Abstract:

Objective

To investigate the potential mechanism of intestinal mucosal barrier injury caused by intestinal epithelial cell autophagy in high-fat-diet fed mice.

Methods

Forty specific pathogenfree mice were randomly divided into normal control group （NCD group）， high fat diet group （HFD group），normal severe acute pancreatitis group （NSAP group）， and high fat diet plus severe acute pancreatitis group（HSAP group），with 10 mice in each group.The normal control group was fed with normal diet，and the highfat diet group was fed with high - fat diet for 8 weeks. Mice in the NSAP and HSAP groups were intraperitoneally injected with 20% L-arginine （L-Arg） （3.5 g/kg， 1 hour interval， 2 times in total） as a stress stimulus， while rats in the NCD and HFD groups were intraperitoneally injected with the same amount of normal saline. ELISA method was used to detect the serum TC， TG， AMY， LPS， IL-6， the content of TNF-α.HE staining was used to observe the pancreas， colon and lung tissue pathological changes.Immunohistochemistry was used to observe the distribution of tight junction proteins Claudin， ZO -1，Occludin， autophagy-related protein LC3 Ⅱ， and pathway-related proteins TLR4 and NF-kB in colon epithelium.Western Blot was used to detect the expression levels of Claudin，ZO-1，Occludin，TLR4，NF-kB and LC3Ⅱin colon.

Results

Compared with NCD group， HFD mice body weight and serum TG， TC level increased obviously.After 20%L-Arg stimulation，compared with NCD group，the levels of serum AMY，TNF-α，LPS and IL-6 in NSAP group were significantly increased （P＜0.05）， and the expression levels of colon Claudin，Occludin and ZO-1 protein were significantly decreased （P＜0.05）.TLR4，NF-κB protein expression significantly increased （P＜0.05）， LC3II protein expression decreased significantly （P＜0.05）. Compared with the NSAP group，the body weight and serum levels of TG，TC，AMY，TNF-α，LPS and IL-6 in the HSAP group were significantly increased （P＜0.05）， and the expression of Claudin， Occludin and ZO-1 in the colon was significantly decreased （P＜0.05）. At the same time， the expression of TLR4 and NF-κB protein in the colon was significantly increased， and the expression of LC3II protein in the colon was significantly decreased （P＜0.05）.

Conclusions

High-fat diet reduces the ability of intestinal mucosal barrier stress in mice， and the mechanism may be related to the regulation of TLR4/NF-κB signaling pathway mediated autophagy.

Key words: High-fat diet, Autophagy, Intestinal epithelial tight junction, Intestinal mucosal barrier, Nuclear factor-kappa B