Investigating plasma cell-free hemoglobin as a driver of cardiovascular disease risk in HIV-positive individuals

The National Institute of Allergy and Infectious Diseases awarded Case Western Reserve University $235,500 on April 17, 2026, under the Allergy and Infectious Diseases Research program (CFDA 93.855) to investigate plasma cell-free hemoglobin and red blood cell-derived extracellular vesicles as drivers of cardiovascular disease risk in people with HIV.

The research addresses a gap in understanding why HIV-positive individuals face a twofold higher cardiovascular disease risk despite effective antiretroviral treatment and statin therapy that reduces risk by up to 35 percent. The project will quantify and characterize red blood cell-derived extracellular vesicles containing cell-free hemoglobin in virologically controlled HIV patients, examining their impact on endothelial cell dysfunction and platelet hyperreactivity. The study aims to identify novel translational approaches to mitigate endothelial dysfunction and chronic inflammation in this population.

Case Western Reserve University's Office of Research Administration, operating in affiliation with University Hospitals of Cleveland, serves as the recipient. Work is performed in Cleveland, Ohio. The period of performance runs from April 17, 2026 through March 31, 2028. The assistance type is a Project Grant, which supports biomedical research and research training in infectious diseases and related areas at nonprofit institutions.

Abstract

People with HIV (PWH) face persistent low-grade inflammation, pro-active blood clotting mechanisms, and a twofold higher risk of cardiovascular disease despite effective anti-HIV treatments. A recent clinical trial showed that statins reduce cardiovascular disease risks by up to 35%, but PWH still face higher risks than non-HIV individuals, revealing gaps in our understanding cardiovascular disease pathogenesis. The persistence of cell free hemoglobin (CFH) above normal physiological thresholds in virologically controlled PWH may be an underappreciated factor contributing to the chronic immune activation and a pro-thrombotic state. To date, a comprehensive knowledge of the causes and pathobiological significance of red blood cell-derived extracellular vesicles (revs) containing cell-free hemoglobin in PWH remains elusive. Furthermore, the potential impact of these vesicles on endothelial cells and platelets - resulting in endothelial dysfunction and platelet hyperreactivity - is inadequately understood, despite their association with an increased likelihood of cardiovascular disease pathogenesis in hemolytic anemias without HIV. This proposal centers on the hypothesis that extracellular vesicles, particularly revs, might be an additional contributor to endothelial dysfunction and platelet activation in PWH. By addressing this, this study aims to shed light on a previously less recognized CVD risk factor in PWH and would reveal novel translational approaches to mitigate endothelial dysfunction and chronic inflammations. Our central innovation lies in investigating the ability of revs and REV- associated cell free hemoglobin to trigger endothelial and platelet responses, a novel focus that could fill significant knowledge gaps regarding residual cardiovascular disease. In this project's we initially plan to quantify and characterize revs and REV-associated CFH in PWH and the uninfected control samples and to examine their capacity to elicit endothelial dysfunction and platelet activation by EX vivo experiments. The study will explore correlations between REV-associated cell free hemoglobin levels and chronic inflammation in PWH. IT will investigate whether revs cause endothelial dysfunction through free radicals, reactive oxygen species, and TLR4 signaling. Specific aim 1 involves isolating and analyzing revs from PWH and non-HIV controls to test if PWH have higher REV-bound CFH levels, along with assessing pro-inflammatory cytokine levels. In specific aim 2, EX vivo studies will use human aortic endothelial cells and GEL-purified platelets to examine REV-driven dysfunction and activation using gene sequencing, flow cytometry, and seahorse metabolic assays. The study will leverage DE-identified plasma from the center for aids research sample repository at case western reserve university. We aim to initiate larges insightful studies in the future based on the knowledge gained from this exploratory study. This project aims to uncover residual cardiovascular disease risks in PWH through a retrospective case-control study of 124 plasma samples, offering strategies for clinical intervention to benefit both PWH and non-HIV populations. The findings will broaden our understanding of cardiovascular risks in other systemic, diseases like sickle cell anemia.