Patients with asthma have an altered airway microbiota, with specific bacteria associated with severe asthma and the eosinophilic inflammatory phenotype.

Background Dysbiosis of the gut microbiome is involved in the pathogenesis of various diseases, but the contribution of gut microbes to the progression of chronic obstructive pulmonary disease (COPD) is still poorly understood. Methods We carried out 16S rRNA gene sequencing and short-chain fatty acid analyses in stool samples from a cohort of 73 healthy controls, 67 patients with COPD of GOLD stages I and II severity, and 32 patients with COPD of GOLD stages III and IV severity. Fecal microbiota from the three groups were then inoculated into recipient mice for a total of 14 times in 28 days to induce pulmonary changes. Furthermore, fecal microbiota from the three groups were inoculated into mice exposed to smoke from biomass fuel to induce COPD-like changes. Results We observed that the gut microbiome of COPD patients varied from that of healthy controls and was characterized by a distinct overall microbial diversity and composition, a Prevotella-dominated gut enterotype and lower levels of short-chain fatty acids. After 28 days of fecal transplantation from COPD patients, recipient mice exhibited elevated lung inflammation. Moreover, when mice were under both fecal transplantation and biomass fuel smoke exposure for a total of 20 weeks, accelerated declines in lung function, severe emphysematous changes, airway remodeling and mucus hypersecretion were observed. Conclusion These data demonstrate that altered gut microbiota in COPD patients is associated with disease progression in mice model.

BackgroundAmbient particulate matter exposure has been shown to increase the risks of respiratory diseases. However, the role of the lung microbiome and the immune response to inhaled particulate matter are largely unexplored. We studied the influence of biomass fuel and motor vehicle exhaust particles on the lung microbiome and pulmonary immunologic homeostasis in rats.MethodsFifty-seven Sprague–Dawley rats were randomly divided into clean air (CON), biomass fuel (BMF), and motor vehicle exhaust (MVE) groups. After a 4-week exposure, the microbial composition of the lung was assessed by 16S rRNA pyrosequencing, the structure of the lung tissue was assessed with histological analysis, the phagocytic response of alveolar macrophages to bacteria was determined by flow cytometry, and immunoglobulin concentrations were measured with commercial ELISA kits.ResultsThere was no significant difference in lung morphology between the groups. However, the BMF and MVE groups displayed greater bacterial abundance and diversity. Proteobacteria were present in higher proportions in the MVE group, and 12 bacterial families differed in their relative abundances between the three groups. In addition, particulate matter exposure significantly increased the capacity of alveolar macrophages to phagocytose bacteria and induced changes in immunoglobulin levels.ConclusionWe demonstrated that particulate matter exposure can alter the microbial composition and change the pulmonary immunologic homeostasis in the rat lung.

Objective Guidelines from different areas on the use of non-invasive ventilation in COVID-19 have generally been inconsistent. The goals were to appraise the quality and availability of guidelines stated and whether non-invasive ventilation in the early stage of the pandemic is of importance. Design and Method Databases including PubMed, Web of Science, Cochrane Library, and websites of international organizations and gray databases were searched up to June 23, 2020. We also hand-searched the reference lists of eligible papers. Results A total of 26 guidelines met the inclusion criteria. Regarding the appraisal by the Appraisal of Guidelines for Research and Evaluation (AGREE) II instrument, the guidelines’ methodological quality was low. Among six domains, Rigour. of Development and Editorial Independence were of the lowest quality. Given the lack of evidence from randomized clinical trials and the great differences between different regions, non-invasive ventilation’s recommendations generated a considerable debate at the early stage of COVID-19. Conclusions Improving the methodological quality of the guidelines should be a goal in future pandemics. Additionally, more well-designed randomized clinical trials are needed to solve the controversy on the impact of non-invasive ventilation.

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Background The role of the microbiota in the pathogenesis of chronic obstructive pulmonary disease (COPD) following exposure to ambient particulate matter (PM) is largely unknown. Methods Fifty-four male Sprague-Dawley rats were exposed to clean air, biomass fuel (BMF), or motor vehicle exhaust (MVE) for 4, 12, and 24 weeks. We performed pulmonary inflammation evaluation, morphometric measurements, and lung function analysis in rat lung at three different times points during exposure. Lung and gut microbial composition was assessed by 16S rRNA pyrosequencing. Serum lipopolysaccharide levels were measured and short-chain fatty acids in colon contents were quantified. Results After a 24-week PM exposure, rats exhibited pulmonary inflammation and pathological changes characteristic of COPD. The control and PM exposure (BMF and MVE) groups showed similar microbial diversity and composition in rat lung. However, the gut microbiota after 24 weeks PM exposure was characterized by decreased microbial richness and diversity, distinct overall microbial composition, lower levels of short-chain fatty acids, and higher serum lipopolysaccharide. Conclusion Chronic exposure to ambient particulate matter induces gut microbial dysbiosis and metabolite shifts in a rat model of chronic obstructive pulmonary disease.

Background Little is known about the quality and potential impacts of the guidelines for COVID-19 management. Methods We systematically searched PubMed, Web of Science, Cochrane Library, guideline databases and specialty society Web sites to evaluate the quality of the retrieved guidelines using the Appraisal of Guidelines for Research and Evaluation II. Results A total of 66 guidelines were identified. Only 24% were categorized as “recommended” for clinical practice. The 211 identified recommendations for COVID-19 management were classified into four topics: respiratory support(27), ARDS management(31), anti-viral or immunomodulatory therapy(95), or other medicines(58). Only 63% and 56% recommendations were supported by, respectively, assessment of the strength of recommendation or level of evidence. There were notable discrepancies between the different guidelines regarding the recommendations on COVID-19 management. Conclusions The quality of the guidelines for COVID-19 management is heterogeneous, and the recommendations are rarely supported by evidence.

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