Adaptive immune mechanism in acute H. pylori infection

幽门螺杆菌是一种高度适应性的病原体，它逃避宿主细菌的防御(即胃酸和体液免疫)，导致慢性感染。这项建议的广泛和长期目标是阐明导致初始宿主免疫反应失败的因素，以根除幽门螺杆菌。这项研究背后的具体假设是，针对急性幽门螺杆菌感染的DC依赖的适应性免疫机制存在缺陷，导致 未能根除幽门螺杆菌。这一假设基于以下观察结果。首先，DC是最强大的抗原提呈细胞(APC)，激活后可以迁移到次级淋巴器官，启动适应性T细胞反应。其次，许多研究表明DC参与了多种疾病的发病/反应。 肠道细菌病原体。第三，APC诱导的1型T辅助细胞(Th1)反应最近被证明对疫苗诱导的幽门螺杆菌保护至关重要。 具体目标是： 1.确定幽门螺杆菌感染后DC从血液到胃的募集时程以及CCR2及其配体MCP-1在DC募集中的作用。口服幽门螺杆菌攻击的转基因CD11cp-DTR-GFP C57BL/6小鼠将通过流式细胞仪检测DC募集情况。CCR2和组织MCP-1在DC募集中的作用将通过CCR2-/-小鼠和MCP-1的中和来研究。 2.剖析了DC-H中的步骤。幽门螺杆菌在体内的相互作用和DC向次级淋巴器官的迁移。从幽门螺杆菌感染小鼠的胃相关淋巴结中分离出的DC将进行FACS分选，并通过与免疫小鼠的幽门螺杆菌特异性T细胞共培养来评估其对幽门螺杆菌的反应性。幽门螺杆菌通过DC的体内转运将通过红色荧光标记的幽门螺杆菌进行评估。 3.确定DC在幽门螺杆菌胃炎中的功能意义。白喉毒素敏感型DC转基因小鼠 将被用来评估在急性和慢性幽门螺杆菌感染期间通过给予白喉毒素而短暂的DC耗竭的影响。CCR2在急性和慢性幽门螺杆菌胃炎中的作用也将使用CCR2-/-小鼠进行研究。该项目与健康相关的是了解幽门螺杆菌诱导的慢性免疫失调的基础 胃炎，可能导致新的靶点或疫苗策略，以预防或治疗新出现的抗药性幽门螺杆菌。

Helicobacter pylori is a highly adaptive pathogen that escapes host bacterial defenses (i.e., gastric acid and humoral immunity) leading to chronic infection. The broad, long-term objective of this proposal is to elucidate the factors contributing to the failure of the initial host immune response to eradicate H. pylori. The specific hypothesis behind the proposed research is that a defective DC-dependent adaptive immune mechanism against acute H. pylori infection leads to a failure to eradicate H. pylori. This hypothesis is based on the following observations. First, DCs are the most potent antigen presenting cells (APCs) that upon activation can migrate to secondary lymphoid organs to prime an adaptive T cell response. Second, many studies have implicated the involvement of DCs in the pathogenesis/response to a variety of intestinal bacterial pathogens. Third, a type 1 T helper (Th1) response, induced by APCs, has recently been shown to be crucial for vaccine-induced protection against H. pylori. The specific aims are to: 1. Determine the time course of DC recruitment from blood to H. pylori infected stomach and the role of CCR2 and its ligand, MCP-1, in DC recruitment. Transgenic CD11cp-DTR-GFP C57BL/6 mice orally challenged with H. pylori will be assessed for DC recruitment by FACS analysis. The role of CCR2 and tissue MCP-1 in DC recruitment will be studied using CCR2-/- mice and neutralization of MCP-1. 2. Dissect the steps in the DC-H. pylori interaction in vivo and in DC migration to secondary lymphoid organs. DCs from stomach associated lymph nodes of H. pylori-infected mice will be isolated FACS sorting and their reactivity against H.pylori will be assess by coculturing DCs with H. pylori-specific T cells from immune mice. In vivo trafficking of H. pylori via DC will be assessed by red fluorochrome-labeled H. pylori. 3. Determine the functional significance of DCs in H. pylori gastritis. Transgenic mice with diphtheria toxin-sensitive DCs will be used to assess the effect of transient DC depletion during acute and chronic H. pylori infection by administrating diphtheria toxin. The role of CCR2 in acute and chronic H. pylori gastritis will also be addressed using CCR2-/- mice. The health relatedness of the project is to understand the immune dysregulation that underlies H. pylori-induced chronic gastritis which may lead to novel targets or vaccine strategies for the prevention or treatment of emerging antibioticresistant H. pylori.