蜱唾液蛋白的免疫生物学活性及其在疫苗开发和抗炎性疾病中的应用

Tick-borne diseases attracted widespread attention in recent years. Our previous work suggested that tick saliva proteins can not only contribute to tick feeding, but also help the tick-borne pathogens to evade the local immune response of the host and to improve pathogen survival. The mice were significantly protected from tick transmitted infection of Lyme diseases agent, when the key saliva proteins were blocked. This will be a novel strategy for vaccine development against vector-borne diseases. In this project, we will focus on several tick saliva proteins that differentially expressed in pathogen infected and non-infected ticks; demonstrate their detail immune biological functions, reveal their relationships with the transmission of pathogens, and explore the possibility of these saliva proteins as anti-tick vaccines, as well as immunosuppressants against inflammatory immune diseases. In vitro experiments, gene silencing, active immunization, mouse infection and inflammatory disease models will be used in this study to investigate the function and application of key candidate immunosuppressive protein P11 and TACPLs. Considering that the researches on pathogen vector and saliva proteins are relatively rare in China, this project will help to understand the mechanisms of the transmission of vector-borne pathogens, and provide new ideas for the prevention and control of vector-borne diseases.

蜱虫传染病近年来引起了广泛关注。我们前期的工作揭示，蜱虫的唾液蛋白不仅帮助蜱虫有效吸血，还能帮助蜱传病原体逃避宿主免疫反应，有利于病原体存活。阻断几个关键蜱虫唾液蛋白，能显著降低小鼠莱姆病病原体感染水平；这将是针对虫媒传染病疫苗开发的新思路。本项目将在前期工作的基础上，重点关注几个在病原体感染的蜱虫中差异表达的唾液蛋白，研究其免疫生物学活性，揭示它们与病原体传播的关系，探讨它们作为抗蜱传疾病疫苗的可能性，以及作为免疫抑制剂在抗炎性疾病中的应用。我们将采用体外实验、基因沉默、主动免疫、小鼠感染，以及炎性疾病动物模型等手段，深入研究重点候选蜱虫免疫抑制蛋白P11，TACPLs的生物学功能及其应用。目前国内对医学媒介昆虫唾液蛋白功能的研究还相对较少，本项目的研究将有助于揭示虫媒传染病的传播机制，为虫媒传染病的防治提供新的思路。

蜱虫等医学媒介生物能传播多种导致人类疾病的病原体。蜱虫的唾液中含有大量生物活性的分子，抑制不同的宿主防御机制。这些物质帮助蜱麻痹宿主，从而更有效的吸血；同时帮助它所传播的病原体逃避宿主局部的免疫反应，提高了这些病原体的早期存活几率。通过本项目的研究，我们从几种中国境内的蜱虫中鉴定了一系列具有免疫调节活性的媒介唾液蛋白。其中, 着重研究了从中国东北的森林革蜱中克隆分离到的分泌型唾液蛋白DsCystatin的免疫抑制功能及其应用。重组表达的DsCystatin蛋白能抑制人组织蛋白酶L和B的酶活性。DsCystatin可以抑制由LPS或伯氏疏螺旋体刺激的小鼠骨髓分化的巨噬细胞的活化，及IL1β, TNFα等炎性细胞因子mRNA和蛋白水平的表达。DsCystatin可以抑制LPS或伯氏疏螺旋体对TLR信号通路下游NFκB的激活。进而发现DsCystatin通过诱导自噬来促进TRAF6的降解，从而达到抑制NFκB活化的目的。最后，我们研究了DsCystatin在小鼠炎症模型中的作用。在弗氏完全佐剂或伯氏疏螺旋体诱导的小鼠关节炎症疾病模型中，DsCystatin可以减轻炎症的发生，并可以缓解小鼠关节的肿胀。这些数据表明来自森林革蜱的分泌型唾液蛋白DsCystatin是一种新的免疫抑制蛋白，能够抑制天然免疫细胞的活化，并且在治疗或缓解炎症性疾病中存在潜在价值。基于蜱虫唾液蛋白生物学活性的相关研究结果发表了一系列SCI论文。此外，我们新发现的Cystatin及其免疫抑制作用，已经获得了国家发明专利的授权，这为进一步开发基于节肢动物蛋白的抗炎症多肽药物提供了基础。