Spironolactone Ameliorates Angiotensin Ii-Induced Renal Damage Via the Inhibition of Ap-1 and Nf-κB
Recently, clinical trials have demonstrated the efficacy of spironolactone (SPIRO) in men. Nevertheless the molecular mechanism of action not completely understood. Locally generated angiotensin II (ANG II) stimulates aldosterone. Therefore, we have tested the hypothesis that SPIRO ameliorates ANG II-induced renal damage. Furthermore, we investigated the effect of SPIRO on the transcription factors AP-1 and NF-κB. We treated transgenic rats overexpressing the human renin and angiotensinogen genes (dTGR) from week 5 to 7 with SPIRO (20 mg/kg/d). Plasma aldosterone was significantly increased in dTGR vs. SPIRO treated and non-transgenic (SD) rats (p<0.05). Untreated dTGR showed high systolic blood pressure (182±8 mm Hg), severe renal damage with 150-fold increased albuminuria, vasculopathy and perivascular and interstitial fibrosis. Chronic SPIRO treatment reduced mortality and vasculopathy completely, despite blood pressure levels of 161±11. 24-hour albuminuria was reduced from 59±15 in dTGR to 3.5±2 mg/d; p<0.01). Electrophoretic mobility gel shift analysis demonstrated a reduction of renal AP-1 and NF-κB DNA binding activity after SPIRO treatment. Immunohistological analysis showed that SPIRO also prevented the expression of AP-1 and/or NF-kB regulated matrix molecules fibronectin and laminin. The reno-protective effect of SPIRO was accompanied with a reduction of monocyte/macrophage infiltration. These findings show that blockade of aldosterone signaling ameliorates ANG II-induced renal damage. SPIRO action was at least partially mediated via AP-1 and NF-κB.