Secretory IgA is Concentrated in the Outer Layer of Colonic Mucus along with Gut Bacteria
1
Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington, KY 40536, USA
2
Current address: Centers for Disease Control and Prevention, Division of Parasitic Diseases and Malaria, Malaria Branch, Atlanta, GA 30333, USA
3
Current address: Division of Liberal Arts & Life Sciences, University of North Texas at Dallas, Dallas, TX 75241, USA
*
Author to whom correspondence should be addressed.
Pathogens 2014, 3(2), 390-403; https://doi.org/10.3390/pathogens3020390
Received: 29 December 2013
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Revised: 22 April 2014
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Accepted: 24 April 2014
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Published: 29 April 2014
(This article belongs to the Special Issue Gut Microbiome)
Antibodies of the secretory IgA (SIgA) class comprise the first line of antigen-specific immune defense, preventing access of commensal and pathogenic microorganisms and their secreted products into the body proper. In addition to preventing infection, SIgA shapes the composition of the gut microbiome. SIgA is transported across intestinal epithelial cells into gut secretions by the polymeric immunoglobulin receptor (pIgR). The epithelial surface is protected by a thick network of mucus, which is composed of a dense, sterile inner layer and a loose outer layer that is colonized by commensal bacteria. Immunofluorescence microscopy of mouse and human colon tissues demonstrated that the SIgA co-localizes with gut bacteria in the outer mucus layer. Using mice genetically deficient for pIgR and/or mucin-2 (Muc2, the major glycoprotein of intestinal mucus), we found that Muc2 but not SIgA was necessary for excluding gut bacteria from the inner mucus layer in the colon. Our findings support a model whereby SIgA is anchored in the outer layer of colonic mucus through combined interactions with mucin proteins and gut bacteria, thus providing immune protection against pathogens while maintaining a mutually beneficial relationship with commensals.
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Keywords:
intestinal epithelium; gut bacteria; secretory IgA; polymeric immunoglobulin receptor (pIgR); intestinal mucus; mucin-2
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MDPI and ACS Style
Rogier, E.W.; Frantz, A.L.; Bruno, M.E.C.; Kaetzel, C.S. Secretory IgA is Concentrated in the Outer Layer of Colonic Mucus along with Gut Bacteria. Pathogens 2014, 3, 390-403. https://doi.org/10.3390/pathogens3020390
AMA Style
Rogier EW, Frantz AL, Bruno MEC, Kaetzel CS. Secretory IgA is Concentrated in the Outer Layer of Colonic Mucus along with Gut Bacteria. Pathogens. 2014; 3(2):390-403. https://doi.org/10.3390/pathogens3020390
Chicago/Turabian StyleRogier, Eric W., Aubrey L. Frantz, Maria E.C. Bruno, and Charlotte S. Kaetzel. 2014. "Secretory IgA is Concentrated in the Outer Layer of Colonic Mucus along with Gut Bacteria" Pathogens 3, no. 2: 390-403. https://doi.org/10.3390/pathogens3020390
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