IgA regulates the composition and metabolic function of gut microbiota by promoting symbiosis between bacteria

Abstract

IgA regulates the composition and function of gut microbiota. Nakajima et al. show that a heavily glycosylated monoclonal IgA coats B. theta and induces Mucus-Associated Functional Factor in vivo to enhance symbiotic interactions with commensal bacteria to maintain gut homeostasis.

Metabolism at the centre of the host–microbe relationship

“…Aiming to test whether glycan-glycan interactions between IgA, bacteria and mucous are important for modulating gut microbiota, Nakajima et al [91] developed a highly glycosylated antiovalbumin IgA monoclonal antibody. Binding of this highly glycosylated, antigen-independent antibody altered microbial expression of polysaccharide utilization loci (PUL) genes, particularly in mucosal-associated bacteria, and not bacteria present in the colonic content [91]. Binding of this highly glycosylated, antigen-independent antibody altered microbial expression of polysaccharide utilization loci (PUL) genes, particularly in mucosal-associated bacteria, and not bacteria present in the colonic content [91].…”

“…This antibody bound preferentially to metabolically active members of the Bacteriodales via glycan-lipopolysaccharide (LPS) interactions. Highly expressed PUL genes included components of the starch utilization system, which the authors propose act as symbiotic factors enabling bacterial presence in the mucous environment, and have provisionally named them as mucous-associated functional factors (MAFFs) [91]. Highly expressed PUL genes included components of the starch utilization system, which the authors propose act as symbiotic factors enabling bacterial presence in the mucous environment, and have provisionally named them as mucous-associated functional factors (MAFFs) [91].…”

“…They found that IgA promoted the clearance of metabolites from the host tissues by accelerating microbial clearance [92]. For example, several studies show that IgA can increase the dwell time of certain bacteria, which can have follow-on effects on the wider microbial composition and metabolite availability [90,91]. For example, several studies show that IgA can increase the dwell time of certain bacteria, which can have follow-on effects on the wider microbial composition and metabolite availability [90,91].…”

“…A recent study showed further importance of IgA coating of a strain of Bacteroidetes, which was important for modulating interphylum bacterial interactions and cooperation via shared metabolism [91]. Aiming to test whether glycan-glycan interactions between IgA, bacteria and mucous are important for modulating gut microbiota, Nakajima et al [91] developed a highly glycosylated antiovalbumin IgA monoclonal antibody. This antibody bound preferentially to metabolically active members of the Bacteriodales via glycan-lipopolysaccharide (LPS) interactions.…”

Growing, evolving and sticking in a flowing environment: understanding IgA interactions with bacteria in the gut

“…Indeed many Bacteroides strains carry the complete machinery required to degrade mammalian N‐glycans and may reasonably use these as a carbon source in the gut lumen, similar to the accepted role of mucins as a bacterial carbon source. Non‐cognate binding of sIgA to B. thetaiotaomicron mediated an effect on the expression of polysaccharide utilization loci and facilitated symbiosis with other phyla such Firmicutes . A simple nutritional explanation for pro‐colonization effects has therefore not yet been excluded.…”