[Mechanism of action of Zhengqing Fengtongning Sustained-release Tablets for treatment of knee osteoarthritis based on metabolomics and intestinal flora]

In order to elucidate the therapeutic effect and mechanism of action of Zhengqing Fengtongning Sustained-release Tablets on knee osteoarthritis, this study created a knee osteoarthritis model using 0.2 mL 40 g·L~(-1) papain and randomly divided the rats into the model group, high-dose and low-dose groups of Zhengqing Fengtongning Sustained-release Tablets, and celecoxib group. All groups were given the drug for four weeks, with the diameter of their knee joint being measured during this period. Hematoxylin-eosin staining and Senna solid green staining were utilized to observe the pathology of knee joint tissue in SD rats. The initial therapeutic impact of Zhengqing Fengtongning Sustained-release Tablets on knee osteoarthritis in rats was assessed by monitoring the levels of interleukin-1β(IL-1β) and interleukin-6(IL-6) in the plasma. Using a combination of non-targeted metabolomics and 16S rRNA techniques, researchers determined the variations in endogenous molecules and intestinal flora in rats and identified potential biomarkers. The results showed that Zhengqing Fengtongning Sustained-release Tablets improved the diameter of knee joint swelling, ameliorated the pathological damage of cartilage tissue, and reduced the plasma levels of IL-1β and IL-6 in rats with knee osteoarthritis. Metabolomics analysis identified 22 potential biomarkers associated with the modulatory effects of Zhengqing Fengtongning Sustained-release Tablets, including 5-hydroxytryptamine, corticosterone, methylmalonic acid, and other biomarkers, which were mainly involved in eight metabolic pathways, including tryptophan metabolism, vitamin K metabolism, steroid synthesis, and so on. The results of intestinal flora showed a decrease in the diversity of intestinal flora in the model group, an increase in the diversity of intestinal flora, and an improvement in the microecology of intestinal flora. Significant differences were found in Lachnospiraceae＿NK4A136＿group, Helicobacter, Lactobacillus, Bacteroides, and Parabacteroides. Finally, the results of the combined analysis showed that 22 biomarkers were correlated with five genera. The above results indicate that Zhengqing Fengtongning Sustained-release Tablets can improve the tissue morphology and structure of knee joints, reduce the level of plasma inflammatory factors, regulate the diversity of intestinal flora, and balance the metabolic pathways of steroid synthesis, vitamin K metabolism, and tryptophan metabolism to exert a therapeutic effect on knee osteoarthritis.