Ph.D. Candidate University of Rochester Medical Center, United States
Introduction/Rationale: People living with HIV (PLWH) are more susceptible to atherosclerosis (AS). Here, we examine the functional consequences of platelet-monocyte complexes (PMCs), which are elevated in PLWH and are hypothesized to contribute to HIV-associated comorbidities.
Methods: We performed single-cell RNA sequencing (scRNAseq) of monocytes isolated from age-, sex-, and cardiovascular risk score-matched participants categorized based on HIV and early AS status (n=8 per group). Monocytes and platelets were cocultured ex vivo ± LPS (to simulate chronic inflammation) and analyzed at multiple time points as PMCs (24 hours) and PMC-derived macrophages (MΦs, six days) via bulk RNA sequencing/RT-qPCR, ELISA, and flow cytometry. PMCs were cocultured with primary human endothelial cells (ECs) between three and six days of macrophage differentiation to assess endothelial to mesenchymal transition (EndMT) via RT-qPCR and ELISA.
Results: scRNAseq PMCs in PLWH and AS had increased TGF-β/IL-10 signaling compared to either PLWH or people living with AS (PLWAS) alone. Ex-vivo PMCs upregulated expression of genes involved in TGF-β signaling and IL-10 expression at both the monocyte and MΦ developmental states. LPS stimulation increased IL-10 and TGF-β secretion and reduced TNF-α levels in culture supernatants. PMC-derived MΦs increased expression of costimulatory molecules CD86 and CD80. When cultured with primary ECs, PMC-derived MΦs reduced Pecam1 and Cdh5 and increased S100a4 expression. CCL2 and IL-6 were elevated in PMC-derived MΦ-EC cocultures. LPS stimulation of cocultures increased expression of adhesion molecules Icam1 and Vcam.
Conclusion: Platelet interactions underscore monocyte-MΦ differentiation that promotes EndMT via TGF-β and IL-10, suggesting a pro-AS role of these factors in early disease. Enhanced TGF-β/IL-10 expression in PMCs of PLWH and AS suggests an increased relevance of this pathology in these individuals and defines a mechanistic link between aberrant platelet activation, PMC formation, and AS in PLWH.
