BACKGROUND Poor air quality is increasingly associated with several gastrointestinal diseases suggesting a possible association between air quality and the human gut microbiome. However, details on this remain largely unexplored as current available research is scarce. The aim of this comprehensive rigorous review was to summarize the existing reports on the impact of indoor or outdoor airborne pollutants on the animal and human gut microbiome and to outline the challenges and suggestions to expand this field of research. METHODS AND RESULTS A comprehensive search of several databases (inception to August 9, 2019, humans and animals, English language only) was designed and conducted by an experienced librarian to identify studies describing the impact of air pollution on the human gut microbiome. The retrieved articles were assessed independently by two reviewers. This process yielded six original research papers on the animal GI gastrointestinal microbiome and four on the human gut microbiome. β-diversity analyses from selected animal studies demonstrated a significantly different composition of the gut microbiota between control and exposed groups but changes in α-diversity were less uniform. No consistent findings in α or β-diversity were reported among the human studies. Changes in microbiota at the phylum level disclosed substantial discrepancies across animal and human studies. CONCLUSIONS A different composition of the gut microbiome, particularly in animal models, is associated with exposure to air pollution. Air pollution is associated with various taxa changes, which however do not follow a clear pattern. Future research using standardized methods are critical to replicate these initial findings and advance this emerging field.

中文翻译：

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空气质量对胃肠道微生物组的影响：综述。

背景技术不良的空气质量越来越多地与几种胃肠道疾病相关，这表明空气质量与人类肠道微生物组之间可能存在关联。但是，由于目前缺乏可用的研究，因此在很大程度上尚待探索。这项全面严格审查的目的是总结有关室内或室外空气污染物对动物和人类肠道微生物组的影响的现有报告，并概述扩大该研究领域的挑战和建议。方法和结果由经验丰富的图书馆员设计和实施了对多个数据库的综合搜索（从开始到2019年8月9日，人类和动物，仅英语），以识别描述空气污染对人体肠道微生物组的影响的研究。检索到的文章由两名审阅者独立评估。这一过程产生了关于动物胃肠胃肠微生物组的六篇原始研究论文，以及关于人类肠道微生物组的四篇论文。所选动物研究的β多样性分析表明，对照组和暴露组之间肠道菌群的组成存在显着差异，但α多样性的变化不太均匀。在人类研究中，没有报告关于α或β多样性的一致发现。在动物水平上微生物群的变化揭示了动物和人类研究之间的重大差异。结论肠道微生物组的不同组成，尤其是在动物模型中，与空气污染有关。空气污染与各种分类单元变化相关，但是变化趋势不明显。