Understanding Th-monocyte interactions in HIV infection

项目概要/摘要： 在发现艾滋病病毒30多年后，仍然没有预防艾滋病病毒的疫苗或杀微生物剂 感染抗逆转录病毒疗法（ART）成功地抑制了病毒复制，但它不能清除病毒。 病毒，只提供部分免疫恢复，需要终身坚持。更好地了解 开发预防HIV感染的新策略需要基本的HIV-宿主细胞相互作用。这一拟议 一项研究试图调查艾滋病毒与抗原呈递细胞（APC）和辅助性CD 4 T（Th）的相互作用 在抗HIV抗体（Abs）存在的情况下，抑制病毒向Th细胞的扩散。 CD 4 Th细胞是HIV感染的主要细胞类型，但并非所有Th细胞都同样脆弱。作为 与Th 1细胞相比，Th 17细胞优先被HIV靶向，部分原因是HIV的更高表达 包膜（Env）受体，包括α4β7。我们最近的研究表明，Th 17细胞也优先 由APC传播的艾滋病毒的目标。然而，艾滋病毒与Th细胞的相互作用产生了不同的结果， 和不同的APC。HIV暴露的单核细胞有效地将病毒传递给Th 17细胞，同时刺激Th细胞 增殖，导致感染的Th 17细胞数量的扩增。相比之下， HIV暴露的单核细胞衍生的树突状细胞（MDDC）导致Th 17细胞数量下降。此外，本发明还 我们观察到在Th细胞与APC之间的免疫突触中，HIV Env增强Th细胞 通过像共刺激分子一样起作用来激活。因此，共刺激的Th细胞变得对HIV更宽容 感染 HIV Env是调节病毒向Th细胞传播和靶细胞活化的关键决定因子 Th细胞。HIV传播取决于Env共受体向性（CCR 5 vs CXCR 4），并且对 抗Env Ab的干扰。HIV诱导的Th细胞活化的增强也由Env触发， 被抗Env抗体抑制。基于这些发现，我们建议进一步研究HIV Env 影响病毒从APC向Th细胞传播效率的决定因素。我们的假设是艾滋病毒 利用APC和Th细胞之间的密切细胞-细胞接触来扩散到Th细胞， 细胞活化，通过病毒Env的作用使它们更允许病毒复制。 因此，抗Env Ab通过与HIV病毒体形成免疫复合物，可以改变APC-Th细胞相互作用， 使病毒传播和复制变钝。 为了验证这些假设，在目标1中，我们将定义HIV Env决定因素，这些决定因素对于有效的HIV感染至关重要。 从APC到Th细胞的传递。用HIV处理的单核细胞和MDDC将作为APC在共- 培养系统，刺激Th 1和Th 17细胞，并以不同的Env.环境变量为 评价包括共受体使用、N-聚糖组成以及对α4β7和甘露糖结合的亲和力 受体。目的二是评价抗Env单克隆抗体对病毒从APCs向Th细胞传播的阻滞作用。 我们将测试针对不同表位的中和性和非中和性单克隆抗体，以及多克隆抗体。 由Env表位靶向疫苗产生。还将评估Ab的Fc介导的活性。最后在 目的3：利用人源化小鼠模型，在体内检测HIV从APC的传播。抗Env Ab， 还将在小鼠模型中评价体外抑制活性。这些实验将产生 这些数据为今后开发更有效的艾滋病毒预防剂提供了信息。

Project Summary/Abstract: More than 30 years after the discovery of HIV, there are still no vaccines or microbicides to prevent HIV infection. Antiretroviral therapy (ART) is successful in suppressing virus replication, but it does not clear the virus, offers only partial immunologic recovery, and requires lifelong adherence. A better understanding of basic HIV–host cell interactions is needed to develop new strategies to prevent HIV infection. This proposed study seeks to investigate the interplay of HIV with antigen-presenting cells (APCs) and helper CD4 T (Th) cells in the presence of anti-HIV antibodies (Abs) that retard virus spread to Th cells. CD4 Th cells are the main cell type infected by HIV, but not all Th cells are equally vulnerable. As compared with Th1 cells, Th17 cells are preferentially targeted by HIV, in part due to higher expression of HIV envelope (Env) receptors, including α4β7. Our recent studies showed that Th17 cells are also preferentially targeted by HIV transmitted from APCs. However, different outcomes arise from HIV interactions with Th cells and distinct APCs. HIV-exposed monocytes efficiently transmit virus to Th17 cells while stimulating Th proliferation, resulting in expansion in the number of infected Th17 cells. In contrast, virus transmission from HIV-exposed monocyte-derived dendritic cells (MDDCs) causes the number of Th17 cells to decline. Further, we observed that in the immunological synapses between Th cells and APCs, HIV Env enhances Th cell activation by acting like a co-stimulatory molecule. Th cells thus co-stimulated become more permissive to HIV infection. HIV Env is the key determinant that regulates virus transmission to Th cells and cellular activation of target Th cells. HIV transmission varies depending on Env co-receptor tropisms (CCR5 vs CXCR4) and is sensitive to interference by anti-Env Abs. HIV-induced enhancement of Th cell activation also is triggered by Env and suppressed by anti-Env Abs. On the basis of these findings, we propose to further investigate the HIV Env determinants influencing the efficiency of virus transmission from APCs to Th cells. Our hypothesis is that HIV utilizes the intimate cell-cell contact between APCs and Th cells to spread to Th cells and also to enhance Th cell activation, rendering them more permissive for virus replication, through the action of the virus Env. Therefore, anti-Env Abs, by forming immune complexes with HIV virions, may alter APC-Th cell interactions to blunt virus transmission and replication. To test these hypotheses, in Aim 1, we will define HIV Env determinants that are essential for efficient transmission from APCs to Th cells. Monocytes and MDDCs treated with HIV will be tested as APCs in a co- culture system to stimulate Th1 and Th17 cells and transmit viruses with distinct Envs. The Env variables to be evaluated include co-receptor usage, N-glycan sugar composition, and affinity for α4β7 and mannose-binding receptors. Aim 2 is to evaluate the ability of anti-Env Abs to retard virus transmission from APCs to Th cells. We will test neutralizing and nonneutralizing monoclonal Abs specific for distinct epitopes, and polyclonal Abs generated by Env epitope-targeted vaccines. Fc-mediated activities of the Abs will also be assessed. Finally, in Aim 3, we will test HIV transmission from APCs in vivo, using the humanized mouse model. Anti-Env Abs with inhibitory activity in vitro will also be evaluated in the mouse model. The proposed experiments will generate data to inform future development of more effective prophylactic agents against HIV.