Integrative Multi-Omics Analysis Identifies GZMK as a Causal and Druggable Target in Knee Osteoarthritis

Background: Osteoarthritis (OA) is the most prevalent degenerative joint disease worldwide and causing significant pain and disability, particularly in older adults. It is characterized by articular cartilage degradation, synovial inflammation, and subchondral bone remodeling. Methods: This study elucidated the molecular mechanisms driving OA pathogenesis using an integrative multi-omics approach, combining bulk and single-cell RNA sequencing with genetic association analyses, including Summary-data-based Mendelian Randomization (SMR) and Bayesian colocalization analysis, and molecular docking to investigate key molecular drivers of knee OA. Patient samples with different degenerative degrees of OA were also used for relevant verification. Results: We identified GZMK as a central gene linking transcriptional dysregulation with genetic susceptibility in both synovium and cartilage of knee OA. GZMK, a serine protease expressed by cytotoxic lymphocytes, was found to be significantly associated with OA progression through genetic analyses and experimental verification. Single-cell RNA sequencing revealed that GZMK was predominantly expressed in T cells within the synovial tissue. Molecular docking simulations identified potential small-molecule inhibitors targeting GZMK, with Monoisopropylphosphorylserine and O-Benzylsulfonyl-Serine showing favorable binding affinities. Conclusions: This study identified GZMK as a key driver linking transcriptional dysregulation and genetic susceptibility in OA. The identification of potential small-molecule inhibitors targeting GZMK through molecular docking further supports its druggability. Future work should focus on functional validation of GZMK's role in OA progression and preclinical testing of candidate inhibitors to explore its potential in therapeutic intervention.