Intestinal homeostasis governed by mesenchymal stromal cells

Abstract

Abstract The mammalian intestine harbors numerous bacteria and contains a large number of immune cells. A continuous dialogue between immune cells and luminal microbes is critical for the maintenance of the intestinal homeostasis. The intestinal epithelium is a single-layered cell sheet that separates numerous microbes and the immune system. The appropriate development and maintenance of the epithelium are essential for the clearance of pathogens and the prevention of excess immune responses against commensal microbes. Microfold (M) cells are epithelial cells specialized for bacterial sampling and initiate germinal center formation and IgA production in the gut associated lymphoid tissues (GALTs). Here, we show that previously unrecognized mesenchymal stromal cells regulate an epithelial function and induce IgA production in the GALTs. The impairment of these mesenchymal stromal cells caused a reduction in IgA production against commensal bacteria, resulting in the altered composition of the gut microbiota. These results suggest that these mesenchymal stromal cells contribute to the maintenance of the intestinal homeostasis.