细粒棘球蚴感染中Tim-3/Galectin-9介导的免疫逃避机制研究

Hydatid disease (Cystic Echinococcosis，CE) is a zoonotic helminthic disease which has bean a serious in the westen China. It is difficult to prevent and treat this infection. Previous studies showed that the Tim-3/Galectin-9 pathway can induce immune tolerance and play important roles in pathogenesis and tumor immune escape. However, the effect of Tim-3/Galectin-9 pathway on CE escape is still unclear. Here, flow cytometry has been used to observe the change character of Tim-3/Galectin-9 in different stages of E. granulosus infected mice. Meanwhile, with the study about blocking Tim-3/Galectin-9 pathway by soluble Tim-3 or specific antibody to clarify the relationship between Tim-3/Galectin-9 signal pathway and infection, we will explore the immune escape mechanism that the Tim-3/Galectin-9 mediated. We focus on the regulation of E. granulosus antigen to the Tim-3/Galectin-9 pathway by observing the change character of Tim-3/Galectin-9 before and after Eg95and EgB stimulating. This study will provide a new direction for recovering research E. granulosus molecular pathogenesis mechanism and provide the insight for developing immune strategies against the E. granulosus infection.

包虫病为新疆牧区严重的寄生虫病，对其发病机制认识不足，阻碍了对其有效疫苗的研制。免疫调节分子Tim-3与配体Galectin-9形成信号通路的激活在肿瘤免疫逃逸中发挥重要作用，但其在包虫病的作用尚未阐明。我们前期发现Treg细胞参与了棘球蚴的免疫逃避，但其机制尚不清楚。本项目以Tim-3/Galectin-9通路的免疫负调控为切入点，研究手术前后包虫病患者和Eg感染小鼠Tim-3/Galectin-9信号通路的激活，明确其与Eg感染病程的关系；通过Tim-3阻断，分析Tim-3/Galectin-9在Treg免疫抑制功能中发挥的作用及机制，阐明Tim-3/Galectin-9通路在宿主免疫抑制状态形成和维持上所起的作用；用EG95疫苗和EgB调节Tim-3/Galectin-9，阐明包虫抗原与宿主免疫应答关系，为设计有效保护性疫苗和开展以阻断免疫逃避信号途径为靶点的包虫病防治研究提供新思路

棘球蚴病是严重的人畜共患病，我国是棘球蚴病高发的国家之一，新疆地区以细粒棘球蚴病（CE）多见，也是影响新疆牧民身体健康的因素之一。由于其发病机制不清，阻碍了有效的防控措施和疫苗的研究。围绕Tim-3与galectin-9结合，产生抑制性信号，诱导效应T细胞凋亡，在免疫应答中起到负性调节的作用。本课题检测包虫病患者外周血中Galectin9及TIM-3在CD4+T细胞表达和功能改变，发现Galectin-9和Tim-3在CE患者外周血Treg细胞上表达水平明显高，治疗后CE患者其水平均明显下降，相关的细胞因子IL-4、IL-10、TGF-β也同样变化。Tim-3/Galectin-9通路的阻断降低了CE患者Treg细胞抑制异源性的CD4+T细胞的活化的能力，并降低异源性的CD4+T细胞的凋亡，明确了Galectin-9/Tim-3通路激活与棘球蚴感染的寄生有关。结合最新文献认为HMGB1是另一配体，本课题发现Tim-3/HMGB1在活动性和非活动性CE患者中的表达差异明显，观察Tim-3/HMGB1在活动性CE患者治疗后的下降，明确了TIM-3与配体结合后包虫的活动性和转归有关。在棘球蚴感染动物模型研究中发现细粒棘球蚴感染小鼠肝脏中Tim-3和Galectin-9的表达随着感染时间延长表达量明显增加，棘球蚴囊的重量也增加明显，anti-Tim-3的小鼠体内阻断Tim-3/Galectin-9通路，Galectin-9和Tim-3在肝脏中的表达均降低，表明Tim-3和Galectin-9参与棘球蚴囊泡的生长，这为进一步研究以此通路为靶点的抗棘球蚴感染的免疫治疗提供了新的思路。根据新的文献报道血清中IL-9水平与许多疾病有关，因此本课题研究了包虫病患者的Th9细胞在治疗前后的改变，发现患者外周血IL-9表达量和Th9细胞升高，在棘球蚴感染动物模型晚期Th9细胞居高不下，为进一步开展Th9细胞和IL-9在包虫感染的致病机制奠定了基础。