef Full Text | Google Scholar

132. Todoroff J, Lemaire MM, Fillee C, Jurion F, Renauld JC, Huygen K, et al. Mucosal and systemic immune responses to Mycobacterium tuberculosis antigen 85A following its co-delivery with CpG, MPLA or LTB to the lungs in mice. PLoS One (2013) 8(5):e63344. doi:10.1371/journal.pone.0063344

PubMed Abstract | CrossRef Full Text | Google Scholar

133. Van Maele L, Fougeron D, Janot L, Didierlaurent A, Cayet D, Tabareau J, et al. Airway structural cells regulate TLR5-mediated mucosal adjuvant activity. Mucosal Immunol (2014) 7(3):489–500. doi:10.1038/mi.2013.66

PubMed Abstract | CrossRef Full Text | Google Scholar

134. Hong SH, Byun YH, Nguyen CT, Kim SY, Seong BL, Park S, et al. Intranasal administration of a flagellin-adjuvanted inactivated influenza vaccine enhances mucosal immune responses to protect mice against lethal infection. Vaccine (2012) 30(2):466–74. doi:10.1016/j.vaccine.2011.10.058

PubMed Abstract | CrossRef Full Text | Google Scholar

135. Schoenen H, Bodendorfer B, Hitchens K, Manzanero S, Werninghaus K, Nimmerjahn F, et al. Cutting edge: mincle is essential for recognition and adjuvanticity of the mycobacterial cord factor and its synthetic analog trehalose-dibehenate. J Immunol (2010) 184(6):2756–60. doi:10.4049/jimmunol.0904013

PubMed Abstract | CrossRef Full Text | Google Scholar

136. Christensen D, Foged C, Rosenkrands I, Lundberg CV, Andersen P, Agger EM, et al. CAF01 liposomes as a mucosal vaccine adjuvant: in vitro and in vivo investigations. Int J Pharm (2010) 390(1):19–24. doi:10.1016/j.ijpharm.2009.10.043

PubMed Abstract | CrossRef Full Text | Google Scholar

137. Martin TL, Jee J, Kim E, Steiner HE, Cormet-Boyaka E, Boyaka PN. Sublingual targeting of STING with 3’3’-cGAMP promotes systemic and mucosal immunity against anthrax toxins. Vaccine (2017) 35(18):2511–9. doi:10.1016/j.vaccine.2017.02.064

PubMed Abstract | CrossRef Full Text | Google Scholar

138. Courtney AN, Nehete PN, Nehete BP, Thapa P, Zhou D, Sastry KJ. Alpha-galactosylceramide is an effective mucosal adjuvant for repeated intranasal or oral delivery of HIV peptide antigens. Vaccine (2009) 27(25–26):3335–41. doi:10.1016/j.vaccine.2009.01.083

PubMed Abstract | CrossRef Full Text | Google Scholar

139. Singh S, Nehete PN, Yang G, He H, Nehete B, Hanley PW, et al. Enhancement of mucosal immunogenicity of viral vectored vaccines by the NKT cell agonist alpha-galactosylceramide as adjuvant. Vaccines (Basel) (2014) 2(4):686–706. doi:10.3390/vaccines2040686

PubMed Abstract | CrossRef Full Text | Google Scholar

140. Pigny F, Lassus A, Terrettaz J, Tranquart F, Corthesy B, Bioley G. Intranasal vaccination with Salmonella-derived serodominant secreted effector protein B associated with gas-filled microbubbles partially protects against gut infection in mice. J Infect Dis (2016) 214(3):438–46. doi:10.1093/infdis/jiw162

PubMed Abstract | CrossRef Full Text | Google Scholar

141. Boks MA, Ambrosini M, Bruijns SC, Kalay H, van Bloois L, Storm G, et al. MPLA incorporation into DC-targeting glycoliposomes favours anti-tumour T cell responses. J Control Release (2015) 216:37–46. doi:10.1016/j.jconrel.2015.06.033

PubMed Abstract | CrossRef Full Text | Google Scholar

142. Lonez C, Bessodes M, Scherman D, Vandenbranden M, Escriou V, Ruysschaert JM. Cationic lipid nanocarriers activate toll-like receptor 2 and NLRP3 inflammasome pathways. Nanomedicine (2014) 10(4):775–82. doi:10.1016/j.nano.2013.12.003

PubMed Abstract | CrossRef Full Text | Google Scholar

143. Henriksen-Lacey M, Korsholm KS, Andersen P, Perrie Y, Christensen D. Liposomal vaccine delivery systems. Expert Opin Drug Deliv (2011) 8(4):505–19. doi:10.1517/17425247.2011.558081

PubMed Abstract | CrossRef Full Text | Google Scholar

144. Sessa G, Weissmann G. Phospholipid spherules (liposomes) as a model for biological membranes. J Lipid Res (1968) 9(3):310–8.

