Xianglian Pill Attenuates Ulcerative Colitis Through TLR4/MyD88/NF-κB Signaling Pathway

Ethnopharmacological relevance: Xianglian Pill (XLP) is a classical Chinese medicine prescription applied for controlling ulcerative colitis(UC). Whereas, the underlying mechanism remains unclear.Aim of the study: The present work was aimed to investigate the mechanism of XLP in dextran sulfate sodium(DSS)-induced UC via the TLR4/MyD88/NF-κB signaling signaling in mice.Materials and methods: The major components of XLP were detected by HPLC-DAD. The ulcerative colitis model was induced by DSS in mice. 5-Amino Salicylic Acid (5-ASA) group and XLP were intragastrically treated. Disease activity index (DAI) and colon length were monitored and HE staining was conducted. GSDMD-N and TLR4 expressions in colon tissues were visualized by immunofluorescence. TLR4 mRNA was measured by RT-qPCR. The expressions of NLRP3, active-caspase-1, GSDMD-N, TLR4, MYD88, NF-κB, p-NF-κB, and the ubiquitination of TLR4 on colon tissues were detected by Western blot. Myeloperoxidase (MPO) enzyme activity was examined and serum inflammatory factors IL-1β, IL-6, TNF-α, and IL-18 were determined by ELISA. TLR4 -/- mice were applied for verifying the mechanism of XLP-attenuated DSS symptoms.Results: The XLP treatment extended colon length, reduced DAI, and attenuated histopathological alteration in DSS-induced mice. XLP administration suppressed MPO activity and reduced the content of IL-1β, IL-6, TNF-α and IL-18 in serum. XLP also inhibited the expression levels of GSDMD-N, TLR4, NLRP3, active-caspase-1, MyD88, p-NF-κB/NF-κB in colon tissues of DSS-induced mice. TLR4 -/- mice proved that TLR4 was involved in XLP-mediated beneficial effect on DSS-induced ulcerative colitis.Conclusions: XLP might treat ulcerative colitis by regulating the TLR4/MyD88/NF-κB signaling pathway.