Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences, Fudan University, Shanghai, China.
Department of Clinical Laboratory Medicine, Yangpu Hospital of Tongji University, Shanghai, China.
PLoS Negl Trop Dis. 2018 Feb 8;12(2):e0006216. doi: 10.1371/journal.pntd.0006216. eCollection 2018 Feb.
Entamoeba nuttalli is an intestinal protozoan with pathogenic potential that can cause amebic liver abscess. It is highly prevalent in wild and captive macaques. Recently, cysts were detected in a caretaker of nonhuman primates in a zoo, indicating that E. nuttalli may be a zoonotic pathogen. Therefore, it is important to evaluate the pathogenicity of E. nuttalli in detail and in comparison with that of E. histolytica.
METHODOLOGY/PRINCIPAL FINDINGS: Trophozoites of E. nuttalli GY4 and E. histolytica SAW755 strains were inoculated into liver of hamsters. Expression levels of proinflammatory factors of hamsters and virulence factors from E. histolytica and E. nuttalli were compared between the two parasites. Inoculations with trophozoites of E. nuttalli resulted in an average necrotic area of 24% in liver tissue in 7 days, whereas this area produced by E. histolytica was nearly 50%. Along with the mild liver tissue damage induced by E. nuttalli, expression levels of proinflammatory factors (TNF-α, IL-6 and IL-1β) and amebic virulence protein genes (lectins, cysteine proteases and amoeba pores) in local tissues were lower with E. nuttalli in comparison with E. histolytica. In addition, M2 type macrophages were increased in E. nuttalli-induced amebic liver abscesses in the late stage of disease progression and lysate of E. nuttalli trophozoites induced higher arginase expression than E. histolytica in vitro.
CONCLUSIONS/SIGNIFICANCE: The results show that differential secretion of amebic virulence proteins during E. nuttalli infection triggered lower levels of secretion of various cytokines and had an impact on polarization of macrophages towards a M1/M2 balance. However, regardless of the degree of macrophage polarization, there is unambiguous evidence of an intense acute inflammatory reaction in liver of hamsters after infection by both Entamoeba species.
内蜒阿米巴是一种具有潜在致病性的肠道原生动物，可导致阿米巴性肝脓肿。它在野生和圈养猕猴中高度流行。最近，在动物园的非人类灵长类动物饲养员中检测到包囊，表明内蜒阿米巴可能是一种人畜共患病病原体。因此，详细评估内蜒阿米巴的致病性，并与溶组织内阿米巴进行比较是很重要的。
方法/主要发现：将内蜒阿米巴 GY4 和溶组织内阿米巴 SAW755 株的滋养体接种到仓鼠肝脏中。比较两种寄生虫的仓鼠前炎症因子表达水平和溶组织内阿米巴和内蜒阿米巴的毒力因子。内蜒阿米巴滋养体接种后 7 天，肝组织的平均坏死面积为 24%，而溶组织内阿米巴的这一面积接近 50%。随着内蜒阿米巴引起的肝组织损伤轻微，与溶组织内阿米巴相比，局部组织中前炎症因子（TNF-α、IL-6 和 IL-1β）和阿米巴毒力蛋白基因（凝集素、半胱氨酸蛋白酶和阿米巴孔）的表达水平较低。此外，在疾病进展的晚期，M2 型巨噬细胞在内蜒阿米巴诱导的肝脓肿中增加，并且内蜒阿米巴滋养体裂解物在体外诱导的精氨酸酶表达高于溶组织内阿米巴。
结论/意义：结果表明，内蜒阿米巴感染过程中阿米巴毒力蛋白的差异分泌导致各种细胞因子的分泌水平降低，并影响巨噬细胞向 M1/M2 平衡的极化。然而，无论巨噬细胞极化程度如何，两种内阿米巴感染后，仓鼠肝脏均有明显的强烈急性炎症反应证据。
