Statins and renal diseases: from primary prevention to renal replacement therapy

The impact of underlying diseases-related drugs on the chronic kidney disease-associated pruritus in hemodialysis patients

Background

Uremic pruritus or chronic kidney disease-associated pruritus (CKD-aP) is a frequent compromising symptom in end-stage renal disease. Despite the little attention paid to drugs used among hemodialysis (HD) patients, investigating medications used in this population of patients and examining the status of CKD-aP may lead to the identification of medications that improve or worsen the pruritus condition. We aimed to assess the role of underlying diseases-related drugs on CKD-aP in HD patients.

Materials and Methods

We performed a case - control study on HD patients aged over 18 years old. The demographic data and clinical parameters including HD parameters, drug history, dermatologic assessments, and laboratory examination were assessed.

Results

We compared 128 patients with CKD-aP as cases and 109 patients without CKD-aP as controls. Cases were on the longer course of dialysis (44.69 ± 43.24 months for cases vs. 38.87 ± 50.73 months for controls; P = 0.02). In multiple analyses of variables related to CKD-aP, backward LR logistic regression revealed that only atorvastatin (P = 0.036) was considered to be a predictive factor associated with CKD-aP. Thus, the use of atorvastatin reduced the index of CKD-aP (95% confidence interval: 0.256-0.954, odd's Ratio = 0.494).

Conclusion

Atorvastatin was associated with decreased frequencies of CKD-aP among HD patients in our study. This knowledge may guide further clinical trials to evaluate atorvastatin's immunomodulatory and anti-inflammatory effects on the CKD-aP in HD populations.

Effects of atorvastatin on proteinuria of type 2 diabetic nephropathy in patients with history of gestational diabetes mellitus: A clinical study

Background

Gestational diabetes is known as one of the diseases through pregnancy. In the present study, changes in proteinuria after atorvastatin administration among patients with history of gestational diabetes were studied.

Materials and Methods

In this randomized clinical trial, 42 patients were included in the study. Atorvastatin was administered for 21 patients, and 21 patients were designated as control group. Lipid profile, protein, and 24 h urine creatinine (uCr) levels were determined in the beginning and 3 months after intervention. P < 0.05 was considered statistically significant.

Results

Lipid profile in intervention group was enhanced; low-density lipoprotein (LDL) had decreased while triglyceride had not changed and high-density lipoprotein had been increased. There was no statistically significant change in serum Cr, serum urea, estimated glomerular filtration rate, uCr, urine volume, 24-h urine protein level, or urine protein/Cr ratio on both groups during the study; also, there was no statistically significant difference between groups.

Conclusions

Although LDL level decreased after atorvastatin therapy, atorvastatin therapy had no effect on the level of proteinuria or other parameters related to kidney function.

Systemic and renal lipids in kidney disease development and progression

Altered lipid metabolism characterizes proteinuria and chronic kidney diseases. While it is thought that dyslipidemia is a consequence of kidney disease, a large body of clinical and experimental studies support that altered lipid metabolism may contribute to the pathogenesis and progression of kidney disease. In fact, accumulation of renal lipids has been observed in several conditions of genetic and nongenetic origins, linking local fat to the pathogenesis of kidney disease. Statins, which target cholesterol synthesis, have not been proven beneficial to slow the progression of chronic kidney disease. Therefore, other therapeutic strategies to reduce cholesterol accumulation in peripheral organs, such as the kidney, warrant further investigation. Recent advances in the understanding of the biology of high-density lipoprotein (HDL) have revealed that functional HDL, rather than total HDL per se, may protect from both cardiovascular and kidney diseases, strongly supporting a role for altered cholesterol efflux in the pathogenesis of kidney disease. Although the underlying pathophysiological mechanisms responsible for lipid-induced renal damage have yet to be uncovered, several studies suggest novel mechanisms by which cholesterol, free fatty acids, and sphingolipids may affect glomerular and tubular cell function. This review will focus on the clinical and experimental evidence supporting a causative role of lipids in the pathogenesis of proteinuria and kidney disease, with a primary focus on podocytes.

