Immune Gene INHBA Drives Osteoarthritic Cartilage Damage via Temporal TGF-β/p38 MAPK Pathway Activation

Osteoarthritis (OA) is a debilitating degenerative joint disorder characterized by cartilage degeneration, with immune-inflammatory regulation playing a critical, yet incompletely understood, role in its pathogenesis. Current standard-of-care often addresses symptoms rather than underlying mechanisms, highlighting a need for precision diagnostics and targeted interventions. This study addresses the gap by identifying core immune genes and elucidating their temporal activation of key signaling pathways, specifically focusing on the TGF-β/p38 MAPK pathway, to provide a theoretical basis for novel therapeutic strategies.

Researchers downloaded 4 sets of OA cartilage transcriptomic datasets from the GEO database, including normal controls (NCs). After batch correction, a training set and 2 independent validation sets were constructed to screen immune-related differentially expressed genes (Immune-DEGs). A total of 113 combined models were built using 12 basic machine learning algorithms, optimized via 10-fold cross-validation. Core immune genes were identified by integrating Shapley additive explanations (SHAP) analysis and weighted gene coexpression network analysis (WGCNA). Single-cell pseudotime analysis deciphered dynamic expression patterns. Finally, RT-qPCR and western blot (WB) verified core gene and pathway protein expression in cell models and OA animal cartilage tissues. Drug repurposing was conducted using the DSigDB database, with molecular docking and dynamics simulations validating drug binding to core targets.

A total of 12 immune-DEGs significantly associated with OA were screened. Through systematic evaluation of multiple models, an exploratory OA classification model based on 10 important immune genes was constructed, showing good classification performance. Functional enrichment analysis revealed significant involvement of immune-related pathways. Integrating SHAP and WGCNA identified INHBA as a core immune gene, whose dynamic expression during OA progression was elucidated by single-cell pseudotime analysis. Experimental validation via RT-qPCR and western blot confirmed that INHBA expression was significantly altered in OA cell models and animal cartilage tissues with varying lesion severities. Critically, INHBA was found to mediate the temporal activation of the TGF-β/p38 MAPK signaling pathway. Drug repurposing and molecular docking identified potential therapeutic compounds with strong binding affinity to INHBA and related targets.

INHBA was identified as a core immune gene mediating the temporal activation of the TGF-β/p38 MAPK pathway, directly linking immune regulation to OA cartilage damage progression.