A bacterial biosensor for intracellular metal availability in the gut

用于肠道内细胞内金属可用性的细菌生物传感器

• 批准号: 10763683
• 负责人: Leigh Knodler
• 金额: $ 20.01万
• 依托单位: UNIVERSITY OF VERMONT & ST AGRIC COLLEGE
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-04-22 至 2024-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10763683
• 关键词: bacterial; biosensor; intracellular; metal; availability

PROJECT SUMMARY Of the foodborne bacterial, protozoal and viral diseases, non-typhoidal Salmonella enterica cause the largest burden of illness and death worldwide. The most common human clinical isolates are Salmonella enterica serovars Typhimurium (S. Typhimurium, STm) and Enteriditis (S. Enteriditis). Infection can cause either a self- limiting gastroenteritis or a life-threatening, invasive disease in immunocompromised individuals. During enteric infection, STm adopts both extracellular and intracellular lifestyles, colonizing the intestinal lumen as well epithelial cells and phagocytes in the intestinal mucosa. Here we will study how host-mediated restriction of transition metals, known as nutritional immunity, affects STm colonization of the gut. The NRAMP family of proteins are “promiscuous” transporters of divalent cations that play a major role in metal ion homeostasis from bacteria to man. In mammals, there are two NRAMP genes, SLC11A1 and SLC11A2 in humans and Slc11a1 and Slc11a2 in mice. Slc11a1 is restricted to the myeloid lineage whereas Slc11a2 is ubiquitously expressed. Whilst the role of Slc11a1 in controlling intracellular bacterial and parasitic infections in macrophages and mice is undisputed, whether Slc11a2 also contributes to antimicrobial functions is unknown. Our general hypothesis is that intracellular metal ion availability differs in epithelial cells and phagocytes in the gut due to the distinct cell-type expression of SLC11A1 and SLC11A2. First, we will use microbial biosensors of metal ion concentrations to infect bovine ligated ileal loops, a highly relevant model of enteric salmonellosis in humans, and map the spatiotemporal distribution of metal ion deprivation in the gut. Second, we will define whether SLC11A2, the sole NRAMP family member expressed in intestinal epithelial cells, defends against invading pathogens via metal nutrient limitation. Completion of this proposal will close a significant knowledge gap about host-microbe competition for metal ions in the gut during enteric infection.

项目概要 在食源性细菌、原虫和病毒性疾病中，非伤寒沙门氏菌引起的疾病最多 全世界疾病和死亡的负担。最常见的人类临床分离株是肠沙门氏菌 血清型鼠伤寒（S. Typhimurium，STm）和肠炎（S. Enteriditis）。感染可能导致自我 限制免疫功能低下个体的胃肠炎或危及生命的侵袭性疾病。肠溶期间 感染后，STm 采用细胞外和细胞内的生活方式，也在肠腔内定殖 肠粘膜中的上皮细胞和吞噬细胞。在这里，我们将研究宿主介导的限制如何 过渡金属被称为营养免疫，影响 STm 在肠道的定植。 NRAMP 家族 蛋白质是二价阳离子的“混杂”转运蛋白，在金属离子稳态中发挥着重要作用 细菌对人来说。在哺乳动物中，有两个 NRAMP 基因，在人类中为 SLC11A1 和 SLC11A2，在人类中为 SLC11a1 和小鼠中的 Slc11a2。 Slc11a1 仅限于骨髓谱系，而 Slc11a2 则普遍表达。 Slc11a1 在控制巨噬细胞和小鼠细胞内细菌和寄生虫感染中的作用 毫无争议，Slc11a2 是否也有助于抗菌功能尚不清楚。我们的一般假设 肠道中的上皮细胞和吞噬细胞的细胞内金属离子可用性不同，这是由于不同的 SLC11A1 和 SLC11A2 的细胞类型表达。首先，我们将使用金属离子的微生物生物传感器 感染牛结扎回肠环的浓度，这是人类肠道沙门氏菌病的高度相关模型， 并绘制肠道内金属离子剥夺的时空分布图。其次，我们将定义是否 SLC11A2 是肠上皮细胞中表达的唯一 NRAMP 家族成员，可防御入侵 通过金属营养限制来抑制病原体。完成该提案将弥补以下方面的重大知识差距： 肠道感染期间宿主与微生物对肠道中金属离子的竞争。