Specific Contribution of a New IG Isotype (IGT) in Teleost Fish Immune Responses

描述（由申请人提供）：虹鳟鱼（我们的鱼类模型）已知含有至少三种免疫球蛋白同种型，IgM、IgD和最近发现的IgT。迄今为止，对IgT的蛋白质结构和分布及其在免疫中的具体作用还不清楚。我们已经产生了针对IgT的抗体，这使我们发现了一种新的B细胞亚群，其仅表达表面IgT。值得注意的是，IgT+ B细胞代表鳟鱼肠道中最普遍的B细胞类型。用C. Shasta，一种肠道寄生虫，揭示了IgT+ B细胞在存活鱼的肠道上皮和固有层中的大量浸润。最值得注意的是，我们发现针对寄生虫的特异性IgT滴度仅限于肠道粘液，而IgM是参与血清反应的唯一同种型。进一步支持IgT在肠道内稳态中的作用，我们发现大多数肠道细菌被IgT包被。总的来说，这些数据表明IgT代表哺乳动物伊加的功能等同物。这项建议的首要目标是使用我们的鱼寄生虫模型，以获得原始的粘膜免疫的见解，这将有利于现有的范式在人类粘膜免疫学的分析。迄今为止，用于研究肠道粘膜免疫的动物模型仅限于哺乳动物物种。因此，我们对鱼类的研究将为该领域提供一个新的系统发育维度。由于鱼缺乏派伊尔补丁和淋巴结的肠道，一个较低的空间和功能的复杂性，局部粘膜反应应预期，从而促进滤泡外IgT的分析，并通过扩展，伊加，反应。因此，在这个建议中产生的数据可能阐明新的机制，肠IgT/IgA介导的免疫是独立的滤泡结构的存在。找到IgT/伊加产生的滤泡外途径将是开发新的粘膜疫苗接种策略的基础。因此，该提案的目标是：目的1：鳟鱼肠道中IgT的生物化学表征、生产和运输。在这里，我们将完成肠道IgT和IgT分泌细胞的特性，我们将调查的机制，参与运输的IgT到肠道管腔面积，通过一个新发现的虹鳟鱼IG聚合物受体（TIgPr）。目的2：探讨角潜蝇肠道IgT免疫应答的机制和途径.在这里，我们将探讨滤泡外的机制和途径，IgT和IgT+ B细胞响应Ceratomyxa shasta。为此，我们将进行一个时间-空间分析的IgT反应感染寄生虫的鱼，我们将调查途径IgT+ B细胞归巢到肠道感染的鱼。AIM 3.目的探讨肠道IgT和IgT+B细胞对C.沙斯塔。该目的的主要目标是确定由寄生虫诱导的产生的IgT特异性反应是否具有保护性，并阐明IgT和IgT+ B细胞有助于保护鱼类免受寄生虫入侵的效应器机制。. 公共卫生相关性：我们已经证明，IgT，一种新发现的硬骨鱼免疫球蛋白，是哺乳动物伊加的功能同系物。我们已经建立了一个模型系统，使用肠道寄生虫在虹鳟鱼肠道中诱导强烈的IgT特异性反应。因此，这项建议的首要目标是使用我们的鱼寄生虫模型，以获得粘膜免疫的原始见解，这将有助于分析现有的范式在人类粘膜免疫学。迄今为止，用于研究粘膜免疫的动物模型仅限于哺乳动物物种。因此，我们对鱼类的研究将为该领域提供一个新的系统发育维度。应该强调的是，塑造鱼类和哺乳动物粘膜免疫系统的选择力（即宿主-微生物致病或互利相互作用）是相似的。因此，在鱼类和哺乳动物中由这些选择性力量驱动的一些新的免疫解决方案可能具有基本的结构和机制方面。事实上，哺乳动物肠道伊加被认为是“调节肠道微生物群落的适应性免疫的原始形式”。事实上，哺乳动物的粘膜免疫功能可能仍然是“原始的”，正是因为鱼类和哺乳动物的粘膜表面的选择力和物理约束基本上非常相似。由于鱼缺乏派伊尔补丁和淋巴结的肠道，一个较低的空间和功能的复杂性，局部粘膜反应应预期，从而促进滤泡外IgT的分析，并通过扩展，伊加，反应。因此，在这个建议中产生的数据可能阐明新的机制，肠IgT/IgA介导的免疫是独立的滤泡结构的存在。找到IgT/伊加产生的滤泡外途径将是开发新的粘膜疫苗接种策略的基础。此外，这些知识将有助于帮助治疗由于粘膜免疫应答失调而发展的疾病（即，炎症性肠病、克罗恩病）。值得注意的是，鱼类饮食的有益效果是众所周知的（即，低脂肪、低胆固醇）。因此，鱼类饲料的消费量正在以非常快的速度增长。我们对鱼类免疫系统的研究也将通过在短期和长期对养鱼业做出贡献而造福社会。鱼类养殖的主要问题之一是与健康和疾病有关的问题。因此，更好地了解鱼类免疫系统对于开发预防鱼类疾病的新治疗剂和疫苗至关重要。

DESCRIPTION (provided by applicant): Rainbow trout (our fish model), is known to contain at least three immunoglobulin isotypes, IgM, IgD and the recently discovered IgT. Thus far nothing is known about the protein structure and distribution of IgT, and its specific role in immunity. We have generated antibodies against IgT that has led us to the finding of a novel B cell subset expressing exclusively surface IgT. Significantly, IgT+ B cells represent the most prevalent B cell type in the gut of trout. Infection of trout with C. shasta, a gut parasite, revealed a massive infiltration of IgT+ B cells in the gut epithelium and lamina propria of survivor fish. Most notably, we found that IgT-specific titers against the parasite were confined to gut mucus, whereas IgM was the only isotype involved in serum responses. Supporting further the role of IgT in gut homeostasis, we found that a majority of intestinal bacteria were coated with IgT. Collectively, these data indicate that IgT represents the functional equivalent of mammalian IgA. The overarching goal of this proposal is to use our fish-parasite model to gain primordial insights of mucosal immunity that will facilitate the analysis of existing paradigms in human mucosal immunology. To date, the animal models being used to study gut mucosal immunity are limited to mammalian species. Thus, our studies with fish will provide a new phylogenetic dimension into the field. Since fish lack peyer patches and lymph nodes in the gut, a lower spatial and functional complexity of the local mucosal responses should be expected, thereby facilitating the analysis of extrafollicular IgT, and by extension, IgA, responses. Accordingly, data generated in this proposal is likely to elucidate novel mechanisms of intestinal IgT/IgA-mediated immunity that are independent of the presence of follicular structures. Finding extrafollicular pathways of IgT/IgA production will be fundamental to developing novel mucosal vaccination strategies. Thus, the goals of this proposal are: