Administrative Supplement: Ayiesha Barnes

行政补充：Ayiesha Barnes

基本信息

批准号：
9810534
负责人：
Gowthami M Arepally
金额：
$ 7.84万
依托单位：
DUKE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2018
资助国家：
美国
起止时间：
2018-01-15 至 2021-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9810534
关键词：
Administrative Supplement Allergic Disease Allergic Reaction Antibodies Antibody Formation Anticoagulants Antigens Autoantibodies Autoantigens Autoimmune Diseases B-Lymphocytes Binding Biological Assay Blood Blood Circulation Blood Platelets Carbohydrates Charge Communicable Diseases Complement Complement 3d Receptors Complement Activation Complex Data Deposition Development Disease Dose Event Follicular Dendritic Cells Funding Grant Heparin Heparin Binding Humoral Immunities Hypersensitivity Immune Immune response Immunoassay In Vitro Incubated Individual Knowledge Lectin Leukocytes Life Link Mannose Binding Lectin Mediating Mus Pathogenesis Pathway interactions Patients Pharmaceutical Preparations Plasma Play Polysaccharides Predisposition Proteins Proteome Receptors, Antigen, B-Cell Regulation Role Sampling Signal Transduction Structure Testing Thrombosis Time Transgenic Organisms Variant adaptive immunity antigen binding base ficolin ficolin-beta heparin-induced thrombocytopenia immune activation immunogenic immunogenicity in vivo novel recruit response sample fixation seroconversion

项目摘要

ABSTRACT Heparin-induced thrombocytopenia (HIT) is a life-threatening immune-mediated thrombotic disorder caused by antibodies to PF4/heparin complexes. The immune response is common and yet little is understood about its occurrence. In the last funding period, we made fundamental observations related to early events surrounding the host’s encounter with the PF4/heparin antigenic complex. Specifically, we showed: 1) preferential binding of PF4/heparin to circulating B-cells, compared with other leukocytes or platelets, 2) heparin-dependent binding of PF4/heparin to B-cells in patients receiving heparin, 3) complement fixation by PF4/heparin antigen, 4) complement-mediated PF4/heparin binding to circulating B-cells in patients receiving heparin, and 5) binding of complement-coated antigen to B-cells via complement receptor 2 (CR2/ CD21). In the following aims, we will test the hypothesis that complement activation by PF4/heparin complexes and deposition of antigen on B-cells via CD21 is essential for development of HIT autoantibodies. Specific Aim 1: Mechanism of complement activation by PF4/heparin complexes. In preliminary data, we show that mannose-binding lectin and ficolin-2 bind PF4/heparin complexes. Based on these findings, we will test the hypothesis that PF4/heparin complexes activate complement via the lectin pathway. We will define the structural basis of PF4/heparin-lectin interactions, study functional interactions of lectins with PF4/heparin complexes, and examine the role of complement inhibition in HIT. Specific Aim 2: Cellular consequences of CD21 engagement by PF4/heparin and complement. Binding of complement-coated antigen to CD21 augments humoral immunity by 103 to 104 fold. We hypothesize that binding of complement-coated multivalent PF4/heparin to the CD21 complex facilitates recruitment and signaling of antigen-specific B-cells. We will examine downstream signaling, activation and proliferation of cognate and non-cognate B-cells, perform in vivo studies in mice with a fixed B-cell receptor and characterize the contribution of CD21-expressing follicular dendritic cells to Ab formation. Specific Aim 3: Examine host predictors of PF4/heparin seroconversion. Complement-coated antigen can be detected on B-cells in some, but not all, patients receiving heparin therapy. Using a novel C3 capture immunoassay, we also show significant donor to donor variation in healthy donor plasma incubated with a fixed dose of PF4/heparin. Based on these observations, we will examine host susceptibility to anti- PF4/heparin seroconversions by characterizing the complement proteome and using antigen-positive B-cells as a marker for seroconversions in heparinized patients. By defining the cellular pathways that initiate formation of PF4/heparin Abs, we hope to uncover mechanisms relevant to the immunogenicity of other auto- or exogenous antigens.

抽象的肝素诱导的血小板减少症（HIT）是一种危及生命的免疫介导的血栓性疾病，由以下原因引起： PF4/肝素复合物的抗体免疫反应很常见，但对其了解甚少。在上一个资助期间，我们对周围的早期事件进行了基本观察。具体来说，我们展示了宿主与 PF4/肝素抗原复合物的相遇：1) 优先结合。与其他白细胞或血小板相比，PF4/肝素对循环 B 细胞的影响，2) 肝素依赖性接受肝素的患者中 PF4/肝素与 B 细胞的结合，3) PF4/肝素抗原的补体固定， 4) 补体介导的 PF4/肝素与接受肝素的患者的循环 B 细胞结合，以及 5) 结合通过补体受体 2 (CR2/CD21) 将补体包被的抗原转移到 B 细胞上。检验以下假设：PF4/肝素复合物激活补体并在 B 细胞上沉积抗原通过 CD21 对于 HIT 自身抗体的开发至关重要。具体目标 1：补体机制。 PF4/肝素复合物的激活在初步数据中，我们表明甘露糖结合凝集素和 ficolin-2。结合 PF4/肝素复合物基于这些发现，我们将检验 PF4/肝素复合物的假设。通过凝集素途径激活补体我们将定义 PF4/肝素凝集素的结构基础。相互作用，研究凝集素与 PF4/肝素复合物的功能相互作用，并检查具体目标 2：CD21 参与的细胞补体后果 PF4/肝素和补体包被的抗原与 CD21 的结合增强体液免疫。我们捕获了补体包被的多价 PF4/肝素与 CD21 的结合。复合物促进抗原特异性 B 细胞的募集和信号传导。我们将检查下游。同源和非同源 B 细胞的信号传导、激活和增殖，在小鼠中进行体内研究固定 B 细胞受体并表征表达 CD21 的滤泡树突状细胞对 Ab 的贡献具体目标 3：检查 PF4/肝素血清转化的宿主预测因子。使用新型 C3 可以在部分（但不是全部）接受肝素治疗的患者的 B 细胞上检测到抗原。捕获免疫分析，我们还显示了在孵化的健康供体血浆中显着的供体差异根据这些观察结果，我们将检查宿主对抗-PF4/肝素的敏感性。通过表征补体蛋白质组并使用抗原阳性 B 细胞进行 PF4/肝素血清转化作为肝素化患者血清转化的标志物通过定义启动的细胞途径。 PF4/肝素抗体的形成，我们希望揭示与其他自身免疫原性相关的机制或外源性抗原。