Mannan-binding lectin-associated serine protease-2 (MASP-2) in a large cohort of neonates and its clinical associations
Introduction
Four collagen-related lectins, mannan-binding (or mannose-binding) lectin (MBL), a collectin, and three ficolins: M (ficolin-1), L (ficolin-2) and H (ficolin-3, Hakata antigen) share the capacity to activate the complement system via the lectin pathway (reviewed by Thiel, 2007). This property is presumably an important mechanism of the innate immune defence. It depends on the unique ability of the afore-mentioned lectins to form complexes with MBL-associated serine proteases (MASPs), via the collagen region. None of the other known collectins (surfactant protein (SP)-A, SP-D, CL-P1, CL-K1, CL-L1, conglutinin, etc.) binds MASPs in spite of the structural similarities to MBL (Kilpatrick, 2007).
The MASP family consists of three enzymes (MASP-1, -2, and -3) and MAp-19 (MBL-associated protein of 19 kDa, also called sMAP, small MBL-associated protein), a truncated form of MASP-2 lacking enzymatic activity. The three MASPs have an identical domain organization, which is also the same as that of the two classical complement pathway serine proteases, C1r and C1s. All possess six domains (CUB1, EGF, CUB2, CCP1, CCP2 and a serine protease domain). When not activated (zymogens), they exist as single polypeptide chains, while after activation, they are converted into two chains, connected via a disulphide bond. The light chain is the serine protease domain, the heavy chain is comprised of the remaining domains. MASP-2 is believed to play a crucial role in the initiation of lectin pathway activation, cleaving C4 and C2, with high efficiency (Matsushita et al., 2000, Thiel et al., 2000, Rossi et al., 2001, Hajela et al., 2002, Gal et al., 2007, Duncan et al., 2008). After binding of MBL- or ficolin-MASP complex to the target structure, it undergoes autoactivation (Gal et al., 2005). Recently, the co-operation between MASP-2 and MASP-1 in complement activation was reported by Moller-Kristensen et al. (2007) and Takahashi et al. (2008).
Moreover, MASP-2 recognizes a serpin, the C1-inhibitor, therefore the latter is a pseudo-substrate and regulator of the lectin pathway (Petersen et al., 2000, Rossi et al., 2001, Presanis et al., 2004, Kerr et al., 2008). It was demonstrated that MAp19 (a product of alternative splicing of the MASP2 gene, consisting of identical CUB1 and EGF domains followed by C-terminal tetrapeptide) plays a regulatory role as well, by competitive binding to lectins (Iwaki et al., 2006, Gal et al., 2007), although very recent data have failed to confirm those findings (J.C. Jensenius, unpublished data). Moreover, it was demonstrated that MASP-2 may participate in the activation of the coagulation system, by recognising and cleaving prothrombin (Krarup et al., 2007).
The average concentration of MASP-2 released from the complexes with MBL or ficolins in Danish blood donors was determined as 534 ng/ml (Moller-Kristensen et al., 2003). A significant increase in its serum level was observed during the first 6 months of life (Schlapbach et al., 2008). Nine MASP2 gene polymorphisms in various populations were described, including C359A > G SNP, resulting in an exchange of aspartic acid for glycine at position 120 of the MASP-2 CUB1 domain (D120G) (105th residue of a mature protein, D105G). This SNP was shown to occur in Caucasians (Stengaard-Pedersen et al., 2003, Thiel et al., 2007), with a frequency of 3.9% (Thiel et al., 2007). Homozygosity for this variant allele, however, was estimated to occur as rarely as 6 cases per 10,000 individuals (Garcia-Laorden et al., 2008).
The current knowledge about disease-association of MASP-2, especially in neonates is very limited. Recently, Schlapbach et al. (2008) reported higher levels in the cord sera of babies developing necrotising enterocolitis. In a previous study (Swierzko et al., 2009), we investigated the associations of MBL and L-ficolin deficiencies with prematurity, low birthweight and increased susceptibility to perinatal infections in a large, ethnically homogeneous cohort of neonates. Now, to extend knowledge concerning the role of lectin pathway factors in neonatal immune defence, we report MASP-2 concentrations and genotypes in the same group.
Section snippets
Cord blood samples and population characteristics
Umbilical cord blood samples were consecutively collected from the Department of Neonatology of Gdansk Medical University and Poznan University of Medical Sciences, Poland. The agreement of the local ethical committees as well as written maternal informed consent were obtained. Sera and DNA samples were prepared and stored frozen until analysed. When samples were obtained from twin (19 sets) or multiple (2 triplets) pregnancies, only one sibling sample from each family was used for this study.