Short-term effects of lovastatin therapy on proteinuria of type 2 diabetic nephropathy: A clinical trial study

Background:

Diabetic nephropathy (DN) is characterized by albuminuria, hypertension, and a progressive decline in glomerular filtration rate. The 3-hydroxy-3-methylglutaryl coenzyme A is a well-known agent that is active in lowering total plasma and low-density lipoprotein cholesterol (LDL-C) levels in cases with hypercholesterolemia. Hence, in this study, proteinuria changes at the beginning and after the withdrawal of lovastatin in patients with type 2 DN (T2DN) were studied.

Materials and Methods:

Lovastatin was administered for thirty male patients with T2DN and then was withdrawn. Twenty-four hours, urine creatinine and protein levels were determined.

Results:

The mean levels of total cholesterol and LDL-C were reduced without any change in the triglyceride (TG) level while the high-density lipoprotein cholesterol (HDL-C) level was increased. There was a reverse linear correlation between the changes in the level of HDL-C and the changes in the level of 24 h urine protein after 90 days of lovastatin therapy (P = 0.007, r = −0.484).

Conclusions:

Short-term 3-month lovastatin therapy has no effect on proteinuria levels in patients with T2DN despite the antihyperlipidemic effects and reverse correlation of proteinuria with HDL-C.

Pravastatin Therapy and Biomarker Changes in Children and Young Adults with Autosomal Dominant Polycystic Kidney Disease

BACKGROUND AND OBJECTIVES

Disease-specific treatment options for autosomal dominant polycystic kidney disease are limited. Clinical intervention early in life is likely to have the greatest effect. In a 3-year randomized double-blind placebo-controlled phase 3 clinical trial, the authors recently showed that pravastatin decreased height-corrected total kidney volume (HtTKV) progression of structural kidney disease over a 3-year period. However, the underlying mechanisms have not been elucidated.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Participants were recruited nationally from July 2007 through October 2009. Plasma and urine samples collected at baseline, 18 months, and 36 months from 91 pediatric patients enrolled in the above-mentioned clinical trial were subjected to mass spectrometry-based biomarker analysis. Changes in biomarkers over 3 years were compared between placebo and pravastatin-treated groups. Linear regression was used to evaluate the changes in biomarkers with the percent change in HtTKV over 3 years.

RESULTS

Changes in plasma concentrations of proinflammatory and oxidative stress markers (9- hydroxyoctadecadienoic acid, 13-hydroxyoctadecadienoic acid, and 15-hydroxyeicosatetraenoic acid [HETE]) over 3 years were significantly different between the placebo and pravastatin-treated groups, with the pravastatin group showing a lower rate of biomarker increase. Urinary 8-HETE, 9-HETE, and 11-HETE were positively associated with the changes in HtTKV in the pravastatin group.

CONCLUSIONS

Pravastatin therapy diminished the increase of cyclooxygenase- and lipoxygenase-derived plasma lipid mediators. The identified biomarkers and related molecular pathways of inflammation and endothelial dysfunction may present potential targets for monitoring of disease severity and therapeutic intervention of autosomal dominant polycystic kidney disease.

Anti-inflammatory effect of simvastatin in hemodialysis patients

Background

Patients in the final stages of renal failure have accelerated inflammation conditions. Inflammation causes progressive kidney damage, faster progression of atherogenesis, chronic malnutrition and increased anemia, resulting in lower life expectancy of patients under dialysis. Statins have pleiotropic effects, because the drug has effects more than just decreasing lipids such as antioxidant effects, changes in endothelial dysfunction, stabilizing the plaque and immune system regulator.

Objectives

The aim of the study was to evaluate anti-inflammatory effect of simvastatin (one of the statins) in patients under hemodialysis.

