Evolving strategies for renoprotection: diabetic nephropathy

[Blood pressure goals in chronic kidney disease : What is the optimal blood pressure for inhibition of progression and risk reduction?]

Well-controlled blood pressure is an essential factor in inhibiting the progression of renal failure and also in controlling cardiovascular mortality and morbidity. For decades there has been an intensive search for the optimal blood pressure target values in order to reduce the progression of renal insufficiency to a physiological level as far as possible. In the last few decades, very different target blood pressure values have been defined, which time and again contribute more to confusion than clarity in everyday clinical practice. The present work considers the relevant guidelines; it analyzes the basis on which the sometimes widely varying guidelines were created. All guidelines agree that blood pressure control with a target of less than 140 mm Hg systolic should be achieved in patients with impaired renal function. The European guidelines recommend aiming for a target of 130-140 mm Hg systolic. The American guidelines go one step further and specify a systolic blood pressure target of less than 130 mm Hg. The Kidney Disease: Improving Global Outcomes (KDIGO) organization is even more ambitious. It recommends a blood pressure target of less than 120 mm Hg, whereby in contrast to the European and American guidelines, the level of evidence required in the guidelines is considered to be very weak and the goals should also be achieved if automated, standardized blood pressure measurement is carried out, which is rarely available in everyday practice and may not be feasible. The present overview discusses the arguments for lowering blood pressure with different goals and presents the evidence. Of course, the blood pressure goals in the presence or absence of albuminuria should also be considered.

Identification of nephropathy predictors in urine from children with a recent diagnosis of type 1 diabetes

Despite research progresses, the chance to accurately predict the risk for diabetic nephropathy (DN) is still poor. So far, the first evidence of DN is micro-albuminuria, which is detected only 10-20 years after the onset of diabetes. Our goal is to develop new predictive tools of nephropathy starting from urine, which can be easily obtained using noninvasive procedures and it is directly related to kidney. Since it is reasonable to suppose that, in predisposed patients, the mechanisms leading to nephropathy start acting since the diabetes onset, urine from children with recent diagnosis of type 1 diabetes was subjected to proteomic analysis in comparison to age-matched controls. Targeted confirmation was performed on children with a longer history of diabetes using Western Blotting and applying a urinary lipidomic approach. To definitively understand whether the observed alterations could be related to diabetic nephropathy, urine from diabetic adults with or without albuminuria was also examined. For the first time, lipid metabolisms of prostaglandin and ceramide, which are significantly and specifically modified in association with DN, are shown to be already altered in children with a recent diabetes diagnosis. Future studies on larger cohorts are needed to improve the validity and generalizability of these findings. Data are available via ProteomeXchange with identifier PXD011183 Submission details: Project Name: Urinary proteomics by 2DE and LC-MS/MS. Project accession: PXD011183 Project DOI: https://doi.org/10.6019/PXD011183 SIGNIFICANCE: Nephropathy is a very common diabetic complication. Once established, its progression can only be slowed down but full control or remission is achieved in very few cases, thus posing a large burden on worldwide health. The first evidence of diabetic nephropathy (DN) is micro-albuminuria, but only 30% of patients with micro-albuminuria progress to proteinuria, while in some patients it spontaneously reverts to normo-albuminuria. Thus, there is clear need for biomarkers that can accurately predict the risk to develop DN. Herein, by applying proteomic and lipidomic approaches on urine samples, we show that alteration of prostaglandin and ceramide metabolisms specifically occurs in association with DN. Interestingly, we demonstrate that the modification of these metabolic pathways is an early event in diabetic patients, suggesting the identified changed proteins as possible predictive biomarkers of diabetes-induced renal function decline.

Analysis of emergency Department Frequentation among patients with advanced CKD (chronic kidney disease): Lessons to optimise scheduled renal replacement therapy initiation

The decision to initiate renal replacement therapy (RRT) implies a wide margin of uncertainty. Glomerular filtration rate (GFR) tells us the magnitude of renal damage. Proteinuria indicates the speed of progression. However, nowadays more than 50% of patients are still initiating RRT hastily, and it is life threatening.

HYPOTHESIS

By analysing Emergency Department (ED) frequentation and causes of a hurried initiation, we can better schedule the timing of the start of RRT.

METHOD

Retrospective and observational study of all CKD patients in our outpatient clinic. ED frequentation and hospitalisation (Hos) time were reviewed during a 12-month period. We analysed: 1) time at risk, purpose (modality of RRT), previous comorbidity; 2) causes of ED frequentation and Hos; 3) type of initiation: «scheduled» vs. «non-scheduled», and within these «non-planned» vs. «potentially planned».

RESULTS

Of a total of 267 patients (time at risk 63.987 days, 70±13 years, 67% males, 38% diabetics), 68 (25%) patients came to hospital on 97 occasions: 39 only ED, 46 ED+Hos and 12 only Hos. ED frequentation was one patient every 4.3 days, and bed occupation was almost 3 per day. Main causes: 47% cardiopulmonary (1/3 heart failure), 11% vascular peripheral+cerebral, 11% gastrointestinal: 8/11 due to bleeding (all with anticoagulants/antiplatelet agents). Thirty-one (12%) patients initiated RRT: of these, 14 (45%) were scheduled (6 PD, 6 HD, and 2 living donor RTx), and 17 (55%) were not scheduled or were rushed, all with venous central catheter. Following the objectives of this study, the non-scheduled group were itemised into 2 groups: 9 non-planned (initial indication of conservative management or patient's refusal to undergo dialysis, and diverse social circumstances not controllable by the nephrologist) and 8 were considered potentially planned (6 heart failure, one gastrointestinal bleeding and one peripheral vascular complication). This last group (potentially planned), when compared with the 14 patients who started treatment in a scheduled manner, had significant differences in that they were older, with more previous cardiac events, and GFR almost double that of the other group. All of them started treatment in the ED.

CONCLUSION

This analysis provides us with knowledge on those patients who may benefit from an earlier preparation in RRT. We suggest that patients with previous cardiac events, especially with a risk of gastrointestinal bleeding, should start the preparation for RRT even with GFR rates of 20^-25ml/min. In spite of the retrospective nature of this study, and taking into account the difficulties of carrying out clinical trials in this population, we propose this suggestion as complementary to the current recommendations for a scheduled start using this technique.

Clinical Trajectories, Healthcare Resource Use, and Costs of Diabetic Nephropathy Among Patients with Type 2 Diabetes: A Latent Class Analysis

INTRODUCTION

Patients with type 2 diabetes mellitus (T2DM) are clinically heterogeneous in terms of disease severity, treatment, and comorbidities, potentially resulting in differential diabetic nephropathy (DN) progression courses. In this exploratory study we used latent class analysis (LCA) to identify patient groups with distinct clinical profiles of T2DM severity and explored the association between disease severity, DN progression or reversal, and healthcare resource use (HRU) and costs.

METHODS

Latent class analysis was used to group adults with ≥  2 medical claims with a diagnosis of T2DM and ≥ 2 urine albumin tests within the Truven MarketScan database (2004-2014), based on T2DM-related complications, comorbidities, and therapies. DN severity categories (normoalbuminuria, moderately increased albuminuria, and severely increased albuminuria) were determined based on urine albumin measure. The risks of DN progression and reversal (change to a more/less severe DN category) were compared among all identified latent classes using Kaplan-Meier analyses and log-rank tests. All-cause and DN-related costs and HRU were assessed and compared during the study period among the identified latent classes.

RESULTS

Four clinically distinct profiles were identified among the 23,235 eligible patients: low comorbidity/low treatment (46.5%), low comorbidity/high treatment (29.0%), moderate comorbidity/high insulin use (9.7%), and high comorbidity/moderate treatment (14.8%). The 5-year DN progression rates for these clinically distinct profiles were 11.8, 18, 16.5, and 27.7%, respectively. Compared with the low comorbidity/low treatment group, all other groups were associated with an increased risk of DN progression (all p < 0.001). Increasing comorbidity was significantly associated with higher all-cause and DN-related HRU and costs, primarily driven by higher pharmacy and inpatient costs.