PubMed Abstract | Google Scholar

145. Watarai S, Han M, Tana, Kodama H. Antibody response in the intestinal tract of mice orally immunized with antigen associated with liposomes. J Vet Med Sci (1998) 60(9):1047–50. doi:10.1292/jvms.60.1047

PubMed Abstract | CrossRef Full Text | Google Scholar

146. Han M, Watarai S, Kobayashi K, Yasuda T. Application of liposomes for development of oral vaccines: study of in vitro stability of liposomes and antibody response to antigen associated with liposomes after oral immunization. J Vet Med Sci (1997) 59(12):1109–14. doi:10.1292/jvms.59.1109

PubMed Abstract | CrossRef Full Text | Google Scholar

147. Drummond DC, Zignani M, Leroux J. Current status of pH-sensitive liposomes in drug delivery. Prog Lipid Res (2000) 39(5):409–60. doi:10.1016/S0163-7827(00)00011-4

CrossRef Full Text | Google Scholar

148. Nair S, Zhou F, Reddy R, Huang L, Rouse BT. Soluble proteins delivered to dendritic cells via pH-sensitive liposomes induce primary cytotoxic T lymphocyte responses in vitro. J Exp Med (1992) 175(2):609–12. doi:10.1084/jem.175.2.609

PubMed Abstract | CrossRef Full Text | Google Scholar

149. Yusuf H, Ali AA, Orr N, Tunney MM, McCarthy HO, Kett VL. Novel freeze-dried DDA and TPGS liposomes are suitable for nasal delivery of vaccine. Int J Pharm (2017) 533(1):179–86. doi:10.1016/j.ijpharm.2017.09.011

PubMed Abstract | CrossRef Full Text | Google Scholar

150. Tada R, Hidaka A, Iwase N, Takahashi S, Yamakita Y, Iwata T, et al. Intranasal immunization with DOTAP cationic liposomes combined with DC-cholesterol induces potent antigen-specific mucosal and systemic immune responses in mice. PLoS One (2015) 10(10):e0139785. doi:10.1371/journal.pone.0139785

PubMed Abstract | CrossRef Full Text | Google Scholar

151. Agger EM, Rosenkrands I, Hansen J, Brahimi K, Vandahl BS, Aagaard C, et al. Cationic liposomes formulated with synthetic mycobacterial cordfactor (CAF01): a versatile adjuvant for vaccines with different immunological requirements. PLoS One (2008) 3(9):e3116. doi:10.1371/journal.pone.0003116

PubMed Abstract | CrossRef Full Text | Google Scholar

152. Davidsen J, Rosenkrands I, Christensen D, Vangala A, Kirby D, Perrie Y, et al. Characterization of cationic liposomes based on dimethyldioctadecylammonium and synthetic cord factor from M. tuberculosis (trehalose 6,6’-dibehenate) – a novel adjuvant inducing both strong CMI and antibody responses. Biochim Biophys Acta (2005) 1718(1–2):22–31. doi:10.1016/j.bbamem.2005.10.011

PubMed Abstract | CrossRef Full Text | Google Scholar

153. Mortensen R, Christensen D, Hansen LB, Christensen JP, Andersen P, Dietrich J. Local Th17/IgA immunity correlate with protection against intranasal infection with Streptococcus pyogenes. PLoS One (2017) 12(4):e0175707. doi:10.1371/journal.pone.0175707

PubMed Abstract | CrossRef Full Text | Google Scholar

154. Joseph A, Itskovitz-Cooper N, Samira S, Flasterstein O, Eliyahu H, Simberg D, et al. A new intranasal influenza vaccine based on a novel polycationic lipid – ceramide carbamoyl-spermine (CCS) I. Immunogenicity and efficacy studies in mice. Vaccine (2006) 24(18):3990–4006. doi:10.1016/j.vaccine.2005.12.017

CrossRef Full Text | Google Scholar

155. Rosada RS, de la Torre LG, Frantz FG, Trombone AP, Zarate-Blades CR, Fonseca DM, et al. Protection against tuberculosis by a single intranasal administration of DNA-hsp65 vaccine complexed with cationic liposomes. BMC Immunol (2008) 9:38. doi:10.1186/1471-2172-9-38

PubMed Abstract | CrossRef Full Text | Google Scholar

156. Harde H, Agrawal AK, Jain S. Tetanus toxoid-loaded layer-by-layer nanoassemblies for efficient systemic, mucosal, and cellular immunostimulatory response following oral administration. Drug Deliv Transl Res (2015) 5(5):498–510. doi:10.1007/s13346-015-0247-x

PubMed Abstract | CrossRef Full Text | Google Scholar

157. Mahale NB, Thakkar PD, Mali RG, Walunj DR, Chaudhari SR. Niosomes: novel sustained release nonionic stable vesicular systems – an overview. Adv Colloid Interface Sci (2012) 183-184:46–54. doi:10.1016/j.cis.2012.08.002

CrossRef Full Text | Google Scholar

158. Jain S, Vyas SP. Mannosylated niosomes as carrier adjuvant system for topical immunization. J Pharm Pharmacol (2005) 57(9):1177–84. doi:10.1211/jpp.57.9.0012

PubMed Abstract | CrossRef Full Text | Google Scholar

159. Conacher M, Alexander J, Brewer JM. Oral immunisation with peptide and protein antigens by formulation in lipid vesicles incorporating bile salts (bilosomes). Vaccine (2001) 19(20–22):2965–74. doi:10.1016/S0264-410X(00)00537-5

PubMed Abstract | CrossRef Full Text | Google Scholar

160. Shukla A, Mishra V, Kesharwani P. Bilosomes in the context of oral immunization: development, challenges and opportunities. Drug Discov Today (2016) 21(6):888–99. doi:10.1016/j.drudis.2016.03.013

