Nutritional immunity and microbial competition during Clostridioides difficile infection

艰难梭菌感染期间的营养免疫和微生物竞争

• 批准号: 10643887
• 负责人: Eric P Skaar
• 金额: $ 47.05万
• 依托单位: VANDERBILT UNIVERSITY MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-06-13 至 2027-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10643887
• 关键词: Affect; Antibiotic Therapy; Antibiotics; Bacteroides; Binding; Binding Proteins; Biological Markers; Cells; Clinical; Clostridium difficile; Complex; Data; Development; Dietary Zinc; Event; Gastrointestinal tract structure; Gene Expression; Genes; Genetically Modified Animals; Growth; Human; Immune; Immune system; Immunologic Factors; Incidence; Individual; Infection; Infiltration; Inflammation; Inflammatory; Inflammatory Response; Iron; Knowledge; Lead; Leukocyte L1 Antigen Complex; Manganese; Mediating; Metal exposure; Metals; Microbe; Modeling; Molecular; Mus; Names; Nutrient; Nutrient availability; Nutritional; Nutritional Immunity; Outcome; Pathogenesis; Pattern; Physiology; Play; Predisposition; Prevention strategy; Process; Production; Property; Proteins; Public Health; Recurrent disease; Reproduction spores; Research; Role; Severities; Shapes; Site; Starvation; System; Testing; Toxin; Trace metal; Up-Regulation; Vertebrates; Zinc; cell type; chelation; chemokine; cofactor; colonization resistance; cost; cytokine; defined contribution; dietary; dietary excess; enteric infection; enteric pathogen; experimental study; gastrointestinal epithelium; gene product; gut colonization; gut microbiota; host-microbe interactions; human microbiota; immunoregulation; member; microbial; microbial community; microbiome; microbiota; neutrophil; normal microbiota; nutrient deprivation; pathogen; prevent; programs; recruit; response; therapeutic development; therapeutically effective; transcriptional reprogramming; treatment strategy; young adult

SUMMARY Clostridioides difficile (formerly named Clostridium difficile) is a Gram-positive, spore-forming pathogen, and the leading cause of nosocomial and antibiotic-associated intestinal infections. Susceptibility to C. difficile infection (CDI) often follows antibiotic treatment and subsequent disruption of the resident intestinal microbiota, however the rise of infections in healthy young adults suggests that there are additional factors that contribute to CDI. To colonize the gastrointestinal tract, C. difficile must compete with both the host and members of the gut microbiota for critical nutrients. Access to nutrient metals can profoundly impact the outcome of CDI as metals are required cofactors for approximately 30% of all proteins. This fact is exploited by host metal binding proteins which sequester nutrient metals to restrict microbial growth in a process termed nutritional immunity. A hallmark of CDI is the secretion of potent toxins that cause severe damage to the gastrointestinal epithelium and trigger the production of pro-inflammatory cytokines and chemokines. These events initiate the immune-mediated recruitment of inflammatory factors to the site of infection. One of the most abundant inflammatory proteins that accumulates at the site of CDI is calprotectin. Calprotectin is the most abundant protein in neutrophils and is a component of nutritional immunity that directly inhibits microbial growth through nutrient metal sequestration. Calprotectin is also a potent immunomodulatory protein, and a common clinical inflammatory biomarker whose abundance correlates with CDI severity. It is unknown how the massive infiltration of calprotectin affects metal availability in the gastrointestinal tract and shapes competition between C. difficile and members of the gut microbiota. In addition, how C. difficile adapts to calprotectin-dependent metal limitation and resists nutritional immunity during CDI remains unclear. We propose a model whereby nutrient metals make a critical contribution to the outcome of CDI. Toxin driven inflammation drives the recruitment of immune cells into the gut which leads to the accumulation of large amounts of CP. CP chelates available nutrient metals and exerts potent pro- inflammatory activities. This massive inflammatory response and redistribution of nutrients alters C. difficile gene expression and affects the interaction between C. difficile and members of the microbiota. Finally, we hypothesize that C. difficile encodes multiple gene products that compete with both CP and the microbiota for nutrient metals and this competition has a profound effect on the outcome of CDI. Experiments described in this proposal will test this model and define the contribution of nutritional immunity to the pathogenesis of C. difficile, determine the role of metal binding and immune cell recruitment in the protective properties of calprotectin, and identify C. difficile genes required to compete with the microbiome for nutrient metals during inflammation. Collectively, the findings from this proposal will inform the development of effective therapeutic or prevention strategies for the treatment of CDI.

概括 艰难梭菌（以前称为艰难梭菌）是一种革兰氏阳性、形成孢子的病原体， 院内感染和抗生素相关肠道感染的主要原因。对艰难梭菌感染的易感性 （CDI）通常发生在抗生素治疗和随后的肠道常驻微生物群破坏之后，然而 健康年轻人感染率的上升表明还有其他因素导致 CDI。到 艰难梭菌定植于胃肠道，必须与宿主和肠道微生物群成员竞争 对于关键营养素。由于需要金属，获取营养金属可以深刻影响 CDI 的结果 大约 30% 的蛋白质的辅因子。这一事实被宿主金属结合蛋白利用， 在称为营养免疫的过程中隔离营养金属以限制微生物生长。 CDI 的标志 是强效毒素的分泌，对胃肠道上皮造成严重损害并引发 促炎细胞因子和趋化因子的产生。这些事件启动了免疫介导的 将炎症因子募集到感染部位。最丰富的炎症蛋白之一 在 CDI 部位积聚的是钙卫蛋白。钙卫蛋白是中性粒细胞中最丰富的蛋白质，是一种 营养免疫的组成部分，通过营养金属螯合直接抑制微生物生长。 钙卫蛋白也是一种有效的免疫调节蛋白，也是一种常见的临床炎症生物标志物， 丰度与 CDI 严重程度相关。目前尚不清楚钙卫蛋白的大量渗透如何影响金属 胃肠道中的可用性并形成艰难梭菌和肠道成员之间的竞争 微生物群。此外，艰难梭菌如何适应钙卫蛋白依赖性金属限制并抵抗营养 CDI 期间的免疫力仍不清楚。我们提出了一个模型，其中营养金属做出了关键贡献 CDI 的结果。毒素驱动的炎症会促使免疫细胞招募到肠道中，从而导致 大量CP的积累。 CP 螯合可用的营养金属并发挥有效的促进作用 炎症活动。这种大规模的炎症反应和营养物质的重新分配改变了艰难梭菌基因 表达并影响艰难梭菌和微生物群成员之间的相互作用。最后，我们 假设艰难梭菌编码多种基因产物，这些基因产物与 CP 和微生物群竞争 营养金属和这种竞争对 CDI 的结果有深远的影响。本文描述的实验 该提案将测试该模型并确定营养免疫对艰难梭菌发病机制的贡献， 确定金属结合和免疫细胞募集在钙卫蛋白保护特性中的作用，以及 识别炎症期间与微生物组竞争营养金属所需的艰难梭菌基因。 总的来说，该提案的研究结果将为有效治疗或预防的开发提供信息 CDI 的治疗策略。