T-bet and the Th1/Th17 balance in Acute HIV infection

描述（由申请人提供）：急性HIV感染伴随炎症和胃肠道（GI）CD 4 + T细胞的大量丢失。由肠道引起的全身性炎症现在被认为是HIV/AIDS进展中的致病因素。我们假设，在急性感染的情况下，向Th 17应答的转变和远离促炎性Th 1应答将是保护性的。我们已经发现，转录因子T-bet在体内既作为Th 1分化的激活因子又作为Th 17分化的抑制因子来控制Th 1/Th 17平衡。因此，与T-bet对大多数病原体的保护作用相反，T-bet实际上可能对急性感染HIV的患者有害，因为它增强了肠道中的促炎性Th 1反应。值得注意的是，还有其他理由相信沉默T-bet在急性HIV感染的情况下具有保护作用。首先，T-bet是CD 4+和CD 8 + T细胞中IL-2的阻遏物，这是一种已显示与精英控制者群体中较低病毒载量相关的细胞因子。第二，T-bet-/-CD 4细胞是多功能的，即“多个亮氨酸分泌”，最近与病毒控制相关的表型。我们认为，减少T-bet表达将1）增加肠道保护性Th 17细胞; 2）减少促炎性Th 1驱动的反应，如巨噬细胞活化; 3）增加功能性CD 8+细胞T反应所必需的IL-2产生; 4）增加多功能T细胞的数量。我们将使用两种不同的艾滋病小鼠模型来建立T-bet在体内的功能。MAIDS模型为针对逆转录病毒的免疫应答提供了有价值的见解，并将使我们能够轻松测试T-bet缺失和T-bet过表达的影响。然而，它与人类艾滋病毒/艾滋病的相似性只是部分的。如果我们在MAIDS模型中的原理验证实验令人鼓舞，我们将迅速转向更相关的模型，即称为BLT的人源化小鼠模型，以询问1）人类细胞中的T-bet沉默是否在体内提供针对HIV的保护，以及2）T-bet过表达是否会加剧急性HIV感染。根据我们在MAIDS模型中的结果，将用慢病毒T-bet siRNA和T-bet cDNA转导人HSC用于BLT小鼠的过继转移实验。因此，本提案的目标是进一步探索在我们实验室中分离的转录激活因子/抑制因子在对HIV的免疫应答中的功能和作用机制。基于强有力的初步数据，T-bet控制Th 1细胞的发育和功能，并抑制产生IL-17和IL-2的细胞的发育。重点将放在该基因及其产物在急性艾滋病毒感染中的作用，并最终产生对艾滋病毒的持久保护性免疫。 公共卫生相关性：现在认为肠道引起的全身性炎症是急性HIV/AIDS进展中的致病因素。我们已经发现，转录因子T-bet控制体内Th 1/Th 17平衡，既作为Th 1分化的激活因子，又作为Th 17分化的抑制因子-因此，与T-bet对大多数病原体的保护作用相反，T-bet实际上可能对感染HIV的患者有害，因为它增强了肠道中的促炎性Th 1应答。我们将测试以下假设：阻断T-bet表达将1）增加肠道保护性Th 17细胞2）减少促炎性Th 1驱动的应答3）增加功能性CD 8+细胞T应答所必需的IL-2产生4）增加多功能T细胞的数量和5）将改善两种不同的AIDS小鼠模型中的急性疾病：MAIDS和BLT人源化小鼠模型。

DESCRIPTION (provided by applicant): Acute HIV infection is accompanied by inflammation and by a profound loss of CD4+ T cells from the gastrointestinal (GI) tract. Systemic inflammation arising from the gut is now thought to be pathogenic in progression of HIV/AIDS. We hypothesize that a shift towards a Th17 response and away from a pro-inflammatory Th1 response in the setting of acute infection will be protective. We have discovered that the transcription factor T-bet controls the Th1/Th17 balance in vivo both as an activator of Th1 differentiation and as a repressor of Th17 differentiation. Hence, in contrast to the protective role of T-bet for most pathogens, T-bet may actually be deleterious for a patient acutely infected with HIV because it enhances a pro-inflammatory Th1 response in the gut. Of note, there are additional reasons to believe that silencing T-bet will be protective in the setting of acute HIV infection. First, T-bet is a repressor of IL-2 in CD4+ and CD8+ T cells, a cytokine which has been shown to correlate with lower viral load in the elite controller population. Second, T-bet-/- CD4 cells are polyfunctional i.e. "multiple cytokine-secreting", a phenotype recently associated with viral control. We suggest that reducing T-bet expression will 1) increase gut protective Th17 cells; 2) reduce pro-inflammatory Th1-driven responses such as macrophage activation; 3) increase IL-2 production necessary for functional CD8+ cell T responses and 4) increase numbers of polyfunctional T cells. We will use two different mouse models of AIDS to establish the function of T-bet in vivo. The MAIDs model has provided valuable insights into the immune response against retroviruses and will allow us to test the effect of T-bet absence and T-bet overexpression easily. However, its resemblance to human HIV/AIDs is only partial. If our proof-of-principle experiments in the MAIDS model are encouraging, we will move quickly to the more relevant model, a humanized mouse model called BLT, to ask whether 1) T-bet silencing in human cells provides protection against HIV in vivo and 2) T-bet overexpression exacerbates acute HIV infection. Guided by our results in the MAIDS model, human HSCs will be transduced with lentiviral T-bet siRNAs and T-bet cDNAs for adoptive transfer experiments to BLT mice. Hence, the goal of this proposal is to further explore the function and mechanism of action of a transcriptional activator/repressor, isolated in our laboratory, in the immune response to HIV. It is based on strong preliminary data that T-bet controls the development and function of Th1 cells and represses the development of IL-17 and IL-2 producing cells. The emphasis will be on the role of this gene and its products in the setting of acute HIV infection and ultimately in the generation of durable protective immunity to HIV. PUBLIC HEALTH RELEVANCE: Systemic inflammation arising from the gut is now thought to be pathogenic in progression of acute HIV/AIDS. We have discovered that the transcription factor T-bet controls the Th1/Th17 balance in vivo both as an activator of Th1 differentiation and as a repressor of Th17 differentiation- hence, in contrast to the protective role of T-bet for most pathogens, T-bet may actually be deleterious for a patient infected with HIV because it enhances a pro-inflammatory Th1 response in the gut. We will test the hypothesis that blocking T-bet expression will 1) increase gut protective Th17 cells 2) reduce pro-inflammatory Th1-driven responses 3) increase IL-2 production necessary for functional CD8+ cell T responses 4) increase numbers of polyfunctional T cells and 5) will ameliorate acute disease in two different mouse models of AIDS: MAIDS and the BLT humanized mouse model.