<scp>PDCD5</scp> Contributes to Airway Epithelial Cell Damage via Mitochondrial Pathway and Participates in <scp>COPD</scp> Pathogenesis

Airway epithelial injury plays a critical role in the pathogenesis of chronic obstructive pulmonary disease (COPD). Mitochondrial dysfunction is implicated in this injury, while the underlying mechanism remains incompletely understood. RNA sequencing was conducted to identify key genes involved in mitochondrial dysfunction in airway epithelial injury induced by cigarette smoke extract (CSE). We identified 1981 significantly up-regulated and 4952 down-regulated differentially expressed genes (DEGs) in CSE-treated airway epithelial cells. A protein-protein interaction network constructed from the DEGs revealed that several key genes were involved in CSE-induced airway epithelial injury. Additionally, PDCD5 was identified as a hub gene potentially linked to mitochondrial dysfunction. PDCD5 expression was significantly increased in the airway epithelium of COPD patients and the corresponding experimental mice. The mRNA and protein expression levels of PDCD5 were significantly increased in concentration- and time-dependent manners in airway epithelial cells treated with CSE. PDCD5 silencing significantly attenuated CSE-induced mitochondrial reactive oxygen species (ROS) accumulation, mitochondrial membrane potential loss, and intracellular ATP depletion. Transmission electron microscopy revealed that PDCD5 siRNA treatment ameliorated CSE-induced mitochondrial structural damage. Moreover, PDCD5 knockdown significantly reduced intracellular ROS accumulation, attenuated apoptosis increases, and inhibited cell viability decline in airway epithelial cells treated with CSE. Our findings demonstrate that PDCD5 contributes to airway epithelial cell damage through the mitochondrial pathway and participates in the pathogenesis of COPD, implicating it as a potential diagnostic biomarker and therapeutic target for COPD.