Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynaecology, Erasmus University Medical Centre, Rotterdam, The Netherlands.
Centre for Reproductive Medicine, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Laarbeeklaan 101-1090, Brussels, Belgium.
Hum Reprod Update. 2019 May 1;25(3):298-325. doi: 10.1093/humupd/dmy048.
The existence of an extensive microbiome in and on the human body has increasingly dominated the scientific literature during the last decade. A shift from culture-dependent to culture-independent identification of microbes has occurred since the emergence of next-generation sequencing (NGS) techniques, whole genome shotgun and metagenomic sequencing. These sequencing analyses have revealed the presence of a rich diversity of microbes in most exposed surfaces of the human body, such as throughout the reproductive tract. The results of microbiota analyses are influenced by the technical specifications of the applied methods of analyses. Therefore, it is difficult to correctly compare and interpret the results of different studies of the same anatomical niche.
The aim of this narrative review is to provide an overview of the currently used techniques and the reported microbiota compositions in the different anatomical parts of the female and male reproductive tracts since the introduction of NGS in 2005. This is crucial to understand and determine the interactions and roles of the different microbes necessary for successful reproduction.
A search in Embase, Medline Ovid, Web of science, Cochrane and Google scholar was conducted. The search was limited to English language and studies published between January 2005 and April 2018. Included articles needed to be original microbiome research related to the reproductive tracts.
The review provides an extensive up-to-date overview of current microbiome research in the field of human reproductive medicine. The possibility of drawing general conclusions is limited due to diversity in the execution of analytical steps in microbiome research, such as local protocols, sampling methods, primers used, sequencing techniques and bioinformatic pipelines, making it difficult to compare and interpret results of the available studies. Although some microbiota are associated with reproductive success and a good pregnancy outcome, it is still unknown whether a causal link exists. More research is needed to further explore the possible clinical implications and therapeutic interventions.
For the field of reproductive medicine, determination of what is a favourable reproductive tract microbiome will provide insight into the mechanisms of both unsuccessful and successful human reproduction. To increase pregnancy chances with live birth and to reduce reproduction-related health costs, future research could focus on postponing treatment or conception in case of the presence of unfavourable microbiota and on the development of therapeutic interventions, such as microbial therapeutics and lifestyle adaptations.
在过去十年中，人体内外广泛存在的微生物组在科学文献中占据了越来越重要的地位。自从下一代测序（NGS）技术、全基因组鸟枪法和宏基因组测序出现以来，已经从依赖培养的微生物鉴定方法转变为不依赖培养的鉴定方法。这些测序分析揭示了人体大多数暴露表面（如生殖道）中微生物的丰富多样性。微生物组分析的结果受到所应用分析方法技术规格的影响。因此，很难正确比较和解释同一解剖部位的不同研究的结果。
本综述的目的是提供一个概述，介绍自 2005 年 NGS 引入以来，不同解剖部位女性和男性生殖道中目前使用的技术和报道的微生物组组成。这对于理解和确定成功繁殖所需的不同微生物的相互作用和作用至关重要。
在 Embase、Medline Ovid、Web of science、Cochrane 和 Google scholar 进行了搜索。搜索仅限于英语语言和 2005 年 1 月至 2018 年 4 月期间发表的研究。纳入的文章必须是与生殖道相关的原始微生物组研究。
本综述提供了一个广泛的、最新的人类生殖医学领域微生物组研究概述。由于微生物组研究中分析步骤的执行存在多样性，如局部方案、采样方法、使用的引物、测序技术和生物信息学管道，使得难以比较和解释现有研究的结果，因此很难得出一般性结论。虽然一些微生物群与生殖成功和良好的妊娠结局相关，但仍不清楚是否存在因果关系。需要进一步研究以进一步探索可能的临床意义和治疗干预。
对于生殖医学领域，确定什么样的生殖道微生物组是有利的，将有助于深入了解人类不成功和成功繁殖的机制。为了增加活产妊娠的机会并降低与生殖相关的健康成本，未来的研究可以集中在存在不利微生物群的情况下推迟治疗或受孕，并专注于开发治疗干预措施，如微生物治疗和生活方式调整。