CONCLUSION

Patients with T2DM who have more comorbidities experienced higher rates of DN progression and HRU and incurred higher healthcare costs compared with patients with low comorbidity profiles. Future prospective studies are needed to confirm the significance of these groups on DN progression, HRU, and costs.

FUNDING

Takeda Development Center Americas, Inc.

MicroRNA-25 inhibits high glucose-induced apoptosis in renal tubular epithelial cells via PTEN/AKT pathway

Diabetic nephropathy (DN) has become the major cause of end-stage renal disease (ESRD). It has been demonstrated that apoptosis of renal tubular epithelial cells induced by hyperglycemia contributes to the pathogenesis of DN. Recent researches have corroborated the critical roles of microRNAs (miRNAs) in the apoptosis of various types of cells including renal tubular epithelial cells. However, the eff ; ;ect of miRNAs on the hyperglycemia-induced apoptosis of renal tubular epithelial cells remains unclear. The aim of this study is to explore the eff ; ;ect of miRNAs on the hyperglycemia-induced apoptosis of renal tubular epithelial cells and its molecular mechanism. Using a miRNA microarray, miRNAs putatively associated with DN were examined in renal biopsy tissue samples from DN patients and healthy controls. Validation analysis of miR-25 level in serum samples and renal biopsy tissue samples was performed using quantitative reverse transcription PCR (qRT-PCR). Then, gain- and loss- of function experiments were performed to determine the protective roles of miR-25 in high glucose-induced damage to renal tubular epithelial cells. Furthermore, the target gene of miR-25 and the downstream signaling pathway were also investigated. Microarray analysis and qRT-PCR revealed that miR-25 was significantly downregulated in renal biopsy tissue and serum samples from DN patients. We also observed that an inverse relationship between serum miR-25 level and proteinuria in DN patients. Meanwhile, miR-25 was decreased in human kidney (HK-2) cells subjected to HG treatment in a time dependent manner. Its overexpression reduced production of reactive oxygen species (ROS), suppressed cell apoptosis in HG-induced cell damage model, which was coupled with the decreased expression of cleaved caspase-3 and activity of caspase-3. Subsequent analyses demonstrated that phosphatase and tensin homolog deleted on chromosome ten (PTEN) was a direct and functional target of miR-25, which was validated by the dual luciferase reporter assay. Most importantly, the overexpression of PTEN effectively reversed the protective effects of miR-25 mimics on renal tubular epithelial cell injury. We also found that the anti-apoptotic effects of miR-25 are dependent on the activation of PTEN/Akt pathway. In addition, we observed that PTEN was upregulated in renal biopsy tissue samples from patients with DN, and an inverse relationship was found between PTEN and miR-25 expression, suggesting that miR-25 may exert its function through regulation of PTEN in DN. Taken together, our study proved that overexpression of miR-25 could ameliorate HG-induced oxidative stress and apoptosis in renal tubular epithelial cells through activation of PTEN/AKT pathway, suggesting that overexpression of miR-25 might provide a potential therapeutic approach for DN.

Contrast-enhanced ultrasonography is a valid technique for the assessment of renal microvascular perfusion dysfunction in diabetic Goto-Kakizaki rats

AIM

To evaluate the reliability of contrast-enhanced ultrasonography (CEUS) for the detection of renal microvascular blood perfusion in a type 2 diabetic Goto-Kakizaki (GK) rat model.

METHODS

Male GK and Wistar rats at the age of 4, 12 and 20 weeks (n=10, respectively) were used for the study. Real-time and haemodynamic imaging of the renal cortex was performed using CEUS with SonoVue. Outage time-intensity curves (TICs) were applied for the analysis of basic intensity, slope rates of the ascending (S1) and descending curves (S2), time to peak (TTP), half time of peak descending (HDT), peak intensity (PI), and total area under the curve (AUC). Immunohistochemical staining for endothelial cells (ECs) was performed using the CD34 monoclonal antibody for the quantification of microvessel density and distribution.

RESULTS

Images of the renal cortex microvascular beds after injection of SonoVue in the rats were rapidly and clearly displayed, and it is easy to differentiate the enhanced and faded images of renal perfusion. The TICs of the GK rats were much wider than the controls; however, no significant changes in PI were found in all aged rats. Ultrasonographic quantitative analysis revealed a decrease in S1 and S2, and an increase in TTP, HDT and AUC in the 12- and 20-week-old GK rats compared with the controls (P<0.05). Moreover, the 20-week-old GK rats had much lower glomerular density and smaller distribution area of CD34-positive ECs, which was in parallel with more severe proteinuria, GBM thickening, glomerulosclerosis and interstitial vascular damages (P<0.05). Interestingly, negative correlations between AUC and glomerular microvessel density or distribution were detected, respectively (P<0.05).

CONCLUSIONS

Contrast-enhanced ultrasonography is a valid technique for the real-time and dynamic assessment of renal cortex microvascular perfusion and haemodynamic characterization in GK rats.

Novel effective drugs for diabetic kidney disease? or not?

INTRODUCTION

Diabetes mellitus is increasingly common worldwide and is expected to affect 592 million people by 2035. The kidney is often involved. A key goal in treating diabetes is to reduce the risk of development of kidney disease and, if kidney disease is already present, to delay the progression to end-stage renal disease (ESRD). This represents a social and ethical issue, as a significant proportion of patients reaching ESRD in developing countries do not have access to renal replacement therapy.

AREAS COVERED

The present review focuses on novel therapeutic approaches for diabetic nephropathy (DN), implemented on the basis of recent insights on its pathophysiology, which might complement the effects of single inhibition of the renin-angiotensin-aldosterone system (RAAS), the cornerstone of renoprotective interventions in diabetes, along with glycemic and blood pressure control.

EXPERT OPINION

Although a plethora of new treatment options has arisen from experimental studies, the number of novel renoprotective molecules successfully implemented in clinical practice over the last two decades is disappointingly low. Thus, new investigational strategies and diagnostic tools - including the appropriate choice of relevant renal end points and the study of urinary proteome of patients - will be as important as new therapeutic interventions to fight DN. Finally, in spite of huge financial interests in replacing the less expensive ACE inhibitors and angiotensin II receptor blockers with newer drugs, any future therapeutic approach has to be tested on top of - rather than instead of - optimal RAAS blockade.

NFAT2 inhibitor ameliorates diabetic nephropathy and podocyte injury in db/db mice

BACKGROUND AND PURPOSE

Podocyte injury plays a key role in the development of diabetic nephropathy (DN). We have recently shown that 11R-VIVIT, an inhibitor of cell-permeable nuclear factor of activated T-cells (NFAT), attenuates podocyte apoptosis induced by high glucose in vitro. However, it is not known whether 11R-VIVIT has a protective effect on DN, especially podocyte injury, under in vivo diabetic conditions. Hence, we examined the renoprotective effects of 11R-VIVIT in diabetic db/db mice and the possible mechanisms underlying its protective effects on podocyte injury in vivo and in vitro.

EXPERIMENTAL APPROACH

Type 2 diabetic db/db mice received i.p. injections of 11R-VIVIT (1 mg·kg(-1)) three times a week and were killed after 8 weeks. Immortalized mouse podocytes were cultured under different experimental conditions.

KEY RESULTS

11R-VIVIT treatment markedly attenuated the albuminuria in diabetic db/db mice and also alleviated mesangial matrix expansion and podocyte injury. However, body weight, food and water intake, and glucose levels were unaffected. It also attenuated the increased NFAT2 activation and enhanced urokinase-type plasminogen activator receptor (uPA receptor) expression in glomerulor podocytes. In cultured podocytes, the increased nuclear accumulation of NFAT2 and uPA receptor expression induced by high glucose treatment was prevented by 11R-VIVIT or NFAT2-knockdown; this was accompanied by improvements in the filtration barrier function of the podocyte monolayer.

