Maziak Wasim
Syrian Center for Tobacco Studies, Aleppo, Syria.
BMC Pulm Med. 2005 Mar 31;5:5. doi: 10.1186/1471-2466-5-5.
The recent increase in childhood asthma has been a puzzling one. Recent views focus on the role of infection in the education of the immune system of young children. However, this so called hygiene hypothesis fails to answer some important questions about the current trends in asthma or to account for environmental influences that bear little relation to infection.
The multi-factorial nature of asthma, reflecting the different ways we tend to interact with our environment, mandates that we look at the asthma epidemic from a broader perspective. Seemingly modern affluent lifestyles are placing us increasingly in static, artificial, microenvironments very different from the conditions prevailed for most part of our evolution and shaped our organisms. Changes that occurred during the second half of the 20th century in industrialized nations with the spread of central heating/conditioning, building insulation, hygiene, TV/PC/games, manufactured food, indoor entertainment, cars, medical care, and sedentary lifestyles all seem to be depriving our children from the essential inputs needed to develop normal airway function (resistance). Asthma according to this view is a manifestation of our respiratory maladaptation to modern lifestyles, or in other words to our increasingly artificial habitats. The basis of the artificial habitat notion may lie in reduced exposure of innate immunity to a variety of environmental stimuli, infectious and non-infectious, leading to reduced formulation of regulatory cells/cytokines as well as inscribed regulatory pathways. This could contribute to a faulty checking mechanism of non-functional Th2 (and likely Th1) responses, resulting in asthma and other immuno-dysregulation disorders.
In this piece I discuss the artificial habitat concept, its correspondence with epidemiological data of asthma and allergy, and provide possible immunological underpinning for it from an evolutionary perspective of health and disease.
近期儿童哮喘发病率的上升令人困惑。近期观点聚焦于感染在幼儿免疫系统发育中的作用。然而，这种所谓的卫生假说未能回答有关当前哮喘趋势的一些重要问题，也无法解释与感染关系不大的环境影响因素。
哮喘的多因素性质反映了我们与环境相互作用的不同方式，这就要求我们从更广泛的角度看待哮喘流行问题。看似现代的富裕生活方式正使我们越来越多地置身于静态、人工的微环境中，这些环境与我们进化过程中大部分时间所处的条件截然不同，且塑造了我们的机体。20世纪下半叶，工业化国家随着中央供暖/空调的普及、建筑隔热、卫生条件改善、电视/电脑/游戏、加工食品、室内娱乐、汽车、医疗保健以及久坐不动的生活方式等发生的变化，似乎都在剥夺我们孩子发育正常气道功能（抵抗力）所需的基本要素。按照这种观点，哮喘是我们的呼吸系统对现代生活方式，或者换句话说对我们日益人工化的栖息地不适应的一种表现。人工栖息地概念的基础可能在于先天免疫对各种环境刺激（传染性和非传染性）的暴露减少，导致调节性细胞/细胞因子以及固有调节途径的形成减少。这可能导致对无功能的Th2（可能还有Th1）反应的检查机制出现故障，从而引发哮喘和其他免疫失调疾病。
在本文中，我讨论了人工栖息地概念、它与哮喘和过敏流行病学数据的对应关系，并从健康与疾病的进化角度为其提供了可能的免疫学依据。
