Molecular Mechanisms of Campylobacter Jejuni-induced Pathogenesis

描述(由申请人提供)：革兰氏阴性侵袭性细菌空肠弯曲杆菌(C.jejui)是全球细菌性食源性胃肠道疾病的主要原因，仅在美国每年就有大约200-300万例病例。此外，空肠弯曲菌感染与感染后并发症有关，如关节炎和神经退行性疾病Guillian-Barri综合征。因此，空肠弯曲菌感染有可能导致急性/慢性肠道疾病和衰弱的肠外疾病。虽然空肠弯曲菌感染是一个严重的健康问题，但关于宿主反应和这种微生物引发疾病的分子机制的信息有限。缺乏模拟空肠弯曲菌诱导的发病机制的小鼠模型可能是造成这种认识差距的原因之一。在初步研究中，我们观察到诺知生菌空肠弯曲菌相关的IL-10/-；NF？BEGFP小鼠出现严重的血性腹泻和肠道炎症，与NF？B的激活有关。在这个方案中，我们假设来自肠上皮细胞和髓系细胞的核因子？B信号有助于宿主对空肠弯曲菌感染的反应，并有助于重建肠道内环境的稳定。因此，核因子B信号在时间和空间(细胞)上的不当激活将对宿主产生病理后果，导致微生物无法清除，从而导致炎症的发生。我们将通过两个特定的目的来验证我们的假设：1)剖析核因子B信号在空肠弯曲菌介导的致病机制中的细胞作用。2)确定RelA依赖基因对空肠弯曲菌易位和细胞内存活的影响。该项目将利用体内和体外两种方法来确定肠细胞和髓系来源的核因子？B信号在宿主对空肠弯曲菌反应中的作用和功能。我们的目标是选择性地删除IL-10-/-小鼠肠细胞和髓系细胞中的RelA(核因子？B亚单位)，以探讨核因子？B信号在宿主对空肠弯曲菌应答中的作用。本研究的最终目的是在分子水平上了解宿主对空肠弯曲菌感染的反应，并确定各种信号事件在发病机制中的功能参与。这种知识的获得可以用来调节这种病原微生物对宿主的有害影响，并帮助设计有效的预防措施。未来的目标包括表征导致这种细菌致病的空肠弯曲菌毒力因子。 与公共卫生相关：空肠弯曲杆菌感染已成为全球细菌性食源性腹泻疾病的主要原因，仅在美国每年就有多达240万例。尽管存在这种健康和社会经济负担，但科学界和医学界对宿主对这种致病微生物的反应知之甚少。这一知识差距对控制空肠弯曲菌介导性疾病的新治疗替代方案的设计产生了负面影响。本项目通过基因去除易感小鼠株IL-10-/-中的核因子？B转录亚单位relA(P65)来研究空肠弯曲菌诱导致病的分子机制。该项目将阐明肠细胞和髓系来源的核因子？B信号在宿主对空肠弯曲菌感染的反应中的作用。这一新的认识将大大有助于理解空肠弯曲菌的发病机制，并可能导致新的治疗策略的设计。

DESCRIPTION (provided by applicant): The Gram-negative invasive bacterium Campylobacter jejuni (C. jejuni) is the leading cause of bacterial food-borne gastrointestinal illness worldwide, with approximately 2-3 million annual cases in the United States alone. In addition, C. jejuni infection is associated with post-infectious complications such as arthritis and the neurodegenerative disorder Guillian-Barri syndrome. Therefore, C. jejuni infection has the potential to cause both acute/chronic intestinal disorders and debilitating extra-intestinal illnesses. Although C. jejuni infection represents a serious health concern, limited information is available on both host responses and the molecular mechanisms by which the microorganism triggers diseases. The lack of a murine model mimicking C. jejuni induced pathogenesis likely contributed to this gap of knowledge. In preliminary studies, we observed that gnotobiotic C. jejuni-associated IL-10-/-; NF?BEGFP mice developed severe bloody diarrhea and intestinal inflammation associated with NF?B activation. In this proposal, we hypothesize that NF?B signaling derived from intestinal epithelial cells and myeloid cells contributes to the host response to C. jejuni infection and to the reestablishment of intestinal homeostasis. Consequently, improper temporal and spatial (cellular) activation of NF?B signaling will have pathological consequences for the host, leading to failure to clear the microorganism and development of inflammation. We will test our hypothesis with two SPECIFIC AIMS: 1) Dissect the cellular contribution of NF?B signaling in C. jejuni mediated pathogenesis. 2) Determine the impact of RelA-dependent genes on C. jejuni translocation and intracellular survival. This project will utilize both in vivo and in vitro approaches to define the role and function of enterocyte and myeloid-derived NF?B signaling in the host response to C.jejuni. Our goal is to selectively delete RelA (NF?B subunit) in enterocytes and myeloid cells of IL-10-/- mice to address the function of NF?B signaling in the host response to C. jejuni. The ultimate goal of this proposal is to understand, at the molecular level, host responses to C. jejuni infection and to determine the functional involvement of various signaling events in the development of the pathogenesis. This gain of knowledge could be utilized to modulate the deleterious impact of this pathogenic microorganism on the host and help design effective preventive measures. Future goals include the characterization of C. jejuni virulence factors responsible for the pathogenesis of the bacterium. PUBLIC HEALTH RELEVANCE: Campylobacter jejuni (C.jejuni) infection has become the predominant cause of bacterial-food borne diarrheal diseases worldwide with up to 2.4 million cases annually in the United States alone. Despite this health and socio-economical burden, the scientific and medical community knows little about the host response to this pathogenic microorganism. This gap of knowledge negatively impact on the design of new therapeutic alternative to control for C.jejuni mediated illnesses. This project investigates the molecular mechanism of C. jejuni-induced pathogenesis through genetic removal of the NF?B transcriptional subunit RelA (p65) in the susceptible murine strain IL-10-/-. The project will elucidate the function of enterocyte- and myeloid-derived NF?B signaling in host responses to C. jejuni infection. This new knowledge would significantly contribute to the understanding of C. jejuni pathogenesis and could lead to the design of new therapeutic strategies.