Evaluation of the Human Placental Microbiota in Early- and Late-Onset Pre-Eclampsia.

Introduction: Despite many decades of research, the exact etiology of pre-eclampsia (PE) remains unknown. Several etiopathologies have been suggested, including the role of the placental microbiota. However, the existence of placental microbiota and its possible contribution to pregnancy complications, particularly PE has remained controversial.

Aim: The present study was designed to identify different microbes that co-exist the placenta of women with early- and late-onset PE.

Methods: Thirty age-matched normotensive and early-onset as well as age-matched normotensive and late-onset pre-eclamptic women respectively, were recruited. After obtaining an informed consent, the placental tissues were obtained through caesarian section with sterile and standardized clinical procedures. DNA was extracted from each tissue and microbiome analysis was conducted using a targeted 16 S analysis and the reads were analyzed with bioinformatics.

Results: There was a significance difference between the blood pressure of early-/late-onset PE compared with age-matched normotensive controls, respectively. In addition, the reads from placencental samples were classified as belonging to the phyla, Actinobacteria, Firmicutes, Bacteroidetes, Proteobacteria, with Proteobacteria dominated by the classes Pseudomonadales and Gammaproteobacteria with smaller amounts of Actinobacteria and Bacteroidetes. There was no significant difference between the placental bacterial species of early-/late-onset PE compared with age-matched normotensive controls, respectively. Further analysis found no correlation between bacterial species and early- or late-onset PE.

Conclusion: The present results demonstrate a low biomass of bacterial species, which might further indicate that the placental samples had very low levels of bacteria species and there is no correlation between the bacterial composition and early- or late-onset PE.