Seman Brittany G, Povroznik Jessica M, Vance Jordan K, Rawson Travis W, Robinson Cory M
Department of Microbiology, Immunology, & Cell Biology, West Virginia University School of Medicine.
Department of Microbiology, Immunology, & Cell Biology, West Virginia University School of Medicine; Vaccine Development Center at West Virginia University Health Sciences Center.
J Vis Exp. 2020 Aug 12(162). doi: 10.3791/61609.
Neonates are at an increased risk of bacterial sepsis due to the unique immune profile they display in the first months of life. We have established a protocol for studying the pathogenesis of E. coli O1:K1:H7, a serotype responsible for high mortality rates in neonates. Our method utilizes intravital imaging of neonatal pups at different time points during the progression of infection. This imaging, paralleled by measurement of bacteria in the blood, inflammatory profiling, and tissue histopathology, signifies a rigorous approach to understanding infection dynamics during sepsis. In the current report, we model two infectious inoculums for comparison of bacterial burdens and severity of disease. We find that subscapular infection leads to disseminated infection by 10 h post-infection. By 24 h, infection of luminescent E. coli was abundant in the blood, lungs, and other peripheral tissues. Expression of inflammatory cytokines in the lungs is significant at 24 h, and this is followed by cellular infiltration and evidence of tissue damage that increases with infectious dose. Intravital imaging does have some limitations. This includes a luminescent signal threshold and some complications that can arise with neonates during anesthesia. Despite some limitations, we find that our infection model offers an insight for understanding longitudinal infection dynamics during neonatal murine sepsis, that has not been thoroughly examined to date. We expect this model can also be adapted to study other critical bacterial infections during early life.
由于新生儿在生命最初几个月所展现出的独特免疫特征，他们患细菌性败血症的风险更高。我们已经建立了一种研究大肠杆菌O1:K1:H7发病机制的方案，该血清型是导致新生儿高死亡率的原因。我们的方法利用了在感染过程中不同时间点对新生幼崽进行的活体成像。这种成像，再结合血液中细菌的测量、炎症分析和组织病理学检查，标志着一种严谨的方法来理解败血症期间的感染动态。在本报告中，我们模拟了两种感染接种物，以比较细菌载量和疾病严重程度。我们发现，肩胛下感染在感染后10小时会导致播散性感染。到24小时时，发光大肠杆菌在血液、肺和其他外周组织中大量存在。肺部炎症细胞因子的表达在24小时时显著，随后是细胞浸润和组织损伤的迹象，且随着感染剂量的增加而加重。活体成像确实有一些局限性。这包括发光信号阈值以及新生儿在麻醉期间可能出现的一些并发症。尽管有一些局限性，但我们发现我们的感染模型为理解新生儿小鼠败血症期间的纵向感染动态提供了见解，而这一点迄今为止尚未得到充分研究。我们期望这个模型也能适用于研究生命早期的其他严重细菌感染。
