The Cryptococcus neoformans Titan cell is an inducible and regulated morphotype underlying pathogenesis
The Cryptococcus neoformans Titan cell is an inducible and regulated morphotype underlying pathogenesis
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DOI：
10.1101/190587
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发表时间：
2017-09
期刊：
影响因子：
6.7
通讯作者：
I. Dambuza;Thomas A. Drake;A. Chapuis;L. Taylor-Smith;Nathalie M. Legrave;T. Rasmussen;M. Fisher;T. Bicanic;T. Harrison;M. Jaspars;R. May;Gordon D. Brown;R. Yuecel;D. MacCallum;Elizabeth R. Ballou
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作者：
I. Dambuza;Thomas A. Drake;A. Chapuis;L. Taylor-Smith;Nathalie M. Legrave;T. Rasmussen;M. Fisher;T. Bicanic;T. Harrison;M. Jaspars;R. May;Gordon D. Brown;R. Yuecel;D. MacCallum;Elizabeth R. Ballou
真菌经历细胞形状的变化，以响应驱动发病机制和生态位适应的环境刺激，如双态真菌响应温度变化的酵母到菌丝的转变。新型隐球菌在宿主肺中经历了一个不寻常的形态发生转变，从单倍体酵母到大的、高度多倍体的细胞，称为泰坦细胞。泰坦细胞影响真菌与宿主细胞的相互作用，包括通过增加耐药性，改变细胞大小和改变病原体相关分子模式暴露。尽管这些细胞在发病机制中发挥着重要作用，但由于缺乏可重复的体外诱导系统，因此无法理解驱动形态转变的环境刺激以及其独特生物学的分子机制。在这里，我们证明了可重复的体外泰坦细胞诱导响应于与宿主肺一致的环境刺激。体外Titan细胞表现出体内产生的Titan细胞的所有特性，当前的金标准，包括改变的包膜、细胞壁、大小、高母细胞倍性和非整倍体后代。我们确定细菌肽聚糖作为血清化合物与细胞大小和倍性的转变，并证明支气管灌洗液和大肠杆菌的能力。coli共培养以诱导钛化。此外，我们证明了我们的检测方法能够在体外鉴定已建立和以前未描述的钛化调节剂，并研究临床分离株的钛化能力及其对疾病结局的影响。总之，这些发现为酵母到泰坦转变的环境刺激和分子机制提供了新的见解，并为未来表征这种重要形态型建立了必要的体外模型。细胞形状的变化通过允许免疫逃避和传播而成为真菌发病机制的基础。曲霉菌和白色念珠菌菌丝驱动组织渗透。荚膜组织胞浆菌和C.白色酵母菌的生长允许逃逸和传播。作为主要的毒力决定因素，形态发生转变在动物模型和体外被广泛研究。致病真菌新型隐球菌是一种芽殖酵母，在宿主肺中转变为一种称为泰坦细胞的不寻常形态。泰坦巨人体型巨大，是多倍体，细胞壁和荚膜发生了变化，并产生了单倍体的后代。它们的大小阻止吞噬细胞的吞噬，但它们与传播和改变免疫反应有关。尽管它们对疾病有重要影响，但在体外复制酵母到泰坦的开关已被证明具有挑战性。在这里，我们表明，泰坦引起的主机相关的刺激，包括血清和支气管肺泡灌洗液。我们确定细菌肽聚糖作为相关的诱导化合物，并预测在体内泰坦缺陷的临床分离。调控体内钛化的基因也影响体外形成。钛化作用是一种保守的跨C. neoformans物种复合体。总之，我们表明，泰坦细胞是一个受管制的形态类似于酵母菌到菌丝的过渡，并建立新的方法来研究泰坦以外的宿主肺。
Fungi undergo changes in cell shape in response to environmental stimuli that drive pathogenesis and niche adaptation, such as the yeast-to-hyphal transition of dimorphic fungi in response to changing temperature. The basidiomycete Cryptococcus neoformans undergoes an unusual morphogenetic transition in the host lung from haploid yeast to large, highly polyploid cells termed Titan cells. Titan cells influence fungal interaction with host cells, including through increased drug resistance, altered cell size, and altered Pathogen Associated Molecular Pattern exposure. Despite the important role these cells play in pathogenesis, understanding the environmental stimuli that drive the morphological transition, and the molecular mechanisms underlying their unique biology, has been hampered by the lack of a reproducible in vitro induction system. Here we demonstrate reproducible in vitro Titan cell induction in response to environmental stimuli consistent with the host lung. In vitro Titan cells exhibit all the properties of in vivo generated Titan cells, the current gold standard, including altered capsule, cell wall, size, high mother cell ploidy, and aneuploid progeny. We identify bacterial peptidoglycan as a serum compound associated with shift in cell size and ploidy, and demonstrate the capacity of bronchial lavage fluid and E. coli co-culture to induce Titanisation. Additionally, we demonstrate the capacity of our assay to identify established and previously undescribed regulators of Titanisation in vitro and investigate the Titanisation capacity of clinical isolates and their impact on disease outcome. Together, these findings provide new insight into the environmental stimuli and molecular mechanisms underlying the yeast-to-titan transition and establish an essential in vitro model for the future characterization of this important morphotype. Author Summary Changes in cell shape underlie fungal pathogenesis by allowing immune evasion and dissemination. Aspergillus and Candida albicans hyphae drive tissue penetration. Histoplasma capsulatum and C. albicans yeast growth allows evasion and dissemination. As major virulence determinates, morphogenic transitions are extensively studied in animal models and in vitro. The pathogenic fungus Cryptococcus neoformans is a budding yeast that, in the host lung, switches to an unusual morphotype termed the Titan cell. Titans are large, polyploid, have altered cell wall and capsule, and produce haploid daughters. Their size prevents engulfment by phagocytes, yet they are linked to dissemination and altered immune response. Despite their important influence on disease, replicating the yeast-to-Titan switch in vitro has proved challenging. Here we show that Titans are induced by host-relevant stimuli, including serum and bronchio-alveolar lavage fluid. We identify bacterial peptidoglycan as a relevant inducing compound and predict an in vivo Titan defect for a clinical isolate. Genes regulating in vivo Titanisation also influence in vitro formation. Titanisation is a conserved morphogenic switch across the C. neoformans species complex. Together, we show that Titan cells are a regulated morphotype analogous to the yeast-to-hyphal transition and establish new ways to study Titans outside the host lung.