Longitudinal Study of the Vaginal Microbiome Prior To Incident STI

 描述（由申请人提供）：美国每年约有2000万新发性传播感染（STI），为医疗保健系统增加了160亿美元的医疗费用。一种尚未充分探索的预防女性性传播感染的方法是利用阴道微生物组的保护功能。阴道微生物群在防止病原体定植方面发挥重要作用。阴道乳杆菌属提供广谱抗微生物活性部分是通过它们产生乳酸， 这就产生了一个对病原体有害的酸性环境。迄今为止，只有基于细菌培养技术或显微镜评价的研究可用于描述阴道细菌与STI风险之间的时间关联。然而，大多数微生物物种（>90%）抵抗培养，并且显微镜仅提供形态学信息。阴道微生物群的完整表征需要我们提出的分子方法。我们已经使用宏基因组分析表明，乳杆菌属的特定基因型。与衣原体感染和阴道微生物群不稳定有关。我们提出了一个新的假设，即除了低乳酸菌状态外，特定的乳酸菌基因型与STI风险增加相关，并且由乳酸菌产生的D-和L-乳酸异构体的混合物。对性传播感染风险有不同影响。炎症可能导致阴道上皮细胞的破坏，使病原体进入更深的组织，因此，我们还假设与特定阴道微生物群相关的局部免疫反应可能促进STI。我们试图利用从1999年NIH阴道植物群纵向研究中收集的存档宫颈阴道灌洗（CVL）样本，该研究对3,620名妇女进行了为期一年的随访，每季度进行一次评估。共有681名妇女被观察到获得沙眼衣原体（CT），淋病奈瑟菌（GC），或阴道毛滴虫（TV）生殖器感染的事件。储存库样本提供了一个独特的机会，在一项有效性良好的研究中，在获得STI之前表征阴道微生物组。我们将采用发病密度抽样进行巢式病例对照研究。病例将被定义为发生性传播感染的女性，我们将在首次性传播感染检测之前的访视中分析样本。对照组将在年龄、种族和访视次数上与病例匹配，并且将是在病例访视时未发生STI的女性。具体目的是：（1）使用16 S rRNA基因分析评估阴道微生物群与CT、GC和TV生殖器感染发病率之间的关联;（2）比较病例和对照组中D-和L-乳酸异构体的水平;（3）调查是否存在特定的乳酸杆菌菌株，使用宏基因组分析，确定宫颈阴道免疫应答是否独立地预测发生性STI。所有四个目标都将在综合行为数据的背景下进行建模。这项研究将提供对阴道微生物组在性传播感染保护中作用的功能性理解，并可能揭示预防性传播感染和改善女性健康的新目标。

 DESCRIPTION (provided by applicant): There are approximately 20 million new sexually transmitted infections (STIs) in the U.S. each year that add $16 billion in medical costs to the healthcare system. One approach to prevention of STIs in women that has not been fully explored is harnessing the protective features of the vaginal microbiome. The vaginal microbiota play an important role in preventing colonization by pathogenic organisms. Vaginal Lactobacillus spp. provide broad-spectrum antimicrobial activity in part through their production of lactic acid, which creates an acidic and hostile environment to pathogens. To date, only studies based on bacterial cultivation techniques or microscopic evaluation are available to describe the temporal association between the vaginal bacteria and risk of STI. However, a majority of microbial species (>90%) resist cultivation and microscopy only provides morphological information. Complete characterization of the vaginal microbiota requires molecular approaches as we propose. We have shown using metagenomic analysis that specific genotypes of Lactobacillus spp. are associated with both chlamydial infection and vaginal microbiota instability. We are putting forth a novel hypothesis that, in addition to a low-Lactobacillus state, specific Lactobacillus genotypes are associated with increased risk for STIs, and that the mixture of D- and L- lactate isomers produced by Lactobacillus spp. differentially affects STI risk. Inflammation may cause destruction of the vaginal epithelium, allowing pathogens to access deeper tissues, and therefore, we also hypothesize that local immune responses associated with specific vaginal microbiota may facilitate STIs. We seek to utilize archived cervicovaginal lavage (CVL) samples collected from the 1999 NIH Longitudinal Study of Vaginal Flora in which 3,620 women were followed for one year with quarterly assessments. A total of 681 women were observed to acquire an incident Chlamydia trachomatis (CT), Neisseria gonorrhea (GC), or Trichomonas vaginalis (TV) genital infection. The repository samples provide a unique opportunity to characterize the vaginal microbiome prior to acquisition of STIs in a well-powered study. We will conduct a nested case-control study with incidence density sampling. Cases will be defined as women who had an incident STI and we will analyze the sample at the visit prior to the first STI detection. Controls will be matched on age, ethnicity and visit number to cases and will be women who did not develop a STI by the time of the case visit. Specific aims are to (1) Evaluate the association between vaginal microbiota and incidence of CT, GC, and TV genital infection using 16S rRNA gene analysis; (2) Compare levels of D- and L-lactic acid isomers in cases and controls; (3) Investigate if specific strains of Lactobacillus (or other bacterium) are associated with STI risk using metagenomic analysis; (4) Determine if cervicovaginal immune responses independently predict incident STIs. All four aims will be modeled in the context of comprehensive behavioral data. This study will provide a functional understanding of the vaginal microbiome's role in STI protection and may reveal novel targets to prevent STIs and improve women's health.