[Mechanism of Potentilla discolor in treating UC by regulating mitochondrial autophagy]

To evaluate the therapeutic effect of Potentilla discolor on 2,4,6-trinitrobenzensulfonic acid(TNBS)-induced experimental ulcerative colitis(UC) in rats and to determine its therapeutic mechanism through mitochondrial autophagy, immune cells, and cytokines. A rat model of UC was established by TNBS-ethanol enema. Rats were divided into six groups: control, UC model, sulfasalazine(positive drug), and high-dose, moderate-dose, and low-dose ethanol extract groups. After 14-day continuous administration of the corresponding drugs, the disease activity index(DAI) and hematoxylin and eosin(HE) were evaluated. The morphological structure of mitochondria was observed by using transmission electron microscope(TEM), mitophagy-related mRNA expression was detected by using Real-time quantitative polymerase chain reaction(qRT-PCR), immune cell differentiation in rat serum was detected by using flow cytometry(FCM), and cytokine expression in colon tissues of rats was detected by protein microarray. The results showed that compared with the model group, each dose group of P. discolor could significantly reduce the DAI of UC model rats, and decrease the degree of inflammatory cells infiltration in the colon tissue of UC model rats. Meanwhile the expressions of T cells and Th cells in the serum increased significantly, the expression of Tc cells in the serum decreased significantly. Transmission electron microscope found that there was fusion of mitochondria and lysosomes in the colon tissue of the administration group. The expressions of mitochondrial autophagy related genes NF-κB, p62 and parkin were significantly increased in colon tissues. The results of protein chip showed that compared with the model group, the high dose group of P. discolor could significantly regulate the expression of cytokines. In conclusion, these results suggested that P. discolor improved TNBS-induced acute ulcerative colitis in rats by regulating the mitochondrial autophagy and the inflammatory factor expression.