High-throughput 16S rRNA gene sequencing reveals alterations of mouse intestinal microbiota after radiotherapy

The mammalian gastrointestinal tract harbors a highly complex microbial community that comprises hundreds of different types of bacterial cells. The gastrointestinal microbiota plays an important role in the function of the host intestine. Most cancer patients undergoing pelvic irradiation experience side effects such as diarrhea; however, little is currently known about the effects of irradiation on the microorganisms colonizing the mucosal surfaces of the gastrointestinal tract. The aim of this study was to investigate the effects of gamma irradiation on the compositions of the large and small intestinal microbiotas. The gut microbiotas in control mice and mice receiving irradiation treatment were characterized by high-throughput sequencing of the bacterial 16S rRNA gene. Irradiation treatment induced significant alterations in the bacterial compositions of the large and small intestines at the genus level. Unexpectedly, irradiation treatment increased the number of operational taxonomic units in the small intestine but not the large intestine. In particular, irradiation treatment increased the level of the genera Alistipes in the large intestine and increased the level of the genus Corynebacterium in the small intestine. By contrast, compared with that in the corresponding control group, the level of the genera Prevotella was lower in the irradiated large intestine, and the level of the genera <i>Alistipes</i> was lower in the irradiated small intestine. Overall, the data presented here reveal the potential microbiological effects of pelvic irradiation on the gastrointestinal tracts of cancer patients.

哺乳动物胃肠道内定植着高度复杂的微生物群落，其中包含数百种不同的细菌细胞。胃肠道微生物群（gastrointestinal microbiota）对宿主肠道的生理功能发挥着关键作用。多数接受盆腔放射治疗的癌症患者会出现腹泻等不良反应，但目前学界对辐射作用于胃肠道黏膜表面定植微生物的影响尚不清楚。本研究旨在探究伽马辐射（gamma irradiation）对大肠与小肠微生物群组成的影响。本研究通过细菌16S核糖体RNA基因（16S rRNA gene）高通量测序（high-throughput sequencing）技术，对对照组小鼠与接受辐射处理小鼠的肠道微生物群进行了表征分析。辐射处理会在属水平上显著改变大肠与小肠的细菌群落组成。出乎意料的是，辐射处理会增加小肠内的操作分类单元（operational taxonomic units, OTU）数量，但对大肠无此影响。具体而言，辐射处理会提升大肠内别样杆菌属（Alistipes）的相对丰度，并增加小肠内棒状杆菌属（Corynebacterium）的相对丰度。与之相对，与相应对照组相比，辐射处理后的大肠内普雷沃菌属（Prevotella）的相对丰度有所降低，而辐射处理后的小肠内别样杆菌属（Alistipes）的相对丰度同样下降。总体而言，本研究呈现的数据揭示了盆腔辐射对癌症患者胃肠道可能产生的微生物学影响。