Saturday, May 4, 2024
5/4/2024
People living with HIV (PLWH) have a significantly higher risk of cardiovascular diseases (CVD) compared to their HIV negative counterparts. However, the underlying mechanisms that drive this increased CVD risk remain elusive. Extracellular vesicles (EVs)/exosomes are released by all cells and widely distributed in plasma, urine, and other biological fluids. EVs contain diverse bioactive molecules, including mRNAs, microRNAs (miRs), proteins, and lipids, which can be transferred to target cells altering their functionality. The cargo of EVs reflects the pathophysiological states of the host cells. It is conceivable that the latent HIV reservoir established during early infection, long-term exposure to antiretroviral therapy (ART), and chronic immune activation/inflammation (referred to as HIV positivity for grant writing purpose) may impact host cells, particularly those in the peripheral blood, altering the release and the cargo of plasma EVs. These EVs in turn may serve as information vehicles for cell-to-cell communication, affecting cells of the arterial wall, including endothelial cells (ECs) and smooth muscle cells (SMCs), as well as endothelial progenitor cells (EPCs) in the bone marrow, promoting atherogenesis. To test this hypothesis, we fractionated plasma from PLWH on ART with undetectable viral load into plasma EVs (HIVposEVs) and plasma-depleted of EVs (HIVplasmadepEVs) and injected these fractions into atherogenic apoE-/- mice. Remarkably, HIVposEVs, but not HIVplasmadepEVs, increased atherosclerosis plaque burden compared to EVs isolated from HIV negative subjects (HIVnegEVs) and PBS. These changes were accompanied by increased senescence and apoptosis of ECs and SMCs in the arterial wall and impaired viability and functionality of bone marrow EPCs. These exciting data support the hypothesis that circulating EVs from PLWH reconstitute the effects of HIV positivity (without active HIV infection) on atherosclerosis. RNA-seq in HIVposEVs and HIVnegEVs revealed differential miR profiles. The target genes of EV-miRs overrepresented in PLWH are enriched in cardiovascular pathology pathways. We have engineered tailored EVs (TEVs) that are loaded with the antagomirs for let-7b-5p and miR103a-2, two candidate EV-miRs overrepresented in HIVposEVs by transducing mesenchymal stromal cells. These TEVs counteracted the effects of HIVposEVs on the accelerated senescence of EPCs, whereas let-7b- 5p overexpressing EVs recapitulated, in part, the effects of HIVposEVs. Furthermore, EPCs overexpressing HMGA2 (a top let-7b-5p target gene) lacking the 3'UTR (resistant to miR regulation) showed protection similar to miRZip-let-7b TEVs against HIVposEVs-induced senescence. In this proposal, we will determine if TEVs engineered to modulate key HIVposEVs-associated miRs counteract the effects of the chronic inflammation and immune activation, ART, and latent HIV reservoir associated with HIV positivity on atherosclerosis development. In addition, we will further dissect the mechanisms underlying the adverse effect of HIV positivity on the cardiovascular system by examining the effects of HIVposEVs and/or TEVs on the functionality and transcriptome of ECs, SMCs and EPCs. We will identify putative miR-mRNA pathways. Importantly, we will validate our mouse findings in EPC samples from PLWH using TEVs, direct miR antagonism, and target gene overexpression approaches.
HHS’ Tracking Accountability in Government Grants System (TAGGS) website provides access to detailed descriptions of grants, loans, aggregated direct payments and other types of financial assistance awarded by the HHS Operating Divisions (OPDIVs) and the Office of the Secretary Staff Divisions (STAFFDIVs).
