The combination of lovastatin and enalapril in a model of progressive renal disease

Effects of Atorvastatin Dose and Concomitant Use of Angiotensin-Converting Enzyme Inhibitors on Renal Function Changes over Time in Patients with Stable Coronary Artery Disease: A Prospective Observational Study

Angiotensin-converting enzyme inhibitors (ACEI) and statins are widely used in patients with coronary artery disease (CAD). Our aim was to compare changes in glomerular filtration rate (GFR) over time in subjects with stable CAD according to atorvastatin dose and concomitant use of ACEI. We studied 78 men with stable CAD referred for an elective coronary angiography who attained the then-current guideline-recommended target level of low-density lipoproteins (LDL) cholesterol below 2.5 mmol/L in a routine fasting lipid panel on admission and were receiving atorvastatin at a daily dose of 10-40 mg for ≥3 months preceding the index hospitalization. Due to an observational study design, atorvastatin dosage was not intentionally modified for other reasons. GFR was estimated during index hospitalization and at about one year after discharge from our center. Irrespective of ACEI use, a prevention of kidney function loss was observed only in those treated with the highest atorvastatin dose. In 38 subjects on ACEI, both of the higher atorvastatin doses were associated with increasing beneficial effects on GFR changes (mean ± SEM: -4.2 ± 2.4, 1.1 ± 1.6, 5.2 ± 2.4 mL/min per 1.73 m² for the 10-mg, 20-mg and 40-mg atorvastatin group, respectively, p = 0.02 by ANOVA; Spearman's rho = 0.50, p = 0.001 for trend). In sharp contrast, in 40 patients without ACEI, no significant trend effect was observed across increasing atorvastatin dosage (respective GFR changes: -1.3 ± 1.0, -4.7 ± 2.1, 4.8 ± 3.6 mL/min per 1.73 m², p = 0.02 by ANOVA; rho = 0.08, p = 0.6 for trend). The results were substantially unchanged after adjustment for baseline GFR or time-dependent variations of LDL cholesterol. Thus, concomitant ACEI use appears to facilitate the ability of increasing atorvastatin doses to beneficially modulate time-dependent changes in GFR in men with stable CAD.

Most appropriate animal models to study the efficacy of statins: a systematic review

BACKGROUND

In animal models and clinical trials, statins are reported as effective in reducing cholesterol levels and lowering the risk of cardiovascular diseases. We have aggregated the findings in animal models - mice, rats and rabbits - using the technique of systematic review and meta-analysis to highlight differences in the efficacy of statins.

MATERIALS AND METHODS

We searched Medline and Embase. After examining all eligible articles, we extracted results about total cholesterol and other blood parameters, blood pressure, myocardial infarction and survival. Weighted and standard mean difference random effects meta-analysis was used to measure overall efficacy in prespecified species, strains and subgroups.

RESULTS

We included in systematic review 161 animal studies and we analysed 120 studies, accounting for 2432 animals. Statins lowered the total cholesterol across all species, although with large differences in the effect size: -30% in rabbits, -20% in mice and -10% in rats. The reduction was larger in animals fed on a high-cholesterol diet. Statins reduced infarct volume but did not consistently reduce the blood pressure or effect the overall survival. Few studies considered strains at high risk of cardiovascular diseases or hard outcomes.

CONCLUSIONS

Although statins showed substantial efficacy in animal models, few preclinical data considered conditions mimicking human pathologies for which the drugs are clinically indicated and utilized. The empirical finding that statins are more effective in lowering cholesterol derived from an external source (i.e. diet) conflicts with statin's supposed primary mechanism of action.

Does remission of renal disease associated with antihypertensive treatment exist?

In diabetic and nondiabetic chronic nephropathies, high blood pressure and urinary loss of proteins represent major determinants of progressive renal function decline. Reducing blood pressure with drugs that inhibit the renin-angiotensin system also lowers glomerular hypertension and ameliorates glomerular sieving properties, thus reducing proteinuria. Reducing urinary protein levels with angiotensin-converting enzyme inhibitors (ACEi) or angiotensin II receptor antagonists (ARA) limits renal function decline to the point that remission of disease and regression of renal lesions have been observed in experimental animals and in humans. This therapy, however, may not be effective in all patients. For patients who do not achieve complete remission of proteinuria, renoprotective treatment should include intensified blood pressure control (and metabolic control in diabetes) and amelioration of dyslipidemia. Early intervention, before progressive glomerulosclerosis and scarring is initiated by increased protein traffic, may be important to maximize reno- and cardioprotection, especially in diabetes.