CONCLUSIONS AND IMPLICATIONS

The NFAT inhibitor 11R-VIVIT might be a useful therapeutic strategy for protecting podocytes and treating DN. The calcinerin/NFAT2/uPA receptor signalling pathway should be exploited as a therapeutic target for protecting podocytes from injury in DN.

NFAT2 mediates high glucose-induced glomerular podocyte apoptosis through increased Bax expression

BACKGROUND

Hyperglycemia promotes podocyte apoptosis and plays a key role in the pathogenesis of diabetic nephropathy. However, the mechanisms that mediate hyperglycemia-induced podocyte apoptosis is still far from being fully understood. Recent studies reported that high glucose activate nuclear factor of activated T cells (NFAT) in vascular smooth muscle or pancreatic β-cells. Here, we sought to determine if hyperglycemia activates NFAT2 in cultured podocyte and whether this leads to podocyte apoptosis. Meanwhile, we also further explore the mechanisms of NFAT2 activation and NFAT2 mediates high glucose-induced podocyte apoptosis.

METHODS

Immortalized mouse podocytes were cultured in media containing normal glucose (NG), or high glucose (HG) or HG plus cyclosporine A (a pharmacological inhibitor of calcinerin) or 11R-VIVIT (a special inhibitor of NFAT2). The activation of NFAT2 in podocytes was detected by western blotting and immunofluorescence assay. The role of NFAT2 in hyperglycemia-induced podocyte apoptosis was further evaluated by observing the inhibition of NFAT2 activation by 11R-VIVIT using flow cytometer. Intracellular Ca(2+) was monitored in HG-treated podcocytes using Fluo-3/AM. The mRNA and protein expression of apoptosis gene Bax were measured by real time-qPCR and western blotting.

RESULTS

HG stimulation activated NFAT2 in a time- and dose-dependent manner in cultured podocytes. Pretreatment with cyclosporine A (500nM) or 11R-VIVIT (100nM) completely blocked NFAT2 nuclear accumulation. Meanwhile, the apoptosis effects induced by HG were also abrogated by concomitant treatment with 11R-VIVIT in cultured podocytes. We further found that HG also increased [Ca(2+)]i, leading to activation of calcineurin, and subsequent increased nuclear accumulation of NFAT2 and Bax expression in cultured podocytes.

CONCLUSION

Our results identify a new finding that HG-induced podocyte apoptosis is mediated by calcineurin/NFAT2/Bax signaling pathway, which may present a promising target for therapeutic intervention.

Inflammatory and endothelial dysfunction markers and proteinuria in persons with type 1 diabetes mellitus

OBJECTIVE

We examined the relationship of inflammatory and endothelial dysfunction markers with the prevalence and incidence of gross proteinuria (GP) in persons with type 1 diabetes mellitus.

DESIGN

A longitudinal population-based cohort of persons with type 1 diabetes mellitus was followed from 1990-1992 through 2005-2007.

METHODS

Prevalence and 15-year cumulative incidence of GP were defined as outcome variables. Serum high-sensitivity C-reactive protein (hsCRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), soluble vascular cell adhesion molecule-1 (VCAM-1), soluble intercellular adhesion molecule-1, and serum total homocysteine were measured. Multivariate logistic and discrete linear logistic regression modeling was used for data analysis.

RESULTS

After controlling for duration of diabetes and other confounding factors, TNF-alpha (odds ratio (OR) 3.64; 95% confidence interval (CI) 2.33, 5.70), IL-6 (OR 1.41; 95% CI 1.06, 1.88), VCAM-1 (OR 13.35; 95% CI 5.39, 33.07), and homocysteine (OR 2.98; 95% CI 1.73, 5.16) were associated with prevalent proteinuria. Only hsCRP (OR 1.47; 95% CI 1.02, 2.11) was associated with incident proteinuria.

CONCLUSIONS

These findings suggest a role of inflammation and endothelial dysfunction as markers and contributors of the development of diabetic nephropathy in persons with type 1 diabetes mellitus.

Lowering blood pressure blocks mesangiolysis and mesangial nodules, but not tubulointerstitial injury, in diabetic eNOS knockout mice

Recently, we and others reported that diabetic endothelial nitric oxide synthase knockout (eNOSKO) mice develop advanced glomerular lesions that include mesangiolysis and nodular lesions. Interestingly, insulin treatment lowered blood pressure and prevented renal lesions, raising the question as to whether these beneficial effects of insulin were due to its ability to lower either high glucose levels or high blood pressure. We, therefore, examined the effect of lowering blood pressure using hydralazine in this diabetic eNOSKO mouse model. Hydralazine treatment significantly blocked the development of mesangiolysis and microaneurysms, whereas tubulointerstitial injury was not prevented in these mice. Additionally, hydralazine did not reduce expression levels of either tubulointerstitial thrombospondin-1 or transforming growth factor-beta despite controlling blood pressure. On the other hand, the critical role of high glucose levels on the development of tubulointerstitial injury was suggested by the observation that serum glucose levels were correlated with tubulointerstitial injury, as well as with the expression levels of both transforming growth factor-beta and thrombospondin-1. Importantly, controlling blood glucose with insulin completely blocked tubulointerstitial injury in diabetic eNOSKO mice. These data suggest that glomerular injury is dependent on systemic blood pressure, whereas hyperglycemia may have a more important role in tubulointerstitial injury, possibly due to the stimulation of the thrombospondin-1-transforming growth factor-beta pathway in diabetic eNOSKO mice. This study could provide insights into the pathogenesis of advanced diabetic nephropathy in the presence of endothelial dysfunction.

Investigational drugs for diabetic nephropathy

BACKGROUND

Diabetic nephropathy is one of the main causes of end-stage renal disease (ESRD) and is associated with elevated cardiovascular morbidity and mortality.

OBJECTIVE

Current renoprotective treatments for diabetic nephropathy include strict glycemic and optimal blood pressure control, proteinuria/albuminuria reduction and the use of renin-angiotensin-aldosterone system (RAAS) blocking agents. However, the renoprotection provided by these treatments is only partial, calling for more effective approaches.

METHODS

This review examines emerging strategies for the treatment of diabetic nephropathy, including aggressive RAAS blockade, statins, glitazones, ruboxistaurin, and other promising agents.

RESULTS/CONCLUSIONS

In diabetic patients with overt nephropathy, multipharmacological interventions represent a promising way to prevent progression to ESRD. Results of ongoing trials are needed to establish whether the current standard of care of diabetic nephropathy might be improved with these new strategies.

The role of renin-angiotensin-aldosterone system-based therapy in diabetes prevention and cardiovascular and renal protection

Hypertension increases the risk of type 2 diabetes mellitus (T2DM) and cardiovascular disease. In addition to lowering blood pressure, blockade of the renin-angiotensin-aldosterone system (RAAS) reduces the risk of new-onset T2DM and offers renal protection. Using a MEDLINE search, we identified multiple trials that reported the incidence of T2DM in patients taking inhibitors of RAAS. In this review, we will discuss the RAAS as a potential target in diabetes prevention and the mechanisms through which inhibitors of this system achieve such an important effect. We will also shed light on the beneficial cardiovascular and renal effects of RAAS blockade. Although multiple studies have demonstrated that inhibitors of RAAS, especially angiotensin-converting enzyme inhibitors and angiotensin receptor blockers, can reduce the incidence of T2DM, randomized controlled studies are still needed to further elucidate their exact role in diabetes prevention.

