Telmisartan inhibits both oxidative stress and renal fibrosis after unilateral ureteral obstruction in acatalasemic mice.

BACKGROUND: Reactive oxygen species are involved in many of the angiotensin II signalling pathways. We have thus investigated whether the angiotensin II type 1 (AT1) receptor antagonist, telmisartan, can inhibit the accelerated renal fibrosis and excess oxidative stress, which occurs after unilateral ureteral obstruction (UUO) in acatalasemic mice.
METHODS: The effect of daily intraperitoneal injection of telmisartan (0.1-0.3 mg/kg body weight) on the renal tubulointerstitial injury induced by UUO has been studied in homozygous acatalasemic mutant mice (C3H/AnLCs b Cs b) and wild-type mice (C3H/AnLCs a Cs a). We evaluated the systemic blood pressure of the mice on the seventh day. In addition, the tubulointerstitial expression of collagens type I and type IV, the p22-, p47- and p67-phox subunits of NADPH oxidase, 4-hydroxy-2-nonenal, and 4-hydroxy-2-hexenal lipid peroxidation products were assessed by immunohistochemistry. The level of apoptosis was determined by terminal deoxynucleotidyl transferase nick end-labelling analysis, while the mRNA level of the p22-, p47- and p67-phox subunits was quantified by real-time PCR. The renal content of each of the antioxidant enzymes catalase, glutathione peroxidase and superoxide dismutase was determined by specific assay.
RESULTS: Obstructed kidneys from acatalasemic mice exhibited increased tubulointerstitial deposition in dilated tubules of collagens type I and IV, lipid peroxidation products, and the p22/p47/p67-phox subunits of NADPH oxidase. The level of the p22/p47/p67-phox subunit mRNA, and of apoptosis in tubular epithelial cells, was also increased compared with those from wild-type kidneys. Treatment with telmisartan attenuated all of the changes and prevented renal fibrosis in a dose-dependent manner; despite the low dose (0.1 mg/kg). The treatment did not lower the systemic blood pressure. The catalase activity remained low in acatalasemic obstructed kidneys without compensatory upregulation of glutathione peroxidase or superoxide dismutase activity; the level of neither anti-oxidant enzymes in obstructed kidneys was affected by telmisartan.
CONCLUSIONS: The AT1 receptor antagonist telmisartan ameliorated renal fibrosis after UUO by inhibition of oxidative stress, even under acatalasemic conditions.