title: Mechanistic impact of outdoor air pollution on asthma and allergic diseases.
abstract: Over the past decades, asthma and allergic diseases, such as allergic rhinitis and eczema, have become increasingly common, but the reason for this increased prevalence is still unclear. It has become apparent that genetic variation alone is not sufficient to account for the observed changes; rather, the changing environment, together with alterations in lifestyle and eating habits, are likely to have driven the increase in prevalence, and in some cases, severity of disease. This is particularly highlighted by recent awareness of, and concern about, the exposure to ubiquitous environmental pollutants, including chemicals with oxidant-generating capacities, and their impact on the human respiratory and immune systems. Indeed, several epidemiological studies have identified a variety of risk factors, including ambient pollutant gases and airborne particles, for the prevalence and the exacerbation of allergic diseases. However, the responsible pollutants remain unclear and the causal relationship has not been established. Recent studies of cellular and animal models have suggested several plausible mechanisms, with the most consistent observation being the direct effects of particle components on the generation of reactive oxygen species (ROS) and the resultant oxidative stress and inflammatory responses. This review attempts to highlight the experimental findings, with particular emphasis on several major mechanistic events initiated by exposure to particulate matters (PMs) in the exposure-disease relationship.
authors.affiliation: 1 Division of Environmental Health and Occupational Medicine, National Health Research Institutes, 115 Zhunan, Taiwan ; 2 Division of Allergy and Clinical Immunology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA ; 3 State Key Laboratory of Respiratory Diseases, The First Affiliated Hospital, Guangzhou Medical University, Guangzhou 510120, China ; 4 National Heart & Lung Institute, Imperial College London & Respiratory Biomedical Research Unit, Royal Brompton & Harefield NHS Trust, London, UK.
authors.forename: Shau-Ku
authors.initials: SK
authors.lastname: Huang
authors.affiliation: 1 Division of Environmental Health and Occupational Medicine, National Health Research Institutes, 115 Zhunan, Taiwan ; 2 Division of Allergy and Clinical Immunology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA ; 3 State Key Laboratory of Respiratory Diseases, The First Affiliated Hospital, Guangzhou Medical University, Guangzhou 510120, China ; 4 National Heart & Lung Institute, Imperial College London & Respiratory Biomedical Research Unit, Royal Brompton & Harefield NHS Trust, London, UK.
authors.forename: Qingling
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: 1 Division of Environmental Health and Occupational Medicine, National Health Research Institutes, 115 Zhunan, Taiwan ; 2 Division of Allergy and Clinical Immunology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA ; 3 State Key Laboratory of Respiratory Diseases, The First Affiliated Hospital, Guangzhou Medical University, Guangzhou 510120, China ; 4 National Heart & Lung Institute, Imperial College London & Respiratory Biomedical Research Unit, Royal Brompton & Harefield NHS Trust, London, UK.
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Qiu
authors.affiliation: 1 Division of Environmental Health and Occupational Medicine, National Health Research Institutes, 115 Zhunan, Taiwan ; 2 Division of Allergy and Clinical Immunology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA ; 3 State Key Laboratory of Respiratory Diseases, The First Affiliated Hospital, Guangzhou Medical University, Guangzhou 510120, China ; 4 National Heart & Lung Institute, Imperial College London & Respiratory Biomedical Research Unit, Royal Brompton & Harefield NHS Trust, London, UK.
authors.forename: Kian Fan
authors.initials: KF
authors.lastname: Chung
keywords: Air pollution; allergic disease; aryl hydrocarbon receptor (AhR); asthma; particulate matter (PM); polycyclic aromatic hydrocarbon (PAH); transition metal