Inhibition of the renin-angiotensin system and chronic kidney disease

Chronic kidney disease (CKD), a major worldwide public-health problem which affects about 10% of the population, has an increased annual incidence rate of about 5-8%. This increased incidence is mainly due to type 2 diabetes and hypertension and the increasing incidence of elderly patients with CKD. Although the progression to end-stage renal failure (ESRF) is mainly based upon the underlying disease, comorbid conditions such as an initial low renal function, severe proteinuria, and high levels of blood pressure also play important roles in the development of ESRF. Since experimental and clinical evidence suggest that angiotensin II plays a central role in the progression of CKD, pharmacological inhibition of the renin-angiotensin-aldosteron system (RAAS) with angiotensin converting enzyme inhibitors or angiotensin II receptor antagonists has been suggested as first-line treatment for hypertension and prevention of ESRF in these patients. Aliskiren, a novel renin inhibitor is also a promising medical intervention. However, independently of the category of the drugs used, low target blood pressure levels seem to be equally or more important for the delay or prevention of CKD. In this review the results of studies with pharmacological inhibition of the RAAS in patients with diabetic and nondiabetic nephropathy is discussed.

Anemia as a risk factor for chronic kidney disease

Chronic kidney disease (CKD) is an important and leading cause of end-stage renal disease (ESRD) and moreover, plays a role in the morbidity and mortality due to cardiovascular disease, infection, and cancer. Anemia develops during the early stages of CKD and is common in patients with ESRD. Anemia is an important cause of left ventricular hypertrophy and congestive heart failure. Correction of anemia by erthyropoiesis-stimulating agent (ESA) has been shown to improve survival in patients with congestive heart failure. Anemia is counted as one of the non-conventional risk factors associated with CKD. Hypoxia is one of the common mechanisms of CKD progression. Treatment by ESA is expected to improve quality of life, survival, and prevent the CKD progression. Several clinical studies have shown the beneficial effects of anemia correction on renal outcomes. However, recent prospective trials both in ESRD and in CKD stages 3 and 4 failed to confirm the beneficial effects of correcting anemia on survival. Similarly, treatment of other risk factors such as hyperlipidemia by statin showed no improvement in the survival of dialysis patients. Given the high prevalence of anemia in ESRD and untoward effects of anemia in CKD stages 3 and 4, appropriate and timely intervention on renal anemia using ESA is required for practicing nephrologists and others involved in the care of high-risk population. Lessons from the recent studies are to correct renal anemia (hemoglobin <10 g/dl not hemoglobin > or =13 g/dl). Early intervention for renal anemia is a part of the treatment option in the prevention clinic. In this study, clinical significance of anemia management in patients with CKD is discussed.

Rationale for and study design of the sulodexide trials in Type 2 diabetic, hypertensive patients with microalbuminuria or overt nephropathy

BACKGROUND

Patients with Type 2 diabetes and albuminuria are at high risk to progress to end-stage renal disease (ESRD). Although angiotensin receptor blockers confer renoprotection, many diabetic patients still develop overt nephropathy and reach ESRD. Glycosaminoglycans belong to the same family as heparin and heparinoids. Pilot studies with sulodexide, a glycosaminoglycan, have shown that sulodexide can reduce urinary albumin excretion rates in diabetic patients. No hard renal end-point data are available.

METHODS

Two multicentre, double-masked, randomized placebo controlled trials were designed to study the renoprotective potential of sulodexide. The Sulodexide Microalbuminuria Trial examined the efficacy of sulodexide given over 26 weeks in 1000 patients with Type 2 diabetes, hypertension and microalbuminuria. The Sulodexide Overt Nephropathy Trial examined the efficacy of sulodexide in 2240 patients with Type 2 diabetes, hypertension and proteinuria > or = 900 mg/24 h.

RESULTS

The primary outcome of The Sulodexide Microalbuminuria Trial was (i) conversion to normoalbuminuria and at least a 25% decrease in the urinary albumin creatinine ratio (UACR), or (ii) at least a 50% reduction in UACR. The primary outcome of The Sulodexide Overt Nephropathy Trial was time to a composite end point of doubling of serum creatinine or ESRD.

CONCLUSIONS

The sulodexide nephropathy programme will document whether therapy with sulodexide confers renal protection in Type 2 diabetes and nephropathy.

Trends in incidence of treated end-stage renal disease, overall and by primary renal disease, in persons aged 20?64�years in Europe, Canada and the Asia-Pacific region, 1998?2002

AIMS

To determine if rates of diabetic and non-diabetic end-stage renal disease (ESRD), which had been rising in young and middle-aged adults in all populations up to the mid-1990s, had started to decline, and if so, whether improvement had occurred in respect of each of the principal primary renal diseases causing ESRD.

METHODS

Poisson regression of age- and sex-standardized incidence of ESRD for persons aged 20-64 years in 18 populations from Europe, Canada and the Asia-Pacific region, for 1998-2002.

RESULTS

In persons from 12 European descent (Europid) populations combined, there was a small downward trend in all-cause ESRD (-1.7% per year, P = 0.001), with type 1 diabetic ESRD falling by 7.8% per year (P < 0.001), glomerulonephritic ESRD by 3.1% per year (P = 0.001), and 'all other non-diabetic' ESRD by 2.5% per year (P = 0.02). The reductions in ESRD attributed to hypertensive (-2.2% per year) and polycystic renal disease (-1.5% per year) and unknown diagnosis (-0.2% per year) were not statistically significant. On the other hand, the incidence of type 2 diabetic ESRD rose by 9.9% per year (P < 0.001) in the combined Europid population, although that of (principally type 2) diabetic ESRD remained unchanged in the pooled data from the four non-Europid populations.

CONCLUSION

Recent preventive strategies, probably chiefly modern renoprotective treatment, appear to have been effective for tertiary prevention of ESRD caused by the proteinuric nephropathies other than type 2 diabetic nephropathy, for which the continuing increase in Europid populations represents a failure of prevention and/or a change in the nephropathic potential of type 2 diabetes.

Prescribing angiotensin-converting enzyme inhibitors and angiotensin receptor blockers in chronic kidney disease (Review Article)

In Australia the number of patients developing end-stage kidney disease is growing. Almost 70% of new cases of treated end-stage kidney disease are due to diabetes, hypertension or glomerulonephritis. The majority of these patients have a chronic decline of renal function over many years before dialysis is required, even when the initial insult is no longer present. Hypertension and the degree of proteinuria are the most important determinants for this progression and ample evidence suggests that angiotensin II is the key player in sustaining both hypertension and proteinuria. Angiotensin II mediates not only haemodynamic changes but also profibrotic and pro-inflammatory processes. Blockade of the renin-angiotensin system decreases proteinuria and slows the progression of both diabetic and non-diabetic proteinuric renal disease. Angiotensin-converting enzyme (ACE) inhibitors are first-line therapy in patients with type 1 diabetes mellitus and nephropathy, whereas angiotensin receptor blockers (ARB) are first-line therapy in patients with type 2 diabetes mellitus and microalbuminuria or overt nephropathy. Finally, treatment with ACE inhibitors delays the progression of proteinuric nephropathy in non-diabetic patients. Combination therapy with ACE inhibitors and ARB may allow a more complete blockade of the renin-angiotensin system and clinical trials show that ACE inhibitor-ARB combinations have an additive antiproteinuric effect of up to 40% compared with ACE inhibitor or ARB alone, without additional blood pressure-lowering effect. Finally, it is important to emphasize that progressive lowering of blood pressure to 120 mmHg is associated with improved renal outcome and that this effect is independent of baseline renal function.

Divergent trends in the incidence of end-stage renal disease due to Type 1 and Type 2 diabetes in Europe, Canada and Australia during 1998-2002

AIMS

To describe the variation in geographical distribution of end-stage renal disease (ESRD) due to Type 1 and Type 2 diabetes, and to calculate recent trends in incidence in predominantly white populations.

METHODS

Estimation of age- and sex-standardized incidence of ESRD by type of diabetes, and temporal trends, in population-based data for persons aged 30-44, 45-54 or 55-64 years newly treated for ESRD during 1998-2002 in eight countries or regions of Europe, and Non-Indigenous Canadians and Australians.

