Exposure to second-hand cigarette smoke exacerbates the progression of osteoarthritis in a surgical induced murine model

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.

The Causal Association between Alcohol, Smoking, Coffee Consumption, and the Risk of Arthritis: A Meta-Analysis of Mendelian Randomization Studies

Objective: To evaluate the genetic causality between alcohol intake, smoking, coffee consumption, and arthritis. Methods: Mendelian randomization (MR) studies with alcohol, smoking, and coffee consumption behaviors as exposures, and osteoarthritis (OA) and rheumatoid arthritis (RA) as outcomes were retrieved from up to July 2023. Two researchers with relevant professional backgrounds independently assessed the quality and extracted data from the included studies. Meanwhile, we applied MR analyses of four lifestyle exposures and five arthritis outcomes (two for OA and three for RA) with gene-wide association study (GWAS) data that were different from the included studies, and the results were also included in the meta-analysis. Statistical analyses were performed using Stata 16.0 and R software version 4.3.1. Results: A total of 84 studies were assessed. Of these, 11 were selected for meta-analysis. As a whole, the included studies were considered to be at a low risk of bias and were of high quality. Results of the meta-analysis showed no significant genetic causality between alcohol intake and arthritis (odds ratio (OR): 1.02 (0.94-1.11)). Smoking and arthritis had a positive genetic causal association (OR: 1.44 (1.27-1.64)) with both OA (1.44 (1.22-1.71)) and RA (1.37 (1.26-1.50)). Coffee consumption and arthritis also had a positive genetic causal association (OR: 1.02 (1.01-1.03)). Results from the subgroup analysis showed a positive genetic causality between coffee consumption and both OA (OR: 1.02 (1.00-1.03)) and RA (OR: 1.56 (1.19-2.05)). Conclusion: There is positive genetic causality between smoking and coffee consumption and arthritis (OA and RA), while there is insufficient evidence for genetic causality between alcohol intake and arthritis.