AGING--ANTIBODY RESPONSE TO BACTERIAL AND VIRAL AGS

衰老——对细菌和病毒 AGS 的抗体反应

基本信息

批准号：
6372074
负责人：
Paolo Casali
金额：
$ 34.79万
依托单位：
WEILL MEDICAL COLL OF CORNELL UNIV
依托单位国家：
美国
项目类别：
财政年份：
1997
资助国家：
美国
起止时间：
1997-08-15 至 2003-07-31
项目状态：
已结题

项目摘要

The overall scope of this proposal is to uncover the mechanisms underlying the generation of antibodies (Abs) to exogenous antigens (Ags) as they change with aging. Aged people display abnormal Ab responses to exogenous Ags, particularly those on bacteria and viruses, including Streptococcus pneumoniae (Pneumococcus) and influenza virus, and they are affected with significant rates of morbidity and mortality following infection with these and other microbial pathogens. Similarly abnormal Ab responses to microbial Ags have been found in aged mice and have been related to alterations of the clonal composition of the B cell repertoire. We hypothesize that in aged humans the-abnormal responses to microbial pathogens are due to the recruitment of clonotypes different from those recruited in young adults in response to the same exogenous Ags, and may reflect alterations of the composition of the steady- state B cell repertoire. We also hypothesize that, in addition to an altered B cell clonotypic recruitment, the mechanisms of somatic B cell diversification, i.e., Ig V(D)J gene hypermutation and selection by Ag, are ineffective, thereby leading to imperfect affinity maturation of Ag-induced Abs in aged subjects. Such ineffective somatic selection mechanisms may reflect a defect inherent to the B cell mutational machinery, perhaps compounded by a defective T cell help, as documented in the elderly, and would result in abnormal responses to T cell-independent as well as T cell-dependent Ags. To test our hypotheses, we propose to vaccinate with Pneumococcus polysaccharide and influenza virus vaccines aged subjects (65 years of age and older) and, for comparison, young adults (20 to 45 years of age), and to: (i) analyze the phenotypic and clonotypic composition of the B cell repertoire as a whole, and those of some of its subsets, as well as the phenotype, the frequency, and the clonotypic assortment of the precursors of cells producing IgM, IgG, and IgA Abs to Pneumococcus and influenza virus Ags; under maximal activating conditions and absence of activating stimuli; (ii) generate monoclonal antibodies (mAbs) to Pneumococcus and to influenza virus Ags, analyze the mAb Ag-binding properties, the primary structure of their VHDJH and VLJL segments, and their status with respect to somatic point-mutations; and, finally, (iii) validate the data provided by the structural and functional analyses of selected B cell clones to Pneumococcus and influenza virus, and extend them to multiple elements of individual clonotypes to measure the extent of intraclonal diversification by Ig gene "repertoire cloning" in combinatorial phage display libraries. The cellular and molecular features of the Ab response to Pneumococcus and influenza virus in aged subjects will be compared not only to those of the corresponding responses in young adults, but also to those of the natural and Ad-induced Ab responses to other microbial Ags in aged subjects, and may, therefore, help design specific means of therapeutic intervention.

该提议的总体范围是揭示机制抗外源抗原的抗体产生（ABS）的基础（AGS）随着衰老的变化。老年人表现出异常的AB 对外源性AG的反应，特别是细菌的AG和病毒，包括肺炎链球菌（肺炎）和流感病毒，它们受到大量率的影响感染这些和其他感染后的发病率和死亡率微生物病原体。同样，对微生物的AB反应异常 AG在老年小鼠中发现了 B细胞库的克隆组成的改变。我们假设在老年人中，对微生物的反应是病原体是由于募集的clonotypes与那些是在年轻人中招募的，以响应同一外源性 AGS，并且可能反映了稳态组成的改变状态B细胞库。我们还假设，除了变化的B细胞clonotypic募集，体细胞的机制 B细胞多样化，即Ig V（d）J基因过度次数和 Ag的选择无效，从而导致不完美老年受试者AG诱导的ABS的亲和力成熟。这样的无效的躯体选择机制可能反映了缺陷 B细胞突变机器固有的，也许是复杂的如老年人所记录的，有缺陷的T细胞帮助导致对T细胞独立和T的异常反应依赖细胞的AG。为了检验我们的假设，我们建议接种疫苗多糖和流感病毒疫苗的肺炎球菌与年龄受试者（65岁及以上），以比较年轻成人（20至45岁），至：（i）分析表型 B整个B细胞库的克隆型组成，以及其中一些子集以及表型，频率和细胞前体的clonotypic分类产生IgM，IgG和IgA ABS至肺炎球菌和流感病毒 AGS；在最大激活条件下，没有激活刺激；（ii）生成对肺炎球菌的单克隆抗体（mAb）以及为流感病毒AGS分析mAb ag结合特性，他们的VHDJH和VLJL段的主要结构及其关于躯体突变的状态；最后，（iii）验证结构和功能提供的数据分析选定的B细胞克隆到肺炎球菌和流感病毒，并将其扩展到个体的多个要素克隆型来衡量通过组合噬菌体显示中的IG基因“曲目克隆” 库。 AB响应的细胞和分子特征在老年受试者中，肺炎球菌和流感病毒将是不仅与年轻的相应响应相比成年人，也适用于自然和广告引起的AB 对老年受试者的其他微生物AG的反应，可能因此，帮助设计特定的治疗干预手段。