Genotoxic and cytokine-associated responses to benzo[g,h,i]perylene and benzo[b]fluoranthene in a human lung co-culture model at the pseudo-air-liquid interface.

Polycyclic aromatic hydrocarbons (PAHs), including benzo[g,h,i]perylene (BGP) and benzo[b]fluoranthene (BBF), are ubiquitous airborne pollutants with significant toxicological relevance. Inhalation represents the primary exposure route, with the respiratory epithelium and alveolar macrophages serving as key targets for adverse effects. Despite their prevalence, mechanistic data on BGP and BBF, particularly in respiratory cell models, remain limited. Here, we evaluated the cytotoxic, genotoxic, and cytokine-associated effects of BGP and BBF in a co-culture of human alveolar epithelial (A549) and macrophage-like differentiated (dTHP-1) cells maintained at a pseudo-air-liquid interface (pseudo-ALI). No detectable genotoxic effects were observed following 24h exposure to non‑cytotoxic concentrations of BGP (≤ 18.1µM) and BBF (≤ 39.6µM), as evidenced by the absence of DNA double‑strand breaks, phospho‑histone H3 activation, and micronucleus formation. In contrast, both compounds modulated several inflammatory cytokine-associated endpoints, with BGP producing a stronger effect than BBF. BGP significantly increased IL-8 secretion and the proportion of cells expressing TNF-α, IL-6, and IL-1β, while BBF moderately elevated the proportion of cells expressing TNF-α, IL-6, and IFN-γ. Targeted qPCR analysis detected changes in selected cytokine-associated genes. These findings indicate that BGP, and to a lesser extent BBF, modulated selected inflammatory cytokines without detectable DNA damage under the tested conditions. Limited metabolic activation may have contributed to the negative genotoxicity findings; however, metabolic activity and PAH metabolite formation were not assessed in this co-culture. The results highlight inflammatory cytokine-associated effects, particularly following BGP exposure, and demonstrate the value of the A549/dTHP-1 co-culture for investigating early cellular responses to PAHs.