No abstract

a high-fat diet (HFd) or obesity-promoting diet is closely associated with metabolic diseases and intestinal tumors, particularly in middle-aged individuals (typically 45-64 years old). The intestinal epithelium constitutes a barrier that separates the host from the food and microbiota in the gut, and thus, a dysfunctional epithelium is associated with a number of diseases. However, the changes caused to the function of intestinal epithelium in response to an HFd have not been well-studied to date. in the present study, middle-aged female mice (12 months old) fed an HFd for a period of 14 weeks were used to determine the effects of HFd on the intestine. characteristics including the body weight, fat deposition, glucose metabolism, inflammatory state and intestinal morphology were assessed, while the intestinal stem cell (iSc) counts and the ability of isolated intestinal crypts to form organoid bodies in 3d culture were examined. intestinal epithelial barrier function, including secretory defense, tight junctions and cell apoptosis, were also studied. Morphologically, the HFd resulted in a mild reduction in the length of villi of the small intestine, the colon length and the depth of colon crypts. in addition, the iSc counts were increased in the small intestine and colon in HFd-fed mice. The ability of crypts to grow into organoids (mini-guts) was also increased in crypts obtained from mice fed an HFd, while HFd compromised the epithelial barrier function of the colon. These results demonstrated how an HFd affects the intestinal epithelium and highlighted the need to carefully consider dietary patterns.

Clinical evidence shows that visceral fat accumulation decreases whereas sc fat increases in patients treated with thiazolidinediones (TZDs), a type of peroxisome proliferator-activated receptor (PPAR)γ agonist. To clarify the molecular mechanism of the differential effects of PPARγ agonists on sc and visceral adipose, we investigated expression profiling of PPARγ-regulated micro-RNAs (miRNAs) using miRNA microarray. The level of 182 miRNAs changed in human sc adipose treated with pioglitazone, whereas only 46 miRNAs changed in visceral adipose. Among these miRNAs, 27 miRNAs changed in both human sc and visceral adipocytes. Specifically, 7 miRNAs changed at the same direction in sc and visceral adipocytes, whereas 20 miRNAs changed at opposite directions in these two fat depots. Bioinformatics analysis showed that these miRNAs and the predicted target genes were involved in TGF-β-, Wnt/β-catenin-, and insulin-signaling pathways and related to metabolic regulation or cell cycle. Among the miRNAs changed at the same direction in sc and visceral adipocytes, miR-378, located in the first intron of PPARγ coactivator 1β (PGC1β), was coordinately expressed with PGC1β during adipogenesis. Moreover, miR-378 and PGC1β were both up-regulated by PPARγ agonist. We also provided evidence that miR-378 promoted adipogenesis in sc fat, but not in visceral fat. These results display miRNAs expression profiling altered in sc and visceral adipogenesis regulated by PPARγ and suggest a potential mechanism underlying the differential effects of TZDs on the 2 fat depot accumulations.