Laboratory of Microbiology, Parasitology and Hygiene (LMPH), Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, Antwerp University, Wilrijk, Belgium.
Parasitology. 2012 Sep;139(11):1429-37. doi: 10.1017/S003118201200073X. Epub 2012 Jul 10.
Leishmania parasites are able to survive in the macrophage, one of the most hostile environments of the vertebrate host. The present study investigated how Leishmania infection influences these host cell defence mechanisms. Macrophages were infected with antimony-susceptible and -resistant Leishmania strains. Free radical production in Leishmania-infected macrophages was measured by electron paramagnetic resonance. Apoptosis was detected with fluorescence microscopy using Annexin-V FITC labelling and with Western blotting to detect caspase-3 cleavage. Independent of their drug susceptibility profile or species background, all studied Leishmania strains induced a similar increase in free radical production in macrophages. O2 ●- production was significantly elevated during phagocytosis of the stationary phase promastigotes. Conversely, NO levels increased later in the infection and none of the strains induced capsase-3 cleavage. Leishmania donovani infection led to phosphatidylserine externalization only in RAW 264.7 cells. After an initial burst of O2 ●- during phagocytosis of promastigotes, amastigotes protect themselves by decreasing the O2 ●- production to the basal level. An increased NO production was observed 6 h after infection. Finally, induction of cell death is probably not essential in the survival of the parasite within the macrophage.
利什曼原虫寄生虫能够在巨噬细胞中存活，巨噬细胞是脊椎动物宿主中最具敌意的环境之一。本研究探讨了利什曼原虫感染如何影响这些宿主细胞防御机制。用电子顺磁共振测量了感染了锑敏感和耐药利什曼原虫株的巨噬细胞中的自由基产生。用荧光显微镜用 Annexin-V FITC 标记和用 Western blot 检测 caspase-3 切割来检测细胞凋亡。无论其药物敏感性谱或物种背景如何，所有研究的利什曼原虫株都在巨噬细胞中诱导了类似的自由基产生增加。在吞噬静止期前鞭毛体时，O2●-的产生显著增加。相反，NO 水平在感染后期增加，没有一种菌株诱导 caspase-3 切割。杜氏利什曼原虫感染仅导致 RAW 264.7 细胞中的磷脂酰丝氨酸外翻。在前鞭毛体吞噬过程中 O2●-的初始爆发后，无鞭毛体通过将 O2●-的产生降低到基础水平来保护自己。感染 6 小时后观察到 NO 产量增加。最后，诱导细胞死亡可能不是寄生虫在巨噬细胞内存活所必需的。
