EVOLUTION OF IMMUNE RECOGNITION AND EVASION

免疫识别和逃避的进化

基本信息

批准号：
2518794
负责人：
AUSTIN L. HUGHES
金额：
$ 6.84万
依托单位：
PENNSYLVANIA STATE UNIVERSITY, THE
依托单位国家：
美国
项目类别：
财政年份：
1993
资助国家：
美国
起止时间：
1993-09-30 至 1998-08-31
项目状态：
已结题

项目摘要

The vertebrate immune system includes numerous interacting proteins involved in the recognition and elimination of parasitic organisms. The general goal of this research is to understand the evolution of key molecular components of this system, particularly the molecules encoded by the major histocompatibility complex (MHC), and to understand how immunogenic proteins of parasitic organisms have evolved under natural selection exerted by the host's immune system. The MHC is a multi-gene gamily encoding cell-surface glycoproteins which play an important role in the immune system, binding foreign peptides and presenting them to T cells, thereby triggering an appropriate immune response. Certain MHC loci are highly polymorphic in humans and other vertebrates, and recent analyses of DNA sequence data have provided evidence that this polymorphism is maintained by positive selection favoring the ability to bind and present a variety of foreign peptides. Therefore the MHC provides an excellent system for studying the evolution of immune recognition and the role of infectious disease as an agent of natural selection. The methods will involve statistical analysis of published DNA sequences, of which there are a large number now available for MHC genes of several mammalian species; for other immune system genes; and for genes of parasites encoding immunogenic proteins. The purpose of these analyses will be as follows: (10 to test the hypothesis that polymorphism at MHC loci is maintained by overdominant selection relating to disease resistance and to understand the role of recombination in generating new MHC alleles; (2) to test the hypothesis that the vertebrate immune system has exerted selection on proteins of parasitic organisms to evade recognition by the host; and (30 to understand the evolutionary history and patterns of co-evolution of MHC genes and other genes playing important roles in the immune system (including T cell receptors, integrins, Fc receptors, the C3/C4/C5 complement component family, and the ABC family of transmembrane transporters). GRANTS=R01HL51630 Alveolar Macrophages (AM) are the first line of cellular defense against inhaled infectious agents such as MTB. Yet almost nothing is known about the capacity of AM from healthy or TB patients to ingest and inhibit the growth of MTB. Our preliminary data indicate that the effector function of AM for avirulent MTB exceeds that of blood monocytes (MN), in part because of increased release of tumor necrosis factor-alpha (TNF) which serves as a macrophage activating factor (MAF). By contrast, AM are weak producers of transforming growth factor beta (TGFbeta), a deactivating cytokine. Mononuclear phagocytes in tuberculous granulomas, however, express TGFbeta, as do MN from TB patients. AM from healthy subjects are primed for effector function against MTB, but TB may be associated with release of deactivating cytokines such as TGFbeta. AM from healthy subjects nonspecifically suppress T lymphocyte responses to antigenic and mitogenic and mitogenic stimuli. During TB, MN specifically suppress T cell responses to tuberculin purified protein derivative (PPD) possibly through increased TGFbeta which is immunosuppressive. Also during TB, peripheral blood mononuclear cells (PBMC) are nonresponsive to the secreted 30 Kd antigen (alphaag) of MTB; as the alphaag is a direct stimulus for cytokine production by MN, this unresponsiveness may be due to cytokine-induced suppression by MN. These considerations lead us to the hypothesis that in TB, AM are specifically suppressive of T cell responses to PPD (and the alphaag) and deactivated for killing of the organism through increased expression of cytokines such as TGFbeta. Together, and separately, immunosuppression and decreased effector function contribute to the pathogenesis of TB in the lung. TB afflicts HIV-infected persons early in their course while tuberculin skin tests are still positive and CD4 counts relatively intact suggesting that disturbances in effector function against MTB may be operant. We hypothesize that these AM are defective in killing of MTB due to increased expression of deactivating cytokines which override MAFs. Th1- type cytokines are protective in certain animal models. We hypothesize that in TB granulomas, macrophages express deactivating cytokines such as TGFbeta and T cells fail to optimally express a Thi-type pattern of cytokines. In TB granulomas from HIV=-infected persons, the cellular architecture is distorted with a further decrease in Th1-type cytokines produced by T cells; concurrent production of deactivating cytokines by mononuclear phagocytes leads to an inexorable increase in load of AFB within granulomas. The Specific Aims to test these hypotheses are: 1. To examine the immunosuppressive activity and mediators of suppression of AM from patients with pulmonary TB for blood T cell responses to tuberculin PPD and the alphaag; and to compare alveolar and blood lymphocyte responsiveness to these stimuli including production of Th1 and Th2 cytokines, and their respective cytotoxicity for antigen-pulsed and MTB-infected AM. 2. To assess the intracellular growth of virulent MTB in AM from patients with TB; their production of and response to macrophage activating and deactivating cytokines; and the modulatory effects of HIV infection. 3. To characterize the cellular architecture and the pattern of cytokine expression in pulmonary granulomas from patients with TB with or without HIV using the complementary approaches of immunofluorescence. RNA PCR, in situ hybridization, and immunohistochemistry.