Patients and Methods

In this clinical trial study, 40 patients under hemodialysis were studied for 12 weeks. Patients were divided into treatment (25 cases) and control groups (15 cases). The treatment group received a daily dosage of 20 mg of simvastatin, while the control group received no medication. The serum amounts of hs-CRP, IL6, Hb and WBC count were measured and compared at baseline and after 12 weeks. In addition, probable hepatic and muscular complications were studied in patients.

Results

At baseline, each of treatment and control groups had similar characteristics. During the study, the average level of CRP decreased in the treatment group (P = 0.04), while it was increased in the control group. The amount of serum IL-6 dropped in the treatment group (P = 0.01); however, it was increased in the control group. In both groups, the level of Hb increased significantly at the end of study in the treatment group (P = 0.007) and the control group (P = 0.016). The average WBC count decreased significantly in the treatment group and the control group (P = 0.003). There was no significant change in hepatic and muscular enzymes in the two groups.

Conclusions

End stage renal disease (ESRD) have accelerated inflammatory conditions. Simvastatin clearly lowers the serum levels of CRP and IL-6, and the white blood cell count in dialysis patients. Administering Simvastatin to dialysis patients is safe.

Atorvastatin treatment attenuates renal injury in an experimental model of ischemia-reperfusion in rats

BACKGROUND

Recent studies in animal models have shown that statins can protect against renal failure independent of their lipid-lowering actions, and there is also an association between statin use and improved renal function after suprarenal aortic clamping. We investigated the hypothesis that post-ischemic acute renal failure could be ameliorated with atorvastatin (ATO) treatment and the possible molecular mechanisms in a model of ischemia-reperfusion (IR) in rats.

METHODS

Twenty-four male Sprague-Dawley rats were divided into three groups: sham, IR, and IR + ATO. ATO was given by a single intraperitoneal injection (10 mg/kg) 30 min before reperfusion in the IR + ATO group. The IR group and sham group received saline vehicle via the intraperitoneal route.

RESULTS

After 24 h of IR, serum creatinine levels were increased in the IR group compared with the sham group (p < 0.001). ATO treatment reduced the elevation of serum creatinine level by 18% (p < 0.05) and significantly increased the creatinine clearance rate (p < 0.001). Concentrations of advanced oxidation protein products and malondialdehyde were reduced in the ATO group, approaching levels observed in sham-group rats. ATO treatment alleviated pathological changes in renal tubular cells. Protein and mRNA levels of intercellular adhesion molecule-1 and monocyte chemotactic protein-1 were reduced significantly.

CONCLUSIONS

These data suggest that direct protection of injured kidneys by ATO was possible even though the drug was injected 30 min before reperfusion, and that ATO may reduce IR injury by anti-inflammatory effects and by reducing oxidation stress.

Accelerated decline in renal function after acute myocardial infarction in patients with high low-density lipoprotein-cholesterol to high-density lipoprotein-cholesterol ratio

High low-density lipoprotein-cholesterol to high-density lipoprotein-cholesterol (L/H) ratio is associated with progressions of coronary arteriosclerosis and chronic kidney disease. On the other hand, renal function markedly declined after acute myocardial infarction (AMI). The aims of the present study were (1) to identify what type of patients with AMI would have high L/H ratio at follow-up and (2) to evaluate whether decline in renal function after AMI had accelerated or not in patients with high L/H ratio. The 190 eligible AMI patients who underwent primary percutaneous coronary intervention (PCI) and received atorvastatin (10 mg) were divided into one of two groups according to the L/H ratio at 6-month follow-up: L/H >2 group (n = 81) or L/H ≤2 group (n = 109). The characteristics on admission in the two groups were examined. Furthermore, changes in serum creatinine (sCr) and estimated glomerular filtration rate (eGFR) during 1- and 6-month follow-up were compared between the two groups. L/H >2 group were significantly younger and had greater body mass index (BMI) and worse lipid profile on admission compared with L/H ≤2 group. Percentage increase in sCr and percentage decrease in eGFR during 1-month follow-up in L/H >2 group tended to be greater than in L/H ≤2 group, and those during 6-month follow-up were significantly greater (16.5 ± 2.77 vs. 9.79 ± 2.23 %, p = 0.03 and 11.8 ± 1.93 vs. 2.75 ± 3.85 %, p = 0.04, respectively). In AMI patients undergoing primary PCI, those who were young and had large BMI and poor lipid profile on admission were likely to have a high L/H ratio at follow-up despite statin therapy. In addition, the decline in renal function after AMI had significantly accelerated in patients with high L/H ratio.

