Urban Dust Nanoparticles Induce Proinflammatory Activation of Human Bronchial Epithelial Cells

Air pollution remains a major environmental challenge, largely driven by urban dust composed of suspended solid particles of diverse origins and chemical compositions. Particulate matter (PM_2.5) and ultrafine urban dust nanoparticles (NPs), with diameters smaller than 2.5 μm and 100 nm, respectively, pose a particular threat to human health. In this study, we present the first evidence that NPs induce pro-inflammatory activation of human bronchial epithelial cells. Exposure to non-cytotoxic concentrations of NPs led to a significant increase in the mRNA levels of pro-inflammatory markers IL-8, IL-1β, IL-6, and ICAM-1, accompanied by increased secretion of the cytokines IL-8 and IL-6. Heat treatment of NPs, which removed their organic components, completely abolished their ability to stimulate cytokine secretion. NP-induced upregulation of pro-inflammatory gene expression depended on both surface-adsorbed organic compounds and inorganic particle constituents.