HORMONAL RESTORATION OF A FUNCTIONAL THYMUS DURING AGING

描述：（改编自申请人的摘要）：来自老年人的巨噬细胞 大鼠不能对经典的T细胞衍生的细胞因子作出反应， 干扰素-γ（IFN-γ），在体外，如通过它们未能 分泌超氧阴离子和肿瘤坏死因子-α（TNF-α）。 更 重要是，分泌生长激素的同基因垂体移植物可以 逆转老年大鼠巨噬细胞的这些缺陷反应， IFN-γ。 由于生长激素的合成，以及其 促生长肽，胰岛素样生长因子-I（IGF-I），下降 在老年动物和人类中，这些新的结果表明， 来自神经内分泌系统的经典垂体激素发挥作用， 在老年受试者的异常免疫应答中起重要作用。 年轻 在动物中，生长激素最近被发现可以增加许多 免疫反应，包括巨噬细胞和中性粒细胞活化。 不幸的是，对老年人巨噬细胞活化的详细分析 未对受试者进行调查。 凯利博士和他的同事现在提议 系统评价吞噬细胞的活化， 重组IFN-γ在老年大鼠和人类中的作用， 生长激素和IGF-I在这个过程中。 的能力 重组IFN-γ、生长激素和IGF-I以激活巨噬细胞， 通过超氧阴离子的分泌在体外评估老年大鼠， 肿瘤坏死因子-α，克隆T淋巴细胞的抗原呈递， MHC的II类基因、IL-1和IL-6的合成以及细菌和 肿瘤杀伤 类似的研究将通过注射 重组生长激素在老年大鼠体内的应用 这些发现将被扩展 通过确定这些多形核细胞是否 受试者可以像来自年轻供体的受试者一样被IFN-γ引发， 生长激素或IGF-I产生超氧阴离子并杀死细菌， 肿瘤细胞 为了研究生长的细胞机制， 激素和IGF-I能够引发吞噬细胞， 生长激素的基因工程变体将用于阐明 该结构域对于结合其在人类上的受体至关重要， 中性粒细胞，以及这种受体的表达是否在老年人中下降， 科目 生长激素和IGF-I逆转 老年大鼠巨噬细胞的缺陷反应， 将测定巨噬细胞上IFN-γ受体的浓度。 溶液 杂交核糖核酸酶保护和核运行分析将被 用于了解IFN-γ引发的TNF-α减少是否 老年大鼠的巨噬细胞与 这个基因的转录。 类似的实验将在 细胞色素B 558的重链和II类MHC的A α链 分子。 最后，研究人员将使用反向聚合酶链 确定激活的巨噬细胞是否真的合成IGF-I的技术 以及巨噬细胞源性IGF-I的表达是否在衰老过程中下降。 这些 实验将是第一个研究重组体 垂体激素和IFN-γ对老年人吞噬细胞活化作用 动物，从而提供重要的，关于功能的新信息 衰老过程中巨噬细胞和中性粒细胞的活动。

DESCRIPTION: (Adapted from applicant's abstract): Macrophages from aged rats are unable to respond to the classic T cell-derived cytokine, interferon-gamma (IFN-gamma), in vitro, as assessed by their failure to secrete superoxide anion and tumor necrosis factor-alpha (TNF-alpha). More importantly, syngeneic pituitary grafts, which secrete growth hormone, can reverse these defective responses of macrophages from aged rats to IFN-gamma. Since the synthesis of growth hormone, as well as its growth-promoting peptide, insulin-like growth factor-I (IGF-I), decline dramatically in aged animals and humans, these new results suggest that classical pituitary hormones from the neuroendocrine system play an important role in the aberrant immune responses of aged subjects. In young animals, growth hormone has recently been discovered to augment a number of immune responses, including macrophage and neutrophil activation. Unfortunately, a detailed analysis of macrophage activation in aged subjects has not been investigated. Dr. Kelley and coworkers now propose to systematically evaluate the activation of phagocytic cells by recombinant IFN-gamma in both aged rats and humans and to explore the role of both growth hormone and IGF-I in this process. The ability of recombinant IFN-gamma, growth hormone and IGF-I to activate macrophages of aged rats will be assessed in vitro by secretion of superoxide anion, TNF-alpha, antigen presentation to cloned T lymphocytes, expression of class II genes of the MHC, synthesis of IL-1 and IL-6 and bacterial and tumor killing. Similar studies will then be conducted by injecting recombinant growth hormone into aged rats. These findings will be extended to aged humans by determining whether polymorphonuclear cells from these subjects can be primed as well as those from young donors by IFN-gamma, growth hormone or IGF-I to produce superoxide anion and kill bacteria and tumor cells. To investigate the cellular mechanisms by which growth hormone and IGF-I are able to prime phagocytic cells, genetically-engineered variants of growth hormone will be used to elucidate the domain that is critical for binding to its receptor on human neutrophils, and whether expression of this receptor declines in aged subjects. The possibility that growth hormone and IGF-I act to reverse defective responses of macrophages from aged rats by increasing the number of IFN-gamma receptors on macrophages will be determined. Solution hybridization ribonuclease protection and nuclear run-on assays will be used to learn whether the reduction in TNF-alpha by IFN-gamma primed macrophages from aged rats is associated with a reduction in rate of transcription of this gene. Similar experiments will be conducted for the heavy chain of cytochrome b 558 and the Aalpha chain of class II MHC molecules. Finally, the investigators will use reverse polymerase chain technology to determine if activated macrophages actually synthesize IGF-I and if expression of macrophage-derived IGF-I declines during aging. These experiments will be the first to investigate the role of both a recombinant pituitary hormone and IFN-gamma on activation of phagocytic cells from aged animals, and thereby provide important, new information about functional activities of macrophages and neutrophils during aging.