RESULTS

The incidence of ESRD due to Type 1 diabetes at age 30-44 years correlated with published rates of childhood-onset insulin dependent diabetes mellitus (P = 0.0025). ESRD due to Type 2 diabetes was uncommon before 45 years of age; in older persons, the highest rates (in Canada and Austria) were five times the lowest rates (in Norway and the Basque region). Rates of ESRD due to Type 1 diabetes fell, per year, by 6.4%[95% confidence interval (CI): 2.1-10.6%) in persons aged 30-44 years, and by 7.7% (95% CI: 2.4-12.7%] in those aged 45-54 years. In contrast, rates of ESRD due to Type 2 diabetes increased annually by 16% (95% CI: 5-28%) in the 30-44-year age group, 11% (95% CI: 6-16%) at 45-54 years, and 9% (95% CI: 5-14%) at 55-64 years.

CONCLUSIONS

Modern prevention has reduced progression of nephropathy to ESRD due to Type 1 diabetes, but the continuing rise of ESRD due to Type 2 diabetes represents a failure of current disease control measures that has serious public health implications.

A randomized trial of low-protein diet in type 1 and in type 2 diabetes mellitus patients with incipient and overt nephropathy

OBJECTIVE

The efficacy of a low-protein diet in the secondary prevention of diabetic nephropathy is not established in patients with type 1 or type 2 diabetes mellitus. To determine whether a low-protein diet slows the decrease in glomerular filtration rate (GFR) and decreases the albumin excretion rate (AER) in diabetic patients with incipient and overt nephropathy, we performed a 2-year prospective, randomized controlled trial comparing the effects of a low-protein diet (0.8 g/kg/day) with a usual-protein diet.

SETTING AND PATIENTS

The study was conducted in a University hospital and included 63 type 1 and type 2 diabetic patients with either incipient or overt nephropathy and mild renal failure (prestudy GFR, 80 +/- 20 mL/min). The primary outcome measures were decreased in GFR and 24-hour AER.

RESULTS

In the low-protein-diet group, patients were younger (52 +/- 12 versus 63 +/- 9 years old) and more often were type 2 diabetic. During the follow-up period, according to dietary records the low-protein-diet group consumed 16% +/- 3% of total caloric intakes as compared with 19% +/- 4% in the usual-protein-diet group (P < .02), but 24-hour urinary urea excretions did not differ between the two groups. The 2-year GFR decrease was 7 +/- 11 mL/min in the low-protein-diet group and 5 +/- 15 mL/min in the usual-protein-diet group (P = not significant). AER did not increase significantly in the two diet groups during the follow-up period. Blood pressure and glycemic control were similar in the two groups all along the study. The decrease in GFR and AER were also similar in 6 compliant patients according to dietary records and to 24-hour urinary urea excretions from the low-protein-diet group and in 12 patients from the usual-protein-diet group.

CONCLUSIONS

A 2-year low-protein diet did not alter the course of GFR or of AER in diabetic patients with incipient or overt nephropathy receiving renin-angiotensin blockers with strict blood pressure control.

Emerging drugs for diabetic nephropathy

There is an increasing number of patients with diabetes mellitus in many countries. Diabetic kidney disease, one of its microvascular complications, is also increasing markedly and has become a major cause of end stage renal disease worldwide. Intervention for preventing and delaying the development and progression of diabetic kidney disease is not only a medical concern, but also a social issue. Despite extensive efforts, however, medical interventions thus far are not effective enough to prevent the progression of the disease and the development of end stage renal disease. This justifies attempts to develop novel therapeutic approaches for diabetic nephropathy. Recent insights on its pathogenesis and progression have suggested new targets for the specific treatment of this disease. They include aldosterone, aldose reductase, arachidonic acid metabolites, growth factors, advanced glycosylation end-products, peroxisome proliferator-activated receptors and endothelin. Several other biochemical mediators have been targeted in experimental animal models with the goal to prevent diabetic nephropathy progression, but translation to clinics of these experimental achievements are still limited or lacking.

The role of renin-angiotensin-aldosterone system in the progression of chronic kidney disease

The renin-angiotensin-aldosterone system (RAAS) is a well known regulator of blood pressure (BP) and determinant of target-organ damage. It controls fluid and electrolyte balance through coordinated effects on the heart, blood vessels, and Kidneys. Angiotensin II (AII) is the main effector of the RAAS and exerts its vasoconstrictor effect predominantly on the postglomerular arterioles, thereby increasing the glomerular hydraulic pressure and the ultrafiltration of plasma proteins, effects that may contribute to the onset and progression of chronic renal damage. AII may also directly contribute to accelerate renal damage by sustaining cell growth, inflammation, and fibrosis. Interventions that inhibit the activity of the RAAS are renoprotective and may slow or even halt the progression of chronic nephropathies. ACE inhibitors and angiotensin II receptor antagonists can be used in combination to maximize RAAS inhibition and more effectively reduce proteinuria and GFR decline in diabetic and nondiabetic renal disease. Recent evidence suggests that add-on therapy with an aldosterone antagonist may further increase renoprotection, but may also enhance the risk hyperkalemia. Maximized RAAS inhibition, combined with intensified blood pressure control (and metabolic control in diabetics) and amelioration of dyslipidemia in a multimodal approach including lifestyle modifications (Remission Clinic), may achieve remission of proteinuria and renal function stabilization in a substantial proportion of patients with proteinuric renal disease. Ongoing studies will tell whether novel drugs inhibiting the RAAS, such as the renin inhibitors or the vasopeptidase inhibitors, may offer additional benefits to those who do not respond, or only partially respond, to this multimodal regimen.

RAS inhibition in hypertension

Drugs that inhibit the renin-angiotensin system (RAS), namely angiotensin-converting enzyme inhibitors (ACE-I) and angiotensin receptor antagonists (ARA) are gaining increasing popularity as initial medications for the management of hypertensive patients. In the year 2002, ACE-I were the most commonly prescribed drugs for the treatment of hypertension in USA. Although their antihypertensive efficacy as monotherapy is similar to other antihypertensive agents, they have the advantage of better tolerability, limited side effects and a favorable metabolic profile. When compared to other antihypertensive agents (diuretics, beta-adrenergic blockers and calcium antagonists) in large clinical trials, ACE-I and ARA provided no additional advantages regarding improvement in cardiovascular and total mortality. With the exception of the superiority of ARA in prevention of stroke, RAS inhibitors have no advantage over other agents in prevention of other cardiovascular morbid events, namely, heart failure (though ACE-I are superior to calcium antagonists), coronary heart disease and total cardiovascular events. However, there is the possibility that these agents have other benefits beyond blood pressure lowering. At equal degrees of blood pressure reduction, RAS inhibitors prevent or delay the development of diabetes mellitus and provide better end-organ protection, kidneys, blood vessels and the heart when compared with other antihypertensive agents. The combined use of ACE-I and ARA is particularly useful in organ protection. RAS inhibitors are specifically indicated in the treatment of hypertension in patients with impaired left ventricular systolic function, diabetes, proteinuria, impaired kidney function, myocardial infarction, multiple cardiovascular risk factors and possibly elderly patients. The main limitation of the ACE-I is cough and rarely angioedema. Elderly patients or those who are volume depleted or receiving large doses of diuretics or in heart failure are liable to develop hypotensive reaction and/or deterioration in kidney function.