The Nrf2 system as a potential target for the development of indirect antioxidants

Oxidative stress causes damage to multiple cellular components such as DNA, proteins, and lipids, and is implicated in various human diseases including cancer, neurodegeneration, inflammatory diseases, and aging. In response to oxidative attack, cells have developed an antioxidant defense system to maintain cellular redox homeostasis and to protect cells from damage. The thiol-containing small molecules (e.g. glutathione), reactive oxygen species-inactivating enzymes (e.g. glutathione peroxidase), and phase 2 detoxifying enzymes (e.g. NAD(P)H: quinine oxidoreductase 1 and glutathione-S-transferases) are members of this antioxidant system. NF-E2-related factor 2 (Nrf2) is a CNC-bZIP transcription factor which regulates the basal and inducible expression of a wide array of antioxidant genes. Following dissociation from the cytosolic protein Keap1, a scaffolding protein which binds Nrf2 and Cul3 ubiquitin ligase for proteasome degradation, Nrf2 rapidly accumulates in the nucleus and transactivates the antioxidant response element in the promoter region of many antioxidant genes. The critical role of Nrf2 has been demonstrated by various animal studies showing that mice with a targeted disruption of the nrf2 gene are prone to develop lesions in response to environmental toxicants/carcinogens, drugs, and inflammatory insults. In this review, we discuss the role of the Nrf2 system, with particular focus on Nrf2-controlled target genes and the potential pleiotropic effects of Nrf2 activation of indirect antioxidants.

Efficacy and safety of Monascus purpureus Went rice in children and young adults with secondary hyperlipidemia: a preliminary report

BACKGROUNDS/AIMS

Nephrotic dyslipidemia is a risk factor for development of systemic atherosclerosis; also it may aggravate glomerulosclerosis and enhance progression of glomerular disease. We aimed to assess the efficacy and safety of Monascus purpureus Went rice vs. fluvastatin therapy in the management of nephrotic dyslipidemia.

METHODS

Seventy-two patients with idiopathic persistent nephrotic syndrome with secondary dyslipidemia were included. They were randomly allocated into 3 - age and sex - matched groups. The first group comprised of 20 cases and were given Monascus purpureus Went rice, second group comprised 30 cases were given fluvastatin. The remaining 22 received no anti-dyslipidemic therapy and constituted a control group. All of these patients were subjected to thorough laboratory investigations including renal function tests, lipogram and neurological assessment.

RESULTS

Our results showed that both fluvastatin and Monascus purpureus Went rice were well-tolerated with no significant side effects. Both of them significantly reduced cholesterol after 6 months and 1 year. In comparison to baseline values, fluvastatin achieved a significant and progressive reduction of serum cholesterol by 35%, 38% and 42% at 3 months, 6 months and after 1 year respectively (p<0.001). Similar reductions were observed in the Monascus purpureus Went rice group. After one year we observed that serum cholesterol was significantly lower in statin and Monascus purpureus Went rice groups compared to the control group.

CONCLUSION

Monascus purpureus Went rice is safe, effective cholesterol lowering agent for nephrotic dyslipidemia both in adults and children.

Cystatin C and carotid intima-media thickness in asymptomatic adults: the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

Persons with early kidney disease have an increased risk of cardiovascular events and mortality, but the importance of accelerated atherosclerosis in promoting these outcomes is unclear. We therefore explored whether serum cystatin C level is associated with carotid intima-media thickness (IMT) in ambulatory adults without clinical heart disease.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

We evaluated 6,557 ethnically diverse persons free of clinical cardiovascular disease aged 45 to 84 years at the baseline visit of the Multi-Ethnic Study of Atherosclerosis.

