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CME Evaluation

Oral Communication Session

Modulators of Coagulation and von Willebrand Factor

Session: Functional regulation of natural anticoagulants

OC 76.5 - Protein S enhances the phagocytosis of phosphatidylserine-positive procoagulant erythrocyte ghosts in sickle cell disease

Wednesday, June 26, 2024
11:15 – 11:30 ICT
Room: 210 A-D

    Presenting Author(s)

  • Claire Auditeau, PharmD

    PharmD, PhD Student
    Hémostase Inflammation Thrombose (HITh) UMR-S1176 INSERM Université Paris-Saclay Le Kremlin-Bicêtre France
    Kremlin-Bicêtre, Ile-de-France, France

    • Co-Author(s)

  • AF

    Aurélie Fricot-Monsinjon

    Research engineer
    Université Paris Cité and Université des Antilles, Inserm, Biologie Tissulaire du Globule Rouge, Paris, France
    Paris, Ile-de-France, France

  • RG

    Raphaël Gauthier

    Assistant research ingeneer
    Université Paris Cité and Université des Antilles, Inserm, Biologie Tissulaire du Globule Rouge, Paris, France.
    Paris, Ile-de-France, France

  • ZC

    Zeynep Cacan

    Student trainee
    Université Paris Cité and Université des Antilles, Inserm, Biologie Tissulaire du Globule Rouge, Paris, France.
    Paris, Ile-de-France, France

  • AB

    Alain Brisson

    Professor
    UMR-CBMN, CNRS-Université de Bordeaux-IPB, 33600 Pessac, France.
    Paris, Ile-de-France, France

  • CG

    Céline Gounou

    Research ingeneer
    UMR-CBMN, CNRS-Université de Bordeaux-IPB, 33600 Pessac, France.
    Paris, Ile-de-France, France

  • LJ

    Laure Joseph

    Haematologist
    Department of Biotherapy, French National Sickle Cell Disease Referral Center, Hôpital Necker, Assistance-Publique Hôpitaux de Paris, Paris, France
    Paris, Ile-de-France, France

  • SM

    Sandra Manceau

    Project manager
    Department of Biotherapy, French National Sickle Cell Disease Referral Center, Hôpital Necker, Assistance-Publique Hôpitaux de Paris, Paris, France
    Paris, Ile-de-France, France

  • MK

    Mariem Khamari

    Laboratory technician
    Hémostase, Inflammation, Thrombose (HITh), UMR-S1176, INSERM, Université Paris-Saclay, Le Kremlin-Bicêtre, France.
    Le Kremlin Bicêtre, Ile-de-France, France

  • Sm

    Sophie moog

    Research ingeneer
    Hémostase, Inflammation, Thrombose (HITh), UMR-S1176, INSERM, Université Paris-Saclay, Le Kremlin-Bicêtre, France
    Le Kremlin Bicêtre, Ile-de-France, France

  • PB

    Pierre Buffet

    Professor
    Université Paris Cité and Université des Antilles, Inserm, Biologie Tissulaire du Globule Rouge, Paris, France,
    Paris, Ile-de-France, France

  • Delphine Borgel

    Professor
    Hémostase Inflammation Thrombose (HITh) UMR-S1176 INSERM Université Paris-Saclay Le Kremlin-Bicêtre France
    Paris, Ile-de-France, France

  • FS

    François Saller

    Associate Professor
    INSERM U1176, Université Paris Saclay, Le Kremlin-Bicêtre, France
    Le Kremlin-Bicêtre, Ile-de-France, France

  • CR

    Camille Roussel

    Researcher
    Université Paris Cité and Université des Antilles, Inserm, Biologie Tissulaire du Globule Rouge, Paris, France
    Paris, Ile-de-France, France

Background: Protein S (ProS) enhances the phagocytosis of apoptotic cells exposing phosphatidylserine (PdSer), by activating MerTK on macrophages. Red blood cells (RBC) of sickle cell disease (SCD) patients expose more PdSer than control RBC, especially erythrocyte ghosts (eryghosts) ie RBC lacking their hemoglobin content, and ProS was detected on SCD RBC.

Aims: We aimed to investigate the role of ProS in the phagocytosis of PdSer-exposing RBC in SCD.

Methods: Control RBC treated with ionomycin (inducing PdSer exposure), intact SCD RBC, and SCD eryghosts (isolated from plasma) were fluorescently labeled. They were added to THP-1-derived macrophages in the presence or absence of ProS and a MerTK inhibitor. The proportion of fluorescent THP-1, thus having phagocytosed RBC, was quantified by flow cytometry. Eryghosts were quantified in plasma by flow cytometry, and their procoagulant properties were assessed by thrombin and fibrin generation assays.

Results: A high proportion of ionomycin-treated RBC expressed PdSer (76.4 ± 21.7%, n=41) and ProS enhanced their phagocytosis from 20.8 ± 9.6 to 30.0± 9.67 % (n=21, p< 0.01). In contrast, PdSer expression was low in SCD RBC (1.2 ± 1.9%, n=18), and their phagocytosis was not modified by ProS (5.9 ± 4.3 vs 5.4±3.6%, n=10, p>0.99). The plasma concentration of eryghosts was 28.7-fold higher in SCD patients (n=53) than in controls (n=8). A high proportion of eryghosts exposed PdSer (76.4 ± 22.8%, n=18) and dose-dependently increased thrombin generation and fibrin formation (Fig1). ProS significantly increased their phagocytosis from 3.3 ± 4.8 to 8.2 ± 8.5% (n=17 p< 0.01), which was blocked by a MerTK inhibitor (Fig2).

Conclusion(s): As for nucleated cells, ProS enhances phagocytosis of PdSer-exposing RBC by activating MerTK. We could not confirm an increased PdSer-exposure on intact SCD RBC but found that a significant population of procoagulant PdSer-exposing eryghosts circulates in SCD patients. ProS enhances their phagocytosis while sparing intact SCD RBC.