HIV Evasion of NK Cells in Lymph Nodes

描述（由申请人提供）：HIV感染的主要部位是淋巴结。尽管存在淋巴细胞，如自然杀伤细胞（NK），可以潜在地控制HIV感染，但HIV复制在这个组织室中是稳健的。更有趣的是，强大的病毒复制发生在促进NK细胞杀伤活性的环境下，例如：1)细胞因子（即IL-2、-12和-15）水平升高，它们增强NK细胞介导的细胞毒性，促进NK细胞从无NK细胞向效应NK细胞的发展，2)受感染细胞的分子表达减少[例如：向NK细胞提供抑制信号的主要组织相容性分子（MHC） I类分子]（即HLA-A和-B）； 3)感染细胞表达向NK细胞提供激活信号的表面分子（即ulbp）。我们的目的是确定为什么HIV在淋巴结中盛行，尽管环境有利于NK细胞介导的HIV感染细胞的杀伤。我们的假设是，HIV通过以下途径逃避淋巴结中的NK细胞：1)它能够改变淋巴结中NK细胞群的组成，因此它主要由无反应的NK细胞（即CD56negCD16pos）组成；2)它能够降低感染t细胞上触发NK细胞反应的分子（即CD48和NTB-A）的表达，同时保持抑制分子（即HLA-C）的表达。为了验证这一假设，将从HIV感染和未感染的受试者中获得腹股沟淋巴结，分离淋巴样NK细胞，并确定HIV感染个体淋巴结中NK细胞破坏HIV感染细胞的能力。这将首先通过确定淋巴NK细胞杀死感染一株HIV-1SF162的自体外周血CD4pos t细胞的总体细胞毒能力来完成。NK细胞的细胞毒活性将与淋巴结细胞产生的细胞因子水平进行比较。不同淋巴NK细胞亚群的分布也将通过多色流式细胞术确定。此外，我们将通过多色流式细胞术确定NK细胞上的各种抑制和激活受体。此外，将从淋巴结中获得hiv感染的t细胞，并确定这些细胞对自体淋巴样NK细胞的易感性。最后一步将是表征hiv感染细胞表面的各种配体的表达，这些配体与向NK细胞提供阳性和阴性信号的受体结合。我们的预期是，在hiv感染者的淋巴结中，NK细胞将具有受损的细胞毒性，并且受感染的淋巴样t细胞将对NK细胞产生抗性，因为同时保留了抑制分子和激活分子在受感染细胞表面的表达减少。这项研究的发现将为HIV逃避淋巴结NK细胞的机制提供见解。反过来，这些见解将为研究能够增强艾滋病毒免疫控制的新治疗策略提供理论依据。公共卫生相关性：该项目将确定艾滋病毒如何逃避淋巴结中称为自然杀伤细胞的免疫细胞，这是艾滋病毒感染的主要部位。这项研究的结果将为艾滋病毒避免免疫系统检测和破坏的机制提供见解。这些见解将为提高免疫系统控制艾滋病毒的能力的治疗策略指明道路。

DESCRIPTION (provided by applicant): A major site for productive HIV infection is the lymph node. HIV replication is robust in this tissue compartment despite the presence of lymphocytes such as natural killer (NK) cells that can potentially control HIV infection. Even more intriguing is the fact that robust viral replication takes place under circumstances that promote NK cell killing activity such as 1) the presence of elevated levels of cytokines (i.e., IL-2, -12 and -15) which enhance NK cell mediated cytotoxicity and promote the development of effector NK cells from na¿ve NK cells, 2) the decreased expression by infected cells of molecules [e.g., major histocompatibility molecules (MHC) class I molecules] that provide inhibitory signals to NK cells (i.e., HLA-A and -B) and, 3) the expression by infected cells of surface molecules that provide activating signals to NK cells (i.e., ULBPs). Our objective is to determine why HIV prevails in lymph nodes despite an environment that favors NK cell mediated killing of HIV infected cells. Our hypothesis is that HIV evades NK cells in the lymph node through 1) its ability to alter the makeup of the NK cell population in the lymph node so it consists mostly of unresponsive NK cells (i.e., CD56negCD16pos), and 2) its ability to decrease the expression of molecules on infected T-cells that trigger NK cell responses (i.e., CD48 and NTB-A) while maintaining the expression of inhibitory molecules (i.e., HLA-C). To test this hypothesis, inguinal lymph nodes will be obtained from HIV-infected and uninfected subjects, lymphoid NK cells will be isolated and the capacity of NK cells in the lymph node of HIV-infected individuals to destroy HIV infected cells will be determined. This will initially be accomplished by determining the overall cytotoxic capability of lymphoid NK cells to kill autologous peripheral blood CD4pos T-cells infected with a primary strain HIV-1SF162. The cytotoxic activity of NK cells will be compared with the levels of cytokines produced by cells in the lymph nodes. The distribution of the different lymphoid NK cell subsets will also be determined by multicolor flow cytometry. Moreover we will determine the various inhibitory and activating receptors on NK cells by multicolor flow cytometry. In addition, HIV-infected T-cells will be obtained from lymph nodes and the susceptibility of these cells to autologous lymphoid NK cells will be determined. The final step will be to characterize the expression on HIV-infected cell's surface of various ligands that bind to receptors that provide positive and negative signals to NK cells. Our expectation is that in the lymph node of HIV-infected individuals, NK cells will have impaired cytotoxicity and that infected lymphoid T-cells will be resistant to NK cells because of the simultaneous retention of inhibitory molecules and the decreased expression of activating molecules on the infected cell surface. The findings from this study will provide insights into the mechanisms by which HIV evades NK cells in lymph nodes. These insights, in turn, will provide the rationale for investigating new treatment strategies that can enhance the immune control of HIV. PUBLIC HEALTH RELEVANCE: This project will determine how HIV evades immune cells called natural killer cells in the lymph nodes, which is a major site for productive HIV infection. The results from this study will provide insights on the mechanisms by which HIV avoids detection and destruction by the immune system. These insights will point the way towards treatment strategies that will enhance the immune system's ability to control HIV.