Increased 5-lipoxygenase activating protein in immune-mediated experimental nephritis.
BACKGROUND
The binding of 5-lipoxygenase (5-LO) to 5-LO activating protein (FLAP) is a prerequisite for subsequent formation of leukotrienes from arachidonic acid.


METHODS
We investigated the localization of FLAP in a rat model of accelerated anti-glomerular basement membrane nephritis and protein expression in cultured rat glomerular endothelial cells.


RESULTS
As expected, 5-LO staining was intense and localized exclusively to perinuclear region and inside the nucleus of leukocytes and macrophages. In these cells, FLAP immunoreactivity co-localized with that of 5-LO, and was restricted to nuclear envelope. Surprisingly, intense nuclear and cytoplasmic staining for FLAP was also observed in glomerular endothelial cells in early experimental glomerulonephritis. Although 5-LO and FLAP mRNA were detected in cultured rat glomerular endothelial cells by RT-PCR, Western blot revealed only FLAP and no 5-LO protein. FLAP protein was regulated in glomerular endothelial cells by the proinflammatory cytokine, interferon-gamma, in a dose-dependent manner.


CONCLUSIONS
The unexpected discovery of FLAP in glomerular endothelial cells in this model of glomerulonephritis, coupled with our demonstration that oral FLAP antagonist therapy reduces proteinuria in human glomerulonephritis and animal models of diabetes, provides further impetus to examine the role of this pro-inflammatory protein in glomerular immune injury.
Montero
Angel
A
Renal Division, Emory University School of Medicine, Atlanta, USA.
Uda
Susumu
S
Kelavkar
Uddhav
U
Yoshimura
Ashio
A
Badr
Kamal F
KF
Munger
Karen A
KA
D058927:5-Lipoxygenase-Activating Proteins; D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism; D001485:Basement Membrane / Q000276:immunology; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D004727:Endothelium / Q000201:enzymology; D004789:Enzyme Activation; D005921:Glomerulonephritis / Q000201:enzymology* / Q000276:immunology / Q000473:pathology; D007114:Immunization; D007150:Immunohistochemistry; D018836:Inflammation Mediators / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology; D007678:Kidney Glomerulus / Q000201:enzymology* / Q000276:immunology / Q000473:pathology; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D016253:Microscopy, Immunoelectron; D051381:Rats; D017207:Rats, Sprague-Dawley
D058927:5-Lipoxygenase-Activating Proteins; C548592:ALOX5AP protein, human; C548594:Alox5ap protein, rat; D002352:Carrier Proteins; D018836:Inflammation Mediators; D008565:Membrane Proteins; D007371:Interferon-gamma; D001094:Arachidonate 5-Lipoxygenase