Mucosal Immunity, Vaccines and Microbiota Interplay in Humans and Animal

描述（由申请人提供）：疫苗被广泛视为具有成本效益的干预措施，用于预防和控制传统的流行病和流行病，以及限制新出现的传染病和某些生物恐怖剂的传播和影响。然而，由于缺乏关于自然感染和候选疫苗所引起的保护的“真正”（即有效的）免疫机制的信息，开发针对其中一些病原体的新疫苗和改进疫苗的工作受到阻碍。对于通过粘膜表面（包括胃肠道）进入宿主的病原体尤其如此。因此，本建议的重点是进一步了解人类Gl微环境中可能引发的保护性免疫机制。此外，由于正常的Gl菌群（微生物群）肯定会影响宿主的免疫反应，我们建议对人类局部肠道微生物群与宿主免疫反应之间的相互作用进行开创性的研究。我们将重点深入研究3种主要的革兰氏阴性细菌人类病原体，包括幽门螺杆菌、伤寒沙门氏菌和志贺氏菌，每一种主要影响胃肠道的一个不同的主要部分（分别是胃、回肠和结肠）。由于几乎所有关于保护性粘膜免疫决定因素的有限信息都来自成人研究，我们还将集中精力探索儿童和老年人对经许可的Ty21a伤寒口服免疫的反应。为了解决这项工作的复杂性，我们组建了一个多学科团队，由先天免疫和适应性免疫、分子生物学、粘膜生物学和生理学、生物化学、高通量技术、微生物学、基因组学、蛋白质化学和临床胃肠病学和疫苗学领域的知名研究人员组成（在进行内窥镜检查和开展疫苗试验方面具有丰富的经验）。此外，我们建议开发两种新技术来广泛推进人类免疫学的研究，包括基于人类的方法来研究整个伤寒沙门氏菌ORFeome以鉴定CD8+ T细胞反应，以及肽构象约束技术和潜在的粘膜佐剂来推进幽门螺杆菌疫苗。我们期望这次CCHI能够在一个对人类健康非常重要的领域提供急需的信息。

DESCRIPTION (provided by applicant): Vaccines are widely viewed as cost-effective interventions to prevent and control classical endemic and epidemic infectious diseases, as well as to limit the transmission and impact of emerging infections and certain bioterror agents. However, the development of new and improved vaccines against some of these agents is hampered by a lack of information concerning the "true" (i.e., operative) immunological mechanisms underlying the protection elicited by natural infection and by candidate vaccines. This is particularly true with regard to pathogens that enter the host via mucosal surfaces, including the gastrointestinal (Gl) tract. Thus, this proposal is focused on furthering our understanding of the protective immunological mechanisms that can be elicited in the Gl microenvironment of humans. Moreover, because the normal Gl flora (microbiota) is certain to influence the host immune response, we propose to conduct pioneering studies on the interactions between the local intestinal microbiota and the host immune response in humans. We will focus our efforts on in-depth studies of 3 major gram negative bacterial human pathogens including Helicobacter pylori, Salmonella enterica serovar Typhi and Shigella, each primarily affecting a distinct major segment of the Gl tract (i.e., the stomach, ileum and colon, respectively). Because virtually all of the limited information available concerning the determinants of protective mucosal immunity comes from studies in adults, we will also focus some efforts in exploring the responses to oral immunization with the licensed Ty21a typhoid in children and, for the first time, the elderly. To address the complexity of this undertaking, we have assembled a multidisciplinary team consisting of renowned investigators in the fields of innate and adaptive immunity, molecular biology, mucosal biology and physiology, biochemistry, high-throughput technology, microbiology, genomics, protein chemistry and clinical gastroenterology and vaccinology (with extensive experience in performing endoscopies and in conducting vaccine trials). In addition, we propose to develop two novel technologies to broadly advance the study of human immunology, including a human-based approach to study the entire S. Typhi ORFeome to identify CD8+ T cell responses and a peptide conformation constrainment technology and potential mucosal adjuvants to advance H. pylori vaccines. We expect this CCHI to yield much needed information in an area of great importance to human health. RELEVANCE: In spite of the great need for new and improved vaccines against major human pathogens, particularly those that enter the human host through the intestinal mucosa, this field is impeded by insufficient knowledge of the determinants of protective gut immunity. Moreover, little is known concerning the role of the gut microbiota in modulating the immunogenicity of oral vaccines and vice versa. The wealth of data generated by these studies is likely to lead to major advances in mucosal vaccine development in humans. PROJECT 1: PROTECTIVE IMMUNE MECHANISMS TO S. DYSENTERIAE 1 VACCINES IN CYNOMOLGUS MACAQUES AND HUMANS (Sztein, M) PROJECT 1 DESCRIPTION (provided by applicant): Shigella is a global infection that is notorious for disseminating rapidly in certain settings. One serotype, Shigella dysenteriae type 1 (S. dysenteriae 1), can cause devastating pandemics with high case fatality rates and thus it has been classified as a Category B priority pathogen with high potential to be used as a biological weapon. There is no available vaccine for Shigella. The development of effective Shigella vaccines has been hampered by a considerable lack of information of the specific determinants of protective immunity to Shigella infection. Because of the limitations imposed by the risks associated with performing challenge studies with wild type S. dysenteriae 1 in clinical trials to advance vaccine development, a nonhuman primate model is urgently needed. We have already established a challenge model with wild-type S. dysenteriae 1 strain 1617 which, to date, exhibited an attack rate of 100% (6 of 6 cynomolgus macaques challenged with 10e11 cfu intragastrically). Furthermore, we have advanced our understanding of the immune responses elicited following challenge. In this application we propose to continue these studies by addressing the following Specific Aims: (1) evaluate the hypothesis that intragastric immunization with novel attenuated S. dysenteriae 1 mutant strains elicits protection from intragastric challenge with wild type S. dysenteriae 1; (2) evaluate the hypotheses that a defined set of immune responses observed in circulation in cynomolgus immunized with attenuated strains of S. dysenteriae 1 and/or challenged with wild type S. dysenteriae 1 correlate with protection and are representative of those present at effector sites (i.e., mucosal tissues) and secondary lymphoid organs. These translational studies are central to further our understanding of the immunological mechanisms that mediate protection to S. dysenteriae 1 and longevity of the responses to vaccination in humans, (3) To evaluate the effects of immunization of monkeys with attenuated S. dysenteriae 1 strains on the colonic microbiota in stools of monkeys and the impact of the existing microbiota on the observed immune responses and protection from challenge. Finally, we will take advantage of an upcoming trial with the attenuated S. dysenteriae 1 strain CVD 1256 to evaluate the hypothesis that the immune responses observed systemically and locally in humans are similar to those that correlate with protection in cynomolgus macaques (Aims 1 and 2). These studies will provide valuable insights that might accelerate the development of attenuated vaccines for S. dysenteriae 1. RELEVANCE: The overall objective of this project is to develop a safe and effective vaccine for S. dysenteriae 1, a Category B priority pathogen with potential to be used as a biological weapon. Currently, there is no available vaccine for Shigella and limited treatment options for infections with multiple antibiotic resistant strains. Given the shortcomings of available measures to successfully control this infection, and its bioterrorism potential, to develop a S. dysenteriae type 1 vaccine is of great importance.