Miseq sequencing 16S rRNA tagging reveals diverse intrauterine microbiomes in patients suffering with endometrial polyps. intrauterine microbiomes

Endometrial polyps (EP), whose etiology is unknown, may be related to chronic endometritis (CE) which is mainly caused by intrauterine infection on the basis of bacteria. However, so far there are no data to evaluate compositions and diversity of intrauterine microbiota in EP patients and the differences of intrauterine microbiota between EP patients and healthy women. In our study, we employed 16S rRNA gene sequencing to classify bacterial DNA and characterized the intrauterine microbiome from healthy women (Group H (I)), women with EP and CE (Group EP/CE (I)) as well as women with only EP (Group EP (I)). We found that intrauterine cavities of both healthy women and patients with EP were not sterile and presented diverse kinds of microbiota which differed greatly from vaginal microbiome. Among the three groups, three bacterial phyla, Proteobacteria, Firmicutes, Actinobacteria, dominated the intrauterine microbiota; however, the proportions of Firmicutes from Group EP/CE (I) and Group EP (I) were both much higher than that from Group H (I), while the proportions of Proteobacteria were far lower. Meanwhile, both the rarefaction curves and Shannon diversity index in Group EP/CE (I) were higher than those in Group H (I) and EP (I). PCoA plots based on the weighted UniFrac distance metric indicated clustering of samples among Groups H (I), EP/CE (I) and EP (I) (ANOSIM, p<0.001).When comparing the proportion of the uterine microbiome in Group H (I) by sequencing experiments, we found that the percentage of Lactobacillus, Gardnerella, Bifidobacterium, Streptococcus, and Alteromonas were higher, while Pseudomonas were lower in Group EP/CE (I) and EP (I). Meanwhile the patients in Group EP/CE (I) had a lower proportion of Enterobacter and Sphingomonas and a higher proportion of Prevotella. In conclusion, these data suggest that there are significantly different kinds of uterine microbiota between healthy women and women with EP. All of the potentially important uterine microbiota may cause uterine EP but are not definitively related to chronic endometritis. We recommend more advanced experiments be performed to prove these relationships.