Liu Liping, Yin Tingting, Zhang Xin, Sun Lizhou, Yin Yin
Department of Obstetrics and Gynecology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
Am J Reprod Immunol. 2024 Dec;92(6):e70023. doi: 10.1111/aji.70023.
Previously believed sterile, the placenta hosts distinct microbial species across various locations. This study aims to elucidate the temporal and spatial variations of placental microbiota throughout gestation, addressing gaps in current understanding.
A case-control study at a single-center compared microbial profiles in pregnant women delivering preterm (<37 weeks) or at term (>37 weeks) across placental sites: basal plate, fetal membranes, and placental villous. Microbial abundance and diversity were evaluated using QIIME and the R package "Phyloseq," while Q-PCR with specific primers validated absolute abundance in samples.
We found no alteration in bacterial communities based on delivery mode across all samples. Q-PCR detected low-abundance bacteria, notably enriched in preterm samples, especially in early preterm cases. Throughout gestation, bacterial composition varied, with increasing levels of Proteobacteria and Firmicutes observed in the placenta. Significant differences in bacterial profiles were noted across locations and gestational stages, with Ralstonia insidiosa consistently present in the basal plate throughout gestation. Species-specific Q-PCR confirmed the presence of Ralstonia and revealed an inverse relationship between Streptococcus agalactiae and pregnancy progression.
The placenta hosts its own microbiome, with distinct profiles observed between term and preterm samples. Further research is needed to clarify the impact of bacterial dysbiosis on preterm birth and develop methods to distinguish pathological bacteria from the natural microbiome.
胎盘以前被认为是无菌的，但在不同位置存在着不同的微生物种类。本研究旨在阐明整个孕期胎盘微生物群的时空变化，填补当前认知中的空白。
一项单中心病例对照研究比较了早产（<37周）或足月产（>37周）孕妇胎盘不同部位（基底板、胎膜和胎盘绒毛）的微生物谱。使用QIIME和R包“Phyloseq”评估微生物丰度和多样性，同时用特异性引物进行定量聚合酶链反应（Q-PCR）验证样本中的绝对丰度。
我们发现所有样本中基于分娩方式的细菌群落没有变化。Q-PCR检测到低丰度细菌，在早产样本中显著富集，尤其是早期早产病例。在整个孕期，细菌组成发生变化，胎盘内变形菌门和厚壁菌门的水平升高。不同位置和妊娠阶段的细菌谱存在显著差异，妊娠期间基底板中始终存在内侧罗尔斯通氏菌。物种特异性Q-PCR证实了内侧罗尔斯通氏菌的存在，并揭示了无乳链球菌与妊娠进展之间的负相关关系。
胎盘有其自身的微生物群，足月和早产样本之间观察到不同的特征。需要进一步研究以阐明细菌失调对早产的影响，并开发区分病理细菌与天然微生物群的方法。