Effect of short-term rosuvastatin treatment on estimated glomerular filtration rate

To define the effect of short-term rosuvastatin treatment on the estimated glomerular filtration rate (eGFR), the database of controlled clinical trials in the Rosuvastatin Clinical Development Program was reviewed. Thirteen studies comprising 3,956 rosuvastatin-treated patients were selected based on a serum creatinine measurement at 6 or 8 weeks after initiation of rosuvastatin treatment, randomization to approved and marketed rosuvastatin doses (5 to 40 mg), and unchanged rosuvastatin dose from treatment initiation (baseline) through 6 to 8 weeks of treatment. eGFR was determined with the Modification of Diet in Renal Disease formula. eGFR significantly increased for each dose of rosuvastatin individually and for all doses combined compared with baseline (range +0.9 to +3.2 ml/min/1.73 m2). Further analysis of 5 blinded, placebo-controlled trials comprising 525 patients showed an increase in eGFR of +0.8 ml/min/1.73 m2 (95% confidence interval +0.1 to +1.5) for all rosuvastatin-treated patients, which was significantly different from baseline (p <0.04) and from a change of -1.5 ml/min/1.73 m2 in the placebo-treated patients (95% confidence interval -2.5 to -0.5, p <0.001). The increase in eGFR for rosuvastatin-treated patients was consistent across all major demographic and clinical subgroups of interest, including patients with baseline proteinuria, baseline eGFR <60 ml/min/1.73 m2, and in patients with hypertension and/or diabetes. In conclusion, these results are consistent with previous rosuvastatin studies that showed an upward trend in eGFR with long-term treatment (> or =96 weeks) and with the hypothesis that statins may have pleiotropic mechanisms of action that include beneficial renal effects.

Enhanced acetylcholine-induced dilation in afferent arterioles in simvastatin-fed rats

OBJECTIVE

3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors have been shown to increase renal blood flow and glomerular filtration rate independent of their lipid lowering effects. The purpose of this study was to determine the effect of simvastatin on acetylcholine-induced vasodilation in the renal microcirculation. The hypothesis of the study was that simvastatin would increase acetylcholine-induced vasodilation in the renal microcirculation.

METHODS

The hydronephrotic kidney preparation was used. On the day of the experiment the kidney was prepared for videomicroscopy and dose-response curves were done with acetylcholine and sodium nitroprusside (10(-10) M to 10(-5) M) in simvastatin-fed rats ??(n=8) and control rats (n=13). The vasodilator responses of afferent and efferent arterioles were directly quantitated using videomicroscopy. L-NAME; (N(omega)-nitro-L-arginine methyl ester) was also given in a group of simvastatin-fed rats (10(-5) M) to determine if it would block the acetylcholine (Ach)-induced vasodilation.

RESULTS

Simvastatin enhanced Ach-induced vasodilation in the afferent arteriole compared to control rat responses to Ach. At 10(-7) M, ACH caused a 31.6+/-7.2% increase from baseline diameter in the afferent arteriole in the simvastatin-fed rats compared to a 23+/-8.1% vasodilation in the control rats (p<0.05). There were no differences in the response to ACH in the efferent arteriole between the two groups. L-NAME completely abolished the ACH response in the simvastatin-fed rats.

CONCLUSIONS

The increase in renal blood flow and glomerular filtration rate observed with simvastatin may be due to its preglomerular vasodilator effects. This may be due to an increase in nitric oxide production.

Statins and proteinuria

The proteinuria associated with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors is composed of primarily low-molecular weight proteins that disappear rapidly following discontinuation of the statin agent. More importantly, no evidence exists of nephrotoxicity or reduced renal function observed with the approved clinical dosages of any available statins. Recent clinical studies have suggested actual improvement in renal function demonstrated by decreases in creatinine concentrations and improvement in estimated glomerular filtration rates with both short-term and long-term administration of these agents. The progressive fibrosis and renal scarring of chronic kidney disease appears to be the end result of increased protein traffic in the proximal renal tubule. Early animal and recent clinical studies have suggested that treatment with statin agents in established chronic kidney disease can, in fact, provide renoprotection over and above that observed with aggressive blood pressure control and the use of angiotensin II antagonists.

Combined Effects of Losartan and Pravastatin on Interstitial Inflammation and Fibrosis in Chronic Cyclosporine-Induced Nephropathy

BACKGROUND

Statins and angiotensin II type I receptor blockers have synergistic effects on vascular smooth-muscle-cell proliferation and the progression of renal diseases. We evaluated whether combined treatment with losartan (LSRT) and pravastatin (PRVT) affords superior protection compared with their respective monotherapies in treating chronic cyclosporine (CsA)-induced nephropathy in rats.

