Abstract Introduction People living with HIV (PLWH) experience a higher incidence of chronic lung diseases such as COPD and emphysema, which are further exacerbated by cigarette smoking. Despite viral suppression, persistent inflammation and premature lung aging remain common in PLWH. Cigarette smoking, highly prevalent in this population, further aggravates oxidative stress, mitochondrial dysfunction, and epithelial damage. Mitochondria are central to cellular energy and redox homeostasis, and their quality control is maintained through mitophagy - an autophagic process that selectively removes damaged mitochondria. Receptor-mediated mitophagy, primarily regulated by BNIP3L (NIX) and FUNDC1, is critical for maintaining mitochondrial integrity under stress conditions. Dysregulation of these pathways can lead to excessive reactive oxygen species (ROS) accumulation, epithelial injury, inflammation, and tissue remodeling. This study investigates how HIV and cigarette smoke together alter receptor-mediated mitophagy in the lung epithelium. Methodology Lung tissue samples were obtained from healthy donors (n = 4), smokers (n = 4), HIV-infected non-smokers (n = 4), and HIV-infected smokers (n = 3). In parallel, primary normal human bronchial epithelial (NHBE) cells were differentiated at an air-liquid interface and exposed to whole cigarette smoke using a SCIREQ® in vitro smoking robot to achieve physiologically relevant exposures. Chronic smoke exposure was performed every three days for 24-hour intervals, followed by infection with an R5-tropic HIV-1 strain. Expression of mitophagy-related genes (BNIP3L and FUNDC1) was analyzed by qRT-PCR and Western blotting. Secreted inflammatory cytokines were quantified by ELISA. Result Distinct alterations in mitophagy-associated gene expression were observed. BNIP3L expression increased in smoker lungs relative to healthy controls, suggesting an adaptive mitophagy response to oxidative stress, likely mediated through HIF1A activation. In contrast, HIV-infected lungs exhibited marked suppression of BNIP3L, and HIV-infected smokers showed further reduction, indicating that HIV interferes with smoke-induced mitophagy activation. FUNDC1 expression was consistently downregulated in all groups, suggesting impairment of basal mitophagy capacity. These findings indicate that lung tissue attempts to clear damaged mitochondria via HIF1A-driven mitophagy, but HIV blunts this protective mechanism. Conclusion Our findings suggest that HIV infection and cigarette smoke differentially modulate receptor-mediated mitophagy in the lung epithelium. While cigarette smoke induces BNIP3L as an adaptive response, HIV suppresses both BNIP3L and FUNDC1, impairing mitochondrial clearance and promoting oxidative stress and inflammation. The combined exposure amplifies mitochondrial dysfunction, contributing to chronic epithelial injury. Dysregulated mitophagy may thus represent a critical mechanism linking HIV, smoking, and COPD pathogenesis. This abstract is funded by: R01 158316; 167655; 147715, and R01176254.
Khasa et al. (Fri,) studied this question.