The intestinal immune system is emerging as an important contributor to
obesity-related
insulin resistance, but the role of intestinal B cells in this context is unclear. Here, we show that high fat diet (HFD) feeding alters intestinal IgA+ immune cells and that
IgA is a critical immune regulator of
glucose homeostasis. Obese mice have fewer IgA+ immune cells and less
secretory IgA and
IgA-promoting immune mediators. HFD-fed
IgA-deficient mice have dysfunctional
glucose metabolism, a phenotype that can be recapitulated by adoptive transfer of intestinal-associated pan-B cells. Mechanistically,
IgA is a crucial link that controls intestinal and adipose tissue
inflammation, intestinal permeability, microbial encroachment and the composition of the intestinal microbiome during HFD. Current
glucose-lowering
therapies, including
metformin, affect intestinal-related IgA+ B cell populations in mice, while
bariatric surgery regimen alters the level of fecal
secretory IgA in humans. These findings identify intestinal IgA+ immune cells as mucosal mediators of whole-body
glucose regulation in diet-induced
metabolic disease.