Role Of Innate Immunity In The Initiation And Pathogenes

先天免疫是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病毒携带者的几种NK细胞功能障碍。在过去的一年里，研究了HIV包膜糖蛋白(Gp120)对NK细胞生理功能的影响。在用HIV gp120处理NK细胞后，DNA微阵列分析表明，与细胞凋亡、抑制细胞增殖和生存相关的几类基因表达上调，而在细胞增殖、天然免疫防御机制和细胞存活中起重要作用的基因表达下调。与CXCR4或CCR5共受体结合的两种gp120亚型中的每一种都能抑制NK细胞的细胞毒性、增殖和分泌干扰素的能力。暴露于X4亚型HIV gp120的NK细胞的CC趋化因子水平显著降低，而暴露于R5亚型HIV gp120的NK细胞对CC趋化因子水平的影响很小。长期接触HIV gp120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和普通细胞功能的严重细胞异常。这些发现很可能是HIV gp120对NK细胞的直接影响的结果。识别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，以努力阐明正在进行的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、病毒携带者和无核者以及HIV血清阴性者分离的NK细胞的基因图谱(DNA芯片)、表型和功能特征。与HIV感染、无病毒和HIV阴性的人相比，HIV感染的病毒症患者的NK细胞中有100多个基因上调。这些基因中有几个属于免疫反应和凋亡基因家族。功能分析证实，来自HIV病毒感染者的NK细胞经历Fas介导的凋亡(FMA)的倾向增加。此外，HIV感染的病毒感染者NK细胞上CD95的表达增加与FMA的易感性有关，但与CD16或NKG2D介导的细胞凋亡无关。HIV感染者的血清sFasL水平和NK细胞Ki67的表达水平明显高于HIV感染者、无病毒者和HIV阴性者。我们的数据表明，正在进行的艾滋病毒复制导致严重的NK细胞异常，这可能是由于病毒诱导的免疫激活的影响。值得注意的是，CD95-sFasL相互作用导致的细胞死亡易感性增加。此外，这些NK细胞，特别是CD56dim CD16bright亚群，在体内经历了增强的细胞翻转，细胞内Ki67的表达证明了这一点。

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.