Circulating Antibodies Specific for Dietary Fiber Glycans

Abstract

Abstract The mammalian gut lumen contains an extremely diverse collection of microbial species and dietary constituents. Protein and carbohydrate antigens on commensal bacterial surfaces stimulate the production of specific antibodies, which can be secreted and bind their epitopes in the lumen. Despite the high abundance of plant polysaccharides (dietary fiber) in the intestine, it remains unclear whether these foreign carbohydrates stimulate the production of secreted anti-fiber antibodies. Here, we characterize antibody specificity in mice using a panel of artificial food particles composed of microscopic magnetic beads, each simultaneously tagged with a fluorescent barcode and coated with one of 64 different dietary or host glycan preparations. Using this approach, we detected secreted antibodies in the cecum and circulating antibodies in serum that selectively bind subsets of dietary glycans. Alteration of the host diet to include supplemental dietary fiber led to a significant increase in anti-fiber antibodies in serum. In contrast, cecal fiber-specific antibody reactivity was not increased after fiber feeding. Analysis of the gut microbiota revealed that relative abundances of Akkermansia muciniphila were significantly higher in mice fed supplemental fiber relative to mice fed a control diet. This work raises the possibility that taxa such as A. muciniphila are involved in the production of antibodies specific for dietary components. Supported by a grant from NIH (K01 DK124445)