Investigating cross-regulation of the microbiome and mucosal immune system using humanized mice

 描述(申请人提供)：在肠道中，在生命早期接触共生微生物是粘膜免疫耐受和动态平衡发展的关键决定因素。耐受性和稳态免疫通路的功能障碍是各种慢性炎症性疾病的基础，不仅包括克罗恩病和溃疡性结肠炎，还包括过敏，甚至结直肠癌。与这些疾病相关的免疫功能障碍是复杂的，仍然不完全清楚，进一步确定这些机制具有重要的临床意义。近年来，微生物群在人类健康和疾病中的作用已成为人们密切关注的领域。尽管人类微生物组的序列分析已经表征了健康和疾病中粘膜界面上存在的微生物群落，但我们对人类肠道微生物组和人类粘膜免疫系统之间的关系的了解仍然不完整。全基因组关联研究已经确定了许多与炎症性肠病(IBD)风险改变相关的多态性，其中许多与宿主防御有关，并可能导致生物失调，这是IBD的一个公认的标志。目前尚不清楚是否会导致生物失调。 由这些变异或是潜在炎症的结果。同样，目前尚不清楚IBD患者微生物组的变化是否足以促进免疫失调。实验小鼠模型提供了一些洞察力，但小鼠炎症模型中的疾病征兆往往与人类疾病的相关性很差。此外，已有研究表明，小鼠粘膜免疫系统的发展和成熟需要宿主特有的肠道微生物群，这就需要新的实验系统来研究人类的免疫生物学。我的目标是了解人类黏膜免疫系统和人类微生物群之间的交叉调节。我已经开发了一种新的人源化小鼠品系，当使用带有突变的FOXP3的HSCs时，它可以显示适应性免疫反应，并可以重现人类免疫疾病。我已经将该菌株重新衍生为无菌条件，以允许确定的定植策略来研究人类黏膜免疫发育/功能和人类肠道微生物组的动态，提供了一个机会来表征正在发育的人类黏膜免疫系统，这是以前在实验模型中没有实现的。我的假设是，遗传易感性和生物多样性都会改变粘膜免疫发育，并导致肠道内异常的免疫反应，我将从三个方面来解决这个问题：1)生物多样性是否影响人类黏膜免疫系统；2)遗传易感性是否扰乱微生物群的稳定性；3)外源性给予微生物副产物或代谢物是否增强人类Treg的发育。

 DESCRIPTION (provided by applicant): In the intestine, exposure to commensal microbes early in life is a key determinant in the development of mucosal immune tolerance and homeostasis. Dysfunction of tolerogenic and homeostatic immune pathways underlies a broad variety of chronic inflammatory disorders, including not just Crohn's disease and ulcerative colitis, but also allergy, and even colorectal cancer. The immune dysfunction associated with such disorders is complex and still incompletely understood, and further defining these mechanisms is of significant clinical relevance. In recent years the role of the microbiome in human health and disease has become an area of intense focus. Although sequence profiling of the human microbiome has characterized the microbial communities present at mucosal interfaces in health and disease, our understanding of the relationship between the human intestinal microbiome and human mucosal immune system remains incomplete. Genome-wide association studies have identified numerous polymorphisms that are associated with altered risk for inflammatory bowel disease (IBD), many of which are involved in host defense and may contribute to dysbiosis, a well-established hallmark of IBD. It is not known if dysbiosis is caused by these variants or is a result from underlying inflammation. Similarly, it is unknown whether alterations in the microbiome of IBD patients are sufficient to promote immune dysregulation. Experimental murine models have given some insight but disease signatures in murine models of inflammation often poorly correlate with human disease. Furthermore, it has been shown that development and maturation of the murine mucosal immune system requires host-specific gut microbiome necessitating novel experimental systems to investigate human immunobiology. My goal is to understand the cross-regulation between the human mucosal immune system and human microbiome. I have developed a novel humanized mouse strain that displays adaptive immune responses and can recapitulates a human immune disease when using HSCs with mutated FOXP3. I have re-derived this strain into germ-free conditions to permit defined colonization strategies to investigate human mucosal immune development/function and the dynamics of the human intestinal microbiome providing an opportunity to characterize the developing human mucosal immune system not previously achieved in experimental models. My hypothesis is that both genetic susceptibility and dysbiosis alter mucosal immune development and contributes to aberrant immune responses in the intestine and I will address this in three aims: 1) whether dysbiosis impacts human mucosal immune system 2) whether genetic susceptibility perturbs microbiome stability; 3) whether exogenous administration of microbial byproducts or metabolites potentiates human Treg development.