PubMed Abstract | CrossRef Full Text | Google Scholar

161. Holm R, Mullertz A, Mu H. Bile salts and their importance for drug absorption. Int J Pharm (2013) 453(1):44–55. doi:10.1016/j.ijpharm.2013.04.003

PubMed Abstract | CrossRef Full Text | Google Scholar

162. Shukla A, Singh B, Katare OP. Significant systemic and mucosal immune response induced on oral delivery of diphtheria toxoid using nano-bilosomes. Br J Pharmacol (2011) 164(2b):820–7. doi:10.1111/j.1476-5381.2011.01452.x

PubMed Abstract | CrossRef Full Text | Google Scholar

163. Mann JF, Scales HE, Shakir E, Alexander J, Carter KC, Mullen AB, et al. Oral delivery of tetanus toxoid using vesicles containing bile salts (bilosomes) induces significant systemic and mucosal immunity. Methods (2006) 38(2):90–5. doi:10.1016/j.ymeth.2005.11.002

PubMed Abstract | CrossRef Full Text | Google Scholar

164. Jain S, Harde H, Indulkar A, Agrawal AK. Improved stability and immunological potential of tetanus toxoid containing surface engineered bilosomes following oral administration. Nanomedicine (2014) 10(2):431–40. doi:10.1016/j.nano.2013.08.012

PubMed Abstract | CrossRef Full Text | Google Scholar

165. Patel GB, Chen W. Archaeal lipid mucosal vaccine adjuvant and delivery system. Expert Rev Vaccines (2010) 9(4):431–40. doi:10.1586/erv.10.34

PubMed Abstract | CrossRef Full Text | Google Scholar

166. Conlan JW, Krishnan L, Willick GE, Patel GB, Sprott GD. Immunization of mice with lipopeptide antigens encapsulated in novel liposomes prepared from the polar lipids of various archaebacteria elicits rapid and prolonged specific protective immunity against infection with the facultative intracellular pathogen, Listeria monocytogenes. Vaccine (2001) 19(25–26):3509–17.

Google Scholar

167. Patel GB, Zhou H, Ponce A, Chen W. Mucosal and systemic immune responses by intranasal immunization using archaeal lipid-adjuvanted vaccines. Vaccine (2007) 25(51):8622–36. doi:10.1016/j.vaccine.2007.09.042

PubMed Abstract | CrossRef Full Text | Google Scholar

168. Patel GB, Zhou H, Ponce A, Harris G, Chen W. Intranasal immunization with an archaeal lipid mucosal vaccine adjuvant and delivery formulation protects against a respiratory pathogen challenge. PLoS One (2010) 5(12):e15574. doi:10.1371/journal.pone.0015574

PubMed Abstract | CrossRef Full Text | Google Scholar

169. Li Z, Zhang L, Sun W, Ding Q, Hou Y, Xu Y. Archaeosomes with encapsulated antigens for oral vaccine delivery. Vaccine (2011) 29(32):5260–6. doi:10.1016/j.vaccine.2011.05.015

PubMed Abstract | CrossRef Full Text | Google Scholar

170. Felnerova D, Viret JF, Gluck R, Moser C. Liposomes and virosomes as delivery systems for antigens, nucleic acids and drugs. Curr Opin Biotechnol (2004) 15(6):518–29. doi:10.1016/j.copbio.2004.10.005

PubMed Abstract | CrossRef Full Text | Google Scholar

171. Moser C, Amacker M, Kammer AR, Rasi S, Westerfeld N, Zurbriggen R. Influenza virosomes as a combined vaccine carrier and adjuvant system for prophylactic and therapeutic immunizations. Expert Rev Vaccines (2007) 6(5):711–21. doi:10.1586/14760584.6.5.711

PubMed Abstract | CrossRef Full Text | Google Scholar

172. Madhun AS, Haaheim LR, Nilsen MV, Cox RJ. Intramuscular matrix-M-adjuvanted virosomal H5N1 vaccine induces high frequencies of multifunctional Th1 CD4+ cells and strong antibody responses in mice. Vaccine (2009) 27(52):7367–76. doi:10.1016/j.vaccine.2009.09.044

PubMed Abstract | CrossRef Full Text | Google Scholar

173. Bomsel M, Tudor D, Drillet AS, Alfsen A, Ganor Y, Roger MG, et al. Immunization with HIV-1 gp41 subunit virosomes induces mucosal antibodies protecting nonhuman primates against vaginal SHIV challenges. Immunity (2011) 34(2):269–80. doi:10.1016/j.immuni.2011.01.015

PubMed Abstract | CrossRef Full Text | Google Scholar

174. Pedersen GK, Ebensen T, Gjeraker IH, Svindland S, Bredholt G, Guzman CA, et al. Evaluation of the sublingual route for administration of influenza H5N1 virosomes in combination with the bacterial second messenger c-di-GMP. PLoS One (2011) 6(11):e26973. doi:10.1371/journal.pone.0026973

PubMed Abstract | CrossRef Full Text | Google Scholar

175. Ebensen T, Debarry J, Pedersen GK, Blazejewska P, Weissmann S, Schulze K, et al. Mucosal administration of cycle-di-nucleotide-adjuvanted virosomes efficiently induces protection against influenza H5N1 in mice. Front Immunol (2017) 8:1223. doi:10.3389/fimmu.2017.01223

