Preliminary study on the potential damage of cigarette smoke extract in 3D human chondrocyte culture

Osteoarthritis (OA) is a chronic degenerative disease characterized by the progressive loss of articular cartilage. The role of cigarette smoke (CS) in OA is debated, with some studies suggesting a protective effect while others indicate it may pose a risk. Our preliminary findings suggest a link between smoking in young adults and severe knee OA, though the extent of this contribution is unclear. This study investigates the impact of cigarette smoke extract (CSE) on human chondrocytes. Human chondrocyte cultures were exposed to varying concentrations (0-10%) of CSE for 7 d. We evaluated cell viability, extracellular matrix (ECM) components, metalloproteinase expression and cytokines levels, and antioxidant enzymes (SOD1 and CAT) using calcein staining, immunohistochemistry and ELISA. Oxidative stress (OS) was assessed by measuring hydrogen peroxide (H₂O₂) and nitric oxide (NO) levels. Results were analyzed using ANOVA with Tukey post hoc tests, and Pearson correlation coefficients were calculated. Cell viability decreased at 10% CSE, and ECM components were diminished. MMP9 and MMP13 expression significantly increased at 5% and 10% CSE. H₂O₂ levels peaked at 1%, while IL-1β peaked at 2.5%. Antioxidant expression (SOD1 and CAT) decreased at higher concentrations, and heat shock protein 70 (HSP70) was notably expressed. MMPs expression was negatively correlated with both viability and ECM components. CSE induces cellular damage, alters ECM composition, and upregulates MMP expression via OS and IL-1β, while diminishing antioxidant defenses. These findings suggest that smoking may disrupt articular cartilage homeostasis, highlighting the need for further investigation into oxidative stress and inflammatory mediators.