Xue-Jie-San prevents the early development of colitis-associated intestinal fibrosis by blocking Notch1 and FGL1 signaling pathways

Intestinal fibrosis is a debilitating complication of CD. Currently, there is no effective medication available for preventing or reversing CD-related intestinal fibrosis. This study aimed to assess the efficacy and underlying mechanisms of XJS in the treatment of colitis-associated intestinal fibrosis. Materials and

Our findings validated that XJS prevented the early development of CD-related intestinal fibrosis by blocking the Notch1 and FGL1 signaling pathways to activate autophagy and thereby inhibit EMT and EndoMT.

A rat model of CD-related intestinal fibrosis was induced by 2,4,6-trinitrobenzene sulfonic acid administration and treated with XJS. The pathological changes of intestinal fibrosis were evaluated using Masson staining. Collagen deposition and epithelial-to-mesenchymal transition (EMT) were verified by immunohistochemical staining and Western blot analysis. Endothelial-to-mesenchymal transition (EndoMT) was assessed with immunofluorescence and immunohistochemical staining as well as Western blot analysis. Transmission electron microscopy was utilized to observe autophagosomes. The levels of autophagy-related proteins were detected via immunofluorescence staining and Western blot. Finally, the mTOR/ULK1 signaling pathway regulated by Notch1 or FGL1 was analyzed by Western blot.

The results found that XJS ameliorated intestinal fibrosis through reducing the deposition of collagens such as Collagen 1 and Collagen 3. XJS inhibited the EMT process by increasing E-cadherin levels and decreasing the expressions of N-cadherin, Vimentin and Snail, which played a crucial role in collagen secretion and intestinal fibrosis. In addition, XJS also repressed the EndoMT process as reflected by the upregulation of CD31 and VE-cadherin levels and the downregulation of FSP1 and α-SMA expressions. Autophagy was activated following XJS treatment via suppression of the mTOR/ULK1 signaling pathway. Furthermore, XJS acted as an inhibitor of Notch1 and FGL1 signals, both of which regulated the mTOR signaling. Conclusions: Our findings validated that XJS prevented the early development of CD-related intestinal fibrosis by blocking the Notch1 and FGL1 signaling pathways to activate autophagy and thereby inhibit EMT and EndoMT.