PubMed Abstract | CrossRef Full Text | Google Scholar

176. Shafique M, Meijerhof T, Wilschut J, de Haan A. Evaluation of an intranasal virosomal vaccine against respiratory syncytial virus in mice: effect of TLR2 and NOD2 ligands on induction of systemic and mucosal immune responses. PLoS One (2013) 8(4):e61287. doi:10.1371/journal.pone.0061287

PubMed Abstract | CrossRef Full Text | Google Scholar

177. Lindner JR. Microbubbles in medical imaging: current applications and future directions. Nat Rev Drug Discov (2004) 3(6):527–32. doi:10.1038/nrd1417

CrossRef Full Text | Google Scholar

178. Shapiro G, Wong AW, Bez M, Yang F, Tam S, Even L, et al. Multiparameter evaluation of in vivo gene delivery using ultrasound-guided, microbubble-enhanced sonoporation. J Control Release (2016) 223:157–64. doi:10.1016/j.jconrel.2015.12.001

PubMed Abstract | CrossRef Full Text | Google Scholar

179. Sennoga CA, Kanbar E, Auboire L, Dujardin PA, Fouan D, Escoffre JM, et al. Microbubble-mediated ultrasound drug-delivery and therapeutic monitoring. Expert Opin Drug Deliv (2017) 14(9):1031–43. doi:10.1080/17425247.2017.1266328

PubMed Abstract | CrossRef Full Text | Google Scholar

180. Oda Y, Suzuki R, Otake S, Nishiie N, Hirata K, Koshima R, et al. Prophylactic immunization with Bubble liposomes and ultrasound-treated dendritic cells provided a four-fold decrease in the frequency of melanoma lung metastasis. J Control Release (2012) 160(2):362–6. doi:10.1016/j.jconrel.2011.12.003

PubMed Abstract | CrossRef Full Text | Google Scholar

181. Bioley G, Bussat P, Lassus A, Schneider M, Terrettaz J, Corthesy B. The phagocytosis of gas-filled microbubbles by human and murine antigen-presenting cells. Biomaterials (2012) 33(1):333–42. doi:10.1016/j.biomaterials.2011.09.045

PubMed Abstract | CrossRef Full Text | Google Scholar

182. Bioley G, Lassus A, Bussat P, Terrettaz J, Tranquart F, Corthesy B. Gas-filled microbubble-mediated delivery of antigen and the induction of immune responses. Biomaterials (2012) 33(25):5935–46. doi:10.1016/j.biomaterials.2012.05.004

PubMed Abstract | CrossRef Full Text | Google Scholar

183. Bioley G, Zehn D, Lassus A, Terrettaz J, Tranquart F, Corthesy B. The effect of vaccines based on ovalbumin coupled to gas-filled microbubbles for reducing infection by ovalbumin-expressing Listeria monocytogenes. Biomaterials (2013) 34(21):5423–30. doi:10.1016/j.biomaterials.2013.04.005

PubMed Abstract | CrossRef Full Text | Google Scholar

184. Bioley G, Lassus A, Terrettaz J, Tranquart F, Corthesy B. Long-term persistence of immunity induced by OVA-coupled gas-filled microbubble vaccination partially protects mice against infection by OVA-expressing Listeria. Biomaterials (2015) 57:153–60. doi:10.1016/j.biomaterials.2015.04.008

PubMed Abstract | CrossRef Full Text | Google Scholar

185. Wu W, Wang Y, Shen S, Wu J, Guo S, Su L, et al. In vivo ultrasound molecular imaging of inflammatory thrombosis in arteries with cyclic Arg-Gly-Asp-modified microbubbles targeted to glycoprotein IIb/IIIa. Invest Radiol (2013) 48(11):803–12. doi:10.1097/RLI.0b013e318298652d

PubMed Abstract | CrossRef Full Text | Google Scholar

186. Bettinger T, Bussat P, Tardy I, Pochon S, Hyvelin JM, Emmel P, et al. Ultrasound molecular imaging contrast agent binding to both E- and P-selectin in different species. Invest Radiol (2012) 47(9):516–23. doi:10.1097/RLI.0b013e31825cc605

PubMed Abstract | CrossRef Full Text | Google Scholar

187. Cavalli R, Soster M, Argenziano M. Nanobubbles: a promising efficient tool for therapeutic delivery. Ther Deliv (2016) 7(2):117–38. doi:10.4155/tde.15.92

PubMed Abstract | CrossRef Full Text | Google Scholar

188. Sun HX, Xie Y, Ye YP. ISCOMs and ISCOMATRIX. Vaccine (2009) 27(33):4388–401. doi:10.1016/j.vaccine.2009.05.032

PubMed Abstract | CrossRef Full Text | Google Scholar

189. Morelli AB, Becher D, Koernig S, Silva A, Drane D, Maraskovsky E. ISCOMATRIX: a novel adjuvant for use in prophylactic and therapeutic vaccines against infectious diseases. J Med Microbiol (2012) 61(Pt 7):935–43. doi:10.1099/jmm.0.040857-0

