Effects of perindopril on renal histomorphometry in diabetic subjects with microalbuminuria: a 3-year placebo-controlled biopsy study

Angiotensin-converting-enzyme inhibitors and angiotensin receptor blockers for preventing the progression of diabetic kidney disease

BACKGROUND

Guidelines suggest that adults with diabetes and kidney disease receive treatment with angiotensin-converting-enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB). This is an update of a Cochrane review published in 2006.

OBJECTIVES

We compared the efficacy and safety of ACEi and ARB therapy (either as monotherapy or in combination) on cardiovascular and kidney outcomes in adults with diabetes and kidney disease.

SEARCH METHODS

We searched the Cochrane Kidney and Transplants Register of Studies to 17 March 2024 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included studies evaluating ACEi or ARB alone or in combination, compared to each other, placebo or no treatment in people with diabetes and kidney disease.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias and extracted data. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) or standardised mean difference (SMD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

One hundred and nine studies (28,341 randomised participants) were eligible for inclusion. Overall, the risk of bias was high. Compared to placebo or no treatment, ACEi may make little or no difference to all-cause death (24 studies, 7413 participants: RR 0.91, 95% CI 0.73 to 1.15; I2 = 23%; low certainty) and with similar withdrawals from treatment (7 studies, 5306 participants: RR 1.03, 95% CI 0.90 to 1.19; I2 = 0%; low certainty). ACEi may prevent kidney failure (8 studies, 6643 participants: RR 0.61, 95% CI 0.39 to 0.94; I2 = 0%; low certainty). Compared to placebo or no treatment, ARB may make little or no difference to all-cause death (11 studies, 4260 participants: RR 0.99, 95% CI 0.85 to 1.16; I2 = 0%; low certainty). ARB have uncertain effects on withdrawal from treatment (3 studies, 721 participants: RR 0.85, 95% CI 0.58 to 1.26; I2 = 2%; low certainty) and cardiovascular death (6 studies, 878 participants: RR 3.36, 95% CI 0.93 to 12.07; low certainty). ARB may prevent kidney failure (3 studies, 3227 participants: RR 0.82, 95% CI 0.72 to 0.94; I2 = 0%; low certainty), doubling of serum creatinine (SCr) (4 studies, 3280 participants: RR 0.84, 95% CI 0.72 to 0.97; I2 = 32%; low certainty), and the progression from microalbuminuria to macroalbuminuria (5 studies, 815 participants: RR 0.44, 95% CI 0.23 to 0.85; I2 = 74%; low certainty). Compared to ACEi, ARB had uncertain effects on all-cause death (15 studies, 1739 participants: RR 1.13, 95% CI 0.68 to 1.88; I2 = 0%; low certainty), withdrawal from treatment (6 studies, 612 participants: RR 0.91, 95% CI 0.65 to 1.28; I2 = 0%; low certainty), cardiovascular death (13 studies, 1606 participants: RR 1.15, 95% CI 0.45 to 2.98; I2 = 0%; low certainty), kidney failure (3 studies, 837 participants: RR 0.56, 95% CI 0.29 to 1.07; I2 = 0%; low certainty), and doubling of SCr (2 studies, 767 participants: RR 0.88, 95% CI 0.52 to 1.48; I2 = 0%; low certainty). Compared to ACEi plus ARB, ACEi alone has uncertain effects on all-cause death (6 studies, 1166 participants: RR 1.08, 95% CI 0.49 to 2.40; I2 = 20%; low certainty), withdrawal from treatment (2 studies, 172 participants: RR 0.78, 95% CI 0.33 to 1.86; I2 = 0%; low certainty), cardiovascular death (4 studies, 994 participants: RR 3.02, 95% CI 0.61 to 14.85; low certainty), kidney failure (3 studies, 880 participants: RR 1.36, 95% CI 0.79 to 2.32; I2 = 0%; low certainty), and doubling of SCr (2 studies, 813 participants: RR 1.14, 95% CI 0.70 to 1.85; I2 = 0%; low certainty). Compared to ACEi plus ARB, ARB alone has uncertain effects on all-cause death (7 studies, 2607 participants: RR 1.02, 95% CI 0.76 to 1.37; I2 = 0%; low certainty), withdrawn from treatment (3 studies, 1615 participants: RR 0.81, 95% CI 0.53 to 1.24; I2 = 0%; low certainty), cardiovascular death (4 studies, 992 participants: RR 3.03, 95% CI 0.62 to 14.93; low certainty), kidney failure (4 studies, 2321 participants: RR 1.15, 95% CI 0.67 to 1.95; I2 = 29%; low certainty), and doubling of SCr (3 studies, 2252 participants: RR 1.18, 95% CI 0.85 to 1.64; I2 = 0%; low certainty). Comparative effects of different ACEi or ARB and low-dose versus high-dose ARB were rarely evaluated. No study compared different doses of ACEi. Adverse events of ACEi and ARB were rarely reported.

AUTHORS' CONCLUSIONS

ACEi or ARB may make little or no difference to all-cause and cardiovascular death compared to placebo or no treatment in people with diabetes and kidney disease but may prevent kidney failure. ARB may prevent the doubling of SCr and the progression from microalbuminuria to macroalbuminuria compared with a placebo or no treatment. Despite the international guidelines suggesting not combining ACEi and ARB treatment, the effects of ACEi or ARB monotherapy compared to dual therapy have not been adequately assessed. The limited data availability and the low quality of the included studies prevented the assessment of the benefits and harms of ACEi or ARB in people with diabetes and kidney disease. Low and very low certainty evidence indicates that it is possible that further studies might provide different results.

Effects of renin-angiotensin system blockers on renal and cardiovascular outcomes in patients with diabetic nephropathy: a meta-analysis of randomized controlled trials

PURPOSE

This study aimed to evaluate the effect f angiotensin-converting enzyme inhibitors (ACEI) and angiotensin receptor blockers (ARB) on renal or cardiovascular outcomes in patients with diabetic nephropathy (DN).

