Novel strategies to prevent FcgRIIA-dependent platelet activation and thrombosis

预防 FcgRIIA 依赖性血小板活化和血栓形成的新策略

• 批准号: 8501660
• 负责人: Wolfgang Bergmeier
• 金额: $ 35.94万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-20 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8501660
• 关键词: 1,2-diacylglycerol; 1-Phosphatidylinositol 3-Kinase; ADP Receptors; Agonist; Animal Model; Antibodies; Blood Platelet Disorders; Blood Platelets; Calcium; Clinical; Collagen; Cytoplasmic Granules; Data; Development; Diglycerides; Disease; Fc Receptor; Feedback; G-Protein-Coupled Receptors; Generations; Goals; Guanosine Triphosphate Phosphohydrolases; Hematological Disease; Hemorrhage; Hemostatic function; Heparin; Human; ITAM; Immune; Integrins; Knockout Mice; Link; Mediating; Minor; Modeling; Molecular; Morbidity - disease rate; Mus; Pathogenesis; Pathologic; Pathway interactions; Patients; Phospholipase C; Phosphorylation; Phosphotransferases; Physiological; Platelet Activation; Platelet aggregation; Play; Prevention; Protein Isoforms; Protein Tyrosine Kinase; Regulation; Research; Risk; Role; Safety; Second Messenger Systems; Signal Pathway; Signal Transduction; Signaling Molecule; Surface; Syndrome; Testing; Therapeutic; Thrombin; Thrombocytopenia; Thrombosis; Thromboxane A2; Thromboxanes; Transgenic Mice; Work; design; improved; inhibitor/antagonist; mortality; mouse model; novel; novel strategies; novel therapeutics; pre-clinical; prevent; receptor; receptor coupling; release of sequestered calcium ion into cytoplasm; second messenger; sensor; therapeutic target

DESCRIPTION (provided by applicant): Activation of the platelet Fc receptor, Fc?RIIA, is central to the pathogenesis of several immune- mediated thrombocytopenia and thrombosis (ITT) syndromes, including heparin-induced thrombocytopenia/thrombosis. One of the barriers to successful treatment of these thrombotic syndromes is that therapeutic targeting of platelet activation pathways to prevent thrombosis is either not effective or comes with an inherent risk of bleeding complications. The purpose of this proposal is a) to identify critical signaling molecules, which preferentially contribute to Fc?RIIA- mediated platelet activation and b) to develop therapeutic anti-platelet strategies to prevent pathologic thrombosis in ITT while minimizing bleeding complications. Our preliminary studies identify the tyrosine kinase Syk, the Ser/Thr kinase Akt, and the Ca2+ sensor CalDAG-GEFI as promising new targets for antiplatelet therapy in the setting of ITT. Downstream of ITAM-coupled receptors like Fc?RIIA, Syk is important for the activation of phospholipase C?2 and thus the generation of the second messengers Ca2+ and diacylglycerol. CalDAG-GEFI links an increase in intracellular Ca2+ to the signaling pathways regulating integrin activation, thromboxane generation, and granule release. Preliminary studies on Akt demonstrate that it is important for Fc?RIIA-induced calcium flux and integrin activation, thus linking it to Syk and CalDAG-GEFI. Preliminary results as well as work by us and others further demonstrate that Syk, CalDAG- GEFI, and Akt are particularly important for Fc?RIIA/ITAM-mediated platelet activation. With the proposed studies, we will improve our understanding of the molecular mechanisms by which CalDAG-GEFI (aim 1) and Akt (aim 2) contribute to Fc?RIIA-mediated platelet activation. In aim 3, we will validate Syk and Akt and explore CalDAG-GEFI as therapeutic targets in ITT. The safety and efficacy of pharmacologic inhibition of Syk and Akt for the treatment and prevention of ITT will be tested in our established mouse models. The utility of CalDAG-GEFI or Akt2 as therapeutic targets for the treatment of ITT will be evaluated in crosses between mice transgenic for the human Fc?RIIA and mice knockout for CalDAG-GEFI or Akt2. The successful completion of this proposal will accelerate the rational design of novel therapeutics for immune-mediated platelet disorders.

描述（由申请人提供）：血小板FC受体FC？riia的激活是几种免疫介导的血小板减少症和血栓形成（ITT）综合征的发病机理，包括肝素诱导的血小板细胞培养症/血栓形成。成功治疗这些血小板综合征的障碍之一是，治疗性血小板激活途径预防血栓形成是无效的，要么具有出血并发症的固有风险。该提案的目的是a）确定关键的信号分子，哪些优先促进了FC？riiA介导的血小板激活，b）开发治疗性抗静脉策略，以防止ITT中的病理性血栓形成，同时最大程度地减少出血并发症。我们的初步研究将酪氨酸激酶SYK，SER/THR激酶AKT和CA2+传感器Caldag-Gefi视为ITT环境中抗血小板治疗的有希望的新靶标。 ITAM耦合受体（例如Fc？riia）的下游，Syk对于激活磷脂酶C 2？2很重要，从而产生了第二个使者Ca2+和二酰基甘油。 Caldag-Gefi将细胞内Ca2+的增加与调节整合素激活，血栓烷产生和颗粒释放的信号通路联系起来。对AKT的初步研究表明，它对于Fc？riiA诱导的钙通量和整合素激活很重要，从而将其与Syk和Caldag-Gefi联系起来。初步结果以及我们和其他人的工作进一步表明，Syk，Caldaggefi和Akt对于FC？RIIA/ITAM介导的血小板激活尤为重要。通过拟议的研究，我们将提高对Caldag-Gefi（AIM 1）和AKT（AIM 2）促进FC riiA介导的血小板激活的分子机制的理解。在AIM 3中，我们将验证SYK和AKT并探索Caldag-Gefi作为ITT的治疗靶标。 SYK和AKT的药理学抑制对ITT治疗和预防的安全性和功效将在我们已建立的小鼠模型中进行测试。 Caldag-Gefi或Akt2作为治疗ITT治疗的效用将在人类FC？RIIA的小鼠转基因和Caldag-Gefi或Akt2的小鼠敲除小鼠之间评估。该提案的成功完成将加速免疫介导的血小板疾病的新型治疗方法的合理设计。