Restoring HIV-1 Specific T cell Immunity

描述（由申请人提供）：HIV-1特异性T细胞反应最初是有效的，但面对HIV-1改变其序列和逃避免疫压力的惊人能力，CD4 T细胞帮助和慢性抗原的损失，反应变得“耗尽”，不再能够控制HIV-1复制。克服或逆转T细胞衰竭可能是任何成功的HIV-1免疫疗法的重要组成部分，但目前尚不清楚如何做到这一点。我们建议开发并结合两种令人兴奋的方法来恢复HIV-1特异性免疫。第一种方法是使用高亲和力的HIV-1特异性TCRs将免疫反应转向HIV-1。这种方法有可能重置HIV-1特异性衰竭时钟，并重新建立对HIV-1复制的控制。我们的初步数据表明，高亲和力的tcr赋予了更明显的多功能T细胞反应，以低效效比控制HIV-1复制的能力，以及识别常见sl9逃逸突变体的能力。在这里，我们建议将这些研究扩展到体内模型和机制研究。第二种方法是通过靶向PD-1表达，使这些HIV-1特异性T细胞抵抗衰竭分化途径。为此，我们将使用锌指核酸酶永久破坏PD-1的表达。这种方法相对于系统递送阻断抗体的优势在于，PD-1表达的丧失仅限于被输注的HIV-1特异性T细胞。因此，自身免疫的可能性降低。我们建议通过三个相关和协调的特异性目标来实现重振HIV-1特异性免疫应答的目标：1)开发和表征PD-1特异性的先导ZFN；确定PD-1缺乏如何影响HIV-1特异性T细胞反应；3)进行体内临床前实验，确定PD-1缺陷的HIV-1特异性T细胞是否在控制HIV-1复制方面具有优势。这些研究将为在人体中测试这种方法提供基础和理论依据，并有望导致在没有HAART的情况下成功控制HIV-1复制的临床工具。

DESCRIPTION (provided by applicant): The HIV-1 specific T cell response is initially effective but in the face of HIV-1's phenomenal ability to alter its sequence and escape from immune pressure, loss of CD4 T cell help and chronic antigen, the response becomes "exhausted" and no longer can longer control HIV-1 replication. Overcoming or reversing T cell exhaustion is likely going to be an important part of any successful HIV-1 immunotherapy, but how to do this is currently not clear. We propose to develop and combine two exciting approaches to restore HIV-1 specific immunity. The first involves using high affinity HIV-1 specific TCRs to redirect the immune response toward HIV-1. This approach has the potential to reset the HIV-1 specific exhaustion clock and to re-establish control of HIV-1 replication. Our preliminary data indicates the high affinity TCRs confer a more pronounced polyfunctional T cell response, the ability to control HIV-1 replication at low effector to target ratios and the ability to recognize common SL9-escape mutants. Here, we propose to extend these to studies to in vivo models and mechanistic studies. The second approach is to render these HIV-1 specific T cells resistant to the exhaustion differentiation pathway by targeting PD-1 expression. To do this we will use zinc finger nucleases to permanently disrupt PD-1 expression. The advantage of this approach over the systematic delivery of blocking Abs is that loss of PD-1 expression is restricted to the HIV-1 specific T cells that are being infused. Thus, the potential for autoimmunity is reduced. We propose to achieve our goal of reinvigorating the HIV-1 specific immune response through three related and coordinated specific aims: 1) Develop and characterize a lead PD-1 specific ZFN; 2 Determine how PD-1 deficiency affects the HIV-1 specific T cell response; 3) Perform in vivo, pre-clinical experiments to determine whether PD-1 deficient HIV-1 specific T cells are superior at controlling HIV-1 replication. These studies will provide the basis and rationale to test this approach in humans and hopefully lead to clinical tools that successfully control of HIV-1 replication in the absence of HAART.