Exploring the Mechanism of Xianglian Pills in Treating Ulcerative Colitis Based on Metabolomics

Based on the study of serum metabolomics, the mechanism of Xianglian Pill (XLP) in improving ulcerative colitis (UC) mice induced by dextran sulfate sodium (DSS) was investigated. The main active components of XLP were detected by HPLC method. The disease activity index was evaluated by daily recording of the body weight, fecal characteristics, and occult blood status; the mRNA expression levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-1β were detected by qPCR; the activity of myeloperoxidase (MPO) was detected using a myeloperoxidase kit; the pathological changes of the colon tissue were observed by HE staining; the expression levels of intestinal mucosal tight junction proteins ZO-1 and Occludin were detected by immunohistochemistry. Non-targeted metabolomics analysis was conducted on the metabolite levels in the serum samples of UC mice, and the differential metabolites were screened out by principal component analysis and orthogonal partial least squares discriminant analysis. The metabolic pathways related to the differential metabolites were determined using MetaboAnalyst 5.0. Finally, the expression of key proteins in the main metabolic pathways was detected by Western blotting. The results showed that XLP could significantly improve the weight loss, the colon shortening, the disease activity index and the damage of colon tissues in UC mice, reduce the levels of pro-inflammatory factors (IL-6, IL-1β, TNF-α), MPO activity and the expression levels of ZO-1 and Occludin. Metabolomics analysis revealed that a total of 38 potential differential metabolites were associated with XLP intervention in UC mice, mainly involving sphingolipid metabolism, glycerophospholipid metabolism, and linoleic acid metabolism. Sphingolipid metabolism was closely related to the PI3K-AKT signaling pathway. Western blot results showed that XLP could significantly down-regulate the protein expression of sphingosine kinase 1 (SphK1) and phosphoglycerate dehydrogenase (PHGDH), thereby alleviating the activation of the PI3K-AKT pathway. In conclusion, XLP could significantly improve the disease state of DSS-induced UC mice, and its mechanism may be closely related to the regulation of sphingolipid metabolism-PI3K-AKT pathway. This study provides a theoretical basis for clarifying the scientific connotation of XLP in the treatment of UC.