METHODS

PubMed, Embase, and Cochrane Library were searched for randomized controlled trials (RCTs) evaluating the treatment effects of ACEI and ARB on renal or cardiovascular outcomes in patients with DN until August 2017. The outcomes included end-stage renal disease (ESRD), doubling of serum creatinine levels, all-cause mortality, major cardiovascular events (MACEs), myocardial infarction (MI), stroke, and cardiac death. Relative risks (RR) with 95% confidence intervals (CIs) were used for calculating the summary results using a random-effects model.

RESULTS

Twenty-four RCTs including 57,818 patients with DN and 891 events of ESRD, 1050 doubling of serum creatinine concentration, 4352 all-cause mortality, 6342 MACEs, 1073 MI, 2900 stroke, and 1674 cardiac deaths were reported. Overall, the summary results suggested that in patients with DN, receiving ACEI did not have a significant effect on ESRD, doubling of serum creatinine levels, all-cause mortality, MI, stroke, and cardiac death, while ACEI significantly reduced the risk of total MACEs. Furthermore, ARB therapy was associated with a low risk of ESRD and doubling of serum creatinine levels, while it did not differ significantly on all-cause mortality, MACEs, MI, stroke, and cardiac death in patients with DN.

CONCLUSIONS

Patients with DN receiving ACEI had significantly reduced the risk of total MACEs, and ARB could reduce the incidence of ESRD and the doubling of serum creatinine levels.

Vascular legacy beyond blood pressure control: benefits of perindopril/indapamide combination in hypertensive patients with diabetes

OBJECTIVES

Much of the chronic care of patients with type 2 diabetes mellitus and hypertension involves the prevention of diabetic complications. Renin-angiotensin system inhibitors are recommended as first-line therapies because of their nephroprotective properties. Their combination with metabolically neutral diuretics is recommended to reduce blood pressure, morbidity and mortality. Our objective was to review the mechanisms by which the combination of the angiotensin-converting enzyme inhibitor, perindopril, and metabolically neutral thiazide-like diuretic, indapamide, targets the pathways involved in microvascular and macrovascular diabetic complications.

METHODS

For this narrative review, extensive literature searches were performed using PubMed/Medline. Articles published in English describing clinical trials and mechanism of action studies that were relevant to the treatment of patients with perindopril and/or indapamide were included.

RESULTS

Perindopril/indapamide treatment has been shown to reduce blood pressure and to have significant beneficial effects on arterial distensibility, kidney structure and function, and endothelial function. Recent data also suggests that perindopril may reduce the deleterious accumulation of advanced glycation end products in diabetic tissue. In the Action in Diabetes and Vascular Disease: Preterax and Diamicron MR Controlled Evaluation diabetes trial, perindopril/indapamide treatment significantly reduced the relative risk of microvascular and macrovascular events by 9%, cardiovascular mortality by 18%, and all-cause mortality by 14%. Interestingly, 6 years after the end of the double-blind period, follow-up data showed that the beneficial effects on mortality continued to be significant even though differences in blood pressure and glycated hemoglobin levels had not been significant for several years. Together this data suggests that treatment with perindopril/indapamide has microvascular and macrovascular effects that extend beyond blood pressure lowering and that this treatment might confer a long-lasting beneficial vascular legacy.

CONCLUSION

Moving forward, understanding the pathophysiological bases of the effects that extend beyond those of blood pressure control will help us differentiate between anti-hypertensive choices.

Renin-Angiotensin System Inhibitors and Kidney and Cardiovascular Outcomes in Patients With CKD: A Bayesian Network Meta-analysis of Randomized Clinical Trials

BACKGROUND

There is much uncertainty regarding the relative effects of angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) in populations with chronic kidney disease (CKD).

STUDY DESIGN

Systematic review and Bayesian network meta-analysis.

SETTING & POPULATION

Patients with CKD treated with renin-angiotensin system (RAS) inhibitors.

SELECTION CRITERIA FOR STUDIES

Randomized trials in patients with CKD treated with RAS inhibitors.

PREDICTOR

ACE inhibitors and ARBs compared to each other and to placebo and active controls.

OUTCOME

Primary outcome was kidney failure; secondary outcomes were major cardiovascular events, all-cause death.

RESULTS

119 randomized controlled trials (n = 64,768) were included. ACE inhibitors and ARBs reduced the odds of kidney failure by 39% and 30% (ORs of 0.61 [95% credible interval, 0.47-0.79] and 0.70 [95% credible interval, 0.52-0.89]), respectively, compared to placebo, and by 35% and 25% (ORs of 0.65 [95% credible interval, 0.51-0.80] and 0.75 [95% credible interval, 0.54-0.97]), respectively, compared with other active controls, whereas other active controls did not show evidence of a significant effect on kidney failure. Both ACE inhibitors and ARBs produced odds reductions for major cardiovascular events (ORs of 0.82 [95% credible interval, 0.71-0.92] and 0.76 [95% credible interval, 0.62-0.89], respectively) versus placebo. Comparisons did not show significant effects on risk for cardiovascular death. ACE inhibitors but not ARBs significantly reduced the odds of all-cause death versus active controls (OR, 0.72; 95% credible interval, 0.53-0.92). Compared with ARBs, ACE inhibitors were consistently associated with higher probabilities of reducing kidney failure, cardiovascular death, or all-cause death.

LIMITATIONS

Trials with RAS inhibitor therapy were included; trials with direct comparisons of other active controls with placebo were not included.

CONCLUSIONS

Use of ACE inhibitors or ARBs in people with CKD reduces the risk for kidney failure and cardiovascular events. ACE inhibitors also reduced the risk for all-cause mortality and were possibly superior to ARBs for kidney failure, cardiovascular death, and all-cause mortality in patients with CKD, suggesting that they could be the first choice for treatment in this population.

