Aqueous extract of Paeoniae Radix Alba alleviates DSS-induced ulcerative colitis via inhibition of the IFN-γ/JAK1/STAT1 signaling pathway and restoration of intestinal barrier function

BACKGROUND: Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by aberrant immune activation and intestinal microenvironment dysregulation. Paeoniae Radix Alba (RPA), a classic traditional Chinese medicine (TCM) derived from the roots of Paeonia lactiflora, possesses potent anti-inflammatory, immunomodulatory, and analgesic properties. It has been extensively employed in traditional Chinese prescriptions for the treatment of UC. However, the precise mechanism underlying its beneficial effects in alleviating UC pathology remains to be clearly elucidated. PURPOSE: We explored the regulatory effects of the aqueous extract of RPA (hereafter termed RPAE) on the Janus kinase 1 (JAK1)/signal transducer and activator of transcription 1 (STAT1) signaling pathway and intestinal barrier integrity, to clarify the potential mechanisms by which RPAE alleviates UC progression. METHODS: The constituents of RPAE were identified by UPLC-Q-Orbitrap-MS. Its therapeutic efficacy was evaluated in a dextran sodium sulfate (DSS)-induced UC mouse model by the following parameters: disease activity index (DAI), colon length, colonic histopathology, and inflammatory cytokine levels [Enzyme-linked immunosorbent assay (ELISA) and qRT-PCR] in serum and colonic tissues. Hematoxylin and eosin (H&E) staining and transmission electron microscopy (TEM) were used to visualize colonic damage. Fluorescein isothiocyanate (FITC)-dextran assay assessed intestinal barrier integrity. Furthermore, transcriptomics analysis was conducted to explore the potential molecular mechanism, and the key pathways were verified in a lipopolysaccharide (LPS)-induced inflammatory model established in RAW 264.7 macrophages. RESULTS: A total of 51 components were identified in RPAE, among which monoterpene glycosides were predominant. In vivo experiments demonstrated that RPAE ameliorated the UC-associated symptoms in mice, including body weight loss, colon shortening, and elevated DAI scores. Moreover, RPAE regulated the secretion of TNF-α, IL-1β, IFN-γ, and IL-10 in the serum and colon tissues of UC mice. Histopathological examination further confirmed that RPAE treatment ameliorated colon tissue damage and markedly upregulated the expression of ZO-1 and Occludin, thereby preserving intestinal barrier integrity. Transcriptomic bioinformatic analysis revealed significant enrichment of differentially expressed genes in the JAK-STAT signaling pathway. Western blotting (WB) results revealed that RPAE downregulated the protein levels of IFN-γ, p-JAK1, p-STAT1, and NF-κB in both DSS-induced UC mice and inflammation cellular model. CONCLUSIONS: RPAE alleviates DSS-induced colitis in association with suppression of the IFN-γ/JAK1/STAT1 signaling pathway. This discovery provides a potential therapeutic target for UC.