Caspase inhibition restores collagen Iα1 and fibronectin release in cigarette smoke extract-exposed human lung fibroblasts.

Chronic obstructive pulmonary disease (COPD) is a progressive lung disease characterized by obstructed airflow, airway remodeling, and inflammation, with cigarette smoke (CS) exposure being the main risk factor. Although CS extract (CSE) has been shown to activate caspases in various cell types, the role of caspases in human lung fibroblasts (hLFs) in COPD remains poorly understood. Recent studies have linked caspases to extracellular matrix (ECM) remodeling in skin and kidney fibrosis. Caspase activation can be triggered by oxidative stress, with active caspase-3 executing the pore-forming protein gasdermin E (GSDME) in the cleaved N-terminal form GSDME-NT. We investigated whether CSE activates caspases and GSDME in hLFs and their role in ECM remodeling. MRC-5 lung fibroblasts were treated with CSE with or without the antioxidant -acetyl-cysteine (NAC) and the caspase-8 inhibitor z-IETD-fmk. We measured the effects on caspase-1-8-3/7 activation, GSDME cleavage, ECM remodeling (procollagen Iα1, COLIα1, and fibronectin, FN), and mitochondrial superoxide (mSOX) generation. Key findings were validated in patient-derived hLFs (phLFs). Our results showed that CSE induced caspase-1-8-3/7 activation, mSOX generation, and decreased COLIα1 and FN levels in MRC-5. CSE caused caspase-8-dependent activation of caspase-3, leading to GSDME cleavage. Treatment with NAC inhibited mSOX and caspase activation. Inhibition of caspase-8 and mSOX restored FN and COLIα1 levels. In phLFs, we confirmed caspase-1 and -8 activation, mSOX increase, COLIα1/FN decrease, and the effects of NAC. Our findings highlight the role of the axis caspase-8-3/7-GSDME and mSOX in regulating ECM protein, suggesting that these pathways may contribute to remodeling in COPD. This research investigates the connection between caspases, gasdermins, and extracellular matrix (ECM) remodeling in the context of cigarette smoke-associated lung diseases. The study found that cigarette smoke extract (CSE) activates caspases and gasdermin E in human lung fibroblasts, leading to decreased ECM protein expression and release. Findings herein reported suggest that targeting the caspase-8-3/7-gasdermin axis and mitochondrial reactive oxygen species may help restore ECM remodeling in chronic lung diseases associated with cigarette smoke exposure.