Chronic inhibition of NOS-2 ameliorates renal injury, as well as COX-2 and TGF-beta 1 overexpression in 5/6 nephrectomized rats.
BACKGROUND
Chronic renal damage is associated with inflammatory infiltration, fibrosis and vascular lesion, coupled with increased expression of cyclo-oxygenase 2 (COX-2) and transforming growth factor-beta1 (TGF-beta1). However, the role of inducible nitric oxide synthase (NOS-2) is still controversial. Thus, we studied the contribution of NOS-2 to the expression levels of COX-2 and TGF-beta1, as well as the structural renal injury in rats with subtotal renal ablation (5/6 Nx).


METHODS
Four groups of rats were studied: sham, 5/6 Nx, 5/6 Nx+aminoguanidine (AG) and 5/6 NX+L-NIL (L-N6-iminoethyl-lysine). Systolic blood pressure (SBP), proteinuria and creatinine (Cr) clearance were measured. NOS-2, COX-2 and TGF-beta1 gene expression was determined by real-time reverse transcription-polymerase-chain reaction. Protein expression was evaluated by western blot and ELISA (TGF-beta1). Immunohistochemistry and morphometry were performed for NOS-2, microvascular thickening and fibrosis.


RESULTS
Systemic hypertension and marked proteinuria, increased expression of NOS-2, COX-2 and TGF-beta1, thickening of arteriolar wall and tubulointerstitial fibrosis were produced in 5/6 Nx rats. Chronic inhibition of NOS-2 did not prevent arterial hypertension or the fall in Cr clearance, but partially reduced proteinuria. Nevertheless, AG and L-NIL preserved arteriolar morphology and the administration of both selective inhibitors of inducible NOS (AG and L-NIL) prevented NOS-2 overexpression.


CONCLUSIONS
This study shows that NOS-2 was markedly enhanced in renal tissue of 5/6 Nx rats. Moreover, treatment with AG and L-NIL prevented the morpho-functional changes induced by subtotal renal ablation, despite persistence of systemic hypertension, suggesting that high concentrations of nitric oxide produced by NOS-2 could act as a positive modulator of the proinflammatory and profibrotic pathways involved in the progression of renal disease.
Bautista-García
Pablo
P
Department of Nephrology, Instituto Nacional de Cardiología Ignacio Chávez, Juan Badiano 1, 14080-Mexico City, Mexico.
Sánchez-Lozada
Laura Gabriela
LG
Cristóbal-García
Magdalena
M
Tapia
Edilia
E
Soto
Virgilia
V
Avila-Casado
Ma Carmen
MC
Márquez-Velasco
Ricardo
R
Bojalil
Rafael
R
Franco
Martha
M
Herrera-Acosta
Jaime
J
D000818:Animals; D051546:Cyclooxygenase 2 / Q000096:biosynthesis* / Q000235:genetics*; D007672:Kidney Cortex / Q000098:blood supply / Q000201:enzymology* / Q000378:metabolism / Q000473:pathology*; D008026:Ligation; D008297:Male; D009392:Nephrectomy; D009569:Nitric Oxide / Q000502:physiology; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012077:Renal Artery / Q000601:surgery; D053773:Transforming Growth Factor beta1 / Q000096:biosynthesis* / Q000235:genetics*
D053773:Transforming Growth Factor beta1; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D051546:Cyclooxygenase 2