Dimethyl phthalate induces cytotoxicity, oxidative stress, pro-inflammatory cytokine expression and fibronectin...

Dimethyl Phthalate (DMP) is a phthalate ester, widely present in nail polishes, hairsprays, coatings, textiles, and certain insect repellents, contributing to its pervasive environmental and occupational presence. DMPs are now considered priority emerging contaminants due to limited regulation and potential long-term adverse effects on human health. Despite inhalation being a major route of exposure, data on the pulmonary toxicity of phthalates, particularly DMP, remain limited.

To investigate the cellular responses associated with DMP-induced pulmonary toxicity using the human lung adenocarcinoma-derived alveolar epithelial cell line A549 as an in vitro model.

A549 cells were exposed to varying concentrations of DMP for different durations to investigate its cytotoxic effects. Cell morphology, viability, oxidative stress, mitochondrial superoxide generation and apoptosis were evaluated using phase-contrast microscopy, MTT assay, DCFH-DA, MitoSOX staining, and Annexin V/PI flow cytometry. Inflammatory and fibrotic responses were assessed by measuring cytokine and fibronectin expression using RT-qPCR, ELISA and ICC.

Exposure to DMP resulted in significant concentration- and time-dependent cytotoxicity, accompanied by elevated intracellular and mitochondrial reactive oxygen species generation. DMP treatment also induced necrotic cell death and significantly increased the mRNA expression of the pro-inflammatory cytokines TNF-α, IL-6, IL-8, and enhanced the secretion of IL-6 and IL-8. Furthermore, DMP exposure enhanced fibronectin expression and accumulation, suggesting activation of remodeling-associated responses.

These findings demonstrate that DMP elicits oxidative stress-driven epithelial damage, inflammatory responses, and fibronectin accumulation in human lung epithelial cells that overlap with pathways implicated in chronic respiratory diseases, including COPD.