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Monocytes mediate homing of circulating microvesicles to the pulmonary vasculature during low-grade systemic inflammation

O'Dea, Kieran P; Tan, Ying Ying; Shah, Sneh; Patel, Brijesh; Tatham, Kate C; Wilson, Mike R; Soni, Sanooj; (2020) Monocytes mediate homing of circulating microvesicles to the pulmonary vasculature during low-grade systemic inflammation. Journal of Extracellular Vesicles , 9 (1) , Article 1706708. 10.1080/20013078.2019.1706708. Green open access

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Abstract

Microvesicles (MVs), a plasma membrane-derived subclass of extracellular vesicles, are produced and released into the circulation during systemic inflammation, yet little is known of cell/tissue-specific uptake of MVs under these conditions. We hypothesized that monocytes contribute to uptake of circulating MVs and that their increased margination to the pulmonary circulation and functional priming during systemic inflammation produces substantive changes to the systemic MV homing profile. Cellular uptake of i.v.-injected, fluorescently labelled MVs (J774.1 macrophage-derived) in vivo was quantified by flow cytometry in vascular cell populations of the lungs, liver and spleen of C57BL6 mice. Under normal conditions, both Ly6Chigh and Ly6Clow monocytes contributed to MV uptake but liver Kupffer cells were the dominant target cell population. Following induction of sub-clinical endotoxemia with low-dose i.v. LPS, MV uptake by lung-marginated Ly6Chigh monocytes increased markedly, both at the individual cell level (~2.5-fold) and through substantive expansion of their numbers (~8-fold), whereas uptake by splenic macrophages was unchanged and uptake by Kupffer cells actually decreased (~50%). Further analysis of MV uptake within the pulmonary vasculature using a combined model approach of in vivo macrophage depletion, ex vivo isolated perfused lungs and in vitro lung perfusate cell-based assays, indicated that Ly6Chigh monocytes possess a high MV uptake capacity (equivalent to Kupffer cells), that is enhanced directly by endotoxemia and ablated in the presence of phosphatidylserine (PS)-enriched liposomes and β3 integrin receptor blocking peptide. Accordingly, i.v.-injected PS-enriched liposomes underwent a redistribution of cellular uptake during endotoxemia similar to MVs, with enhanced uptake by Ly6Chigh monocytes and reduced uptake by Kupffer cells. These findings indicate that monocytes, particularly lung-marginated Ly6Chigh subset monocytes, become a dominant target cell population for MVs during systemic inflammation, with significant implications for the function and targeting of endogenous and therapeutically administered MVs, lending novel insights into the pathophysiology of pulmonary vascular inflammation.

Type: Article
Title: Monocytes mediate homing of circulating microvesicles to the pulmonary vasculature during low-grade systemic inflammation
Location: United States
Open access status: An open access version is available from UCL Discovery
DOI: 10.1080/20013078.2019.1706708
Publisher version: https://doi.org/10.1080/20013078.2019.1706708
Language: English
Additional information: © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group on behalf of The International Society for Extracellular Vesicles. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Keywords: Extracellular vesicles; microvesicles; monocytes; systemic inflammation; pulmonary vasculature
UCL classification: UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Infection and Immunity
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL
URI: https://discovery.ucl.ac.uk/id/eprint/10144781
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