P2Y12–P-selectin-mediated platelet activation in a murine model of dengue-associated thrombocytopenia

Background Dengue virus (DENV) infection frequently leads to thrombocytopenia, a hallmark of severe disease. However, the underlying mechanisms remain incompletely defined. Therefore, this study aimed to investigate the mechanisms underlying dengue-associated thrombocytopenia in a murine model, with a focus on defective thrombopoiesis and platelet activation. Methods Using a murine model that recapitulates key haematological and inflammatory features of human dengue, we investigated the impact of DENV infection on megakaryopoiesis, platelet activation, and thromboinflammatory responses. Bone marrow cellularity, megakaryocyte integrity, circulating cytokines and chemokines, platelet activation markers, and vascular injury were assessed. Pharmacological inhibition of P-selectin and blockade of the P2Y12 receptor with clopidogrel were used to evaluate the contribution of platelet activation pathways. Findings DENV infection impaired megakaryopoiesis, inducing necrotic loss of bone marrow megakaryocytes and leukocytes as early as day 3 post-infection, accompanied by bone marrow aplasia and a compensatory increase in thrombopoietin levels. Systemically, infection triggered P-selectin-dependent platelet activation and platelet-leucocyte aggregate formation, alongside elevated circulating chemokines (CXCL4, CCL5, and CXCL1), vascular leakage in the liver and lungs, and fibrin deposition in pulmonary tissue, consistent with enhanced thromboinflammation. Pharmacological blockade of P-selectin or inhibition of P2Y12 signalling restored platelet counts, preserved megakaryocyte numbers, and attenuated systemic inflammatory responses. Interpretation These findings indicate that DENV-induced thrombocytopenia arises from the combined effects of impaired megakaryopoiesis and platelet hyperactivation, highlighting platelet activation pathways as potential therapeutic targets for dengue-associated thromboinflammatory complications. Funding This work was supported by CNPq, FAPEMIG, Instituto Serrapilheira, and the ASH Global Research Award (465425/2014-3; 408527/2024-2; 163937/2022-2; 25036/2014-3; RED-00202-22 29568-1; APQ-04650-23 and APQ-02618 23).