Wang Xiaocen, Gong Pengtao, Zhang Nan, Li Lu, Chen Sining, Jia Lijun, Liu Xianyong, Li Jianhua, Zhang Xichen
Key Laboratory of Zoonosis Research by Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University, Changchun, 130062, China.
Laboratory of Veterinary Microbiology, Department of Veterinary Medicine, Yanbian University, Yanji, 133002, China.
Vet Parasitol. 2019 Apr;268:16-20. doi: 10.1016/j.vetpar.2019.02.008. Epub 2019 Mar 1.
Neospora caninum is an intracellular parasite that causes neosporosis in cattle. Bovine neosporosis is considered a major cause of bovine abortion worldwide. Rapid replication of N. caninum tachyzoites within host cells is responsible for the acute phase of N. caninum infection. Evidence shows that the host immune response plays an essential role in recognizing and regulating the replication of invading pathogens. Nucleotide-binding oligomerization domain receptors (NLRs) are a class of cytoplasmic sensors that can sense pathogens and induce the formation of the inflammasome complex. Activation of the inflammasome promotes restriction of microbial replication. Our previous study revealed NLRP3 inflammasome activation in N. caninum-infected murine macrophages. However, the role of inflammasome activity in N. caninum-infected bovine cells is unknown. To address this question, a bovine peritoneal macrophage cell line was used to investigate the role of inflammasome activation in regulating intracellular N. caninum replication. The results showed that inflammasome mediated activation of caspase-1 occurs in N. caninum-infected bovine macrophages, and caspase-1-dependent cell death was considered to be induced in N. caninum-infected bovine macrophages because N. caninum induced cell death decreased following pretreatment with zVAD-fmk and VX765. Meanwhile, the inhibition of caspase-1 in N. caninum-infected bovine macrophages led to the presence of more parasites in the parasitophorous vacuole. In contrast, inflammasome activation induced by ATP treatment in N. caninum-infected bovine macrophages contributed to the clearance of N. caninum. In addition, pyroptotic cell supernatant collected from ATP-stimulated bovine macrophages also impaired the ability of this parasite to infect new cells. In conclusion, this study is the first report on the role of the bovine inflammasome in restraining intracellular N. caninum replication and suggests that the bovine inflammasome may be a potential target for future development of drugs or vaccines against N. caninum infection in cattle.
犬新孢子虫是一种细胞内寄生虫,可引起牛的新孢子虫病。牛新孢子虫病被认为是全球范围内牛流产的主要原因。犬新孢子虫速殖子在宿主细胞内的快速复制是犬新孢子虫感染急性期的原因。有证据表明,宿主免疫反应在识别和调节入侵病原体的复制中起着至关重要的作用。核苷酸结合寡聚化结构域受体(NLRs)是一类细胞质传感器,可感知病原体并诱导炎性小体复合物的形成。炎性小体的激活促进微生物复制的限制。我们之前的研究揭示了犬新孢子虫感染的小鼠巨噬细胞中NLRP3炎性小体的激活。然而,炎性小体活性在犬新孢子虫感染的牛细胞中的作用尚不清楚。为了解决这个问题,使用牛腹膜巨噬细胞系来研究炎性小体激活在调节细胞内犬新孢子虫复制中的作用。结果表明,炎性小体介导的caspase-1激活发生在犬新孢子虫感染的牛巨噬细胞中,并且caspase-1依赖性细胞死亡被认为是在犬新孢子虫感染的牛巨噬细胞中诱导的,因为用zVAD-fmk和VX765预处理后,犬新孢子虫诱导的细胞死亡减少。同时,犬新孢子虫感染的牛巨噬细胞中caspase-1的抑制导致寄生泡中存在更多的寄生虫。相反,ATP处理在犬新孢子虫感染的牛巨噬细胞中诱导的炎性小体激活有助于犬新孢子虫的清除。此外,从ATP刺激的牛巨噬细胞中收集的焦亡细胞上清液也损害了这种寄生虫感染新细胞的能力。总之,本研究首次报道了牛炎性小体在抑制细胞内犬新孢子虫复制中的作用,并表明牛炎性小体可能是未来开发抗牛犬新孢子虫感染药物或疫苗的潜在靶点。