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Diabetes-induced oxidative stress is mediated by Ca2+-independent phospholipase A2 in neutrophils.
- Source :
-
Journal of immunology (Baltimore, Md. : 1950) [J Immunol] 2010 Feb 01; Vol. 184 (3), pp. 1507-15. Date of Electronic Publication: 2010 Jan 06. - Publication Year :
- 2010
-
Abstract
- Neutrophils from people with poorly controlled diabetes present a primed phenotype and secrete excessive superoxide. Phospholipase A(2) (PLA(2))-derived arachidonic acid (AA) activates the assembly of NADPH oxidase to generate superoxide anion. There is a gap in the current literature regarding which PLA(2) isoform regulates NADPH oxidase activation. The aim of this study was to identify the PLA(2) isoform involved in the regulation of superoxide generation in neutrophils and investigate if PLA(2) mediates priming in response to pathologic hyperglycemia. Neutrophils were isolated from people with diabetes mellitus and healthy controls, and HL60 neutrophil-like cells were grown in hyperglycemic conditions. Incubating neutrophils with the Ca(2+)-independent PLA(2) (iPLA(2)) inhibitor bromoenol lactone (BEL) completely suppressed fMLP-induced generation of superoxide. The nonspecific actions of BEL on phosphatidic acid phosphohydrolase-1, p47(phox) phosphorylation, and apoptosis were ruled out by specific assays. Small interfering RNA knockdown of iPLA(2) inhibited superoxide generation by neutrophils. Neutrophils from people with poorly controlled diabetes and in vitro incubation of neutrophils with high glucose and the receptor for advanced glycation end products ligand S100B greatly enhanced superoxide generation compared with controls, and this was significantly inhibited by BEL. A modified iPLA(2) assay, Western blotting, and PCR confirmed that there was increased iPLA(2) activity and expression in neutrophils from people with diabetes. AA (10 microM) partly rescued the inhibition of superoxide generation mediated by BEL, confirming that NADPH oxidase activity is, in part, regulated by AA. This study provides evidence for the role of iPLA(2) in enhanced superoxide generation in neutrophils from people with diabetes mellitus and presents an alternate pathway independent of protein kinase C and phosphatidic acid phosphohydrolase-1 hydrolase signaling.
- Subjects :
- Adult
Calcium physiology
Diabetes Mellitus, Type 1 enzymology
Diabetes Mellitus, Type 2 enzymology
Female
Gene Targeting
Group VI Phospholipases A2 antagonists & inhibitors
Group VI Phospholipases A2 genetics
Group VI Phospholipases A2 physiology
HL-60 Cells
Humans
Male
Middle Aged
Neutrophils immunology
Phosphatidate Phosphatase physiology
Protein Kinase C physiology
Signal Transduction genetics
Signal Transduction immunology
Superoxides blood
Up-Regulation immunology
Calcium blood
Diabetes Mellitus, Type 1 immunology
Diabetes Mellitus, Type 1 metabolism
Diabetes Mellitus, Type 2 immunology
Diabetes Mellitus, Type 2 metabolism
Group VI Phospholipases A2 blood
Neutrophils enzymology
Oxidative Stress immunology
Subjects
Details
- Language :
- English
- ISSN :
- 1550-6606
- Volume :
- 184
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- Journal of immunology (Baltimore, Md. : 1950)
- Publication Type :
- Academic Journal
- Accession number :
- 20053941
- Full Text :
- https://doi.org/10.4049/jimmunol.0901219