Vaccination against type 1 angiotensin receptor prevents streptozotocin-induced diabetic nephropathy

Abstract

Recently, our group has developed a therapeutic hypertensive vaccine against angiotensin (Ang) II type 1 receptor (AT1R) named ATRQβ-001. To explore its potential effectiveness on streptozotocin-induced diabetic nephropathy, male Sprague Dawley rats were randomly divided into two groups: a control and a diabetic model. After 1 week, the diabetic rats were divided into four subgroups (each with 15 rats) for 14-week treatments with saline, olmesartan, ATRQβ-001, and Qβ virus-like particle (VLP), respectively. In addition to lower blood pressure, ATRQβ-001 vaccination ameliorated biochemical parameter changes of renal dysfunction, mesangial expansion, and fibrosis through inhibiting oxidative stress, macrophage infiltration, and proinflammatory factor expression. Furthermore, ATRQβ-001 vaccination suppressed renal Ang II-AT1R activation and abrogated the downregulation of angiotensin-converting enzyme 2-Ang (1–7), similar to olmesartan treatment, while no obvious feedback activation of circulating or local renin-angiotensin system (RAS) was only observed in vaccine group. In rat mesangial cells, the anti-ATR-001 antibody inhibited high glucose-induced transforming growth factor-β1 (TGF)-β1/Smad3 signal pathway. Additionally, no significant immune-mediated damage was detected in vaccinated animals. In conclusion, the ATRQβ-001 vaccine ameliorated streptozotocin-induced diabetic renal injury via modulating two RAS axes and inhibiting TGF-β1/Smad3 signal pathway, providing a novel, safe, and promising method to treat diabetic nephropathy.

Key messages

Overactivation of RAS plays a crucial role in the development of the DN.

Our aim was to verify the effectiveness of ATRQβ-001 vaccine in STZ-induced DN.

The ATRQβ-001 modulated two RAS axes and inhibited TGF-β1/Smad3 signal pathway.

The vaccine therapy may provide a novel, safe, and promising method to treat DN.

Electronic supplementary material

The online version of this article (doi:10.1007/s00109-015-1343-6) contains supplementary material, which is available to authorized users.

Adherence and renal biopsy feasibility in the Renin Angiotensin-System Study (RASS) primary prevention diabetes trial

AIMS

Enhancing adherence in research trials is fundamental to the proper testing of treatment hypotheses.

METHODS

Regimen and follow-up adherence as well as factors associated with adherence in the Renin Angiotensin-System Study (RASS) diabetic nephropathy primary prevention trial were evaluated. Adherence to medication (i.e., pill count), follow-up visits, and follow-up renal biopsies was evaluated.

RESULTS

89.8% of subjects completed the second renal biopsy. 96% of follow-up visits were attended within prescribed time windows. Mean medication adherence was 85.6%. Subgroup analyses revealed greater declines in the least adherent participants over time. Factors associated with greater adherence levels included older age, type 1 diabetes (TIDM) duration, lower HbA1c and blood pressure, GFR, ethnicity, and participants', principal investigators' (PI), and trial coordinators' (TC) baseline predictions of adherence.

CONCLUSIONS

T1DM patients without nephropathy were willing to take experimental medications and undergo repeat renal biopsies. Although overall adherence was excellent, patterns of adherence varied among participants, suggesting the need to better track adherence and to develop customized and targeted approaches for promoting adherence to clinical research regimens. Staff subjective predictions of adherence were imprecise, supporting need for further development of adherence predictors.

Angiotensin-converting enzyme inhibitors, angiotensin receptor blockers and combined therapy in patients with micro- and macroalbuminuria and other cardiovascular risk factors: a systematic review of randomized controlled trials

BACKGROUND

A recent clinical trial showed harmful renal effects with the combined use of angiotensin-converting enzyme inhibitors (ACEI) and angiotensin-II receptor blockers (ARB) in people with diabetes or vascular disease. We examined the benefits and risks of these agents in people with albuminuria and one or more cardiovascular risk factors.

METHODS

MEDLINE, EMBASE and Renal Health Library were searched for trials comparing ACEI, ARB or their combination with placebo or with one another in people with albuminuria and one or more cardiovascular risk factor.

RESULTS

Eighty-five trials (21,708 patients) were included. There was no significant reduction in the risk of all-cause mortality or fatal cardiac-cerebrovascular outcomes with ACEI versus placebo, ARB versus placebo, ACEI versus ARB or with combined therapy with ACEI + ARB versus monotherapy. There was a significant reduction in the risk of nonfatal cardiovascular events with ACEI versus placebo but not with ARB versus placebo, ACEI versus ARB or with combined therapy with ACEI + ARB versus monotherapy. Development of end-stage kidney disease and progression of microalbuminuria to macroalbuminuria were reduced significantly with ACEI versus placebo and ARB versus placebo but not with combined therapy with ACEI + ARB versus monotherapy.

CONCLUSIONS

ACEI and ARB exert independent renal and nonfatal cardiovascular benefits while their effects on mortality and fatal cardiovascular disease are uncertain. There is a lack of evidence to support the use of combination therapy. A comparative clinical trial with ACE, ARB and its combination in people with albuminuria and a cardiovascular risk factor is warranted.

The role of renin angiotensin system inhibition in kidney repair

Chronic kidney diseases share common pathogenic mechanisms that, independently from the initial injury, lead to glomerular hyperfiltration, proteinuria, and progressive renal scarring and function loss. Inhibition of the renin angiotensin system (RAS) has been consistently found to reduce or halt the progressive deterioration of renal function through reduction of blood pressure and proteinuria, the two main determinants of renal function decline. In few instances, RAS inhibition may even promote amelioration of the glomerular filtration rate. Animal data suggest that chronic therapy with angiotensin-converting enzyme inhibitors or angiotensin II receptor type I blockers promotes regression of glomerulosclerosis, even in later phases of the disease. In humans, studies investigating the effect of angiotensin II inhibition on renal structural changes have shown inconsistent results, possibly due to small numbers and/or short duration of follow-up. Whether regression of glomerulosclerosis relies on a direct regenerative effect of RAS inhibition or on spontaneous kidney self-repair after the injury has been removed is still unknown. Improved understanding of mechanisms that promote renal regeneration may help in designing specific therapies to prevent the development of end-stage renal disease. This is a desirable goal, considering the economic burden of chronic kidney diseases and their effect on morbidity and mortality.