METHODS

Rats maintained on a low salt diet were given vehicle, CsA (15 mg/kg), CsA and LSRT (10 mg/kg), CsA and PRVT (5 mg/kg), or a combination of CsA, LSRT, and PRVT for 28 days. Basic parameters (renal function, systolic blood pressure, serum high-sensitivity C-reactive protein [hs-CRP], and lipid profiles), histopathology (arteriolopathy, tubulointerstitial fibrosis, and inflammatory cell infiltration), and inflammatory and fibrotic factors (intrarenal CRP, angiotensin II, osteopontin, and transforming growth factor [TGF]-beta1) were studied.

RESULTS

LSRT or PRVT treatment significantly attenuated the histopathologic changes induced by CsA, and combined treatment with LSRT and PRVT further decreased these parameters compared with giving each drug alone. Increased levels of angiotensin II, intrarenal CRP, osteopontin, and TGF-beta1 in CsA-treated rat kidney were reduced by treatment with either LSRT or PRVT and were further decreased by the combination of the two drugs. There were no significant differences in systolic blood pressure or serum lipid parameters between groups.

CONCLUSIONS

Combined treatment with LSRT and PRVT provided synergistic effects in attenuating inflammatory and fibrotic processes in a rat model of chronic CsA-induced nephropathy, and this effect was independent of their hypolipidemic and hypotensive actions.

Hyperlipidemic profiles during remission in childhood idiopathic nephrotic syndrome

Hyperlipidemia, an important characteristic of idiopathic nephrotic syndrome in children (NS), is usually observed during the active phase of the disease and disappears with the resolution of the proteinuria. However, persisting lipid anomalies during remission have been reported in a few studies and raise the question of the later development of atherosclerosis. Plasma lipid profiles in 25 children with NS at remission, with or without active prednisone treatment, were compared with those of an age-matched population. The results indicate that plasma total and LDL-cholesterol levels were above the 95(th) percentile for age and sex in 12 of the 25 patients (48%) with 7 of them having apolipoprotein B and triglyceride concentrations above the 95(th) percentile. Moreover, frequently relapsing children were more likely to have abnormal lipid profile during the remission. We conclude that close monitoring of lipid levels during the remission of the NS especially in those with frequent relapses, is necessary to select the high-risk patients.

Simvastatin Attenuates Renal Ischemia/Reperfusion Injury in Rats Administered Cyclosporine A

BACKGROUND

3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors increase renal blood flow independent of their lipid-lowering properties. In organ transplantation, the calcineurin inhibitor cyclosporine A (CyA) is the immunosuppressant of choice. However, its renal vasoconstrictor properties limit its use. This study aimed to determine the effect of an HMG-CoA reductase inhibitor, simvastatin (Zocor), on renal function in rats after ischemia/reperfusion injury (I/R) with concomitant CyA treatment.

METHODS

Male Wistar rats (250 g) were anesthetized and the suprarenal aorta clamped for 40 minutes. The right kidney was removed. After recovery, the rats were divided into 5 groups: (1) control rats, no ischemia, no treatment; (2) ischemia with no treatment; (3) ischemia plus CyA only; (4) ischemia plus CyA and low-dose simvastatin; and (5) ischemia plus CyA and high-dose simvastatin. Five to 7 days after I/R injury, glomerular filtration rate (GFR) was determined using urinary iohexol clearance.

RESULTS

The GFR values (mL/min) for all 5 groups were as follows: (1) 1.23 +/- 0.08; (2) 1.05 +/- 0.10; (3) 0.44 +/- 0.06 (P < 0.05 versus groups 1, 2, and 5; one-way analysis of variance); (4) 0.51 +/- 0.04 (P < 0.05 versus groups 1, 2, and 5; one-way analysis of variance); and (5) 0.85 +/- 0.11.

CONCLUSIONS

After I/R injury and cyclosporine treatment, simvastatin preserved renal function compared with cyclosporine treatment alone because it may not have a direct vasoconstrictor effect on the renal microcirculation. In fact, it may exhibit vasodilator properties on the renal microcirculation mediated by nitric oxide.

