Leishmania major Promastigotes Evade LC3-Associated Phagocytosis through the Action of GP63.
Leishmania major Promastigotes Evade LC3-Associated Phagocytosis through the Action of GP63.
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DOI：
10.1371/journal.ppat.1005690
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发表时间：
2016-06
期刊：
影响因子：
6.7
通讯作者：
Descoteaux A
中科院分区：
文献类型：
--
作者：
Matte C;Casgrain PA;Séguin O;Moradin N;Hong WJ;Descoteaux A
原生动物利什曼原虫寄生于巨噬细胞，通过抑制吞噬溶酶体的生物发生来逃避吞噬作用的杀微生物后果。在这项研究中，我们研究了这种寄生虫对LC 3相关吞噬作用的影响，这是一种增强吞噬体成熟和功能的非经典自噬过程。我们发现，虽然内化的L。巨噬细胞的主要前鞭毛体促进LC 3脂化，通过寄生虫表面金属蛋白酶GP 63的作用抑制LC 3向吞噬体的募集。由NOX 2 NADPH氧化酶产生的活性氧是LC 3相关吞噬作用所必需的。我们发现L.主要前鞭毛体以GP 63依赖性方式阻止了通过不涉及NOX 2切割的机制将NOX 2募集到吞噬体。此外，我们发现，SNARE蛋白VAMP 8，调节吞噬体组装的NADPH氧化酶NOX 2，下调GP 63。在不存在VAMP 8的情况下，LC 3向含有GP 63缺陷型寄生虫的吞噬体的募集被抑制，表明VAMP 8参与LC 3的吞噬体募集。这些发现揭示了VAMP 8在LC 3相关吞噬作用中的作用，并强调了L.主要的前鞭毛体干扰宿主的抗菌机制。围绕病原体的吞噬作用和随后的早期事件在很大程度上决定了内化是否会导致微生物的有效杀死或细胞内感染的成功建立。越来越多的证据支持这样一种观点，即自噬机制有助于吞噬作用消除细胞内病原体，这一过程称为LC 3相关吞噬作用（LC 3-associated phagocytosis，LC 3-associated phagocytosis）。利什曼原虫属的原生动物寄生虫使用表面毒力因子如脂磷酸聚糖和金属蛋白酶GP 63来干扰吞噬溶酶体生物合成并破坏巨噬细胞抗微生物功能。在这里，我们提供了第一个证据，L。主要的前鞭毛体以GP 63依赖的方式逃避哺乳动物，并揭示了膜融合介体VAMP 8在哺乳动物中的新作用。我们的研究结果提供了一个更好的理解利什曼原虫的发病机制和背后的机制。
The protozoan Leishmania parasitizes macrophages and evades the microbicidal consequences of phagocytosis through the inhibition of phagolysosome biogenesis. In this study, we investigated the impact of this parasite on LC3-associated phagocytosis, a non-canonical autophagic process that enhances phagosome maturation and functions. We show that whereas internalization of L. major promastigotes by macrophages promoted LC3 lipidation, recruitment of LC3 to phagosomes was inhibited through the action of the parasite surface metalloprotease GP63. Reactive oxygen species generated by the NOX2 NADPH oxidase are necessary for LC3-associated phagocytosis. We found that L. major promastigotes prevented, in a GP63-dependent manner, the recruitment of NOX2 to phagosomes through a mechanism that does not involve NOX2 cleavage. Moreover, we found that the SNARE protein VAMP8, which regulates phagosomal assembly of the NADPH oxidase NOX2, was down-modulated by GP63. In the absence of VAMP8, recruitment of LC3 to phagosomes containing GP63-deficient parasites was inhibited, indicating that VAMP8 is involved in the phagosomal recruitment of LC3. These findings reveal a role for VAMP8 in LC3-associated phagocytosis and highlight a novel mechanism exploited by L. major promastigotes to interfere with the host antimicrobial machinery. The early events surrounding and following the phagocytosis of pathogens largely determine whether internalization will lead to efficient killing of the microbe or successful establishment of an intracellular infection. Growing evidence supports the notion that the autophagy machinery lends a hand to phagocytosis in eliminating intracellular pathogens, in a process known as LC3-associated phagocytosis (LAP). Protozoan parasites of the Leishmania genus use surface virulence factors such as lipophosphoglycan and the metalloprotease GP63 to interfere with phagolysosome biogenesis and sabotage macrophage antimicrobial functions. Here, we provide the first evidence that L. major promastigotes evade LAP in a GP63-dependent manner and uncover a novel role for the membrane fusion mediator VAMP8 in LAP. Our findings offer a better understanding of Leishmania pathogenesis and of the mechanism behind LAP.