Altered Renal Function in Normoalbuminuric Type 2 Diabetes

Altered renal function namely enhanced FE Mg and impaired hemodynamics is observed in normoalbuminuric type 2 diabetes. Since FE Mg correlates directly with tubulointerstitial fibrosis, enhanced FE Mg reflects tubulointerstitial disease even in normoalbuminuric type 2 diabetes. This implies that microalbuminuria is not sensitive to early detect diabetic nephropathy.

Microalbuminuria--a biomarker of renal microvascular disease

Microalbuminuria (amount greater than 30-300 mg/day) reflects an abnormal glomerular capillary permeability to protein. It is usually dependent upon three mechanisms. First, loss of negatively charged surface of the glomerular capillary wall secondary to circulating toxic substances injury-namely, oxidative stress and proinflammatory cytokines-allows the albumin with negatively charged surface to freely escape into the urine. Second, intraglomerular hypertension and hemodynamic maladjustment secondary to glomerular endothelial dysfunction increases filtration pressure and enhances sized selective proteinuria leakage. Third, podocyte injury leads to a vicious cycle of hemodynamic maladjustment and endothelial and podocyte injuries. All three of these mechanisms induce glomerular endothelial injury and microalbuminuria, which reflects renal microvascular disease.

Effects of renin-angiotensin system blockers on renal outcomes and all-cause mortality in patients with diabetic nephropathy: an updated meta-analysis

BACKGROUND

In contrast to previous studies, recent data questioned the ability of renin-angiotensin-aldosterone system (RAAS) blockers to delay progression of diabetic nephropathy. This study evaluated the effect of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin-receptor blockers (ARBs) in patients with diabetic nephropathy.

METHODS

A systematic literature search of MEDLINE/PubMed and EMBASE databases was performed to identify randomized trials published up to June 2007 comparing the effects of ACEIs or ARBs with placebo and/or a regimen not including a RAAS blocker on the incidence of end-stage renal disease (ESRD), doubling of serum creatinine (DSC), or death from any cause in patients with diabetic nephropathy. Treatment effects were summarized as relative risks (RRs) using the Mantel-Haenszel fixed-effects model.

RESULTS

Of the 1,028 originally identified studies, 24 fulfilled the inclusion criteria (20 using ACEIs and 4 using ARBs). Use of ACEIs was associated with a trend toward reduction of ESRD incidence (RR 0.70; 95% confidence interval (CI) 0.46-1.05) and use of ARBs with significant reduction of ESRD risk (RR 0.78; 95% CI 0.67-0.91). Both drug classes were associated with reduction in the risk of DSC (RR 0.71; 95% CI 0.56-0.91 for ACEIs and RR 0.79; 95% CI 0.68-0.91 for ARBs) but none affected all-cause mortality (RR 0.96; 95% CI 0.85-1.09 for ACEIs and RR 0.99; 95% CI 0.85-1.16 for ARBs).

CONCLUSION

Treatment of patients with diabetic nephropathy with a RAAS blocker reduces the risks of ESRD and DSC, but does not affect all-cause mortality. These findings are added to the evidence of a renoprotective role of RAAS blockers in such patients.

A cost-effectiveness analysis of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in diabetic nephropathy

The aim of this study was to estimate the cost-effectiveness of renin-angiotensin-aldosterone system blockers in patients with diabetic nephropathy. A cost-effectiveness analysis was performed based on a meta-analysis of studies investigating the effect of angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) as part of a treatment regimen on the incidence of end-stage renal disease (ESRD) in patients with diabetic nephropathy. The primary outcome was the cost to prevent 1 patient from developing ESRD. Cost analysis was performed from a third-party payer perspective in 2006 US dollars. As part of a treatment regimen, ARBs significantly reduced the incidence of ESRD and doubling of serum creatinine concentration (P<.05) but not total mortality. The cost to prevent 1 patient from developing ESRD was $31,729 (95% confidence interval, $19,443-$85,442; P<.01), $189,190 (P=.13) and $51,585 (P=.068) for patients receiving ARBs, ACE inhibitors, or either of them, respectively. This study demonstrates that blocking the RAAS, which delays the progression to ESRD, appears to be cost-effective. The current analysis favors ARBs in terms of cost-effectiveness.

Lowering of proteinuria in response to antihypertensive therapy predicts improved renal function in late but not in early diabetic nephropathy: a pooled analysis

In late diabetic nephropathy (DN) the initial lowering of albumin excretion rate (AER) with antihypertensive therapy is proportional to the degree of subsequent preservation of glomerular filtration rate (GFR). Whether a similar relationship exists between AER and GFR in early diabetes is not known. The present analysis has compared AER and GFR responses to antihypertensive therapy in 33 published studies (77 treatment groups) of early and late DN in type 1 (T1) and type 2 (T2) diabetes, analyzed on an intention-to-treat basis. Prospective trials were included if the initial change in AER during the first year of therapy and the change in GFR during at least 2 years of follow-up could be estimated from group mean data. The initial % decreases in AER were 5.9 +/- 4.3 (T1), 10.5 +/- 5.4 (T2, normotensive) and 18.4 +/- 6.2 (T2, hypertensive) in early DN and 7.6 +/- 11.1 (T1) and 20.8 +/- 5.5 (T2) in late DN. The corresponding annual % rates of decline of GFR were 2.0 +/- 0.5 (T1), 1.6 +/- 0.5 (T2, normotensive) and 2.1 +/- 0.3 (T2, hypertensive) in early DN and 9.8 +/- 1.5 (T1) and 9.2 +/- 1.1 (T2) in late DN. AER and GFR responses in each treatment group were closely correlated in late nephropathy (T1, r = -0.67, p = 0.03; T2, r = 0.57, p = 0.02) but not in early nephropathy. In contrast to late DN, the initial decrease in AER with antihypertensive therapy was not shown to predict the subsequent rate of decline of GFR in early DN. It follows that assessment of renoprotection during antihypertensive therapy in early nephropathy should be based not only on albuminuria but also on the GFR response.

