Is renoprotection by angiotensin receptor blocker dependent on blood pressure?: the Saitama Medical School, Albuminuria Reduction in Diabetics with Valsartan (STAR) study

Blocking angiotensin 2 receptor attenuates diabetic nephropathy via mitigating ANGPTL2/TL4/NF-κB expression

BACKGROUND

Diabetic nephropathy (DN) is a consequence of diabetes mellitus (DM) and is associated with early changes in renal angiotensin II (ANG II). These changes were evaluated using ANG II blocker valsartan early from week two of diabetes (experiment I, renoprotective) and late from week nine of diabetes (experiment II, renotherapeutic) to the end of both experiments at week twelve.

METHODS AND RESULTS

In both experiments, adult male Wister rats were divided into (i) vehicle group; (ii) valsartan received oral 30 mg/Kg/day; (iii) diabetic received single 50 mg/Kg intraperitoneal streptozotocin injection; (iv) renoprotection, diabetic rats received valsartan treated in experiments I and II. DM effects on urine albumin excretion, blood pressure, and renal ANG II were measured. Urinary nephrin, kidney injury molecule-1 (KIM-1), renal angiopoietin-like protein 2 (ANGPTL2), and toll-like receptor 4 (TLR 4) mRNA expression were tested. DM-initiated fibrotic markers integrin, α-smooth muscle actin expression, and collagen IV and apoptotic protein caspase 3 were tested. DM induced early changes starting from week four in the tested variables. At week twelve, in both experiments, valsartan intervention showed a significant reduction in ANG II, ANGPTL2, TLR 4 and integrin expression and improvement in albuminuria, blood pressure, urinary biomarkers, fibrotic and apoptotic markers.

CONCLUSIONS

Changes leading to DN starts early in the disease course and ANG II reduction decreased the expression of ANGPTL2 and integrin which preserve the glomerular barrier. Blocking ANG II was able to decrease TLR 4 and inflammatory cytokines leading to decreasing DN.

Сhanges in the functional state of the epithelium of the proximal renal tubules in patients with the initial stage of chronic heart failure during simvastatin therapy

To assess the change in the functional state of the proximal renal tubule epithelium in patients with dyslipidemia on the background of obesity, by determining the concentration in the urine of the examined level of cystatin C and the degree of activity of the renal organ-specific enzymes neutral α-glucosidase (NAG) and L-alaninaminopeptidase (laap) during simvastatin therapy at a daily dose of 20 mg for 6 months. The study involved 88 people who were divided into three groups: control, comparison and main. The control group is a group of practically healthy individuals: 30 people, average age 20.67 ± 0.18 years, body mass index (BMI) 21.36 ± 0.4 kg/m2. Comparison group (obese): 27 people, average age 22.38 ± 0.76 years, BMI 31.48 ± 0.56 kg / m2. Patients of the main group were divided into 2 subgroups. The first main subgroup of persons with chronic heart failure stage I (CHF I) without type 2 diabetes mellitus (DM 2)) - 15 observed: average age 56.8 ± 1.8 years, BMI 30.28 ± 1.11 kg / m2. The second main subgroup (CHF I with DM 2) - 16 observed: average age 48.25 ± 2.45 years, BMI 30.37 ± 1.11 kg/m2. The study found that simvastatin therapy does not affect glomerular filtration rate in patients with asymptomatic heart dysfunction. There was an increased level of cystatin C in the urine of the comparison group compared to the control group, the concentration of cystatin C in the main subgroups was statistically significantly higher than the control group. On the background of simvastatin therapy for 6 months, the level of this analyte is statistically significantly increased. The activity of LAAP and NAG during simvastatin therapy during the follow-up period in the CHF I subgroup without DM2 significantly decreased. In the subgroup of CHF I + DM2, a decrease in the concentration of LAAP and an increase in the activity of NAG was revealed, which may indicate that the brush border epithelium dystrophy occurred during simvastatin therapy. Simvastatin therapy for 6 months in patients with the initial stage of heart failure at a daily dosage of 20 mg does not impair glomerular function in the form of reduced glomerular filtration rate (GFR). Cystatin C levels are higher in obese individuals without heart failure and significantly higher in those with asymptomatic heart failure. When treating dyslipidemia with simvastatin at a dose of 20 mg / day, there is a decrease in the activity of NAG and laap in patients with CHF I without DM2. In the result of lipid-lowering therapy with simvastatin in a daily dosage of 20 mg in patients with CHF I+D2M there is increased activity of NAG while reducing the concentration of the LAAP, which may be due to degeneration of the proximal tubular epithelium, amid additional load on a partially renal route of metabolism of simvastatin.

The effects of valsartan on renal glutathione peroxidase expression in alleviation of cyclosporine nephrotoxicity in rats

Introduction: Nephrotoxicity as a side effect caused by the immunosuppressive drug, cyclosporine-A (CsA), can be a major problem in transplant medicine. Oxidative stress may play an important role in the CsA-induced nephrotoxicity. It has been shown that the antihypertensive drug, valsartan (Val), has also renoprotective effects but, its molecular mechanism is largely unknown. In the present study, it was aimed to evaluate the Val effect in the alleviation of CsA nephrotoxicity via probable renal glutathione peroxidase (GPx) upregulation and oxidative stress decrease.

Methods: Thirty-two Sprague-Dawley rats were divided into four groups based on CsA and/or Val administration: group A (Control, 1 mL/kg/day of olive oil as vehicle), group B (CsA, 30 mg/kg/day), group C (CsA+Val, 30+30 mg/kg/day), and group D (Val, 30 mg/kg/day). After the administration period (six weeks), renal GPx expression was evaluated by real-time polymerase chain reaction (PCR). Plasma levels of GPx and 8-Hydroxydeoxyguanosine (8-OHdG) were measured by enzyme-linked immunosorbent assay (ELISA). Malondialdehyde (MDA) and protein carbonyl groups (PCG) were measured by spectrophotometer. Plasma levels of urea and creatinine were measured by an autoanalyzer.

