Candida albicans gene expression during intra-abdominal infections

描述(申请人提供)：侵袭性念珠菌病(IC)是美国医院最常见的真菌感染，死亡率高达40%。血流感染(念珠菌血症)被普遍认为是最重要的IC类型。腹内念珠菌病(IAC)和其他非血流IC的研究较少。IAC包括两个实体：腹膜炎(腹膜感染)和脓肿(从健康组织中隔离出来的念珠菌和脓液)。最近的论文和我们中心的数据表明，IAC至少和念珠菌血症一样常见，死亡率也差不多。然而，这两种疾病在重要方面有所不同。念珠菌血症最常见的进入途径是从胃肠道(GI)腔经粘膜进入血管系统或直接从血管导管进入。另一方面，IAC是在将假丝酵母菌作为腹膜并发症引入正常无菌腹膜腔后进行的。 透析或更常见的原因是胃肠道渗漏或穿孔。在后一种情况下，假丝酵母菌与粪便物质混合，在大多数情况下，还与肠杆菌等胃肠道细菌混合。白色念珠菌仍然是IAC最常见的原因，而非C。目前，白色念珠菌在念珠菌血症中占主导地位。白念珠菌引起IAC的细胞和分子机制尚不清楚。我们采用了一种简单且可重复的白色念珠菌IAC小鼠模型，复制了从全身性腹膜炎到局限性腹内脓肿的感染的病理生理学和进展。我们使用纳米串计数法检测145株白色念珠菌基因在腹膜炎期间的表达。此外，我们证明了小鼠模型在区分突变的白色念珠菌菌株的相对毒力方面是敏感的，表明它非常适合于发病机制的研究。这些数据为了解白念珠菌在体内激活的生物过程提供了有价值的见解，并揭示了白念珠菌在IAC过程中的基因表达与DC或OPC有很大不同。最近，我们进行了RNA-Seq(DNA深度测序)，以全面确定腹膜炎患者腹腔液中白色念珠菌的基因表达。在这个项目中，我们将检验两个假设：1)白色念珠菌阐述特定阶段 腹膜腔和脓肿中的基因表达谱；2)白念珠菌在IAC过程中受时间和空间调节的基因在发病机制中有明显的贡献。在我们的第一个具体目标中，我们将使用RNA-Seq来测量白念珠菌在小鼠和人类IAC期间的基因表达。在我们的第二个特定目标中，我们将使用我们的小鼠模型来揭示特定的白色念珠菌基因在IAC的发病机制中的作用。除了提供对导致IAC的基因和生物过程的洞察外，该项目还将导致未来对具体发病机制的研究。这项研究将产生关于发病机制的新假说，并有助于为该领域的研究人员选择基因和途径提供信息。此外，这些数据还可以确定开发新的治疗、诊断和疫苗策略的优先目标。

DESCRIPTION (provided by applicant): Invasive candidiasis (IC), the most common fungal infection in U.S. hospitals, is associated with mortality rates as high as 40%. Bloodstream infections (candidemia) are generally accepted as the most important type of IC. Intra-abdominal candidiasis (IAC) and other non-bloodstream IC are less well-studied. IAC encompasses two entities: peritonitis (infection of the peritoneum) and abscesses (collections of Candida and pus that are walled-off from healthy tissue). Data from recent papers and our center indicate that IAC is at least as common as candidemia, and mortality rates are similar. Nevertheless, the diseases differ in important ways. The most common portals of entry for candidemia are translocation from the gastrointestinal (GI) lumen through the mucosa into the vasculature or direct introduction from vascular catheters. IAC, on the other hand, follows the introduction of Candida into the normally sterile peritoneal cavity as a complication of peritoneal dialysis or, more commonly, as a result of GI tract leakage or perforation. In the latter scenarios Candida is admixed with fecal material and, in most cases, GI bacteria such as E. coli. Candida albicans remains the most common cause of IAC, whereas non-C. albicans species are now predominant in candidemia. The cellular and molecular mechanisms by which C. albicans causes IAC are poorly understood. We have adapted a simple and reproducible mouse model of C. albicans IAC that replicates the pathophysiology and progression of infection from generalized peritonitis to localized intra-abdominal abscesses. We used nanoString nCounter assays to measure expression of 145 C. albicans genes during peritonitis. Moreover, we demonstrated that the mouse model is sensitive at distinguishing the relative virulence of mutant C. albicans strains, indicating that it is well-suited to studies of pathogenesis. These data provided valuable insights into biologic processes that are activated by C. albicans in vivo, and revealed that C. albicans gene expression during IAC differs substantially from DC or OPC. More recently, we have performed RNA-Seq (deep sequencing of cDNA) to comprehensively define C. albicans gene expression within peritoneal fluid recovered from a patient with peritonitis. In this project, we will test two hypotheses: 1) C. albicans elaborates stage-specific gene expression profiles within the peritoneal cavity and abscesses; and 2) C. albicans genes that are temporal-spatially regulated during IAC make distinct contributions to pathogenesis. In our first specific aim, we will use RNA-Seq to measure C. albicans gene expression during IAC in mice and humans. In our second specific aim, we will use our mouse model to implicate specific C. albicans genes in the pathogenesis of IAC. In addition to providing insights into genes and biologic processes that contribute to IAC, the project will lead to future studies of specific mechanisms of pathogenesis. This study will generate new hypotheses about pathogenesis, and help inform choices of genes and pathways that can be pursued by investigators in the field. In addition, the data may identify priority targets for the developmentof novel therapeutic, diagnostic and vaccine strategies.