Hui Medicine Moxibustion Improves Knee Osteoarthritis in Rabbits by Regulation of OPG/RANKL/RANK System

Abstract

Background: The osteoprotegerin (OPG)/receptor activator of nuclear factor-kappa B (RANK)/RANK ligand (RANKL) system is closely related to knee osteoarthritis (KOA) subchondral bone osteosclerosis. As a heat-sensitive therapy, Hui Medicine moxibustion (HMm) has a good therapeutic effect on KOA. This study focused on the OPG/RANKL/RANK signaling pathway in KOA subchondral bone reconstruction, and explored the mechanism of HMm action on the reconstruction of KOA subchondral bone. Methods: KOA models were established via Hulth method, and treated with HMm and HMm together with OPG antagonist (anti-OPG antibody). Hematoxylin-eosin staining and toluidine blue staining were used to characterize the pathological features of tibia. The apoptosis of osteoclasts and osteoblasts were detected by double immunofluorescence. The expression of OPG, RANKL and RANK were detected by immunohistochemistry, Real-Time Polymerase Chain Reaction (RT-PCR) and western blotting. In addition, RT-PCR and western blotting were used to detect matalloproteinase 3 (MMP-3), matalloproteinase 9 (MMP-9), interleukin 1 (IL-1), type I collagen (COL I) and osteopontin (OPN). Hydroxyproline, hexosamine, aggrecan and calcium were detected by corresponding kit. Results: After HMm treatment, the loss of cartilage and subchondral bone were significantly decreased. HMm treatment also increased the ratio of apoptotic osteoclasts to apoptotic osteoblasts. Compared with KOA group, HMm treatment promoted the protein level of OPG and decreased the protein level of RANKL. In addition, the expression levels of MMP-3, MMP-9 and IL-1 were markedly decreased and OPN was increased. The components of subchondral bone (hydroxyproline, hexosamine, aggrecan and calcium) were significantly promoted in the Hui/KOA group. However, OPG antagonist alleviated these effects of HMm treatment. Conclusions: HMm treatment may improve subchondral bone in KOA by regulating the osteoprotegerin (OPG)/receptor activator of nuclear factor-kappa B (RANK)/RANK ligand (RANKL) system. This study may provide a basis for KOA treatment.