Thrombin induces degradation of murine intervertebral discs via angiogenesis and M1-like polarization of macrophages

With the marked aging of the global population, the prevalence of musculoskeletal disorders owing to low back pain has escalated, with an associated increase in the number of individuals requiring nursing care. To help identify novel therapies for treating disc degeneration, we examined the roles of thrombin and macrophages in intervertebral disc degeneration, a significant cause of low back pain. Experiments using a needle-puncture mouse model of disc degeneration confirmed that this process led to the production of thrombin and MCP-1. Thrombin altered macrophage markers, increasing the population of M1 markers and decreasing that of M2 markers. Therefore, increased thrombin and MCP-1 production may induce disc degeneration by inducing M1-type polarization of migrated macrophages. Disk-tissue M1-macrophage levels were elevated 3 weeks after puncture. Administering SCH79797, a thrombin receptor (PAR1) antagonist, suppressed thrombin-induced disc degeneration and inhibited macrophage migration, M1 polarization, VEGF production, and angiogenesis. These findings suggest the suppression of thrombin function in intervertebral disc inflammation as a novel and promising approach for treating disc degeneration.