Th191 - Single-Cell Profiling of Circulating Monocytes Reveals Novel Platelet-Monocyte Complexes in HIV-Associated Atherosclerosis

Abstract Text: Individuals living with HIV (PLWH) have an increased risk of developing atherosclerosis (AS), even when receiving antiretroviral therapy (ART). This risk arises partly from monocytes, which release pro-inflammatory cytokines, drive immune activation, and contribute to thrombosis. Notably, persistent platelet and monocyte activation in HIV leads to intensified interactions between these two cell types, further promoting inflammatory cascades and immune dysregulation in monocytes. In this study, we profiled 138,487 monocytes at single-cell resolution across four groups (HIV, AS only, HIV-AS double positive, and control) to investigate the heterogeneity of circulating monocytes. Our analysis revealed eight distinct transcriptional subpopulations, including CD14, CD14-active, CD16, Intermediate, Intermediate-metabolic, Intermediate-interferon monocytes, as well as two novel subsets: platelet-monocyte complexes and NK/proinflammatory monocytes. Furthermore, we applied a novel Gene-Set Analysis approach, single-cell Pathway Score (scPS), developed by our group to estimate disease-relevant pathways and transcription factors uniquely dysregulated in HIV-associated AS. These findings were reinforced by mass spectrometry-based proteomics and co-culture experiments, highlighting the central role of platelet-monocyte complexes in platelet activation and chemokine-driven signaling. Overall, this study reveals previously uncharacterized monocyte subsets and molecular signatures, thereby providing new insights into the mechanisms linking HIV and atherosclerosis, and identifying potential avenues for targeted therapeutic intervention.