PubMed Abstract | CrossRef Full Text | Google Scholar

190. Wilson NS, Yang B, Morelli AB, Koernig S, Yang A, Loeser S, et al. ISCOMATRIX vaccines mediate CD8+ T-cell cross-priming by a MyD88-dependent signaling pathway. Immunol Cell Biol (2012) 90(5):540–52. doi:10.1038/icb.2011.71

PubMed Abstract | CrossRef Full Text | Google Scholar

191. Jones PD, Tha Hla R, Morein B, Lovgren K, Ada GL. Cellular immune responses in the murine lung to local immunization with influenza A virus glycoproteins in micelles and immunostimulatory complexes (iscoms). Scand J Immunol (1988) 27(6):645–52. doi:10.1111/j.1365-3083.1988.tb02397.x

PubMed Abstract | CrossRef Full Text | Google Scholar

192. Coulter A, Harris R, Davis R, Drane D, Cox J, Ryan D, et al. Intranasal vaccination with ISCOMATRIX adjuvanted influenza vaccine. Vaccine (2003) 21(9–10):946–9. doi:10.1016/S0264-410X(02)00545-5

PubMed Abstract | CrossRef Full Text | Google Scholar

193. Wee JL, Scheerlinck JP, Snibson KJ, Edwards S, Pearse M, Quinn C, et al. Pulmonary delivery of ISCOMATRIX influenza vaccine induces both systemic and mucosal immunity with antigen dose sparing. Mucosal Immunol (2008) 1(6):489–96. doi:10.1038/mi.2008.59

PubMed Abstract | CrossRef Full Text | Google Scholar

194. Vujanic A, Wee JL, Snibson KJ, Edwards S, Pearse M, Quinn C, et al. Combined mucosal and systemic immunity following pulmonary delivery of ISCOMATRIX adjuvanted recombinant antigens. Vaccine (2010) 28(14):2593–7. doi:10.1016/j.vaccine.2010.01.018

PubMed Abstract | CrossRef Full Text | Google Scholar

195. Trudel M, Nadon F, Seguin C, Brault S, Lusignan Y, Lemieux S. Initiation of cytotoxic T-cell response and protection of Balb/c mice by vaccination with an experimental ISCOMs respiratory syncytial virus subunit vaccine. Vaccine (1992) 10(2):107–12. doi:10.1016/0264-410X(92)90026-G

PubMed Abstract | CrossRef Full Text | Google Scholar

196. Pandey RS, Dixit VK. Evaluation of ISCOM vaccines for mucosal immunization against hepatitis B. J Drug Target (2010) 18(4):282–91. doi:10.3109/10611860903450015

PubMed Abstract | CrossRef Full Text | Google Scholar

197. Hsu SC, Schadeck EB, Delmas A, Shaw M, Steward MW. Linkage of a fusion peptide to a CTL epitope from the nucleoprotein of measles virus enables incorporation into ISCOMs and induction of CTL responses following intranasal immunization. Vaccine (1996) 14(12):1159–66. doi:10.1016/0264-410X(95)00241-R

PubMed Abstract | CrossRef Full Text | Google Scholar

198. Lovgren K, Kaberg H, Morein B. An experimental influenza subunit vaccine (iscom): induction of protective immunity to challenge infection in mice after intranasal or subcutaneous administration. Clin Exp Immunol (1990) 82(3):435–9. doi:10.1111/j.1365-2249.1990.tb05467.x

PubMed Abstract | CrossRef Full Text | Google Scholar

199. Andersen CS, Dietrich J, Agger EM, Lycke NY, Lovgren K, Andersen P. The combined CTA1-DD/ISCOMs vector is an effective intranasal adjuvant for boosting prior Mycobacterium bovis BCG immunity to Mycobacterium tuberculosis. Infect Immun (2007) 75(1):408–16. doi:10.1128/IAI.01290-06

PubMed Abstract | CrossRef Full Text | Google Scholar

200. Eliasson DG, Helgeby A, Schon K, Nygren C, El-Bakkouri K, Fiers W, et al. A novel non-toxic combined CTA1-DD and ISCOMS adjuvant vector for effective mucosal immunization against influenza virus. Vaccine (2011) 29(23):3951–61. doi:10.1016/j.vaccine.2011.03.090

PubMed Abstract | CrossRef Full Text | Google Scholar

201. Skene CD, Doidge C, Sutton P. Evaluation of ISCOMATRIX and ISCOM vaccines for immunisation against Helicobacter pylori. Vaccine (2008) 26(31):3880–4. doi:10.1016/j.vaccine.2008.05.004

PubMed Abstract | CrossRef Full Text | Google Scholar

202. Sjolander A, Drane D, Maraskovsky E, Scheerlinck JP, Suhrbier A, Tennent J, et al. Immune responses to ISCOM formulations in animal and primate models. Vaccine (2001) 19(17–19):2661–5. doi:10.1016/S0264-410X(00)00497-7

PubMed Abstract | CrossRef Full Text | Google Scholar

203. Cibulski SP, Mourglia-Ettlin G, Teixeira TF, Quirici L, Roehe PM, Ferreira F, et al. Novel ISCOMs from Quillaja brasiliensis saponins induce mucosal and systemic antibody production, T-cell responses and improved antigen uptake. Vaccine (2016) 34(9):1162–71. doi:10.1016/j.vaccine.2016.01.029

