Airway antioxidant and inflammatory responses to diesel exhaust exposure in healthy humans

Abstract

Pulmonary cells exposed to diesel exhaust (DE) particles in vitro respond in a hierarchical fashion with protective antioxidant responses predominating at low doses and inflammation and injury only occurring at higher concentrations. In the present study, the authors examined whether similar responses occurred in vivo, specifically whether antioxidants were upregulated following a low-dose DE challenge and investigated how these responses related to the development of airway inflammation at different levels of the respiratory tract where particle dose varies markedly.A total of 15 volunteers were exposed to DE (100 mg?m -3 airborne particulate matter with a diameter of ,10 mm for 2 h) and air in a double-blinded, randomised fashion. At 18 h postexposure, bronchoscopy was performed with lavage and mucosal biopsies taken to assess airway redox and inflammatory status. Following DE exposure, the current authors observed an increase in bronchial mucosa neutrophil and mast cell numbers, as well as increased neutrophil numbers, interleukin-8 and myeloperoxidase concentrations in bronchial lavage. No inflammatory responses were seen in the alveolar compartment, but both reduced glutathione and urate concentrations were increased following diesel exposure.In conclusion, the lung inflammatory response to diesel exhaust is compartmentalised, related to differing antioxidant responses in the conducting airway and alveolar regions.

Acute effects on pulmonary function in young healthy adults exposed to traffic-related air pollution in semi-closed transport hub in Beijing

“…Most studies generally did not found effects on lung function parameters in relation to short-term air pollution chamber exposure [9][10][11][12][13][14]. Compared with the chamber studies, our study explored the pulmonary effects in the natural environment, where more complex traffic-related air pollutants existed, this may lead to the discrepancies between the findings of the chamber studies and our own.…”

“…Acute respiratory effects of exposure to diesel exhaust have also been studied in controlled chamber studies [9][10][11][12][13][14][15]. Most studies generally did not found effects on lung function parameters in relation to short-term air pollution chamber exposure [9][10][11][12][13][14].…”

“…Acute effects on pulmonary function of exposure to traffic exhaust have been studied in controlled chamber studies [9][10][11][12][13][14][15]. However, considering the realworld exposure where mixtures of pollutants are more complex, the results of chamber studies may have some difficulties when applied to the exposure in real-world traffic micro-environment.…”

Air pollution, oxidative stress and dietary supplementation: a review

“…Similarly, low-dose diesel exposure challenge in healthy volunteers was followed by an increase of inflammatory markers in bronchial lavage. No inflammatory response was seen in the alveolar compartment, but both reduced glutathione and urate concentrations were increased following diesel exposure suggesting differential antioxidant responses in the conducting airway and alveolar regions [50].…”

“…ROS formed at the epithelial level after DEP exposure upregulate IL-10, promoting antigen-presenting cells and allergy to pollen [15]. However, controlled exposure to DEP in human subjects has been shown to respond with an increase in low molecular antioxidants in the alveolar compartment [50]. The role of oxidative stress in response to DEPs and other particles is further supported by in vitro studies in which ROS are generated by macrophages, neutrophils, eosiniphils and epithelial cells after stimulation by DEPs or particles [15].…”