Oh Y-H, Jeong S-R, Kim J-H, Song K-J, Kim K, Park S, Sohn S, Shin H-J
Department of Microbiology, Institute for Medical Science, Ajou University School of Medicine, Suwon, Korea.
Parasite Immunol. 2005 Dec;27(12):453-9. doi: 10.1111/j.1365-3024.2005.00799.x.
Naegleria fowleri, a free-living amoeba, causes fatal primary amoebic meningoencephalitis in experimental animals and humans. The nfa1 gene (360 bp) was previously cloned from a cDNA library of pathogenic N. fowleri by immunoscreening, and produced a 13.1-kDa recombinant protein that showed pseudopodia-specific localization by immunocytochemistry. On the basis of an idea that the pseudopodia-specific Nfa1 protein seems to be involved in the pathogenicity of N. fowleri, the cytopathic activity of N. fowleri trophozoites co-cultured with rat microglial cells was observed, and the effects of an anti-Nfa1 antibody in a co-culture system were elucidated. Using light, scanning and transmission electron microscopy, it was seen that N. fowleri trophozoites in contact with microglial cells produced vigorous pseudopodia and a food-cup structure. Microglial cells were destroyed by N. fowleri trophozoites as seen from necrotic cell death in a time-dependent manner. In a(51)Cr release assay, N. fowleri showed 17.8%, 24.9%, 54.6% and 98% cytotoxicity against microglial cells at 3, 6, 12 and 24 h post-incubation, respectively. However, when anti-Nfa1 antibody was added in a coculture system, N. fowleri cytotoxicity was reduced to 15.5%, 20.3%, 46.7% and 66.9%, respectively. Moreover, microglial cells co-cultured with N. fowleri trophozoites secreted the pro-inflammatory cytokines, TNF-alpha, IL-1beta and IL-6. In the presence of anti-Nfa1 antibody, the secretion of TNF-alpha was slightly, but not significantly, decreased.
福氏耐格里阿米巴是一种自由生活的变形虫，可在实验动物和人类中引起致命的原发性阿米巴脑膜脑炎。nfa1基因（360 bp）先前通过免疫筛选从致病性福氏耐格里阿米巴的cDNA文库中克隆出来，并产生了一种13.1 kDa的重组蛋白，通过免疫细胞化学显示其具有伪足特异性定位。基于伪足特异性Nfa1蛋白似乎参与福氏耐格里阿米巴致病性的观点，观察了与大鼠小胶质细胞共培养的福氏耐格里阿米巴滋养体的细胞病变活性，并阐明了抗Nfa1抗体在共培养系统中的作用。通过光学显微镜、扫描电子显微镜和透射电子显微镜观察到，与小胶质细胞接触的福氏耐格里阿米巴滋养体产生了活跃的伪足和食物杯结构。从小胶质细胞的坏死性细胞死亡可以看出，小胶质细胞被福氏耐格里阿米巴滋养体以时间依赖性方式破坏。在（51）Cr释放试验中，福氏耐格里阿米巴在孵育后3、6、12和24小时对小胶质细胞的细胞毒性分别为17.8%、24.9%、54.6%和98%。然而，当在共培养系统中加入抗Nfa1抗体时，福氏耐格里阿米巴的细胞毒性分别降至15.5%、20.3%、46.7%和66.9%。此外，与福氏耐格里阿米巴滋养体共培养的小胶质细胞分泌促炎细胞因子TNF-α、IL-1β和IL-6。在抗Nfa1抗体存在的情况下，TNF-α的分泌略有下降，但不显著。
Zotero 插件