Beyond cytotoxicity: pollutant mixtures elicit unconventional epithelial-fibroblast signaling in a human lung air-liquid interface co-culture model

These findings indicate that early sub-lethal co-exposure to Al₂O₃ NPs and HCl can trigger fibroblast activation independently of classical cytokine induction. This unconventional paracrine response suggests a mechanistic link between early epithelial stress and fibroblast-driven remodeling, underscoring the importance of investigating non-canonical pathways in lung responses to mixed environmental pollutants.