小鼠泡型包虫病浸润转移的动态代谢组学研究

Alveolar echinococcosis (AE), caused by the larval stage of Echinococcus multilocularis, is considered to be one of the most lethal parasitic zoonoses for humans worldwide. AE is highly endemic over the large areas of north-western provinces and autonomous regions of China. It was estimated that 91% new cases of AE per annum globally occurring in China. The national control program on echinococcosis has been launched in the country in 2005. In 2007, the central government listed echinococcosis as one of the six serious infectious diseases receiving free treatment. The infiltrative, tumor-like growth of the E. multilocularis metacestode usually affects the liver of intermediate hosts such as humans or rodents. In untreated or inadequately treated AE cases, the mortality could be high up to >90% within 10-15 years. Therefore, early diagnosis and treatment is a paramount measure in the control activity. However, in most cases, no clinical symptoms become evident until 10 or more years after the initial infection, when the disease is already well-advanced. The diagnosis of AE is currently based on the identification of cyst structures by imaging techniques, predominantly ultrasonography. However, the imaging techniques do not offer a good prospect for early diagnosis which reduced the quality of the management and treatment of the disease. According to the experimental model of E. multilocularis metacestode secondary infection in mice, which well mimics the natural infection, the clinical course of AE is divided into three stages, they are: 1) an early stage with tumor-like growth of the metacestode and mild hepatic enlargement, 2) a middle stage with invasive parasitic lesions and progressive hepatomegaly and 3) the late stage associated with invasion to other organs and/or metastases, fibrosis of the lesions and cholestasis. To date, the molecular mode of the infiltration and metastasis is little known. In this study, we will systematically investigate the time-course of the metabonomic changes in urine, blood plasma and the liver tissues of the secondary infected mice by E. multilocularis metacestode. A comprehensive mapping of the specific metabolite composition at the early, middle and late stages in the murine model of AE will be established by using 1H NMR spectroscopy and multivariate data analysis. The main objectives are to define the host metabonomic responses to the infection at the early stages and their dynamic changes during the disease progression, which are of potential importance to provide clues for the development of early diagnosis method and for further understanding of the host molecular response to the infection of E. multilocularis.

泡型包虫病是泡状棘球蚴寄生于人、兽体内引起的世界范围内危害严重的人兽共患寄生虫病。该病在我国西部青藏高原地区流行严重。早期诊断和治疗对病人的生存状况至关重要。由于对泡球蚴发生浸润转移的分子机制不清楚，目前尚缺乏有效的早期诊断方法，影响了防治效果。泡球蚴寄生于小鼠体内引起的病理过程与在人体内非常相似，分为早期浸润期，中期钙化期，晚期液化空洞期。本课题拟采用1H核磁共振技术，研究泡球蚴浸润转移过程早、中、晚三期小鼠的肝脏，血浆及尿液动态代谢组学，建立疾病进程代谢轮廓图谱，并采用主成分分析（PCA）联合偏最小二乘（PLAS-DA）多变量统计法对图谱进行判别，以筛选并鉴定疾病的内源性代谢标志物群；并运用生物信息学方法建立疾病相关的代谢途径及代谢网络，旨在分析泡球蚴浸润转移过程宿主内源性代谢物动态响应规律，并筛选早期标志物，为发展早期诊断方法，理解致病机制提供依据。

泡型包虫病是我国重大寄生虫病和西部藏区的地方病，严重危害当地人民的身体健康和社会经济发展。目前对该病的致病机制研究滞后及早期诊断技术欠缺，影响了对病人的及时发现和治疗。本研究采用新近发展的核磁共振代谢组学方法，从整体水平研究泡球蚴感染早期和晚期的小鼠模型体液（血液，尿液）和组织（肝脏，脾脏）的动态代谢应答及规律，通过对疾病特异性代谢物的筛选和鉴定，描述疾病进程宿主代谢物轮廓图谱，分析泡球蚴致病的分子机制并发现潜在的早期感染相关标志物。取得如下重要结果：1. 在感染较早期的小鼠体液中发现19种，组织中发现30种疾病相关代谢物；2. 感染晚期的小鼠体液中发现8种，组织中发现30种疾病相关代谢物；3. 共完成了68种差异代谢物的鉴定与归属。其中，41种属于感染早期相关，且28种可贯穿疾病全程，这些代谢物对疾病早期诊断有提示作用；4. 发现的代谢物可主要归属于8条代谢途径，提示这些代谢途径可能跟泡球蚴的致病紧密相关，是今后研究的重点。代谢物是生物系统病理生理状态改变的最终结果和真实反映，对于理解病因，开展诊断和治疗具有重要参考价值。本研究结果从整体水平较详细的解析了泡球蚴致病过程宿主内源性代谢物的变化规律，为今后深入开展泡球蚴致病分子机制和早期诊断方法研究奠定了基础，并为开展临床包虫病代谢组学研究提供了方法论支持和技术储备。