Hamostaseologie 2022; 42(S 01): S32-S37
DOI: 10.1055/s-0042-1758499
Abstracts

Investigations to Assess the Impact of Syk-Inhibition on Antibody-Mediated Desialylation: Novel Implications on Therapy for Immune Thrombocytopenia

Anurag Singh
1   Institute for Clinical and Experimental Transfusion Medicine (IKET), University Hospital of Tuebingen, Tuebingen, Germany
,
Filip Toma
1   Institute for Clinical and Experimental Transfusion Medicine (IKET), University Hospital of Tuebingen, Tuebingen, Germany
,
Karina Althaus
1   Institute for Clinical and Experimental Transfusion Medicine (IKET), University Hospital of Tuebingen, Tuebingen, Germany
2   Center for Clinical Transfusion Medicine ZKT GmbH, Tuebingen, Germany
,
Tamam Bakchoul
1   Institute for Clinical and Experimental Transfusion Medicine (IKET), University Hospital of Tuebingen, Tuebingen, Germany
2   Center for Clinical Transfusion Medicine ZKT GmbH, Tuebingen, Germany
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Immune thrombocytopenia (ITP) is an autoantibody-mediated bleeding disorder with an increased clearance of platelets and megakaryocyte dysfunction. Previously, we showed that antibody-induced desialylation plays a significant role in the pathophysiology of ITP, leading to impaired platelet adhesion and megakaryocyte differentiation via FcγRIIA.[1] In the current study, we aim to investigate whether spleen tyrosine kinase (Syk) inhibition can alter the platelet responses and desialylation, and improve the patient outcome in ITP. We aim to gain in-depth understanding of various aspects of Syk inhibition on human platelets, using a broad range of in vitro and ex vivo methods including flow cytometry, fluorescence microscopy, and calibrated automated thrombogram. To elucidate the role of FcyRIIA, anti-CD32 clone AT-10 was used followed by crosslinking with the secondary Fab2 antibody to stimulate the receptor. Activation of FcγRIIA resulted in a significant increase in platelet activation, apoptosis, and desialylation. Activated platelets were analyzed by CD62P and PAC1 expression and platelet apoptosis was determined as mitochondrial-transmembrane potential (Δψ) depolarization and phosphatidylserine externalization. Lectin binding to fluorescein-conjugated Ricinus communis agglutinin I was quantified to detect desialylation. Our data show that Syk inhibition can effectively alter antibody-mediated biological effects in ITP, which lead to platelet dysfunction via involvement of FcγRIIA. We were able to prevent antibody-mediated desialylation and impairment of platelet function, and platelet apoptosis in ITP via Syk inhibition. In ongoing studies, we explore the opportunity to restore impaired proplatelet formation by megakaryocytes with Syk inhibition and investigate the possibility of reverting desialylation in an established ex vivo model of thrombopoiesis. In summary, our data indicate that Syk inhibition might be a promising approach to prevent antibody-mediated platelet desialylation in ITP, and might serve as a potential therapeutic strategy to prevent patient complications during pathogenesis of ITP.



Publication History

Article published online:
26 October 2022

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  • Reference

  • 1 Marini I, Zlamal J, Faul C. et al. Autoantibody-mediated desialylation impairs human thrombopoiesis and platelet lifespan. Haematologica 2021; 106 (01) 196-207
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