Lipidomic Profiling of Bronchoalveolar Lavage Fluid Extracellular Vesicles Indicates Their Involvement in Lipopolysaccharide-Induced Acute Lung Injury

Abstract

Emerging data support the pivotal role of extracellular vesicles (EVs) in normal cellular physiology and disease conditions. However, despite their abundance, there is much less information about the lipid mediators carried in EVs, especially in the context of acute lung injury (ALI). Our data demonstrate that C57BL/6 mice subjected to intranasal <i>Escherichia coli</i> lipopolysaccharide (LPS)-induced ALI release, a higher number of EVs into the alveolar space, compared to saline-treated controls. EVs released during ALI originated from alveolar epithelial cells, macrophages, and neutrophils and carry a diverse array of lipid mediators derived from ω-3 and ω-6 polyunsaturated fatty acids (PUFA). The eicosanoids in EVs correlated with cellular levels of arachidonic acid, expression of cytosolic phospholipase A2, cyclooxygenase (COX), lipoxygenase (LOX), and cytochrome epoxygenase p450 proteins in pulmonary macrophages. Furthermore, EVs from LPS-toll-like receptor 4 knockout (TLR4<sup>-/-</sup>) mice contained significantly lower amounts of COX and LOX catalyzed eicosanoids and ω-3 PUFA metabolites. More importantly, EVs from LPS-treated wild-type mice increased TNF-α release by macrophages and reduced alveolar epithelial monolayer barrier integrity compared to EVs from LPS-treated TLR4<sup>−/−</sup> mice. In summary, our study demonstrates for the first time that the EV carried PUFA metabolite profile in part depends on the inflammatory status of the lung macrophages and modulates pulmonary macrophage and alveolar epithelial cell function during LPS-induced ALI.

Metabolomics of Extracellular Vesicles: A Future Promise of Multiple Clinical Applications

“…Furthermore, when alveolar macrophages stay in different inflammatory conditions, the content of eicosanoic acid, arachidonic acid, cytosolic phospholipase A2, and cyclooxygenase in EVs will change diversely. 56 The results reveal that inflammation can mediate metabolic pathway changes in EVs. Meanwhile, molecules in EVs can also regulate cellular inflammation.…”

“…An increasing number of studies have declaimed the participation of EVs in metabolic syndromes. For example, flow cytometry has been used to show that plasma-EVs are increased in diabetes and non-alcoholic fatty liver disease 51 supplying lactate and lipids, 44 regulating immune response, 45 promoting pre-metastatic niche, [46][47][48][49][50] mediating metabolic pathway, 56 boosting more EVs releasing, [40][41][42] joining in EVs intrinsic metabolic reactions, 48 promoting obesity and atherosclerosis, 50 transferring lipids to adjacent cells and initiating cancer development. 58…”

“…Figure 2Schematic representation of the impact of metabolites in EVs on the hallmarks of different diseases. Ten hallmark capabilities are as follows: accelerating cancer invasion and metastasis,51 supplying lactate and lipids,44 regulating immune response,45 promoting pre-metastatic niche,[46][47][48][49][50] mediating metabolic pathway,56 boosting more EVs releasing,[40][41][42] joining in EVs intrinsic metabolic reactions,48 promoting obesity and atherosclerosis,50 transferring lipids to adjacent cells and initiating cancer development 58. Created with BioRender.com.…”

Isolation of Extracellular Vesicles From the Bronchoalveolar Lavage Fluid of Healthy and Asthmatic Horses

“…EV communication occurs through EV surface receptors and endocytosis by the cells or by fusion of the EV and cell membranes (6). In a recent study by Nirujogi et al (2022) on mice BALF, acute lung injury increased the release of EVs (10). In asthma, EVs are mostly recognized to promote remodeling and to disseminate inflammation by upregulating and activating proinflammatory responses, however, there are also research data supporting anti-inflammatory activity of EVs (11,12).…”

“…In asthma, EVs are mostly recognized to promote remodeling and to disseminate inflammation by upregulating and activating proinflammatory responses, however, there are also research data supporting anti-inflammatory activity of EVs ( 11 , 12 ). Additionally, EVs originate from different cells, such as eosinophils, mast cells, and neutrophils, according to disease type ( 10 , 12 ). EVs have potential as biomarkers for diseases and as therapeutic agents due to their proinflammatory and immune system triggering properties ( 13 – 15 ).…”