Hospital Clinic, IDIBAPS, Universitat de Barcelona, Barcelona, Spain.
CIBER de Enfermedades Respiratorias - CIBERES, Madrid, Spain.
Eur Respir J. 2017 Apr 12;49(4). doi: 10.1183/13993003.02086-2016. Print 2017 Apr.
The healthy lung has previously been considered to be a sterile organ because standard microbiological culture techniques consistently yield negative results. However, culture-independent techniques report that large numbers of microorganisms coexist in the lung. There are many unknown aspects in the field, but available reports show that the lower respiratory tract microbiota: 1) is similar in healthy subjects to the oropharyngeal microbiota and dominated by members of the Firmicutes, Bacteroidetes and Proteobacteria phyla; 2) shows changes in smokers and well-defined differences in chronic respiratory diseases, although the temporal and spatial kinetics of these changes are only partially known; and 3) shows relatively abundant non-cultivable bacteria in chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, cystic fibrosis and bronchiectasis, with specific patterns for each disease. In all of these diseases, a loss of diversity, paralleled by an over-representation of Proteobacteria (dysbiosis), has been related to disease severity and exacerbations. However, it is unknown whether dysbiosis is a cause or a consequence of the damage to bronchoalveolar surfaces.Finally, little is known about bacterial functionality and the interactions between viruses, fungi and bacteria. It is expected that future research in bacterial gene expressions, metagenomics longitudinal analysis and host-microbiome animal models will help to move towards targeted microbiome interventions in respiratory diseases.
健康的肺以前被认为是一个无菌的器官，因为标准的微生物培养技术总是产生阴性结果。然而，非培养技术报告说，大量的微生物共存于肺部。该领域有许多未知的方面，但现有报道表明，下呼吸道微生物群：1）在健康受试者中与口咽微生物群相似，以厚壁菌门、拟杆菌门和变形菌门的成员为主；2）在吸烟者中发生变化，在慢性呼吸道疾病中存在明确的差异，尽管这些变化的时空动力学仅部分为人所知；3）在慢性阻塞性肺疾病、特发性肺纤维化、囊性纤维化和支气管扩张症中显示出相对丰富的不可培养细菌，每种疾病都有特定的模式。在所有这些疾病中，多样性的丧失，伴随着变形菌门（失调）的过度表达，与疾病的严重程度和恶化有关。然而，尚不清楚失调是气道肺泡表面损伤的原因还是结果。最后，关于细菌功能以及病毒、真菌和细菌之间的相互作用知之甚少。预计未来在细菌基因表达、宏基因组纵向分析和宿主-微生物组动物模型方面的研究将有助于针对呼吸道疾病的微生物组干预措施。
