Bushen Yijing formula exerts chondroprotective effects in knee osteoarthritis via the ERα/PI3K/AKT signaling pathway: Insights from network pharmacology and experimental validation.

PURPOSE: The aim of this study is to reveal the molecular mechanisms of BSYJF in KOA treatment through bioinformatics, animal and cellular experiments.

METHODS

Network pharmacology identified BSYJF's potential active ingredients and targets for KOA treatment, predicting its mechanism of action. In vivo, rats underwent anterior cruciate ligament transection (ACLT) to induce KOA. The therapeutic efficacy of BSYJF was subsequently evaluated using enzyme-linked immunosorbent assay (ELISA), immunohistochemical staining, and micro-computed tomography (Micro-CT). In vitro, chondrocytes were treated with IL-1β to establish an inflammatory model, and BSYJF's protective mechanisms for chondrocytes were subsequently assessed by immunostaining, Western blot (WB), and Reverse Transcription Quantitative Polymerase Chain Reaction (RT-qPCR). Furthermore, we evaluated the binding affinities of its potential active constituents to identified targets using molecular docking.

RESULTS

Network pharmacology identified 50 active ingredients in BSYJF and 46 hub targets associated with KOA treatment. BSYJF administration significantly reduced serum levels of KOA-related factors (CTX-II, VEGF-A, TNF-α, IL-1β, IL-6) and alleviated abnormal subchondral bone remodeling, as indicated by Micro-CT. Moreover, it downregulated the expression of iNOS and MMP-3 while upregulating Acan and Col2α1 in cartilage tissue, thereby attenuating articular cartilage degeneration. BSYJF-containing serum alleviated IL-1β-induced chondrocyte damage, restoring anabolic markers (Col2α1, Acan, SOX-9) while suppressing catabolic/inflammatory mediators (MMP-3/9/13, ADAMTS5, COX2, VEGF, IL-1β, TNF-α, IL-6). Mechanistically, BSYJF reversed the IL-1β-mediated suppression of ERα expression and PI3K/AKT phosphorylation. This restorative effect was abolished by Fulvestrant (ERα inhibitor), whereas LY294002 (PI3K inhibitor) blocked downstream signaling activation without affecting ERα. RT-qPCR results further confirmed that BSYJF corrected IL-1β-induced dysregulation of targets associated with the PI3K/AKT and estrogen signaling pathways (AKT1, BCL2, MAPK3, EGFR, and ESR1) ERα-dependent manner.

CONCLUSION

This study demonstrates that BSYJF attenuates KOA progression by regulating the ERα/PI3K/AKT signaling pathway. This multi-targeted action ameliorates cartilage degradation and aberrant bone remodeling, positioning BSYJF as a comprehensive therapeutic agent for KOA.