Pure Total Flavonoids From Citrus Protect Against Nonsteroidal Anti-inflammatory Drug-Induced Small Intestine Injury by Promoting Autophagy in vivo and in vitro.

Shanshan Chen,Haijun Cao,Xiaojie Hong,Jianping Jiang,Shuo Zhang,Guanqun Chao

doi:10.3389/fphar.2021.622744

Abstract

Small intestine injury is an adverse effect of non-steroidal anti-inflammatory drugs (NSAIDs) that urgently needs to be addressed for their safe application. Although pure total flavonoids from citrus (PTFC) have been marketed for the treatment of digestive diseases, their effects on small intestine injury and the underlying mechanism of action remain unknown. This study aimed to investigate the potential role of autophagy in the mechanism of NSAID (diclofenac)-induced intestinal injury in vivo and in vitro and to demonstrate the protective effects of PTFC against NSAID-induced small intestine disease. The results of qRT-PCR, western blotting, and immunohistochemistry showed that the expression levels of autophagy-related 5 (Atg5), light chain 3 (LC3)-II, and tight junction (TJ) proteins ZO-1, claudin-1, and occludin were decreased in rats with NSAID-induced small intestine injury and diclofenac-treated IEC-6 cells compared with the control groups. In the PTFC group, Atg5 and LC3-II expression, TJ protein expression, and the LC3-II/LC3-I ratio increased. Furthermore, the mechanism by which PTFC promotes autophagy in vivo and in vitro was evaluated by western blotting. Expression levels of p-PI3K and p-Akt increased in the intestine disease-induced rat model group compared with the control, but decreased in the PTFC group. Autophagy of IEC-6 cells was upregulated after treatment with a PI3K inhibitor, and the upregulation was significantly more after PTFC treatment, suggesting PTFC promoted autophagy through the PI3K/Akt signaling pathway. In conclusion, PTFC protected intestinal barrier integrity by promoting autophagy, which demonstrates its potential as a therapeutic candidate for NSAID-induced small intestine injury.

Highlights

Non-steroidal anti-inflammatory drugs (NSAIDs), such as diclofenac and aspirin, are the most prescribed drugs worldwide and are commonly used in the treatment of chronic pain, tumor chemoprevention, and cardiocerebrovascular diseases (Gwee et al, 2018)
The effects of pure total flavonoids from citrus (PTFC) on autophagy remain unknown. To elucidate this important interaction, we investigated whether improvement in non-steroidal anti-inflammatory drugs (NSAIDs)-induced small intestine injury by PTFC is mediated by its promotion of autophagy
The high-performance liquid chromatography (HPLC) chromate-graphic profile revealed that narirutin, naringin, neohesperidin, and hesperidin were present in the PTFC sample, with retention time peaks of 4.397, 5.229, 5.971, and 7.147 min, respectively

Summary

Introduction

Non-steroidal anti-inflammatory drugs (NSAIDs), such as diclofenac and aspirin, are the most prescribed drugs worldwide and are commonly used in the treatment of chronic pain, tumor chemoprevention, and cardiocerebrovascular diseases (Gwee et al, 2018). Injury to the small intestine induced by NSAIDs is characterized by intestinal mucosal erosion, ulceration, stricture, and even bleeding, which can be severely harmful to the health of the individual (Shin et al, 2017). Dysfunction of the mechanical barrier of the intestinal mucosa is considered to play a vital role in the occurrence and development of NSAID-induced lower digestive tract injury (Bjarnason et al, 2018). Intestinal mucosa permeability increases in NSAID-induced enteropathy, which causes intestinal bacteria, toxins, bile acids, and proteolytic enzymes to penetrate intestinal epithelial cells and cause intestinal mucosal erosion and ulceration, leading to a series of symptoms (Ravikumar et al, 2004). Previous studies have determined that expression of intestinal tight junction (TJ) proteins, including zonula occludens-1 (ZO-1), claudin-1 (CLDN-1), and occludin (OCLN), and cytoskeleton-related proteins decreases in NSAID-induced small intestine injury. Destruction of the intestinal epithelial cytoskeleton and TJs increases intestinal epithelium permeability, which in turn causes intestinal mucosa damage (Chao and Zhang, 2012)

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