Selection of the B cell repertoire in senescence

衰老过程中 B 细胞库的选择

• 批准号: 7110159
• 负责人: RICHARD L RILEY
• 金额: $ 29.59万
• 依托单位: UNIVERSITY OF MIAMI SCHOOL OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-30 至 2009-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7110159
• 关键词: B cell receptor; B lymphocyte; animal old age; antibody specificity; antigen presentation; cell age; cell differentiation; cell senescence; enzyme linked immunosorbent assay; flow cytometry; immune response; immunoglobulin genes; interleukin 7; laboratory mouse; lymphopoiesis; polymerase chain reaction; terminal nick end labeling

B lymphopoiesis is severely compromised in murine senescence. The defect in B lymphopoiesis in senescence predominantly "maps" to the pro-B to pre-B cell transition, a stage critically dependent upon signaling via the pre-B cell receptor (ix/_.5/VpreB; preBCR) and the growth cytokine IL-7. We propose that in senescence the development ofpre-B cells is subject to increasingly stringent negative selection. This results primarily from decline in expression of the preBCR, poor responses to IL-7, and increased susceptibility to apoptosis. Rather than random loss of pre-B cells in old age, we propose contraction of the pre-B cell pool in a clone-specific manner. Preferentially selected would be those few pre-B ceils which maintain the capacity to undergo preBCR/IL-7 mediated growth and survival. This results in a "reshaping" of the pre-B and immature B cell specificity repertoires in senescence. To address this hypothesis, we propose 3 Specific Aims. Specific Aim 1 asks "Is the loss of pre-B cells in old age random or clone-specific?". In this Specific Aim, Vh family use, CDR3 diversity, capacity to express functional preBCRs, and the role of the microenvironment in altering B lineage development and "read-out" of the antibody repertoire will be addressed. Specific Aim 2 asks "Does 'repertoire reshaping' at the pre-B stage affect the read-out of the B cell repertoire in old age?". Here, Vh use and CDR3 diversity will be assessed in immature B cells from aged mice and compared with that of pre-B cells. Furthermore, the antibody specificity of immature B cells in aged mice will be assessed and the fate of these immature B cells in the periphery will be determined. Specific Aim 3 asks "Does apoptotic stress result in changes in the pre-B and immature B cell repertoires in senescence?". Sensitivity to apoptosis and the expression of apoptotic/survival molecules in aged B cells will be determined. The effects of the environment on apoptotic susceptibility among aged B lineage cells will be assessed. Finally, the role of apoptosis in modulating the pre-B/immature B cell repertoires in senescence will be tested. These studies will advance understanding of the immune defects which accompany old age and their cellular and molecular mechanisms.

B淋巴细胞在鼠衰老中严重损害。衰老中B淋巴细胞的缺陷主要是“地图”到Pro-B细胞转变，这是通过PRE-B细胞受体（IX/_。5/_。5/vpreb; prebCR）和生长细胞因子IL-7的信号转化的阶段。我们建议，在衰老中，PRE-B细胞的发展受到越来越严格的负面选择。这主要是由于PEBCR表达下降，对IL-7的反应不良以及对凋亡的敏感性增加。我们没有以克隆特异性的方式提出pre-b细胞池的收缩，而不是在老年内随机丢失。优先选择的是维持容量的少数几个前天花板 要经历Prebcr/IL-7介导的生长和生存。这导致衰老中的前B和未成熟B细胞特异性库的“重塑”。为了解决这一假设，我们提出了3个具体目标。特定的目标1问：“在老年时期或特异性克隆特异性的老年pre-b细胞的损失？”。在这个具体目标中，将解决VH家族使用，CDR3多样性，表达功能性PEBCR的能力以及微环境在改变B谱系发展中的作用，并解决抗体库的“读出”。特定的目标2问：“'曲目在B阶段是否重塑”会影响老年B细胞曲目的读数吗？”。在这里，将在老年小鼠的未成熟B细胞中评估VH的使用和CDR3多样性，并将其与前B细胞的多样性进行比较。此外，将评估年龄小鼠中未成熟B细胞的抗体特异性，并将确定这些未成熟的B细胞的命运。 特定的目标3询问“凋亡应力是否会导致衰老中的前B和未成熟B细胞库的变化？”。将确定对凋亡的敏感性和老年B细胞中凋亡/存活分子的表达。将评估环境对老化B谱系细胞凋亡易感性的影响。最后，将测试细胞凋亡在调节衰老中的B/未成熟B细胞库中的作用。这些研究将提高人们对伴随老年及其细胞和分子机制的免疫缺陷的了解。