Pathological B Cells: Novel Strategies to Prevent and Treat Chronic GVHD

摘要 在这次更新中，我们继续努力开发使异基因造血干细胞 移植(HCT)对患者的毒性较小。我们的主要目标是制定针对慢性移植物的策略。 对抗宿主病(CGVHD)相关免疫病理而不阻断关键的免疫治疗作用 Hct的。B细胞在cGVHD中的病理生物学作用已得到证实，但区别于疾病中介的B细胞 子集仍然难以捉摸。仅针对变异的B细胞很重要，因为我们已经发现全球 利妥昔单抗去除外周B细胞使所谓的免疫稳态改变和cGVHD永久化 在无法恢复综合B细胞室的患者中。在上一个资助期，我们澄清了 病理性B细胞激活因子和NOTCH2如何促进异常B细胞受体 红细胞压积后发出信号。根据已知的B细胞成熟过程中的BCR信号事件，我们假设 抗原高反应性和依赖SYK的B细胞可以在不影响免疫稳态的情况下被消除。在……里面 临床前研究和临床试验表明，bcr-近端蛋白SYK的抑制作用被消除 异常激活B细胞，恢复B细胞稳态。我们也开始剖析小说 支持BCR高反应性的机制。已公布的证据和我们额外的初步数据， 包括单细胞RNA-Seq数据集，为这一建议形成了坚实的科学基础，并提供了我们目前的 B细胞的异常激活和效应功能通路可以有效地 目标是cGVHD。在目前的提案中，我们解决了关于人类B细胞的知识中的主要空白 导致慢性移植物抗宿主病B细胞耐受性持续丧失的程序设计。我们的实验方法 需要在我们的体外B细胞检测系统中对cGVHD患者样本进行研究，并在小鼠身上进行平行实验 以B细胞条件性和可诱导性基因敲除小鼠为供体验证分子机制。具体来说，我们 将描绘促进病理性B细胞的分子通路，并确定不同的疾病中介 CGVHD B细胞的功能。我们将追求三个具体目标：1)BCR后SYK蛋白的持久性 参与，2)II期临床cGVHD患者阻断SYK和恢复体液免疫的能力 试验3)抗体和炎性细胞因子产生的分子基础。我们将定义目标 我们将展示的B细胞亚群中的信号通路在cGVHD中具有病理性B效应细胞功能。我们的 该提案依赖于团队科学概念，并由杜克临床试验的合作研究人员实现 团队(Horwitz博士和Rizzieri博士)和杜克癌症研究所统计组(Li博士和Owzar博士)。我们的团队 仍然站在阐明人类B细胞信号异常和测试小分子的努力的前沿 慢性移植物抗宿主病患者的抑制剂。

ABSTRACT In this renewal, we continue efforts to develop agents that will make allogeneic hematopoietic stem cell transplantation (HCT) less toxic for patients. Our major objective is to develop strategies that target chronic graft versus host disease (cGVHD)-related immune pathology without blocking the critical immunotherapeutic effects of HCT. B cells have a substantiated pathobiological role in cGVHD, but distinguishing disease-mediating B cells subsets remains elusive. Targeting only aberrant B cells is important because we have found that global abrogation of peripheral B cells with rituximab perpetuates so-called altered immune homeostasis and cGVHD in patients unable to recover a comprehensive B-cell compartment. In the previous funding period, we elucidated how pathological B Cell Activating Factor (BAFF) and NOTCH2 promote aberrant B Cell Receptor (BCR)- signaling after HCT. Based on known BCR signaling events during B cell maturation, we hypothesized that antigen-hyperresponsive and SYK-reliant B cells can be eliminated without affecting immune homeostasis. In preclinical studies and in the clinical trial, we showed that inhibition of the BCR-proximal protein, SYK, eliminated aberrantly activated B cells and afforded recovery of B-cell homeostasis. We have also begun to dissect novel mechanisms underpinning BCR hyper-responsiveness. Published evidence and our additional preliminary data, including a single cell RNA-Seq dataset, form the solid scientific basis for this proposal and afford our current overarching hypothesis that aberrant activation and effector function pathways in B cells can be effectively targeted in cGVHD. In the current proposal, we address major gaps in our knowledge regarding human B-cell programming that confer a propensity for ongoing loss of B cell tolerance in cGVHD. Our experimental approach entails study of cGVHD patient samples in our ex vivo B-cell assay system and parallel experiments in mice using B-cell conditional and inducible knockout mice as donors to verify molecular mechanisms. Specifically, we will delineate molecular pathways that promote pathological B cells and determine the distinct disease-mediating functions of cGVHD B cells. We will pursue three specific aims: 1) persistence of SYK protein after BCR engagement, 2) the ability to block SYK and restore humoral immunity in cGVHD patients in a Phase II clinical trial 3) molecular underpinnings of antibody and inflammatory cytokine production. We will define targetable signaling pathways in B cell subsets that we will show have pathological B-effector cell functions in cGVHD. Our proposal relies on a team science concept and is made possible by co-investigators on the Duke clinical trial team (Drs. Horwitz and Rizzieri) and Duke Cancer Institute statistical group (Drs. Li and Owzar). Our group remains at the forefront of efforts elucidating aberrant human B-cell signaling and testing small molecule inhibitors in chronic GVHD patients.