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

描述(由申请人提供)：衰老会导致个体建立保护性免疫反应的能力下降。衰老的免疫系统还会增加炎症，从而对心脏和神经系统等其他重要系统产生负面影响。老年人的免疫系统不仅影响个人的生活质量，而且还影响抵御传染病和癌症的能力。我们已经证明，衰老与B细胞的自主缺陷有关，B细胞对最佳健康非常重要，因为它们产生对疫苗和传染病以及其他功能反应所需的抗体。这些缺陷/生物标志物包括：免疫球蛋白(Ig)类开关重组(CSR)、激活诱导型胞苷脱氨酶(AID)和转录因子E47。援助对于CSR是必要的，这是产生保护性抗体的过程，也是B细胞功能的一个很好的衡量标准。我们推测，老年人B细胞功能受损的一个机制是，与年轻成人未受刺激的人B细胞相比，老年人的microRNA(MiR)-155、miR-16和其他miR显著增加，使其对进一步的刺激“难以”，这是由于B细胞刺激后诱导的AID水平较低。该方案的目的是鉴定老年人未受刺激的B细胞中上调的miRs，描述其上调的分子途径及其作用机制，并通过设计针对这些miRs的寡核苷酸来开始纠正这些缺陷。我们建议对B细胞亚群进行分类，进行miR微阵列，并将最多增加的miR水平与AID相关联。在第二个目标中，我们将确定老年B细胞中特定MIR增加的分子机制以及特定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在B细胞培养中添加阻断特定miR功能(抗配子)的寡核苷酸来“拯救”较低的体外CSR。这项拨款中提出的实验为进一步表征降低老年人B细胞反应的机制提供了一种创新的方法。这些研究应有助于制定有效的治疗战略，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.