074 | Role of macrophage gasdermins in cigarette smoke-associated mitochondrial dysfunction

Chiara Finocchio^1|2, Maria Concetta Volpe¹, Maria Rita Giuffrè¹, Francesca Rappa^2|4, Alessandro Bertani³, Chiara Cipollina¹ | ¹Fondazione RiMED, Palermo, Italy; ²Dipartimento di Biomedicina, Neuroscienze e Diagnostica Avanzata, Università di Palermo, Italy; ³IRCCS ISMETT-UPMC, Palermo, Italy; ⁴Istituto di Farmacologia Traslazionale IFT-CNR, Palermo, Italy.

Chronic obstructive pulmonary disease (COPD) is a major cause of worldwide mortality, characterized by chronic inflammation and alveolar tissue destruction, with cigarette smoking (CS) being a primary risk factor. Resident macrophages are the dominant immune cell type in the lung. CS exposure impairs macrophage functions, inducing mitochondrial damage and imbalanced immune responses, all thought to contribute to COPD pathogenesis. Macrophages express high levels of gasdermins (GSDMs), a family of pore-forming proteins involved in innate immune responses. GSDMs, activated by inflammatory caspases, produce membrane targeting N-terminal (NT) fragments. Emerging evidence suggests that both GSDME-NT and GSDMD-NT can localize to mitochondria(1). We have previously shown that CS causes activation of GSDMD and GSDME in human primary macrophages and increases GSDMD-NT expression in alveolar macrophages from smokers(2). However, whether GSDMs contribute to mitochondrial dysfunction in cigarette smoke–induced inflammation and COPD has been never explored. We hypothesized that GSDMD and GSDME mediate CS-induced mitochondrial dysfunction, amplifying inflammatory signaling in the lung. We found that cigarette smoke exposure promotes caspase-dependent activation and mitochondrial localization of GSDME and GSDMD in human macrophages (mitochondrial fractionation and confocal microscopy). This is associated with cytochrome-c release, altered mitochondrial morphology, and increased mitochondrial reactive oxygen species production. Importantly, preliminary data show increased levels of cleaved GSDME in alveolar macrophages from smokers and COPD patients compared to non-smoking controls. These findings suggest that gasdermin–mitochondria axis may represent a previously unrecognized mechanism contributing to dysregulated immunity in COPD.