Aliskiren, a novel renin inhibitor, is renoprotective in a model of advanced diabetic nephropathy in rats

AIMS/HYPOTHESIS

Blockade of the renin-angiotensin system (RAS) with either ACE inhibitors or angiotensin receptor blocker is a key therapeutic strategy in slowing progression of diabetic nephropathy. Interruption of the RAS may also be achieved by blocking the activity of renin, the rate-limiting step in angiotensin II biosynthesis. However, it is not known whether drugs in this class also reduce the structural and functional manifestations of diabetic nephropathy.

METHODS

Using diabetic transgenic (mRen-2)27 rats, a rodent model of advanced diabetic nephropathy, we compared the efficacy of the renin inhibitor, aliskiren (10 mg kg(-1) day(-1) by osmotic mini-pump), with the ACE inhibitor, perindopril (0.2 mg kg(-1) day(-1) in drinking water), over a 16 week period.

RESULTS

Both perindopril and aliskiren reduced blood pressure, albuminuria and structural injury in experimental diabetic nephropathy, although not to the same extent. Aliskiren, at the dose used, did not reduce systemic blood pressure as much as perindopril, but both compounds were equally effective in reducing albuminuria and glomerulosclerosis in diabetic animals. The magnitude of interstitial fibrosis was attenuated to a greater degree by aliskiren than by perindopril.

CONCLUSIONS/INTERPRETATION

These findings suggest that therapies aimed at different targets within the RAS may not have identical effects in attenuating structural injury in experimental diabetic nephropathy.

Novel insights in the treatment of diabetic nephropathy

Diabetes is currently one of the leading causes of end-stage renal failure requiring renal replacement therapy in the Western World. About 15% to 20% of type 1 diabetic patients and 30% to 40% of type 2 diabetic patients will eventually develop end-stage renal failure. To prevent the development or progression of diabetic kidney disease, good glycaemic control remains the cornerstone in the management of diabetic patients. Beyond glycaemic control, other metabolic factors have been shown to be involved in the development of diabetic kidney disease, i.e. advanced glycation endproducts (AGEs) and the aldose reductase pathway. Furthermore, an adequate control of high blood pressure and treatment of microalbuminuria are major therapeutic targes. To achieve adequate blood pressure control, a combination therapy with different classes of antihypertensive agents is often necessary, especially including angiotensin-converting enzyme inhibitors and angiotensin receptor blockers. Other vasoactive factors involved in diabetic nephropathy such as endothelin and nitric oxide will be covered briefly. Besides hyperglycaemia and high blood pressure, other risk factors have been identified in the development or progression of diabetic kidney disease: smoking, hyperlipidaemia, obesity and high protein intake. Their impact on renal function will be highlighted. Finally, recent research has also identified intracellular pathways such as the diacylglycerol-protein kinase C pathway and several growth factors, such as growth hormone, insulin-like growth factor, transforming growth factor-beta, vascular endothelial growth factor, and platelet derived growth factor as players in diabetic kidney disease.

Effects of perindopril in hypertensive patients with or without type 2 diabetes mellitus, and with altered insulin sensitivity

Impaired insulin sensitivity and hypertension are risk factors for atherosclerosis, which in turn leads to a variety of cardiovascular diseases. In both conditions, the risks of morbidity and mortality appear to be further increased. Impaired insulin sensitivity is also a precursor for diabetes. The renin-angiotensin-aldosterone system (RAAS) is implicated in the development of both hypertension and insulin resistance. Antihypertensive agents that act by blocking the RAAS, such as angiotensin-converting enzyme (ACE) inhibitors, may improve insulin sensitivity and therefore prevent the deleterious consequences of insulin resistance, including type 2 diabetes. ACE inhibitors appear to improve insulin sensitivity in patients with hypertension and insulin resistance, including diabetes. This review assesses the literature surrounding the use of the ACE inhibitor perindopril in patients with hypertension and varying degrees of insulin resistance, including the effects of perindopril in preventing the development of diabetes and subsequent cardiovascular morbidity and mortality.

Angiotensin converting enzyme inhibitors and angiotensin II receptor antagonists for preventing the progression of diabetic kidney disease

BACKGROUND

Angiotensin converting enzyme inhibitors (ACEi) and angiotensin II receptor antagonists (AIIRA) are considered to be equally effective for patients with diabetic kidney disease (DKD), but renal and not mortality outcomes have usually been considered.

OBJECTIVES

To evaluate the benefits and harms ACEi and AIIRA in patients with DKD.

SEARCH STRATEGY

We searched MEDLINE (1966 to December 2005), EMBASE (1980 to December 2005), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library issue 4 2005) and contacted known investigators.

SELECTION CRITERIA

Studies comparing ACEi or AIIRA with placebo or each other in patients with DKD were included.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. Statistical analyses were performed using the random effects model and results expressed as relative risk (RR) with 95% confidence intervals (CI). Heterogeneity among studies was explored using the Cochran Q statistic and the I(2) test, subgroup analyses and random effects metaregression.

MAIN RESULTS

Fifty studies (13,215 patients) were identified. Thirty eight compared ACEi with placebo, five compared AIIRA with placebo and seven compared ACEi and AIIRA directly. There was no significant difference in the risk of all-cause mortality for ACEi versus placebo (RR 0.91, 95% CI 0.71 to 1.17) and AIIRA versus placebo (RR 0.99, 95% CI 0.85 to 1.17). A subgroup analysis of studies using full-dose ACEi versus studies using half or less than half the maximum tolerable dose of ACEi showed a significant reduction in the risk of all-cause mortality with the use of full-dose ACEi (RR 0.78, 95% CI 0.61 to 0.98). Baseline mortality rates were similar in the ACEi and AIIRA studies. The effects of ACEi and AIIRA on renal outcomes (ESKD, doubling of creatinine, prevention of progression of micro- to macroalbuminuria, remission of micro- to normoalbuminuria) were similarly beneficial. Reliable estimates of effect of ACEi versus AIIRA could not be obtained from the three studies in which they were compared directly because of their small sample size.

