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

描述(由申请人提供)：急性HIV感染伴随着炎症和胃肠道(GI)中CD4T细胞的严重丧失。由肠道引起的全身性炎症现在被认为是艾滋病毒/艾滋病进展的致病因素。我们假设，在急性感染的情况下，转向Th17反应而不是促炎的Th1反应将是保护性的。我们发现转录因子T-bet在体内控制着Th1/Th17的平衡，既是Th1分化的激活因子，也是Th17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实际上可能对急性感染艾滋病毒的患者有害，因为它增强了肠道中促炎症的Th1反应。值得注意的是，还有其他理由相信沉默T-bet将在急性艾滋病毒感染的环境中起到保护作用。首先，T-bet是CD4和CD8T细胞中IL-2的抑制因子，这种细胞因子已被证明与精英控制者人群中较低的病毒载量有关。其次，T-bet-/-CD4细胞是多功能的，即“多种细胞因子分泌”，这是最近与病毒控制有关的一种表型。我们认为，减少T-bet的表达将1)增加肠道保护性Th17细胞；2)减少促炎症Th1驱动的反应，如巨噬细胞激活；3)增加CD8细胞T反应所必需的IL-2的产生；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模型为对抗逆转录病毒的免疫反应提供了有价值的见解，并将使我们能够轻松地测试T-bet缺失和T-bet过表达的效果。然而，它与人类艾滋病毒/艾滋病只有部分相似之处。如果我们在MAIDS模型中的原则证明实验是令人鼓舞的，我们将迅速转移到更相关的模型，一个被称为BLT的人源化小鼠模型，以询问1)T-bet沉默在人体细胞中是否提供了对体内艾滋病毒的保护，以及2)T-bet过度表达是否会加剧急性HIV感染。根据我们在MAIDS模型中的结果，将慢病毒T-bet siRNAs和T-bet cDNAs转导到人HSCs，用于过继转移实验到BLT小鼠。因此，这项建议的目标是进一步探索我们实验室分离的转录激活/抑制因子在HIV免疫反应中的功能和作用机制。正是基于强大的初步数据，T-bet控制Th1细胞的发育和功能，并抑制IL-17和IL-2产生细胞的发育。重点将放在该基因及其产物在急性艾滋病毒感染以及最终产生对艾滋病毒的持久保护性免疫中的作用。 与公共卫生相关：现在认为肠道引起的全身性炎症是急性艾滋病毒/艾滋病进展的致病因素。我们发现，转录因子T-bet在体内控制着Th1/Th17的平衡，既是Th1分化的激活剂，也是Th17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Th1反应。我们将测试这一假设，即阻断T-bet表达将1)增加肠道保护性Th17细胞2)减少促炎Th1驱动的反应3)增加CD8细胞T反应所需的IL-2的产生4)增加多功能T细胞的数量和5)将缓解两种不同的艾滋病小鼠模型的急性疾病：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.