Uncovering the mechanisms of homologous point acupuncture on knee osteoarthritis through an integrated study of metabolomics and proteomics

<h4>Background</h4>The incidence and prevalence of knee osteoarthritis (KOA) are on the rise, with the intricate etiology and pathogenesis of the disease posing significant challenges to global health. Although acupuncture has significant promise in modulating the body's metabolism and inflammatory reactions, the efficacy of various acupuncture methods for treating KOA remains uncertain. In this research, we evaluated the efficacy of homologous point acupuncture compared to conventional acupuncture for KOA and investigated the potential therapeutic mechanisms of homologous point acupuncture through a rat model.<h4>Methods</h4>Rat models of KOA were established by intra-articular injection of monosodium iodoacetate. The successfully modeled rats were allocated into three groups: KOA group (model group, injected with MIA), conventional acupuncture group (AP), and homologous point acupuncture group (HAP). Additionally, healthy rats were designated as a normal control group (Control), with ten rats in each group. Following 4 weeks of consecutive acupuncture treatment, joint swelling and Lequesne MG scores were assessed in each group of rats. Subsequently, blood samples were obtained from the abdominal aorta to assess the expression levels of IL-6, IL-1β, TNF-α, and LDH. Integrated metabolomics and proteomics reveal the mechanism of homologous point acupuncture in KOA rats. Validation of these mechanisms included staining with hematoxylin and eosin, ELISA, biochemical kit, and Western blotting.<h4>Results</h4>Behavioral assessments revealed that, compared to the control group, Lequesne MG scores and degree of joint swelling were significantly increased in the KOA group, whereas both AP and HAP treatment significantly decreased these parameters. Histopathological examination indicates that the cartilage layer in KOA rat models exhibits thinning, irregular surface texture, and indistinct tidemark. In contrast to the KOA group, both AP and HAP exhibited reduced articular cartilage surface irregularity and mitigated cartilage degeneration, and a notable decrease in the levels of IL-6, IL-1β, TNF-α, and LDH in the rat serum following treatment. Further analysis through metabolomics and proteomics reveal that HAP exerts its therapeutic effects by modulating pathways associated with immunity and metabolism, with specific emphasis on Arachidonic acid metabolism and glycolytic processes. Western blot analysis demonstrated that HAP decreased the expression levels of proteins involved in glycolysis, NLRP3 inflammasome activation, and autophagy and apoptosis, and increased the levels of proteins that promote autophagy and prevent apoptosis.<h4>Conclusion</h4>HAP significantly reduced pain-related responses and joint swelling in KOA rats. Specifically, HAP manifests inhibitory effects on inflammatory response in KOA and alleviates knee joint damage in a rat model. These effects are associated with the modulation of glycolysis, NLRP3 inflammasome activation, autophagy, and apoptosis. However, due to the absence of a sham acupuncture control, the specific therapeutic contribution of needling itself cannot be distinguished from non-specific effects.