Innate immunity and Salmonella pathogenesis

先天免疫和沙门氏菌发病机制

• 批准号: 8786055
• 负责人: Gregory M Barton
• 金额: $ 35.27万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-01-18 至 2015-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8786055
• 关键词: Alleles; Animals; Backcrossings; Cells; Dependence; Disease; Disease Outbreaks; Environment; Foundations; Generations; Genes; Gentamicins; Goals; Grant; Growth; Health; Image; Immune system; Inbred Strains Mice; Intestines; Knock-in Mouse; Manuscripts; Masks; Measures; Modeling; Mouse Strains; Mus; Mutate; Natural Immunity; Oral; Pathogenesis; Phagosomes; Predisposition; Publishing; Receptor Signaling; Research; Role; Route; Salmonella; Salmonella infections; Salmonella typhimurium; Site; Systemic infection; TLR4 gene; Testing; Time; Toll-Like Receptor 1; Toll-like receptors; Vacuole; Virulence; Virulent; base; cell type; divalent metal; foodborne; gene induction; in vivo; intraperitoneal; macrophage; oral infection; pathogen; receptor function

DESCRIPTION (provided by applicant): This application seeks to understand how the innate immune system influences the pathogenesis of Salmonella typhimurium. We are studying this issue by examining Salmonella virulence in mice and cells deficient in Toll- like receptors (TLRs). To unmask potentially critical host-pathogen interactions in this model, we have generated these TLR-deficient strains with a functional allele of Nramp-1, a divalent metal transporter that is mutated in many inbred mouse strains. Lack of functional Nramp-1 renders mice extremely susceptible to intracellular pathogens. Using these mouse strains we have made the surprising discovery that TLR- dependent phagosome acidification is required for induction of SPI-2 virulence genes. Thus, in macrophages lacking most or all TLR signaling, Salmonella is unable to create a replicative compartment. Surprisingly, this requirement for TLR signaling is only evident in cells with functional Nramp-1, suggesting that both TLRs and Nramp-1 manipulate the phagosomal environment. Salmonella is less virulent in mice lacking some, but not all, TLR signaling, consistent with an inability to replicate in macrophages. However, mice completely lacking TLR signaling are quite susceptible to Salmonella, suggesting that Salmonella is somehow able to cause disease in these animals without replicating in macrophages. The Aims of this grant focus on understanding how Nramp-1 and TLRs influence the niche where Salmonella replicates. In Aim 1, we will examine how Nramp-1 influences the phagosomal environment in the absence of TLR signaling. In Aim 2, we will examine how the level of TLR signaling can influence where Salmonella replicates in vivo. In Aim 3, we will exploit Salmonella's requirement for TLR signaling in mice with reduced TLR function. This requirement will be used to identify key cell types in which Salmonella must replicate while spreading systemically from intestinal sites.

描述（由申请人提供）：本申请旨在了解先天免疫系统如何影响鼠伤寒沙门氏菌的发病机制。我们正在通过检查小鼠和缺乏 Toll 样受体 (TLR) 的细胞中沙门氏菌的毒力来研究这个问题。为了揭示该模型中潜在的关键宿主-病原体相互作用，我们生成了这些具有 Nramp-1 功能等位基因的 TLR 缺陷品系，Nramp-1 是一种二价金属转运蛋白，在许多近交系小鼠品系中发生突变。缺乏功能性 Nramp-1 使小鼠极易受到细胞内病原体的影响。使用这些小鼠品系，我们令人惊讶地发现，TLR 依赖性吞噬体酸化是诱导 SPI-2 毒力基因所必需的。因此，在缺乏大部分或全部 TLR 信号传导的巨噬细胞中，沙门氏菌无法创建复制区室。令人惊讶的是，这种对 TLR 信号传导的要求仅在具有功能性 Nramp-1 的细胞中明显，这表明 TLR 和 Nramp-1 都操纵吞噬体环境。沙门氏菌在缺乏部分（但不是全部）TLR 信号传导的小鼠中毒性较低，这与无法在巨噬细胞中复制一致。然而，完全缺乏 TLR 信号传导的小鼠对沙门氏菌非常敏感，这表明沙门氏菌以某种方式能够在这些动物中引起疾病​​，而无需在巨噬细胞中复制。这笔资助的目的重点是了解 Nramp-1 和 TLR 如何影响沙门氏菌复制的生态位。在目标 1 中，我们将研究在没有 TLR 信号传导的情况下 Nramp-1 如何影响吞噬体环境。在目标 2 中，我们将研究 TLR 信号传导水平如何影响沙门氏菌在体内的复制位置。在目标 3 中，我们将利用 TLR 功能降低的小鼠中沙门氏菌对 TLR 信号传导的需求。这一要求将用于识别沙门氏菌在从肠道部位全身传播时必须在其中复制的关键细胞类型。