Effect of chronic cholesterol loading in the development of acute ischemic renal failure in rats

Statins and renovascular disease in the elderly: a population-based cohort study

AIMS

More than 90% of cases of renovascular disease (RVD) are caused by atherosclerosis; thus patients with this condition are at high risk for vascular events. We examined the association of statins with prognosis in patients with RVD.

METHODS AND RESULTS

We performed a population-based cohort study in 4040 patients with RVD older than 65 years using province-wide health data in Ontario, Canada. The primary outcome was time to first cardiorenal event, specifically myocardial infarction, stroke, heart failure, acute renal failure, dialysis or death; the primary analysis used a time-dependent covariate for statin exposure. Despite having a greater burden of cardiovascular and renal comorbidity, the risk of the primary outcome was significantly lower in statin users than in non-users [unadjusted hazard ratio (HR) 0.51, 95% confidence interval (CI) 0.47-0.57; P < 0.0001]. This association was materially unchanged after adjusting for demographic characteristics, cardiovascular risk factors, other comorbidities, measures of health-care utilization, screening, and concomitant medications (adjusted HR 0.51, 95% CI 0.46-0.57). An analysis using the same endpoint in a propensity-matched cohort without time-dependent statin exposure revealed a lower risk of the primary outcome in statin-treated patients but with a substantially more conservative point estimate (HR 0.82, 95% CI 0.71-0.95).

CONCLUSION

These data suggest that statins are associated with improved prognosis in elderly patients with RVD.

Recent advances in statins and the kidney

BACKGROUND

Experimental and clinical studies have suggested a correlation between the progression of renal disease and dyslipidemia. Indeed, apolipoprotein B-containing lipoproteins have been demonstrated to be an independent risk factor for the progression of renal disease in humans. Interventional strategies in experimental models of renal disease have clearly demonstrated a beneficial effect on renal structure and function in a variety of models of renal disease. Investigations into the mechanisms whereby reduction of lipids by lipid-lowering agents benefits renal disease have suggested that the 3-hydroxy-3-methylglutaryl coenzyme reductase inhibitors, the so-called statin class of lipid-lowering agents, may have additional effects on the biology of inflammation that are germane to the progression of renal disease.

METHODS

Both in vivo and in vitro studies that investigated secondary mechanisms of statin effects are reviewed. In addition, new studies that investigated the effects on novel cellular mechanisms are presented.

RESULTS

Lipid-lowering agents appear to have biologically important effects in modulating a variety of intracellular signaling systems involved in cell proliferation, inflammatory responses that involve macrophage adhesion, recruitment, and maturation. In addition, the effects on fibrogenesis have been recently defined. These latter effects may influence not only the development of glomerulosclerosis, but also interstitial fibrosis. These potentially major effects of lipid-lowering agents appear to be related to the effects on intracellular synthesis of nonsterol isoprenoids, which are involved in prenylation of critical small molecular weight proteins involved in cell signal transduction.

CONCLUSIONS

In addition to the beneficial effects of the reduction in serum lipids, statins and other lipid-lowering agents may influence important intracellular pathways that are involved in the inflammatory and fibrogenic responses, which are common components of many forms of progressive renal injury.

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.