Saliva as a “patient-friendly” specimen for COPD assessment

Bronchoalveolar lavage (BAL) and sputum samples are commony used to provide valuable information on airway microbiota of COPD but they are too invasive to be routinely collected. An interesting alternative would be the use of non-invasive samples from the upper airways but its validation is still lacking. Here, we have explored the merits of saliva to identify the typical profile of COPD microbiota. 70 patients with COPD (60 male, 68±9y, BMI 25.5±3.5, FEV1pp 48±16, GOLD A-12, B-32, C-5, D-21) and 50 healthy matched controls (42 male, 67±8y, BMI 27.6±3.8, FEV1pp 103±17) were characterised based on sociodemographic, anthropometric, clinical parameters and 16S rRNA profiling of their salivary microbiota. Microbiota composition was significantly different between healthy individuals and patients with COPD and could also descriminate moderate from severe patients. Healthy individuals were enriched in Alloprevotella and Prevotella, both Bacteroidetes’ genera, whereas moderate patients were enriched in Granullicatella and Lachnoanaerobaculum (Firmicutes) and  severe patients were significantly enriched in Haemophilus (Proteobacteria) (Fig1.A). Furthermore, patients showed a significantly less diverse microbiota than healthy individuals (MW-U, p=0.001) (Fig1.B). Our results corroborate the findings reported previously using BAL and sputum samples encouraging further exploration of salivary microbiota as a potential disease biomarker.