Toxicological mechanisms underlying oxidant pollutant-induced airway injury

The health effect of atmospheric pollution is causing increasing public concern. Several controlled human-exposure studies have clearly. shown that oxidant pollutants, including ozone, nitrogen dioxide, and diesel exhaust, induce an acute inflammatory response in human airways. The main component of this response involves the influx of polymorphonuclear leukocytes (PMN) and is mediated via the upregulation of transcription factors NF-kappa B, AP-1, and NF-IL6; leukocyte-endothelial adhesion molecules, and chemokine secretion, including IL-8 and Gro-alpha. The results of recent studies also suggest that short-term exposure to ozone leads to neurogenic inflammation by causing damage to the bronchial epithelium and stimulating subepithelial sensory nerves to release substance P. In addition, such exposures lead to the consumption of endogenous antioxidants that are present in the airway lining fluid. Studies in asthmatics have shown that oxidant pollutants, including ozone and nitrogen dioxide, induce PMN influx in the airways and potentiate responses to inhaled aero-allergens. This article will review various studies addressing the toxicological mechanisms underlying oxidant pollutant-induced airways injury.