In the longtime challenge of identifying specific, easily-detectable and reliable biomarkers of Idiopathic Pulmonary Fibrosis (IPF), bronchoalveolar lavage fluid (BALF) proteomics is providing interesting new insights into its pathogenesis. To the best of our knowledge, the present study is the first shotgun proteomic investigation of EVs isolated from BALF of IPF patients. Our main aim was to characterize the proteome of the vesicular component of BALF and to explore its individual impact on the pathogenesis of IPF. To this purpose, ultracentrifugation was chosen as EVs isolation technique and their purification was assessed by TEM, 2DE and LC-MS/MS. Our 2DE data and scatter plots showed considerable differences between the proteome of EVs and that of whole BALF and of its fluid component. Analysis of protein content and protein functions evidenced that EV proteins are predominantly involved in cytoskeleton remodeling, adenosine signaling, adrenergic signaling, C-peptide signaling and lipid metabolism. Our findings may suggest a wider system involvement in the disease pathogenesis and support the importance of pre-fractioning of complex samples, like BALF, in order to let low-abundant proteins-mediated pathways to emerge.

Background: Chronic Obstructive Pulmonary Disease (COPD) and Idiopathic Pulmonary Fibrosis (IPF) are chronic, progressive lung ailments which are characterized by distinct pathologies. Early detection biomarkers and disease mechanisms for these debilitating diseases are lacking. Exosomes are small extracellular vesicles attributed to carry proteins, mRNA, miRNA and sncRNA to facilitate cell-to-cell communication under normal and diseased conditions. Exosomal miRNAs have been studied in relation to many diseases. However, there is little to no knowledge regarding the miRNA population of BALF or the lung tissue derived exosomes in COPD and IPF. Here, we determined and compared the miRNA profiles of BALF and lung tissue-derived exosomes from healthy non-smokers, healthy smokers, and patients with COPD and IPF in independent cohorts. Results: Exosome characterization using NanoSight particle tracking and TEM demonstrated that the BALF-derived exosomes were approximately 89.85 nm in size and ~2.95 X 1010 particles/mL. Lung-derived exosomes were ~146.04 nm in size and ~2.38 X 1011 particles/mL. NGS results identified three differentially expressed miRNAs in the BALF, while one in the lung-derived exosomes from COPD patients as compared to healthy non-smokers. Of these, three- and five-fold downregulation of miR-122-5p amongst the lung tissue-derived exosomes from COPD patients as compared to healthy non-smokers and smokers, respectively. Interestingly, there were key 55 differentially expressed miRNAs in the lung tissue-derived exosomes of IPF patients compared to non-smoking controls. Conclusions: Overall, we identified specific miRNAs to develop as biomarkers or targets for pathogenesis of these chronic lung diseases.

Idiopathic Pulmonary Fibrosis (IPF) is most common idiopathic interstitial pneumonia. IPF is often seen in elderly men who smoke. Diagnosis of IPF requires integration of a detailed clinical history, specific physical examination, laboratory findings, pulmonary function tests, high-resolution computed tomography (HRCT) of the chest, and histopathology. IPF has a heterogeneous clinical course, from an asymptomatic stable state to progressive respiratory failure or acute exacerbation (AE). AE of IPF has several important differential diagnoses, such as heart failure and volume overload. The International working project proposed new criteria of AE of IPF in 2016 dividing it into triggered and idiopathic AE. On the basis of these criteria, physicians can detect AE of IPF more easily. The recent international IPF guideline emphasized the utility of chest HRCT. In addition, two anti-fibrotic agents have become available. We should attend not only to management of AE, but also to its prevention. The diagnostic process, laboratory findings, typical chest imaging, management and prognosis of AE are comprehensively reviewed.

Idiopathic lung fibrosis (IPF) is a progressive and fatal degenerative lung disease of unknown etiology. Although in its final stages it implicates in a reactive manner all lung cell types, the initial damage involves the alveolar epithelial compartment, in particular the alveolar epithelial type 2 cells (AEC2s). AEC2s serve dual progenitor and surfactant secreting functions, both of which are deeply impacted in IPF. Thus, we hypothesize that the size of the surfactant processing compartment, as measured by Lysotracker incorporation, allows the identification of different epithelial states in the IPF lung. Flow cytometry analysis of epithelial Lysotracker incorporation delineates two populations (Lysohigh and Lysolow) of AEC2s which behave in a compensatory manner during bleomycin injury and in the donor/IPF lung. Employing flow cytometry and transcriptomic analysis of cells isolated from donor and IPF lungs, we demonstrate that the Lysohigh population expresses all classical AEC2 markers and is drastically diminished in IPF. The Lysolow population, which is increased in proportion in IPF, co-expresses AEC2s and basal cell markers resembling the phenotype of the previously identified intermediate AEC2 population in the IPF lung. In that regard, we provide an in-depth flow-cytometry characterization of Lysotracker uptake, HTII-280, proSP-C, mature SP-B, NGFR, KRT5 and CD24 expression in human lung epithelial cells. Combining functional analysis with extra- and intra- cellular marker expression and transcriptomic analysis, we advance the current understanding of epithelial cell behavior and fate in lung fibrosis.