Role of PON2 in innate immune response in an acute infection model
Introduction
Pseudomonas aeruginosa (PAO1) is an opportunistic pathogen that causes a wide variety of acute infections in immune-compromised patients, as well as chronic respiratory infections in patients suffering from cystic fibrosis, cancer, and other chronic respiratory diseases [1]. To facilitate the establishment of infection, PAO1 produces cell-associated and extracellular virulence factors, which are regulated by quorum sensing (QS) [2]. QS is a mechanism wherein small diffusible molecules, specifically acyl homo serine lactones (AHL), are produced and detected by the organisms' surrounding molecules. As the number of bacteria increase, intracellular levels of AHLs achieve a threshold concentration, including the activation of targeted transcriptional regulators [3]. This process is well described for the formation of biofilm in chronic infection by PAO1 and 3OC12-HSL; a member of the AHL family is shown to be the primary QS molecule [4]. Biofilms typically display a marked resistance to antibiotic killing and therefore infections associated with biofilm-forming bacteria are difficult to eradicate [5]. 3OC12-HSL is shown to induce stress signaling in immune cells, reduce immune cell function, and improve bacterial survival. Hence, inactivation of this molecule or its effect on host cells is a therapeutic target for PAO1 associated disease.
Paraoxonases, a family of Ca2 +dependent esterases consisting of PON1, PON2 and PON3 [6], hydrolyze 3OC12-HSL [7]. The PON gene family is located on chromosome 6 in mice and on chromosome 7 in humans [8]. In humans, PON1 mRNA expression is limited to the lung and liver [8]. In contrast, hPON2 is ubiquitously expressed including kidney, liver, lung, placenta, small intestine, spleen, stomach, testis, and vascular cells. In humans, PON3 is restricted to the lung, liver, and kidney [8]. In addition, hPON1 and hPON3 are associated with HDL in the circulatory system whereas hPON2 protein is undetectable in HDL, LDL, or cell supernatants; it is, however, associated with intracellular membrane fractions [9]. A property shared by all PON proteins is the capacity to hydrolyze lactones [7]. In particular, AHLs have been identified as substrates common for all PON proteins, with PON2 exhibiting the highest specific activity [7].
Macrophages play a central role in response to extracellular and intracellular pathogens [10]. Our previous studies have shown that PON2 is expressed in this immune effector cell and plays an important role in macrophage function under chronic inflammatory conditions [11]. Based on this evidence, we hypothesized and tested whether PON2-def influences the innate immune response in an acute PAO1 infection model.
Section snippets
Animals
Male PON2-def mice on the C57BL6/J background and littermate controls, 8 to 10 weeks old, were used in all experiments. The Animal Research Committee at the University of California, Los Angeles approved all experiments.
Membrane-enriched tissue and cell homogenates
Wild type and PON2-def mice were injected intraperitoneally with 1.5 ml of a solution consisting of 3% thioglycollate broth. Three days later, macrophages were collected from the peritoneal cavity. Cells were homogenized on ice in 1 volume of 25 mM Tris, pH 7.4, containing 1 mM CaCl2
Quorum quenching is impaired in macrophages from PON2-def mice
Macrophages are vital immune cells that contribute to innate immune defense whose function influences the quality, duration, and magnitude of most inflammatory reactions [17]. PON2 is highly expressed in macrophages and has been shown to alter their activation state [18]. Therefore, we first evaluated the capacity of membrane extracts from PON2-def peritoneal macrophages to inactivate 3OC12-HSL. As shown in Fig. 1, PON2-def macrophage membrane lysates (Fig. 1A) as well as intact macrophages (
Discussion
PAO1 is ubiquitously present in the environment and is known to cause nosocomial infections. 3OC12-HSL, a quorum-sensing molecule secreted by PAO1, participates in bacterial colonization and inhibition of host immune response. Anti-quorum-sensing molecules are therapeutic targets for treating PAO1 associated diseases. PON2 has been shown to inactivate 3OC12-HSL in vitro. PON2 is expressed in immune cells; however, studies to date have only focused on the role of PON2 in atherosclerosis,
Conflict of interest statement
None.
Acknowledgments
We thank Yuen Lin Lee and Ani Shabazian for their expert technical assistance. This work was supported by the National Heart, Lung and Blood Institute grant 1RO1HL71776 (S.T.R).
References (35)
- et al.
Quorum sensing and the regulation of virulence gene expression in pathogenic bacteria
Int. J. Med. Microbiol.
(2001) - et al.
Paraoxonases 1, 2, and 3, oxidative stress, and macrophage foam cell formation during atherosclerosis development
Free Radic. Biol. Med.
(2004) - et al.
Human paraoxonases (PON1, PON2, and PON3) are lactonases with overlapping and distinct substrate specificities
J. Lipid Res.
(2005) - et al.
The paraoxonase gene family and atherosclerosis
Free Radic. Biol. Med.
(2005) - et al.
Mitochondrial reactive oxygen species in mice lacking superoxide dismutase 2 — Attenuation via antioxidant treatment
J. Biol. Chem.
(2006) - et al.
Paraoxonase-2 is a ubiquitously expressed protein with antioxidant properties and is capable of preventing cell-mediated oxidative modification of low density lipoprotein
J. Biol. Chem.
(2001) - et al.
Paraoxonase-2 deficiency aggravates atherosclerosis in mice despite lower apolipoprotein-B-containing lipoproteins — anti-atherogenic role for paraoxonase-2
J. Biol. Chem.
(2006) - et al.
Pseudomonas aeruginosa quorum sensing molecule N-(3 oxododecanoyl)-l-homoserine lactone disrupts epithelial barrier integrity of Caco-2 cells
FEBS Lett.
(2006) - et al.
Macrophage paraoxonase 2 regulates calcium homeostasis and cell survival under endoplasmic reticulum stress conditions and is sufficient to prevent the development of aggravated atherosclerosis in paraoxonase 2 deficiency/apoE −/− mice on a Western diet
Mol. Genet. Metab.
(2012) - et al.
Antioxidants preserve macrophage phagocytosis of Pseudomonas aeruginosa during hyperoxia
Free Radic. Biol. Med.
(2007)
Human and murine paraoxonase 1 are host modulators of Pseudomonas aeruginosa quorum-sensing
FEMS Microbiol. Lett.
Paraoxonase 2 acts as a quorum sensing-quenching factor in human keratinocytes
J. Investig. Dermatol.
Regulation of gene expression by cell-to-cell communication: acyl-homoserine lactone quorum sensing
Annu. Rev. Genet.
Quorum sensing in bacteria
Annu. Rev. Microbiol.
Listening in on bacteria: acyl-homoserine lactone signalling
Nat. Rev. Mol. Cell Biol.
Pseudomonas aeruginosa tssC1 links type vi secretion and biofilm-specific antibiotic resistance
J. Bacteriol.
Is it just paraoxonase 1 or are other members of the paraoxonase gene family implicated in atherosclerosis?
Curr. Opin. Lipidol.
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- 1
Present address: Eulerstrasse 64, 4051 Basel, Switzerland.
- 2
Present address: Department of Pathology and Lab Medicine, University of California at Los Angeles, Los Angeles, CA 90095, USA.
- 3
Present address: Shanti Clinical Trials (1880 East Washington St. Suite-A, Colton, CA 92324, USA.