Effects of lovastatin therapy on susceptibility of LDL to oxidation during alpha-tocopherol supplementation

Statins and foam cell formation: Impact on LDL oxidation and uptake of oxidized lipoproteins via scavenger receptors

The uptake of oxidized lipoproteins via scavenger receptors and the ensuing formation of foam cells are key events during atherogenesis. Foam cell formation can be reduced by treatment with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins). The efficacy of statins is evidently due not only to their cholesterol-lowering properties, but also to lipid-independent pleiotropic effects. This review focuses on lipid-independent pleiotropic effects of statins that influence foam cell formation during atherogenesis, with special emphasis on oxidative pathways and scavenger receptor expression.

Dietary antioxidants in preventing atherogenesis

Several naturally occurring constituents have received considerable attention because of their potential antioxidant activity. Consuming a diet rich in natural antioxidants has been associated with prevention from and/or treatment of atherosclerosis. Bioactive components of food, which are of special interest, include the Vitamins E and C, polyphenols, carotenoids-mainly lycopene and beta-carotene, and coenzyme Q10, featured by antioxidant properties. Antioxidant therapy is supposed to be effective in the early stages of atherosclerosis by preventing LDL oxidation and the oxidative lesion of endothelium. This review focuses on the effect of dietary antioxidants pertained to LDL oxidation and to the vascular endothelial dysfunction. Now that the human genome has been completely sequenced, genetic factors involved in oxidation may open new horizons to identify persons at risk for cardiovascular disease, allowing effective dietary intervention strategies to recover normal homeostasis and to prevent diet-related implications. On this basis, current studies on the action of selected antioxidant nutraceuticals on the activity of transcription factors, such as final targets in the signal transduction cascade and gene regulation, may emerge into new treatment concepts.

Statins: panacea for sepsis?

Sepsis occurs when the immune system responds to a localised infection at a systemic level, thereby causing tissue damage and organ dysfunction. Statins have proven health benefits in many diseases involving vascular inflammation and injury. Recent animal data suggest that the administration of a statin before a sepsis-inducing insult reduces morbidity and improves survival. The immunomodulatory and anti-inflammatory effects of statins, collectively referred to as pleiotropic effects, lend biological plausibility to such findings. Limited human data hint at reduced mortality rates in bacteraemic patients, and a reduced risk of sepsis in patients with bacterial infections concurrently taking statins. These lines of evidence point to a potential new treatment and prevention modality for sepsis. The stage is set for randomised controlled clinical trials that will determine whether statins represent a safe and beneficial treatment in critically ill, septic patients and whether statins are effective at preventing sepsis in high-risk clinical settings.

Randomized trial of the effects of simvastatin on cognitive functioning in hypercholesterolemic adults

PURPOSE

In our initial study of the potential effects of cholesterol-lowering interventions on cognitive functioning, treatment with lovastatin as compared with placebo caused performance decrements on several neuropsychological tests, whereas scores on other tests were unaffected. The current study was designed to confirm and extend those findings.

METHODS

The study comprised 308 hypercholesterolemic adults between 35 and 70 years of age. Employing a randomized double-blind design, we assigned participants to daily treatment with placebo, 10 mg of simvastatin, or 40 mg of simvastatin for 6 months. A neuropsychological test battery was administered to assess cognitive functioning at baseline and at the end of the treatment period.

RESULTS

A total of 283 subjects completed the study: 94 subjects on placebo, 96 taking 10 mg of simvastatin, and 93 taking 40 mg of simvastatin. Compared with placebo, decremental effects of simvastatin treatment were found on tests previously observed to be sensitive to statins (P = 0.008; difference in summary z scores = 0.18; 95% confidence interval [CI]: 0.07 to 0.29) and on tests not previously administered (P = 0.04; difference in summary z scores = 0.17; 95% CI: 0.05 to 0.29), but not on tests previously observed to be insensitive to statins (P = 0.84; difference in summary z scores = 0.02; 95% CI: -0.07 to 0.10). For the three tests specifically affected by simvastatin, effects on cognitive performance were small, manifest only as failure to improve during the 6 months of treatment (compared with placebo), and were confounded by baseline differences on one test.

CONCLUSION

This study provides partial support for minor decrements in cognitive functioning with statins. Whether such effects have any long-term sequelae or occur with other cholesterol-lowering interventions is not known.

Effects of d-003, a new hypocholesterolaemic and antiplatelet compound, on lipid profile and lipid peroxidation in healthy volunteers

BACKGROUND

D-003 is a mixture of long-chain aliphatic primary acids purified from sugarcane wax with hypocholesterolaemic effects proven in rabbits and healthy volunteers; it lowers serum total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C) and increases high-density lipoprotein-cholesterol (HDL-C). D-003 also prevents lipoprotein lipid peroxidation in experimental models.

OBJECTIVE

To investigate the effects of D-003 on lipid profile and lipid peroxidation in healthy human volunteers.

PARTICIPANTS

Forty-six healthy volunteers (24 women, 22 men).

METHODS

This double-blind, randomised, placebo-controlled study investigated the effects of D-003 at 5 and 10 mg/day on the susceptibility of LDL to lipid peroxidation induced by copper ions in healthy volunteers. Forty-six individuals were randomised (1 : 2) to placebo or D-003 at 5 or 10 mg/day, the tablets being taken once a day with the evening meal for 8 weeks. Laboratory determinations and physical examination were performed at baseline and after 4 and 8 weeks of therapy, and compliance and adverse experience assessments were performed at weeks 4 and 8.