AUTHORS' CONCLUSIONS

Although the survival benefits of ACEi are known for patients with DKD, the relative effects on survival of ACEi with AIIRA are unknown due to the lack of adequate direct comparison studies. In placebo controlled studies, only ACEi (at the maximum tolerable dose, but not lower so-called renal doses) were found to significantly reduce the risk of all-cause mortality. Renal and toxicity profiles of these two classes of agents were not significantly different.

Prevention of loss of renal function over time in patients with diabetic nephropathy

Management of hypertension is the mainstay of prevention and treatment of diabetic renal disease; evidence suggests that tight blood pressure control slows renal disease progression in established diabetic nephropathy. Inhibition of the renin-angiotensin-aldosterone system (RAAS) has renoprotective effects over and above those achieved by lowering systemic blood pressure. To date, however, no long-term study using hard end points has directly compared current mechanisms for RAAS inhibition, angiotensin II receptor blockade (ARB) and angiotensin-converting enzyme (ACE) inhibition. This issue was addressed in the recently published Diabetics Exposed to Telmisartan and Enalapril (DETAIL) study, a head-to-head comparison of telmisartan and enalapril in 250 patients with hypertension and type 2 diabetes mellitus and early-stage nephropathy. After 5 years' treatment, change in glomerular filtration rate (GFR), the primary efficacy end point, was equivalent in the 2 treatment groups, as were all secondary end points. The expected steep decline in GFR in the first year was followed by a lesser decrease in the second year and then almost complete stabilization of renal function at > or =3 years. Over 5 years, no patient went into end-stage renal disease or required dialysis. There were also no increases in albumin excretion rate, nor was there an increase in creatinine beyond 200 mumol/L. Incidence of cardiovascular morbidity and mortality was extremely low in both treatment groups, a remarkable outcome given that almost 50% of patients had evidence of cardiovascular disease at randomization. Inhibition of the RAAS should play a major part in management of patients with type 2 diabetes with nephropathy, for which both telmisartan and enalapril provide long-term renoprotection.

Beneficial effect of angiotensin-blocking agents on graft fibrosis in hepatitis C recurrence after liver transplantation

BACKGROUND

Hepatitis C recurrence after liver transplantation is often associated with accelerated graft fibrosis and progression to cirrhosis. Because drugs blocking the action of angiotensin-II can reduce fibrosis in different human and experimental models, we assessed the possible beneficial effect of these drugs on graft fibrosis in hepatitis C recurrence after liver transplantation.

METHODS

We retrospectively reviewed the charts of 128 liver-transplant recipients with hepatitis C recurrence. Twenty-seven patients (group I) received angiotensin converting enzyme inhibitors or angiotensin-II receptor antagonists as antihypertensive treatment, and 101 patients (group II) did not receive these drugs.

RESULTS

No significant differences were found between groups I and II in demographic, clinical, and laboratory data. In contrast, cirrhosis in the graft was less frequently observed in group I than in group II during postransplant follow-up: 15% versus 35% (P=0.035), respectively, with a probability of cirrhosis of 9% versus 32% at 5 years after transplantation and 35% versus 70% at 10 years (P=0.0049). Furthermore, the fibrosis stage (scored from 0-4) in the liver biopsy obtained at the end of follow-up was significantly lower in group I than in group II (median [and range]: 1 [0-4] vs. 2 [0-4]; P=0.038), and the fibrosis progression index (increase of fibrosis stage per year) was also lower in group I than in group II (0.21 [0-0.45] vs. 0.52 [0-2.58]; P=0.006).

CONCLUSION

The administration of angiotensin-blocking agents may be beneficial to reduce the development of graft fibrosis in hepatitis C recurrence after liver transplantation.

From hyperglycemia to diabetic kidney disease: the role of metabolic, hemodynamic, intracellular factors and growth factors/cytokines

At present, diabetic kidney disease affects about 15-25% of type 1 and 30-40% of type 2 diabetic patients. Several decades of extensive research has elucidated various pathways to be implicated in the development of diabetic kidney disease. This review focuses on the metabolic factors beyond blood glucose that are involved in the pathogenesis of diabetic kidney disease, i.e., advanced glycation end-products and the aldose reductase system. Furthermore, the contribution of hemodynamic factors, the renin-angiotensin system, the endothelin system, and the nitric oxide system, as well as the prominent role of the intracellular signaling molecule protein kinase C are discussed. Finally, the respective roles of TGF-beta, GH and IGFs, vascular endothelial growth factor, and platelet-derived growth factor are covered. The complex interplay between these different pathways will be highlighted. A brief introduction to each system and description of its expression in the normal kidney is followed by in vitro, experimental, and clinical evidence addressing the role of the system in diabetic kidney disease. Finally, well-known and potential therapeutic strategies targeting each system are discussed, ending with an overall conclusion.

Ambulatory blood pressure in type 2 diabetic patients with albuminuria: relation to the renal function and structural lesions

BACKGROUND/AIMS

To investigate possible relationships between ambulatory blood pressure (BP) and renal structure and function in type 2 diabetic patients.

METHODS

Renal biopsies were performed on 39 patients with urine albumin concentrations above 100 mg/l. BP was investigated with a 24-h, automated, portable BP device.

RESULTS

None of the patients in the study had signs of other renal disease than nephrosclerosis or diabetic nephropathy. Ten patients had slight, 13 intermediate, and 6 severe diabetic nephropathy on the renal biopsy. Among the remaining patients, 4 had normal microscopy findings and 6 had nephrosclerosis. The degree of albuminuria correlated to the systolic BP during the day (r = .43; P < .01) and night (r = .49; P < .01). The glomerular filtration rate (GFR) was associated with the systolic BP daytime (r = -.32; P < .05) and nighttime (r = -.47; P < .01). Neither degree of albuminuria nor GFR was associated with the diastolic BP levels. The degree of the glomerular pathology correlated to the systolic BP during daytime (P < .05), whereas the degree of interstitial fibrosis did not correlate to the BP levels.

