An elevated deoxycholic acid level induced by high-fat feeding damages intestinal stem cells by reducing the ileal IL-22.

Long-term high-fat diet (HFD) destroys the intestinal mucosal barrier by damaging intestinal stem cells (ISCs). A HFD can increase the concentration of intestinal deoxycholic acid (DCA) and decrease the secretion of interleukin-22 (IL-22), which plays an important role in the proliferation, repair and regeneration of ISCs. We hypothesized that increased level of intestinal DCA induced by a HFD leads to ISC dysfunction by reducing the IL-22 levels in intestinal tissues. In this study, 2 weeks of a DCA diet or a HFD damaged ileal ISC and its proliferation and differentiation, resulting in a decrease in Paneth cells and goblet cells. Importantly, 2 weeks of a DCA diet or a HFD also reduced ileal IL-22 concentration, accompanied by a decreased number of group 3 innate lymphoid cells in ileal mucosa, which produce IL-22 after intestinal injury. Concurrent feeding with bile acid binder cholestyramine prevented all these changes induced by a HFD. In addition, in vitro study further confirmed that exogenous IL-22 reversed the decline in the proliferation and differentiation of ileal ISCs induced by DCA stimulation. Collectively, these results revealed that the decrease in intestinal IL-22 induced by DCA may be a novel mechanism by which HFD damages ISCs. The administration of IL-22 or a bile acid binder may provide novel therapeutic targets for the metabolic syndrome caused by a HFD.