Date of Award

Spring 8-31-2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Christopher A. DeSouza

Second Advisor

Robert S. Mazzeo

Third Advisor

Christopher D. Link

Fourth Advisor

Kenneth P. Wright

Fifth Advisor

Brian L. Stauffer

Abstract

Microparticles and miRNA represent novel mediators and effectors of endothelial cell function and, in-turn, vascular health. MicroRNAs (miRNAs or miRs) are short (20-22 nucleotide) non-coding RNAs involved in the homeostatic regulation of ~60% of all gene expression. miRNAs are transferred and regulated by microparticles, small anucleoid extracellular vesicles. Alteration of cellular miRNA expression by microparticles has been mechanistically linked with the pathogenesis and progression of atherosclerotic cardiovascular disease (ASCVD). Human immunodeficiency virus (HIV)-1 infection is associated with an increased risk and prevalence of ASCVD due, in-part, to endothelial cell damage and dysfunction. Interestingly, endothelial cells are neither targets nor reservoirs of the virus. As such, the detrimental effects of HIV-1 on endothelial cell function are complex, multifactorial and poorly understood. There are currently no data regarding the direct or indirect effects of HIV-1 on microparticle and miRNA biology. Accordingly, the aims of this dissertation were to determine: 1) the effect of HIV-1 related proteins gp120 and Tat on endothelial cell senescence and expression of senescence-associated miRNA; 2) if HIV-1 gp120 and Tat stimulate the release of endothelial microparticles in vitro and if viral protein induced microparticles adversely affect endothelial cell function; and 3) whether circulating microparticles are elevated in HIV-1-seropositive adults. In addition, we determined the effects of microparticles from HIV-1-seropositive adults on endothelial cell activation, inflammation, oxidative stress, senescence and apoptosis, in vitro. To address these aims, we conducted three independent, sequential studies integrating basic and clinical approaches to optimize the translational potential of this work. The seminal and novel findings of these studies are that: 1) HIV-1 gp120 and Tat accelerate cellular senescence due, in part, to dysregulation of senescence-specific miRNA; 2) HIV-1 gp120 and Tat induce microparticle release from endothelial cells and these microparticles confer pathologic effects on endothelial cells enhancing inflammation, oxidative stress, senescence and apoptosis as well as altering cellular miRNA expression; and 3) circulating levels of microparticles are higher in HIV-1-seropositive adults and these microparticles induce a proatherogenic endothelial phenotype.

Available for download on Sunday, October 10, 2021

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