Circulating Platelets and Microvesicles Regulate Splenic T Cell Responses in Murine Atherosclerosis

Abstract

Atherosclerosis is a chronic inflammatory disease marked by the accumulation of lipid-laden plaques and immune cell infiltration within the arterial wall. Platelets and their derived microvesicles (PMVs) are recognized as critical modulators of T cell activation via direct contact and miRNA transfer, including miR-142-3p, a regulator of immune function and survival. The aim of this study was to investigate the immunomodulatory effects of platelets and MVs from healthy mice on splenic T cells in a murine model of advanced atherosclerosis. Platelets, MVs, and splenic T cells were isolated from two experimental groups: (1) C57BL/6J mice on standard chow for 12 weeks as the healthy control group (C) and (2) ApoE − / − mice fed a high-fat, high-cholesterol diet for 12 weeks, as the advanced atherosclerotic group (HFHC). T cells were stimulated in vitro and co-incubated with platelets or MVs from control mice for 3 days. Flow cytometry and qRT-PCR were used to assess activation markers, miR-142-3p levels, and gene expression. HFHC mice showed increased platelet counts, elevated P-selectin levels, and a fourfold increase in circulating MVs, along with enhanced platelet-T cell aggregation. Concomitantly, T cells from HFHC mice exhibited reduced activation (CD8⁺CD69⁺ and CD4⁺CD154⁺ subsets) and augmented IL-17 production, compared to control. At the molecular level, miR-142-3p was consistently reduced in plasma, platelets, and MVs from HFHC mice relative to controls, suggesting systemic depletion of this regulatory miRNA with disease progression. Consistent with this, co-incubation with control-derived platelets and MVs significantly elevated intracellular miR-142-3p in control T cells-an effect entirely absent in HFHC T cells. Finally, MV treatment differentially reprogrammed gene expression depending on the T cell origin: in control T cells, MVs upregulated Cxcl4, integrin αV, Bax, and Bcl2, whereas in HFHC T cells, they reduced integrin αV and increased TGF-β1 expression, pointing to divergent immunomodulatory programs. Our findings suggest that miR-142-3p may contribute to PMV-mediated modulation of T cell responses, but these effects are impaired under atherogenic conditions, highlighting a disrupted platelet-T cell communication axis in atherosclerosis.