Transitional B cell selection during peripheral B lymphopenia and reconstitution

外周 B 淋巴细胞减少和重建期间的过渡 B 细胞选择

基本信息

批准号：
7250657
负责人：
Michael Paul Cancro
金额：
$ 39.34万
依托单位：
UNIVERSITY OF PENNSYLVANIA
依托单位国家：
美国
项目类别：
财政年份：
2007
资助国家：
美国
起止时间：
2007-04-01 至 2012-03-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): BLyS plays a critical role in integrating B cell homeostasis with specificity-based tolerance mechanisms. This is evidenced by the effects of manipulating BLyS or its receptors, as well as the links between the BLyS/BLyS receptor family and humoral autoimmunity. Recent data and our preliminary results show that the proportion of newly formed B cells surviving transitional selection can be varied based on homeostatic demands. Thus, the stringency of negative selection is relaxed when the demand for newly formed lymphocytes is high, allowing autoreactive clonotypes to mature and enter the follicular and marginal zone pools. These observations suggest that upon cessation of treatments that ablate peripheral pools, altered homeostatic demands will compromise the normal balance of selection and homeostasis. Accordingly, we hypothesize that during lymphoid reconstitution following curtailed marrow output or peripheral B lymphopenia, selective thresholds will be relaxed. We further hypothesize that this will be governed by available BLyS and BLyS receptor levels, and that the emergence of autoreactive specificities can thus be modulated by controlling available BLyS. The studies herein will address these ideas. In aim 1, we will determine how transitional B cell throughput is influenced by reduced marrow output and peripheral B lymphopenia. These experiments will employ BrdU labeling coupled with lymphoid autoreconstitution, drug-induced peripheral B lymphopenia, and mixed marrow chimera studies to determine the throughput and fate of cells under these conditions. In aim 2 we will determine whether the stringency of transitional repertoire selection is relaxed during peripheral lymphopenia or reduced BM output. We will assess selection stringency by monitoring changes in repertoire composition, diversity and specificity across transitional and mature subsets. In addition, we will directly test whether autoreactive specificities normally eliminated at the transitional checkpoint are afforded entry to mature compartments. These experiments will use flow cytometry, limiting dilution and single cell specificity analyses in normal and transgenic mice. In aim 3, we will establish whether normal selection can be restored by adjusting BLyS levels or responsiveness during replenishment of peripheral pools. We will assess whether reduced available BLyS levels will restore normal selective stringency by in vivo treatment with soluble TACI Ig or neutralizing anti-BLyS antibody in normal and autoimmune models.

描述（由申请人提供）：BLyS 在将 B 细胞稳态与基于特异性的耐受机制整合方面发挥着关键作用。操纵 BLyS 或其受体的作用以及 BLyS/BLyS 受体家族与体液自身免疫之间的联系证明了这一点。最近的数据和我们的初步结果表明，新形成的 B 细胞在过渡选择中幸存的比例可以根据稳态需求而变化。因此，当对新形成的淋巴细胞的需求较高时，阴性选择的严格性就会放松，从而允许自身反应性克隆型成熟并进入滤泡和边缘区池。这些观察结果表明，在停止消除外周池的治疗后，体内平衡需求的改变将损害选择和体内平衡的正常平衡。因此，我们假设在骨髓输出减少或外周 B 淋巴细胞减少后的淋巴重建过程中，选择性阈值将会放宽。我们进一步假设这将由可用的 BLyS 和 BLyS 受体水平控制，并且因此可以通过控制可用的 BLyS 来调节自身反应特异性的出现。本文的研究将解决这些想法。在目标 1 中，我们将确定骨髓输出减少和外周 B 淋巴细胞减少如何影响移行 B 细胞吞吐量。这些实验将采用 BrdU 标记结合淋巴自动重建、药物诱导的外周 B 淋巴细胞减少和混合骨髓嵌合体研究来确定这些条件下细胞的吞吐量和命运。在目标 2 中，我们将确定在外周淋巴细胞减少或 BM 输出减少期间过渡库选择的严格性是否放松。我们将通过监测过渡和成熟子集的库组成、多样性和特异性的变化来评估选择的严格性。此外，我们将直接测试通常在过渡检查点消除的自身反应特异性是否能够进入成熟的区室。这些实验将在正常和转基因小鼠中使用流式细胞术、有限稀释和单细胞特异性分析。在目标 3 中，我们将确定是否可以通过调整 BLyS 水平或补充外周池期间的反应性来恢复正常选择。我们将评估在正常和自身免疫模型中用可溶性 TACI Ig 或中和抗 BLyS 抗体进行体内治疗，降低的可用 BLyS 水平是否会恢复正常的选择性严格性。