Immune-Associated Proteins Are Enriched in Lung Tissue-Derived Extracellular Vesicles during Allergen-Induced Eosinophilic Airway Inflammation.

Studying the proteomes of tissue-derived extracellular vesicles (EVs) can lead to the identification of biomarkers of disease and can provide a better understanding of cell-to-cell communication in both healthy and diseased tissue. The aim of this study was to apply our previously established tissue-derived EV isolation protocol to mouse lungs in order to determine the changes in the proteomes of lung tissue-derived EVs during allergen-induced eosinophilic airway inflammation. A mouse model for allergic airway inflammation was used by sensitizing the mice intraperitoneal with ovalbumin (OVA), and one week after the final sensitization, the mice were challenged intranasal with OVA or PBS. The animals were sacrificed 24 h after the final challenge, and their lungs were removed and sliced into smaller pieces that were incubated in culture media with DNase I and Collagenase D for 30 min at 37 °C. Vesicles were isolated from the medium by ultracentrifugation and bottom-loaded iodixanol density cushions, and the proteomes were determined using quantitative mass spectrometry. More EVs were present in the lungs of the OVA-challenged mice compared to the PBS-challenged control mice. In total, 4510 proteins were quantified in all samples. Among them, over 1000 proteins were significantly altered (fold change >2), with 614 proteins being increased and 425 proteins being decreased in the EVs from OVA-challenged mice compared to EVs from PBS-challenged animals. The associated cellular components and biological processes were analyzed for the altered EV proteins, and the proteins enriched during allergen-induced airway inflammation were mainly associated with gene ontology (GO) terms related to immune responses. In conclusion, EVs can be isolated from mouse lung tissue, and the EVs' proteomes undergo changes in response to allergen-induced airway inflammation. This suggests that the composition of lung-derived EVs is altered in diseases associated with inflammation of the lung, which may have implications in type-2 driven eosinophilic asthma pathogenesis.