Aureusidin protects against osteoarthritis via Caspase-3/gasdermin E-mediated pyroptosis

This study investigated the effects of Aureusidin on extracellular matrix (ECM) degradation and pyroptosis of chondrocytes in osteoarthritis. Network pharmacology, molecular docking, and pull-down assays were initially conducted to explore the target of Aureusidin. Subsequently, Sprague-Dawley rats underwent anterior cruciate ligament transection (ACLT) received oral administration of Aureusidin. Cartilage damage was evaluated histopathologically by H&E and Safranin O-fast green staining. Primary rat chondrocytes were treated with Aureusidin under IL-1β stimulation. Pyroptotic morphology was observed under light microscopy. Propidium iodide staining and flow cytometry were conducted to evaluate membrane rupture. The expression of markers associated with ECM degradation and pyroptosis was analyzed by qRT-PCR, Western blot, immunohistochemistry, and ELISA. Caspase-3 was identified as a target for Aureusidin. Aureusidin (5, 10, 20 mg/kg) alleviated ACLT-induced cartilage damage and ECM degradation. It reduced the OARSI score and serum levels of CTX-II and COMP, while upregulating the expression of Col2a1 and Acan, and downregulating Adamts5, Mmp13, and Mmp3. Aureusidin also mitigated atypical pyroptosis, evidenced by inhibited expression of GSDME-N, Caspase-3, and Cleaved-Caspase-3, and decreased levels of IL-1β and IL-18. In IL-1β-stimulated primary chondrocytes, Aureusidin (5, 10, 20 μM) attenuated ECM degradation and Caspase-3/GSDME-mediated pyroptosis. Treating chondrocytes with the Caspase-3 inhibitor Z-DEVD-FMK under IL-1β-stimulated conditions alleviated ECM degradation and pyroptosis, but the additional application of Aureusidin did not provide further inhibition. Aureusidin has the potential to inhibit ECM degradation and Caspase-3/GSDME-mediated chondrocyte pyroptosis during osteoarthritis progression. Its therapeutic effects are dependent on binding to and modulating the Caspase-3.