Mechanisms of Candida auris skin colonization

摘要 金黄色葡萄球菌是一种相对较新的机会性真菌病原体，正以较高的内在致病率在世界范围内传播。 对抗真菌抗生素有抵抗力，对人体皮肤有很强的亲和力。它现在被疾病控制与预防中心列为最高 抗药性真菌威胁。流行病学分析表明，病原体传播在 共享住房环境，如医院或疗养院。重要的是，人与人之间的传播 皮肤相关酵母菌的感染似乎是主要的传播方式。虽然奥里斯的皮肤定植是 有其他危险因素的患者可能会出现无症状、危及生命的疾病，例如 免疫抑制、静脉导管放置、手术和抗生素。对分子的理解 奥里斯顽强地在皮肤上定植的机制可能提供了潜在的机会来中断 感染周期。不幸的是，还没有发现对宿主皮肤定植有重要作用的分子。要开始 为了解决这个问题，我们建立了三种皮肤定植和皮肤表皮化的小鼠模型。 适合调查金黄色念珠菌的白色念珠菌感染。使用这些模型，我们观察到 金黄色葡萄球菌的滴度明显高于白色念珠菌。与白色念珠菌不同，金黄色念珠菌不会引起皮肤损伤或 诱导关键的抗真菌促炎细胞因子IL-17的表达。值得注意的是，C.Auris显示了集群 表皮中的酵母菌以及毛囊的侵入，这两种情况都不是白色念珠菌所见。在一个 对~700株白色念珠菌零突变体进行正向遗传筛查，我们确定了4个皮肤表面所需的基因 皮肤感染。我们使用基于CRISPR/Cas9的协议中断了C.Auris的同源基因。我们发现所有的 4个突变体在金黄地鼠皮肤定植方面存在缺陷。值得注意的是，四个基因中的两个编码金黄色葡萄球菌 猪MAPK信号通路各组成部分的同源基因，是有效皮肤所必需的 在所有三种模式中都是殖民主义。这些数据使我们假设，猪MAPK信号通路 通过控制下游靶基因的表达来控制皮肤在金黄色葡萄球菌中的定植。我们假设 这些靶基因中的一个或多个将参与促进金黄色葡萄球菌有效定植的能力 皮肤。我们将通过1)调查C.Auris Hog1的作用来检验这一高风险/高回报假说 皮肤定植途径及其在基因调控中的作用和2)确定金黄色葡萄球菌的效应因子 皮肤殖民。这些研究有可能确定金黄色葡萄球菌所需的分子和机制。 定植皮肤，这是这种重要的新出现的耐药病原体感染循环的中心方面。 在奠定了基础之后，我们处于实现这些目标的有利地位，我们预计这些目标将 为开始获得对金龟子独特生物学的分子洞察力提供了基础。

ABSTRACT C. auris is a relatively new opportunistic fungal pathogen that is spreading worldwide with high rates of intrinsic resistance to antifungal antibiotics and a strong affinity for human skin. It is now ranked by the CDC as the top drug-resistant fungal threat. Epidemiological analysis suggests that pathogen transmission occurs efficiently in shared housing environments such as hospitals or nursing homes. Importantly, person-to-person transmission of skin-associated yeasts appears to be a primary mode of spread. Although C. auris skin colonization is asymptomatic, life-threatening disease can arise in patients with additional risk factors, such as immunosuppression, intravenous catheter placement, surgery, and antibiotics. Understanding of the molecular mechanisms by which C. auris tenaciously colonizes the skin might offer potential opportunities to interrupt the infection cycle. Unfortunately, no molecules been identified that are important for host skin colonization. To begin to address this problem, we have established three mouse models of skin colonization and epicutaneous infection with Candida albicans that are suitable for investigations of C. auris. Using these models, we observe significantly higher titers of C. auris than C. albicans. Unlike C. albicans, C. auris fails to induce skin damage or to induce expression of the key antifungal pro-inflammatory cytokine, IL-17. Notably, C. auris displays clusters of yeast in the epidermis as well as invasion of the hair follicles, neither of which are seen with C. albicans. In a forward genetic screen of ~700 C. albicans null mutants, we identified four genes required for epicutaneous infection of skin. We disrupted the C. auris orthologs using a CRISPR/Cas9-based protocol. We found that all four mutant displayed defects in skin colonization in C. auris. Notably, two of the four genes encode C. auris orthologs of components of the HOG MAP kinase signaling pathway and are required for effective skin colonization in all three models. These data lead us to hypothesize that the HOG MAPK signaling pathway controls skin colonization in C. auris by controlling the expression of downstream target genes. We hypothesize that one or more of these target genes will be involved in promoting the ability of C. auris to effectively colonize the skin. We will test this high-risk/high-payoff hypothesis by 1) Investigating the role of the C. auris Hog1 pathway in skin colonization and establishing its role in gene regulation and 2) Identifying effectors of C. auris skin colonization. These studies have the potential to identify molecules and mechanisms required for C. auris to colonize the skin, a central aspect of the infection cycle of this important emerging drug-resistant pathogen. Having laid the groundwork, we are in a strong position to accomplish these goals, which we anticipate will provide a foundation to begin to obtain molecular insights into the unique biology of C. auris.