Study on the mechanism of Huangqin Decoction on rats with ulcerative colitis of damp-heat type base on mtDNA, TLR4, p-PI3K, p-Akt protein expression and microbiota

Huangqin decoction (HQD), composed of Scutellaria(Huangqin), Peony(Shaoyao), Liquorice(Gancao) and Jujube(Dazao), is a traditional Chinese medicine prescription, originated from treatise on Febrile Diseases, has the functions of clearing heat, stopping benefits and relieving pain. It is the original prescription for treating heat and relieving dysentery, and is commonly used in clinic for diarrhea and other diseases. In ulcerative colitis, damp-heat syndrome is the most common. However, its mechanism of action is not completely clear.The purpose of the research is to investigate the protective effect of HQD on ulcerative colitis rats and the regulation effect of mitochondrial DNA, TLR4, p-Akt, p-PI3K protein and microbiota.The effects of HQD anti-UC were investigated by fluorescence quantitative PCR, cytokine level and histopathological analysis in DSS-induced ulcerative colitis (UC) rats. The content of mtDNA in colon epithelial cells of rats in each group was detected by fluorescence quantitative PCR, p-PI3K, p-Akt and TLR4 protein expressions in colon tissues of rats in each group were detected by Western blotting. IL-6, IL-17 and IL-23 inflammatory factors were detected by ELISA. The effect of HQD on intestinal microbiota of rats with ulcerative colitis was studied by high-throughput sequencing technology, and the correlation between mtDNA level and inflammatory factors as well as protein expression in colonic epithelium of rats with ulcerative colitis was analyzed by SPSS23.0.HQD significantly alleviated UC symptoms by improving the mucosal intestinal epithelial cell structure, mental state, hair gloss, fecal occult blood, lamina propria intestinal glands and inflammatory cell infiltration. And HQD reduced the pro-inflammatory cytokines in the colonic epithelium of UC rats Production of IL-6, IL-17 and IL-23. The HE stained section of colon tissue showed a complete intestinal epithelial mucosal layer structure. The structure of epithelial cells was more normal and abundant. There were more goblet cells in lamina propria adenoma, which improved the infiltration of inflammatory cells. HQD significantly inhibited the mtDNA content in rat colonic epithelial tissue, and significantly inhibited the expression of TLR4, p-PI3K and p-Akt inflammatory signaling pathways. The results of the microbiota experiment showed that the abundance of HQD in the phylum Firmicutes increased, and the number of Bacteroides phylum decreased (p < 0.05). At the genus level, HQD significantly increased Lactobacillus and Firmicutes Bacteroides, while Treponema and Bacteroides were significantly reduced (p < 0.05).HQD has a certain protective effect on rats with damp heat ulcerative colitis. Its mechanism may be related to regulating the expression of p-PI3K, p-Akt and TLR4 proteins, mitochondrial DNA as well as microbiota.