Network pharmacology-based approach to research the effect and mechanism of Si-Miao-Yong-An decoction against thromboangiitis obliterans

Background Si-Miao-Yong-An decoction (SMYAD) is a conventional therapeutic formula for treat thromboangiitis obliterans (TAO), consisting of four Chinese herbs: Lonicerae japonicae Thunb. (Jinyinhua), Scrophularia ningpoensis Hemsl. (Xuanshen), Angelica sinensis (Oliv.) Diels (Danggui) and Glycyrrhiza uralensis Fisch. (Gancao). However, the mechanism of SMYAD in TAO treatment remains unclear.Methods Components, as well as potential targets of SMYAD in TAO therapy, were downloaded from Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP). Subsequently, with the Database for Annotation, Visualization, and Integrated Discovery (DAVID) server, the gene ontology (GO) biological processes and the Kyoto encyclopedia of genes and genomes (KEGG) signalling pathways of the targets enrichment were performed. Next, based on STRING online database, the protein interaction network of vital targets was built and analysed. Molecular docking and calculation of the binding affinity were performed using AutoDock. The PyMOL software was employed to observe docking outcomes of active compounds and protein targets. Based on the predicted outcomes of network pharmacology, in vivo and in vitro tests were performed for validation. In vivo experiment, the TAO rats model was established using sodium laurate injection into the femoral artery. The symptoms as well as pathological changes of the femoral artery were observed. Besides, the predicted targets were verified by the RT-qPCR, in vitro experiment. The cell viability in LPS-induced human umbilical vein endothelial cells (HUVECs) was detected using CCK-8 kit, and the predicted targets were also verified by the RT-qPCR.Results In the network pharmacology analysis, we obtained 105 chemical components in SMYAD and 24 therapeutic targets. We found that the mechanism SMYAD in TAO therapy was primarily associated with inflammation and angiogenesis by constructing multiple networks. Quercetin, vestitol and beta-sitosterol were important compounds, and interleukin-6 (IL6), MMP9, and VEGFA were key targets. According to molecular docking, active compounds (quercetin, vestitol and beta-sitosterol) and targets (IL6, MMP9 and VEGFA) showed good binding interactions. In in vivo experiment, SMYAD ameliorated the physical signs and pathological changes, inhibited the expression of IL6 and MMP9, and enhanced the expression of VEGFA. In an in vitro experiment, SMYAD increased the cell viability of LPS-induced HUVECs and the expression of VEGFA, and reduced the expression of IL6 and MMP9.Conclusions This study showed that SMYAD improves TAO symptoms and inhibits the development of TAO. The mechanism could be associated with anti-inflammatory and therapeutic angiogenesis.