The influence of short-term treatment with simvastatin on the inflammatory profile of patients with hypercholesterolaemia

The relationship of oxidative stress and cholesterol with dipping status before and after aerobic exercise training

OBJECTIVE

The purpose of this study was to examine the effects of aerobic exercise training (AEXT) on dipping status in pre-hypertensive and stage-1 hypertensive individuals. A secondary purpose was to evaluate whether AEXT alters oxidative stress and endothelial biomarkers correlated to dipping status.

METHODS

Twenty-three subjects underwent 24-h ambulatory blood pressure monitoring at baseline and after 6 months of AEXT. AEXT consisted of training at 70% VO(2max) 3 days/week for 6 months. Total cholesterol, high-density lipoprotein-cholesterol, low-density lipoprotein (LDL)-cholesterol, oxidized LDL (ox-LDL), triglycerides, urinary and plasma nitric oxide end-products, superoxide dismutase and 8-iso-PGF(2alpha) were measured before and after AEXT. Statistically, ANOVA and linear regression were used.

RESULTS

Before and after AEXT, there were no significant differences between dippers and non-dippers in any of the biomarkers except for total cholesterol following AEXT. In a sub-analysis following AEXT, 14 subjects retained their original dipping status, five subjects changed from dippers to non-dippers and four subjects changed from non-dippers to dippers. Significant differences existed between these groups in changes in total and LDL-cholesterol, ox-LDL, 8-iso-PGF(2alpha) and % Dip.

CONCLUSIONS

Changes in cholesterol levels but not oxidative stress or endothelial biomarkers were related to changes in BP variables following AEXT in dippers and non-dippers.

Effects of simvastatin on plasma antioxidant status and vitamins in hypercholesterolemic patients

BACKGROUND

Statins are known to possess antioxidant properties in addition to their cholesterol-lowering effects. However, recent studies have suggested that statins reduce the levels of antioxidant vitamins such as vitamin E and coenzyme Q(10), possibly resulting in impaired left ventricular function. We investigated the effects of simvastatin on the blood lipids, LDL oxidation and plasma antioxidant status, and whether these effects were associated with changes in plasma antioxidant vitamin levels.

METHODS

Simvastatin (20-40 mg/day) was administered for 8 weeks in seventy-six hypercholesterolemic patients. We measured plasma lipids, oxidized LDL, total radical trapping antioxidant potential (TRAP) and plasma antioxidant vitamin levels at baseline and after 8 weeks of simvastatin administration.

RESULTS

Simvastatin significantly lowered serum levels of total cholesterol and LDL-cholesterol by 30.1% and 41.9%, respectively. A significant reduction in oxidized LDL levels (p<0.0001) and improvement in plasma antioxidant status as measured by TRAP (p<0.05) after the 8-week simvastatin treatment were observed. Regarding the effects of simvastatin on plasma antioxidant vitamin levels, there were significant increases in the levels of lipid-corrected retinol (p<0.001), alpha-tocopherol (p<0.001) and gamma-tocopherol (p<0.005) after the 8-week simvastatin treatment. Lipid-corrected levels of coenzyme Q10 and carotenoids remained unchanged after simvastatin treatment.

CONCLUSIONS

Our results show that simvastatin reduced blood lipids and circulating oxidized LDL, and improved plasma antioxidant status without altering the antioxidant vitamin system. These data indicate that simvastatin not only decreases blood lipids and circulating oxidized LDL but also increases lipid corrected levels of antioxidant vitamins and may improve plasma antioxidant status synergizing with the biological effects of antioxidants.

Reduction of serum C-reactive protein by statin therapy may reflect decreased isoprenylation of Rac-1, a mediator of the IL-6 signal transduction pathway

Recent studies demonstrate that statin therapy decreases plasma levels of C-reactive protein (CRP), a potent risk factor for thrombotic vascular events. CRP is an acute phase reactant, and most circulating CRP is synthesized by hepatocytes in response to IL-6. Since statins do not appear to have a consistent impact on serum levels of IL-6, their impact on plasma CRP very likely reflects down-regulation of hepatocyte responsiveness to this cytokine. The ability of IL-6 to promote transcription of CRP is mediated, in large part, by activation of the transcription factor STAT3; this activation requires both a tyrosine phosphorylation (mediated by the IL-6 receptor complex) and a serine phosphorylation (Ser-727), the origin of which has been more obscure. There is new evidence that, when hepatocytes are exposed to IL-6, the consequent serine phosphorylation of STATS is mediated by a signal transduction pathway in which the G-protein Rac-1 plays an obligate role. Inasmuch as the proper function of Rac-1 is contingent on isoprenylation that anchors it to the plasma membrane, it is reasonable to hypothesize that statin therapy interferes with IL-6 signaling in hepatocytes by suppressing the isoprenylation of Rac-1; a decrease in the transcription of CRP would be a likely consequence of this effect. Whether or not a reduction in elevated CRP is directly beneficial to vascular health, statins can exert direct effects on vascular endothelial function that should help prevent vascular inflammation and thrombosis, and thus should be of particular benefit to subjects - such as those with high CRP levels - who are at high risk for vascular events.

