RNA和DNA感受器介导的睾丸天然免疫反应与病毒性睾丸炎

Viral orchitis is one of the major etiological factors of male infertility. The mammalian testis is a remarkable immunoprivileged organ, which may be infected by various pathogens. The testis adopts effective local innate defense system against microbial infections. However, various virus infections would disrupt the testicular immune homeostasis, resulting in orchitis and male infertility. Thus, the testicular immunoregulation is an important issue in reproductive immunology. In this proposal, we will use RNA and DNA viruses infected mouse model to investigate the correlation of RNA and DNA sensor-initiated innate antiviral response and orchitis, as well as their deleterious impacts on spermatogenesis. Two specific aims will be focused in this proposal: (1) to clarify the relationship between testicular innate immune response and inflammation through ligands activation or viral infection; (2) to study the molecular mechanism of RNA/DNA sensors mediated innate immune response by using RNAi technology and knockout mouse model. Outcomes of this study will provide novel insights into the mechanisms underlying the testicular innate immune responses and their effects on male fertility, which can aid in establishing preventive and therapeutic targets for virus-related male infertility. The project is expected to train 2-3 graduate students, and publish 2 papers on the professional SCI journals.

病毒性睾丸炎是引起男性不育的重要病因。睾丸是典型的免疫豁免器官，容易受到多种病原体的感染，为了有效抵御病原体，睾丸建立了局部天然免疫防御机制。但某些病毒感染可破坏睾丸免疫稳态，从而导致睾丸炎，睾丸免疫环境的调节机理是生殖免疫学领域广泛关注的重要科学问题。本项目拟利用RNA病毒和DNA病毒感染的小鼠睾丸炎模型，系统研究RNA/DNA感受器介导的睾丸天然免疫反应与睾丸炎的关系、及其对精子发生的影响。主要内容包括：（1）通过配体激活或病毒感染，研究睾丸天然免疫反应与睾丸炎的关系；（2）利用RNAi技术和敲除小鼠模型，研究RNA/DNA感受器介导睾丸细胞天然免疫反应的分子机制。目的是揭示病毒感染诱导睾丸炎及导致雄性不育的机制，认识关键调控环节，为防治相关疾病提供干预靶点。项目拟培养研究生2-3人，在领域内主流SCI杂志上发表论文2篇。

哺乳动物睾丸是机体内的重要的免疫豁免器官，容易受到病毒侵袭引发病毒性睾丸炎。病毒性睾丸炎常常会引起睾丸功能损伤并严重影响雄性生殖能力，但病毒感染睾丸的致病机理仍不清楚。本研究利用人工合成的病毒核酸类似物poly（I:C）和HSV60分别模拟病毒RNA和DNA在睾丸细胞中的感染，来研究不同类型病毒在睾丸Sertoli细胞和Leydig细胞中激活天然免疫途径的差异，以及对细胞功能及睾丸精子发生的影响。同时，比较野生型RNA病毒ZIKV和DNA病毒HSV2感染对睾丸细胞功能的影响。此外，利用小鼠体外、体内模型着重研究了MuV感染损伤BTB形成的机制。结果发现睾丸原位注射poly（I:C）会引起生精上皮变薄、精子发生受阻，而HSV60则不会影响睾丸组织形态。细胞水平结果显示poly（I:C）可激活Sertoli细胞和Leydig细胞中的NF-κB和IRF3信号，但Sertoli细胞比Leydig细胞产生更高水平的促炎细胞因子TNF-α和IL-6。HSV60主要激活Leydig细胞中的IRF3信号，并诱导I型干扰素（IFNα/β）和多种抗病毒蛋白表达升高。TLR3和IPS-1协同介导poly（I:C）激活的细胞炎性反应和抗病毒反应，而STING介导HSV60激活细胞的抗病毒反应。细胞功能实验结果发现poly（I:C）会破坏Sertoli细胞BTB结构的形成并抑制Leydig细胞合成睾酮，而HSV60无明显影响。野生病毒感染实验显示ZIKV更易损害睾丸细胞功能。此外，MuV能特异地抑制紧密连接蛋白Occludin和ZO-1的表达和细胞膜定位，从而破坏了BTB的结构和功能，且这一过程是由激活TLR2-TNF-α介导的天然免疫反应引起的。以上结果阐明了病毒感染过度激活的睾丸细胞促炎性反应是病毒性睾丸炎发生的致病机理，并证明了TNF-α是损伤睾丸功能的重要介质。