New methods for the early diagnosis of invasive fungal infections

描述（由申请人提供）：侵袭性真菌感染，如隐球菌病，念珠菌病和曲霉病，在过去二十年中急剧出现，预后非常差。尽管在改进分子和遗传工具以研究其发展和进展方面取得了重大进展，但迫切需要研究为早期诊断提供更好的工具。最终，这些工具将极大地帮助管理侵袭性真菌病。近年来，我们的实验室主要研究真菌发病的分子机制，重点研究生物活性脂质在这一过程中的作用，包括机制和翻译水平。我们在小鼠模型中发现，一种称为葡萄糖神经酰胺（glcer）的真菌脂质分子是新型隐球菌（Cn）侵袭性的重要调节剂，隐球菌是一种环境真菌，一旦吸入，就会引起隐球菌病，隐球菌病是一种侵袭性真菌疾病，可导致易感人群中危及生命的脑膜脑炎。特别是，我们发现，与野生型细胞相比，不产生glcer的Cn细胞被包含在肺肉芽肿中，不能扩散到中枢神经系统（CNS）。结果，宿主保持健康，没有任何脑膜-脑炎的临床症状。有趣的是，野生型细胞产生的隐球菌GlcCer引起宿主抗体反应，并且在野生型Cn细胞从肺传播到血液之前以及在脑膜脑炎发展之前，可以在小鼠血清中检测到针对GlcCer的IgM。基于这些观察结果，我们假设Cn离开肺部并感染大脑需要GlcCer，并且血清IgM对真菌GlcCer的检测可作为隐球菌病的早期诊断方法。因此，为了解决这一假设，我们提出以下目标：1)确定glcer在隐球菌病发展中的作用；2)确定抗glccer抗体对免疫功能低下人群播散性隐球菌病的预测价值。这些研究将使用我们开发的酶联免疫吸附试验进行。重要的是，由于GlcCer也由念珠菌和曲霉菌产生，这些研究结果不仅可以为隐球菌病的早期诊断提供新的方法，也可以为念珠菌病和曲霉菌病的早期诊断提供新的手段。侵袭性真菌感染，如隐球菌病、念珠菌病和曲霉病，在免疫功能低下的受试者中急剧出现。本项目旨在开发一种新的诊断方法来预测真菌感染的侵袭性，以便实施适当的治疗策略。这将对人类健康产生巨大影响，因为侵袭性真菌疾病预后非常差。

DESCRIPTION (provided by applicant): Invasive fungal infections, such as cryptococcosis, candidiasis and aspergillosis, have dramatically emerged in the last two decades and are associated with very poor prognosis. Although significant progress has been made to improve molecular and genetic tools to study their development and progression, studies to provide better tools for an early diagnosis are urgently needed. Ultimately, these tools will significantly help in the management of invasive mycoses. In recent years, our laboratory has centered on dissecting molecular mechanisms of fungal pathogenesis, focusing on the study of the role of bioactive lipids in this process both at a mechanistic and at a translational level. We discovered in our mouse model that a fungal lipid molecule called glucosylceramide (GlcCer) is an essential regulator of the invasiveness of Cryptococcus neoformans (Cn), an environmental fungus that, once inhaled, causes cryptococcosis, an invasive fungal disease which can lead to life-threatening meningo- encephalitis in susceptible human subjects. In particular, we found that, in contrast to wild-type cells, Cn cells that do not produce GlcCer are contained within lung granulomas and cannot disseminate to the central nervous system (CNS). As a result, the host remains healthy without any clinical sign(s) of meningo- encephalitis. Interestingly, cryptococcal GlcCer produced by wild-type cells elicits a host antibody response, and IgM against GlcCer can be detected in mouse sera prior to the dissemination of wild-type Cn cells from the lung to the bloodstream and prior to the development of the meningo-encephalitis. Based on these observations, we hypothesize that GlcCer is required for Cn to leave the lung and infect the brain and that the detection of serum IgM against fungal GlcCer can be used as an early diagnostic method of cryptococcosis. Thus, to address this hypothesis we propose the following aims: 1) to determine the role of GlcCer in the in the development of cryptococcosis; and 2) to determine the value of anti-GlcCer antibody for the prediction of disseminated cryptococcosis in immunocompromised subjects. These studies will be performed using an ELISA test that we have developed. Importantly, because GlcCer is also produced by Candida and Aspergillus spp., the results from these studies not only could provide a new method for the early diagnosis of cryptococcosis but could also prompt new means for the early diagnosis of candidiasis and aspergillosis. PUBLIC HEALTH RELEVANCE Invasive fungal infections, such as cryptococcosis, candidiasis and aspergillosis, have dramatically emerged in immunocompromised subjects. This project aims to develop a new diagnostic method that would predict the invasiveness of fungal infections so that appropriate treatment strategies can be implemented. This will have a dramatic effect on human health as invasive fungal diseases have very poor prognosis.