Is there a placental microbiota? A critical review and re-analysis of published placental microbiota datasets

BMC Microbiology

article

Panzer, Jonathan J.¹  Romero, Roberto¹  Greenberg, Jonathan M.¹  Winters, Andrew D.¹  Galaz, Jose¹  Gomez-Lopez, Nardhy¹  Theis, Kevin R.¹ 

[1]Pregnancy Research Branch, Division of Obstetrics and Maternal-Fetal Medicine, Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, U.S. Department of Health and Human Services

[2]Department of Biochemistry, Microbiology, and Immunology, Wayne State University School of Medicine

[3]Department of Obstetrics and Gynecology, University of Michigan

[4]Department of Epidemiology and Biostatistics, Michigan State University

[5]Center for Molecular Medicine and Genetics, Wayne State University

[6]Detroit Medical Center

[7]Department of Obstetrics and Gynecology, Wayne State University School of Medicine

[8]Division of Obstetrics and Gynecology, School of Medicine, Faculty of Medicine, Pontificia Universidad Catolica de Chile

关键词: 16S rRNA gene sequencing;    Low microbial biomass sampling;    Microbiome;    Placenta;    Sterile womb;   

DOI  :  10.1186/s12866-023-02764-6

学科分类：放射科、核医学、医学影像

来源: BioMed Central

【 摘 要 】

The existence of a placental microbiota is debated. The human placenta has historically been considered sterile and microbial colonization was associated with adverse pregnancy outcomes. Yet, recent DNA sequencing investigations reported a microbiota in typical human term placentas. However, this detected microbiota could represent background DNA or delivery-associated contamination. Using fifteen publicly available 16S rRNA gene datasets, existing data were uniformly re-analyzed with DADA2 to maximize comparability. While Amplicon Sequence Variants (ASVs) identified as Lactobacillus, a typical vaginal bacterium, were highly abundant and prevalent across studies, this prevalence disappeared after applying likely  DNA contaminant removal to placentas from term cesarean deliveries. A six-study sub-analysis targeting the 16S rRNA gene V4 hypervariable region demonstrated that bacterial profiles of placental samples and technical controls share principal bacterial ASVs and that placental samples clustered primarily by study origin and mode of delivery. Contemporary DNA-based evidence does not support the existence of a placental microbiota.Importance Early-gestational microbial influences on human development are unclear. By applying DNA sequencing technologies to placental tissue, bacterial DNA signals were observed, leading some to conclude that a live bacterial placental microbiome exists in typical term pregnancy. However, the low-biomass nature of the proposed microbiome and high sensitivity of current DNA sequencing technologies indicate that the signal may alternatively derive from environmental or delivery-associated bacterial DNA contamination. Here we address these alternatives with a re-analysis of 16S rRNA gene sequencing data from 15 publicly available placental datasets. After identical DADA2 pipeline processing of the raw data, subanalyses were performed to control for mode of delivery and environmental DNA contamination. Both environment and mode of delivery profoundly influenced the bacterial DNA signal from term-delivered placentas. Aside from these contamination-associated signals, consistency was lacking across studies. Thus, placentas delivered at term are unlikely to be the original source of observed bacterial DNA signals.

【 授权许可】

CC BY|CC0