脊椎动物免疫系统包括许多相互作用的蛋白参与了寄生生物的识别和消除。这这项研究的一般目标是了解密钥的演变该系统的分子成分，尤其是编码的分子由主要的组织相容性复合物（MHC），并了解寄生生物的免疫原性蛋白在天然下进化宿主的免疫系统采取的选择。 MHC是多基因游戏编码在重要作用的细胞表面糖蛋白在免疫系统中，将外肽结合并将其呈现给T 细胞，从而触发适当的免疫反应。某些MHC 基因座在人类和其他脊椎动物中是高度多态的，最近 DNA序列数据的分析提供了证据表明通过积极的选择有利于能力的能力来维持多态性结合并呈现各种外肽。因此MHC 提供了研究免疫进化的绝佳系统识别和传染病作为自然毒剂的作用选择。该方法将涉及已发布的统计分析 DNA序列，其中有大量的MHC可用几种哺乳动物物种的基因；用于其他免疫系统基因；和用于编码免疫原性蛋白的寄生虫基因。目的这些分析将如下：（10检验以下假设： MHC基因座的多态性通过相关的过度选择来维持抗病性并了解重组的作用生成新的MHC等位基因；（2）检验以下假设脊椎动物免疫系统已在寄生的蛋白质上进行选择有机体逃避宿主的认可；（30了解 MHC基因和其他共同进化的进化史和模式基因在免疫系统中起重要作用（包括T细胞受体，整合素，FC受体，C3/C4/C5补体组件家族和ABC跨膜转运蛋白家族）。赠款= R01HL51630 肺泡巨噬细胞（AM）是针对的细胞防御吸入感染剂，例如MTB。但是几乎一无所知从健康或结核病患者摄入并抑制AM的能力 MTB的生长。我们的初步数据表明效应子功能 AM的无毒MTB超过血液单核细胞（MN）的部分由于肿瘤坏死因子-Alpha（TNF）的释放增加了用作巨噬细胞激活因子（MAF）。相比之下，AM很弱转化生长因子β（TGFBETA）的生产商，一种停用细胞因子。然而，结核性肉芽肿的单核吞噬细胞表达TGFBETA，TB患者的MN也是如此。来自健康的受试者是针对MTB进行效应函数启动，但TB可能与释放失活细胞因子，例如TGFBETA。来自健康受试者非特异性抑制对抗原和抗原的T淋巴细胞反应有丝分裂和有丝分裂刺激。在结核病期间，MN专门抑制T 细胞对结核蛋白纯化蛋白衍生物（PPD）的反应可能通过增加免疫抑制的TGFBETA。同样在结核病期间外周血单核细胞（PBMC）对 MTB的分泌30 kd抗原（Alphaag）；因为alphaag是直接的 MN生产细胞因子的刺激，这种无反应性可能应到期通过Mn诱导细胞因子诱导的抑制。这些考虑使我们进入 TB中AM特别抑制T细胞的假设对PPD（和alphaag）的反应，并停用杀害通过增加TGFBETA等细胞因子表达的生物体。一起，分别，免疫抑制和降低效应子功能有助于肺中结核病的发病机理。结核病折磨结核蛋白皮肤测试的早期艾滋病毒感染者仍然是积极的，CD4计数相对完整，表明针对MTB的效应函数的干扰可能是操作者。我们假设这些AM由于覆盖MAF的失活细胞因子的表达增加。 th1- 类型的细胞因子在某些动物模型中具有保护性。我们假设在结核病肉芽肿中，巨噬细胞表达失活细胞因子这样由于TGFBETA和T细胞无法最佳地表达细胞因子。在来自HIV =感染者的结核病肉芽肿中，细胞架构被扭曲，Th1型细胞因子进一步降低由T细胞产生；同时产生失活细胞因子单核吞噬细胞导致AFB负载无法增加在颗粒中。检验这些假设的具体目的是：1。检查免疫抑制活性和抑制介质肺结核患者的AM用于血液T细胞的反应结核蛋白PPD和αAg；并比较牙槽和血液淋巴细胞对这些刺激的反应性，包括产生Th1 和Th2细胞因子及其各自的抗原粉末细胞毒性和MTB感染的AM。 2。评估有毒的细胞内生长 TB患者的AM中的MTB；他们的产生和对巨噬细胞激活和失活细胞因子；和调节艾滋病毒感染的影响。 3。表征蜂窝结构以及肺肉芽肿的细胞因子表达的模式使用互补方法有或没有HIV的结核病患者免疫荧光。 RNA PCR，原位杂交和免疫组织化学。