Therapeutic Effect of Huzhangoside D in Rats with Knee Osteoarthritis Induced by Anterior Cruciate Ligament Transection

Background: Knee osteoarthritis (KOA) is an age‑related disease. Huzhangoside D is a saponin isolated from genus Clematis L. (Ranunculaceae). The aim of this study is to explore the anti‑inflammatory, apoptotic, and autophagy regulation effects of huzhangoside D on KOA in a rat model. Materials and Methods: The KOA model was established by an anterior cruciate ligament transection surgery. Huzhangoside D was administered for 4 weeks. The weight‑bearing assay, morphology observation, and intrinsic mechanism exploration were performed. Results: After administration, the weight‑bearing assay showed that huzhangoside D promoted joint function recovery. Hematoxylin‑eosin and safranin O‑Fast green staining indicated that huzhangoside D ameliorated the structural damage. The Mankin scores were decreased in the huzhangoside D groups. Huzhangoside D enhanced cartilage thickness. Enzyme‑linked immunosorbent assay study revealed that huzhangoside D downregulated the proinflammatory cytokine (tumor necrosis factor alpha, interleukin‑6, and interleukin‑1β) levels, while it upregulated the anti‑inflammatory cytokine (interleukin‑10) level in rat serum. Terminal deoxynucleotidyl transferase dUTP nick end labeling assay showed that huzhangoside D downregulated the apoptosis ratio of cartilage cells. Immunohistochemical staining showed that huzhangoside D upregulated the autophagy‑related protein beclin‑1, ATG5, ATG7, and light chain 3 levels and downregulated the p62 level. Moreover, the AKT and mTOR signaling pathway activities were downregulated. The 3‑MA combination with huzhangoside D downregulated the weight‑bearing function and morphology of the knee and upregulated the proinflammatory cytokines, which showed the role of autophagy as a protective mechanism in the effect of huzhangoside D. Conclusion: This study revealed that huzhangoside D is a promising agent in KOA treatment.