The global objective of this coordinated project is to test the following hypotheses: 1) the lung microbiome in chronic obstructive pulmonary disease (COPD) is different in patients suffering from frequent exacerbations (FE) compared those who do not (NE ); 2) The microbial profile of patients with FE is associated with a different local and systemic inflammatory pattern; and 3) the inflammatory and immune characteristics of COPD are modulated by the intestinal microbiome.

The project is based on bronchoalveolar lavage (BAL) for sampling lung microbiome, and includes analysis of regional variability (intrapulmonary) and temporal variability. The project will also assess the correlation between BAL samples obtained from the proximal airway (oral cavity, oropharynx and sputum), and the representation of lung microbiome in them. A cohort of COPD patients (n = 50 FE; n = 50 NE) and healthy subjects (n= 30), matched by age, sex and tobacco consumption. Respiratory secretion samples will be collected in clinical stability samples, with resampling in a quarter of the participants at 6-9 months. Coordinator Project: Bacterial and fungal microbiota will be determined by 16S rRNA and ITS amplification and sequencing. Virome and functional metagenomics will be analyzed in a quarter of the participants. Subprojects: Regional variability in the lung, local and systemic inflammatory response, and the relationship between the intestinal microbiome and inflammatory and clinical characteristics of the disease will be determined. The integration of the results will be performed using network medicine methodologies. The results of this project will help to understand the pathogenesis of COPD and its exacerbations with the final aim to identify new therapeutic targets.

Inclusion Criteria:

• Spirometry: FEV1/FVC < 70%; FEV1 between 50 and 80% predicted (GOLD II/III)
• Clinical Stability (no therapeutic change and/or use of antibiotics) during 8 weeks. - The treatment received will be registered for post-hoc studies stratified by this condition.

Exclusion Criteria:

• Drug addiction, alcohol abuse,
• Use of long-term oral or nebulised antibiotic therapy.
• History of allergies, asthma or other chronic respiratory disease, sanitary worker, working exposure to dust or fumes.
• Other diseases: Severe cardiovascular, neurological, psychiatric, renal, hepatic or gastrointestinal , that might interfere with the daily life activities.

Eligible subjects were COPD patients GOLD II/III in stable situation.

Sequencing data will be available in public databases.