Mechanisms of Salmonella Invasion and Transmigration

沙门氏菌入侵和迁移的机制

• 批准号: 8529502
• 负责人: James E. Casanova
• 金额: $ 30.3万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-03-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8529502
• 关键词: Actins; Animals; Antibiotic Resistance; Antibiotics; Apoptosis; Apoptotic; Bacteria; Bacterial Antigens; Bacterial Attachment Site; Biochemical; C-terminal; Cell Adhesion; Cell membrane; Cells; Cessation of life; Cytoplasm; Cytoskeleton; Dendritic Cells; Development; Epithelial; Epithelial Cells; Epithelium; Equilibrium; Exhibits; Exposure to; Failure; Focal Adhesion Kinase 1; Funding; Gastritis; Gastroenteritis; Goals; Growth; Immigration; Immune; Immune response; Immune system; Impairment; In Vitro; Infection; Infiltration; Inflammatory; Intercept; Intestines; Invaded; Knock-out; Knockout Mice; Mediating; Membrane; Mesentery; Microfilaments; Molecular; Muramidase; Mus; Myeloid Cells; Neutrophil Infiltration; Oral; Pathogenesis; Penetration; Phagocytes; Phagocytosis; Phagosomes; Phase; Population; Prevention therapy; Process; Production; Protein Tyrosine Kinase; Proteins; RNA Interference; Receptor Signaling; Regulation; Reporting; Research; Resistance; Role; Salmonella; Salmonella infections; Salmonella typhimurium; Signal Transduction; Site; Structure of aggregated lymphoid follicle of small intestine; Symptoms; Syringes; Systemic disease; T-Lymphocyte; Testing; Tissues; Toll-like receptors; Typhoid Fever; Yeasts; base; combat; cytokine; human disease; in vivo; insight; intestinal epithelium; killings; lymph nodes; macrophage; migration; monocyte; neutrophil; next generation; novel; oral infection; pathogen; protein function; public health relevance; resistant strain; response; success; yeast two hybrid system

DESCRIPTION (provided by applicant): Salmonella infect their animal hosts by entering into and traversing the intestinal epithelial barrier. Penetration of the epithelium is primarily achieved by direct invasion of host epithelial cells using a panel of effector molecules secreted through a Type III secretion apparatus. SipC, which forms part of the tip of this apparatus, has long cytoplasmic N- and C-termini, which nucleate the assembly of actin filament networks that are required for bacterial engulfment. Using a yeast two-hybrid screen, we identified a number of host proteins that interact selectively with the C-terminus of SipC. These include proteins that regulate actin assembly and dynamics, as well as proteins that mediate vesicular transport. We hypothesize that Salmonella uses SipC to nucleate the assembly of signaling and cytoskeletal machinery at sites of bacterial attachment to coordinate actin remodeling with the delivery of new membrane to form the nascent phagosome. This hypothesis will be explored in Specific Aim 1. Salmonella infection triggers the recruitment of inflammatory monocytes to the intestine, which have an important role in clearance of the infection. However, Salmonella can also use phagocytes as vehicles for their systemic dissemination, and the success or failure of the host response lies in the balance between these two processes. We are examining the role of Focal Adhesion Kinase (FAK) in the migration and function of monocytic cells. Using mice that conditionally lack FAK in cells of the myeloid lineage, we found that infiltration of inflammatory macrophages into the Peyer's patches and mesenteric lymph nodes is impaired in the absence of FAK, and that this surprisingly correlates with reduced bacterial colonization of all tissues examined. Conversely, neutrophil infiltration into the same tissues is enhanced, suggesting a differential regulation of macrophage and neutrophil recruitment to infected tissues. We hypothesize that inflammatory macrophages are necessary for bacterial survival in the tissue microenvironment, by providing a protective niche for bacterial replication and dissemination, and that in the absence of this niche bacteria are more efficiently killed by infiltrating neutrophils. This hypothesis will be tested in Specific Aim 2. Recent evidence indicates the existence of a novel population of lysozyme-expressing dendritic cells unique to the Peyer's patch, that are the first cells targeted by Salmonella upon transiting the intestinal epithelium. However nothing is known about the role of these cells in Salmonella infection. Characterization of these cells forms the basis for Specific Aim 3. Together, the results of these studies will provide significant new insight into the mechanisms used by Salmonella to infect their animal hosts, and the role of the innate immune response in combating the infection. The molecular details that emerge from these studies may provide new targets for next generation antibiotics or therapies for the prevention of Salmonellosis. PUBLIC HEALTH RELEVANCE: Infection with pathogenic Salmonella strains causes symptoms ranging from gastritis to potentially fatal systemic disease such as Typhoid Fever. The goals of this research are to define the host cell machinery that is subverted by Salmonella to enter the intestinal epithelium and spread systemically, and to characterize the innate immune responses to Salmonella infection.

