旋毛虫诱导分化的巨噬细胞调节弓形虫再感染的分子机制

The zoonotic Trichinella spiralis and Toxoplasma are important foodborne parasites. Coinfection of Trichinella spiralis and Toxoplasma changes the immune responses against each parasite, further raises the food security concerns and leads to great threaten for human health. The pathogenicity and immunologic mechanism of the two parasites living in one host is one of crucial issues in prevention and control of coinfection of Trichinella spiralis and Toxoplasma. The aim of the study is to investigate on the polarization of macrophages induced by Trichinella spiralis and its impact on the Toxoplasma infection using genetic engineering and immunologic technologies. The macrophages induced by Trichinella spiralis excreted/secreted antigens (TsESA) in vitro will detected the expression of M(TsESA) markers, and then will be determined the regulatory mechanism on succeeded Toxoplasma infection. The impact of Trichinella spiralis infection at different infective doses on Toxoplasma succeeded infection will be performed. The molecular mechanism of macrophage activated by Trichinella spiralis through IL-4/STAT6 pathway and the impact of Trichinella-induced macrophage on the Toxoplasma infection will be determined using the experimental system that is Trichinella spiralis infection preceded Toxoplasma infection in wild type, IL-4- and STAT6- mice. Expected results will provide new ideas for prevention and control of coinfection of Toxoplasma and Trichinella spiralis, and also will provide the “foundation-data” for further development of new vaccines and drags against the coinfection.

旋毛虫与弓形虫是两种危害严重的食源性人兽共患寄生虫。两种病原的共感染改变了宿主对每种病原的免疫应答反应，进一步增加了对食品安全和人类健康的威胁。阐明旋毛虫与弓形虫感染同一宿主的致病机理和免疫机制是防控两种病原共感染的重点。本项目采用分子生物学和免疫学相关技术，研究由旋毛虫诱导分化的巨噬细胞对弓形虫再感染的调节机制。将旋毛虫代谢分泌抗原与巨噬细胞共培养，鉴定巨噬细胞的表型，体外实验研究分化的巨噬细胞对弓形虫再感染的调节作用。利用旋毛虫-弓形虫依次分别感染野生型、IL-4-和STAT6-小鼠的实验模型，阐明不同旋毛虫感染量对小鼠再感染弓形虫的影响，明确旋毛虫通过IL-4/STAT6信号通路诱导巨噬细胞分化的分子机制及对弓形虫再感染调节的作用机理。上述研究可为防控两种病原共感染奠定理论基础，同时为研制针对两种病原共感染的疫苗或药物提供充分的科学依据。

在自然界中，寄生虫、病毒、细菌共同寄生在哺乳动物肠道内的现象普遍存在。多种病原的共感染会改变宿主对每种病原的免疫应答反应，进而增加了防控难度和对人类健康的威胁。本项目的研究发现，旋毛虫感染后导致弓形虫在小鼠脑组织内形成的包囊数显著增加。旋毛虫感染小鼠后，血清中IL-4含量增加，INF-γ分泌量减少，CD4+ T细胞比例上升，引起了Th2型免疫应答反应。进一步，通过旋毛虫代谢分泌抗原（ESA）体外刺激巨噬细胞，发现巨噬细胞M2型标志分子Arg-1、MRC-1等上调表达，且可以体外诱导CD4+ T细胞活化和增殖。进一步地，通过对弓形虫感染经旋毛虫ESA刺激的巨噬细胞的研究，发现巨噬细胞内弓形虫的荷虫量较未刺激的巨噬细胞无显著变化。但在旋毛虫-弓形虫依次感染的小鼠体内，弓形虫的脑包囊数量较未感染旋毛虫小鼠脑包虫的数量显著增多，且随着旋毛虫感染剂量的增加而增加。本研究为防控两种病原共感染奠定理论基础。项目资助发表SCI论文4篇，申报发明专利1项，培养研究生1名在读。项目投入经费18万元，支出17.2825万元，支出与预算基本相符。