Cycloastragenol attenuates osteoarthritis by restoring chondrocyte senescence via the NRF2/NF-κB signaling axis

Osteoarthritis (OA) involves oxidative stress-induced chondrocyte senescence and extracellular matrix (ECM) dysregulation, yet disease-modifying therapies remain elusive. This study investigates the effects of cycloastragenol (CAG), a telomerase-activating triterpenoid from Astragalus membranaceus, on OA progression with a focus on NRF2/NF-κB signaling. In vitro, CAG suppressed oxidative stress-induced senescence in primary rat chondrocytes, evidenced by reduced SA-β-gal positivity, partially restored EdU proliferation, and downregulated senescence related proteins expression. In addition, CAG concurrently attenuated senescence-associated secretory phenotype (SASP) and partially restored ECM homeostasis. Mechanistically, molecular docking analysis suggested a potential interaction between CAG and the Kelch domain of KEAP1. Consistent with this, CAG treatment was associated with NRF2 pathway activation and attenuation of TBHP-induced NF-κB signaling. Importantly, genetic inhibition of NRF2 significantly attenuated the protective effects of CAG, supporting a required role for NRF2 in mediating CAG-induced suppression of oxidative stress and inflammatory signaling. In vivo, intra-articular CAG administration in monosodium iodoacetate (MIA)-induced OA rats reduced cartilage degradation, rescued ECM homeostasis, and enhanced NRF2 activation. Collectively, CAG mitigates the degradation of the extracellular matrix and suppresses the senescence-associated secretory phenotype (SASP) induced by osteoarthritis (OA).