Adaptive immune mechanism in acute H. pylori infection

急性幽门螺杆菌感染的适应性免疫机制

• 批准号: 6969099
• 负责人: JOHN Y KAO
• 金额: $ 13.21万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-15 至 2010-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6969099
• 关键词: Helicobacter; antigen presentation; antigen presenting cell; bacteria infection mechanism; cell migration; chemokine receptor; dendritic cells; diphtheria toxin; flow cytometry; gastrointestinal infection; genetically modified animals; helper T lymphocyte; host organism interaction; immunopathology; laboratory mouse; monocyte chemoattractant protein 1; pathologic process; stomach

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.

幽门螺杆菌是一种高度适应性的病原体，可以逃避宿主细菌防御（即胃酸和体液免疫），导致慢性感染。该提案的广泛、长期目标是阐明导致最初宿主免疫反应未能根除幽门螺杆菌的因素。这项研究背后的具体假设是，针对急性幽门螺杆菌感染的有缺陷的 DC 依赖性适应性免疫机制导致 未能根除幽门螺杆菌。该假设基于以下观察。首先，DC 是最有效的抗原呈递细胞 (APC)，激活后可以迁移到次级淋巴器官以引发适应性 T 细胞反应。其次，许多研究表明 DC 参与多种疾病的发病机制/反应。 肠道细菌病原体。第三，APC 诱导的 1 型 T 辅助细胞 (Th1) 反应最近已被证明对于疫苗诱导的幽门螺杆菌保护至关重要。 具体目标是： 1.确定DC从血液募集到幽门螺杆菌感染的胃的时间过程以及CCR2及其配体MCP-1在DC募集中的作用。将通过FACS分析评估经口幽门螺杆菌攻击的转基因CD11cp-DTR-GFP C57BL/6小鼠的DC募集情况。将使用 CCR2-/- 小鼠和 MCP-1 的中和来研究 CCR2 和组织 MCP-1 在 DC 募集中的作用。 2. 剖析 DC-H 中的步骤。幽门螺杆菌在体内和 DC 迁移到次级淋巴器官中的相互作用。来自幽门螺杆菌感染小鼠的胃相关淋巴结的DC将被分离FACS分选，并且将通过将DC与来自免疫小鼠的幽门螺杆菌特异性T细胞共培养来评估它们针对幽门螺杆菌的反应性。幽门螺杆菌通过 DC 的体内运输将通过红色荧光染料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。具有白喉毒素敏感 DC 的转基因小鼠 将用于评估在急性和慢性幽门螺杆菌感染期间通过施用白喉毒素来短暂去除 DC 的效果。还将使用 CCR2-/- 小鼠来探讨 CCR2 在急性和慢性幽门螺杆菌胃炎中的作用。该项目的健康相关性是了解幽门螺杆菌引起的慢性疾病背后的免疫失调 胃炎，这可能会导致新的目标或疫苗策略来预防或治疗新出现的抗生素耐药性幽门螺杆菌。