[Therapeutic effects of Baitouweng Decoction on ulcerative colitis mice with dampness-heat syndrome via inhibiting CaSR-Gq/11-MAPK signaling pathway based on fecal microbiota transplantation].

This study aimed to investigate whether Baitouweng Decoction(BTD) exerts pharmacodynamic effects on ulcerative colitis(UC) mice with dampness-heat syndrome in the large intestine by modulating the gut microbiota and its metabolites to inhibit the calcium sensing receptor(CaSR)-G-protein alpha subunit Q/G-protein alpha subunit 11(Gq/11)-mitogen activated protein kinase(MAPK) signaling pathway. In the experiment, mice were divided into the following groups: a normal group, a model group, a Baitouweng Decoction fecal microbiota transplantation(BTD-FMT) group, a normal-FMT group, and a normal-FMT + Akkermansia muciniphila group. Except for the normal group, a UC with dampness-heat syndrome model was established in all mice. The corresponding fecal supernatant or Akkermansia muciniphila was administered on days 9, 11, 13, 15, 17, 19, and 21. Items below were recorded: body weight, diet, dampness-heat syndrome modeling conditions, and disease activity index(DAI) scores. The distribution and fluorescence intensity of fluorescein isothiocyanate(FITC)-Dextran in the gut were detected using a small animal 3D live imaging system. Pathological changes in the colon and tongue tissues were observed using hematoxylin-eosin(HE) staining. The mRNA expression of inflammatory factors and Muc2 in colon tissue was measured by quantitative real-time PCR(qRT-PCR). The expression levels of forkhead box protein p3(Foxp3) and retinoic acid related orphan receptor γt(RORγt) in colon tissue were analyzed by immunohistochemistry. Goblet cell and mucin expression were analyzed by alcian blue-periodic acid-Schiff(AB-PAS) staining. Western blot was employed to detect the expression of Zonula occludens-1(ZO-1), Occludin, Claudin-1, CaSR, G-protein alpha subunit αQ(Gnaq), G-protein alpha subunit 11(Gna11), extracellular signal-regulated kinase 1/2(ERK1/2), c-Jun N-terminal kinase(JNK), mitogen-activated protein kinase p38(p38 MAPK, p38), phosphorylated extracellular signal-regulated kinase 1/2(p-ERK1/2), phosphorylated c-Jun N-terminal kinase(p-JNK), and phosphorylated mitogen-activated protein kinase p38(p-p38 MAPK, p-p38) in colon tissue. The results indicated that compared with the normal group, model mice with dampness-heat syndrome showed significant increases in rectal temperature, water intake, DAI scores, total movement trajectories/distance traveled in the open field test, and dampness-heat syndrome scores. Compared with the model group, BTD-FMT exerted therapeutic effects on UC mice with dampness-heat syndrome, which were evidenced by significantly ameliorated dampness-heat symptoms and tongue tissue pathology, reduced DAI scores, restored colon length, decreased colon histopathological scores, and modulated immune responses. Furthermore, BTD-FMT downregulated the mRNA expression of tumor necrosis factor-α(TNF-α), interleukin-1β(IL-1β), and interleukin-6(IL-6) while upregulating interleukin-10(IL-10) and interleukin-4(IL-4) expression. Barrier protein levels were appropriately upregulated, alleviating increased intestinal barrier permeability. Additionally, the expression balance between Foxp3 and RORγt was restored, the goblet cell repair and mucin expression were promoted, and the expression of key proteins in the CaSR-Gq/11-MAPK signaling pathway was suppressed in colon tissue. In terms of therapeutic effect, BTD-FMT was superior to normal-FMT. Supplementation with Akkermansia muciniphila partially mimicked the therapeutic effects of BTD-FMT and achieved a synergistic effect when combined with normal-FMT. In conclusion, BTD exerts anti-inflammatory and intestinal mucosal barrier repair effects in UC mice with dampness-heat syndrome via gut microbiota and metabolite modulation, and the CaSR-Gq/11-MAPK signaling pathway inhibition. Akkermansia muciniphila enhances the effect of normal-FMT.