Mitochondrial complex III in larval stage of Echinococcus multilocularis as a potential chemotherapeutic target and in vivo efficacy of atovaquone against primary hydatid cysts
Mitochondrial complex III in larval stage of Echinococcus multilocularis as a potential chemotherapeutic target and in vivo efficacy of atovaquone against primary hydatid cysts
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DOI：
10.1016/j.parint.2019.102004
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发表时间：
2020-04-01
影响因子：
1.9
通讯作者：
Kita, Kiyoshi
中科院分区：
文献类型：
--
作者：
Enkai, Shigehiro;Inaoka, Daniel Ken;Kita, Kiyoshi
多房棘球绦虫通过需氧和无氧呼吸途径在宿主的特殊环境中生存。在厌氧条件下，富马酸的呼吸已被确定为一个有希望的药物开发目标，以对抗多房埃希氏菌幼虫，尽管氧化磷酸化与其存活的相关性尚不清楚。在这里，我们专注于对线粒体细胞色素Bc1复合体(复合体III)的抑制，并使用多房原头节线粒体组分来评估有氧呼吸活性。酶活性测定表明，线粒体部分在有氧途径中具有NADH-细胞色素C还原酶(线粒体复合体I和III)和琥珀酸细胞色素C还原酶(线粒体复合体II和III)的活性。酶分析表明，市售抗疟药阿托瓦酮对线粒体复合体III在1.5 nm处有抑制作用(IC50)。此外，培养实验表明，阿托瓦酮在好氧条件下能够杀死原头节，但在厌氧条件下不能，这表明原头节的呼吸系统根据氧气供应的不同而改变为氧化磷酸化或富马酸呼吸系统。此外，阿托瓦酮和阿片菌素A5(一种化合物II的醌结合部位抑制剂)联合使用，完全杀死了培养物中的原头节。因此，抑制复合体II和复合体III对多房拟青霉具有较强的抗寄生性是必不可少的。此外，我们还证明，与未经治疗的对照组相比，口服阿托瓦酮显著减少了小鼠肝脏原发泡状棘球蚴的发育，表明复合体III是开发抗包虫病药物的一个有前途的靶点。
Echinococcus multilocularis employs aerobic and anaerobic respiration pathways for its survival in the specialized environment of the host. Under anaerobic conditions, fumarate respiration has been identified as a promising target for drug development against E. multilocularis larvae, although the relevance of oxidative phosphorylation in its survival remains unclear. Here, we focused on the inhibition of mitochondrial cytochrome bc1 complex (complex III) and evaluated aerobic respiratory activity using mitochondrial fractions from E. multilocularis protoscoleces. An enzymatic assay revealed that the mitochondrial fractions possessed NADH-cytochrome c reductase (mitochondrial complexes I and III) and succinate-cytochrome c reductase (mitochondrial complexes II and III) activities in the aerobic pathway. Enzymatic analysis showed that atovaquone, a commercially available anti-malarial drug, inhibited mitochondrial complex III at 1.5 nM (IC50). In addition, culture experiments revealed the ability of atovaquone to kill protoscoleces under aerobic conditions, but not under anaerobic conditions, indicating that protoscoleces altered their respiration system to oxidative phosphorylation or fumarate respiration depending on the oxygen supply. Furthermore, combined administration of atovaquone with atpenin A5, a quinone binding site inhibitor of complex II, completely killed protoscoleces in the culture. Thus, inhibition of both complex II and complex III was essential for strong antiparasitic effect on E. multilocularis. Additionally, we demonstrated that oral administration of atovaquone significantly reduced primary alveolar hydatid cyst development in the mouse liver, compared with the untreated control, indicating that complex III is a promising target for development of anti-echinococcal drug.