Micro-RNAs: a new mechanism negatively regulating B cell responses in the elderly

描述（由申请人提供）：衰老导致个体产生保护性免疫应答的能力下降。老化的免疫系统也会对其他重要系统产生负面影响，如心脏和神经系统，导致炎症增加。老化的免疫系统不仅影响个体的生活质量，还影响保护免受传染性病原体和癌症的能力。我们已经证明，衰老与B细胞的自主缺陷有关，B细胞对最佳健康很重要，因为它们产生对疫苗和传染病的反应以及其他功能所必需的抗体。这些缺陷/生物标志物包括：免疫球蛋白（IG）类别转换重组（CSR）、激活诱导的胞苷脱氨酶（AID）和转录因子E47。AID是CSR（产生保护性抗体的过程）所必需的，也是衡量B细胞功能的一个很好的指标。我们假设B细胞功能的老年损伤的机制（对此我们有初步数据）是，与年轻成人未刺激的人B细胞相比，老年人中的microRNA（miR）-155、miR-16和其他miR显著更高，使得它们对进一步刺激“难治”，结果是B细胞刺激后诱导的AID水平更低。本提案的目的是鉴定来自老年个体的未刺激B细胞中上调的miR，表征其上调的分子途径以及其作用机制，并开始通过设计靶向这些miR的寡核苷酸来校正这些缺陷。我们建议对B细胞的亚群进行分类，进行miR微阵列，并将增加最多的miR的水平与AID相关联。在第二个目标中，我们将鉴定老年B细胞中特定miR增加以及特定miR下调AID的分子机制。在第三个目标中，我们将评估是否可以通过向B细胞培养物中添加阻断特定miR功能的寡核苷酸（miR）来“拯救”较低的体外CSR。这项研究提供了一种创新的方法来进一步表征老年人B细胞反应减少的机制。这些研究应有助于制定有效的治疗策略，以保护老年人免受老年典型疾病的影响。

DESCRIPTION (provided by applicant): Aging generates a decline in the ability of the individual to mount protective immune responses. The aged immune system also negatively impacts other important systems, such as the cardiac and nervous systems, by contributing to increased inflammation. The aged immune system not only impacts the quality of life of the individual but also the ability to be protected from infectious agents and cancers. We have shown that aging is associated with autonomous defects in B cells which are important for optimal health because they produce antibodies necessary for responses to vaccines and infectious diseases as well as other functions. These defects/biomarkers include: immunoglobulin (Ig) class switch recombination (CSR), activation-induced cytidine deaminase (AID) and the transcription factor E47. AID is necessary for CSR, the process that generates protective antibodies, and is a good measure of B cell function. We hypothesize that a mechanism for the aged impairment in B cell function, for which we have preliminary data, is that microRNA (miR)-155, miR-16 and other miRs are significantly higher in aged as compared with young adult unstimulated human B cells, making them "refractory" to further stimulation with the result of lower levels of AID induced after B cell stimulation. The objectives of this proposal are to identify miRs up-regulated in unstimulated B cells from elderly individuals, characterize the molecular pathways for their up-regulation as well as their mechanism of action, and begin to correct these defects by designing oligonucleotides which target these miRs. We propose to sort subsets of B cells, perform a miR microarray and correlate levels of the most increased miRs with AID. In the second aim we will identify molecular mechanisms for increases of particular miRs in aged B cells as well as for particular miRs down-regulating AID. In the third aim we will evaluate if lower in vitro CSR can be "rescued" by adding oligonucleotides blocking particular miR function (antagomirs) to B cell cultures. The experiments proposed in this grant offer an innovative approach to further characterize mechanisms which decrease B cell responses in elderly individuals. These studies should contribute to development of effective therapeutic strategies to protect elderly individuals from diseases typical of old age.