Abstract

Diagnosis of interstitial lung diseases (ILD) is difficult to perform. Extracellular vesicles (EVs) facilitate cell-to-cell communication. Our goal aimed to investigate EVs markers in bronchoalveolar lavage (BAL) from idiopathic pulmonary fibrosis (IPF), sarcoidosis and hypersensitivity pneumonitis (HP) patients. Study cohort included 83 (mean age±standard deviation (MA±SD) 65±23.4) patients from the ILD Referral Center of Siena University. Two validation cohorts were enrolled: 21 patients (MA±SD, 61±18.3) and 44 patients (MA±SD, 62±19.5) referred to ILD clinic at Barcelona Hospital and Foggia University, respectively. EVs were isolated by BAL samples and characterized by flow cytometry assay through MACSPlex Exsome KIT. All cohorts showed a prevalence of males in IPF than other ILD (p=0.0312), while younger female prevalence was in sarcoidosis cohort (p=0.0121). Majority of alveolar EVs markers were related to the fibrotic damage: CD56, CD105, CD142, CD31 and CD49e were exclusively expressed by IPF alveolar samples, while HP showed only CD86 and CD24. Some EVs markers were in common between HP and sarcoidosis (CD11c, CD1c, CD209, CD4, CD40, CD44, CD8). Principal Component Analysis distinguished the three groups based on EVs markers with total variance of 60.08%. This study has demonstrated the validity of the flow cytometric method to phenotype and characterize EVs surface markers in BAL samples. The two granulomatous disease, sarcoidosis and HP cohorts shared alveolar EVs markers not revealed in IPF patients. Our findings demonstrated the viability of the alveolar compartment allowing to identify lung-specific markers for IPF and HP