CONCLUSIONS

We have demonstrated that degree of albuminuria and GFR was significantly associated with daytime and nocturnal BP and glomerular structure with daytime BP. Furthermore, no renal disease other than diabetic nephropathy was found.

The renin-angiotensin system and the long-term complications of diabetes: pathophysiological and therapeutic considerations

The relationship between the renin-angiotensin system (RAS) and the progression of diabetic renal disease has been a major focus of investigation over the past 20 years. More recently, experimental and clinical studies have also suggested that the RAS may have a pathogenetic role at other sites of micro- and macrovascular injury in diabetes. Complementing major advances into the understanding of the local, as distinct from the systemic RAS, a number of large clinical trials have examined whether blockade of the RAS might provide protection from the long-term complications of diabetes, beyond that due to blood pressure reduction alone. While some controversy remains, these studies have, in general, suggested that angiotensin converting enzyme (ACE) inhibition and more recently, angiotensin receptor blockade reduce the development and progression of diabetic nephropathy, cardiovascular disease and possibly retinopathy. This review will focus on recent developments in our understanding of the tissue-based RAS and its role in end-organ injury in diabetes, the results of recent clinical trials and newer strategies for the pharmacological manipulation of the RAS.

Effects of low-dose and early versus late perindopril treatment on the progression of severe diabetic nephropathy in (mREN-2)27 rats

It was previously reported that transgenic (mRen-2)27 rats with streptozotocin-induced diabetes mellitus progressively develop advanced nephropathy in 12 wk. These lesions are largely prevented when the angiotensin-converting enzyme inhibitor perindopril is administered from the time of induction of diabetes mellitus. This study aimed to determine the lowest dose of early perindopril treatment required for substantial improvement of renal function and structure and to investigate whether late intervention prevents or reverses the progression of established renal lesions. At 6 wk of age, female heterozygous Ren-2 rats were randomized to receive either streptozotocin (diabetic) or citrate buffer (control). Rats were gavaged, beginning early after the induction of diabetes mellitus or the administration of control vehicle, with 0, 0.02, 0.2, or 2 mg/kg per d perindopril for 12 wk. A separate group of diabetic Ren-2 rats received late treatment with 2 mg/kg per d perindopril throughout week 8 to week 12, when rats were hypertensive and albuminuric and exhibited increased kidney weight and glomerulosclerotic index (GSI). Among diabetic rats, early 0.02 mg/kg per d perindopril treatment reduced systolic BP, GSI, and renal collagen staining but had no effect on albuminuria or kidney hypertrophy. Early 0.2 or 2 mg/kg per d perindopril treatment further reduced systolic BP, GSI, and renal collagen staining and decreased albuminuria and kidney hypertrophy. Late intervention was as antihypertensive and antialbuminuric as early 0.2 or 2 mg/kg per d perindopril treatment but did not prevent a moderate increase in GSI. In conclusion, early treatment with 0.2 mg/kg per d perindopril was the lowest dosage to largely prevent severe diabetic nephropathy in transgenic Ren-2 rats. Late-onset perindopril treatment of diabetic rats with established nephropathy was as efficacious as early treatment with respect to various renal parameters, such as albuminuria, but was associated with moderate progression of glomerulosclerosis.

Does ACE inhibition slow progression of glomerulopathy in patients with Type 2 diabetes mellitus?

AIMS

To examine the effect of ACE inhibition on glomerular structure in Type 2 diabetic patients with nephropathy.

METHODS

Twenty-two patients were randomized to receive either perindopril (PE) or placebo (PO) and biopsied at baseline and after 2 years. Nineteen patients completed the study and data on interstitial changes, examined by light microscopy, have already been published. Only 11 patients (five PE, six PO) had sufficient tissue at baseline and follow-up to provide material for detailed electron microscopic examination.

RESULTS

At baseline, mean +/- sd age (PE vs. PO) was 48 +/- 12 vs. 45 +/- 7 years; creatinine clearance 116 +/- 24 vs. 128 +/- 68 ml/min; median (range) proteinuria 0.7 (0.1-1.0) vs. 0.5 (0.07-3.9) g/24 h (P = NS for all). This cohort of 11 patients showed the same interstitial changes as the whole group. Between-group analysis showed that the change in interstitial volume fraction was significantly greater in the PO compared with PE group (0.10 +/- 0.07 vs. -0.001 +/- 0.04, P = 0.020). There were no significant changes in proteinuria or glomerular structural parameters (mesangial volume fraction PO 0.40 +/- 0.17 to 0.42 +/- 0.21; PE 0.29 +/- 0.08 to 0.28 +/- 0.14) in either treatment group.

CONCLUSIONS

Interstitial changes appear to be more sensitive to ACE inhibition than glomerulopathy. Larger patient groups and longer treatment periods are necessary in order to detect any possible impact of ACE inhibition on the glomerular changes in Type 2 diabetes mellitus.

Long-term comparison between perindopril and nifedipine in normotensive patients with type 1 diabetes and microalbuminuria

