Abstract

With the important role of the gut microbiome in health and disease, it is crucial to understand key factors that establish the microbial community, including gut colonization during infancy. It has been suggested that the first bacterial exposure is via a placental microbiome. However, despite many publications, the robustness of the evidence for the placental microbiome and transfer of bacteria from the placenta to the infant gut is unclear and hence the concept disputed. Therefore, we conducted a systematic review of the evidence for the role of the placental, amniotic fluid and cord blood microbiome in healthy mothers in the colonization of the infant gut. Most of the papers which were fully assessed considered placental tissue, but some studied amniotic fluid or cord blood. Great variability in methodology was observed especially regarding sample storage conditions, DNA/RNA extraction, and microbiome characterization. No study clearly considered transfer of the normal placental microbiome to the infant gut. Moreover, some studies in the review and others published subsequently reported little evidence for a placental microbiome in comparison to negative controls. In conclusion, current data are limited and provide no conclusive evidence that there is a normal placental microbiome which has any role in colonization of infant gut.

摘要

鉴于肠道微生物组在健康和疾病中的重要作用，了解建立微生物群落的关键因素（包括婴儿期的肠道定植）至关重要。有人认为，第一次细菌暴露是通过胎盘微生物组。然而，尽管有许多出版物，但胎盘微生物组和细菌从胎盘转移到婴儿肠道的证据的稳健性尚不清楚，因此这个概念存在争议。因此，我们对健康母亲的胎盘、羊水和脐带血微生物组在婴儿肠道定植中的作用的证据进行了系统回顾。大多数经过全面评估的论文都考虑了胎盘组织，但也有一些研究了羊水或脐带血。观察到方法学存在很大差异，特别是在样品储存条件、DNA/RNA 提取和微生物组表征方面。没有研究明确考虑将正常胎盘微生物组转移到婴儿肠道。此外，该综述中的一些研究和随后发表的其他研究报告与阴性对照相比几乎没有胎盘微生物组的证据。总之，目前的数据有限，没有提供确凿的证据表明正常的胎盘微生物组在婴儿肠道定植中发挥任何作用。