AGING--ANTIBODY RESPONSE TO BACTERIAL AND VIRAL AGS

衰老——对细菌和病毒 AGS 的抗体反应

• 批准号: 2748547
• 负责人: Paolo Casali
• 金额: $ 32.33万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-15 至 2002-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2748547
• 关键词: B lymphocyte; Orthomyxoviridae; Streptococcus pneumoniae; age difference; aging; antibody formation; antigen antibody reaction; bacterial antigens; bacterial polysaccharides; bacterial vaccines; cellular immunity; clinical research; enzyme linked immunosorbent assay; human old age (65+); human subject; immunogenetics; immunoglobulin A; immunoglobulin G; immunoglobulin M; influenza vaccines; molecular cloning; nucleic acid sequence; point mutation; polymerase chain reaction; virus antigen; young adult human (21-34)

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.

本提案的总体范围是揭示 作为产生针对外源性抗原的抗体（Ab）的基础 (Ags)随着年龄的增长而变化。老年人显示异常抗体 对外源性抗原的反应，特别是对细菌和 病毒，包括肺炎链球菌（肺炎球菌）和 流感病毒，他们受到影响的显着率 感染这些和其他疾病后的发病率和死亡率 微生物病原体对微生物的类似异常Ab反应 Ags在老年小鼠中被发现， B细胞库克隆组成的改变。我们 假设老年人对微生物的异常反应 病原体是由于招募的克隆型不同， 那些在年轻人中招募的人， 可能是因为他们改变了自己的生活方式， 所述B细胞库。我们还假设，除了 改变的B细胞克隆型募集，体细胞的机制， B细胞多样化，即，IG V（D）J基因超突变和 选择的Ag，是无效的，从而导致不完美的 在老年受试者中Ag诱导的Ab的亲和力成熟。等 无效的体细胞选择机制可能反映了 固有的B细胞突变机制，也许加剧了 一个有缺陷的T细胞帮助，如老年人的记录， 导致对T细胞非依赖性以及T 细胞依赖性抗原为了验证我们的假设，我们建议接种疫苗 肺炎球菌多糖和流感病毒疫苗老化 受试者（65岁及以上）和年轻受试者 成年人（20至45岁），并：（i）分析表型 和作为整体的B细胞库的克隆型组成，和 它的一些子集，以及表型， 频率和细胞前体的克隆型分类 产生肺炎球菌和流感病毒的IgM、IgG和伊加抗体 在最大活化条件和无活化条件下 刺激物;（ii）产生抗肺炎球菌单克隆抗体（mAb 和流感病毒Ag，分析mAb Ag结合特性， 它们的VHDJH和VLJL片段的一级结构，以及它们的 关于体细胞点突变的状态;以及，最后，（iii） 验证结构和功能提供的数据 选择的B细胞克隆对肺炎球菌和流感的分析 病毒，并将其扩展到个体的多个元素 克隆型，以测量克隆内多样化的程度， 组合噬菌体展示技术中的IG基因“库克隆” 图书馆.抗体应答的细胞和分子特征 肺炎球菌和流感病毒在老年受试者将 不仅与年轻人的相应反应相比， 成年人，而且还对那些自然和广告诱导的抗体 老年受试者对其他微生物抗原的反应，可能， 因此，帮助设计具体的治疗干预手段。