Effect of combining ACE inhibitor and statin in severe experimental nephropathy

BACKGROUND

Angiotensin-converting enzyme (ACE) inhibitor therapy given soon after disease induction uniformly prevents proteinuria in virtually all models of disease progression. This does not necessarily apply to patients with proteinuric nephropathies, who might be referred late in the course of their disease. Here we used a severe rat model of passive Heymann nephritis (PHN), which may mimic advanced phases of human membranous nephropathy, to study the response to ACE inhibitor alone or in combination with a HMG CoA reductase inhibitor (statin) that independently of the cholesterol-lowering effect influences pathways involved in inflammatory and fibrogenic processes. Therapies started when animals had massive proteinuria and renal lesions.

METHODS

PHN was accelerated by uninephrectomy seven days after IV injection of rabbit anti-FX1A antibody. Four months later, when massive proteinuria and renal lesions were present, the rats were divided into five groups and daily given orally: vehicle; lisinopril 40 mg/L; lisinopril 400 mg/L; simvastatin 2 mg/kg b.i.d; or lisinopril 40 mg/L plus simvastatin. Six normal rats served as controls. Animals were sacrificed at 10 months.

RESULTS

By the end of the study three PHN rats died in the vehicle group, four in the group given lisinopril at 40 mg/L and two in the group at 400 mg/L, whereas all rats on simvastatin or combined therapy were alive. Blood pressure increased during time in PHN and was normalized by treatment with ACE inhibitor and combined therapy. Even at the high dose lisinopril failed to reduce proteinuria. Simvastatin only partially affected proteinuria. However, combining lisinopril with simvastatin had a remarkable antiproteinuric effect, such that at 10 months the urinary proteins were comparable to pre-treatment values and significantly lower than either the vehicle or lisinopril groups. Hypercholesterolemia of PHN rats was limited by combined therapy, and a positive correlation was found between serum cholesterol and proteinuria. Renal function was only partially ameliorated by simvastatin but significantly improved by combined therapy. Drug combination significantly limited glomerulosclerosis, tubular damage and interstitial inflammation, compared to vehicle or drugs alone. Up-regulation of monocyte chemoattractant protein-1 (MCP-1) mRNA in PHN kidneys was not affected by lisinopril, it was inhibited by 30% after simvastatin, and almost completely normalized by lisinopril plus simvastatin.

CONCLUSIONS

These data suggest that a combined ACE inhibitor and statin approach could represent a therapeutic option for patients with advanced renal disease in whom ACE inhibitors alone fail to lower proteinuria and injury to any substantial extent.

Lovastatin preserves renal function in experimental diabetes

Although hyperlipidemia has been associated with the progression of glomerulosclerosis, little attention has been directed toward the use of lipid-lowering agents in altering diabetic nephropathy. We tested the hypothesis that lovastatin and the combination of lovastatin and enalapril would preserve renal function in streptozotocin-induced diabetic Wistar rats. Five groups of animals were studied: group 1, nondiabetic (n = 10); group 2, diabetic, insulin only (n = 12); group 3, lovastatin, (15 mg/kg/day, n = 13); group 4, enalapril, (50 mg/L drinking water, n = 10) and group 5, lovastatin plus enalapril, (n = 14). After 8 weeks of treatment, glomerular filtration rate (GFR, insulin clearance) was measured in anesthetized animals. The diabetic group was characterized by a GFR of 0.18 +/- 0.03 ml/min/g of kidney weight (gKW), a blood glucose level of 441 +/- 36 mg/dL, plasma cholesterol and triglyceride levels of 64 +/- 6.0 and 103 +/- 26.0 mg/dL. Lovastatin preserved GFR, 0.52 +/- 0.06 ml/min/gKW compared with the diabetic control subjects (P < 0.05). Enalapril also maintained GFR (0.42 +/- 0.06 ml/min/gKW, P < 0.05). In the lovastatin plus enalapril group, GFR (0.62 +/- 0.05 ml/min/gKW) was greater than in the enalapril group (P < 0.05), but was not different from the lovastatin group. Plasma lipid levels were not altered in any of the groups. Assessment of the kidneys by histology after treatment showed that the mesangial matrix injury score was better in the lovastatin, enalapril, and lovastatin plus enalapril groups compared with the diabetic group (P < 0.05). Lovastatin, enalapril, and lovastatin plus enalapril abrogated the decline in GFR and glomerular injury in diabetic rats. Lovastatin's direct renal protective effect seems to be independent of its lipid-lowering properties.

