Zachary Boodoo - Graduate Student
Even on combined antiretroviral therapy (cART), people living with HIV (PLWH) experience a low level of viral replication that engenders a chronic inflammatory state and increases their risk to develop multiple types of vascular disease. Previous work by our lab has demonstrated platelet-monocyte complexes (PMCs) occur with greater frequency in PLWH due to aberrant platelet activation, and these complexes are associated with higher expression of monocyte activation markers, as well as pro-inflammatory CD16+ intermediate and non-classical monocyte (NCM) phenotypes. However, the fate of PMCs in the vascular disease microenvironment, and the platelet-induced transcriptional networks that lead to cellular dysfunction, are not well characterized.
Considering these unknown entities, we implemented a study cohort to investigate the effects of chronic HIV infection on vascular disease (atherosclerosis). Participants were age-, sex-, and Reynolds risk score-matched and divided into four subgroups based on their HIV and AS status (HIV-AS-, HIV+AS-, HIV-AS+, and HIV+AS+) (n=32). Monocytes were isolated from participant PBMC or whole blood samples via flow-activated cell sorting (FACS) and analyzed by single cell RNA sequencing (scRNA-seq). Unbiased clustering revealed 10 monocyte subsets that were conserved across participants groups, two of which were identified as PMCs based on an enrichment of platelet-associated transcripts. Differential gene expression (DGE) analysis of PMCs in PLWH and AS together compared to people living with AS (PLWAS) alone revealed an upregulation of genes involved inflammatory responses (antigen processing and presentation, chemokine signaling pathway), lipid metabolism (arachidonic acid metabolism, ABC transporters, alpha linoleic acid metabolism), and cardiovascular function (cardiac muscle contraction, arrhythmogenic right ventricular cardiomyopathy). Mass spectrometry of participant plasma samples revealed differentially abundant proteins associated with vascular disease processes. Stabilin-1, a macrophage and endothelial cell scavenger receptor with atheroprotective effects, and angiopoietin-like 4 (ANGPLT4), a pro-resolving factor in an inflamed intima environment, were less abundant or entirely absent in the plasma of HIV+AS+ participants compared to those who are single-afflicted or healthy controls. Myotrophin, a myocardial hypertrophy-inducing factor elevated in people who have experienced heart failure, and serum amyloid A2, a well-characterized local mediator of atherosclerosis and vascular dysfunction, were elevated in HIV+AS+ participants.
Oxidized lipoprotein (oxLDL), a key mediator of atherosclerosis, has been demonstrated to incur epigenetic changes in monocytes that alter its response to future inflammatory stimuli. To determine the effect of platelet interactions on this trained immunity paradigm, monocytes and collagen-activated platelets were cocultured for seven days with or without oxLDL, and stimulated with LPS at day six. Flow cytometric analysis of monocyte-derived macrophages revealed that platelet interactions decreased CD36 (scavenger receptor) and CD14 expression, and increased expression of antigen-presentation molecule CD86. CD40 expression was similar between non-PMCs and PMCs, but LPS-stimulation reduced expression in PMCs relative to non-PMCs. Collectively, these results demonstrate that platelets alter monocyte-macrophage phenotypes, and PMC gene signatures in PLWH and AS are proinflammatory. In-depth understanding of platelet-mediated monocyte dysfunction in HIV infection can pave the way to develop potential therapeutic approaches to address viral-associated vascular disease and related comorbidities
Sep 19, 2024 @ 12:00 p.m.
Medical Center | K307 (3-6408)
Host: Advisors: Meera Singh, PhD and Juilee Thakar, PhD