Aliskiren attenuates oxidative stress and improves tubular status in non-diabetic patients with chronic kidney disease-Placebo controlled, randomized, cross-over study

PURPOSE

Pharmacological inhibition of the renin-angiotensin-aldosteron system (RAAS) may have a beneficial impact on proteinuria and chronic kidney diseases (CKD) progression. Despite recent progress by means of angiotensin-converting enzyme inhibitors (ACEI) and angiotensin II receptor blockers (ARB), there is still no optimal therapy which can stop progression of the nephropathy. Recently introduced aliskiren is the first orally bioavailable direct renin inhibitor approved for the treatment of hypertension. The purpose was to evaluate the extent of oxidative stress and tubular injury after the direct renin inhibitor, aliskiren compared with placebo and perindopril in patients with non-diabetic chronic kidney disease (NDCKD).

MATERIAL/METHODS

A randomized, double-blind, cross-over trial was performed in 14 patients receiving 300mg aliskiren, 10mg perindopril and placebo in random order. The end point was a change in the urinary excretion of N-acetyl-β-D-glucosaminidase (NAG) and α1-microglobulin (α1m) and 15-F(2α)-isoprostane.

RESULTS

Aliskiren reduced excretion of 15-F(2α)-isoprostane (p=0.03) and α1m (p=0.01) as compared to placebo. There were no differences between aliskiren and perindopril in this regard. NAG urine excretion did not change after aliskiren and perindopril.

CONCLUSIONS

Aliskiren attenuates oxidative stress and may improve functional status of tubules in patients with NDCKD.

Direct renin inhibition in chronic kidney disease

For approximately 6 years, the only commercially available direct renin inhibitor, aliskiren, which inhibits the renin-angiotensin-aldosterone system at the initial rate limiting step, has been marketed for the treatment of hypertension. Concurrently, much attention has been given to the possibility that renin inhibition could hold potential for improved treatment in patients with chronic kidney disease, with diabetic nephropathy as an obvious group of patients to investigate, as the activity of the renin-angiotensin-aldosterone system is enhanced in these patients and as there is an unmet need for improved treatment and prognosis in these patients. Several short term studies have been performed in diabetic nephropathy, showing a consistent effect on the surrogate endpoint lowering of albuminuria, both as monotherapy and in combination with other blockers of the renin-angiotensin-aldosterone system. In addition, combination treatment also seemed safe and effective in patients with impaired kidney function. These initial findings formed the basis for the design of a large morbidity and mortality trial investigating aliskiren as add-on to standard treatment. The study has just concluded, but was terminated early as a beneficial effect was unlikely and there was an increased frequency of side effects. Also in non-diabetic kidney disease a few intervention studies have been carried out, but there is no ongoing hard outcome study. In this review we provide the current evidence for renin inhibition in chronic kidney disease by reporting the studies published so far as well as a perspective on the future possibilities.

Chronic kidney disease: a new look at pathogenetic mechanisms and treatment options

The concept of renoprotection has evolved significantly, driven by improved understanding of the pathophysiology of chronic kidney disease (CKD) and the advent of novel treatment options. Glomerular hyperfiltration, hypertension and proteinuria represent key mediators of CKD progression. It is increasingly recognized that proteinuria may actually be pathological and etiological in CKD progression and not just symptomatic. It initiates a sequence of events involving activation of proinflammatory and profibrotic signaling pathways in proximal tubular epithelial cells with transmission of the disease to the tubulointerstitium and progression to end-stage kidney disease (ESKD). Although the etiology and epidemiology of pediatric CKD differs to that in adults, studies in the various animal models of kidney disease, from obstructive uropathy to glomerulonephritis, have revealed that many common proinflammatory and profibrotic pathways are induced in progressive proteinuric CKD, irrespective of the primary disease. This pathomechanistic overlap therefore translates into the potential for common treatment targets for a wide spectrum of kidney diseases. In this review we therefore discuss the experimental and clinical evidence for an array of prospective future drug treatments of CKD progression. While conceptually promising, clear definitive evidence beyond preclinical data does not exist for many of these treatments, and others are limited by serious adverse effects. More studies are needed before general recommendations can be given.

Renoprotective effect of renal liver-type fatty acid binding protein and angiotensin II type 1a receptor loss in renal injury caused by RAS activation

