Background
Accumulating evidence suggests that dysbiosis plays a role in the pathogenesis of intestinal diseases including inflammatory bowel disease (IBD) as well as extra-intestinal disorders. Immunoglobulin A (IgA) is the main antibody isotype secreted into the intestinal lumen. IgA plays a critical role in the defense against pathogens and in the maintenance of intestinal homeostasis. However, how secreted IgA regulates gut microbiota is not completely understood.
Methods & Results
In this study, we isolated monoclonal IgA antibodies from small intestine of healthy mouse. As a candidate of efficient gut microbiota modulator, we selected a W27 IgA that binds to multiple bacteria but not beneficial ones such as Lactobacillus casei. Via specific recognition of an epitope in serine hydroxymethyltransferase (SHMT), a bacterial metabolic enzyme, W27 could bind to and suppress the cell growth of Escherichia coli but not Lactobacillus casei in vitro, indicating an ability to improve the intestinal environment. By modulating the gut microbiota in vivo, W27 oral treatment could have therapeutic effect on both lymphoproliferative disease and colitis models in mice.
Conclusion
W27 IgA oral treatment is a potential remedy for inflammatory bowel disease, acting through restoration of the host-microbial symbiosis.