Butyrate ameliorated-NLRC3 protects the intestinal barrier in a GPR43-dependent manner.

BACKGROUND: Intestinal barrier dysfunctions are related to dysbacteriosis and chronic gut inflammation in type 2 diabetes. Although there is emerging evidence that the chronic gut inflammatory response is stimulated by nucleotide-binding oligomerization domain-like receptors (NLRs), the relationship and precise mechanism between NLRC3 and the colonic epithelial barrier remains largely elusive.

METHODS: We investigated the function and mechanism of NLRC3 in the colonic tissues of diabetic mice and colonic epithelial cell lines. The regulatory mechanism between NLRC3, butyrate and tight junctions was elucidated via a transepithelial electrical resistance measurement, transmission electron microscopy, RNA interference and western blotting.

RESULTS: In this study, we found that NLRC3 expression was decreased in the colonic tissues of diabetic mice. NLRC3 over-expression ameliorated colonic epithelial barrier integrity and up-regulated tight junction proteins in colonic epithelial cells. Knockdown of TRAF6 diminished NLRC3-induced ZO-1/occludin expression. In addition, we demonstrated that butyrate could stimulate NLRC3 expression in both diabetic mice and colonic epithelial cells. GPR43 on colonic epithelial cells is involved in the activation of NLRC3 induced by butyrate.

CONCLUSION: Our findings demonstrated that NLCR3 could ameliorate colonic epithelial barrier integrity in diabetes mellitus in a TRAF6-dependent manner, and NLCR3 was stimulated by butyrate via binding GPR43 on colonic epithelial cells.