AIM 1: Biochemical characterization, production and transport of IgT in the gut of trout. Here we will complete the characterization of gut IgT and IgT-secreting cells, and we will investigate the mechanisms involved in the transport of IgT into the gut luminal area, through a newly discovered rainbow trout Ig polymeric receptor (TIgPr). AIM 2: Mechanisms and pathways involved in the development of gut IgT immune responses to Ceratomyxa shasta. Here we will investigate the extrafollicular mechanisms and pathways by which IgT and IgT+ B cells respond to Ceratomyxa shasta. To this end, we will perform a temporal-spatial analysis of the IgT response in fish infected with the parasite, and we will investigate pathways of IgT+ B cell homing into the gut of infected fish. AIM 3. To investigate the primary effector functions of gut IgT and IgT+B cells against C. shasta. The main goals of this aim are to establish whether the generated IgT-specific responses induced by the parasite are protective, and to elucidate the effector mechanisms by which IgT and IgT+ B cells contribute to protecting fish from parasite invasion. . PUBLIC HEALTH RELEVANCE: We have demonstrated that IgT, a newly discovered teleost immunoglobulin, is the functional homolog of mammalian IgA. We have established a model system that uses a gut parasite to induce strong IgT-specific responses in the gut of rainbow trout. Thus, the overarching goal of this proposal is to use our fish-parasite model to gain primordial insights of mucosal immunity immunity that will facilitate the analysis of existing paradigms in human mucosal immunology. To date, the animal models being used to study mucosal immunity are limited to mammalian species. Thus, our studies with fish will provide a novel phylogenetic dimension into the field. It should be stressed that the selective forces (i.e. host-microbial pathogenic or mutualistic interactions) that have shaped fish and mammalian mucosal immune systems are similar. Thus, some of the novel immunological solutions driven by these selective forces in fish and mammals are likely to share fundamental structural and mechanistic aspects. In fact, the mammalian intestinal IgA is considered a "primitive form of adaptive immunity that regulates microbial communities in the gut". Indeed, the features of mucosal immunity in mammals may have remained "primitive" precisely because the selective forces and physical constraints of mucosal surfaces of fish and mammals are basically very similar. Since fish lack peyer patches and lymph nodes in the gut, a lower spatial and functional complexity of the local mucosal responses should be expected, thereby facilitating the analysis of extrafollicular IgT, and by extension, IgA, responses. Accordingly, data generated in this proposal is likely to elucidate novel mechanisms of intestinal IgT/IgA-mediated immunity that are independent of the presence of follicular structures. Finding extrafollicular pathways of IgT/IgA production will be fundamental to developing novel mucosal vaccination strategies. In addition, this knowledge will be instrumental to help treating diseases that develop as result of the dysregulation of mucosal immune responses (i.e., inflammatory bowel disease, Crohn's disease). It is worth noting that the beneficial effects of fish diets are well-known (i.e., low fat, low cholesterol). Thus, the consumed of fish diets is growing at a very fast pace. Our studies on the fish immune system will also benefit society by contributing to the fish farming industry in the short and long-term. Among the major problems in fish farming are those related to health and disease issues. Therefore, a better knowledge of the fish immune system is essential to the development of new therapeutic agents and vaccines to prevent fish diseases.