Results: CsA treatment led to the decrease in renal expression and plasma levels of GPx in comparison to other study groups. Rats received CsA were detected to have significantly (p<0.05) higher plasma 8-OHdG, MDA, PCG, urea, and creatinine levels in comparison to other groups. Plasma urea and creatinine levels were negatively correlated with renal GPx expression and positively correlated with the oxidative stress markers.

Conclusion:Administration of Val may result in attenuating the nephrotoxic side effect of CsA via probable renal GPx upregulation, and subsequently oxidative stress decrease.

Clinical and pharmacotherapeutic relevance of the double-chain domain of the angiotensin II type 1 receptor blocker olmesartan

We previously reported that the angiotensin II type 1 (AT(1)) receptor blocker (ARB) olmesartan has two important interactions to evoke inverse agonism (IA). We refer to these interactions as the "double-chain domain (DCD)." Since the clinical pharmacotherapeutic relevance of olmesartan is still unclear, we examined these effects in rats and humans. We analyzed the effects at an advanced stage of renal insufficiency in Dahl salt-sensitive hypertensive rats (Study 1). Rats were fed a high-salt diet from age 9 weeks and arbitrarily assigned to three treatment regimens at age 16 to 21 weeks: olmesartan (2 mg/kg/day) with DCD, a compound related to olmesartan without DCD (6 mg/kg/day, R-239470) or placebo. We also compared the depressor effects of olmesartan to those of other ARBs in patients with essential hypertension (Study 2). Thirty essential hypertensive outpatients who had been receiving ARBs other than olmesartan were recruited for this study. Our protocol was approved by the hospital ethics committee and informed consent was obtained from all patients 12 weeks prior to switching from ARBs other than olmesartan to olmesartan. In Study 1, olmesartan induced a more prominent suppression of the ratio of urinary protein excretion to creatinine at age 21 weeks without lowering blood pressure among the three groups. In Study 2, the depressor effect of olmesartan was significantly stronger than those of other ARBs, which do not contain the DCD. These additive effects by olmesartan may be due to DCD.

Olmesartan for the treatment of arterial hypertension

Angiotensin-receptor blockers (ARBs) are an important class of agents used for the treatment of arterial hypertension. Olmesartan medoxomil, the seventh latest ARB approved by the US FDA, is an oral, once-daily, AT(1)-receptor selective ARB with high receptor affinity. Pharmacologically, it acts as a competitive and insurmountable Ang II antagonist with linear pharmacokinetics and without cytochrome P450 interaction. The drug is licensed for the treatment of arterial hypertension alone or in combination with other antihypertensive agents. Olmesartan has demonstrated its dose-dependent inhibitory effect on Ang I-induced blood pressure responses between 10 and 80 mg in Phase II studies. These results, confirmed in an international clinical trial programme covering over 3000 hypertensive patients in numerous studies, demonstrated rapid blood pressure-lowering effects within 1 week. A daily oral dose of 20 mg olmesartan is considered to be the optimal dose. In clinical trials and postmarketing studies, olmesartan has been shown to be safe and well tolerated with an adverse event profile similar to the placebo. Active comparative studies demonstrated either similar or superior efficacy of olmesartan compared with other ARBs, angiotensin-converting enzymes inhibitors, beta-blockers or calcium-channel blockers. Besides its antihypertensive efficacy, olmesartan was shown in clinical trials to reduce vascular microinflammation, decrease intrarenal vascular resistance, significantly reduce vascular remodeling of small resistance arteries and exert antiatherosclerotic effects by significantly reducing the volume of large atherosclerotic plaques.

Renal protective effect of RAAS blockade across the renal continuum, with a review of the efficacy and safety of valsartan

Abstract Objective: The purpose of this report is to review key data on the angiotensin receptor blocker (ARB) valsartan, along with data from several pivotal studies with other ARBs and angiotensin-converting enzyme (ACE) inhibitors, to highlight the beneficial class effects of renin-angiotensin-aldosterone system (RAAS) blockade throughout the renal continuum.

METHODS

The selection of articles was based on a search of PubMed for clinical trials published between 1997 (the year in which valsartan was approved for sale in the US) and 2009 that involved valsartan and reported effects on renal function, plus a select range of articles on other agents acting on the RAAS, including key guidance documents issued during this time.

SUMMARY

Valsartan has been studied extensively and is widely used for the management of hypertension. Data from clinical studies involving valsartan and other ARBs and ACE inhibitors provide evidence of an additional renal protective effect. This renal protection apparently arises from hemodynamic, endothelial, and anti-inflammatory actions.

LIMITATIONS

Given the extent of the available literature on this topic, this review included only a subset of available publications. This report may reflect inherent heterogeneity between patient populations from these studies and also incorporate the limitations of these individual publications. The inclusion of guidance documents from several organizations may have resulted in apparent minor conflicts in the approaches of the different groups.

Future strategies to prevent renal microvascular disease complications in diabetes

Nephropathy is one of the major chronic microvascular complications of diabetes. The epidemic of Type 2 diabetes and related incidence of end-stage renal disease is progressively increasing worldwide and represents a major public health concern that will seriously challenge any healthcare provider in the world. Despite a number of improvements in patient care, we are still unable to ameliorate or prevent the progression towards end-stage renal disease in the diabetic population. Hypertension and metabolic control appear to interact, resulting in the relentless decline in renal function observed in diabetic patients. Further understanding of the underlying mechanisms, and the development of new treatments against newly identified targets, is crucial for the prevention of this deadly microvascular diabetic complication.