PubMed Abstract | CrossRef Full Text | Google Scholar

204. Kodama S, Hirano T, Noda K, Umemoto S, Suzuki M. Nasal immunization with plasmid DNA encoding P6 protein and immunostimulatory complexes elicits nontypeable Haemophilus influenzae-specific long-term mucosal immune responses in the nasopharynx. Vaccine (2011) 29(10):1881–90. doi:10.1016/j.vaccine.2010.12.129

PubMed Abstract | CrossRef Full Text | Google Scholar

205. Kazanji M, Laurent F, Pery P. Immune responses and protective effect in mice vaccinated orally with surface sporozoite protein of Eimeria falciformis in ISCOMs. Vaccine (1994) 12(9):798–804. doi:10.1016/0264-410X(94)90288-7

PubMed Abstract | CrossRef Full Text | Google Scholar

206. Ghazi HO, Erturk M, Stannard LM, Faulkner M, Potter CW, Jennings R. Immunogenicity of influenza and HSV-1 mixed antigen ISCOMs in mice. Arch Virol (1995) 140(6):1015–31. doi:10.1007/BF01315412

PubMed Abstract | CrossRef Full Text | Google Scholar

207. Aguila A, Donachie AM, Peyre M, McSharry CP, Sesardic D, Mowat AM. Induction of protective and mucosal immunity against diphtheria by a immune stimulating complex (ISCOMS) based vaccine. Vaccine (2006) 24(24):5201–10. doi:10.1016/j.vaccine.2006.03.081

PubMed Abstract | CrossRef Full Text | Google Scholar

208. Helgeby A, Robson NC, Donachie AM, Beackock-Sharp H, Lovgren K, Schon K, et al. The combined CTA1-DD/ISCOM adjuvant vector promotes priming of mucosal and systemic immunity to incorporated antigens by specific targeting of B cells. J Immunol (2006) 176(6):3697–706. doi:10.4049/jimmunol.176.6.3697

PubMed Abstract | CrossRef Full Text | Google Scholar

209. Mowat AM, Donachie AM, Jagewall S, Schon K, Lowenadler B, Dalsgaard K, et al. CTA1-DD-immune stimulating complexes: a novel, rationally designed combined mucosal vaccine adjuvant effective with nanogram doses of antigen. J Immunol (2001) 167(6):3398–405. doi:10.4049/jimmunol.167.6.3398

PubMed Abstract | CrossRef Full Text | Google Scholar

210. Makidon PE, Belyakov IM, Blanco LP, Janczak KW, Landers J, Bielinska AU, et al. Nanoemulsion mucosal adjuvant uniquely activates cytokine production by nasal ciliated epithelium and induces dendritic cell trafficking. Eur J Immunol (2012) 42(8):2073–86. doi:10.1002/eji.201142346

PubMed Abstract | CrossRef Full Text | Google Scholar

211. Bielinska AU, Makidon PE, Janczak KW, Blanco LP, Swanson B, Smith DM, et al. Distinct pathways of humoral and cellular immunity induced with the mucosal administration of a nanoemulsion adjuvant. J Immunol (2014) 192(6):2722–33. doi:10.4049/jimmunol.1301424

PubMed Abstract | CrossRef Full Text | Google Scholar

212. Ahmed M, Smith DM, Hamouda T, Rangel-Moreno J, Fattom A, Khader SA. A novel nanoemulsion vaccine induces mucosal Interleukin-17 responses and confers protection upon Mycobacterium tuberculosis challenge in mice. Vaccine (2017) 35(37):4983–9. doi:10.1016/j.vaccine.2017.07.073

PubMed Abstract | CrossRef Full Text | Google Scholar

213. Makidon PE, Bielinska AU, Nigavekar SS, Janczak KW, Knowlton J, Scott AJ, et al. Pre-clinical evaluation of a novel nanoemulsion-based hepatitis B mucosal vaccine. PLoS One (2008) 3(8):e2954. doi:10.1371/journal.pone.0002954

PubMed Abstract | CrossRef Full Text | Google Scholar

214. Shahiwala A, Amiji MM. Enhanced mucosal and systemic immune response with squalane oil-containing multiple emulsions upon intranasal and oral administration in mice. J Drug Target (2008) 16(4):302–10. doi:10.1080/10611860801900082

PubMed Abstract | CrossRef Full Text | Google Scholar

215. Olive C, Schulze K, Sun HK, Ebensen T, Horvath A, Toth I, et al. Enhanced protection against Streptococcus pyogenes infection by intranasal vaccination with a dual antigen component M protein/SfbI lipid core peptide vaccine formulation. Vaccine (2007) 25(10):1789–97. doi:10.1016/j.vaccine.2006.11.031

PubMed Abstract | CrossRef Full Text | Google Scholar

216. Schulze K, Ebensen T, Chandrudu S, Skwarczynski M, Toth I, Olive C, et al. Bivalent mucosal peptide vaccines administered using the LCP carrier system stimulate protective immune responses against Streptococcus pyogenes infection. Nanomedicine (2017) 13(8):2463–74. doi:10.1016/j.nano.2017.08.015

PubMed Abstract | CrossRef Full Text | Google Scholar

217. Ogra PL. Mucosal immune response to poliovirus vaccines in childhood. Rev Infect Dis (1984) 6(Suppl 2):S361–8. doi:10.1093/clinids/6.Supplement_2.S361

PubMed Abstract | CrossRef Full Text | Google Scholar

218. Beale AJ. Efficacy and safety of oral poliovirus vaccine and inactivated poliovirus vaccine. Pediatr Infect Dis J (1991) 10(12):970–2.

