Escuela de Ciencias de la Salud, Universidad del Valle de México, Campus Chapultepec, CP 11850, Mexico.
Departamento de Infectómica y Patogénesis Molecular, CINVESTAV-IPN, CP 07300, Mexico.
Microbiology (Reading). 2011 May;157(Pt 5):1489-1499. doi: 10.1099/mic.0.047183-0. Epub 2011 Feb 24.
Entamoeba histolytica trophozoites can induce host cell apoptosis, which correlates with the virulence of the parasite. This phenomenon has been seen during the resolution of an inflammatory response and the survival of the parasites. Other studies have shown that E. histolytica trophozoites undergo programmed cell death (PCD) in vitro, but how this process occurs within the mammalian host cell remains unclear. Here, we studied the PCD of E. histolytica trophozoites as part of an in vivo event related to the inflammatory reaction and the host-parasite interaction. Morphological study of amoebic liver abscesses showed only a few E. histolytica trophozoites with peroxidase-positive nuclei identified by terminal deoxynucleotidyltransferase enzyme-mediated dUTP nick end labelling (TUNEL). To better understand PCD following the interaction between amoebae and inflammatory cells, we designed a novel in vivo model using a dialysis bag containing E. histolytica trophozoites, which was surgically placed inside the peritoneal cavity of a hamster and left to interact with the host's exudate components. Amoebae collected from bags were then examined by TUNEL assay, fluorescence-activated cell sorting (FACS) and transmission electron microscopy. Nuclear condensation and DNA fragmentation of E. histolytica trophozoites were observed after exposure to peritoneal exudates, which were mainly composed of neutrophils and macrophages. Our results suggest that production of nitric oxide by inflammatory cells could be involved in PCD of trophozoites. In this modified in vivo system, PCD appears to play a prominent role in the host-parasite interaction and parasite cell death.
溶组织内阿米巴滋养体可以诱导宿主细胞凋亡，这与寄生虫的毒力有关。这种现象在炎症反应的解决和寄生虫的存活中都有观察到。其他研究表明，溶组织内阿米巴滋养体在体外经历程序性细胞死亡（PCD），但这个过程在哺乳动物宿主细胞内是如何发生的尚不清楚。在这里，我们研究了溶组织内阿米巴滋养体的 PCD，作为与炎症反应和宿主-寄生虫相互作用有关的体内事件的一部分。肝阿米巴脓肿的形态学研究显示，只有少数溶组织内阿米巴滋养体具有过氧化物酶阳性核，这些核通过末端脱氧核苷酸转移酶介导的 dUTP 缺口末端标记（TUNEL）鉴定。为了更好地理解在阿米巴与炎症细胞相互作用后发生的 PCD，我们设计了一种新的体内模型，使用含有溶组织内阿米巴滋养体的透析袋，将其手术放置在仓鼠的腹腔内，并让其与宿主渗出物成分相互作用。然后通过 TUNEL 测定、荧光激活细胞分选（FACS）和透射电子显微镜检查从袋子中收集的阿米巴。暴露于腹腔渗出物后，观察到溶组织内阿米巴滋养体的核浓缩和 DNA 片段化，这些渗出物主要由中性粒细胞和巨噬细胞组成。我们的结果表明，炎症细胞产生的一氧化氮可能参与了滋养体的 PCD。在这个改良的体内系统中，PCD 似乎在宿主-寄生虫相互作用和寄生虫细胞死亡中起着重要作用。
