Soni, SSSoniWilson, MRMRWilsonO'Dea, KPKPO'DeaYoshida, MMYoshidaKatbeh, UUKatbehWoods, SSWoodsTakata, MMTakata2016-05-102016-06-102016-10-13Thorax, 2016, 71 (11), pp.1020-10291468-3296http://hdl.handle.net/10044/1/32370Background Microvesicles (MVs) are important mediators of intercellular communication, packaging a variety of molecular cargo. They have been implicated in the pathophysiology of various inflammatory diseases; yet, their role in acute lung injury (ALI) remains unknown. Objectives We aimed to identify the biological activity and functional role of intra-alveolar MVs in ALI. Methods Lipopolysaccharide (LPS) was instilled intratracheally into C57BL/6 mice, and MV populations in bronchoalveolar lavage fluid (BALF) were evaluated. BALF MVs were isolated 1 hour post LPS, assessed for cytokine content and incubated with murine lung epithelial (MLE-12) cells. In separate experiments, primary alveolar macrophage-derived MVs were incubated with MLE-12 cells or instilled intratracheally into mice. Results Alveolar macrophages and epithelial cells rapidly released MVs into the alveoli following LPS. At 1 hour, the dominant population was alveolar macrophage-derived, and these MVs carried substantive amounts of tumour necrosis factor (TNF) but minimal amounts of IL-1β/IL-6. Incubation of these mixed MVs with MLE-12 cells induced epithelial intercellular adhesion molecule-1 (ICAM-1) expression and keratinocyte-derived cytokine release compared with MVs from untreated mice (p<0.001). MVs released in vitro from LPS-primed alveolar macrophages caused similar increases in MLE-12 ICAM-1 expression, which was mediated by TNF. When instilled intratracheally into mice, these MVs induced increases in BALF neutrophils, protein and epithelial cell ICAM-1 expression (p<0.05). Conclusions We demonstrate, for the first time, the sequential production of MVs from different intra-alveolar precursor cells during the early phase of ALI. Our findings suggest that alveolar macrophage-derived MVs, which carry biologically active TNF, may play an important role in initiating ALI.This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See: http://creativecommons.org/licenses/ by/4.0/Science & TechnologyLife Sciences & BiomedicineRespiratory SystemRESPIRATORY-DISTRESS-SYNDROMEEPITHELIAL-CELLSEXTRACELLULAR VESICLESENDOTHELIAL-CELLSTNF-ALPHAMICROPARTICLESINFLAMMATIONACTIVATIONEXPRESSIONRELEASEARDSCytokine BiologyMacrophage BiologyAcute Lung InjuryAnimalsBronchoalveolar Lavage FluidCell-Derived MicroparticlesCytokinesLipopolysaccharidesMacrophages, AlveolarMiceMice, Inbred C57BLMacrophages, AlveolarBronchoalveolar Lavage FluidAnimalsMice, Inbred C57BLMiceLipopolysaccharidesCytokinesCell-Derived MicroparticlesAcute Lung Injury1103 Clinical SciencesRespiratory SystemJournal Articlehttps://www.dx.doi.org/10.1136/thoraxjnl-2015-208032MR/M018164/1Capacity Building Project