Transcriptional Control of Memory Responses to Red Blood Cell Alloimmunization

描述（由申请人提供）：红细胞同种异体免疫仍然是输血医学中常见的临床问题。同种抗体是溶血性输血反应的原因，导致大量发病率和偶尔死亡率。对于那些不幸产生多种同种抗体的患者，提供相容的RBC可能是时间和资源密集型的。在某些情况下，这可能导致无法找到其他挽救生命的治疗方法。尽管其临床重要性，我们的理解如何长寿的记忆红细胞同种抗体反应是由红细胞输注的弱刺激产生的仍然有限。考虑到记忆淋巴细胞具有干细胞特有的功能属性，如稳态自我更新，我们和其他人假设它们重新激活了造血干细胞遗传程序的一部分。为了支持这一观点，我们发表了记忆B细胞、记忆CD8+ T细胞和造血干细胞之间共享的共同转录特征。我们已经证明，相对于寿命较短的细胞，转录因子Pou6f1在记忆B和CD8+ T细胞中选择性上调。Pou6f1是转录因子Pou结构域家族的成员，是Pou5f1（又名Oct4）的一个成员。Oct4是胚胎干细胞自我更新的主要调节因子之一，它建立了一个稳定的、自我增强的遗传回路，指导自我更新基因的主动转录，同时保持分化特异性转录因子处于关闭但稳定的状态。我们相信Pou6f1在记忆T和B细胞中的功能与胚胎干细胞中的Oct4类似。中心假设是Pou6f1指导RBC同种免疫的记忆抗体应答。这一假设导致了一组预测，我们将在一系列遗传和生化实验中进行体内测试，这些实验结合了我们最近用k和HOD RBC同种免疫模型生成的Pou6f1 floxed小鼠。目的1是测试T和B细胞中Pou6f1表达是产生长寿命的、可加强的RBC同种抗体应答所需的预测。目的2是测试的预测，在记忆T和B淋巴细胞中持续的Pou6f1的表达是需要维持回忆反应RBC同种异体免疫，和Pou6f1是需要维持抗原特异性记忆淋巴细胞的应答稳态细胞因子信号。随着时间的推移，我们预计驱动RBC抗体产生的分子电路的鉴定将为进一步的临床开发提供治疗和诊断靶点。

DESCRIPTION (provided by applicant): RBC alloimmunization remains a common clinical problem in transfusion medicine. Alloantibodies are responsible for hemolytic transfusion reactions; leading to substantial morbidity and occasional mortality. For those patients unfortunate enough to make multiple alloantibodies, provision of compatible RBCs can be both time and resource intensive. In some cases, this can result in an inability to locate an otherwise life-saving therapy. Despite their clinical importance, our understanding of how long-lived memory RBC alloantibody responses are generated by the weak stimulus of RBC transfusion remains limited. Given that memory lymphocytes share functional attributes typically reserved for stem cells such as homeostatic self-renewal, we and others have hypothesized that they have reactivated a portion of the hematopoietic stem cell genetic program. In support of this idea, we published a common transcriptional signature shared between memory B cells, memory CD8+ T cells and hematopoietic stem cell. We have gone on to show that the transcription factor Pou6f1 is selectively upregulated in memory B and CD8+ T cells relative to shorter-lived cells. Pou6f1 is a member of the Pou-domain family of transcription factors and is a paralog of Pou5f1 (aka Oct4). Oct4 serves as one of the master regulators of embryonic stem cell self-renewal; establishing a stable, self-reinforcing genetic circuit that directs active transcription of self-renewal genes while maintaining differentiation specific transcription factor in an off, but poised state. We believe Pou6f1 functions in memory T and B cells in a manner similar to Oct4 in embryonic stem cells. The central hypothesis is that Pou6f1 directs memory antibody responses to RBC alloimmunization. This hypothesis leads to a set of predictions that we will test in vivo in a series of genetic and biochemical experiments combining Pou6f1 floxed mice we have recently generated with both the k and HOD RBC alloimmunization models. Aim 1 is to test the prediction that Pou6f1 expression in both T and B cells is required for the generation of long-lived, boostable RBC alloantibody responses. Aim 2 is to test the prediction that continued Pou6f1 expression in memory T and B lymphocytes is required to maintain recall responses to RBC alloimmunization, and that Pou6f1 is required to maintain responsiveness of antigen specific memory lymphocytes to homeostatic cytokine signals. In the fullness of time, we anticipate that identification of the molecular circuitry driving RBC antibody production will provide therapeutic and diagnostic targets for further clinical development.