Tregs, Gut Microbiome and Immune Responses in HIV-Exposed and Unexposed Infants

摘要 婴儿严重感染的发生率高，对疫苗的免疫反应低。暴露于艾滋病病毒 未感染婴儿(HEU)的严重感染、住院和死亡的发生率甚至比 未接触艾滋病毒的未感染婴儿(HUU)和对疫苗的较低反应。我们假设全球 HEU的免疫功能障碍是由于1)高度炎症反应而产生的过量Tregs所致 宫内环境中感染HIV的孕妇和2)婴儿肠道生物失调。这些假设将是 具体目标如下： 目的1.测量HEU和HU中Tregs在出生第一年的比例并确定 Tregs的丰度与对活疫苗的免疫反应降低之间的相关性。 这将通过比较100个HEU和100个HEU在出生时、6个月和1岁时的Treg亚群来实现 来自南非索韦托的100个HUU，并通过关联主要Treg子集的频率(测量 流式细胞术)与卡介苗的细胞免疫应答(ELISPOT法)和它们的 对麻疹疫苗的抗体反应(用酶联免疫吸附试验测定)。这两种疫苗都是减毒活疫苗，因此 产生模仿野生型感染反应的免疫反应。 目的2.确定HEU和HUU之间肠道微生物区系组成和多样性的差异， 它们与Treg亚群及其对疫苗的反应有关。肠道微生物区系具有显著的 对免疫系统的发育，特别是对Tregs的影响是公认的。我们会 通过高通量16S rRNA测序比较HEU和HUS的微生物群，并将进行调查 与Treg亚群和疫苗免疫反应的相关性。 目的3.比较HEU和HUU对Treg分化和功能至关重要的表观遗传学特征。拿走 优势是，有一些已知的关键位点的甲基化状态决定了Treg的分化，我们将 比较HEU和HUS中的这些地区。 这些目标的完成将开启间接教育新生儿免疫系统的可能性 调节婴儿和/或母亲肠道微生物群和/或设计抗Tregs疫苗。

Summary Infants have a high incidence of severe infections and low immune responses to vaccines. HIV-exposed uninfected infants (HEUs) have even higher incidence of severe infections, hospitalizations and death than HIV-unexposed uninfected infants (HUUs) and lower responses to vaccines. We hypothesized that the global immune dysfunction of HEUs results from excessive Tregs that develop in response to 1) a highly inflammatory in utero environment of HIV-infected pregnant women and 2) infant gut dysbiosis. These hypotheses will be addressed in the following Specific Aims: AIM 1. To measure the proportions of Tregs in HEUs and HUUs during the 1st year of life and to identify correlations between the abundance of Tregs and decreased immune responses to live vaccines. This will be accomplished by comparing the Treg subsets at birth, 6 months and 1 year of life of 100 HEUs and 100 HUUs from Soweto, South Africa, and by correlating the frequency of dominant Treg subsets (measured by flow cytometry) with the cellular immune responses to BCG vaccine (measured by ELISPOT) and with their antibody responses to measles vaccine (measured by ELISA). Both vaccines are live attenuated and therefore generate immune responses that mimic the responses to wild type infections. AIM 2. To identify differences in the composition and diversity of the gut microbiota between HEUs and HUUs, which are associated with Treg subsets and their responses to vaccines. The gut microbiota have a prominent and well-established effect on the development of the immune system and on Tregs in particular. We will compare the microbiomes of HEUs and HUUs by high throughput sequencing of 16S rRNA and will investigate correlations with Treg subsets and immune responses to vaccines. AIM 3. To compare the HEU and HUU epigenetic profiles critical for Treg differentiation and function. Taking advantage that there are known key sites whose methylation status determines Treg differentiation, we will compare these regions in HEUs and HUUs. The completion of these Aims will open the possibility of indirectly educating the neonate immune system by modulating the infant and/or maternal gut microbiomes and/or by designing vaccines resistant to Tregs.