Impact of periconceptual vaginal microbiota on women's risk of preterm birth

 描述（由申请人提供）：估计10%的妊娠发生早产，导致婴儿发病率和死亡率高。这一公共卫生问题导致了一些国内和国际举措，包括美国卫生部长关于预防早产和千年发展目标（目标4，降低儿童死亡率）的会议。自发性早产（SPTB）占早产的70-80%，其余为药物诱导。细菌性阴道病（BV）是一种常见的疾病，一直与SPTB有关。许多与BV相关的细菌仍然难以使用培养方法检测，但使用分子方法很容易检测到。尽管BV和SPTB之间存在一致的相关性，但在许多临床试验中，妊娠期间治疗BV未能减少SPTB，这提出了关键问题：关键细菌物种是否介导SPTB的风险？妊娠期间BV治疗是否太晚而无法减少SPTB？我们的多学科团队一直处于开发尖端实验室技术的最前沿，并将其应用于精心进行的流行病学研究，以取得将阴道微生物群破坏与不良生殖健康结果联系起来的重要发现。在这项提案中，我们将测试总体假设，即在受孕时存在的高风险阴道细菌物种在子宫腔定植，引起亚临床炎症，并导致SPTB。我们将利用获得设施，训练有素的工作人员和肯尼亚妇女参加由美国CDC和NIH资助的孕前诊所，使这项独特的病例队列研究成为可能。目的1将采用广谱16 S核糖体RNA基因聚合酶链反应（PCR）和深度测序来比较SPTB与足月分娩女性的阴道细菌群落结构、多样性、丰富性和受孕期附近关键物种的存在。目标2将使用高灵敏度定量PCR（qPCR）检测来比较SPTB女性与足月分娩女性在受孕前后关键阴道细菌种类的存在和浓度，验证或反驳目标1中观察到的初步关联。目的3将利用分娩时收集的胎膜和脐带样品，结合物种特异性qPCR测定和组织学检查，以确定目的1和2中与SPTB相关的阴道细菌是否上升到上生殖道并引起炎症。与此同时，我们将研究怀孕期间关键阴道细菌物种与SPTB之间的关联，使我们能够直接比较与围怀孕期与怀孕期间确定的阴道细菌相关的SPTB风险。确定接近受孕时间和SPTB的细菌物种和群落之间的密切关系，有望改变我们理解阴道微生物群如何影响女性SPTB风险的范式。这些数据可以为制定有针对性的干预措施提供信息，这些干预措施的基础是消除高风险物种，并在计划怀孕的妇女中促进低风险阴道细菌群落，特别是在先前的SPTB之后。

 DESCRIPTION (provided by applicant): Preterm birth occurs in an estimated 10% of pregnancies, causing high rates of morbidity and mortality in infants. This public health problem has led to domestic and international initiatives including the US Surgeon General's Conference on Preventing Preterm Birth and the Millennium Development Goals (Goal 4, Reduce Child Mortality). Spontaneous preterm birth (SPTB) accounts for 70-80% of preterm births, with the remainder being medically induced. Bacterial vaginosis (BV) is a common condition that has consistently been associated with SPTB. Many bacteria associated with BV remain difficult to detect using cultivation methods, but are easily detected using molecular methods. Despite the consistent association between BV and SPTB, treating BV during pregnancy has failed to reduce SPTB in numerous clinical trials, raising critical questions: Do key bacterial species mediate the risk of SPTB? Is treatment of BV during pregnancy too late to reduce SPTB? Our multidisciplinary team has been at the forefront in developing cutting-edge laboratory techniques and applying them in carefully conducted epidemiological studies to make important discoveries linking disruption of the vaginal microbiota to adverse reproductive health outcomes. In this proposal, we will test the overarching hypothesis that high-risk vaginal bacterial species present near the time of conception colonize the uterine cavity, causing sub-clinical inflammation, and leading to SPTB. We will leverage access to facilities, highly trained staff, and a population of Kenyan women attending preconception clinics supported with US CDC and NIH funding, to make this unique case-cohort study possible. Aim 1 will employ broad-range 16S ribosomal RNA gene polymerase chain reaction (PCR) and deep sequencing to compare vaginal bacterial community structure, diversity, richness, and the presence of key species near conception, in women with SPTB vs. term delivery. Aim 2 will use highly sensitive quantitative PCR (qPCR) assays to compare the presence and concentrations of key vaginal bacterial species near conception in women with SPTB vs. term birth, validating or refuting preliminary associations observed in Aim 1. Aim 3 will utilize fetal membrane and umbilical cord samples collected at delivery, combining species-specific qPCR assays and histological examination, to determine whether vaginal bacteria associated with SPTB in Aims 1 and 2 ascend to the upper genital tract and cause inflammation. In parallel, we will examine associations between key vaginal bacterial species during pregnancy and SPTB, allowing us to directly compare the risk of SPTB associated with vaginal bacteria identified in the peri-conception period vs. during pregnancy. Identification of strong relationships between bacterial species and communities present close to the time of conception and SPTB is expected to shift our paradigm for understanding how vaginal microbiota influences women's risk of SPTB. These data could inform development of targeted interventions based on elimination of high-risk species and promotion of low-risk vaginal bacterial communities in women planning a pregnancy, particularly after prior SPTB.