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    Poster Networking

    Hemostatic Systems in Cancer, Inflammation and Immunity

    Poster Networking Session

    PB0715 - H3 alters the behavior of endothelial cells in vitro

    Monday, June 26, 2023
    18:30 – 19:30 ET
    Room: Exhibition
    Background: Neutrophil extracellular traps (NETs) consist of fibers of DNA-histone complexes and proteins, released by activated polynuclear cells. NETs are involved in bacterial infection, cardiovascular disease, autoimmunity, but also in cancer. Involvement of NETs in cancer increases the occurrence of thrombosis. Previously, we reported the influence of DNA on Fibrin clot structure [Ullah, ISTH 2021] and of histone-3 protein (H3) in peritoneal carcinomatosis patients, as well as its impact on plasma fibrinolysis [Mirshahi, ISTH 2022].

    Aims: To analyze the impact of Histone (H3) derived from NETS on the behavior of endothelial cells in vitro.

    Methods: 36 cancer patients with peritoneal carcinomatosis were enrolled from Pitie-Salpetriere hospital. Histones H3, H4 and DNA were quantified by ELISA in plasma. Viscoelasticity measurement was performed by Rheometer and clot elasticity was measured by ROTEM®. Clotting time (CT) and clot lyse time (CLT) were determined by CLA assay on a STA-R Max prototype [Fontaine, ISTH 2022]. Thrombin generation (TG) was measured on CAT®. Polynuclear cells were isolated from whole blood by ficoll and activated later by LPS. The impact of the plasmas on the behavior of endothelial cells (HMEC-1) was performed by the real-time proliferation method via xCelligence apparatus.

    Results: Circulating H3 levels in the 36 plasmas varied from 0.6 to 22.5ng/mL, (H3- < 1 ng/mL, H3+ ≥ 1 ng/mL). H3 did not correlate with H4 and DNA levels. Plasma H3 did not influence CT (H3+/H3- ratio=1.05) nor TG, unlike CLT which was prolonged (H3+/H3- ratio=1.46). Rheometric analysis showed that H3+ plasmas had significantly increased viscoelasticity of fibrin (H3+/H3- ratio = 2.2; p< 0.05). Moreover, H3+ patient plasma as well as purified H3 protein decreased cell growth of endothelial cells in vitro by the real-time proliferation method.

    Conclusion(s): H3 in cancer patients was associated with CLT resistance to fibrinolysis and increase in viscoelasticity. H3 modifies the behavior of vascular endothelial cells.