Prime shock and kill for HIV erradication

项目总结 当人们第一次遇到传染病或疫苗时，他们会产生一种免疫反应 那个试剂或疫苗。一些反应细胞可能会持续数年甚至数十年，成为记忆 T细胞，因此，如果再次遇到感染源，后续的免疫反应可以迅速和 完全正确。由于这些细胞必须持续很长时间，所以它们已经形成了抵抗正常 细胞周转的过程，即这些细胞抵抗死亡信号。艾滋病毒感染是一种慢性的、可控的 到目前为止，由于艾滋病毒在记忆中的CD4T细胞中持续存在而无法治愈的疾病 细胞周转和死亡。在不是记忆CD4T细胞的T细胞中，复制HIV会产生HIV蛋白， 它们是有毒的，会杀死T细胞。矛盾的是，当HIV在记忆的CD4T细胞中重新激活时，这些 HIV蛋白不会杀死细胞。我们认为这些记忆的CD4T细胞在HIV感染后不会死亡的原因是 重新激活，是因为它们对细胞死亡具有内在的抵抗力。相应地，有多个级别的 细胞内的调节，共同决定一个细胞是否会经历细胞死亡。宽泛地说 为了使细胞发生凋亡(一种形式的细胞死亡)，必须满足两个条件：(1)促凋亡者 刺激，以及(Ii)允许的细胞环境，在这种环境中，抗凋亡机制不能阻止 促凋亡信号的传播。 我们的实验室小组研究了HIV是如何导致CD4T细胞死亡的，重点是HIV蛋白酶- Casp8p41途径。在这笔赠款的最后一个资助周期中，我们发现Casp8p41杀死了 细胞通过与促凋亡蛋白Bak结合。相反，如果Casp8p41与抗凋亡蛋白Bcl2结合， 那么，HIV不会杀死一个细胞，而是成为一个持久的、潜伏感染的储藏细胞。我们已经产生了 新的和临床相关的观察结果表明，用Bcl2抑制剂(Ventoclax)拮抗Bcl2会改变 艾滋病毒重新激活后死亡的受感染细胞的数量，从而减少艾滋病毒储存库的大小。同样，我们有 结果表明，Casp8p41被Bcl2结合后，该复合体被多泛素化并被降解 蛋白酶体。因此，使用临床上可用的蛋白酶体抑制剂(Bortezomib或Ixazomib)会导致 Casp8p41的积累，增强了感染细胞的杀伤力，改变了随后死亡的感染细胞的数量 HIV重新激活，并有效地减少了HIV储存库的大小。当前应用程序的重点是 优化这些治疗方法以：(I)测试具有最佳潜伏期的Bcl2拮抗剂的组合- 逆转策略，(2)测试最有希望的组合对淋巴艾滋病毒储存库的影响，以及 (Iii)确定为什么某些但不是所有患者的细胞对bcl2抑制有反应，检验假设 多态，或参与这一途径的关键蛋白的表达差异，在 应答者和无应答者。

PROJECT SUMMARY When people encounter an infectious agent or a vaccine for the first time, they develop an immune response to that agent or vaccine. Some of the respondent cells may persist for years – even decades, becoming memory T cells, so that if the infectious agent is again encountered, the subsequent immune response can be rapid and exact. Since these cells must to persist for long periods, they have developed mechanisms to resist the normal process of cell turnover, i.e., these cells withstand death signals. HIV infection is a chronic, manageable disease that, as yet, cannot be cured due to the persistence of HIV in memory CD4 T cells that are resistant to cell turnover and death. In T cells that are not memory CD4 T cells, replicating HIV produces HIV proteins, which are toxic and kill the T cell. Paradoxically, when HIV is reactivated in memory CD4 T cells, these same HIV proteins do not kill the cell. We believe the reason these memory CD4 T cells do not die after HIV is reactivated, is that they are intrinsically resistant to cell death. Accordingly there are multiple levels of regulation within cells that together determine whether a cell will, or will not undergo cell death. In broad terms in order for a cell to undergo apoptosis (one form of cell death) two conditions must be met: (i) a pro-apoptotic stimulus, and (ii) a permissive cellular environment, where anti-apoptotic machinery does not prevent propagation of the pro-apoptotic signal. Our laboratory group has studied how HIV causes the death of CD4 T cells, focusing on the HIV protease- Casp8p41 pathway. During the course of this grant's last funding cycle, we discovered that Casp8p41 kills cells by binding to the pro-apoptotic protein Bak. Conversely, if Casp8p41 binds the anti-apoptotic protein Bcl2, then HIV does not kill a cell, instead becoming a persistent, latently-infected reservoir cell. We have generated novel and clinically relevant observations that antagonizing Bcl2 with a Bcl2 inhibitor (venetoclax) alters the number of infected cells that die following HIV reactivation, reducing the HIV reservoir size. Similarly, we have shown that after Casp8p41 is bound by Bcl2, the complex is polyubiquitinated and degraded by the proteasome. Consequently, using clinically available proteasome inhibitors (bortezomib or ixazomib) causes accumulation of Casp8p41, enhances infected cell killing, alters the number of dead infected cells following HIV reactivation, and effectively reduces the HIV reservoir size. The focus of the current application is to optimize these treatment approaches to: (i) test combinations of Bcl2 antagonists with optimized latency- reversal strategies, (ii) test the effect of the most promising combinations on the lymphoid HIV reservoir, and (iii) determine why some, but not all, patients cells respond to Bcl2 inhibition, testing the hypothesis that polymorphisms, or differences in expression of key proteins involved in this pathway, differ between responders and nonresponders.