Phellodendrine ameliorates intestinal inflammation and protects mucosal barrier via modulating COL1A1, VCAM1 and IL-17 a

Background: Phellodendrine (PHE) has anti-inflammatory and antioxidant effects. However, the function of PHE in treating inflammatory bowel disease (IBD) has not been fully elucidated. The aim of this study was to investigate the effects and mechanisms of PHE on IBD with in vivo and in vitro assays.

Materials and methods: Bioinformatics was used to identify hub genes associated with IBD pathogenesis. Virtual screening was applied to predicting the natrual compounds targeting hub genes. A mouse model with colitis was established by oral administration of 3 % dextran sulfate (DSS), and the mice were treated with normal saline or PHE (30 mg/kg/day or 80 mg/kg/day). On day 14, the mice were sacrificed and their colons were collected for measurement and histological analysis. The pathological change and inflammation of the tissues in different groups also were evaluated. In addition, the intestinal epithelial Caco-2 cell line was treated with lipopolysaccharide (LPS) to establish an in vitro intestinal inflammation model. CCK-8 assay and flow cytometry were used to detect the effects of PHE (10 μM or 40 μM) on cell viability and Apoptosis. Western blot was used to the investigate the regulatory effects of PHE on the expression levels of zonula occludens 1 (ZO-1), occludin, claudin-1, collagen type I alpha 1 (COL1A1), vascular cell adhesion molecule 1 (VCAM1), interleukin-17 A (IL-17 A), phosphorylated AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR).

Results: COL1A1 and VCAM1 were identified as therapeutic targets in IBD. PHE was identified as a natural drug simultaneously targeting COL1A1 and VCAM1. PHE treatment alleviates the weight loss and symptoms of mice induced by acute colitis. PHE treatment reduced myeloperoxidase (MPO) activity and pro-inflammatory cytokine levels in colonic tissues, and inhibited expression levels of COL1A1, VCAM1 and IL-17 A, and promoted expression levels of ZO-1, occludin and claudin-1. In vitro, PHE treatment also protected Caco-2 cells from LPS-induced inflammation, which was dependent on AMPK/mTOR pathway.

Conclusion: PHE ameliorates intestinal inflammation and intestinal barrier injury, probably via modulating COL1A1, VCAM1 and IL-17 A, and acting on AMPK/mTOR pathway. PHE may be a potential natural drug for IBD treatment.

IL-17 signaling pathway; Inflammation; Inflammatory bowel disease; Intestinal mucosal barrier; Phellodendrine.