Consequences of vaginal microbiota on IFNγ-mediated clearance of Chlamydia trachomatis

沙眼衣原体（CT）感染是一个主要的公共卫生问题，因为它们可以产生不利影响， 女性生育力和新生儿健康。虽然自然史研究表明，一些妇女自发清除， 它们的感染，允许CT自发清除的生理条件仍然难以捉摸。理解 后者是开发有效预防CT感染及其破坏性后果的疫苗的关键。 体外和体内研究表明，干扰素γ（IFNγ）是抗CT的主要保护性细胞因子。 IFNγ诱导宿主酶吲哚胺2，3-双加氧酶（IDO 1）降解色氨酸，这是一种必需的代谢酶。 CT的氨基酸，其不能从头合成色氨酸。所有临床生殖器CT分离株都进化为 逃避IFNγ作用的机制，特别是它们可以表达功能性色氨酸合酶， 回收外源提供的吲哚，在细胞内衣原体内含物中产生色氨酸， 它不受IDO 1影响。虽然CT和人体细胞都不合成吲哚，但阴道上皮细胞的一些成员 细菌性阴道病（BV）期间数量和比例大幅增加的微生物组可以这样做。因此我们 假设阴道微生物组的组成及其提供吲哚的能力调节了 IFNγ依赖性宿主免疫对CT的效力。我们现有的临床数据支持这一假设; 尽管所有自发清除CT感染的妇女宫颈内IFNγ水平较高， 未能清除感染的妇女。我们建议使用一个高风险的队列来严格检验这一假设。 非裔美国妇女参加我们在新奥尔良的性病诊所。队列将被分层， 自发清除CT感染（在我们的队列中约28%）或在入组和 复诊治疗。通过关注自发清除感染的妇女， 我们将研究在达到宫颈内IFNγ水平阈值的清洁妇女中， 以下目的：1）确定感染微环境（色氨酸/吲哚/IFNγ/CT负荷和基因表达 2）确定流行的阴道微生物组的差异，及其吲哚- 在清除者和非清除者之间的产生能力;和3）使用新的子宫颈内上皮细胞模型， 直接测试产生吲哚的微生物组成员限制IFNγ介导的CT清除的能力，以及 评价已知的小分子吲哚生物合成抑制剂增强IFNγ介导的CT的功效 在合并感染期间清除。拟议研究的结果将提供重要信息 需要设计新的免疫学和药理学方法，以改善CT的临床结果， 感染的病人。对自发清除过程中使用的机制进行建模，将定义协同清除的影响。 感染对宿主对CT感染的反应的效力。这将大大改善患者的健康状况， 鉴于生殖器CT感染造成的巨大的人力和财力损失，

Chlamydia trachomatis (CT) infections are a major public health concern as they can adversely affect female fertility and neonatal health. While natural history studies indicate that some women spontaneously clear their infection, the physiological conditions that permit spontaneous clearance of CT remain elusive. Understand the latter is key to developing an effective vaccine that to prevent CT infection and its devastating consequences. In vitro and in vivo studies indicate that interferon gamma (IFNγ) is the primary protective cytokine against CT. IFNγ induces the host enzyme indoleamine 2,3-dioxygenase (IDO1) that degrades tryptophan, an essential amino acid for CT, which cannot synthesize tryptophan de novo. All clinical genital CT isolates have evolved a mechanism to evade the effect of IFNγ, specifically they can express a functional tryptophan synthase that salvages exogenously provided indole to generate tryptophan within the intracellular chlamydial inclusion where it is impervious to IDO1. While neither CT, nor human cells, synthesize indole, some members of the vaginal microbiome that increase greatly in number and proportion during bacterial vaginosis (BV), can do so. Thus, we hypothesize that the composition of the vaginal microbiome, and its capacity to provide indole, modulates the efficacy of IFNγ-dependent host immunity against CT. This hypothesis is supported by our existing clinical data; although all women who spontaneously cleared CT infection had high endocervical IFNγ levels, so did ~40% of women who failed to clear infection. We propose to rigorously test this hypothesis using a cohort of high-risk African-American women attending our STD clinic in New Orleans. The cohort will be stratified into groups that spontaneously clear CT infections (~28% in our cohort) or fail to clear CT infection between enrollment and return-for-treatment visits. By focusing on women who spontaneously clear infection, and the ~40% of non- clearing women who meet the threshold endocervical IFNγ levels observed in clearers, we will investigate the following objectives: 1) Determine the infection micromilieu (tryptophan/indole/IFNγ/CT load & gene expression profile) correlates of clearance; 2) Determine differences in the prevalent vaginal microbiome, and its indole- generation capacity, between clearers and non-clearers; and 3) Using a novel endocervical epithelial cell model, directly test the capacity of indole-producing microbiome members to limit IFNγ-mediated CT clearance, and evaluate the efficacy of known small molecule indole biosynthesis inhibitors to augment IFNγ-mediated CT clearance during co-infections. The outcomes from the proposed studies will provide essential information needed to design novel immunological and pharmacological approaches that improve clinical outcomes for CT- infected patients. Modeling the mechanisms used during spontaneous clearance will define the effects of co- infection on the efficacy of the host response to CT-infection. This will significantly improve patient health and welfare in light of the tremendous human and financial toll that is imposed by genital CT infections.