Microbial dysbiosis is a potential mediator of air pollution-induced adverse outcomes. However, a systemic comparison of the lung and gut microbiome alterations and lung-gut axis following air pollution exposure is scant. In this study, we exposed male C57BL/6J mice to inhaled air, CB (10 mg/m3), O3 (2 ppm) or CB + O3 mixture for 3 h/day for either one day or four consecutive days and were euthanized 24 h post last exposure. The lung and gut microbiome were quantified by 16 s sequencing. Multiple CB + O3 exposures induced an increase in the lung inflammatory cells (neutrophils, eosinophils and B lymphocytes), reduced absolute bacterial load in the lungs and increased load in the gut. CB + O3 exposure was more potent as it decreased lung microbiome alpha diversity just after a single exposure. CB + O3 co-exposure uniquely increased Clostridiaceae and Prevotellaceae in the lungs. Serum short chain fatty acids (SCFA) (acetate and propionate) were increased significantly only after CB + O3 co-exposure. A significant increase in SCFA producing bacterial families (Ruminococcaceae, Lachnospiraceae, and Eubacterium) were also observed in the gut after multiple exposures. Co-exposure induced significant alterations in the gut derived metabolite receptors/mediator (Gcg, Glp-1r, Cck) mRNA expression. Oxidative stress related mRNA expression in lungs, and oxidant levels in the BALF, serum and gut significantly increased after CB + O3 exposures. Our study confirms distinct gut and lung microbiome alterations after CB + O3 inhalation co-exposure and indicate a potential homeostatic shift in the gut microbiome to counter deleterious impacts of environmental exposures on metabolic system.

中文翻译：

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共暴露于超细炭黑和臭氧后微生物组改变的肺肠轴

微生物失调是空气污染引起的不良后果的潜在中介。然而，对空气污染暴露后肺和肠道微生物组改变以及肺-肠轴的系统比较很少。在这项研究中，我们将雄性 C57BL/6J 小鼠暴露于吸入空气、CB (10 mg/m3)、O3 (2 ppm) 或 CB + O3 混合物中，每天 3 小时，持续一天或连续四天，然后被安乐死 24 h 最后一次曝光后。通过 16 秒测序对肺和肠道微生物组进行量化。多次 CB + O3 暴露会导致肺部炎症细胞（中性粒细胞、嗜酸性粒细胞和 B 淋巴细胞）增加，肺部绝对细菌负荷减少，肠道负荷增加。CB + O3 暴露更有效，因为它会在单次暴露后降低肺微生物组 α 多样性。CB + O3 共同暴露独特地增加了肺中的梭菌科和普雷沃氏菌科。血清短链脂肪酸 (SCFA)（醋酸盐和丙酸盐）仅在 CB + O3 共同暴露后显着增加。多次暴露后，肠道中产生 SCFA 的细菌科（瘤胃球菌科、毛螺菌科和真杆菌科）也显着增加。共同暴露诱导肠道衍生代谢物受体/介质（Gcg、Glp-1r、Cck）mRNA 表达的显着改变。CB + O3 暴露后，肺中氧化应激相关的 mRNA 表达以及 BALF、血清和肠道中的氧化剂水平显着增加。