Effect of nitric oxide modulation on TGF-beta1 and matrix proteins in chronic cyclosporine nephrotoxicity.
BACKGROUND
Chronic cyclosporine (CsA) nephrotoxicity is characterized by interstitial fibrosis and afferent arteriolar hyalinosis. L-arginine (L-Arg), the substrate for nitric oxide (NO) synthase and N-nitro-L-arginine-methyl ester (L-NAME), the NO synthase inhibitor, were shown to modulate acute CsA nephrotoxicity. However, the mechanism of fibrosis in chronic CsA nephrotoxicity remains unclear. Thus, we examined the effect of NO modulation on fibrosis and the expression of transforming growth factor-beta1 (TGF-beta1) and matrix proteins in chronic CsA nephrotoxicity.


METHODS
Rats were administered CsA (7.5 mg/kg), CsA + L-Arg (1.7 g/kg), CsA + L-NAME (3.5 mg/kg), vehicle (VH), VH + L-Arg, and VH + L-NAME, and were sacrificed at 7 or 28 days. NO production, physiologic parameters, and histology were studied in addition to the mRNA expression of TGF-beta1, plasminogen activator inhibitor-1 (PAI-1) and the matrix proteins biglycan and collagens type I and IV by Northern and the protein expression of PAI-1 and fibronectin by enzyme-linked immunosorbent assay.


RESULTS
While L-NAME strikingly reduced NO biosynthesis and worsened the glomerular filtration rate and CsA-induced fibrosis, L-Arg had the opposite beneficial effect. In addition, the CsA-induced up-regulated expression of TGF-beta1, PAI-1, and the matrix proteins biglycan, fibronectin, and collagen I was significantly increased with L-NAME and strikingly improved with L-Arg. Collagen IV expression was not affected. Also, NO modulation did not affect VH-treated rats.


CONCLUSIONS
Chronic CsA nephrotoxicity can be aggravated by NO blockade and ameliorated by NO enhancement, suggesting that NO maintains a protective function. NO modulation was associated with a change in TGF-beta1 expression, which, in turn, was associated with alterations in matrix deposition and matrix degradation through its effect on PAI-1.
Shihab
F S
FS
Divisions of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah, USA. Fuad.Shihab@hsc.utah.edu
Yi
H
H
Bennett
W M
WM
Andoh
T F
TF
D000818:Animals; D001120:Arginine / Q000494:pharmacology; D001160:Arterioles / Q000378:metabolism / Q000473:pathology; D058578:Biglycan; D001794:Blood Pressure; D015152:Blotting, Northern; D002908:Chronic Disease; D003094:Collagen / Q000235:genetics / Q000378:metabolism; D016572:Cyclosporine / Q000633:toxicity*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016326:Extracellular Matrix Proteins / Q000235:genetics* / Q000378:metabolism; D005353:Fibronectins / Q000235:genetics / Q000378:metabolism; D005355:Fibrosis; D015870:Gene Expression / Q000187:drug effects; D005919:Glomerular Filtration Rate; D006818:Hyalin / Q000378:metabolism; D007166:Immunosuppressive Agents / Q000633:toxicity*; D007674:Kidney Diseases / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D007678:Kidney Glomerulus / Q000098:blood supply / Q000378:metabolism / Q000473:pathology; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000652:urine*; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics / Q000378:metabolism; D011509:Proteoglycans / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D016212:Transforming Growth Factor beta / Q000235:genetics* / Q000378:metabolism
D058578:Biglycan; D004791:Enzyme Inhibitors; D016326:Extracellular Matrix Proteins; D005353:Fibronectins; D007166:Immunosuppressive Agents; D017395:Plasminogen Activator Inhibitor 1; D011509:Proteoglycans; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D009569:Nitric Oxide; D016572:Cyclosporine; D003094:Collagen; D001120:Arginine; D019331:NG-Nitroarginine Methyl Ester