The Role of Glycosaminoglycans and Sulodexide in the Treatment of Diabetic Nephropathy

Diabetic nephropathy occurs in 20-40% of diabetic patients, making it one of the most important causes of end-stage renal disease (ESRD). It has a large impact in terms of associated morbidity and mortality for the individual patient and in terms of costs for healthcare. Several studies have demonstrated that micro- and macroalbuminuria predict cardiovascular morbidity and mortality in patients with diabetes mellitus.Current nephroprotective therapies for diabetic nephropathy include the pursuit of normoglycemia and normotension, and a consensus is emerging that there is a necessity to also achieve as low a level of albuminuria as possible. However, the search for innovative and ancillary approaches to the prevention and treatment of this diabetic complication is warranted since strict metabolic control can be difficult, and sometimes dangerous, to achieve and even diabetic patients responding to ACE inhibitors (ACEIs) or angiotensin II receptor antagonists (angiotensin receptor blockers; ARBs) and metabolic control show progressive renal damage and eventually ESRD. A number of drugs are currently being investigated; glycosaminoglycans are particularly interesting since, in theory, they target the generalized endothelial dysfunction and metabolic defect in matrix and basement membrane synthesis which, according to the Steno hypothesis, are responsible for diabetic nephropathy and macroangiopathy.Treatment with glycosaminoglycans, and with sulodexide in particular, significantly improves albuminuria in type 1 and type 2 diabetic patients with micro- or macroalbuminuria. The albuminuria-lowering effect of sulodexide enhances the effect of ACEI/ARB therapy. Most studies have shown that the effect of sulodexide on albuminuria is sustained, strongly suggesting that favorable chemical and anatomic remodeling is induced by exogenous glycosaminoglycans in renal tisues, as observed in the experimental model.

Development, progression, and regression of microalbuminuria in Japanese patients with type 2 diabetes under tight glycemic and blood pressure control: the Kashiwa study

OBJECTIVE

The goal of this study was to know the fate of albuminuria in Japanese patients with type 2 diabetes under tight blood pressure and glycemic control.

RESEARCH DESIGN AND METHODS

Patients having normoalbuminuria (urinary albumin excretion <30 mg/g creatinine, n = 179) or microalbuminuria (albumin excretion 30-299 mg/g creatinine, n = 94) at baseline have been followed up for 8 years: ratio of men to women was 160/113, the mean age was 58 years, pretreatment HbA(1c) (A1C) was 8.8%, and blood pressure was 136/76 mmHg. A1C <6.5% and blood pressure <130/80 mmHg were targeted, and the A1C of 6.5 +/- 0.7% (mean +/- SD) and blood pressure of 127 +/- 11/72 +/- 6 mmHg have been maintained during the 8 years. Development of microalbuminuria or macroalbuminuria (albumin excretion > or =300 mg/g creatinine) in initially normoalbuminuric patients and progression to macroalbuminuria or regression to normoalbuminuria in initially microalbuminuric patients were assessed at year 8.

RESULTS

Development occurred in 27 (15%) of the normoalbuminuric patients and progression and regression in 16 (17%) and 20 (21%), respectively, of the microalbuminuric patients. Significant independent relationships existed between development and higher achieved mean systolic blood pressure (SBP) and regression and lower achieved mean SBP. In the patients with achieved mean SBP <120 mmHg, development was 3%, progression was 11%, and regression was 44% during 8 years. Prediction for nephropathy by blood pressure and glycemia alone was limited. Nevertheless, albumin excretion at year 8 was positively correlated with achieved mean SBP and baseline albuminuria.

CONCLUSIONS

Development and progression were low and regression was high with SBP of 120 mmHg, provided A1C was maintained at 6.5%.

Anti-inflammatory effects of short-term pioglitazone therapy in men with advanced diabetic nephropathy

Patients with diabetic nephropathy have a high rate of cardiovascular events and mortality. Nontraditional cardiovascular risk factors such as oxidative stress and inflammation are thought to be particularly important in mediating these events. Studies suggest that thiazolidinediones (TZDs) can reduce the level of nontraditional cardiovascular risk in people with or without diabetes mellitus. Whether this benefit occurs in patients with diabetic nephropathy is unknown. I hypothesized that the TZD pioglitazone will mitigate oxidative stress and inflammation compared with glipizide in patients with overt diabetic nephropathy. Markers of oxidative stress (plasma and urine albumin carbonyl and total protein carbonyls and malondialdehyde), inflammation [white blood cell (WBC) count, C-reactive protein (CRP), plasma IL-6, TNF-alpha], and plaque stability [matrix metalloproteinase 9 (MMP-9)] were measured in frozen samples obtained from patients with overt diabetic nephropathy participating in a randomized, open-label, blinded end-point, 16-wk trial with glipizide (n = 22) or pioglitazone (n = 22). Pioglitazone therapy in men with advanced diabetic nephropathy reduced WBC count by 1,125/mul (P < 0.001), CRP by 41% (P = 0.042), IL-6 by 38% (P = 0.009), and MMP-9 by 29% (P = 0.016). Specific differential reductions in WBC count of 1,251/mul (P = 0.009) and reduction in IL-6 of 58% with pioglitazone (P = 0.001) were seen compared with glipizide. There were no statistically significant changes observed with plasma TNF-alpha concentrations or markers of oxidative stress with either hypoglycemic agent. In conclusion, pioglitazone reduces proinflammatory markers in patients with overt diabetic nephropathy, which indicates potentially beneficial effects on overall cardiovascular risk. This surrogate end point needs to be confirmed in trials designed to demonstrate cardiovascular protection.

An update of irbesartan and renin-angiotensin system blockade in diabetic nephropathy

Type 2 diabetes is a chief cause of pathologies such as cardiovascular disease, nephropathy and retinopathy, and its prevalence is increasing worldwide. Development of renal disease can be slowed by tight glycaemic control and treatment of associated hypertension with angiotensin-converting enzyme inhibition, as The Diabetes Control and Complications Trial and the UK Prospective Diabetes Study have demonstrated. Recent clinical trials have supported the use of angiotensin II receptor antagonists in the treatment of diabetic nephropathy, resulting in the approval of new therapeutic indications in the US and Europe. The main goal of this review is to demonstrate how results from the Programme for Irbesartan Mortality and Morbidity Evaluation and other recent studies, based on the effects of renin-angiotensin system blockade, can be appropriate in clinical practice, thus displaying benefits of irbesartan therapy at any stage of renal disease in diabetics.

Comparison of valsartan 160 mg with lisinopril 20 mg, given as monotherapy or in combination with a diuretic, for the treatment of hypertension: the Blood Pressure Reduction and Tolerability of Valsartan in Comparison with Lisinopril (PREVAIL) study

BACKGROUND

The goal of antihypertensive therapy is to provide good blood pressure (BP) control without eliciting adverse effects.

OBJECTIVE

This study compared the risk-benefit profile of the angiotensin II receptor blocker valsartan with that of the angiotensin-converting enzyme inhibitor lisinopril in patients with mild to severe hypertension. The primary objective was to show that the equipotent BP-lowering effect of the valsartan-based treatment is accompanied by a better tolerability profile.

METHODS

This 16-week, randomized, double-blind, parallel-group study was conducted at 88 outpatient centers across Italy. After a 2-week placebo run-in period, patients aged > or = 18 years with mild to severe hypertension (systolic BP [SBP], 160-220 mm Hg; diastolic BP [DBP], 95-110 mm Hg) were eligible. Patients were randomized to receive once-daily, oral, self-administered treatment with valsartan 160-mg capsules or lisinopril 20-mg capsules under double-blind conditions for 4 weeks. Responders continued monotherapy, whereas nonresponders had hydrochlorothiazide 12.5 mg added for the final 12 weeks of the study. The 2 primary variables used to assess the equivalence of therapeutic efficacy of the 2 regimens were sitting SBP and sitting DBP, which were measured at weeks 0 (baseline), 4, 8, and 16. The rate of drug-related adverse events (AEs) was used to assess whether 1 treatment had a better tolerability profile than the other. Tolerability was assessed by collecting information about AEs by means of questioning the patient or physical examination at each visit.

