A link between mating pheromone sensing and virulence of Cryptococcus neoformans

描述（由申请方提供）：新型隐球菌是一种人类致病真菌，可在免疫功能低下的个体中引起危及生命的脑膜脑炎。隐球菌病的一个重要方面是C。新生儿细胞穿过血脑屏障虽然在过去的几年中已经阐明了中枢神经系统（CNS）渗透的过程，但C。neoformans诱导这些过程是未知的。有趣的是，C。新生儿有两种交配型（A和A）;然而，绝大多数临床分离株是交配型。虽然在最常见的致病性隐球菌中，在a和a菌株同时共感染期间，在与同类菌株的个体感染中没有观察到毒力差异，但a细胞在CNS中占主导地位。通过比较单个和合并感染中的a和a细胞，我们有机会鉴定进入CNS所需的特异性毒力因子。因为C. neoformans细胞使用信息素感知并响应相反交配伙伴的细胞，在初步实验中，我们破坏了A和A细胞中的信息素感知，并发现A细胞被信息素信号传导抑制进入大脑。我们假设信息素信号在C.这种信息素信号传导的下游靶点影响C.有血脑屏障的新生儿我们建议测试这些假设，扰动在体内信息素信号，使用突变株改变信息素传感或信息素生产。这些突变株的毒力将在个体和合并感染中进行检查，并用于通过微阵列分析来帮助识别这种信息素信号传导的下游靶标。这些信息将被用于检查影响CNS进入的细胞特征的变化。此外，在感染过程中将检查信息素水平，以确定何时信息素信号可能对毒力潜力很重要。这些研究将允许鉴定隐球菌CNS渗透的关键组分，并为旨在减少CNS渗透以减轻疾病症状并允许增加抗真菌药物暴露的治疗策略提供基础。

DESCRIPTION (provided by applicant): Cryptococcus neoformans is a human pathogenic fungus that causes life-threatening meningoencephalitis in immunocompromised individuals. One important aspect of cryptococcosis is the ability of C. neoformans cells to cross the blood-brain barrier. While the processes involved in central nervous system (CNS) penetration have been elucidated over the past few years, the methods by which C. neoformans induces these processes are unknown. Interestingly, C. neoformans has two mating types (a and a); however the vast majority of clinical isolates are a mating type. While no differences in virulence are observed in individual infections with congenic strains in the most commonly pathogenic variety of Cryptococcus during coinfection of a and a strains simultaneously, the a cells predominate in the CNS. By comparing the a and a cells in individual and coinfections we have the opportunity to identify virulence factors specifically required for entry into the CNS. Because C. neoformans cells sense and respond to cells of the opposite mating partner using pheromones, in preliminary experiments we disrupted pheromone sensing in both a and a cells and discovered that a cells are inhibited from entering the brain by pheromone signaling. We hypothesize that pheromone signaling plays a central role in C. neoformans entry into the CNS and that the downstream targets of this pheromone signaling affect the interaction of C. neoformans with the blood-brain barrier. We propose to test these hypotheses by perturbing in vivo pheromone signaling using mutant strains altered in either pheromone sensing or pheromone production. The virulence of these mutant strains will be examined in individual and coinfections and used to help identify the downstream targets of this pheromone signaling by microarray analysis. This information will then be used to examine changes in cellular traits that affect CNS entry. Furthermore, pheromone levels will be examined during the infectious process to define when pheromone signaling is likely to be important for virulence potential. These studies will allow the identification of key components of CNS penetration by Cryptococcus and provide a foundation for treatment strategies designed to reduce CNS penetration to alleviate disease symptoms and allow for increased exposure to antifungal drugs.