Verification of pain-related neuromodulation mechanisms of icariin in knee osteoarthritis

Knee osteoarthritis (KOA) is a common disease with no specific treatment. Icariin (ICA) is considered an agent for KOA. This study aimed to confirm the pain-related neuromodulation mechanisms of ICA on KOA. Three experiments were designed: (1) verifying the therapeutic effects of ICA in vivo and in vitro, (2) exploring the potential pain-related neuromodulation pathways involved in ICA treatment by functional magnetic resonance imaging (fMRI) and virus retrograde tracing (VRT) and (3) confirming the pain-related targets by tandem mass tag (TMT)-based quantitative proteomics and bioinformatic analyses. Experiment 1 verified the efficacy of ICA in OA animal and cell models. Experiment 2 found a series of brain regions associated with KOA reversed by ICA treatment, indicating that a pain-related hypothalamic-mediated neuromodulation pathway and an endocannabinoid (EC)-related pathway contribute to ICA mechanisms. Experiment 3 explored and confirmed four pain-related genes involved in KOA and ICA treatment. We confirmed the key role of pain-related neuromodulation mechanisms in ICA treatment associated with its analgesic effect. Our findings contribute to considering ICA as a novel therapy for KOA.