Smoking has been associated, among other factors, with musculoskeletal disorders. Although there is no consensus about the effects of smoking on osteoarthritis (OA), the increase in TNF-alpha in smokers has been considered an important factor in OA induction or progression. However, studies on the effects of smoking on chondrocytes are lacking. Here we aimed to study the effects of cigarette smoke extract (CSE) associated with a TNF-alpha inhibitor on cell death of primary human chondrocytes derived from osteoarthritic patients. CSE at 10% led to cell death by apoptosis after 48 h of incubation, together with caspase 3/7 activation, decrease in mitochondrial transmembrane potential, ROS production, and improvement in syndercan-1, perlecan, and RUNX2 gene expression. All these effects promoted by CSE were reversed by TNF-alpha inhibitor. Collagen II, F-actin, and SOX9 were also analyzed, and CSE promoted alteration in the expression of these proteins. In conclusion, our results support the clinical impact of smoking on OA development by showing the detrimental action of CSE on osteoarthritis-derived chondrocytes and the protective effects of TNF-alpha inhibitors, reinforcing the importance of this cytokine in the cartilage injury process.

Aberrant Rho-associated kinase function could be associated with increased bone fragility. Since cigarette smoke (CS) exposure promotes the increase in bone fragility due to changes in bone tissue components, this study aimed to investigate how CS exposure could modulate the Rho kinase-associated bone structural changes. Mice were assigned to four groups: control; smoke; control with Rho kinase inhibitor administration; and smoke with a Rho kinase inhibitor. Bone samples were obtained to assess bone histomorphometry analysis, type I collagen composition, and MEPE expression in trabeculae. We observed that CS exposure induced decreased trabecular and osteoid thickness. A concomitant increase in the osteoclastic and erosion surfaces and a decrease in the mineralization surface were observed. Additionally, CS exposure decreased the type I collagen and MEPE expression. Rho kinase inhibitor administration recovered the bone mineralization and the collagen type I deposition. Conclusions: CS exposure increases Rho kinase activity in bone cells, leading to structural changes. The administration of a Rho GTPases inhibitor partially reverses these effects, likely due to the recovery in osteoblast activity.