Pediatric Oncology Laboratory, Hôpital Universitaire des Enfants, 1020, Brussels, Belgium.
Cancer Unit, Hôpital Universitaire des Enfants, 15, Avenue Jean-Joseph Crocq, 1020, Brussels, Belgium.
J Clin Immunol. 2019 Jul;39(5):486-493. doi: 10.1007/s10875-019-00630-7. Epub 2019 Jun 1.
The ubiquitous calcium-independent phospholipase A2 enzyme (iPLA2) is inhibited by calmodulin binding and known to be responsible for phospholipid remodeling housekeeping functions including granule exocytosis-associated membrane fusion in normal human neutrophils. We evaluate in human neutrophils the iPLA2 secretagogue effects using normal neutrophils, where reactive oxygen species (ROS) generation has been blocked by diphenyleneiodonium, as well as in neutrophils from chronic granulomatous disease (CGD) patients.
Neutrophils were pretreated with W7, a calmodulin inhibitor known to activate iPLA2 and exocytosis of granules, and vesicles as well as intra- and extra-microbicidal activity against Staphylococcus aureus and Aspergillus fumigatus were evaluated.
W7 increases exocytosis of primary, secondary, and tertiary granules and vesicles and improves neutrophil microbicidal activity against S. aureus and A. fumigatus.
In neutrophils, calmodulin-mediated iPLA2 inhibition controls granule and vesicle exocytosis in the phagosome and in the extracellular microenvironment. Relieving iPLA2 inhibition results in increased exocytosis of primary, secondary, and tertiary granules and secretory vesicles with correction of defective intracellular and extracellular microbicidal activity. In CGD patients presenting ROS defective production, this increase in the non-oxidative killing pathway partially corrects their microbicidal defects.
普遍存在的钙非依赖性磷脂酶 A2 酶（iPLA2）通过钙调蛋白结合而被抑制，已知其负责磷脂重排等管家功能，包括正常人类中性粒细胞中颗粒胞吐相关的膜融合。我们在人类中性粒细胞中评估了 iPLA2 分泌激动剂的作用，使用了活性氧（ROS）生成已被二苯乙烯碘抑制的正常中性粒细胞，以及慢性肉芽肿病（CGD）患者的中性粒细胞。
用钙调蛋白抑制剂 W7 预处理中性粒细胞，W7 已知可激活 iPLA2 并促进颗粒和小泡的胞吐作用，以及对金黄色葡萄球菌和烟曲霉的细胞内和细胞外杀菌活性。
W7 增加了初级、次级和三级颗粒以及小泡的胞吐作用，并提高了中性粒细胞对金黄色葡萄球菌和烟曲霉的杀菌活性。
在中性粒细胞中，钙调蛋白介导的 iPLA2 抑制控制着吞噬体和细胞外微环境中颗粒和小泡的胞吐作用。解除 iPLA2 抑制导致初级、次级和三级颗粒和分泌小泡的胞吐作用增加，同时纠正了细胞内和细胞外杀菌活性的缺陷。在 ROS 产生缺陷的 CGD 患者中，这种非氧化杀伤途径的增加部分纠正了他们的杀菌缺陷。
