Secretory IgA N-glycans contribute to the protection against E. coli O55 infection of germ-free piglets

In this recent Mucosal Immunology paper, the research team around Milan Raska at the Czech Academy of Sciences in Prague and Jiri Mestecky at the University of Alabama at Birmingham investigated the role of IgA-associated glycans for mucosal protection against bacterial infection.  This paper stands out as being one of the few mucosal immunology studies performed in a non-traditional animal model, germ free piglets.  The study showed that removal of glycans from secretory IgA molecules resulted in decreased protection of the immunologically naïve piglets from oral challenge with necrotoxigenic E. coli. Interestingly, the IgA was still able to bind to the E. coli bacteria in the absence of N-linked glycans, pointing to a yet unknown protective mechanism of the glycans found on mucosal IgA antibodies that may involve interactions with mucus or epithelial cells.