Administrative Supplement: Ayiesha Barnes

行政补充：Ayiesha Barnes

• 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
• 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

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.

摘要 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， PF 4/肝素复合物的抗体。免疫反应是常见的，但很少有人了解其 发生。在上一个融资期，我们对围绕着 宿主与PF 4/肝素抗原复合物的接触具体来说，我们发现：1）优先结合 与其他白细胞或血小板相比，PF 4/肝素对循环B细胞的作用，2）肝素依赖性 在接受肝素的患者中PF 4/肝素与B细胞的结合，3）PF 4/肝素抗原的补体固定， 4)在接受肝素的患者中补体介导的PF 4/肝素与循环B细胞的结合，和5）结合 通过补体受体2（CR2/CD 21）将补体包被抗原与B细胞结合。在以下目标中，我们将 检验PF 4/肝素复合物激活补体并在B细胞上沉积抗原的假设 通过CD 21是HIT自身抗体的发展所必需的。具体目标1：补体机制 通过PF 4/肝素复合物活化。在初步数据中，我们表明甘露糖结合凝集素和纤维胶凝蛋白-2 结合PF 4/肝素复合物。基于这些发现，我们将检验PF 4/肝素复合物 通过凝集素途径激活补体。我们将定义PF 4/肝素-凝集素的结构基础 相互作用，研究凝集素与PF 4/肝素复合物的功能相互作用，并检查 HIT中的补体抑制。具体目标2：CD 21参与的细胞后果 PF 4/肝素和补体。补体包被抗原与CD 21结合增强体液免疫 103到104倍。我们假设补体包被的多价PF 4/肝素与CD 21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、活化和增殖，在具有 固定的B细胞受体，并表征表达CD 21的滤泡树突状细胞对Ab 阵具体目标3：检查PF 4/肝素血清转化的宿主预测因子。补体包被的 在接受肝素治疗的一些但不是全部患者的B细胞上可以检测到抗原。使用新型C3 捕获免疫测定，我们还显示了显着的供体到供体的变化，在健康供体血浆孵育 注射固定剂量的PF 4/肝素基于这些观察，我们将研究宿主对抗- 通过表征补体蛋白质组和使用抗原阳性B细胞的PF 4/肝素血清转化 作为肝素化患者血清转化的标志物。通过定义细胞通路， PF 4/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。