Dihydromyricetin regulates intestinal epithelial barrier function of type 2 diabetes mellitus mice through SIRT3

Abstract

Objective To investigate the effect of dihydromyricetin (DHM) on high-fat diet (HFD)-induced intestinal epithelial barrier function in mouse model of type 2 diabetes mellitus (T2DM), and to reveal the mechanism involved with SIRT3 in mediating DHM in the process. Methods Eighteen 7-week-old SPF male wild-type (WT) mice and 30 SIRT3 KO mice were randomly divided into the control group (NC), HFD group and HFD+DHM group, respectively. The intervention time was 12 weeks. The body weight and food intake of the animals were monitored regularly. At week 12 of intervention, intestinal permeability were tested. After the mice were sacrificed, serum biochemical indexes and LPS levels as well as the intestinal histopathology were detected and observed. The expression of tight junction proteins (ZO-1, Occludin) and inflammatory factors (TNF-α, IL-1β and IL-6) in the isolated small intestinal epithelial cells and Caco-2 cells were detected by qRT-PCR and Western blotting. Then the Caco-2 cells were further infected with lentivirus (LV-SIRT3) to knock down the SIRT3 expression, and the expression levels of above molecules were detected after DHM and LPS treatment. Results In the WT and SIRT3 KO mice, HFD induced a significant increased body weight, abnormal glucose level and lipid metabolism, increased intestinal permeability and obvious changes in intestinal epithelial structure (reduced small intestinal epithelium crypt depth and villi length), as well as decreased levels of tight junction proteins and elevated levels of inflammatory factors. Furthermore, the alterations induced by HFD in SIRT3 KO mice were more significant than those in WT mice (P0.05). In the LV-SIRT3-infected Caco-2 cells, DHM failed to inhibit LPS-induced enhanced expression of the inflammatory cytokines and decreased expression of the tight junction proteins (P>0.05). Conclusion SIRT3 plays an important role in DHM-induced increased expression of small intestinal epithelial tight junction proteins, reduced expression of the inflammatory factors, maintenance of the intestinal epithelial barrier integrity and permeability and improvement of glycolipid metabolism, and thus is beneficial to delay the development of T2DM.

Keywords

• dihydromyricetin
• type 2 diabetes mellitus
• intestinal epithelial barrier
• sirt3
• tight junction protein