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Platelet Immunometabolic Reprogramming Links Immune Cell Crosstalk to Thromboinflammation in Philadelphia-negative Myeloproliferative Neoplasms

Year: 2026

Type: article

Abstract: Backgroun and aim Myeloproliferative neoplasms (MPN) are hematological malignancies driven by JAK2, CALR, or MPL mutations. Chronic inflammation and increased thrombotic risk are major MPN features. Although frequent, thrombocytosis poorly correlates with thrombosis rate in MPN. Qualitative platelet alterations seem to influence more significantly thrombotic complications than platelet count. Therefore, we investigated platelet-leukocyte interactions and platelet lipidomic profiles in controls (n = 25) and patients with polycythemia vera (PV, n = 25), essential thrombocythemia (ET, n = 25), and primary myelofibrosis (MF, n = 25). Methods Purified platelets were isolated from platelet-rich plasma by sequential centrifugation (200 × g, 15 min and 420 × g, 10 min, respectively) and submitted to high-resolution LC-MS/MS lipidomics. Platelet-monocyte, platelet-neutrophil, and platelet-T or B lymphocyte aggregates were identified in whole blood by flow cytometry as leukocyte populations expressing the platelet marker CD41a after antibody staining, erythrocyte lysis, and fixation. Bioactive lipid signatures were analyzed according to treatment status, previous cardiovascular events, and pharmacological inhibition of COX and LOX pathways. Results MPN patients exhibited increased spontaneous formation of platelet-monocyte, -neutrophil, and -lymphocyte aggregates compared to controls (p < 0.0001). Platelet-bound monocytes showed higher expression of tissue factor (CD42; p < 0.0001) and CD36 (p < 0.0001), indicating a platelet-monocyte thromboinflammatory and pro-coagulant cooperation. Untargeted lipidomics revealed a depletion of key lipid substrates, including arachidonic acid, DGLA, EPA, DHA, LPC, and GPC, consistent with lipid consumption for activation. Despite substrate depletion, inflammatory omega-6-derived lipid mediators were preserved, revealing a disease-specific remodeling of the COX, LOX, and CYP pathways. Targeted lipidomics mainly identified that 5-HETE levels were increased in PV (p = 0.0008), ET (p < 0.0001), and MF (p = 0.0135) platelets. PGE₂ was elevated in ET (p < 0.0001) and MF (p = 0.0038), whereas PGD₂ was increased in MF versus controls (p = 0.0230) and PV (p = 0.0014). In vitro inhibition with indomethacin or MK-591 showed that LOX inhibition more effectively decreased BLTR-1 expression and pro-coagulant platelet phenotype, suggesting a central role for the LOX/5-HETE axis and revealing a persistent residual COX/eicosanoid activity. Sphingolipid remodeling was disease-specific, with depletion of ceramides in PV and enrichment of multiple sphingolipid subclasses in ET. These signatures persisted despite cytoreductive and antiplatelet therapy, while patients with previous cardiovascular events exhibited increased platelet sphingolipid abundance. Conclusions MPN platelets present a sustained immunometabolic dysfunction, characterized by enhanced interaction with leukocytes and reprogrammed lipid metabolism. The persistence of these alterations despite hydroxycarbamide and acetylsalicylic acid therapy, together with evidence of residual COX pathway activity and a dominant LOX/5-HETE axis, indicates that current standard therapies do not fully normalize platelet function, which seem to be reprogrammed. These findings identify platelet lipid metabolism as a mechanistic driver of thromboinflammation and a promising source of therapeutic targets to treat MPN.

Source: Hematology Transfusion and Cell Therapy

DOI: 10.1016/j.htct.2026.107530