Aliskiren reduces home blood pressure and albuminuria in patients with hypertensive nephrosclerosis

Arterial wall hypertrophy is ameliorated by α2-adrenergic receptor antagonist or aliskiren in kidneys of angiotensinogen-knockout mice

BACKGROUND

Arterial hypertrophy and interstitial fibrosis are important characteristics in kidneys of angiotensinogen-knockout (Atg ^-/-) mice. In these mice, which exhibit polyuria and hypotension, sympathetic nerve signaling is estimated to be compensatorily hyperactive. Furthermore, transforming growth factor (TGF)-β1 is overexpressed in mice kidneys. To determine whether sympathetic nerve signaling and TGF-β1 exacerbate arterial hypertrophy and interstitial fibrosis, intervention studies of such signaling are required.

METHODS

We performed renal denervation and administered the α2-adrenergic receptor (AR) antagonist, atipamezole, to Atg ^-/- mice. A renin inhibitor, aliskiren, which was preliminarily confirmed to reduce TGF-β1 gene expression in kidneys of the mice, was additionally administered to assess the effect on the arterial hypertrophy and interstitial fibrosis.

RESULTS

Norepinephrine content in kidneys of Atg ^-/- mice was three times higher than in kidneys of wild-type mice. Interventions by renal denervation and atipamezole resulted in amelioration of the histological findings. Overexpression of TGF-β1 gene in kidneys of Atg ^-/- mice was altered in a manner linked to the histological findings. Surprisingly, aliskiren reduced α2-AR gene expression, interstitial fibrosis, and arterial hypertrophy in kidneys of Atg ^-/- mice, which lack renin substrate.

CONCLUSIONS

Alpha2-AR signaling is one of the causes of persistent renal arterial hypertrophy in Atg ^-/- mice. Aliskiren also angiotensinogen-independently reduces the extent of renal arterial hypertrophy, partly thorough downregulation of α2-ARs. Although renal arterial hypertrophy in Atg ^-/- mice appears to be of multifactorial origin, TGF-β1 may play a key role in the persistence of such hypertrophy.

Differing Effects of Aliskiren/Amlodipine Combination and High-Dose Amlodipine Monotherapy on Ambulatory Blood Pressure and Target Organ Protection

The aim of this study was to compare an aliskiren/amlodipine combination with high-dose amlodipine monotherapy on ambulatory blood pressure monitoring (ABPM) and organ protection. The study was a prospective, randomized, multicenter, open-label trial in elderly essential hypertensive patients. A total of 105 patients with clinic BP (CBP) ≥140/90 mm Hg with amlodipine 5 mg were randomly allocated to aliskiren (150-300 mg)/amlodipine (5 mg) (ALI/AML group, n=53) or high-dose amlodipine (10 mg) (h-dAML group, n=52) and treated for 16 weeks. Each patient's CBP, ABPM, urine albumin-to-creatinine ratio (UACR), and brachial-ankle pulse wave velocity (baPWV) were measured at baseline and at the end of the study. The ALI/AML and h-dAML groups showed similarly reduced mean 24-hour SBP, daytime SBP, nighttime SBP, and baPWV. However, UACR reduction was significantly greater in the ALI/AML group (P=.02). ALI/AML was significantly less effective in reducing early-morning BP (P=.002) and morning BP surge (P=.001) compared with h-dAML.

Renin inhibition ameliorates renal damage through prominent suppression of both angiotensin I and II in human renin angiotensinogen transgenic mice with high salt loading

BACKGROUND

The renin-angiotensin-aldosterone system (RAAS) plays pivotal roles in the pathogenesis of chronic kidney disease (CKD) progression. Aliskiren, a direct renin inhibitor, inhibits the rate-limiting step of the RAAS without any alternative pathway. It is proven to reduce albuminuria in CKD patients treated with angiotensin blockade. However, there are few reports which evaluate the advantage of aliskiren as the first-line drug against CKD progression in RAAS-activated hypertensive patients.

METHODS

Tsukuba hypertensive mice (THM), double transgenic mice carrying both the human renin and human angiotensinogen genes, were fed a high-salt diet and treated with hydraladine, ramipril and aliskiren for 10 weeks. Blood pressure and urinary albumin excretion were measured every 2 weeks during the experimental period. We evaluated renal histological changes and gene expression. Plasma angiotensin concentration was measured to evaluate the RAAS inhibitory effect.

RESULTS

High-salt-loaded THM showed severe hypertension and renal injury. All antihypertensive drugs suppressed blood pressure and prevented renal disease progression. RAAS blockade showed a higher renoprotective effect than hydraladine despite an equivalent blood pressure lowering effect. Aliskiren exhibited even stronger renoprotection than ramipril. Plasma angiotensin concentration was increased in THM fed both normal salt and high salt. Hydraladine did not alter the plasma angiotensin concentration. Ramipril significantly decreased angiotensin II concentration. Aliskiren treatment almost completely suppressed angiotensin I and resulted in lower angiotensin II concentration than ramipril treatment.

CONCLUSION

Aliskiren prevents renal disease progression by suppressing both angiotensin I and II in RAAS-activated pathology. Our data suggest the application of a renin inhibitor for preventing kidney disease progression in CKD patients.