title: A dual role for diacylglycerol kinase generated phosphatidic acid in autoantibody-induced neutrophil exocytosis.
abstract: Dysregulated release of neutrophil azurophilic granules causes increased tissue damage and amplified inflammation during autoimmune disease. Antineutrophil cytoplasmic antibodies (ANCAs) are implicated in the pathogenesis of small vessel vasculitis and promote adhesion and exocytosis in neutrophils. ANCAs activate specific signal transduction pathways in neutrophils that have the potential to be modulated therapeutically to prevent neutrophil activation by ANCAs. We have investigated a role for diacylglycerol kinase (DGK) and its downstream product phosphatidic acid (PA) in ANCA-induced neutrophil exocytosis. Neutrophils incubated with the DGK inhibitor R59022, before treatment with ANCAs, exhibited a reduced capacity to release their azurophilic granules, demonstrated by a component release assay and flow cytometry. PA restored azurophilic granule release in DGK-inhibited neutrophils. Confocal microscopy revealed that R59022 did not inhibit translocation of granules, indicating a role for DGK during the process of granule fusion at the plasma membrane. In investigating possible mechanisms by which PA promotes neutrophil exocytosis, we demonstrated that exocytosis can only be restored in R59022-treated cells through simultaneous modulation of membrane fusion and increasing cytosolic calcium. PA and its associated pathways may represent viable drug targets to reduce tissue injury associated with ANCA-associated vasculitic diseases and other neutrophilic inflammatory disorders.
authors.affiliation: Renal Immunobiology, School of Immunity and Infection, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Neil J
authors.initials: NJ
authors.lastname: Holden
authors.forename: Caroline O S
authors.initials: CO
authors.lastname: Savage
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Young
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Wakelam
authors.forename: Lorraine
authors.initials: L
authors.lastname: Harper
authors.forename: Julie M
authors.initials: JM
authors.lastname: Williams
mesh_terms: D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000276:immunology*; D002118:Calcium / Q000378:metabolism; D003594:Cytoplasmic Granules / Q000187:drug effects / Q000378:metabolism; D019852:Diacylglycerol Kinase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D005089:Exocytosis / Q000276:immunology*; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D015759:Ionomycin / Q000494:pharmacology; D008244:Lysophosphatidylcholines / Q000378:metabolism / Q000494:pharmacology; D008561:Membrane Fusion / Q000187:drug effects; D009504:Neutrophils / Q000166:cytology* / Q000201:enzymology* / Q000276:immunology; D009195:Peroxidase / Q000378:metabolism; D010712:Phosphatidic Acids / Q000096:biosynthesis*; D011744:Pyrimidinones / Q000494:pharmacology; D060149:Tetraspanin 30 / Q000378:metabolism; D013844:Thiazoles / Q000494:pharmacology
chemical_list: D000199:Actins; D019268:Antibodies, Antineutrophil Cytoplasmic; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D008244:Lysophosphatidylcholines; D010712:Phosphatidic Acids; D011744:Pyrimidinones; D060149:Tetraspanin 30; D013844:Thiazoles; D015759:Ionomycin; C047505:R 59022; D009195:Peroxidase; D019852:Diacylglycerol Kinase; D002118:Calcium