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，因为它们会对 女性生育力和新生儿健康。虽然自然历史研究表明，一些女性自发地明确 他们的感染，允许CT自发清除的生理条件仍然难以捉摸。了解 后者是开发有效疫苗的关键，该疫苗可以预防CT感染及其破坏性后果。 体内外研究表明，干扰素γ是抗CT的主要保护性细胞因子。 干扰素γ诱导宿主酶吲哚胺2，3-双加氧酶(IDO_1)降解色氨酸，色氨酸是一种必需的 CT的氨基酸，不能从头合成色氨酸。所有临床生殖器CT分离株都进化为 机制来逃避干扰素γ的作用，特别是它们可以表达一种功能性的色氨酸合成酶， 回收物外源提供吲哚以在细胞内衣原体包涵体内产生色氨酸，其中 它不受IDO1的影响。虽然CT和人类细胞都不能合成吲哚，但阴道的一些成员 在细菌性阴道病(BV)期间数量和比例大幅增加的微生物群可以做到这一点。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 干扰素γ依赖宿主免疫治疗沙眼衣原体的疗效观察这一假设得到了我们现有临床数据的支持； 尽管所有自发清除CT感染的女性宫颈内干扰素γ水平都很高，但约40%的女性也是如此 未能清除感染的女性。我们建议使用一组高风险人群来严格检验这一假设。 来我们新奥尔良性病诊所就诊的非裔美国女性。该队列将被分成不同的组， 自发清除CT感染(在我们的队列中约28%)或未能在登记和注册之间清除CT感染 返乡治疗探视。通过关注自发清除感染的女性，以及~40%的非 清除达到清理员宫颈内干扰素γ水平门槛的妇女，我们将调查 目标：1)测定感染微环境(色氨酸/吲哚/干扰素γ/CT载量及基因表达 轮廓)清除性的相关性；2)确定流行的阴道微生物组及其吲哚的差异。 在清理者和非清理者之间的生成能力；以及3)使用新的宫颈内皮细胞模型， 直接测试产生吲哚的微生物组成员限制干扰素γ介导的CT清除的能力，以及 评价已知小分子吲哚生物合成抑制剂增强干扰素γ介导的CT的效果 在合并感染期间清除。拟议研究的结果将提供重要的信息。 需要设计新的免疫学和药理学方法来改善CT的临床结果- 被感染的病人。对自发清除过程中使用的机制进行建模将确定CO- 感染对宿主对沙眼衣原体感染反应的影响。这将显著改善患者的健康和 鉴于生殖器沙眼衣原体感染造成巨大的人力和经济损失，联合国儿童基金会将继续致力于提供福利。

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.