Basic and Translational Mechanisms of Alloimmunization to RBC Transfusion. Project 2

红细胞输注同种免疫的基本和转化机制。

• 批准号: 10711669
• 负责人: CHANCE MARION JOHN LUCKEY
• 金额: $ 39.11万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-10 至 2028-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10711669
• 关键词: ADORA1 gene; ADORA2B gene; ATP Receptors; Address; Adenosine; Allogenic; Alloimmunization; Alternative Therapies; Antibodies; Antibody Formation; Antibody Response; Antigen-Antibody Complex; Antigens; Autoantigens; Autoimmunity; Automobile Driving; B-Cell Activation; B-Lymphocytes; Binding; Biological Markers; Cell Surface Proteins; Cell physiology; Chronic; Circulation; Clinical; Clinical Trials; Cyclic AMP; Data; Development; Endothelial Cells; Engineering; Equilibrium; Erythropoietin; Event; Exposure to; Future; Genetic Polymorphism; Human; Hypoxia; Immunoglobulin Class Switching; Immunoglobulin G; Immunosuppressive Agents; Infection; Insulin-Dependent Diabetes Mellitus; Isoantibodies; Mediating; Molecular; Morbidity - disease rate; Multiple Sclerosis; Patients; Phenotype; Plasmablast; Play; Polymers; Production; Publishing; Purinergic P1 Receptors; Purines; Purinoceptor; Research; Resources; Role; Sickle Cell Anemia; Signal Pathway; Signal Transduction; Source; Structure of germinal center of lymph node; TLR7 gene; Testing; Transfusion; Vaccination; clinically relevant; ecto-nucleotidase; extracellular; gain of function; high risk; hydroxyurea; loss of function; model design; mortality; mouse model; novel; patient population; patient subsets; pharmacologic; polymerization; prevent; responders and non-responders; response; side effect; small molecule; synergism; theories; therapeutic target; transfusion medicine; virtual

RBC alloimmunization occurs when patients make antibodies to foreign antigens expressed on allogenic donor RBCs, and remains a significant cause of morbidity and mortality among chronically transfused patients. Though the vast majority of RBC transfusions express foreign antigens, only a subset of transfused patients will make alloantibodies. Indeed, patients tend to stratify into those who make multiple alloantibodies (responders) and those who never make an alloantibody despite multiple transfusions (non-responders). However, the molecular factors that regulate responder vs. non-responder status are poorly defined. RBCs have long been known to secrete of ATP and regulate endothelial cell function via resultant purinergic signaling, but the impact of purinergic signaling on RBC alloimmunization has not been previously addressed. We hypothesize that RBC driven purinergic signaling tends to suppress the antibody response to transfused RBCs, and further that inherent differences in purinergic signaling sensitivities among patients can impact their responder status. Using a mouse model of RBC alloimmunization, our preliminary data demonstrate that multiple different steps in the purinergic signaling pathway (P2X7R, CD73, and ADORA2b) do indeed regulate anti-RBC alloantibody production. This proposal sets out to determine the exact cellular and molecular mechanisms by which purinergic signaling regulates RBC alloimmunization, and further determine whether the known gain and loss of function polymorphisms of purinergic receptors can dictate whether a given patient will make anti-RBC IgG alloantibodies. Specifically, Aim1 of our proposal will test the hypothesis that B cell binding to transfused RBCs induces PANX1 mediated ATP secretion, and this extracellular ATP drives P2X7R activation. We further hypothesize that P2X7R activation suppresses IgG class-switching and germinal center formation by inducing ectodomain shedding of key B cell surface proteins. Aim2 of our proposal will test the hypothesis that CD73 expression on B cells regulates the balance of AMP and Adenosine signaling on responding B cells, ultimately altering B cells responses by regulating intracellular cyclic-AMP signaling. Finally, Aim3 of this proposal will test the hypothesis that known polymorphisms in the P2X7R, ADORA1 and ADORA2b genes can account for some of the phenotypic differences observed among responder and non- responder patient populations. Synergy between projects comes from crosstalk between our focus on purinergic signaling and (a) the known interactions between P2X7R signaling and immune complex signaling through TLR7 and TLR9 (Project 1), (b) the fact that P2X7R is highly expresses on RBC precursors but decreases as RBCs mature (Project 3), and (c) the known enhancement of soluble CD73 and increased levels of ATP, ADP, AMP and Adenosine in patients with sickle cell disease (Project 4).

当患者针对同种异体供体上表达的外来抗原产生抗体时，就会发生红细胞同种免疫 红细胞仍然是长期输血患者发病和死亡的重要原因。 尽管绝大多数红细胞输血表达外源抗原，但只有一小部分输血患者 将产生同种抗体。事实上，患者往往分为产生多种同种抗体的患者 （有反应者）和尽管多次输血但从未产生同种抗体的人（无反应者）。 然而，调节应答者与非应答者状态的分子因素尚不清楚。红细胞 长期以来人们就知道它能分泌 ATP 并通过产生的嘌呤能调节内皮细胞功能 信号传导，但嘌呤能信号传导对红细胞同种免疫的影响此前尚未得到解决。 我们假设红细胞驱动的嘌呤能信号倾向于抑制抗体对输血的反应 红细胞，以及患者之间嘌呤能信号敏感性的固有差异可能会影响他们的 响应者状态。使用红细胞同种免疫小鼠模型，我们的初步数据表明 嘌呤能信号通路（P2X7R、CD73 和 ADORA2b）中的多个不同步骤确实调节 抗红细胞同种抗体的产生。该提案旨在确定确切的细胞和分子 嘌呤信号调节红细胞同种免疫的机制，并进一步确定是否 已知的嘌呤能受体功能多态性的获得和丧失可以决定特定患者是否会 制备抗红细胞 IgG 同种抗体。具体来说，我们提案的目标 1 将测试 B 细胞结合的假设 输注红细胞诱导 PANX1 介导的 ATP 分泌，这种细胞外 ATP 驱动 P2X7R 激活。我们进一步假设 P2X7R 激活抑制 IgG 类别转换和生发中心 通过诱导关键 B 细胞表面蛋白的胞外域脱落而形成。我们提案的目标 2 将测试 假设 B 细胞上的 CD73 表达调节 AMP 和腺苷信号传导的平衡 响应 B 细胞，最终通过调节细胞内环 AMP 信号传导来改变 B 细胞反应。 最后，该提案的 Aim3 将检验以下假设：P2X7R、ADORA1 和 P2X7R 中已知的多态性 ADORA2b 基因可以解释在应答者和非应答者之间观察到的一些表型差异。 有反应的患者群体。项目之间的协同来自于我们关注的领域之间的串扰 嘌呤能信号传导以及 (a) P2X7R 信号传导和免疫复合物信号传导之间已知的相互作用 通过 TLR7 和 TLR9（项目 1），(b) P2X7R 在红细胞前体上高度表达，但 随着红细胞成熟而减少（项目 3），以及 (c) 已知的可溶性 CD73 增强和水平增加 镰状细胞病患者的 ATP、ADP、AMP 和腺苷（项目 4）。