Emergence of AnnexinVpos CD31neg CD42blow/neg extracellular vesicles in plasma of humans at extreme altitude

Olaf Utermöhlen,Birgit Blissenbach,Tobias Merz,Jacqueline Pichler Hefti,Martin Krönke,Katja Wiegmann,Kristin Jakobshagen,Paula A. da Costa Martins

doi:10.1371/journal.pone.0220133

Abstract

BackgroundHypobaric hypoxia has been reported to cause endothelial cell and platelet dysfunction implicated in the formation of microvascular lesions, and in its extremes may contribute to vascular leakage in high altitude pulmonary edema or blood brain barrier disruption leading to cerebral micro-hemorrhage (MH). Platelet function in the development of microvascular lesions remained ill defined, and is still incompletely understood. In this study platelet- and endothelial cell-derived extracellular vesicles (PEV and EEV, respectively) and cell adhesion molecules were characterized in plasma samples of members of a high altitude expedition to delineate the contribution of platelets and endothelial cells to hypobaric hypoxia-induced vascular dysfunction.Methods and findingsIn this observational study, platelet and endothelial cell-derived extracellular vesicles were analysed by flow-cytometry in plasma samples from 39 mountaineers participating in a medical research climbing expedition to Himlung Himal, Nepal, 7,050m asl. Megakaryocyte/platelet-derived AnnexinVpos, PECAM-1 (CD31) and glycoprotein-1b (GP1b, CD42b) positive extracellular vesicles (PEV) constituted the predominant fraction of EV in plasma samples up to 6,050m asl. Exposure to an altitude of 7,050m led to a marked decline of CD31pos CD42neg EEV as well as of CD31pos CD42bpos PEV at the same time giving rise to a quantitatively prevailing CD31neg CD42blow/neg subpopulation of AnnexinVpos EV. An almost hundredfold increase in the numbers of this previously unrecognized population of CD31neg CD42blow/neg EV was observed in all participants reaching 7,050m asl.ConclusionsThe emergence of CD31neg CD42blow/neg EV was observed in all participants and thus represents an early hypoxic marker at extreme altitude. Since CD31 and CD42b are required for platelet-endothelial cell interactions, these hypobaric hypoxia-dependent quantitative and phenotypic changes of AnnexinVpos EV subpopulations may serve as early and sensitive indicators of compromised vascular homeostasis.

Highlights

Humans who permanently live or work at, as well as mountaineers climbing to, high altitudes are at risk of developing high-altitude diseases, such as chronic or acute mountain sickness (AMS), high-altitude pulmonary edema (HAPE) and high-altitude cerebral edema (HACE) [1, 2]. the pathophysiology of high altitude diseases is only incompletely understood, endothelial damage is a hallmark in each of the different diseases
In this study platelet- and endothelial cell-derived extracellular vesicles (PEV and EEV, respectively) and cell adhesion molecules were characterized in plasma samples of members of a high altitude expedition to delineate the contribution of platelets and endothelial cells to hypobaric hypoxiainduced vascular dysfunction
An almost hundredfold increase in the numbers of this previously unrecognized population of CD31neg CD42blow/neg EV was observed in all participants reaching 7,050m asl

Summary

Introduction

The pathophysiology of high altitude diseases is only incompletely understood, endothelial damage is a hallmark in each of the different diseases. In HACE, disruption of the blood-brain barrier is leading to edema formation and the characteristic micro-hemorrhages (MH). Hypobaric hypoxia has been reported to cause endothelial cell and platelet dysfunction implicated in the formation of microvascular lesions, and in its extremes may contribute to vascular leakage in high altitude pulmonary edema or blood brain barrier disruption leading to cerebral micro-hemorrhage (MH). In this study platelet- and endothelial cell-derived extracellular vesicles (PEV and EEV, respectively) and cell adhesion molecules were characterized in plasma samples of members of a high altitude expedition to delineate the contribution of platelets and endothelial cells to hypobaric hypoxiainduced vascular dysfunction

Methods

Results

Conclusion