Mechanism by Which Tong Xie Yao Fang Heals the Intestinal Mucosa of Rats with Ulcerative Colitis through the Hippo Pathway

OBJECTIVE: Tong Xie Yao Fang (TXYF) is a classic and effective prescription in traditional Chinese medicine which is used to treat ulcerative colitis (UC). Our study investigated the effect of TXYF on Hippo pathway activation in UC-induced intestinal mucosa injury and explored the possible mechanism. METHOD: After ulcerative colitis was successfully induced by trinitrobenzene sulfonic acid (TNBS), 48 Sprague Dawley (SD) rats were randomly divided into a control group, model group, TXYF group, and sulfasalazine group and treated with the corresponding drugs for 28 days. The parameters including body weight, colon length, spleen index, and disease activity index (DAI) and histopathological characteristics were assessed. The myeloperoxidase (MPO) activity and IL-6 level in the colon mucosa were determined with the corresponding commercial kits. The expressions of the Hippo pathway components YAP1, TAZ, P-YAP, and LATS1 were detected in the colon mucosa of each group on different stages by quantitative real-time PCR (qRT-PCR) and western blotting. Immunohistochemical staining was used to evaluate the growth and apoptosis of the colon epithelium. RESULT: TXYF significantly improved the weight loss, colonic shortening, DAI, spleen enlargement, and histopathological score of the rats with TNBS-induced UC. TXYF also reduced the MPO activity and expression of IL-6 in the colon mucosa. Furthermore, treatment with TXYF significantly increased YAP1 expression in the early stage (3–7 days) and significantly decreased YAP1 expression in the late stage (14–28 days). In the early stage, TXYF inhibited Hippo pathway activity, which promoted proliferation and regeneration of the intestinal mucosa. In the late stage, the Hippo pathway was activated, thereby inhibiting apoptosis and promoting intestinal mucosal differentiation. CONCLUSION: TXYF alleviated the inflammatory response and promoted mucosal healing in rats with UC, which was probably achieved through the Hippo pathway. These results indicated that TXYF was a potential therapy for treating UC.