Defining human interferon-stimulated genes with novel functions in host defense to Chlamydia infections

摘要 沙眼衣原体是世界上传播最广泛的性传播细菌病原体。 感染沙眼衣原体的人最初通常没有症状，阻碍了正确的诊断和治疗 采取必要的治疗策略来阻止这一“沉默的流行病”。如果没有得到适当的治疗，这些细菌能够 建立一种长期、持续的感染，最终可能导致严重的医学后遗症。这些 并发症主要发生在女性，包括盆腔炎、危及生命的异位 怀孕或不孕。沙眼衣原体微生物致病机制的一个重要组成部分是它能够 逃避免疫检测和人类宿主赋予的其他抗微生物反应。这些主机防御系统 很大程度上是由细胞因子干扰素-γ(干扰素-γ)刺激上皮细胞占据 上调干扰素刺激基因(ISGs)表达的感染部位。这些ISG就是 负责执行和清除入侵微生物的免疫系统。为了颠覆……的效果 干扰素γ并在上皮细胞中成功复制，沙眼衣原体必须进化出对ISGs的抵抗力 通常以其他细菌病原体为目标并加以摧毁。然而，这些ISG的身份和职能， 以及抑制ISG功能的沙眼衣原体毒力效应器，人们对此知之甚少。为了追求 为了回答这些问题，我们进行了两个互补的筛查，以确定i)具有抗衣原体的ISG 活性和ii)沙眼衣原体对干扰素γ治疗敏感的遗传突变体。在这个目标1中 提案，我们将结合人类细胞的功能遗传学和细胞生物学研究来解剖 这些抗衣原体抗体所产生的细胞内反应。在目标2中，我们将结合并行 细菌遗传学和全基因组测序定位致病遗传因素的方法 负责沙眼衣原体逃避干扰素γ介导的免疫。总而言之，这些实验将 人ISGs介导的细胞内源性防御与反转录因子之间的动态关系 感染过程中使用的衣原体耐药机制。这些研究的影响将 为开发新的抗衣原体药物或疫苗接种策略提供重要平台 治疗与之相关的疾病。

ABSTRACT Chlamydia trachomatis is the most widespread sexually transmitted bacterial pathogen in the world. People infected with C. trachomatis are often initially asymptomatic, hindering the proper diagnostic and therapeutic strategies necessary to impede this “silent epidemic”. If not properly treated, the bacteria are able to establish a long-lasting, persistent infection that can ultimately lead to severe medical sequelae. These complications arise predominantly in women, and include pelvic inflammatory disease, life-threatening ectopic pregnancies or infertility. A critical component of the microbial pathogenesis of C. trachomatis is its ability to evade immune detection and other antimicrobial responses conferred by its human host. These host defenses are largely galvanized by the cytokine interferon-gamma (IFNγ), which stimulates epithelial cells occupying the site of an infection to up regulate the expression of interferon-stimulated-genes (ISGs). These ISGs are then responsible for the execution and immune clearance of invading microbes. In order to subvert the effects of IFNγ and successfully replicate in epithelial cells, C. trachomatis must have evolved counterdefenses to ISGs that normally target and destroy other bacterial pathogens. However, the identity and function of these ISGs, as well as the C. trachomatis virulence effectors that inhibit ISG functions, are poorly understood. In pursuit of answering these questions, we performed two complementary screens to identify i) ISGs with anti-Chlamydia activities and ii) C. trachomatis genetic mutants with hypersensitivity to IFNγ treatment. In Aim 1 of this proposal, we will use a combination of functional genetics and cell biological studies in human cells to dissect the intracellular responses conferred by these anti-Chlamydia ISGs. In Aim 2, we will combine parallel approaches in bacterial genetics and whole-genome sequencing to pinpoint the causative genetic elements responsible for C. trachomatis evasion of IFNγ-mediated immunity. Taken together, these experiments will interrogate the dynamic relationship between cell-intrinsic defenses mediated by human ISGs and counter- resistance mechanisms of Chlamydia that are employed during infection. Implications of these studies will provide important platforms for the development of novel anti-Chlamydia medicines or vaccination strategies that treat its associated disease.