RESULTS

A total of 1213 patients were enrolled (635 men, 578 women; mean [SD] age, 54.5 [10.1] years [range, 28-78 years]). The study was completed by 1100 patients (553 receiving valsartan and 547 receiving lisinopril). Fifty-one patients (8.4%) treated with valsartan and 62 (10.2%) [corrected] treated with lisinopril withdrew, mainly because of AEs (9 [1.5%] and 23 patients [3.8%], respectively). The valsartan- and lisinopril-based treatments were similarly effective in reducing sitting BP, with mean SBP/DBP reductions of 31.2/15.9 mm Hg and 31.4/15.9 mm Hg, respectively. At the end of the study, BP was controlled in 82.6% [corrected] of the patients receiving valsartan and 81.6% of those receiving lisinopril. AEs were experienced by 5.1% of the patients treated with valsartan and 10.7% of those treated with lisinopril (P=.0001), with dry cough observed in 1.0% and 7.2% of patients, respectively (P<0.001).

CONCLUSIONS

Valsartan and lisinopril were both highly effective in controlling BP in these patients with mild to severe hypertension, but valsartan was associated with a significantly reduced risk for AEs, especially cough.

Interpreting incidence trends for treated end-stage renal disease: implications for evaluating disease control in Australia

BACKGROUND

Five sources of change modify trends in incidence of treated end-stage renal disease (ESRD): (i) demography; (ii) disease control, comprising prevention and treatment of progressive kidney disease; (iii) competing risks, which encompass dying from untreated uraemia or non-renal comorbidity; (iv) lead-time bias; and (v) classification bias. Thus, rising crude incidence of treated ESRD may conceal effective disease control when there has been demographic change, lessening competing risks, or the introduction of bias.

METHODS

Age-specific incidences of treated ESRD in Australia were calculated from Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry data by indigenous/non-indigenous status (all causes) and by primary renal disease (non-indigenous only) for two successive decades, 1982-1991 and 1992-2001.

RESULTS

We postulate that less competing risks explained much of the increase in treated ESRD in the elderly and Indigenous Australians. The increase in glomerulonephritic ESRD in non-indigenous Australians could be ascribed mainly to immigration from non-European countries. There was no significant change in incidence of treated ESRD in Indigenous or non-indigenous persons aged less than 25 years, in non-indigenous persons aged 25-64 years for ESRD caused by hereditary polycystic disease or hypertension, or in type 1 diabetics aged over 55 years. End-stage renal disease from analgesic nephropathy had declined. The increase in treated ESRD caused by type 2 diabetic nephropathy appeared to be multifactorial. Lead-time/length bias and less competing risks may have concealed a small favourable trend in other primary renal diseases.

CONCLUSION

Whether recent disease control measures have had an impact on incidence of treated ESRD is not yet certain, but seems more likely than implied by previous reports.

Microalbuminuria in type 2 diabetics: an important, overlooked cardiovascular risk factor

The presence of microalbumin in the urine of persons with type 2 diabetes is perhaps the most important early signal heralding the onset of systemic vasculopathy and associated target organ damage to the brain, the heart, and the kidneys. It is easily measured and, unfortunately, frequently overlooked as a screening tool in clinical medicine. If present, it identifies patients at risk for early cardiovascular death and progressive renal disease. Microalbuminuria also identifies patients who need more rigorous cardiovascular risk management, especially more intensive blood pressure control, preferably below 130/80 mm Hg, and strict attention to glycemic control and lipid levels. Therapeutic strategies to facilitate better blood pressure control and reduce microalbuminuria likely will prove to be the most effective way to retard not only the progression of renal disease but also cardiovascular disease. Consequently, the identification and normalization of urine microalbumin excretion should be an important consideration in patients with diabetes.

Proteinuria, a target for renoprotection in patients with type 2 diabetic nephropathy: Lessons from RENAAL

BACKGROUND

Proteinuria or albuminuria is an established risk marker for progressive renal function loss. Albuminuria can be effectively lowered with antihypertensive drugs that interrupt the renin-angiotensin system (RAS). We investigated whether albuminuria could not only serve as a marker of renal disease, but also function as a monitor of the renoprotective efficacy of RAS intervention by the angiotensin II (Ang II) antagonist, losartan, in patients with diabetic nephropathy.

METHODS

The data from the RENAAL (Reduction in End Points in Noninsulin-Dependent Diabetes Mellitus with the Angiotensin II Antagonist Losartan) study, a double-blind, randomized trial, were used to examine the effects of losartan on the renal outcome [i.e., the primary composite end point of doubling of serum creatinine, end-stage renal disease (ESRD) or death] in 1513 type 2 diabetic patients with nephropathy. We examined the effect of the degree of albuminuria at baseline, initial antiproteinuric response to therapy, and the degree of remaining (residual) albuminuria on renal outcome (either the primary composite end point of RENAAL or ESRD). We also evaluated the contribution to renal protection of the antiproteinuric effect of losartan independently of changes in blood pressure.

RESULTS

Baseline albuminuria is almost linearly related to renal outcome, and is the strongest predictor among all measured well-known baseline risk parameters. After adjusting for baseline risk markers of age, gender, race, weight, smoking, sitting diastolic blood pressure, sitting systolic blood pressure, total cholesterol, serum creatinine, albuminuria, hemoglobin, and hemoglobin A(1c) (HbA(1c)) patients with high baseline albuminuria (> or =3.0 g/g creatinine) showed a 5.2-fold (95% CI 4.3-6.3) increased risk for reaching a renal end point, and a 8.1-fold (95% CI 6.1-10.8) increased risk for progressing to ESRD, compared to the low albuminuria group (<1.5 g/g). The changes in albuminuria in the first 6 months of therapy are roughly linearly related to the degree of long-term renal protection: every 50% reduction in albuminuria in the first 6 months was associated with a reduction in risk of 36% for renal end point and 45% for ESRD during later follow-up. Albuminuria at month 6, designated residual albuminuria, showed a linear relationship with renal outcome, almost identical to the relationship between baseline albuminuria and renal risk. Losartan reduced albuminuria by 28% (95% CI -25% to -36%), while placebo increased albuminuria by 4% (95% CI +8% to -1%) in the first 6 months of therapy. The specific (beyond blood pressure lowering) renoprotective effect of the Ang II antagonist, losartan, in this study is for the major part explained by its antialbuminuric effect (approximately 100% for the renal end point, and 50% for ESRD end point).

CONCLUSION

Albuminuria is the predominant renal risk marker in patients with type 2 diabetic nephropathy on conventional treatment; the higher the albuminuria, the greater the renal risk. Reduction in albuminuria is associated with a proportional effect on renal protection, the greater the reduction the greater the renal protection. The residual albuminuria on therapy (month 6) is as strong a marker of renal outcome as is baseline albuminuria. The antiproteinuric effect of losartan explains a major component of its specific renoprotective effect. In conclusion, albuminuria should be considered a risk marker for progressive loss of renal function in type 2 diabetes with nephropathy, as well as a target for therapy. Reduction of residual albuminuria to the lowest achievable level should be viewed as a goal for future renoprotective treatments.

What is the impact of PRIME on real-life diabetic nephropathy?

Type 2 diabetes is increasing globally and is a major cause of conditions such as cardiovascular disease, retinopathy and nephropathy. The Diabetes Control and Complications Trial and the UK Prospective Diabetes Study demonstrated that the progression of renal disease could be slowed by tight glycaemic control and treating any associated hypertension with angiotensin-converting enzyme inhibition. Recent clinical trials have supported the use of angiotensin II receptor antagonists in the treatment of diabetic nephropathy, resulting in the approval of new therapeutic indications in the United States and Europe. The objective of this review is to demonstrate how results from the Program for Irbesartan Mortality and morbidity Evaluation studies apply to clinical practice, and to show how the benefits of irbesartan therapy can be realised at any stage of renal disease in patients with diabetes.

