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).

当患者对异体供者表达的异种抗原产生抗体时，就会发生红细胞同种免疫。 红细胞，并且仍然是长期输血患者发病和死亡的重要原因。 尽管绝大多数输血的红细胞都表达外来抗原，但只有一小部分输血患者 会产生同种异体抗体。事实上，患者倾向于分成制造多种同种异体抗体的患者。 (应答者)和那些尽管多次输血但从未产生同种抗体的人(非应答者)。 然而，调节应答者和非应答者状态的分子因素还不清楚。红细胞 早就知道通过合成的嘌呤能分泌三磷酸腺苷并调节内皮细胞的功能 信号转导，但嘌呤能信号转导对红细胞同种异体免疫的影响以前还没有被解决。 我们假设，红细胞驱动的嘌呤能信号往往会抑制对输血的抗体反应 此外，患者对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RBC同种免疫的小鼠模型，我们的初步数据表明 嘌呤能信号通路中的多个不同步骤(P2X7R、CD73和ADORA2b)确实可以调节 抗RBC同种异体抗体的产生。这项提议旨在确定准确的细胞和分子 嘌呤能信号调节红细胞同种异体免疫的机制，并进一步确定 已知的嘌呤能受体功能获得和功能丧失的多态可以决定特定患者是否会 制备抗红细胞免疫球蛋白同种异体抗体。具体地说，我们建议的Aim1将测试B细胞结合的假设 输注红细胞可诱导Panx1介导的ATP分泌，这种胞外ATP驱动P2X7R 激活。我们进一步假设，P2X7R激活抑制了免疫球蛋白G类转换和生发中心 通过诱导关键的B细胞表面蛋白的胞外区脱落而形成。我们提案的AIM2将测试 B细胞CD73表达调节AMP和腺苷信号平衡的假说 反应B细胞，最终通过调节细胞内的环磷酸腺苷信号改变B细胞的反应。 最后，该提案的Aim3将检验这样一个假设，即已知的P2X7R、ADORA1和 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 应答者患者群体。项目之间的协同来自于我们专注于 嘌呤能信号和(A)已知的P2X7R信号和免疫复合物信号之间的相互作用 通过TLR7和TLR9(项目1)，(B)P2X7R在红细胞前体上高度表达的事实，但 随着红细胞的成熟而减少(项目3)，以及(C)已知的可溶性CD73的增加和水平的增加 镰状细胞病患者的ATP、ADP、AMP和腺苷的变化(项目4)。