The aim of this study was to assess the renoprotective effect of renal human liver-type fatty acid binding protein (hL-FABP) and angiotensin II (ANG II) type 1A receptor (AT1a) loss in renal injury caused by renin-angiotensin system (RAS) activation. We established hL-FABP chromosomal transgenic mice (L-FABP+/−AT1a+/+), crossed the L-FABP+/−AT1a+/+ with AT1a knockdown homo mice (L-FABP−/−AT1a−/−), and generated L-FABP+/−AT1a hetero mice (L-FABP+/−AT1a+/−). After the back-cross of these cubs, L-FABP+/−AT1a−/− were obtained. To activate the renal RAS, wild-type mice (L-FABP−/−AT1a+/+), L-FABP+/−AT1a+/+, L-FABP−/−AT1a+/−, L-FABP+/−AT1a+/−, L-FABP−/−AT1a−/−, and L-FABP+/−AT1a−/− were administered high-dose systemic ANG II infusion plus a high-salt diet for 28 days. In the L-FABP−/−AT1a+/+, RAS activation (L-FABP−/−AT1a+/+RAS) caused hypertension and tubulointerstitial damage. In the L-FABP+/−AT1a+/+RAS, tubulointerstitial damage was significantly attenuated compared with L-FABP−/−AT1a+/+RAS. In the AT1a partial knockout (AT1a+/−) or complete knockout (AT1a−/−) mice, reduction of AT1a expression led to a significantly lower degree of renal injury compared with L-FABP−/−AT1a+/+RAS or L-FABP+/−AT1a+/+RAS mice. Renal injury in L-FABP+/−AT1a+/−RAS mice was significantly attenuated compared with L-FABP−/−AT1a+/−RAS mice. In both L-FABP−/−AT1a−/−RAS and L-FABP+/−AT1a−/−RAS mice, renal damage was rarely found. The degrees of renal hL-FABP expression and urinary hL-FABP levels increased by RAS activation and gradually decreased along with reduction of AT1a expression levels. In conclusion, in this mouse model, renal hL-FABP expression and a decrease in AT1a expression attenuated tubulointerstitial damage due to RAS activation.

Aliskiren: review of efficacy and safety data with focus on past and recent clinical trials

Aliskiren is the newest antihypertensive drug and the first orally active direct renin inhibitor to become available for clinical use. Clinical data have substantiated that the antihypertensive effectiveness of aliskiren is similar to that of the other major antihypertensive agents. Furthermore, aliskiren has a similar safety profile to placebo. Combination treatment with aliskiren showed significant blood pressure and proteinuria reductions compared with monotherapy. Aliskiren decreases plasma renin activity in contrast to other renin-angiotensin-aldosterone related drugs. The efficacy of aliskiren in treating major cardiovascular events and the prevention of end-organ damage are being investigated in the ASPIRE HIGHER program. Although the first studies of the ASPIRE HIGHER program such as ALOFT, AVOID, AGELESS showed favorable findings, ASPIRE and AVANT-GARDE studies provided contradictory results. Subsequently, the ALTITUDE study was terminated early because of safety issues and lack of beneficial effects. Most recently, the ASTRONAUT trial showed no reduction in cardiovascular death or heart failure rehospitalization with the addition of aliskiren to standard therapy in patients who were hospitalized for heart failure and with reduced left-ventricular ejection fraction. The results of ongoing studies in other patient groups such as the ATMOSPHERE trial are awaited.

Direct Renin inhibitor: aliskiren in chronic kidney disease

The renin-angiotensin-aldosterone system (RAAS) plays pivotal roles in the pathogenesis of chronic kidney disease (CKD) progression and its increased complications such as hypertension (HT) and cardiovascular diseases (CVD). Previous studies suggested that aliskiren a direct renin inhibitor, blocks RAAS and may be effective for the management of CKD and its complications. This review focuses on the effects of aliskiren on CKD.

Aliskiren add-on therapy effectively reduces proteinuria in chronic kidney disease: an open-label prospective trial

INTRODUCTION

The combination therapy of aliskiren and renin-angiotensin-aldosterone system (RAAS) blocker in chronic kidney disease (CKD) is controversial. Whether such dual blockade can effectively apply to patients with CKD irrespective of stage and amount of proteinuria remains uncertain.

METHODS

We added aliskiren at a dosage of 150 mg/day for six months in 103 Chinese CKD patients who had been treated with angiotensin converting enzyme inhibitors (ACEis) or angiotensin receptor blockers (ARBs) and still had significant proteinuria or uncontrolled hypertension. Blood pressure, serum creatinine, estimated glomerular filtration rate (eGFR), potassium, and spot urine protein-to-creatinine ratio (UPCR) were measured at three and six months after aliskiren add-on therapy and compared with baseline.

RESULTS

The combination of aliskiren and ACEi or ARB significantly reduced UPCR by 23% (p=0.001) and mean arterial pressure by 7.9 ± 13.8 mmHg (p<0.001) at six months. Twenty-five percent of subjects had a greater than 50% reduction in UPCR. No significant changes in eGFR and serum potassium level were noted at six months.

CONCLUSIONS

Adding aliskiren on ACEi or ARB in CKD patients, both in diabetes and non-diabetes, has a favorable effect on reducing residual proteinuria and inadequately controlled blood pressure.

