Human Transitional B Cells: Homeostasis, Function, and Impact of BCDT

项目总结(见说明)： B细胞在系统性红斑狼疮(SLE)和类风湿关节炎(RA)的发病机制中起重要作用。一个 项目I的主要焦点是确定移行B细胞的骨髓发育线索和外周周转 以及在系统自身免疫中可能受到干扰的细胞因子环境是如何调节这一过程的。这是假设的 自身免疫性疾病与B细胞发育过程中过渡性B细胞平衡失调有关 随着从骨髓(BM)中涌出的移行B细胞数量的变化，内微环境 调节这一过程的信号(干扰素、肿瘤坏死因子)，以及进入成熟室的信号阈值 (Baff)。另一方面，我们发现SLE患者具有明显的循环过渡性扩张 B细胞去除治疗(BCDT)后的细胞进入长期临床缓解，而SLE和RA患者 记忆重建越快，疾病复发的时间越早。这项建议的重点是及早了解 系统性红斑狼疮和类风湿关节炎患者BCDT后B细胞稳态及调节B细胞重建的因素 具体目标将定义：1.自身免疫中人类过渡性B细胞的动态平衡紊乱 BCDT后不同B细胞亚群重建平衡的调节因素； 过渡性B细胞和调节性T细胞的相互调节以及这种调节在自身免疫性疾病和 在BCDT之后。具体地说，我们将使用B细胞耗尽作为工具来定义人类B细胞发育的动力学 多参数流式细胞术。过渡性B细胞的寿命和周转率将通过重水进行评估 标记，复制历史，细胞周期，以及生存和选择的描绘。细胞因子环境对新生血管生成的影响 将检查骨髓B细胞的造血功能。本项目将探索BCDT的结果反映 保护性(调节性、抗炎性)和效应性(原板层)B细胞之间的平衡及其 相应的细胞因子。过渡性B细胞功能的描绘包括抗炎的产生 IL-10和TGFb等细胞因子与调节性T细胞(Treg)发育的支持。我们将定义人类是否 B细胞亚群不同地支持Treg扩展或不同地易受Treg抑制，如果此函数 自身免疫设置的变化，以及BCDT如何改变这些异常。关于动态平衡的阐明 人类过渡性B细胞的调控将代表着人类B细胞生物学的重大进展。这项研究建议 也将帮助我们理解自身免疫性疾病中B细胞发育是如何失调的，以及耗竭是如何导致的 病情改善，在某些情况下，可长期缓解疾病。

PROJECT SUMMARY (See instructions): B cells play a critical role in the pathogenesis of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). A major focus of Project I is to define the bone marrow developmental cues and peripheral turnover of transitional B cells and how cytokine milieu, which may be perturbed in systemic autoimmunity, regulates this process. It is hypothesized that autoimmune disease is as.sociated with dysregulation of transitional B cell homeostasis during B cell development with alterations in the numbers of transitional B cells emerging from the bone marrow (BM), the inicroenvironmenlal signals that modulate this process (IFN, TNF), and the signaling threshold for progression to the mature compartinent (BAFF). On the other hand, we have found that SLE patients with a prominent expansion of circulating transitional cells after B cell depletion therapy (BCDT) enter long-term clinical remission, whereas both SLE and RA patients with more rapid memory reconstitution experience earlier relapse of disease. The focus of this proposal is to understand early B cell homeostasis and the factors that regulate B cell reconstitution after BCDT in SLE and RA through the following specific aims which will define: 1. the perturbations in homeostasis of human transitional B cells in autoimmune di.sease; 2. the factors which regulate the balance of reconstitution of distinct B cell subsets after BCDT; and 3. the reciprocal regulation of transitional B cells and regulatory T cells and how this is altered in autoimmune disease and after BCDT. Specifically, we will define the dynamics of B cell development in humans using B cell depletion as a tool and multi-parameter flow cytometry. The lifespan and turnover of transitional B cells will be assessed by heavy water labeling, replication history, cell cycle, and delineation of survival and .selection. The effects of cytokine milieu on new BM B cell lyinphopoeisis will be examined. This project will explore the hypothesis that the outcome of BCDT rellects the balance between protective (regulatory, anti-inflammatory) and effector (prointlammatoiy) B cells and their corresponding cytokines. Transitional B cell functions to delineate include the production of anti-intlammatory cytokines such as IL-10 and TGFB and support of regulatory T cell (Treg) development. We will define whether human B cell subsets differentially support Treg expansion or are differentially susceptible to Treg suppression, if this function changes in autoimmune settings, and how these abnormalities are modified by BCDT. Elucidation of the homeostatic regulation of human transitional B cells will represent a major advance in human B cell biology. The research proposed will also help us understand how B cell development is dysregulated in autoimmune disease and how depletion induces improvement and, in some cases, long-lasting disea.se remission.