Molecular mechanisms for TNF-mediated inhibition of B lymphocyte function

描述（由申请人提供）：衰老与个体产生保护性免疫反应的能力下降有关。了解与年龄相关的免疫功能损伤的分子机制将有助于预防传染病和提高老年人的生物生活质量。衰老的特征是血浆中促炎细胞因子（如tnf - α）水平升高，这些细胞因子可能具有有害影响，因为它们与老年人几种致残疾病的发病机制有关。我们假设老年人的这种促炎状态，称为炎症，损害了个体产生保护性抗体和对疫苗接种作出反应的能力。具体来说，我们的初步数据表明，老年典型的炎症反应增加也是由B淋巴细胞引起的，这对B淋巴细胞的功能产生了负面影响，包括免疫球蛋白（Ig）的类开关重组（CSR）能力，这对外源抗原特异性抗体的最佳效应功能至关重要。在这个R21应用中，我们将描述导致老年人B细胞反应减少的新分子机制，这在未来应该能够用作改善老年人B细胞反应的新靶点。我们将评估从老年人体内分离的B细胞是否比从年轻人体内分离的B细胞产生更多的tnf - α，确定哪种B细胞亚群产生tnf - α，以及与已知的其他细胞类型相比，这种细胞因子的主要来源是多少。具体的问题是，来自老年人的B细胞在Ig类转换中的内在缺陷是否由于B细胞产生tnf - α的初始能力。这也将与这些受试者体内抗流感疫苗反应相关。我们将通过预先培养含有tnf - α的B细胞来描述tnf - α损害B细胞进行CSR能力的机制，并评估是否可以通过在培养的B细胞中添加抗tnf - α抗体来“拯救”体外Ig类开关。结果测量将是我们之前发现的分子生物标志物，用于预测最佳B淋巴细胞反应。本R21应用程序中提出的实验提供了一种创新的方法来表征老年人减少B细胞反应的进一步机制。这些研究应立即对有效疫苗的关键开发产生影响，以保护老年人免受老年典型疾病的侵害。

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.