Discovering the Role of Commensal Microbes on Primary B Lymphocyte Development

描述（由申请人提供）：现代免疫学的一个基本目标是了解有助于体内微生物和宿主免疫系统之间稳态平衡的因素。虽然已经做了大量的工作来了解β-内酰胺酶在形成T细胞应答中的作用，但在了解β-内酰胺酶如何影响B淋巴细胞发育和相关抗体多样化方面仍存在很大的差距。这一差距的持续存在是一个重要的问题，因为直到填补，我们对体液免疫适应性以及对过敏性和炎症性疾病的脆弱性的调节原则的理解将仍然是不完整的。本提案的总体目标是确定肠道微生物如何影响原代B细胞发育和免疫前免疫球蛋白（IG）多样化。基于申请人最近的发现，中心假设是肠道微生物通过宿主感觉仪器提供输入以调节宿主肠粘膜中的早期B细胞发育活动，从而赋予管腔抗原局部影响初级IG库的能力。这与其他几个物种（如兔和绵羊）在出生后早期利用肠道作为主要IG多样化的重要部位的观察结果一致。这项研究的基本原理是，一旦完成，该领域将垂直走向更好地理解抗体在免疫稳态中的作用，并将为进一步探索可改变的环境因素打开大门，这些因素可以作为目标，从而产生新的和创新的方法来影响与抗体产生相关的各种健康问题。利用新技术和现有技术，该提案的三个目标将建立在申请人最近的工作基础上。随着离体共培养以及建立体内标记方法的部署，目标1将测试以下概念：微生物影响肠道驻留以及骨髓支持系统以刺激早期B谱系细胞发育，并且预计将鉴定使早期B谱系细胞存活并响应微生物输入的肠道驻留支持机制。通过使用无菌和无菌设施，目标2将确定微生物组合物对形成主要IG库具有特定作用的程度。利用复杂的转基因小鼠模型和强大的成像技术，aim 3将评估肠腔抗原进入小肠固有层的程度，以及与年轻小鼠中新鲜产生的细胞结合的IG相互作用的程度。这项研究的重要性有三个原因：第一，它有望提供一个更完整的图片的一般原则，宿主：微生物相互作用的免疫调节;第二，它将是第一步，以确定在何种程度上的主要IG的剧目可以影响可变的环境暴露在生命早期;第三，它提供了一个重要组成部分，以建立一个平台，用于测试未来关于特定微生物生态对病原体、过敏原和疫苗的下游抗体反应的影响的假设。

DESCRIPTION (provided by applicant): A fundamental goal in modern immunology is to understand the factors that contribute to the homeostatic balance between commensal microbes and the host immune system. Although a great deal has been done to understand the role of commensals in shaping T cell responses, a large gap remains in understanding how commensals impact B lymphocyte development and associated antibody diversification. Continued existence of this gap is an important problem because until filled, our understanding of regulatory principles underlying humoral immune fitness as well as vulnerability to allergic and inflammatory diseases will remain incomplete. The overall objective of this proposal is to determine how commensal microbes affect primary B cell development and pre-immune immunoglobulin (Ig) diversification. Based on recent findings from the applicant, the central hypothesis is that commensal microbes provide inputs through host sensory instruments to regulate early B cell developmental activities in the host gut mucosa, thus empowering luminal antigens with the capacity to influence the primary Ig repertoire locally. This is consistent with observations that several other species, such as rabbits and sheep, utilize the intestine as a significant site for primary Ig diversification early in post-natal life. The rationale for the proosed research is that, once accomplished, the field will move vertically towards a greater understanding of the role of commensals in immune homeostasis and will open the door to further exploration of modifiable environmental factors that could be targeted, resulting in new and innovative approaches to influence a variety of health issues relevant to antibody production. Using both new as well as established technologies, this proposal's three aims will build upon the applicant's recent work. With the deployment of ex vivo co-culture as well as established in vivo labeling methods, aim 1 will test the notion that commensals influence both gut-resident as well as bone marrow support systems to stimulate early B lineage cell development and is expected to identify the gut-resident support mechanisms enabling early B lineage cells to survive and respond to microbial input. With the use of germ-free and gnotobiotic facilities, aim 2 will determine the extent to which microbe composition has specific effects to shape the primary Ig repertoire. With sophisticated genetically modified mouse models as well as powerful imaging technologies, aim 3 will evaluate the degree to which luminal antigens gain access to the intestinal lamina propria and interact with freshly-produced, cell-bound Ig in young mice. The proposed research is significant for the following three reasons - first, it promises to provide a more complete picture of the general principles of host:microbe interactions in immune regulation; second, it will be a first step to identify the extent to which primary Ig repertoires can be influenced by modifiable environmental exposures early in life; and third, it provides an essential component to establish a platform for testing future hypotheses regarding the effect of specific commensal microbe ecologies on downstream antibody responses to pathogens, allergens and vaccines.