Fecal microbiota transplant rescues mice from sepsis

The aim of this study was to test the hypothesis that replenishing the microbiota with a fecal microbiota transplant (FMT) can rescue a host from an advanced stage of sepsis. We developed a clinically-relevant mouse model of lethal polymicrobial gut-derived sepsis in mice using a 4-member pathogen community (Candida albicans, Klebsiella oxytoca, Serratia marcescens, Enterococcus faecalis) isolated from a critically ill patient. In order to mimic pre-operative surgical patient condition mice were exposed to food restriction and antibiotics. Approximately 18 hours prior to surgery food was removed from the cages and the mice were allowed only tap water. Each mouse received an intramuscular Cefoxitin injection 30 minutes prior to the incision at a concentration of 25 mg/kg into the left thigh. Mice were then subjected to a midline laparotomy, 30% hepatectomy of the left lateral lobe of the liver and a direct cecal inoculation of 200 µL of the four pathogen community. On postoperative day one, the mice were administered rectal enema. Mice were given either 1 ml of fecal microbiota transplant (FMT) or an autoclaved control (AC). This was again repeated on postoperative day two. Mice were then followed for mortality. Chow was restored to the cages on postoperative day two, approximately 45 hours after the operation. The injection of fecal microbiota transplant by enema significantly protected mice survival, reversed the composition of gut microflora and down-regulated the host inflammatory response. The cecum, left lobe of the liver, and spleen were isolated from mice for microarray processing with three or more replicates for six expermental conditions: non-treated control, SAHC POD1, SAHC.AC POD2, SAHC.FMT POD2, SAHC.AC POD7, SAHC.FMT POD7

本研究旨在验证下述假说：粪便菌群移植（Fecal Microbiota Transplant, FMT）可帮助宿主渡过晚期脓毒症。我们利用从重症患者体内分离出的4种病原体群落（白色念珠菌（Candida albicans）、产酸克雷伯菌（Klebsiella oxytoca）、黏质沙雷菌（Serratia marcescens）、粪肠球菌（Enterococcus faecalis）），构建了与临床高度相关的致死性多菌型肠源性脓毒症小鼠模型。
为模拟外科术前患者的生理状态，小鼠接受了禁食与抗生素预处理：手术前约18小时移除笼内饲料，仅提供自来水。每只小鼠于皮肤切开前30分钟，于左侧大腿肌内注射浓度为25 mg/kg的头孢西丁（Cefoxitin）。随后对小鼠实施正中剖腹术、左外侧肝叶30%切除术，并直接向盲肠接种200 μL的上述四种病原体混合菌液。
术后第1天，对小鼠进行直肠灌肠给药。小鼠分别接受1 mL粪便菌群移植（FMT）或高压灭菌对照（Autoclaved Control, AC），该操作于术后第2天重复进行。随后持续跟踪记录小鼠的存活情况。术后第2天，即手术后约45小时，恢复笼内常规饲料供给。
实验结果显示，经灌肠给药的粪便菌群移植可显著提升小鼠存活率，逆转肠道菌群组成，并下调宿主炎症反应。我们从受试小鼠体内分离盲肠、左外侧肝叶与脾脏样本用于微阵列（Microarray）检测，共设置6组实验条件，每组设置3次及以上生物学重复：未处理对照组、SAHC POD1、SAHC.AC POD2、SAHC.FMT POD2、SAHC.AC POD7、SAHC.FMT POD7。