Role Of Innate Immunity In The Initiation And Pathogenes

先天免疫在起始和病原体中的作用

• 批准号: 7303860
• 负责人: Shyamasundaran Kottilil
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7303860
• 关键词: Role; Innate; Immunity; Initiation; Pathogenes

Innate immunity is the first line of defense designed to protect the host from invading pathogens, including HIV. We have previously described several NK cell dysfunctions in HIV-viremic individuals. In the past year, investigated the effect of HIV envelope glycoproteins (gp120) on the physiologic functions of NK cells. Upon treatment of NK cells with HIV gp120, DNA microarray analyses indicated up regulation of several categories of genes that are associated with apoptosis and suppression of both cellular proliferation and survival, as well as down regulation of genes that play a vital role in cell proliferation, innate immune defense mechanism, and cell survival. Each of two subtypes of gp120, which bind to either the CXCR4 or CCR5 co-receptor, suppressed NK cell cytotoxicity, proliferation and ability to secrete interferon-?. NK cells exposed to X4-subtype HIV gp120 showed a significant decrease in the levels of CC-chemokines, while exposure to R5-subtype HIV gp120 had minimal effect. Extended exposure to HIV gp120 resulted in apoptosis of NK cells, further validating the microarray data. Our data demonstrate that exposure of NK cells to HIV envelope proteins results in profound cellular abnormalities at the level of gene expression as well as generic cell functions. These findings are likely to be a consequence of a direct HIV gp120-mediated effect on NK cells. Identification of specific surface receptors on NK cells that interact with HIV envelope proteins might explain how HIV is capable of circumventing innate immune defense mechanisms and establishing infection in susceptible individuals. We also performed DNA microarray analyses as well as phenotypic and functional analyses using NK cells from HIV-infected individuals in an effort to elucidate the mechanisms by which ongoing HIV replication affects the physiologic function of these cells. Genetic profiles (DNA microarray) and phenotypic and functional characteristics of NK cells isolated from HIV-infected viremic and aviremic, as well as HIV-seronegative individuals, were compared. More than 100 genes were shown to be up-regulated in NK cells from HIV-infected viremic individuals when compared to those from HIV-infected aviremic and HIV-negative individuals. Several of those genes belong to the immune response and apoptosis gene families. Functional assays confirmed an increased propensity of NK cells from HIV viremic individuals to undergo Fas-mediated apoptosis (FMA). Furthermore, increased expression of CD95 on NK cells of HIV-infected viremic individuals was associated with increased susceptibility to undergo FMA, but not CD16- or NKG2D-mediated apoptosis. Serum levels of sFasL and expression of Ki67 on NK cells were markedly elevated in HIV-infected viremic individuals when compared to those of HIV-infected aviremic and HIV-negative individuals. Our data demonstrate that ongoing HIV replication results in profound NK cell abnormalities that are likely to be due to the effects of virus-induced immune activation. Of note is an increased susceptibility to cell-death mediated by CD95-sFasL interactions. In addition, these NK cells, particularly the CD56dim CD16bright subset, undergo enhanced cell turn-over in vivo as demonstrated by intracellular Ki67 expression.

先天免疫是旨在保护宿主免受包括艾滋病毒在内的病原体入侵的第一道防线。我们之前已经描述了 HIV 病毒血症个体中的几种 NK 细胞功能障碍。去年，研究了HIV包膜糖蛋白（gp120）对NK细胞生理功能的影响。用 HIV gp120 处理 NK 细胞后，DNA 微阵列分析表明，与细胞凋亡和抑制细胞增殖和存活相关的几类基因的上调，以及在细胞增殖中发挥重要作用的基因的下调，先天免疫防御机制和细胞存活。 gp120 的两种亚型均与 CXCR4 或 CCR5 辅助受体结合，抑制 NK 细胞的细胞毒性、增殖和分泌干扰素-β的能力。暴露于 X4 亚型 HIV gp120 的 NK 细胞显示 CC 趋化因子水平显着下降，而暴露于 R5 亚型 HIV gp120 的影响最小。长期暴露于 HIV gp120 会导致 NK 细胞凋亡，进一步验证了微阵列数据。我们的数据表明，NK 细胞暴露于 HIV 包膜蛋白会导致基因表达水平以及一般细胞功能的严重细胞异常。这些发现很可能是 HIV gp120 介导的对 NK 细胞的直接影响的结果。鉴定 NK 细胞上与 HIV 包膜蛋白相互作用的特定表面受体可能解释 HIV 如何能够绕过先天免疫防御机制并在易感个体中建立感染。 我们还使用来自 HIV 感染者的 NK 细胞进行了 DNA 微阵列分析以及表型和功能分析，以努力阐明持续的 HIV 复制影响这些细胞的生理功能的机制。比较了从 HIV 感染者和无病毒血症者以及 HIV 血清阴性个体中分离出的 NK 细胞的遗传特征（DNA 微阵列）以及表型和功能特征。与感染 HIV 的无病毒血症和 HIV 阴性个体的 NK 细胞相比，感染 HIV 的病毒血症个体的 NK 细胞中有 100 多个基因上调。其中一些基因属于免疫反应和细胞凋亡基因家族。功能分析证实，HIV 病毒血症个体的 NK 细胞发生 Fas 介导的细胞凋亡 (FMA) 的倾向增加。此外，HIV感染者的NK细胞上CD95表达增加与FMA易感性增加相关，但与CD16或NKG2D介导的细胞凋亡无关。与感染 HIV 的无病毒血症和 HIV 阴性个体相比，感染 HIV 的病毒血症个体的 sFasL 血清水平和 NK 细胞上 Ki67 的表达显着升高。我们的数据表明，持续的 HIV 复制会导致 NK 细胞严重异常，这可能是由于病毒诱导的免疫激活的影响所致。值得注意的是 CD95-sFasL 相互作用介导的细胞死亡敏感性增加。此外，这些 NK 细胞，特别是 CD56dim CD16bright 子集，在体内经历增强的细胞更新，如细胞内 Ki67 表达所证明的。