PM2.5暴露荷瘤裸鼠后肠道菌群组成的改变

目的了解暴露PM_(2.5)后的Bac荷瘤裸鼠肠道菌群组成的变化。方法采用A549细胞对30只Bac裸鼠进行肺内注射,饲养1周适应环境,第2周开始进行暴露染尘与对照暴露生理盐水组实验,共暴露1、4、8周。采用口鼻暴露仓进行小鼠染尘与生理盐水暴露操作,每周暴露6d,每天2h,建立大气污染暴露荷瘤裸鼠模型,5只未做处理的Bac荷瘤裸鼠作为空白对照组。采集裸鼠晨起新鲜粪便样品,抽提其中微生物总基因组DNA,采用Ⅱ代基因测序技术对粪便样品进行16S高变区扩增测序,划分可操作分类单元(operational taxonomic unit,OTU),使用I-Sanger分析平台对所有OTU进行物种注释与评估、物种组成分析、样本比较分析等,运用R Studio软件对数据进行统计学分析。结果厚壁菌门和拟杆菌门在PM_(2.5)暴露组、生理盐水对照组和空白对照组均为最优势菌门。PM_(2.5)暴露组与生理盐水对照组及空白对照组相比厚壁菌门减少,拟杆菌门增加。结论 PM_(2.5)暴露减少Bac荷瘤裸鼠肠道菌群丰度,破坏肠道菌群平衡,在一定程度上可抑制有益菌的繁殖,并使致病菌数量增加。

Changes of intestinal flora in nude mice exposed to PM2.5

Abstract: Objective To understand the changes of intestinal flora of Bac tumor bearing nude mice exposed to PM2.5. Methods A549 cells were injected into the lungs of 30 Bac nude mice. After adaption to environment for one week, the mice were exposed to dust or normal saline, 2 hours daily, 6 days a week. Five untreated tumor bearing nude mice were used as blank controls. Samples of fresh feces were collected in morning to extract the total genomic DNA of microbes. The 16S hypervariable region of fecal samples was sequenced by using the 2nd generation gene sequencing to define the operational taxonomic units (OTUs). The species annotation and evaluation, species composition analysis and sample comparison analysis of all OTUs were performed using I-Sanger analysis platform, and statistical analysis of data was performed using R Studio software. Results In PM2.5 group, saline control group and blank control group, Firmicutes and Bacteroidetes were the most dominant phyla. Compared with the normal saline control group and blank control group, the abundance of Firmicutes reduced while that of Bacteroidetes increased in PM2.5 group. Conclusion PM2.5 exposure reduced the abundance of intestinal microflora in nude mice bearing Bac tumor, disrupted the balance of intestinal flora, inhibited the propagation of beneficial bacteria to some extent, and increased the number of pathogenic bacteria.