Integration of Network Pharmacology, Molecular Docking, and Experimental Validation to Identify the Effect of EGCG on Alleviating Chondrocyte Inflammatory Damage by Targeting ER Stress-STAT3 Crosstalk.

BACKGROUND: Osteoarthritis (OA) is the most common joint disorder and a major global health burden. Epigallocatechin-3-gallate (EGCG), a green tea-extracted polyphenol, shows therapeutic potential for OA, but a comprehensive understanding of its mechanisms is essential to enhance clinical utility. METHODS: EGCG-related targets were identified utilizing the TCMSP, BATMAN-TCM, PharmMapper, and SwissTargetPrediction databases. OA-related targets were retrieved from GeneCards, DisGeNET, OMIM, and TTD databases. A protein-protein interaction (PPI) network was constructed using Cytoscape 3.10.1, and the CytoNCA plugin was used for topological analysis to identify the core targets. To clarify EGCG's therapeutic mechanisms in OA, we performed systematic functional annotation via Gene Ontology (GO) enrichment and interrogated relevant biological pathways using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. Furthermore, molecular docking was applied to assess the binding affinity between EGCG and key targets. Finally, in vitro experiments using primary chondrocytes stimulated with IL-1β were conducted to validate the predictions from network pharmacology. RESULTS: 488 EGCG-related targets were identified, with 172 overlapping OA-related genes. Four core genes were identified, including STAT3, TP53, AKT1, and JUN. GO enrichment analysis revealed 2163 biological processes, 92 cellular components, and 223 molecular functions; KEGG analysis identified 175 enriched signaling pathways. Molecular docking showed EGCG's binding affinity to core target STAT3 was approximately -8.1 kcal/mol. In vitro experiments showed that EGCG reduced IL-1β-induced catabolic and inflammatory responses in chondrocytes, which is linked with attenuated endoplasmic reticulum (ER) stress. Moreover, the involvement of STAT3 in the effects of EGCG that alleviate ER stress in OA has been established, highlighting its therapeutic potential. CONCLUSION: This study reveals that EGCG may ameliorate the metabolic imbalance of extracellular matrix (ECM) and inflammatory responses by modulating the activity of the ER stress-STAT3 crosstalk.