Data from: Changes in the bacterial microbiota in gut, blood, and lungs following acute LPS instillation into mice lungs

Introduction: Previous reports have shown that the gastrointestinal (GI) bacterial microbiota can have profound effects on the lungs, which has been described as the “gut-lung axis”. However, whether a “lung-gut” axis exists wherein acute lung inflammation perturbs the gut and blood microbiota is unknown. Methods: Adult C57/Bl6 mice were exposed to one dose of LPS or PBS instillation (n = 3 for each group) directly into lungs. Bacterial microbiota of the bronchoalveolar lavage fluid, blood, and cecum were determined using 454 pyrotag sequencing and quantitative polymerase chain reaction (qPCR) at 4 through 168 hours post-instillation. We then investigated the effects of oral neomycin and streptomycin (n = 8) on the microbiota at 4 and 24 hours post LPS instillation versus control treatment (n = 5 at baseline and 4 hours, n = 7 at 24 hours). Results: At 24 hours post LPS instillation, the total bacterial count was significantly increased in the cecum (P<0.05); whereas the total bacterial count in blood was increased at 4, 48, and 72 hours (P<0.05). Antibiotic treatment reduced the total bacteria in blood but not in the cecum. The increase in total bacteria in the blood correlated with Phyllobacteriaceae OTU 40 and was significantly reduced in the blood for both antibiotic groups (P<0.05). Conclusion: LPS instillation in lungs leads to acute changes in the bacterial microbiota in the blood and cecum, which can be modulated with antibiotics.

引言：过往研究表明，胃肠道（gastrointestinal, GI）细菌菌群可对肺部产生显著影响，该现象被称为“肠-肺轴（gut-lung axis）”。然而，是否存在“肺-肠轴（lung-gut axis）”，即急性肺部炎症是否会扰乱肠道与血液菌群，目前尚无定论。
方法：将成年C57/Bl6小鼠经气道直接滴注单次剂量的脂多糖（LPS）或磷酸盐缓冲液（PBS），每组各3只。分别于滴注后4小时至168小时，采用454焦磷酸测序与定量聚合酶链式反应（qPCR）检测支气管肺泡灌洗液、血液及盲肠的细菌菌群组成。随后，我们设置口服新霉素与链霉素处理组（n=8）与对照组（基线及4小时组n=5，24小时组n=7），探究二者对LPS滴注后4小时及24小时小鼠菌群的调控效果。
结果：LPS滴注后24小时，小鼠盲肠的细菌总载量显著升高（P<0.05）；而血液中的细菌总载量则在滴注后4、48及72小时均显著升高（P<0.05）。抗生素处理可降低血液中的细菌总载量，但对盲肠菌群无显著影响。血液中细菌总载量的升高与叶杆菌科（Phyllobacteriaceae）操作分类单元（operational taxonomic unit, OTU）40呈显著相关，且两种抗生素处理组的血液该类菌群丰度均显著降低（P<0.05）。
结论：经气道滴注LPS可诱导血液与盲肠的细菌菌群发生急性变化，该变化可通过抗生素进行调控。