Renal microcirculatory effects of lovastatin in a rat model of reduced renal mass

OBJECTIVES

Patients with reduced renal mass are at increased risk of developing renal failure. A remnant kidney model has been used to study the hemodynamic and structural changes that occur. We recently reported that the lipid-lowering agent lovastatin preserves renal function in this model. The purpose of the present study was to determine the specific effects of lovastation on the renal microcirculation of rats with reduced renal mass.

METHODS

We used the rat hydronephrotic kidney preparation with a 5/6 partial nephrectomy. This model allows direct visualization of preglomerular and postglomerular vessels using videomicroscopy. The diameters and vascular responses to acetylcholine and angiotensin II of the interlobular, afferent, and efferent vessels were determined in two groups of animals with renal mass reduction: 15 rats with no lovastatin treatment and 18 rats treated with oral lovastatin (15 mg/kg body weight/day) for 2 weeks.

RESULTS

In the lovastatin-treated rats, the baseline efferent vessel diameter was smaller by 21% (P < 0.05), but the interlobular and afferent vessel baseline diameters were not different from those in the untreated rats. Serum creatinine levels were lower in the treated rats (1.5 +/- 0.1 versus 2.0 +/- 0.2 mg/dL, P < 0.05), but serum lipids were not different. In the lovastatin-treated rats, vascular reactivity to acetylcholine was enhanced in the afferent and decreased in the efferent vessels.

CONCLUSIONS

In this renal ablation model, lovastatin preserved renal function as measured by serum creatinine without lowering plasma lipid levels. Lovastatin treatment resulted in smaller efferent vessel diameters. Lovastatin also increased the vasodilatory response to acetylcholine in the afferent vessels. Together, these preglomerular and postglomerular changes would increase the single-nephron glomerular filtration rate. The renal protective effect of lovastatin may be due to these vasoactive effects on the renal microcirculation.

Renal hemodynamic effects of lovastatin in a renal ablation model

OBJECTIVES

Patients with renal mass reduction of more than 50% are at increased risk for progressive renal failure. Lipid-lowering agents have been shown to preserve renal function in various models of chronic renal failure. This study was performed to evaluate the hemodynamic effects of lovastatin, a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, in the remnant kidney model.

METHODS

Two groups of animals were studied. Group 1 (n = 9) served as controls and group 2 (n = 14) received lovastatin, 15 mg/kg/day orally, for 2 weeks after renal ablation. Glomerular filtration rate (GFR, inulin clearance), renal blood flow (RBF, ultrasonic flow probe), and 24-hour protein excretion were measured in anesthetized rats.

RESULTS

Two weeks after renal ablation, GFR was 0.28 +/- 0.09 mL/min/gkw (gram kidney weight) in group 1, whereas in group 2, lovastatin preserved GFR at 0.58 +/- 0.3 mL/min/gkw (P < 0.05). RBF in group 1 was 1.2 +/- 0.2 mL/min/gkw and increased to 2.1 +/- 0.4 mL/min/gkw in group 2 (P < 0.05), representing a 43% increase. Protein excretion decreased significantly to 13 +/- 1.7 mg/24 hr in group 2. The lovastatin-treated group had a lower serum cholesterol (59 +/- 3 mg/dL versus 71 +/- 2 mg/dL, P < 0.05), but serum triglyceride levels were not different between the two groups.

CONCLUSIONS

Lovastatin preserves renal function in a renal ablation model after 2 weeks of treatment. It specifically increased total RBF. Therefore, in addition to its known cholesterol lowering effect, lovastatin also has the direct renal hemodynamic effect of increasing RBF and maintaining GFR.

Long-term therapy with enalapril in patients with nephrotic-range proteinuria

The effect of enalapril on urinary protein excretion and renal function was studied in six paediatric patients with various renal diseases causing nephroticrange proteinuria. In three younger children (aged 7-9 years) with steroid-resistant nephrotic syndrome, enalapril at a dose of 0.5 mg/kg per day given for 24 months yielded a temporary reduction of proteinuria in one child, a moderate and steady decrease in another and a complete disappearance of proteinuria in the third. Three adolescents, aged 17 years, took enalapril for 24 months at a dose of 20 mg/day. We observed no effect on proteiuria in one patient with Alport syndrome, a complete disappearance of urinary protein in one patient with membranoproliferative glomerulonephritis and a moderate decrease in the third patient who had idiopathic steroid-resistant nephrotic syndrome. Enalapril therapy resulted in an important reduction of proteinuria in two patients and a moderate decrease in three others. However this therapy was accompanied by a fall in glomerular filtration in all subjects, which was very marked in two patients. This fall in glomerular filtration may, however, simply reflect the natural course of the disease.