The Gut-Airways Microbiome axis in COPD

<bold>Background:</bold> In Chronic Obstructive Pulmonary Disease (COPD) alterations in the airways microbiome (dysbiosis) have been related to the severity of airflow limitation and frequency of exacerbations. No previous study, however, has characterized simultaneously the airway microbiome of the upper and lower airways and the gut. <bold>Methods:</bold> Prospective, multicentre, cross-sectional study including clinically stable COPD patients (n=60) and healthy volunteers (n=30) as controls in whom we 1) determined the microbiome composition in oropharyngeal (OP) swabs, sputum, bronchoalveolar lavage fluid (BALF) and stool samples using 16s rRNA-seq and 2) applied weighted gene co-expression network analysis (WGCNA) to identify groups of highly co-abundant bacteria (modules) and explore their association with FEV1, exacerbations, eosinophilia and inhaled steroids use (ICS). <bold>Results:</bold> We found that: 1) the microbiome was different in COPD patients vs. controls (p<0.05) and across different compartments (Fig. 1). Interestingly, sputum and OP swabs presented similar bacterial composition, while stool presented the most different one; 2) WGCNA identified 8 to 12 modules in each sample type. In OP swabs and sputum half of the modules were associated with FEV1, dyspnea, exacerbations and ICS use. In BALF 4 modules were linked to FEV1 and dyspnea but only 2 to ICS use. In stool 1 module was related to FEV1 but 5 to ICS use. <bold>Conclusion:</bold> In stable COPD patients the microbiome varies across different body locations. However, different bacterial co-expressed communities can be found across body locations, and they are associated with relevant clinical features, supporting a role of microbiome dysbiosis in COPD. <bold>Funding:</bold> Fundació Pla Armengol, Fondo de Investigaciones Sanitarias