Wheezing is common among preschool children, representing a group of highly heterogeneous conditions with varying natural history. Several phenotypes of wheezing have been proposed to facilitate the identification of young children who are at risk of subsequent development of asthma. Epidemiological and immunological studies across different populations have revealed the key role of environmental factors in influencing the progression from preschool wheezing to childhood asthma. Significant risk factors include severe respiratory infections, allergic sensitization, and exposure to tobacco smoke. In contrast, a farming/rural environment has been linked to asthma protection in both human and animal studies. Early and intense exposures to microorganisms and microbial metabolites have been demonstrated to alter host immune responses to allergens and viruses, thereby driving the trajectory away from wheezing illness and asthma. Ongoing clinical trials of candidate microbes and microbial products have shown promise in shaping the immune function to reduce episodes of viral-induced wheezing. Moreover, restoring immune training may be especially important for young children who had reduced microbial exposure due to pandemic restrictions. A comprehensive understanding of the role of modifiable environmental factors will pave the way for developing targeted prevention strategies for preschool wheezing and asthma.

中文翻译：

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从学龄前喘息到哮喘：环境决定因素

喘息在学龄前儿童中很常见，代表一组具有不同自然史的高度异质的病症。已经提出了几种喘息表型，以帮助识别有后续发展为哮喘风险的幼儿。不同人群的流行病学和免疫学研究揭示了环境因素在影响学龄前喘息到儿童哮喘进展中的关键作用。重要的危险因素包括严重呼吸道感染、过敏和接触烟草烟雾。相比之下，在人类和动物研究中，农业/农村环境与哮喘保护有关。已证明，早期和强烈接触微生物和微生物代谢物可以改变宿主对过敏原和病毒的免疫反应，从而远离喘息疾病和哮喘。正在进行的候选微生物和微生物产品的临床试验显示出在塑造免疫功能以减少病毒引起的喘息发作方面的前景。此外，恢复免疫训练对于因大流行限制而减少微生物暴露的幼儿来说可能尤其重要。全面了解可改变的环境因素的作用将为制定针对学龄前喘息和哮喘的有针对性的预防策略铺平道路。