蜱是畜牧传染病的最主要传播者, 给畜牧业带来严重的危害，同时它也传播莱姆病、流行性出血热等重大人类疾病。蜱是专性吸血的节肢动物，硬蜱侵入宿主后，要在体表停留吸血1-2个星期，这么长的吸血时间内完全可以启动宿主的免疫排斥反应。
为了成功地从其宿主获得血液，蜱发展了完善的免疫抑制系统以逃避宿主的免疫排斥反应。长期以来，世界多个实验室都已经发现了蜱唾液腺可以分泌免疫抑制剂，但一直没有分离和鉴定到免疫抑制剂多肽分子。
最近中国科学院昆明动物研究所赖仞研究员领导的研究团队从硬蜱唾液腺中分离和识别了两个家族的免疫抑制剂多肽，并对这些免疫抑制剂多肽的作用机制和相关的信号途径进行了深入的研究。发现这两个家族的多肽由同一个基因编码，它们通过作用于MAPK信号途径调节宿主细胞因子的分泌而发挥免疫抑制功能。这是世界上从蜱唾液腺中发现的免疫抑制剂多肽活性分子的首次报道。该发现对理解蜱与宿主相互作用的分子机制以及发展蜱的生物控制策略具有重要意义。
生物谷推荐原文出处：
JBC doi: 10.1074/jbc.M109.094615
Two immunoregulatory peptides with antioxidant activity from tick salivary glands
Jing Wu1, Yipeng Wang1, Han Liu1, Hailong Yang1, Dongying Ma1, Jianxu Li1, Dongsheng Li1, Ren Lai1 and Haining Yu2,*
1 Kunming Institute of Zoology, Chinese Academy of Sciences, China;
2 Dalian University of Technology, China
Ticks are blood feeding arthropods that may secrete immunosuppressant molecules, which inhibit host inflammatory and immune responses and provide survival advantages to pathogens at tick bleeding sites in hosts. In current work, two families of immunoregulatory peptides, hyalomin A and B were firstly identified from salivary glands of hard tick Hyalomma asiaticum asiaticum. Three copies of them are encoded by identical gene and released from the same protein precursor. Both hyalomin A and B can exert significant antiinflammatory functions, either by directly inhibiting the host secretion of inflammatory factors such as TNF alpha, MCP1 and IFN gamma, or by indirectly increasing the secretion of immunosuppressant cytokine of IL10. Hyalomin A and B were both found to potently scavenge free radical in vitro in a rapid manner, and inhibited adjuvant induced inflammation in mouse models in vivo. The JNK SAPK subgroup of MAPKs signaling pathway was involved in such immunoregulatory functions of hyalomin A and B. These results showed that immunoregulatory peptides of tick salivary glands suppress host inflammatory response by modulating cytokine secretion and detoxifying reactive oxygen species.