PubMed Abstract | Google Scholar

219. Onorato IM, Modlin JF, McBean AM, Thoms ML, Losonsky GA, Bernier RH. Mucosal immunity induced by enhance-potency inactivated and oral polio vaccines. J Infect Dis (1991) 163(1):1–6. doi:10.1093/infdis/163.1.1

PubMed Abstract | CrossRef Full Text | Google Scholar

220. Levine MM, Chen WH, Kaper JB, Lock M, Danzig L, Gurwith M. PaxVax CVD 103-HgR single-dose live oral cholera vaccine. Expert Rev Vaccines (2017) 16(3):197–213. doi:10.1080/14760584.2017.1291348

PubMed Abstract | CrossRef Full Text | Google Scholar

221. Perry RT, Plowe CV, Koumare B, Bougoudogo F, Kotloff KL, Losonsky GA, et al. A single dose of live oral cholera vaccine CVD 103-HgR is safe and immunogenic in HIV-infected and HIV-noninfected adults in Mali. Bull World Health Organ (1998) 76(1):63–71.

PubMed Abstract | Google Scholar

222. Davitt CJ, Lavelle EC. Delivery strategies to enhance oral vaccination against enteric infections. Adv Drug Deliv Rev (2015) 91:52–69. doi:10.1016/j.addr.2015.03.007

PubMed Abstract | CrossRef Full Text | Google Scholar

223. Viret JF, Favre D, Wegmuller B, Herzog C, Que JU, Cryz SJ Jr, et al. Mucosal and systemic immune responses in humans after primary and booster immunizations with orally administered invasive and noninvasive live attenuated bacteria. Infect Immun (1999) 67(7):3680–5.

PubMed Abstract | Google Scholar

224. Sundstrom P, Lundin SB, Nilsson LA, Quiding-Jarbrink M. Human IgA-secreting cells induced by intestinal, but not systemic, immunization respond to CCL25 (TECK) and CCL28 (MEC). Eur J Immunol (2008) 38(12):3327–38. doi:10.1002/eji.200838506

PubMed Abstract | CrossRef Full Text | Google Scholar

225. Kantele A, Kantele JM, Savilahti E, Westerholm M, Arvilommi H, Lazarovits A, et al. Homing potentials of circulating lymphocytes in humans depend on the site of activation: oral, but not parenteral, typhoid vaccination induces circulating antibody-secreting cells that all bear homing receptors directing them to the gut. J Immunol (1997) 158(2):574–9.

PubMed Abstract | Google Scholar

226. Kantele A, Hakkinen M, Moldoveanu Z, Lu A, Savilahti E, Alvarez RD, et al. Differences in immune responses induced by oral and rectal immunizations with Salmonella typhi Ty21a: evidence for compartmentalization within the common mucosal immune system in humans. Infect Immun (1998) 66(12):5630–5.

PubMed Abstract | Google Scholar

227. Belshe RB, Mendelman PM, Treanor J, King J, Gruber WC, Piedra P, et al. The efficacy of live attenuated, cold-adapted, trivalent, intranasal influenzavirus vaccine in children. N Engl J Med (1998) 338(20):1405–12. doi:10.1056/NEJM199805143382002

PubMed Abstract | CrossRef Full Text | Google Scholar

228. Ambrose CS, Luke C, Coelingh K. Current status of live attenuated influenza vaccine in the United States for seasonal and pandemic influenza. Influenza Other Respir Viruses (2008) 2(6):193–202. doi:10.1111/j.1750-2659.2008.00056.x

PubMed Abstract | CrossRef Full Text | Google Scholar

229. Zakay-Rones Z. Human influenza vaccines and assessment of immunogenicity. Expert Rev Vaccines (2010) 9(12):1423–39. doi:10.1586/erv.10.144

PubMed Abstract | CrossRef Full Text | Google Scholar

230. Alving CR, Beck Z, Matyas GR, Rao M. Liposomal adjuvants for human vaccines. Expert Opin Drug Deliv (2016) 13(6):807–16. doi:10.1517/17425247.2016.1151871

PubMed Abstract | CrossRef Full Text | Google Scholar

231. Stanberry LR, Simon JK, Johnson C, Robinson PL, Morry J, Flack MR, et al. Safety and immunogenicity of a novel nanoemulsion mucosal adjuvant W805EC combined with approved seasonal influenza antigens. Vaccine (2012) 30(2):307–16. doi:10.1016/j.vaccine.2011.10.094

PubMed Abstract | CrossRef Full Text | Google Scholar

232. Mymetics SA. (2018). Available from: https://www.mymetics.com/

Google Scholar

233. Drane D, Gittleson C, Boyle J, Maraskovsky E. ISCOMATRIX adjuvant for prophylactic and therapeutic vaccines. Expert Rev Vaccines (2007) 6(5):761–72. doi:10.1586/14760584.6.5.761

PubMed Abstract | CrossRef Full Text | Google Scholar

234. Moser C, Muller M, Kaeser MD, Weydemann U, Amacker M. Influenza virosomes as vaccine adjuvant and carrier system. Expert Rev Vaccines (2013) 12(7):779–91. doi:10.1586/14760584.2013.811195

