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

描述(申请人提供)：彩虹鲑鱼(我们的鱼类模型)，已知含有至少三种免疫球蛋白同种类型，IgM，IGD和最近发现的IGT。到目前为止，关于IGT的蛋白质结构和分布及其在免疫中的具体作用尚不清楚。我们已经产生了针对IGT的抗体，这导致我们发现了一种仅表达表面IGT的新的B细胞亚群。值得注意的是，IGT+B细胞是鲑鱼肠道中最常见的B细胞类型。用肠道寄生虫沙斯塔弧菌感染鲑鱼，发现存活鱼的肠道上皮和固有层中有大量IGT+B细胞的浸润。最值得注意的是，我们发现针对寄生虫的IGT特异性滴度仅限于肠道粘液，而IgM是参与血清反应的唯一同型。进一步支持IGT在肠道动态平衡中的作用，我们发现大多数肠道细菌都被IGT包裹。总而言之，这些数据表明，IGT在功能上等同于哺乳动物的IgA。这项建议的首要目标是使用我们的鱼-寄生虫模型来获得对粘膜免疫的原始见解，这将有助于分析现有的人类粘膜免疫学范式。到目前为止，用于研究肠道粘膜免疫的动物模型仅限于哺乳动物。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。由于鱼的肠道中没有Peyer斑块和淋巴结，局部粘膜反应的空间和功能复杂性应该较低，从而有助于分析滤泡外IGT，进而分析IgA反应。因此，这项建议中产生的数据可能会阐明肠道IGT/IgA介导的免疫的新机制，这些机制独立于滤泡结构的存在。寻找卵泡外产生IGT/IgA的途径将是开发新的粘膜疫苗策略的基础。因此，这项提案的目标是：目标1：鲑鱼肠道中IGT的生化特性、生产和运输。在这里，我们将完成肠道IGT和IGT分泌细胞的特征，并将通过新发现的彩虹鲑鱼Ig聚合受体(TIgPr)来研究IGT进入肠腔区域的机制。目的：研究沙棘对小鼠肠道IGT免疫反应的机制和途径。在这里，我们将研究卵泡外IGT和IGT+B细胞对Cerom yxa Shasta的反应机制和途径。为此，我们将对感染寄生虫的鱼的IGT反应进行时空分析，并调查IGT+B细胞归巢到受感染鱼的肠道的途径。目的3.探讨肠道IGT和IGT+B细胞对沙门氏菌的初级效应作用。这一目标的主要目的是确定寄生虫诱导的IGT特异性反应是否具有保护性，并阐明IGT和IGT+B细胞在保护鱼类免受寄生虫入侵方面的作用机制。。 公共卫生相关性：我们已经证明IGT是一种新发现的硬骨免疫球蛋白，是哺乳动物IgA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鲑鱼的肠道中诱导强烈的IGT特异性反应。因此，这项建议的首要目标是使用我们的鱼-寄生虫模型来获得对粘膜免疫的原始见解，这将有助于分析现有的人类粘膜免疫学范式。到目前为止，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。应当强调，塑造鱼类和哺乳动物粘膜免疫系统的选择性力量(即宿主-微生物致病或相互作用)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学解决方案可能具有基本的结构和机制方面的共同点。事实上，哺乳动物肠道中的免疫球蛋白A被认为是“调节肠道微生物群落的原始形式的适应性免疫”。事实上，哺乳动物的粘膜免疫功能可能一直保持着“原始”的特征，这恰恰是因为鱼类和哺乳动物的粘膜表面的选择性力量和物理约束基本上非常相似。由于鱼的肠道中没有Peyer斑块和淋巴结，局部粘膜反应的空间和功能复杂性应该较低，从而有助于分析滤泡外IGT，进而分析IgA反应。因此，这项建议中产生的数据可能会阐明肠道IGT/IgA介导的免疫的新机制，这些机制独立于滤泡结构的存在。寻找卵泡外产生IGT/IgA的途径将是开发新的粘膜疫苗策略的基础。此外，这一知识将有助于治疗由于粘膜免疫反应失调而发展起来的疾病(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在短期和长期内为鱼类养殖业做出贡献，从而造福社会。养鱼业的主要问题包括与健康和疾病问题有关的问题。因此，更好地了解鱼类免疫系统对于开发新的治疗剂和疫苗以预防鱼类疾病至关重要。

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.