Eder Waltraud, von Mutius Erika
Arizona Respiratory Center, University of Arizona, Tucson 85724, USA.
Curr Opin Allergy Clin Immunol. 2004 Apr;4(2):113-7. doi: 10.1097/00130832-200404000-00008.
The hygiene hypothesis has gained strong support over the past few years. Exposure to microbial products in early life could be an underlying factor in this hypothesis, but the mechanisms that lead from a less clean and more crowded environment to a lower prevalence of asthma and allergies are not known. Among the variety of potential microbial molecules that may confer protection against the development of asthma and allergies, endotoxin, a component of Gram-negative bacteria, has incited lively as well as controversial discussions. This review focuses on recent studies on endotoxin and its role in the context of the hygiene hypothesis.
Results from cross-sectional surveys, prospective cohorts, and experimental studies in vitro and in rodents suggest that exposure to house dust endotoxin in early life protects from atopic sensitization and IgE-mediated diseases, but is a risk factor for wheezing in infancy.
Numerous studies have supported the hygiene hypothesis, but whether endotoxin by itself confers the protection or whether it acts as a marker for another environmental exposure is still unclear. The challenge for the future will be to identify those factors that confer the protection proposed by the hygiene hypothesis, and to find strategies to modify the environment without causing harm to susceptible individuals.
在过去几年中，卫生假说获得了有力支持。早年接触微生物产物可能是该假说的一个潜在因素，但从较不清洁且更拥挤的环境导致哮喘和过敏症患病率降低的机制尚不清楚。在各种可能赋予针对哮喘和过敏症发展的保护作用的潜在微生物分子中，革兰氏阴性菌的一种成分内毒素引发了热烈且有争议的讨论。本综述重点关注内毒素及其在卫生假说背景下作用的近期研究。
横断面调查、前瞻性队列研究以及体外和啮齿动物实验研究的结果表明，早年接触室内灰尘内毒素可预防特应性致敏和IgE介导的疾病，但却是婴儿期喘息的一个危险因素。
众多研究支持了卫生假说，但内毒素本身是否具有保护作用，或者它是否作为另一种环境暴露的标志物仍不清楚。未来的挑战将是确定那些赋予卫生假说所提出的保护作用的因素，并找到在不伤害易感个体的情况下改变环境的策略。
