[Effect of total saponins from Panax japonicus on non-alcoholic steatohepatitis by regulating autophagy].

ABSTRACT

Non-alcoholic steatohepatitis(NASH) was induced by high-sugar and high-fat diet in mice to investigate the intervention effect of total saponins from Panax japonicus(TSPJ) and explore its possible mechanism. Mice were fed with high-sugar and high-fat diet to establish NASH model, and intervened with different doses of TSPJ(15, 45 mg·kg~(-1)). The animals were fed for 26 weeks. The histomorphology and pathological changes of liver tissues were observed by HE staining. The transcriptional expression levels of miR-199 a-5 p, autophagy related gene 5(ATG5) and inflammatory cytokines interleukin-6(IL-6), interleukin-1ß(IL-1ß) and tumor necrosis factor α(TNF-α) in mouse liver were measured by quantitative Real-time polymerase chain reaction(qRT-PCR). Western blot was used to detect the expression of autophagy-related proteins ATG5, P62/SQSTM1(P62), and microtubule-associated protein light chain 3(LC3)-I/Ⅱ proteins in mouse liver. The expression of P62 protein was detected by immunofluorescence staining. In order to verify the targeting regulation relationship between miR-199 a-5 p and ATG5, miR mimic/inhibitor NC and miR-199 a-5 p mimic/inhibitor were transfected into Hepa 1-6 cells, and the expression of ATG5 mRNA and protein was detected. pMIR-reportor ATG5-3'UTR luciferase reporter gene plasmid was constructed and co-transfected with miR mimic/inhibitor NC and miR-199 a-5 p mimic/inhibitor into Hepa 1-6 cells to detect luciferase activity. In vivo, HE staining in the model group showed typical fatty degeneration and inflammatory infiltration, with increased expression of miR-199 a-5 p and decreased expression of ATG5 mRNA and protein. The expression of autophagy-associated protein P62 increased significantly, the ratio of LC3Ⅱ/Ⅰ decreased, and the transcriptional expression of inflammatory factors increased significantly. After the intervention by TSPJ, the pathological performance of liver tissue was significantly improved, the expression of miR-199 a-5 p decreased and the expression of ATG5 mRNA and protein increased, the expression of autophagy-associated protein P62 decreased significantly, the ratio of LC3Ⅱ/Ⅰ increased, and the transcriptional expression of inflammatory cytokines IL-6, IL-1ß and TNF-α decreased significantly. In vitro, it was found that the expression of ATG5 mRNA and protein and luciferase activity decreased significantly in miR-199 a-5 p overexpression cells, while after inhibition of miR-199 a-5 p expression, the expression level of ATG5 mRNA and protein and luciferase activity increased. The results showed that TSPJ can improve NASH in mice fed with high-sugar and high-fat diet, and its mechanism may be related to the regulation of miR-199 a-5 p/ATG5 signal pathway, the regulation of autophagy activity and the improvement of inflammatory response of NASH.