S100A4+巨噬细胞亚群在寨卡病毒感染引起睾丸损伤中的作用及机制研究

Sexual transmission and testicular damage is one of the important characteristics of the zika virus (ZIKV) infection. ZIKV infected male mice demonstrated the viral replication in testis, testicular damage, atrophy, fibrosis as well as spermatogenesis, but the mechanism remains to be addressed. We have recently found that ZIKV infection in mice was accompanied with the appearance of a large number of S100A4+ macrophages subpopulation in testis. Moreover, the emerging and disappearance of S100A4+ macrophage in testis coincided with the testicular dynamic of ZIKV, the fibrosis of seminiferous tubule, and the reduce of the sperm cells, thus suggesting S100A4+ macrophages might play essential role in testicular injury caused by ZIKV injury. The current project therefore, by using the newly established S100A4 knockout and report gene carrying mice, intends to validate the susceptibility of S100A4+ macrophage to ZIKV infection, clarify their involvement in testicular injury caused by ZIKV infection, analyze the influence of ZIKV infection on their function and gene expression, and explore the protective effects of S100A4 neutralizing antibody. The results are expected to deeply reveal the mechanism of testicular injury induced by ZIKV infection, and to provide new strategies and tools for the prevention and control of ZIKV epidemic as well as the maintenance of male reproductive health in China.

性传播及睾丸损伤是寨卡病毒（ZIKV）有别于其它蚊媒黄病毒的重要特征之一。雄性小鼠感染ZIKV后出现睾丸内病毒增值、睾丸损伤、萎缩、纤维化及生精细胞减少等病变，但机制不明。申请人最近发现小鼠感染ZIKV后，睾丸内可出现大量S100A4+巨噬细胞亚群，其在睾丸内的兴衰正与病毒在睾丸的损伤、曲精小管的纤维化、以及生精细胞的减少相吻合，提示S100A4+巨噬细胞在ZIKV损伤睾丸过程中发挥了重要作用。本项目因此拟利用新建的S100A4敲除小鼠及携带报告基因的小鼠，明确S100A4+巨噬细胞对ZIKV在睾丸内增殖的支持作用，阐明它们在ZIKV损伤睾丸中的促进作用，分析ZIKV感染对它们的功能和基因表达的影响，并且探索S100A4中和抗体的保护作用。研究结果有望从S100A4+巨噬细胞入手，深入解析ZIKV感染所致睾丸损伤的机制，并为我国防治ZIKV流行及维护男性生殖健康提供新的策略和工具。

性传播和睾丸损伤是ZIKV有别于其它蚊媒黄病毒的显著特征之一，也是它威胁人类健康的重要原因，然而其致病的详尽机制尚不清楚，参与的关键因子也有待鉴定。本项目以S100A4+巨噬细胞亚群为切入点，利用S100A4/GFP报告基因小鼠及S100A4基因敲除小鼠等手段，希望完成以下4项目标：（1）明确S100A4+巨噬细胞对ZIKV在睾丸内增殖的支持作用；（2）阐明S100A4+巨噬细胞在ZIKV损伤睾丸中的促进作用；（3）分析ZIKV感染对S100A4+巨噬细胞的功能和基因表达的影响；（4）评价S100A4中和抗体的保护作用。经过4年研究，本项目现已阐明：（1）S100A4+巨噬细胞对ZIKV具有易感性，且能在睾丸内存在较长时间，因此能够作为靶细胞维持ZIKV在睾丸的复制，（2）S100A4+巨噬细胞感染ZIKV后，能够分化为M1型巨噬细胞，通过分泌IFN-γ破坏血睾屏障，（3）S100A4+巨噬细胞感染ZIKV后，能够上调表达并分泌补体成分，通过经典的补体激活途径导致生精细胞损伤，（4）发现S100A4的抑制剂氯硝柳胺能够降低睾丸内ZIKV病毒载量，保护ZIKV感染所导致的睾丸损伤，并已获得国家发明专利。截止2022年底，本项目已在《PLoS Pathogens》、《Journal of Virology》等病毒学一流期刊发表基金标注的相关SCI论文5篇，在《病毒学报》等国内主流病毒学期刊发表中文论文3篇，另外还有2篇文章在投；获得《氯硝柳胺在制备预防和/或治疗缓解寨卡病毒感染所致睾丸损伤的药物中的应用》国家发明专利1项；培养博士研究生3人，其中1人获得北京市优秀毕业生荣誉。本项目的研究结果加深了我们对ZIKV损伤睾丸的认识，有助于全面深入理解ZIKV感染后睾丸病变的机制，同时发现的S100A4抑制剂氯硝柳胺也有望为治疗ZIKV所致睾丸损伤提供新手段。