Strong decrease of high sensitivity C-reactive protein with high-dose atorvastatin in patients with type 2 diabetes mellitus

OBJECTIVE

Statins are known to reduce CRP concentrations, but whether high doses are more effective is not known.

METHODS

In a prospective double-blind multicenter study in 186 DM2 patients without manifest coronary artery disease and with dyslipidemia, the effect of a 30-week treatment with 10 and 80 mg atorvastatin or placebo on the reduction of hs-CRP levels was measured.

RESULTS

Median CRP levels increased with 6.6% in the placebo group and were reduced by 15 and 47%, respectively, with atorvastatin 10 and 80 mg (P<0.001; significantly different from 10 mg atorvastatin and from placebo (P<0.001). Variation in IL-6 and plasma lipids associated for 21 and 8%, respectively, with variation in CRP levels (P<0.001 and P=0.01). Of patients with a baseline CRP level above an arbitrary threshold of 3.0 mg/l, 56% in the 80 mg atorvastatin group reached a level of less than 3.0 mg/l, versus 23% randomized to 10 mg atorvastatin (P<0.01) and 17% in the placebo group (P<0.005).

CONCLUSIONS

In DM2 patients high dose atorvastatin induced a strong reduction in CRP levels. The decrease in CRP was mainly independent of effects on lipid lowering and changes in IL-6 levels. The pleiotropic effect of high-dose atorvastatin on inflammation could add to its cardioprotective effect in high-risk patients.

Interleukin-6 -174G>C polymorphism and risk of coronary heart disease in West of Scotland coronary prevention study (WOSCOPS)

Interleukin (IL)-6 plays an important role in the pathogenesis of coronary heart disease (CHD). Two functional polymorphisms in the IL-6 promoter have been identified (-174G>C and -572G>C), with both the rare alleles being associated with higher plasma levels of IL-6 after bypass surgery and one of them (-174G>C) associated with CHD risk. We have studied the contribution of these polymorphisms to CHD risk in the West of Scotland Coronary Prevention Study (WOSCOPS), a primary prevention trial that demonstrated the effectiveness of pravastatin in reducing morbidity and mortality from CHD. Four hundred ninety-eight cases (consisting of individuals experiencing a cardiovascular event during 4.8 years of follow-up) and 1109 controls (individuals matched for age and smoking habits) were genotyped. In the placebo group, there was no significant evidence of higher risk associated with the -174CC genotype compared with the GG+GC group. However, in the pravastatin-treated group, CC homozygotes had a significantly lower risk of CHD compared with the GG+GC placebo group (odds ratio 0.46, 95% CI 0.27 to 0.79), and this remained statistically significant after adjustment for classic risk factors. Compared with the GG+GC group, men with the CC genotype had modestly, but not significantly, higher baseline levels of IL-6, C-reactive protein, or fibrinogen but showed a significantly greater fall in LDL cholesterol with statin treatment (P=0.036). The -572G>C polymorphism was not significantly associated with any plasma trait or CHD risk. Thus, in subjects under pravastatin treatment, the -174CC genotype was associated with a lower risk of CHD. These results demonstrate the importance of the inflammatory system in determining the risk of CHD and support the nonlipid effect of statins on risk.

Current practice in the treatment of hyperlipidaemias

Primary and secondary prevention trials for coronary heart disease (CHD) in hyperlipidaemic or so-called 'normolipidaemic' patients with drugs affecting lipid metabolism have clearly confirmed that even slight alterations in lipoprotein metabolism are major risk factors for CHD. The global cardiovascular risk must be determined before deciding to treat patients with drugs affecting lipid metabolism. Screening for dyslipidaemia consists of determining cholesterol (C), LDL-cholesterol (LDL-C), HDL-cholesterol (HDL-C) and triglyceride (TG) plasma levels and the decision to treat depends mainly on LDL-C plasma levels. Furthermore, secondary dyslipidaemia must be diagnosed and primary disease must be adequately treated. There are four classes of available lipid-regulating drugs: HMG-CoA reductase inhibitors (statins), bile acid sequestrants (resins), peroxisome proliferator-activated receptor-alpha (PPAR- alpha) activators (fibrates) and nicotinic acid. All four will be discussed in this review. Clinical trials have shown that drugs improving lipid metabolism reduce CHD relative risk from 24% (secondary prevention) to 37% (primary prevention) and the absolute risk from 2% (primary prevention) to 8.5% (secondary prevention). These studies indicate that the number of patients needed to be treated to economise one clinical event ranges from 12 (secondary prevention) to 50 (primary prevention). Clinical trials are currently testing the hypothesis that 'lower LDL-C is better'.