Rational design and characterization of platelet factor 4 antagonists for the study of heparin-induced thrombocytopenia

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Rational design and characterization of platelet factor 4 antagonists for the study of heparin-induced thrombocytopenia. / Sachais, Bruce S; Rux, Ann H; Cines, Douglas B; Yarovoi, Serge V; Garner, Lee I; Watson, Stephen P; Hinds, Jillian L; Rux, John J; Watson, Steve.

In: Blood, Vol. 119, No. 25, 2012, p. 5955-62.

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Sachais, Bruce S ; Rux, Ann H ; Cines, Douglas B ; Yarovoi, Serge V ; Garner, Lee I ; Watson, Stephen P ; Hinds, Jillian L ; Rux, John J ; Watson, Steve. / Rational design and characterization of platelet factor 4 antagonists for the study of heparin-induced thrombocytopenia. In: Blood. 2012 ; Vol. 119, No. 25. pp. 5955-62.

Bibtex

@article{7760ea9fa70c41a3a07a832e9eff9fb2,
title = "Rational design and characterization of platelet factor 4 antagonists for the study of heparin-induced thrombocytopenia",
abstract = "Patients with heparin-induced thrombocytopenia (HIT) remain at risk for recurrent thromboembolic complications despite improvements in management. HIT is caused by antibodies that preferentially recognize ultralarge complexes (ULCs) of heparin and platelet factor 4 (PF4) tetramers. We demonstrated previously that a variant PF4(K50E) forms dimers but does not tetramerize or form ULCs. Here, we identified small molecules predicted to bind PF4 near the dimer-dimer interface and that interfere with PF4 tetramerization. Screening a library of small molecules in silico for binding at this site, we identified 4 compounds that inhibited tetramerization at micromolar concentrations, designated PF4 antagonists (PF4As). PF4As also inhibited formation of pathogenic ULCs, and 3 of these PF4As promoted the breakdown of preformed ULCs. To characterize the ability of PF4As to inhibit cellular activation, we developed a robust and reproducible assay that measures cellular activation by HIT antibodies via FcγRIIA using DT40 cells. PF4As inhibit FcγRIIA-dependent activation of DT40 cells by HIT antibodies as well as platelet activation, as measured by serotonin release. PF4As provide new tools to probe the pathophysiology of HIT. They also may provide insight into the development of novel, disease-specific therapeutics for the treatment of thromboembolic complications in HIT.",
author = "Sachais, {Bruce S} and Rux, {Ann H} and Cines, {Douglas B} and Yarovoi, {Serge V} and Garner, {Lee I} and Watson, {Stephen P} and Hinds, {Jillian L} and Rux, {John J} and Steve Watson",
year = "2012",
doi = "10.1182/blood-2012-01-406801",
language = "English",
volume = "119",
pages = "5955--62",
journal = "Blood",
issn = "0006-4971",
publisher = "American Society of Hematology",
number = "25",

}

RIS

TY - JOUR

T1 - Rational design and characterization of platelet factor 4 antagonists for the study of heparin-induced thrombocytopenia

AU - Sachais, Bruce S

AU - Rux, Ann H

AU - Cines, Douglas B

AU - Yarovoi, Serge V

AU - Garner, Lee I

AU - Watson, Stephen P

AU - Hinds, Jillian L

AU - Rux, John J

AU - Watson, Steve

PY - 2012

Y1 - 2012

N2 - Patients with heparin-induced thrombocytopenia (HIT) remain at risk for recurrent thromboembolic complications despite improvements in management. HIT is caused by antibodies that preferentially recognize ultralarge complexes (ULCs) of heparin and platelet factor 4 (PF4) tetramers. We demonstrated previously that a variant PF4(K50E) forms dimers but does not tetramerize or form ULCs. Here, we identified small molecules predicted to bind PF4 near the dimer-dimer interface and that interfere with PF4 tetramerization. Screening a library of small molecules in silico for binding at this site, we identified 4 compounds that inhibited tetramerization at micromolar concentrations, designated PF4 antagonists (PF4As). PF4As also inhibited formation of pathogenic ULCs, and 3 of these PF4As promoted the breakdown of preformed ULCs. To characterize the ability of PF4As to inhibit cellular activation, we developed a robust and reproducible assay that measures cellular activation by HIT antibodies via FcγRIIA using DT40 cells. PF4As inhibit FcγRIIA-dependent activation of DT40 cells by HIT antibodies as well as platelet activation, as measured by serotonin release. PF4As provide new tools to probe the pathophysiology of HIT. They also may provide insight into the development of novel, disease-specific therapeutics for the treatment of thromboembolic complications in HIT.

AB - Patients with heparin-induced thrombocytopenia (HIT) remain at risk for recurrent thromboembolic complications despite improvements in management. HIT is caused by antibodies that preferentially recognize ultralarge complexes (ULCs) of heparin and platelet factor 4 (PF4) tetramers. We demonstrated previously that a variant PF4(K50E) forms dimers but does not tetramerize or form ULCs. Here, we identified small molecules predicted to bind PF4 near the dimer-dimer interface and that interfere with PF4 tetramerization. Screening a library of small molecules in silico for binding at this site, we identified 4 compounds that inhibited tetramerization at micromolar concentrations, designated PF4 antagonists (PF4As). PF4As also inhibited formation of pathogenic ULCs, and 3 of these PF4As promoted the breakdown of preformed ULCs. To characterize the ability of PF4As to inhibit cellular activation, we developed a robust and reproducible assay that measures cellular activation by HIT antibodies via FcγRIIA using DT40 cells. PF4As inhibit FcγRIIA-dependent activation of DT40 cells by HIT antibodies as well as platelet activation, as measured by serotonin release. PF4As provide new tools to probe the pathophysiology of HIT. They also may provide insight into the development of novel, disease-specific therapeutics for the treatment of thromboembolic complications in HIT.

U2 - 10.1182/blood-2012-01-406801

DO - 10.1182/blood-2012-01-406801

M3 - Article

C2 - 22452981

VL - 119

SP - 5955

EP - 5962

JO - Blood

JF - Blood

SN - 0006-4971

IS - 25

ER -