Involvement of the TLR4/NF-κB signaling pathway in the repair of esophageal mucosa injury in rats with gastroesophageal reflux disease

Abstract

Background/Aims: Numerous studies have highlighted the activation of NF-κB in the esophageal mucosa during the early stages of gastroesophageal reflux disease (GERD). The present study aimed to investigate the role of the TLR4/NF-κB signaling pathway in GERD rat models. Methods: Wistar rats (n = 60) were recruited to establish a GERD animal model. Distal esophageal pH was assessed, followed by determination of the contents of thiobarbituric acid-reactive species (TBARS) and reactive oxygen species (ROS) in esophageal mucosa homogenate. ELISA was employed to detect the levels of inflammatory factors (IL-6, IL-8, IL-10 and TNF-α) in esophageal mucosa. The expression of MMP-3, MPP-9, Cldn1 and Cldn4 was determined by immunohistochemistry. RT-qPCR and western blot analysis were applied to evaluate the protein expressions in TLR4/NF-κB signaling pathway, while TUNEL staining was utilized to examine the apoptosis rate in the esophageal mucosal tissues. Results: Distal esophageal pH of the rats was higher in the GERD + PDTC group than in other groups. Levels of inflammatory factors in esophageal mucosal tissues were downregulated with the inhibition of NF-κB, which was determined to be associated with the decreased contents of TBARS and ROS. Moreover, decreased MMP-3 and MPP-9 in addition to elevated Cldn1 and Cldn4 were detected in the esophageal mucosa as a result of the inactivation of NF-κB. The TLR4/NF-κB signaling pathway-related proteins (TLR4, NF-κB and IκBα); the rate of apoptosis was demonstrated to be suppressed in the GERD + PDTC group, while inactivating NF-κB was found to alleviate the tissue damage observed in the esophageal mucosa. Conclusion: The key findings of the current study demonstrate that the inactivation of the TLR4/NF-κB signaling pathway alleviates oxidative stress injury and promotes the repair of esophageal mucosal injury among rats with GERD, highlighting a potential novel GERD mechanism.