PubMed Abstract | CrossRef Full Text | Google Scholar

235. Pedersen GK, Sjursen H, Nostbakken JK, Jul-Larsen A, Hoschler K, Cox RJ. Matrix M(TM) adjuvanted virosomal H5N1 vaccine induces balanced Th1/Th2 CD4(+) T cell responses in man. Hum Vaccin Immunother (2014) 10(8):2408–16. doi:10.4161/hv.29583

PubMed Abstract | CrossRef Full Text | Google Scholar

236. O’Hagan DT, Ott GS, De Gregorio E, Seubert A. The mechanism of action of MF59 – an innately attractive adjuvant formulation. Vaccine (2012) 30(29):4341–8. doi:10.1016/j.vaccine.2011.09.061

PubMed Abstract | CrossRef Full Text | Google Scholar

237. Garcon N, Morel S, Didierlaurent A, Descamps D, Wettendorff M, Van Mechelen M. Development of an AS04-adjuvanted HPV vaccine with the adjuvant system approach. BioDrugs (2011) 25(4):217–26. doi:10.2165/11591760-000000000-00000

PubMed Abstract | CrossRef Full Text | Google Scholar

238. Garcon N, Van Mechelen M. Recent clinical experience with vaccines using MPL- and QS-21-containing adjuvant systems. Expert Rev Vaccines (2011) 10(4):471–86. doi:10.1586/erv.11.29

PubMed Abstract | CrossRef Full Text | Google Scholar

239. Casares S, Brumeanu TD, Richie TL. The RTS,S malaria vaccine. Vaccine (2010) 28(31):4880–94. doi:10.1016/j.vaccine.2010.05.033

PubMed Abstract | CrossRef Full Text | Google Scholar

240. Lal H, Cunningham AL, Heineman TC. Adjuvanted herpes zoster subunit vaccine in older adults. N Engl J Med (2015) 373(16):1576–7. doi:10.1056/NEJMc1508392

CrossRef Full Text | Google Scholar

241. Frazer IH, Quinn M, Nicklin JL, Tan J, Perrin LC, Ng P, et al. Phase 1 study of HPV16-specific immunotherapy with E6E7 fusion protein and ISCOMATRIX adjuvant in women with cervical intraepithelial neoplasia. Vaccine (2004) 23(2):172–81. doi:10.1016/j.vaccine.2004.05.013

PubMed Abstract | CrossRef Full Text | Google Scholar

242. Anderson JS, Hoy J, Hillman R, Barnden M, Eu B, McKenzie A, et al. A randomized, placebo-controlled, dose-escalation study to determine the safety, tolerability, and immunogenicity of an HPV-16 therapeutic vaccine in HIV-positive participants with oncogenic HPV infection of the anus. J Acquir Immune Defic Syndr (2009) 52(3):371–81. doi:10.1097/QAI.0b013e3181b7354c

PubMed Abstract | CrossRef Full Text | Google Scholar

243. Drane D, Maraskovsky E, Gibson R, Mitchell S, Barnden M, Moskwa A, et al. Priming of CD4+ and CD8+ T cell responses using a HCV core ISCOMATRIX vaccine: a phase I study in healthy volunteers. Hum Vaccin (2009) 5(3):151–7. doi:10.4161/hv.5.3.6614

PubMed Abstract | CrossRef Full Text | Google Scholar

244. Pabst R. Mucosal vaccination by the intranasal route. Nose-associated lymphoid tissue (NALT) – structure, function and species differences. Vaccine (2015) 33(36):4406–13. doi:10.1016/j.vaccine.2015.07.022

PubMed Abstract | CrossRef Full Text | Google Scholar

245. Allam JP, Novak N. Immunological mechanisms of sublingual immunotherapy. Curr Opin Allergy Clin Immunol (2014) 14(6):564–9. doi:10.1097/ACI.0000000000000118

PubMed Abstract | CrossRef Full Text | Google Scholar

246. Bahamondez-Canas TF, Cui Z. Intranasal immunization with dry powder vaccines. Eur J Pharm Biopharm (2018) 122:167–75. doi:10.1016/j.ejpb.2017.11.001

CrossRef Full Text | Google Scholar

247. Passalacqua G, Canonica GW. Sublingual immunotherapy: focus on tablets. Ann Allergy Asthma Immunol (2015) 115(1):4–9. doi:10.1016/j.anai.2015.03.022

CrossRef Full Text | Google Scholar

Keywords: mucosal, vaccination, lipidic particles, delivery system, infections

Citation: Corthésy B and Bioley G (2018) Lipid-Based Particles: Versatile Delivery Systems for Mucosal Vaccination against Infection. Front. Immunol. 9:431. doi: 10.3389/fimmu.2018.00431

Received: 22 December 2017; Accepted: 19 February 2018;
Published: 07 March 2018

Edited by:

Rajko Reljic, St George’s, University of London, United Kingdom

Reviewed by:

Vijay Panchanathan, Perdana University, Malaysia
Beatrice Jahn-Schmid, Medizinische Universität Wien, Austria

Copyright: © 2018 Corthésy and Bioley. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Gilles Bioley, gilles.bioley@chuv.ch

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.