Extracellular Microvesicles Released From Brain Endothelial Cells are Detected in Animal Models Of HIV-1 Signifying Unresolved Inflammation

Jonathan F Hale,Allison M Andrews,Bryson Hoover-Hankerson,Lishan Su,Tetyana P Buzhdygan,Raghava Potula,Servio H Ramirez,Roshanak Razmpour,Uma Sriram,Liang Cheng,Guangming Li

doi:10.1007/s11481-021-10008-5

Abstract

Treatment of HIV-infected patients with antiretroviral therapy (ART) has effectively suppressed viral replication; however, the central nervous system is still a major target and reservoir of the virus leading to the possible development of HIV-associated neurocognitive disorders (HAND). Furthermore, a hallmark feature of HAND is the disruption of the blood–brain barrier that leads to loss of tight junction protein (TJP) complexes. Extracellular vesicles (EVs), released by every cell type in the body, occur in greater quantities in response to cellular activation or injury. We have found that inflammatory insults activate brain endothelial cells (EC) and induce the release of EVs containing TJPs such as Occludin. We thus hypothesized that HIV infection and unresolved neuroinflammation will result in the release of brain-EC derived EVs. Herein, our results show elevated levels of brain-EC EVs in a humanized mouse model of HIV infection. Furthermore, while ART reduced brain-EC EVs, it was unable to completely resolve increased vesicles detectable in the blood. In addition to inflammatory insults, HIV-1 viral proteins (Tat and gp120) increased the release of Occludin + vesicles from human brain microvasculature ECs. This increase in vesicle release could be prevented by knock-down of the small GTPase ARF6. ARF6 has been shown to regulate EV biogenesis in other cell types, and we provide further evidence for the involvement of ARF6 in brain EC derived EVs. Overall, this study offers insight into the process of brain vascular remodeling (via EVs) in the setting of neuroinflammation and thus provides possibilities for biomarker monitoring and targeting of ARF6.Graphical abstract

Highlights

The use of antiretroviral therapy has reduced the prevalence of HIV-associated dementia (HAD), the overall rates of HIV-associated neurocognitive disorders (HAND)remains unchanged (Saylor et al 2016)
We have previously reported that neuroinflammation in vivo (Andrews et al 2016) and primary human brain microvascular endothelial cells (hBMVECs) exposed to HIV viral proteins (Ramirez et al 2018) produce vesicles containing tight junction proteins
To evaluate whether MVs released from the brain vasculature occurs during HIV-1 infection analysis was performed in relevant animal models

Summary

Introduction

Underlying these disorders is the notion that immune activation, neuroinflammation and disruption of the blood–brain barrier (BBB) play a central role in the development of HAND (Chaganti et al 2019). EVs are released or secreted in response to stimuli, injury, or activation from a number of cell types (platelets, immune cells and ECs) (Boulanger et al 2006). HIV-1 infection or viroproteins triggers the production of MVs from various cell types, including but not limited to monocytes (Weber et al 2020; Kadiu et al 2012), microglia (Wu et al 2015), platelets (Poveda et al 2020), and peripheral ECs (Hijmans et al 2019a). Studies have shown that HIV-1 promotes MV production from distinct cell populations, limited information is available regarding the cells that form the BBB

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