DOP90 Amphiregulin promotes colitis-associated intestinal fibrosis through activation of PI3K/AKT signaling in Intestinal fibroblasts

Abstract Background Intestinal fibrosis is one of the most threatening complications of Crohn’s disease (CD). Amphiregulin (AREG) expression is increased in patients with CD with fibrosis. Methods The role of AREG in activating intestinal fibroblasts and driving fibrogenesis is largely unexplored. In this study, fibrotic and nonfibrotic tissues were obtained from CD patients undergoing surgical resection while normal intestinal tissues were obtained from patients with diverticulum of small intestine. Fibrosis index score for fibrosis were assessed by Masson staining. AREG, collagen Ⅰ and α-SMA expression were determined in intestinal tissues of patients with CD with fibrosis or without fibrosis by qRT-PCR. Wild-type (WT) and Areg knockout (Areg-/-) mice were induced into intestinal fibrosis by dextran sulfate sodium (DSS). We induced intestinal fibrosis in WT mice using a chronic DSS-induced colitis model with or without AREG intraperitoneal injection. The fibrotic indicators in colons were evaluated. Fibroblasts were isolated from fibrotic intestinal surgical resections of patients with CD. The effect of AREG on activation and proliferation in human intestinal fibroblasts was determined. RNA-sequencing of human intestinal fibroblasts treated with or without AREG was performed. Results AREG expression was increased in intestinal fibrotic sites compared with nonfibrotic sites from patients with CD. Mice with Areg deficiency represented with severer intestinal inflammation but alleviated fibrosis in colons. Although additional given AREG attenuated intestinal inflammation in mice with DSS-induced chronic colitis, it promoted more severe intestinal fibrosis. AREG promoted human intestinal fibroblast activation and proliferation by activating PI3K/AKT signaling. PI3K inhibitor suppressed AREG-induced fibroblast activation and proliferation, thus lightened intestinal fibrosis in mice. Besides, AREG promoted secretion of LPA (Lysophosphatidic acid) from intestinal fibroblast, which activated fibroblast through LPAR3/PI3K/AKT pathway. Conclusion These findings reveal that AREG promotes intestinal fibrotic responses in experimental colitis and human patients with CD by promoting fibroblast activation and proliferation through PI3K/AKT pathway. Moreover, LPA secreted from intestinal fibroblast induced by Areg is involved in formation of CD intestinal fibrosis. Thereby, PI3K, AKT, LPA might serve as potential therapeutic targets for fibrosis in CD.