Systematic Genetic Analysis of C. albicans CNS Infection

项目总结 中枢神经系统(CNS)是几乎所有人类主要真菌的重要靶器官 病原菌包括隐球菌、球孢子虫、念珠菌、曲霉菌、组织胞浆菌等。几乎在所有方面 例如，真菌要么定植或感染一个器官系统，然后传播到中枢神经系统。这个 最常见的初始感染部位是肺部，隐球菌的发病机制就是一个例子。 组织胞浆菌、球孢子虫和曲霉菌，而白色念珠菌的独特之处在于它是 在侵袭性疾病期间感染大脑的人类胃肠道。早产儿很早就被认为是 作为白念珠菌中枢神经系统疾病风险最高的患者，尽管最近已经认识到 具有CARD9先天免疫途径突变的成年人也处于高危状态。重要的是，白色念珠菌 脑膜脑炎导致的一个事实是，在败血症中存活下来的婴儿中，感染C. 与感染细菌的婴儿相比，白念珠菌的神经发育结果要差得多。因此，CNS 疾病是念珠菌病的重要临床后遗症。然而，我们对这种机制知之甚少。 这是白念珠菌感染中枢神经系统的能力的基础。为了解决这一知识差距，我们建议 利用一种新的白念珠菌中枢感染模型筛选转录因子和蛋白质集合 蛋白激酶(PK)突变体以确定白念珠菌嗜神经性的关键调节因子。我们发现老鼠缺乏 白介素1受体(IL1-R)在播散性念珠菌病相关脑部负荷显著增加 到同源的WT小鼠。IL1R-/-小鼠中枢神经系统真菌负荷的增加提供了足够强大的动力 允许识别中枢神经系统感染性降低的白色念珠菌突变株的范围，而标准WT 白念珠菌只会在相对较低的真菌负荷下短暂感染小鼠。因此，我们， 建议使用这一新的模型进行基因筛查，以确定C。 白念珠菌中枢神经系统传染性(目标1)。我们将生成Tf突变体条形码库的竞争适应度简档 从静脉(IV)和颅内(IC)接种途径后的小鼠脑组织中分离出。在目标2中， 我们将通过以下方式描述一组集中的Tf和PK突变体的影响：1)分析它们与 对脑血管内皮细胞的影响；2)确定它们对毒力和环境转录的影响 中枢神经系统感染过程中体内的反应基因；以及3)确定它们与 其他TF和PK。这些实验将提供基因和转录的第一个特征 对白念珠菌中枢神经系统感染的要求，并将为未来对C。 白念珠菌的嗜神经性。

PROJECT SUMMARY The central nervous system (CNS) is an important target organ for nearly every major human fungal pathogen including Cryptococcus, Coccidioides, Candida, Aspergillus, Histoplasma and others. In almost all examples, the fungus either colonizes or infects one organ system and then disseminates to the CNS. The most common initial site of infection is the lung as exemplified by the pathogenesis of Cryptococcus, Histoplasma, Coccidioides, and Aspergillus while Candida albicans is unique in that it is a commensal of the human GI tract that infects in the brain during invasive disease. Premature infants have long been recognized as the patient cohort most at-risk for C. albicans CNS disease, although recently it has been recognized that adults with mutations in the CARD9 innate immune pathway are also at high risk. Importantly, C. albicans meningoencephalitis contributes to the fact that, among infants who survive sepsis, those infected with C. albicans have much poorer neurodevelopmental outcomes than infants infected with bacteria. Thus, CNS disease is a clinically important sequelae of candidiasis. However, we know very little about the mechanisms that underlie the ability of C. albicans to infect the CNS. To address this gap in knowledge, we propose to utilize a new model of C. albicans CNS infection to screen collections of transcription factor (TF) and protein kinase (PK) mutants to identify key regulators of C. albicans neurotropism. We discovered that mice lacking the IL-1 receptor (IL1-R) develop dramatically increased brain burden during disseminated candidiasis relative to congenic WT mice. The increased CNS fungal burden in il1r-/- mice provides sufficiently robust dynamic range to allow the identification of C. albicans mutants with decreased CNS infectivity whereas standard WT mouse strains are only transiently infected by C. albicans at relatively low fungal burden. We, therefore, propose to use this novel model to perform a genetic screen to identify TFs and PKs that are required for C. albicans CNS infectivity (Aim 1). We will generate competitive fitness profiles of barcoded pools of TF mutants isolated from mouse brain tissue after both intravenous (IV) and intracranial (IC) inoculation routes. In Aim 2, we will characterize the effects of a focused set of TF and PK mutants by: 1) analyzing their interactions with on brain endothelial cells; 2) determining their effect on the transcription of virulence and environmentally responsive genes in vivo during CNS infection; and 3) determining their genetic interaction profiles with the other TFs and PKs. These experiments will provide the first characterization of the genetic and transcriptional requirements for C. albicans CNS infection and will set the stage for future, detailed mechanistic studies of C. albicans neurotropism.