Worldwide 300 million children and adults are affected by asthma. The development of asthma is influenced by environmental and other exogenous factors synergizing with genetic predisposition, and shaping the lung microbiome especially during birth and in very early life. The healthy lung microbial composition is characterized by a prevalence of bacteria belonging to the phyla Bacteroidetes, Actinobacteria, and Firmicutes. However, viral respiratory infections are associated with an abundance of Proteobacteria with genera Haemophilus and Moraxella in young children and adult asthmatics. This dysbiosis supports the activation of inflammatory pathways and contributes to bronchoconstriction and bronchial hyperresponsiveness. Exogenous factors can affect the natural lung microbiota composition positively (farming environment) or negatively (allergens, air pollutants). It is evident that also gut microbiota dysbiosis has a high influence on asthma pathogenesis. Antibiotics, antiulcer medications, and other drugs severely impair gut as well as lung microbiota. Resulting dysbiosis and reduced microbial diversity dysregulate the bidirectional crosstalk across the gut-lung axis, resulting in hypersensitivity and hyperreactivity to respiratory and food allergens. Efforts are undertaken to reconstitute the microbiota and immune balance by probiotics and engineered bacteria, but results from human studies do not yet support their efficacy in asthma prevention or treatment. Overall, dysbiosis of gut and lung seem to be critical causes of the increased emergence of asthma.

中文翻译：

---

肠道菌群失调和肺微生物组在哮喘中起作用。

全世界有3亿儿童和成人患有哮喘。哮喘的发展受到与遗传易感性协同作用的环境和其他外源因素的影响，尤其是在出生时和非常早的生命中，肺部微生物组的形成就受到影响。健康的肺部微生物组成的特征是普遍属于细菌纲门菌，放线菌和硬菌的细菌。但是，病毒性呼吸道感染与嗜血杆菌属和莫拉氏菌属大量的变形杆菌有关。在幼儿和成人哮喘患者中使用。这种营养不良支持炎性途径的激活，并有助于支气管收缩和支气管高反应性。外源因素可以对自然肺微生物群组成产生积极的影响（农业环境）或负面影响（过敏原，空气污染物）。显然，肠道菌群失调也对哮喘的发病机理有很大影响。抗生素，抗溃疡药物和其他药物会严重损害肠道以及肺微生物。导致的营养不良和微生物多样性降低，会扰乱整个肠肺轴的双向串扰，导致对呼吸道和食物过敏原的过敏和反应过度。致力于通过益生菌和工程菌重建微生物群和免疫平衡，但是人体研究的结果尚不能支持其在哮喘预防或治疗中的功效。总体而言，肠道和肺部营养不良似乎是哮喘发作增加的关键原因。