描述（由申请人提供）：沙门氏菌通过进入并穿过肠上皮屏障来感染动物宿主。上皮的穿透主要是通过使用一组通过III型分泌装置分泌的效应分子直接侵入宿主上皮细胞来实现的。 SipC 构成该装置尖端的一部分，具有长的细胞质 N 端和 C 端，它们使细菌吞噬所需的肌动蛋白丝网络组装成核。使用酵母双杂交筛选，我们鉴定了许多与 SipC C 末端选择性相互作用的宿主蛋白。这些包括调节肌动蛋白组装和动力学的蛋白质，以及介导囊泡运输的蛋白质。我们假设沙门氏菌使用 SipC 在细菌附着位点使信号和细胞骨架机械的组装成核，以协调肌动蛋白重塑与新膜的递送以形成新生的吞噬体。这一假设将在具体目标 1 中进行探讨。沙门氏菌感染会触发炎症单核细胞向肠道的募集，这在清除感染方面发挥着重要作用。然而，沙门氏菌也可以利用吞噬细胞作为其全身传播的载体，宿主反应的成败取决于这两个过程之间的平衡。我们正在研究粘着斑激酶 (FAK) 在单核细胞迁移和功能中的作用。使用髓系细胞中条件性缺乏 FAK 的小鼠，我们发现，在缺乏 FAK 的情况下，炎症巨噬细胞向派尔氏淋巴结和肠系膜淋巴结的浸润受到损害，并且令人惊讶的是，这与所有检查组织的细菌定植减少有关。相反，中性粒细胞向同一组织的浸润增强，表明巨噬细胞和中性粒细胞向感染组织募集的调节存在差异。我们假设炎症巨噬细胞通过为细菌复制和传播提供保护性生态位，对于组织微环境中细菌的生存是必需的，并且在没有这种生态位的情况下，细菌会被浸润的中性粒细胞更有效地杀死。这一假设将在具体目标 2 中得到检验。最近的证据表明，派尔氏集结特有的表达溶菌酶的树突状细胞的新群体的存在，它们是沙门氏菌在通过肠上皮时首先靶向的细胞。然而，对于这些细胞在沙门氏菌感染中的作用尚不清楚。这些细胞的表征构成了特定目标 3 的基础。 总之，这些研究的结果将为沙门氏菌感染动物宿主的机制以及先天免疫反应在对抗感染中的作用提供重要的新见解。这些研究得出的分子细节可能为下一代抗生素或预防沙门氏菌病的疗法提供新靶点。 公共卫生相关性：致病性沙门氏菌菌株感染会引起从胃炎到伤寒等潜在致命的全身性疾病等症状。这项研究的目标是确定被沙门氏菌破坏进入肠上皮并全身传播的宿主细胞机制，并表征对沙门氏菌感染的先天免疫反应。

项目成果

Invasion of host cells by Salmonella typhimurium requires focal adhesion kinase and p130Cas.

• DOI: 10.1091/mbc.e06-06-0492
• 发表时间: 2006-11
• 期刊: Molecular biology of the cell
• 影响因子: 3.3
• 作者: Jing-Hua Shi;J. Casanova

Bacterial Autophagy: Offense and Defense at the Host-Pathogen Interface.

• DOI: 10.1016/j.jcmgh.2017.05.002
• 发表时间: 2017-09
• 期刊: Cellular and molecular gastroenterology and hepatology
• 影响因子: 7.2
• 作者: Casanova JE