Proteinuria in diabetic nephropathy: treatment and evolution

Diabetic nephropathy is characterized by increased urinary albumin excretion and loss of renal function. Increased urinary albumin (proteinuria) is a key component of this disease. Previously, its development led to end-stage renal disease with increased mortality and morbidity for diabetic patients versus nondiabetic patients. Several treatment strategies currently exist that can prevent, slow, and even reverse diabetic nephropathy. New trials suggest that a multidisciplinary approach focused on optimizing metabolic and hypertensive control, in addition to the use of angiotensin-converting enzyme inhibitors or angiotensin 2 receptor antagonists, is effective in halting the progression of disease. Screening and implementation of these strategies is needed to reverse the epidemic of diabetic renal disease.

Angiotensin-converting enzyme inhibition or angiotensin receptor blockade in hypertensive diabetics?

Hypertension increases the renal and cardiovascular risks in diabetic patients. The beneficial effects of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers on renal and cardiovascular outcomes are discussed in this paper, with a particular focus on their optimal use in the hypertensive diabetic patient, with or without evidence of renal or cardiovascular disease. Although the mechanism of action of the two drug classes is not entirely similar, there is no evidence of differences in their clinical effects. Importantly, the achieved risk reduction with either drug is not similar across subsets of diabetic patients. Overt nephropathy of type 2 diabetes appears poorly responsive even to maximized renin-angiotensin system inhibition. This urgently calls for new interventions that may decrease renal and cardiovascular risk through other mechanisms than blood pressure lowering alone. Improving the outcome of type 2 diabetics is the major clinical challenge for the beginning of the third millennium.

Lessons from trials in hypertensive type 2 diabetic patients

There is incontrovertible evidence that association of type 2 diabetes with hypertension markedly increases the risk of cardiovascular events, death, and nephropathy. In type 2 diabetes, even blood pressure values usually considered below the threshold for hypertension (ie, 140/90 mm Hg) in nondiabetic subjects represent an additional risk of clinical relevance. Evidence that more intensive blood pressure lowering is beneficial in type 2 diabetes over less intensive lowering is also overwhelming. However, most published trials show the need for combination therapy in the great majority of patients, and even with combination therapy it is difficult to attain the expected goal blood pressure, in particular goal systolic blood pressure. It should be recognized that the systolic blood pressure goal of less than 130 mm Hg is a very difficult one to achieve in diabetics. Evidence of the superiority or inferiority of different drug classes is vague and contradictory. Recent evidence concerning angiotensin II receptor antagonists has shown a significant reduction of cardiovascular events, cardiovascular death, and total mortality when losartan was compared with atenolol, but not when irbesartan was compared with amlodipine. If renal endpoints are considered, evidence of the benefit of angiotensin II receptor antagonists in type 2 diabetes is more robust than that available with angiotensin-converting enzyme inhibitors. Primary prevention of development of microalbuminuria seems to be greatly facilitated by strict blood pressure control. However, by attaining normal blood pressure levels (< 130/80 mm Hg), better preservation of glomerular filtration rate does not seem to be insured.

Serum cystatin C in the aged: relationships with health status

BACKGROUND

Serum cystatin C (Cys C) is claimed to be superior to serum creatinine (Cr) in estimating glomerular filtration rate, but its utility in assessing renal function in the polymorbid elderly needs to be evaluated.

METHODS

In a cross-sectional, community-based survey performed in Lieto in southwestern Finland, Cys C, Cr, and urinary albumin-creatinine ratio (ACR) were measured in 1,260 subjects aged 64 to 100 years. Associations of demographic characteristics and health status factors with levels of Cys C, Cr, and ACR were assessed by means of linear models.

RESULTS

In men, hypertension, coronary heart disease, urinary infection, rheumatoid arthritis, glucocorticoid treatment, older age, and lower functional status were found to be significant predictors of higher Cys C values, whereas hypertension, coronary heart disease, urinary infection, older age, and increasing body mass index (BMI) significantly predicted higher Cr values. Among women, corresponding factors were hypertension, glucocorticoid treatment, age, functional status, and BMI for Cys C and hypertension, BMI, and age for Cr. Diabetes was significantly associated only with ACR. These factors explained 35% of variation in Cys C values in men and 34.5% in women versus only 14.8% and 11.3% for Cr, respectively.

CONCLUSION

Glucocorticoid treatment was recognized as an independent Cys C-increasing factor, presumably nonglomerular. In comparison with Cys C, a considerably greater proportion of total variation in Cr values seems to be explained by extrarenal factors.

Mechanisms by which angiotensin-converting enzyme inhibitors prevent diabetes and cardiovascular disease

Angiotensin-converting enzyme (ACE) inhibitors are the first-line therapeutic agents for treating hypertension in patients with the cardiometabolic syndrome and those with diabetes. ACE inhibitor therapy reduces both microvascular and macrovascular complications in diabetes and appears to improve insulin sensitivity and glucose metabolism. Several recent studies indicate that ACE inhibitor therapy reduces the development of type 2 diabetes in persons with essential hypertension, a population with a high prevalence of insulin resistance. ACE inhibitor therapy has been shown to improve surrogates of cardiovascular disease (eg, vascular compliance, endothelial-derived nitric oxide production, vascular relaxation and plasma markers of inflammation, oxidative stress, and thrombosis) and reduce cardiovascular disease, renal disease progression, and stroke. This article explores potential mechanism by which ACE inhibition reduces the development of diabetes, improves these surrogate markers, and reduces cardiovascular disease and renal disease.

ACE inhibition or angiotensin receptor blockade: which should we use in diabetic patients?

Blockade of the effects of angiotensin II (Ang II) by using an angiotensin-converting enzyme (ACE) inhibitor has been proven to be of value in Type 1 diabetic nephropathy and in non-diabetic renal disease. Evidence in favour of Ang II blockade in Type 2 diabetic patients with renal damage is still lacking for ACE inhibitors (ACE-Is), while recent data indicate that angiotensin receptor blockers (ARBs) could be the drugs of choice in this situation. On the other hand, renal damage from the onset of disease is accompanied by a very significant increment in global cardiovascular risk. This fact, as well as that of simultaneous renal and cardiovascular protection, have to be considered for drug selection. In this sense, ACE-Is have been shown to be the drugs of choice when secondary cardiovascular prevention is required, while the evidence in primary prevention in hypertensive patients has been shown with losartan in the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study. All these facts led to the conclusion that both ACE-Is and ARBs can be considered when both renal and cardiovascular protection are aimed for in Type 2 diabetic patients.

Incidence of retinopathy and nephropathy in youth-onset compared with adult-onset type 2 diabetes

OBJECTIVE

To examine the risk of retinopathy and nephropathy in participants in whom type 2 diabetes was diagnosed in youth (before 20 years of age) compared with those in whom type 2 diabetes was diagnosed at older ages.

RESEARCH DESIGN AND METHODS

Subjects in whom youth-onset or adult-onset diabetes was diagnosed in the longitudinal study of health in the Pima Indians of Arizona were followed for microvascular complications. Diabetes was diagnosed in 178 subjects before 20 years of age (youth), in 1,359 subjects at 20-39 years of age (younger adults), and in 971 subjects at 40-59 years of age (older adults). Incidence rates of diabetic retinopathy diagnosed by direct ophthalmoscopy through dilated pupils and nephropathy (protein-to-creatinine ratio > or =0.5 g/g) were calculated by age at diagnosis.

RESULTS

Over 25 years, nephropathy developed in 35 of the participants with youth-onset type 2 diabetes; this incidence rate was not significantly different from that in patients with adult-onset diabetes (P = 0.77). Incidence rates of retinopathy, however, were significantly lower for the youth-onset group (P = 0.007). Adjusted for sex, glycemia, and blood pressure, risk of retinopathy was lower in patients with youth-onset diabetes than in those with adult-onset diabetes (hazard rate ratio [HRR] 0.42, 95% CI 0.24-0.74, P = 0.003), but risk of nephropathy was not different (HRR 1.2, 95% CI 0.77-1.3, P = 0.38).

CONCLUSIONS

In Pima Indians, the risk of nephropathy as a function of duration of diabetes is similar in all age groups. By contrast, the risk of retinopathy is lower in patients with youth-onset type 2 diabetes.