CHARACTERIZATION OF THE ROLE OF THE SMALL INTESTINAL MICROBIOTA IN THE PATHOGENESIS OF ENVIRONMENTAL ENTERIC DYSFUNCTION IN UNDERNOURISHED CHILDREN AND MOTHERS

摘要 在世界范围内，五分之一的五岁以下儿童表现为营养不良，表现为线性生长受损，或 发育迟缓。发育迟缓，被定义为具有年龄长度z分数(LAZ；-2)，与发育不良有关 结果，包括神经发育和免疫反应受损。此外，发育迟缓及其长期- 长期的后遗症代代相传，导致了营养不良的代际循环。现有 营养干预未能显著改善发育迟缓，突显了(I)更好地了解其他 造成发育迟缓的因素和(2)将临床工作重点放在治疗产妇营养不良上，以便 打破代际营养不良的循环。近年来，一种名为环境的亚临床疾病 肠功能障碍(EED)被认为是全球45%的儿童发育迟缓的原因。EED是一种 局限于小肠的炎症性肠病；其组织学特征是绒毛丢失和 吸收表面积、上皮屏障功能障碍和椎板中的免疫炎症浸润物 专有的。虽然对EED的发病机制知之甚少，但研究人员推测肠道疾病在其中起了一定的作用。 微生物。然而，在很大程度上，对小肠微生物区系的研究仍然不足，部分原因是挑战 来获取样本。此外，几乎没有EED的实验模型，这些模型都不能解释 营养不良的代际性质。 我推测，肠道微生物区系的紊乱在发病机制中起了因果作用。 因此，几代人都存在营养不良的问题。为了检验这一假设，第一个 这项建议的目的将使用诺生菌小鼠来表征肠病和生长的传播性。 孟加拉儿童和妇女的小肠微生物群摇摇欲坠，有EED的证据基于 他们的十二指肠活检的组织病理学。从十二指肠培养的测序细菌菌株集合 从这些发育迟缓的儿童和营养不良的妇女那里获得的吸入物(BMI&lt；18.5公斤/平方米)将被引入 变成年轻的无菌小鼠。我将通过执行免疫细胞图谱，蛋白质来表征宿主的病理 免疫分析和转录图谱(全组织和单细胞)。微生物群落结构将是 通过对群落DNA的鸟枪测序进行量化，并通过微生物RNA表达群落功能 序列号。同时，我将通过引入这些微生物L来建立一个新的代际营养不良模型 社区变成无菌水坝，并评估水坝及其幼崽的病理学。第二个目标是测试 十二指肠导入预防和/或治疗诺生菌小鼠模型的肠病 细菌群落来自健康的孟加拉国妇女(体重指数正常)。预防或改善 来自健康女性的十二指肠细菌群落的肠道疾病将有助于进一步鉴定分类群 这可能会促进或减少病理学。这些实验将为临床前测试小鼠的作用提供依据 肠道微生物区系在EED的发病机制中的作用，并可能导致EED治疗靶点的确定。

ABSTRACT Worldwide, one in five children under five years of age manifests undernutrition as impaired linear growth, or stunting. Stunting, defined as having a length-for-age z-score (LAZ) < -2, is associated with poor developmental outcomes, including impaired neurodevelopment and immune responses. Furthermore, stunting and its long- term sequelae persist across generations, contributing to an intergenerational cycle of undernutrition. Existing nutritional interventions fail to substantially improve stunting, highlighting the need to (i) better understand other factors contributing to stunting and (ii) focus clinical efforts towards treating maternal undernutrition in order to break the cycle of intergenerational undernutrition. In recent years, a subclinical disorder called environmental enteric dysfunction (EED) has been suggested to contribute to 45% of childhood stunting globally. EED is an inflammatory enteropathy localized to the small intestine; it is characterized histologically by loss of villi and absorptive surface area, epithelial barrier dysfunction, and an immunoinflammatory infiltrate in the lamina propria. While the pathogenesis of EED is poorly understood, researchers have postulated a role for enteric microorganisms. However, the small intestinal microbiota remains largely understudied, in part due to challenges in gaining access to samples. Moreover, few experimental models of EED exist, none of which account for the intergenerational nature of undernutrition. I hypothesize that perturbations in the small intestinal microbiota play a causal role in the pathogenesis of EED and consequently undernutrition that persists across generations. To test this hypothesis, the first aim of this proposal will use gnotobiotic mice to characterize the transmissibility of enteropathy and growth faltering by the small intestinal microbiota of Bangladeshi children and women with evidence of EED based on histopathology of their duodenal biopsies. Collections of sequenced bacterial strains, cultured from duodenal aspirates obtained from these stunted children and malnourished women (BMI<18.5 kg/m2) will be introduced into young germ-free mice. I will characterize host pathology by performing immune cell profiling, protein immunoassays, and transcriptional profiling (whole tissue and single cell). Microbial community structure will be quantified by shotgun sequencing of community DNA, and expressed community functions by microbial RNA- Seq. In parallel, I will establish a novel model of intergenerational undernutrition by introducing these microbia l communities into germ-free dams and assessing the pathology in dams and their pups. The second aim will test prevention and/or treatment of enteropathy in the gnotobiotic mouse models through introduction of duodenal bacterial communities derived from healthy Bangladeshi women (with normal BMI). Prevention or amelioration of enteropathy by duodenal bacterial communities from healthy women will allow further identification of taxa that may promote or reduce pathology. These experiments will provide a pre-clinical test of the role of the small intestinal microbiota in the pathogenesis of EED and could result in identification of therapeutic targets for EED.