Effect of add-on direct renin inhibitor aliskiren in patients with non-diabetes related chronic kidney disease

Background

The renin-angiotensin-aldosterone system (RAAS) plays an important role in the progression of chronic kidney disease (CKD). Although dual RAAS inhibition results in worse renal outcomes than monotherapy in high risk type 2 diabetes patients, the effect of dual RAAS inhibition in patients with non-DM CKD is unclear. The aim of this study was to evaluate the potential renoprotective effect of add-on direct renin inhibitor in non-DM CKD patients.

Methods

We retrospectively enrolled 189 non-DM CKD patients who had been taking angiotensin II receptor blockers (ARBs) for more than six months. Patients were divided into an add-on aliskiren group and an ARB monotherapy group. The primary outcomes were a decline in glomerular filtration rate (GFR) and a reduction in urinary protein-to-creatinine ratio at six months.

Results

The baseline characteristics of the two groups were similar. Aliskiren 150 mg daily reduced the urinary protein-to-creatinine ratio by 26% (95% confidence interval, 15 to 37%; p < 0.001). The decline in GFR was smaller in the add-on aliskiren group (−2.1 vs. -4.0 ml/min, p = 0.038). Add-on aliskiren had a neutral effect on serum potassium in the non-DM CKD patients. In subgroup analysis, the proteinuria-reducing effect of aliskiren was more prominent in patients with a GFR less than 60 ml/min, and in patients with a urinary protein-to-creatinine ratio greater than 1.8. The effect of aliskiren in retarding the decline in GFR was more prominent in patients with hypertensive nephropathy than in those with glomerulonephritis.

Conclusion

Add-on direct renin inhibitor aliskiren (150 mg daily) safely reduced proteinuria and attenuated the decline in GFR in the non-DM CKD patients who were receiving ARBs.

Efficacy analysis of the renoprotective effects of aliskiren in hypertensive patients with chronic kidney disease

We aimed to assess the effect of aliskiren treatment on blood pressure, albuminuria, and kidney function in patients with chronic kidney disease (CKD). We conducted a prospective, open-label study of 67 patients with CKD who were already being treated with other antihypertensives. Inclusion criteria were blood pressure (BP) ≥130/80 mmHg, albuminuria ≥30 mg/g, and estimated glomerular filtration rate (eGFR) >30 ml/min/1.73 m(2). Subjects were treated with 150 mg/day aliskiren, which was increased to 300 mg/day for the 24-week study period. Aliskiren effectively reduced both systolic and diastolic BP, plasma renin activity (PRA), serum aldosterone concentration, albuminuria, urinary N-acetyl-glucosaminidase, and urinary β2-microglobulin levels. Although eGFR was significantly decreased after 4 weeks of aliskiren treatment, it recovered to a pretreatment level within 12 weeks of treatment initiation. There were no significant differences in the percent reduction of albuminuria or changes of eGFR levels when the subjects were divided into three groups on the basis of baseline eGFR (stages 1/2, 3, and 4) and the presence or absence of diabetes mellitus (DM group and non-DM group). Furthermore, in patients not treated with renin-angiotensin-aldosterone-system (RAAS) inhibitors, including angiotensin receptor blockers or angiotensin-converting enzyme inhibitors at baseline, changes in eGFR were significantly increased compared with those already treated with RAAS inhibitors at baseline. Aliskiren administration reduced BP, PRA, serum aldosterone levels, and albuminuria, while maintaining eGFR, regardless of the presence or absence of DM or the degree of eGFR.

Additive renoprotective effects of aliskiren on angiotensin receptor blocker and calcium channel blocker treatments for type 2 diabetic patients with albuminuria

This open-label, randomized, parallel-controlled study investigated the effects of the direct renin inhibitor aliskiren on 64 hypertensive type 2 diabetic patients with chronic kidney disease (CKD) and stable glycemic control who were already being treated with fixed doses of antihypertensive agents over a 24-week period. These agents were 80 mg of the angiotensin II receptor blocker (ARB) telmisartan and 5 mg of the calcium channel blocker (CCB) amlodipine. Patients were randomly assigned to two groups: the aliskiren group, receiving 150 mg per day aliskiren, which was increased to 300 mg per day (n=32), and the CCB group, which received an increased dose (7.5 mg per day) of amlodipine that was increased to 10 mg per day (n=32). Urinary albumin excretion and urinary levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and liver-type fatty acid-binding protein (L-FABP) were investigated in each group. Mean systolic and diastolic blood pressure decreased significantly in both groups, but there was no significant difference between the two groups at the end of the study. Serum creatinine levels and estimated glomerular filtration rate did not differ significantly between the two groups, but percent changes of urinary albumin/creatinine ratios, 8-OHdG and L-FABP levels decreased significantly in the aliskiren group compared with the CCB group. Plasma aldosterone levels were significantly decreased in the aliskiren group, which correlated significantly with those of urinary 8-OHdG and L-FABP. Our results suggest that the addition of aliskiren to the maximal recommended dose of ARB and usual dose of amlodipine is more effective in reducing albuminuria and oxidant stress in hypertensive diabetic patients with CKD than increasing the dose of amlodipine.