The Impact of Antiretroviral Therapy on Fetal Immune System Development in SIV-exposed Rhesus Macaques

SCOPE OF WORK More than 1 million HIV-infected pregnant women give birth every year worldwide. The use of antiretroviral therapy (ART) for pregnant and breastfeeding women is an effective way to prevent mother-to-child HIV transmission. However, studies show that the HIV-exposed, but uninfected (HEU) children experience several adverse outcome, including higher mortality from common infections and severe respiratory disease. It has been proposed that the adverse outcomes in HUE children are related to infection-induced maternal inflammation, promoting immune activation in the fetus, and/or ART toxicity throughout the period of in utero development. However, this hypothesis has not been examined mechanistically and the effects of ART on the fetal immune system in the absence of maternal infection have not been elucidated. Distinguishing the effects of HIV and ART in the clinical setting is difficult. Clinical studies are limited by access to tissues and controlling for multiple variables that can modulate immunity. Furthermore, the effects of HIV and ART on the tissue- resident phenotype and functional properties of fetal immune cells remain unknown. Therefore, in this application, we propose to leverage the well-established rhesus macaque model of simian immunodeficiency virus (SIV) to test the hypothesis that maternal SIV and ART exert differential effects on the fetus, resulting in defects in fetal immune system development and immune responses to pathogens. The use of the NHP model allows in depth analysis of the fetal immune system in multiple immune compartments using innovative genomic and functional technologies in a genetically outbred model while controlling for many of the variables that confound clinical studies, thereby providing unique insights into mechanism of fetal immune development. We will study three experimental groups of females. In the SIV/ART group, females will be infected with SIV and then suppressed with ART before undergoing timed mated breeding. We will have two control groups: ART only group and untreated/uninfected healthy pregnancy. Gestational day 135 fetal blood and lymphoid tissues will be obtained following C-section from macaque dams using time-mated breeding approach, which will be used to test this hypothesis in the following two aims: Aim 1. Determine the effects of maternal SIV/ART or ART on fetal immune system function. We will test the hypothesis that maternal SIV/ART leads to increased activation of fetal immune cells at baseline that will be accompanied by dampened responses to stimuli akin to an immune “tolerance”. On the other hand, maternal ART will result in adverse effects in mitochondria leading to impaired immune cell function. Aim 2. Determine the effects of maternal SIV/ART or ART on fetal hematopoiesis. We will test the hypothesis that maternal SIV/ART-driven inflammation will lead to premature activation of fetal HSPCs, resulting in exhaustion. On the other hand, maternal ART will induce mitochondrial toxicity in fetal HSPCs, resulting in impaired differentiation. The Messaoudi laboratory will be responsible for all the omics analyses including single cell RNA-Sequencing and ATAC-Sequencing as well as accompanying bioinformatics analysis. The Messaoudi laboratory will provide guidance and input on the flow cytometry studies. Dr. Messaoudi will play an integral role in the overall direction of the project and the preparation of all reports and manuscripts in accordance with her role as Co-PI.