[Study on mechanism of Rehmanniae Radix Praeparata for treatment of osteoarthritis based on network pharmacology and molecular docking].

The mechanism of Rehmanniae Radix Praeparata against osteoarthritis was investigated based on network pharmacology, molecular docking, and in vitro experiments in the present study. Osteoclast models were established via receptor activator of nuclear factor-κB ligand(RANKL) and macrophage colony-stimulating factor(M-CSF) inducing RAW264.7 cells. Further, the influence of Rehmanniae Radix Praeparata on the activity of tartrate-resistant acid phosphatase(TRAP) was evaluated and the efficacy of Rehmanniae Radix Praeparata in the treatment of osteoarthritis was verified. The active components of Rehmanniae Radix Praeparata were obtained from Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform(TCMSP) and literature, and the potential targets of the components were collected from SwissTargetPrediction. Osteoarthritis disease targets were searched in Online Mendelian Inheritance in Man(OMIM), Therapeutic Target Database(TTD), GeneCards, and DisGeNET. The intersection targets of Rehmanniae Radix Praeparata and osteoarthritis were obtained by Venny platform. The protein-protein interaction(PPI) network was constructed by Cytoscape 3.8.2, and key targets were obtained based on topology algorithm. The Database for Annotation, Visualization and Integrated Discovery(DAVID) was used to perform Gene Ontology(GO) and Kyoto Encyclopedia of Genes and Genomes(KEGG) pathway enrichment analysis. Finally, the mRNA expression of the key targets was determined by RT-qPCR and the binding activity between the components and key targets was validated by molecular docking. The results showed that Rehmanniae Radix Prae-parata inhibited the TRAP activity, thus inhibiting bone resorption by osteoclasts and treating osteoarthritis. By network pharmacology, 14 active components of Rehmanniae Radix Praeparata and 126 intersection targets were obtained. The network pharmacology enrichment results revealed 432 biological processes and 139 signaling pathways. Key targets such as proto-oncogene tyrosine-protein kinase Src(SRC), signal transducer and activator of transcription 3(STAT3) and transcription factor p65(RELA) were obtained according to the degree in topological analysis. SRC was highly expressed in osteoclasts, which accelerated the development of osteoarthritis. Therefore, SRC was selected for subsequent verification, and Rehmanniae Radix Praeparata decreased the gene expression level of SRC. The molecular docking showed that acteoside, isoacteoside, raffinose had good bonding activity with SRC, suggesting that they might be the critical components in treating osteoarthritis. In conclusion, Rehmanniae Radix Praeparata can inhibit bone resorption by osteoclasts and balance the metabolism of articular cartilage and subchondral bone via acting on SRC, thus playing a therapeutic role in osteoarthritis. In addition, Rehmanniae Radix Praeparata may exert overall efficacy on osteoarthritis through other targets such as STAT3 and RELA, and other related pathways such as PI3 K-AKT and IL-17 signaling pathways.