Nuclear and cytoskeletal structural alterations in human alveolar epithelial cells by solvent-extracted organic matter from PM2.5.

Particulate matter (PM2.5) contains a complex mixture of compounds with diverse physicochemical and toxicological properties. Although, solvent-extractable organic compounds of PM2.5 are known to induce oxidative and metabolic alterations, their impact on cellular structural integrity remains insufficiently characterized. In this study, we evaluated the impact of the PM2.5 extract obtained with dichloromethane (SEOM-PM2.5) on human alveolar epithelial cells (A549). Cells were exposed to non-cytotoxic concentrations of SEOM-PM2.5 and assessed for cytoskeletal organization, nuclear morphology, cell-cycle distribution, DNA damage, caspase-3 activation, and cell death. Exposure to SEOM-PM2.5 induced marked cytoskeletal alterations, including microtubule disorganization, reduced α-tubulin expression, and actin stress-fiber formation. SEOM-PM2.5 also caused nuclear deformation, G2/M cell-cycle arrest, γH2AX-associated DNA damage, and increased apoptotic and necrotic cell populations. Our results demonstrate that SEOM-PM2.5 disrupts cytoskeletal and nuclear integrity in alveolar epithelial cells, providing mechanistic evidence that components of PM2.5 extract can compromise epithelial structural stability and promote genotoxic and apoptotic responses.