Influence of Early Life Gut Microbiota of HIV-Exposed Uninfected Infants on Inflammation, Growth and Immunity to Enteric Pathogens

由于获得抗逆转录病毒疗法的机会增加，围产期艾滋病毒传播率大幅下降 在怀孕和哺乳期间。然而，这导致越来越多的婴儿感染艾滋病毒- 暴露但未感染（iHEU）。iHEU显示出增强的炎症、免疫激活和免疫应答。 可能是由于肠道微生物群的改变而导致的疲惫。艾滋病毒暴露也与受损的 婴儿的生长（发育迟缓）。多项研究表明，与艾滋病毒相比，iHEU的发育迟缓 未暴露婴儿（iHU）。此外，营养不良的研究已经将慢性肠道炎症联系起来， 与肠道微生物群改变有关，在婴儿中导致生长受损。受损背后的机制 iHEU的增长不被理解。iHEU中肠道炎症加剧可能与 发育迟缓然而，iHEU中的肠道微生物群是否会导致生长受损尚未得到正式测试。 除了生长，肠道微生物群还影响免疫发育。具体来说，早期的微生物群组成 生命印记的持久免疫后果。iHEU显示出高感染性发病率，包括肠道感染性发病率 病原体例如，研究表明，iHEU表现出肠致病性大肠杆菌的高流行率， 大肠杆菌（EPEC）和隐孢子虫属相比，未暴露的同行。肠道微生物群已经被证明 通过各种机制保护免受肠道病原体的侵害，包括定植抗性和改变 粘膜免疫iHEU中的肠道微生物群是否会增强对肠道病原体的易感性尚不清楚。 人类研究是基于相关性，这限制了推断因果关系的能力。我们将使用无菌新生儿 小鼠模型，以研究iHEU中早期粪便微生物群在驱动这些临床 表型。此外，我们将使用EPEC的新生小鼠模型来测试粪便微生物群之间的因果关系， 和对肠道病原体的免疫力。我们假设，iHEU的肠道微生物群在生命早期导致 炎症、生长不良和损害对肠道病原体的免疫力。我们建议检验这一假设 具体目标如下。 目的1：研究iHEU的早期肠道微生物群是否引起肠道和全身炎症 以及婴儿期的线性生长受损。 目的2：研究iHEU的早期肠道微生物群是否损害对肠道病原体的免疫力

Rates of perinatal HIV transmission have fallen substantially due to increased access to antiretroviral therapy during pregnancy and breastfeeding. However, this has led to a growing population of infants who are HIV- exposed but uninfected (iHEU). iHEU display heightened inflammation, immune activation and immune exhaustion potentially driven by their altered gut microbiota. HIV exposure has also been linked to impaired growth (stunting) in infants. Multiple studies have shown evidence of stunting in iHEU compared to HIV unexposed infants (iHU). In addition, malnutrition studies have linked chronic intestinal inflammation, which also associated with gut microbiota alteration, in infants to impaired growth. The mechanism(s) behind impaired growth in iHEU are not understood. It is plausible that heightened intestinal inflammation in iHEU may associate with stunting. However, whether the gut microbiota in iHEU causes impaired growth has not been formally tested. Beyond growth, the gut microbiota impacts immune development. Specifically, microbiota composition early in life imprint lasting immunological consequences. iHEU display high infectious morbidity including to enteric pathogens. For example, studies have shown that iHEU exhibit high prevalence of enteropathogenic Escherichia coli (EPEC) and Cryptosporidium spp compared to unexposed counterparts. The gut microbiota has been shown to protect against enteric pathogens via various mechanisms including colonization resistance and alteration of mucosal immunity. Whether gut microbiota in iHEU enhance susceptibility to enteric pathogens is unknown. Human studies are based on correlations which limit ability to infer causation. We will utilize a germ-free neonatal mouse model to investigate the causal role of the early stool microbiota in iHEU in driving these clinical phenotypes. In addition, we will use a neonatal mouse model of EPEC to test causality between stool microbiota and immunity to enteric pathogens. We hypothesize that the gut microbiota of iHEU early in life causes inflammation, poor growth and impairs immunity to enteric pathogens. We propose to test this hypothesis with the following specific aims. Aim 1: To investigate whether the early life gut microbiota of iHEU causes intestinal and systemic inflammation and impaired linear growth during infancy. Aim 2: To investigate whether the early life gut microbiota of iHEU impairs immunity to enteric pathogens