General data
Cord serum samples were analysed to determine MASP-2 concentrations. Values ranged from ≤25 to 812 ng/ml (median 93 ng/ml). A majority of babies had MASP-2 levels below 300 ng/ml (95th percentile was equal 289 ng/ml). Twenty-nine serum samples were also tested by a commercial MASP-2 kit (Hycult) with a high concordance between the two methods (r = 0.82; p < 0.00001). The MASP-2 concentrations within our cohort did not follow a normal distribution (p < 0.01; Fig. 1), also after logarithmic transformation (
Discussion
The MASP2, MBL2 and FCN2 genes are found on human chromosomes 1, 10 and 9, respectively. Their gene products combine to have a major influence on our ability to activate the lectin pathway of complement. Previously, we investigated L-ficolin and MBL in this cohort of Polish neonates (Swierzko et al., 2009). Here we have extended those studies to MASP-2.
Synthesis of complement factors starts as early as in the first trimester of pregnancy (reviewed by Kemp and Campbell, 1997) but the activities
Acknowledgements
This study was partially supported by Ministry of Science and Higher Education (Poland), grant 2 P05E 011 28. We are grateful for the support of the Royal Society of Edinburgh International Exchange Programme.
References (30)
- et al.
The initiating proteases of the complement system: controlling the cleavage
Biochimie
(2008) - et al.
Serine proteases of the classical and lectin pathways: similarities and differences
Immunobiology
(2007) - et al.
A true autoactivating enzyme. Structural insight into mannose-binding lectin-associated serine protease-2 activations
J. Biol. Chem.
(2005) - et al.
Low clinical penetrance of mannose-binding lectin-associated serine protease 2 deficiency
J. Allergy Clin. Immunol.
(2006) - et al.
The biological functions of MBL-associated serine proteases (MASPs)
Immunobiology
(2002) - et al.
Elucidation of the substrate specificity of the MASP-2 protease of the lectin complement pathway and identification of the enzyme as a major physiological target of the serpin, C1-inhibitor
Mol. Immunol.
(2008) - et al.
Heterogeneity of MBL-MASP complexes
Mol. Immunol.
(2006) - et al.
Levels of mannan-binding lectin-associated serine protease 2 in healthy individuals
J. Immunol. Methods
(2003) - et al.
Control of the classical and the MBL pathway of complement activation
Mol. Immunol.
(2000) - et al.
Differential substrate and inhibitor profiles for human MASP-1 and MASP-2
Mol. Immunol.
(2004)
Substrate specificities of recombinant mannan-binding lectin-associated serine proteases-1 and -2
J. Biol. Chem.
Complement activating soluble pattern recognition molecules with collagen-like regions, mannan-binding lectin, ficolins and associated serine proteases
Mol. Immunol.
Mannan-binding lectin insufficiency in children with recurrent infections of the respiratory system
Clin. Exp. Immunol.
A reagent for single-step simultaneous isolation of RNA, DNA and proteins from cell and tissue samples
Biotechniques
Mannose-binding lectin and mannose-binding lectin–associated serine protease 2 in susceptibility, severity, and outcome of pneumonia in adults
J. Allergy Clin. Immunol.
Cited by (28)
Complement deficiencies
2021, Inborn Errors of Immunity: A Practical GuideAssociation between MASP-2 gene polymorphism and risk of infection diseases: A meta-analysis
2016, Microbial PathogenesisCitation Excerpt :There is no mutation in the masp-2 gene (p.D120G, rs72550870) in Chinese [7]. Finally, a total of 9 studies were included in our meta-analysis [9–17], consisting of 1997 cases and 1895 controls. The study population came from two groups respectively based on the included articles: Latin America population (Brazil) and European population (Poland, Spain and Italy).
Distinct mechanisms of the newborn innate immunity
2016, Immunology LettersComponents of the lectin pathway of complement activation in paediatric patients of intensive care units
2016, ImmunobiologyCitation Excerpt :Sera were prepared from blood samples collected into tubes without anticoagulant and stored at −70 °C until testing. Single nucleotide polymorphisms of the MBL2 (Bak-Romaniszyn et al., 2011), MASP2 (Swierzko et al., 2009b), FCN2 (Szala et al., 2013) and FCN3 (Michalski et al., 2012) genes were analyzed essentially as previously described. Since, as mentioned, 225 previously investigated subjects were included in the control group, some of our earlier data were used for analyses: MBL2 and FCN2 genotypes have been previously determined in all mentioned newborns (Swierzko et al., 2009a,c; Kilpatrick et al., 2013), while MASP2 (Swierzko et al., 2009b and FCN3 genotypes (Michalski et al., 2012) were assessed in 105 and 17 babies, respectively.
Molecular cloning and characterization of a C-type lectin in roughskin sculpin (Trachidermus fasciatus)
2013, Fish and Shellfish Immunology