PREDICTORS

Kidney function was estimated by using 2 methods: serum cystatin C level and estimated glomerular filtration rate, based on creatinine and cystatin C levels.

OUTCOMES & MEASUREMENTS

Study outcomes were internal and common carotid IMT, measured by using high-resolution B-mode ultrasound. Multivariate linear and logistic regressions were used to evaluate the independent association of kidney function with carotid IMT.

RESULTS

In unadjusted linear analysis, each SD (0.23 mg/L) greater cystatin C level was associated with 0.091-mm greater internal carotid IMT (P < 0.001), but this association was diminished by 70% after adjustment for age, sex, and race/ethnicity (0.027 mm; P < 0.001) and was no longer significant after adjustment for cardiovascular risk factors (0.005 mm; P = 0.5). Similarly, the strong unadjusted associations of cystatin C level with common carotid IMT disappeared after adjustment. Chronic kidney disease, defined by using either creatinine level or cystatin C-based estimated glomerular filtration rate less than 60 mL/min/1.73 m(2), had no independent association with internal and common carotid IMT.

LIMITATIONS

There were few participants with severe kidney disease.

CONCLUSIONS

Cystatin C level had no independent association with carotid IMT in a population free of clinical heart disease. This observation suggests that accelerated atherosclerosis is unlikely to be the primary mechanism explaining the independent association of cystatin C level with cardiovascular risk.

Pharmacological modulation of epithelial mesenchymal transition caused by angiotensin II. Role of ROCK and MAPK pathways

PURPOSE

Tubulointerstitial fibrosis is a final common pathway to end-stage chronic kidney diseases, which are characterized by elevated renal angiotensin II (AngII) production. This peptide participates in kidney damage inducing fibrosis and epithelial mesenchymal transition (EMT). Our aim was to describe potential therapeutic targets in AngII-induced EMT, investigating the blockade of different intracellular pathways.

METHODS

Studies were done in human tubular epithelial cells (HK2 cell line), evaluating changes in phenotype and EMT markers (Western blot and immunofluorescence).

RESULTS

Treatment of HK2 cells with AngII for 3 days caused transdifferentiation into myofibroblast-like cells. The blockade of MAPKs cascade, using specific inhibitors of p38 (SB203580), extracellular signal-regulated kinase1/2 (ERK; PD98059) and Jun N-terminal kinase (JNK) (SP600125), diminished AngII-induced EMT. The blockade of RhoA/ROCK pathway, by transfection of a RhoA dominant-negative vector or by ROCK inhibition with Y-27632 or fasudil, inhibited EMT caused by AngII. Connective tissue growth factor (CTGF) is a downstream mediator of AngII-induced EMT. MAPKs and ROCK inhibitors blocked CTGF overexpression induced by AngII. HMG-CoA reductase inhibitors, although blocked AngII-mediated kinases activation, only partially diminished EMT and did not regulate CTGF.

CONCLUSIONS

These data suggest a potential therapeutic use of kinase inhibitors in renal fibrosis.

Polyisoprenoid alcohols--recent results of structural studies

Polyisoprenoid alcohols (polyprenols and dolichols) are linear polymers of from several up to more than 100 isoprene units identified in almost all living organisms. Studies of their chemical structures have resulted in the discovery of new variants such as the recently described alloprenols with reversed configuration of the double bond in the alpha-isoprene unit. In parallel, structural elucidation of metabolically labeled plant dolichols has indicated that both the mevalonate and methylerythritol phosphate pathways are involved in the biosynthesis of dolichols in roots, leading to the construction of a spatial model of their biosynthesis. According to this model, in root cells, synthesis of the dolichol molecule is initiated in the plastids, and the resulting intermediates, oligoprenyl diphosphates, are exported to the cytoplasm and are elongated up to the desired chain length. The metabolic consequences of this putative model are discussed in the context of the enzymatic machinery involved.