Issam Harfi1,2, Stéphanie D'Hondt3, Eric Sariban3,4. 1. Pediatric Oncology Laboratory, Hôpital Universitaire des Enfants, 1020, Brussels, Belgium. Issam.harfi@huderf.be. 2. Cancer Unit, Hôpital Universitaire des Enfants, 15, Avenue Jean-Joseph Crocq, 1020, Brussels, Belgium. Issam.harfi@huderf.be. 3. Pediatric Oncology Laboratory, Hôpital Universitaire des Enfants, 1020, Brussels, Belgium. 4. Cancer Unit, Hôpital Universitaire des Enfants, 15, Avenue Jean-Joseph Crocq, 1020, Brussels, Belgium.
Abstract
PURPOSE: 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. METHODS: 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. RESULTS: W7 increases exocytosis of primary, secondary, and tertiary granules and vesicles and improves neutrophil microbicidal activity against S. aureus and A. fumigatus. CONCLUSIONS: 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.
PURPOSE: 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. METHODS: 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. RESULTS: W7 increases exocytosis of primary, secondary, and tertiary granules and vesicles and improves neutrophil microbicidal activity against S. aureus and A. fumigatus. CONCLUSIONS: 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 CGDpatients presenting ROS defective production, this increase in the non-oxidative killing pathway partially corrects their microbicidal defects.
Authors: Neelakshi R Jog; Madhavi J Rane; George Lominadze; Gregory C Luerman; Richard A Ward; Kenneth R McLeish Journal: Am J Physiol Cell Physiol Date: 2007-01-03 Impact factor: 4.249
Authors: Sandra Verploegen; Caroline M van Leeuwen; Hanneke W M van Deutekom; Jan-Willem J Lammers; Leo Koenderman; Paul J Coffer Journal: Eur J Biochem Date: 2002-09