Copper-dependent inflammation and nuclear factor-κB activation by particulate air pollution

Particulate air pollution causes increased cardiopulmonary morbidity and mortality, but the chemical determinants responsible for its biologic effects are not understood. We studied the effect of total suspended particulates collected in Prove, Utah, an area when an increase in respiratory symptoms in relation to levels of particulate pollution has been well documented. Prove particulates caused cytokine-induced neutrophil chemoattractant-dependent inflammation of rat lungs. Prove particulates stimulated interleukin-6 (IL-6) and IL-8 production, increased IL-8 messenger RNA (mRNA) and enhanced expression of intercellular adhesion molecule-1 (ICAM-1) in cultured BEAS-2B cells, and stimulated IL-8 secretion in primary cultures of human bronchial epithelium. Cytokine secretion was preceded by activation of the transcription factor nuclear factor-kappa B (NF-kappa B) and was reduced by treatment of cultures with superoxide dismutase, deferoxamine, or N-acetylcysteine. These biologic effects were replicated by culturing BEAS cells with quantities of Cu2+ found in Prove extract. IL-8 secretion by BEAS cells could be modified by addition of normal constituents of airway lining fluid to the culture medium. Mucin significantly reduced IL-8 secretion, and ceruloplasmin significantly increased IL-8 secretion and activation of NF-kappa B. These findings suggest that copper ions may cause some of the biologic effects of inhaled particulate air pollution in the Prove region of the United States, and may provide an explanation for the sensitivity of asthmatic individuals to Prove particulates that has been observed in epidemiologic studies.