|
The pathogenesis of atopic dermatitis (AD) is attributed to both genetic and environmental factors. With regard to a genetic basis, the genes encoding filaggrin (FLG) has been most consistently replicated in more than 20 different studies. The loss-of-function mutation in FLG gene has been frequently reported in European populations, and the other responsible genes remain to be elucidated. Recent increase in the prevalence of AD suggests that the environmental factors are likely to be more important in the development of AD, because there is no evidence of abrupt genetic alterations. In terms of environmental factors, contact with endotoxin in utero or during the first year of life, i.e. hygiene hypothesis, has a protective effect on the development of asthma, hay fever and allergic sensitization, although this effect is not evident in AD. In contrast, altered distribution in gut flora during infancy seems to influence the development of AD. Moreover, recent evidences suggest that air pollution might cause AD in a susceptible individual. For example, the exposure to a variety of indoor and outdoor air pollutants such as environmental tobacco smoke, volatile organic compounds, nitrogen dioxide, and particulate matter has been reported to develop AD. It appears to be mediated by oxidative stress, which induces skin barrier dysfunction or immune dysregulation. Further investigations to examine the role of air pollution in the development of AD are needed to establish better strategy for primary prevention of AD.
|