The aim of this study is to compare the efficacy of an angiotensin-converting enzyme inhibitor with a dihydropyridine calcium channel blocker in preventing progression to macroalbuminuria and/or a decline in renal function in normotensive patients with type 1 diabetes and microalbuminuria. Forty-two patients were randomized to treatment with either perindopril, slow-release nifedipine, or placebo. In the first 3 months, drug dosage was titrated to achieve a decrease in diastolic blood pressure of at least 5 mm HG: Thirty-three patients had a minimum of 24 months' data, and 25 patients were followed up beyond 36 months (mean, 67 +/- 4 months). Patients were studied every 3 months and at the end of the treatment period; those who remained normotensive discontinued therapy and were followed up for an additional 3 months. Baseline geometric mean albumin excretion rates (AERs) were as follows: perindopril, 66 microg/min; nifedipine, 59 microg/min; and placebo, 66 microg/min. During the first 3 years, 7 of the perindopril-treated but none of the placebo or nifedipine-treated patients reverted to normoalbuminuria (P < 0.01). Median AERs at 3 years of treatment in each group were 23 microg/min for perindopril, 122 microg/min for nifedipine, and 112 microg/min for placebo patients (P < 0.01). In patients with more than 3 years' follow-up, median AERs decreased by 45% in the first year and then stabilized in the perindopril group, but increased by 17.6% in the nifedipine group and 27.6% in the placebo group (P < 0.03) in the first year, then increased progressively. In these same patients, there was a significant decline in glomerular filtration rate in the nifedipine group (-7.8 +/- 1.8 mL/min/1.73 m(2)/y), but not in the other two groups (perindopril, -1.0 +/- 1.2 mL/min/1.73 m(2)/y; placebo, -1.3 +/- 1.1 mL/min/1.73 m(2)/y; P = 0.004). At the end of the study, cessation of treatment for 3 months was associated with a doubling of AERs in the perindopril-treated group, but no change in the other two groups (P < 0.001). In conclusion, long-term perindopril therapy is more effective than nifedipine or placebo in delaying the progression of diabetic nephropathy and reducing AER to the normoalbuminuric range (<20 microg/min) in normotensive patients with type 1 diabetes and microalbuminuria.

Effect of 3 years of antihypertensive therapy on renal structure in type 1 diabetic patients with albuminuria: the European Study for the Prevention of Renal Disease in Type 1 Diabetes (ESPRIT)

In the treatment of diabetic nephropathy, ACE inhibitor therapy reduces albumin excretion and slows the rate of decline in glomerular filtration rate (GFR). Our study was designed to investigate whether these effects lay in amelioration of the underlying glomerular structural abnormalities. A total of 54 type 1 diabetic patients with albuminuria and blood pressure (BP) <150/90 mmHg were randomized to receive 10 mg enalapril once daily, 10 mg nifedipine retard twice daily, or placebo in a multicenter double-blind study of 3 years' duration. Renal biopsy was performed at baseline and follow-up, and tissue was analyzed by standard morphometric methods. BP, GFR, albumin excretion rate (AER), and HbA1c were measured every 6 months. Enalapril lowered AER after 6 months by 26% (P < 0.05); however, this reduction was not sustained at 3 years. There was no significant effect of nifedipine or placebo on AER. GFR decreased by a similar average rate of 4.1 ml x min(-1) x year(-1) (95% CI 2.6-5.6) in all three groups. BP and HbA1c were unchanged throughout the study in all groups. At baseline, nearly all biopsies showed classic appearances of diabetic glomerulopathy. There was no detectable effect of enalapril compared with either nifedipine or placebo on renal structure over 3 years. However, we found that patients with increased AER have established glomerulopathy and a progressive average decline in GFR of 4.1 ml x min(-1) x year(-1) in the absence of overt hypertension, and baseline AER appeared predictive of subsequent mesangial volume fraction (r = 0.20, P = 0.0018). In this small cohort of nonhypertensive patients studied for 3 years, disease evolution appears unaffected by treatment with either enalapril or nifedipine.

Effect of ACE inhibitors in diabetic and nondiabetic chronic renal disease: a systematic overview of randomized placebo-controlled trials

Clinical trials have shown the beneficial effects of angiotensin-converting enzyme (ACE) inhibitors in delaying the progression of diabetic renal disease. There is less evidence from primary clinical trials of nondiabetic renal disease. We performed an updated meta-analysis to determine the efficacy of ACE inhibitors in slowing the progression of renal disease over a broad range of functional renal impairment. We included published and unpublished randomized, placebo-controlled, parallel trials with at least 1 year of follow-up available from January 1970 to June 1999. In nine trials of subjects with diabetic nephropathy and microalbuminuria, the relative risk for developing macroalbuminuria was 0.35 (95% confidence interval [CI], 0.24 to 0.53) for individuals treated with an ACE inhibitor compared with placebo. In seven trials of subjects with overt proteinuria and renal insufficiency from a variety of causes (30% diabetes, 70% nondiabetes), the relative risk for doubling of serum creatinine concentration or developing end-stage renal disease was 0.60 (95% CI, 0.49 to 0.73) for individuals treated with an ACE inhibitor compared with placebo. Treatment of individuals with chronic renal insufficiency with ACE inhibitors delays the progression of disease compared with placebo across a spectrum of disease causes and renal dysfunction.

The case for combining angiotensin-converting enzyme inhibitors and calcium-channel blockers

Tight blood pressure control among diabetic and nondiabetic patients with hypertension is perhaps the single most effective intervention used to delay progression to end-stage renal disease (ESRD). The renoprotective actions of angiotensin-converting enzyme (ACE) inhibitors in patients with diabetic and hypertensive nephropathy is well established. Drugs of this class fairly uniformly reduce glomerulosclerosis, delay the deterioration in renal function, and improve proteinuria, a predictive surrogate marker for renal injury. Calcium- channel blockers (CCBs) in the phenylalkylamine (verapamil) and benzothiazepine (diltiazem) classes also improve proteinuria and delay the progression of renal disease in diabetic and nondiabetic hypertensive nephropathy beyond that attributable to blood pressure control. The short-acting dihydropyridine CCBs worsen proteinuria and accelerate renal injury in both animal models and humans with hypertension or diabetes. A very limited number of studies in animals or humans with hypertension or diabetes have demonstrated at least an additive renoprotective effect when the combination of ACE inhibitors and nondihydropyridine CCBs has been compared with each agent administered as monotherapy. Because patients with impaired renal function and either hypertension or diabetes appear to benefit from aggressive blood pressure reduction, many of these patients will require two or more drugs to achieve the currently recommended blood pressure goals. Combinations of ACE inhibitor and CCB are attractive because they may provide better blood pressure control, appear to be better tolerated with fewer side effects than either drug alone, and may exert a greater renoprotective effect in patients at risk for renal failure than either an ACE inhibitor or a CCB.