RESULTS

All groups were well matched at baseline. At study completion, D-003 at 5 and 10 mg/day significantly (p < 0.001) lowered LDL-C, the primary response variable, by 20.8% and 28.8%, respectively. In addition, D-003 at 5 and 10 mg/day reduced (p < 0.001) TC (12.7% and 17.5%, respectively), LDL-C/ HDL-C (25.9% and 36.3%, respectively) and TC/HDL-C (18.6% and 26.3%, respectively), while significantly (p < 0.01) increasing HDL-C (7.7% and 12.4%, respectively). Triglycerides were significantly (p < 0.05) reduced (8.8% and 13.1%, respectively) with respect to baseline, but not versus placebo. Responses assessed at 4 weeks showed significant reductions of LDL-C, TC and atherogenic ratios with both doses of D-003, whereas HDL-C was significantly increased. Triglycerides, however, remained unchanged. No significant changes in any lipid profile variable occurred in the placebo group. D-003 at 5 and 10 mg/day significantly (p < 0.05) increased lag time (18.3% and 32.0%, respectively) and decreased maximum rate of diene propagation (V(max)) [12.7% and 19.1%, respectively] of copper-induced LDL peroxidation. D-003 5 and 10 mg/day attenuated the reduction of the reactivity against 2, 4, 6-trinitrobenzene sulfonic acid (TNBS) by 19.9% and 32.0%, respectively. The treatment was well tolerated. Three subjects (one from each group) discontinued the study. Only one, treated with D-003 5 mg/day, discontinued because of an adverse event (gastritis).

CONCLUSIONS

D-003 at 5 and 10 mg/day demonstrated dose-dependent cholesterol-lowering effects in healthy volunteers characterised by reductions in LDL-C, TC and atherogenic ratios, and increases in HDL-C. Effects on triglycerides were modest and uncertain. As expected from experimental studies, D-003 inhibited the susceptibility of LDL to lipid peroxidation assessed by three indicators lag time V(max) and reactivity versus TNBS. Further studies investigating the effect of larger doses and treatment duration must be conducted to confirm the reproducibility of the present results in different study populations.

Susceptibility to oxidation of plasma low-density lipoprotein in X-linked adrenoleukodystrophy: effects of simvastatin treatment

This paper shows for the first time the higher oxidizability of low-density lipoprotein (LDL) in plasma from adrenoleukodystrophy (ALD) patients compared to that of control subjects. LDL oxidation susceptibility was assessed by conjugate diene formation, hydroperoxide and lipoperoxide formation, and electrophoretic mobility. Simvastatin therapy, an HMG-CoA reductase inhibitor, seems to be a protective pharmacological agent against the higher oxidizability of LDL in plasma from ALD patients.

Comparison of LDL trap assay to other tests of antioxidant capacity; effect of vitamin E and lovastatin treatment

Oxidized low density lipoprotein (LDL) has a major impact in the development of atherosclerosis. Risk for oxidative modification of LDL is usually determined indirectly by measuring the capability of LDL to resist radical insult. We compared three different methods quantifying the antioxidative capacity of LDL ex vivo in dyslipidemic patients with coronary heart disease. Plasma samples were obtained from two double-blinded cross-over trials. The duration of all interventions (placebo, lovastatin 60 mg/day, RRR-alpha-tocopherol 300 mg/day and lovastatin + RRR-alpha-tocopherol combined) was 6 weeks. The total radical capturing capacity of LDL (TRAP) in plasma was determined using 2,2-azo-bis(2,4-dimethyl-valeronitrile) (AMVN) -induced oxidation, and measuring the extinction time of chemiluminescence. TRAP was compared to the variables characterizing formation of conjugated dienes in copper-induced oxidation. Also the initial concentrations and consumption times of reduced alpha-tocopherol (alpha-TOH) and ubiquinol in AMVN-induced oxidation were determined. Repeatability of TRAP was comparable to that of the lag time in conjugated diene formation. Coefficient of variation within TRAP assay was 4.4% and between TRAP assays 5.9%. Tocopherol supplementation produced statistically significant changes in all antioxidant variables except those related to LDL ubiquinol. TRAP increased by 57%, the lag time in conjugated diene formation by 34% and consumption time of alpha-TOH by 88%. When data of all interventions were included in the analyses, TRAP correlated with the lag time (r = 0.75, p < 10(-6)), with LDL alpha-TOH (r = 0.50, p < 0.001) and with the consumption time of alpha-TOH (r = 0.58, p < 0.0001). In the baseline data, the associations between different antioxidant variables were weaker. TRAP correlated with the lag time (r = 0.55, p < 0.001) and alpha-TOH consumption time (r = 0.48, p < 0.05), and inversely with apolipoprotein Al (r = -0.51, p < 0.05). Lag time at the baseline did not correlate with ubiquinol or tocopherol parameters, or with any plasma lipid or lipoprotein levels analyzed. Lovastatin treatment did not significantly affect the antioxidant capacity of LDL. In conclusion, TRAP reflects slightly different properties of LDL compared to the lag time. Thus, LDL TRAP assay may complement the other methods used to quantify the antioxidant capacity of LDL. However, TRAP and the lag time react similarly to vitamin E supplementation.