Oleanolic acid improves intestinal inflammation and fibrosis in Crohn's disease via regulation the target of PPAR-γ based on network pharmacology analysis combined with experimental validation

Background As a form of chronic inflammatory bowel disease, crohn's disease (CD) is a condition in which intestinal fibrosis is a defining characteristic. Oleanolic acid (OA), as a naturally occurring pentacyclic triterpenoid compound, has gradually been applied in the research of disease treatment. We systematically analyzed the targets of OA regulating CD, as well as its potential role and mechanism. Methods The potential target sites of OA were identified using network pharmacology analysis integrated with multiple public databases, network construction, function and pathway enrichment analyses, and molecular docking simulations. Cellular thermal shift assay was employed to confirm the interaction between OA to the candidate target. Cell and animal experiments verified the regulatory mechanism of OA in treating CD. Results A collection of 338 genes linked to OA and 4542 CD-related genes were retrieved. Then, we obtained 142 therapeutic targets of OA against CD. Of these, 5 genes were considered as core targets by network construction. Function and pathway enrichment analyses revealed that OA alleviated CD through regulation of inflammatory response and PPAR signaling pathway. The molecular docking indicated that PPAR-γ had a strong binding energy with OA. The molecular dynamics simulation and cellular thermal shift assay results showed that OA directly binds to PPAR-γ. Our experiments demonstrated that OA could reduce intestinal inflammation and fibrosis in CD, accompanied by increased PPAR-γ expression. OA decreased pro-inflammatory cytokines and TGF-β1 levels while increasing IL-10 levels, accompanied by increased MMP-1 and MMP-3 expression and decreased Col1a1, Col3a1, TIMP-1, Fibronectin, and α-SMA expression, culminating in the amelioration of colonic pathological tissues. Conclusion These findings revealed that OA exerts therapeutic effects against intestinal inflammation and fibrotic remodeling in CD through a PPAR-γ-mediated mechanism, providing new insights for the development of drugs to improve intestinal inflammation and fibrosis in CD.