Intestinal epithelial chemokine (C-C motif) ligand 7 overexpression protects against high fat diet-induced obesity and hepatic steatosis in mice

BACKGROUND: We previously found that the intestinal epithelial chemokine (C-C motif) ligand 7 (CCL7) plays an important role in the development of toxin-induced acute liver damage. The detailed effects of intestinal epithelial CCL7 on chronic diseases; however, are still unclear. Here, we aimed to investigate the impact of intestinal epithelial CCL7 overexpression on high-fat diet (HFD)-induced obesity and steatohepatitis in mice. METHODS: Intestinal epithelial CCL7 overexpression (CCL7(tgIEC)) mice and their wild-type (WT) littermates were fed with normal chow or HFD for 16 weeks to induce obesity and non-alcoholic fatty liver disease. Body weight gain, as well as adipose tissue index were assessed. Liver injury was monitored by histological analysis and real time polymerase chain reaction. Gut microbial composition was analyzed by 16S rRNA gene sequencing. RESULTS: We found that the CCL7(tgIEC) mice on a HFD had markedly decreased weight gain (8.9 vs. 17.0 g, P < 0.05) and a lower adipose tissue index that include mesenteric fat (1.0% vs. 1.76%, P < 0.05), gonadal fat (2.1% vs. 6.1%, P < 0.05), subcutaneous fat (1.0% vs. 2.8%, P < 0.05) compared to WT animals. HFD-induced glucose intolerance and insulin resistance were also significantly improved in CCL7(tgIEC) mice compared to WT. Furthermore, HFD-fed CCL7(tgIEC) mice displayed less hepatic lipid accumulation and lower expression of inflammatory factors than WT mice. 16S rRNA gene sequencing demonstrated that CCL7 overexpression in intestinal epithelial cells improved HFD-induced gut microbial dysbiosis. CONCLUSIONS: Our study revealed that CCL7 overexpression in the intestinal epithelium protects mice against the progression of diet-induced obesity, hepatic steatosis, and enteric dysbiosis.