Using a Zebrafish Model to Identify Cellular Responses to Uropathogenic E. coli Bacteremia. Using a Zebrafish Model to Identify Cellular Responses to Uropathogenic E. coli Bacteremia

Urinary tract infections (UTIs) are the second most common infections encountered in the pediatric population, second only to respiratory tract infections. UTIs are also a major cause of morbidity and mortality. UTIs can often ascend causing infection in the upper urinary tract or even progress to bacteremia or urosepsis. Urosepsis accounts for 10-30% of septic shock cases and Uropathogenic E.coli (UPEC) is responsible for almost 75% of cases. Therefore, increased understanding of the effects of urosepsis at the cellular and organ specific level will provide the foundation for improvements in clinical care. Overall design: Two zebrafish cohorts were injected with either sterile saline or UPEC and subjected to scRNA-seq. Cell clusters were identified and subjected to RNA velocity analysis. Selected clusters relevant to the innate immune system and bactericidal activity underwent canonical pathway analysis. RNA velocity analysis revealed several key changes in the transcriptional state of UPEC infected cells and pathway analysis provided key information regarding changes in innate immune pathways within the cell clusters.

尿路感染（urinary tract infections, UTIs）是儿科人群中第二常见的感染性疾病，仅次于呼吸道感染。尿路感染亦是导致发病与死亡的重要因素，其通常可上行引发上尿路感染，甚至进展为菌血症或尿源性脓毒症（urosepsis）。尿源性脓毒症占脓毒性休克病例的10-30%，而尿路致病性大肠埃希菌（Uropathogenic E. coli, UPEC）则是近75%病例的致病病原体。因此，加深对尿源性脓毒症在细胞与器官特异性水平的致病效应的理解，将为临床诊疗水平的提升奠定坚实基础。
整体实验设计：将两组斑马鱼队列分别予以无菌生理盐水或尿路致病性大肠埃希菌注射，随后开展单细胞RNA测序（single-cell RNA sequencing, scRNA-seq）。对鉴定得到的细胞聚类群进行RNA速率（RNA velocity）分析；针对与先天免疫系统及杀菌活性相关的目标聚类群，实施经典通路分析。RNA速率分析揭示了尿路致病性大肠埃希菌感染细胞的转录状态存在多项关键变化，而经典通路分析则为细胞聚类群内先天免疫通路的变化提供了关键信息。