Molecular mechanisms for TNF-mediated inhibition of B lymphocyte function

描述(由申请人提供)：衰老与个体建立保护性免疫反应的能力下降有关。了解老年性免疫功能受损的分子机制将有助于预防传染病，提高老年人的生物生活质量。衰老的特征是血浆促炎细胞因子水平升高，如肿瘤坏死因子-α，这些细胞因子可能会产生有害的影响，因为它们与老年人几种致残性疾病的发病机制有关。我们假设，老年人这种被称为炎症的促炎状态，会削弱个体产生保护性抗体和对疫苗接种做出反应的能力。具体地说，我们的初步数据表明，老年人典型的炎症反应增加也是由B淋巴细胞贡献的，这对它们的功能产生了负面影响，包括经历免疫球蛋白(Ig)的类切换重组(CSR)的能力，这对外源抗原特异性抗体的最佳效应功能至关重要。在R21的应用中，我们将描述导致老年人B细胞反应降低的新的分子机制，这些机制在未来应该能够被用作改善B细胞反应的新靶点。我们将评估从老年个体体外分离的B细胞是否比年轻个体分离的B细胞产生更多的肿瘤坏死因子-α，确定哪个B细胞亚群产生肿瘤坏死因子-α，以及与其他已知的细胞类型相比产生这种细胞因子的数量。具体的问题是，Ig类转换中老年个体的B细胞的固有缺陷是否源于B细胞最初产生肿瘤坏死因子-α的能力。这也将与这些受试者体内的抗流感疫苗反应相关。我们将通过预先将B细胞培养与肿瘤坏死因子-α共同孵育来研究肿瘤坏死因子-α损害B细胞经历CSR的能力的机制，并评估是否可以在培养的B细胞中加入抗肿瘤坏死因子-α抗体来“挽救”体外Ig类转换。结果指标将是我们以前发现的预测最佳B淋巴细胞反应的分子生物标记物。在R21申请中提出的实验提供了一种创新的方法来表征进一步降低老年人B细胞反应的机制。这些研究应该会对有效疫苗的关键开发产生直接影响，以保护老年人免受典型的老年疾病的影响。

DESCRIPTION (provided by applicant): Aging is associated with a decline in the ability of the individual to mount protective immune responses. Understanding the molecular mechanisms of the age-related impairment in immune functions will help to prevent infectious diseases and improve the biological quality of life in the elderly. Aging is characterized by increased plasma levels of pro-inflammatory cytokines such as TNF-alpha, and these can have deleterious effects as they are implicated in the pathogenesis of several disabling diseases of the elderly. We hypothesize that this pro-inflammatory status of the elderly, called inflammaging, impairs the capacity of the individual to make protective antibodies and to respond to vaccination. Specifically, our preliminary data indicate that the increased inflammatory response typical of old age is also contributed by B lymphocytes and this negatively impacts their function , including the ability to undergo class switch recombination (CSR) of immunoglobulin (Ig), critical for optimal effector function of antibodies specific for exogenous antigens. In this R21 application we will characterize novel molecular mechanisms leading to reduced B cell responses in the elderly which in the future should be able to be used as new targets for their improvement. We will evaluate whether B cells ex vivo isolated from elderly individuals make more TNF-alpha than those from younger ones, determine which B cell subset makes TNF-alpha, and how much compared to other cell types known to be primary sources of this cytokine. Particular questions addressed are whether the intrinsic defect of B cells from elderly individuals in Ig class switch is due to the initial ability of the B cell to make TNF-alpha. This will also be correlated with the in vivo anti-influenza vaccine response in these subjects. We will characterize the mechanisms by which TNF-alpha impairs the ability of B cells to undergo CSR by pre-incubating B cell cultures with TNF-alpha and evaluate if the in vitro Ig class switch can be "rescued" with an anti-TNF-alpha antibody added to cultured B cells. Outcome measures will be molecular biomarkers we have previously discovered to predict optimal B lymphocyte responses. The experiments proposed in this R21 application offer an innovative approach to characterize further mechanisms which decrease B cell responses in elderly individuals. These studies should have immediate impact on crucial development of effective vaccines to protect elderly individuals from diseases typical of old age.