基于全基因组重测序发现的基因变异与晚期血吸虫病的相关性研究

Schistosomiasis is the major preventive parasitic disease in China. While reduce the morbidity of the disease, prevention of advanced schistosomiasis is becoming especially important. Recently, our team conducted a whole genome re-sequencing project on patients with different types of schistosomiasis. Based on the strict comparison standard (a specific mutation that either occurs or does not occur in all cases), 314 genetic loci that might cause changes in functions were identified by comparing the simple chronic schistosomiasis group with the simple advanced schistosomiasis group, and the chronic schistosomiasis co-infected with hepatitis B virus group with the advanced schistosomiasis co-infected with hepatitis B virus group. We found genes related to the TLRs signaling pathways (UNC93B1) and fibrosis-associated genes (APOB and CCR2), and it is highly probable that these are susceptibility genes for advanced schistosomiasis, according to a literature review. Thus, this study aims to investigate the mutation frequency of these three genes in a population-based sample of independent individuals, and to identify the candidate genes that are highly related to advanced schistosomiasis. Animal experiments will be conducted using schistosoma-infected knockout mice, and the pathological changes after infection with schistosoma will be observed to confirm the association between these candidate genes and advanced schistosomiasis, and to provide candidate molecules for novel molecular prediction and diagnosis techniques of advanced schistosomiasis. This study will provide key technical support for precise prevention and control of advanced schistosomiasis, and has important implications for prolonging survival and improving the quality of life in advanced patients.

血吸虫病是我国重点防治的寄生虫病。在控制疫情的同时，预防晚期血吸虫病（晚血）尤为重要。我们近期开展了不同类型血吸虫病患者全基因组重测序研究，按“全有或全无变异”的比对标准，在对单纯慢血组与单纯晚血组，以及慢血合并乙肝感染与晚血合并乙肝感染组的基因序列比对中，发现314个在编码区可能造成功能改变的基因位点，包括与TLRs信号传导相关的基因（UNC93B1），以及与纤维化相关的基因（APOB、CCR2）等。结合文献复习，推测这些基因可能是晚血的易感基因。为此，本研究拟在大样本独立人群中，对这三个基因的突变频率作调查分析，筛选出与晚血有显著相关的候选基因；利用基因敲除小鼠进行血吸虫感染实验研究，观察小鼠病理变化，从而证实候选基因与晚血发生的相关性，为建立可用于晚血预测诊断技术提供候选靶分子。本项目的完成，将为实施晚血精准预防与治疗提供关键技术支撑，对提高晚血患者的存活率和生存质量具有重要的意义。

通过日本血吸虫病病人全基因组重测序结果的对比分析及基因功能注释分析，我们初步鉴定除了与不同程度日本血吸虫病肝纤维化相关的脂代谢通路相关基因。包括APOB、PECR、HELZ2、PLA2G2D、PPARG这五个基因。基于第一阶段全基因重测序的发现，我们将5个脂代谢相关基因在更大样本量人群验证，结果证实了这些基因的遗传变异与不同程度日本血吸虫病肝纤维化之间的显著关联，此外，人血清PLA2G2D和三种炎症相关脂质介质的浓度水平在不同纤维化程度者也有显著差异，体外实验证实与PLA2G2D突变体酶活性是野生型基因型的四倍。并且PPARG突变降低了对下游启动子的能力。小鼠模型的实验结果支持肝脏脂质变化与日本血吸虫感染诱导的肝纤维化的进展相关。本课题研究不仅确认了日本血吸虫病病人在肝细胞脂代谢方面存在遗传多态性，揭示了血吸虫感染过程与肝细胞脂代谢之间的关联，更重要的是从脂代谢角度寻找临床治疗及逆转血吸虫病的有效药物及治疗靶点，对阻断肝纤维化发生，减缓病程，改善患者生存质量具有重要的临床意义。