HIV Evasion of NK Cells in Lymph Nodes

描述（由申请人提供）：生产性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（NK）细胞，可以潜在地控制HIV感染，但HIV复制在该组织区室中是稳健的。甚至更有趣的是，在促进NK细胞杀伤活性的情况下发生稳健的病毒复制，例如1）存在升高水平的细胞因子（即，IL-2、IL-12和IL-15），其增强NK细胞介导的细胞毒性并促进效应NK细胞从幼稚NK细胞的发育，2）感染细胞的分子表达降低[例如，主要组织相容性分子（MHC）I类分子]，其向NK细胞提供抑制信号（即，HLA-A和-B）和，3）受感染细胞表达向NK细胞提供激活信号的表面分子（即，ULBP）。我们的目标是确定为什么HIV在淋巴结中流行，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通过以下方式逃避淋巴结中的NK细胞：1）其改变淋巴结中NK细胞群体的组成的能力，因此其主要由无反应的NK细胞组成（即，CD 56 + CD 16阳性），和2）其降低感染的T细胞上触发NK细胞应答的分子表达的能力（即，CD 48和NTB-A），同时维持抑制性分子（即，HLA-C）。为了检验这一假设，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NK细胞，并测定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细胞杀死感染原代毒株HIV-1 SF 162的自体外周血CD 4pos T细胞的总体细胞毒性能力来实现。将NK细胞的细胞毒性活性与淋巴结中细胞产生的细胞因子水平进行比较。还将通过流式细胞术测定不同淋巴NK细胞亚群的分布。此外，我们还将通过流式细胞术测定NK细胞上的各种抑制性和活化性受体。此外，将从淋巴结获得HIV感染的T细胞，并确定这些细胞对自体淋巴NK细胞的易感性。最后一步将是表征HIV感染细胞表面各种配体的表达，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感染个体的淋巴结中，NK细胞的细胞毒性将受损，并且感染的淋巴T细胞将对NK细胞具有抗性，因为同时保留抑制分子和降低感染细胞表面上的活化分子的表达。这项研究的发现将为HIV逃避淋巴结中NK细胞的机制提供见解。反过来，这些见解将为研究可以增强艾滋病毒免疫控制的新治疗策略提供理论基础。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，淋巴结是艾滋病毒感染的主要场所。这项研究的结果将为HIV避免被免疫系统检测和破坏的机制提供见解。这些见解将为增强免疫系统控制艾滋病毒的能力的治疗策略指明方向。

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.