CLINICAL RESEARCH: STATINS AND HYPERCHOLESTEROLEMIA
The Influence of Pravastatin and Atorvastatin on Markers of Oxidative Stress in Hypercholesterolemic Humans
Bonnie Ky, MD*,
Anne Burke, MD*,
Sotirios Tsimikas, MD ,
Megan L. Wolfe, BS*,
Mahlet G. Tadesse, ScD*,
Philippe O. Szapary, MD*,
Joseph L. Witztum, MD,
Garret A. FitzGerald, MD* and
Daniel J. Rader, MD*,*
* Institute for Translational Medicine and Therapeutics, University of Pennsylvania, Philadelphia, Pennsylvania
University of California San Diego, La Jolla, California.
Manuscript received September 28, 2007;
revised manuscript received January 24, 2008,
accepted January 29, 2008.
* Reprint requests and correspondence: Dr. Daniel J. Rader, University of Pennsylvania, 421 Curie Boulevard, Room 654 BRB, Philadelphia, Pennsylvania 19104-6160. (Email: rader{at}mail.med.upenn.edu).
 |
Abstract
|
|---|
Objectives: The aim of this study was to determine the effects of pravastatin and atorvastatin on markers of oxidative stress in plasma.
Background: Hydroxymethylglutaryl coenzyme A reductase inhibitors reduce low-density lipoprotein cholesterol (LDL-C) and cardiovascular risk, but their effects on circulating biomarkers of oxidative stress are not well-defined.
Methods: Hypercholesterolemic subjects (n = 120, ages 21 to 80 years with LDL-C 130 to 220 mg/dl) were randomized in a double-blind, parallel design to pravastatin 40 mg/day (prava40), atorvastatin 10 mg/day (atorva10), atorvastatin 80 mg/day (atorva80), or placebo. At baseline and 16 weeks, urinary isoprostanes (8, 12-iso-iPF2 -VI isoform), plasma lipoprotein-associated phospholipase A2 (Lp-PLA2), Mercodia oxidized LDL (OxLDL) with antibody 4E6, oxidized phospholipids/apolipoprotein B-100 particle (OxPL/apoB) with antibody E06, immunoglobulin (Ig)G/IgM autoantibodies to malondialdehyde (MDA)-LDL, and apolipoprotein B (apoB)-immune complexes (IC) were measured.
Results: After 16 weeks, there were no significant changes in urinary 8, 12-iso-iPF2-VI. The Lp-PLA2 and OxLDL were reduced in statin-treated groups, but after adjusting for apoB, only prava40 led to a reduction in Lp-PLA2 (–15%, p = 0.008) and atorva10 to a decrease in OxLDL (–12.9%, p = 0.01). The OxPL/apoB increased 25.8% (p < 0.01) with prava40 and 20.2% (p < 0.05) with atorva80. There were no changes in MDA-LDL autoantibodies, but significant decreases in IC were noted.
Conclusions: This study suggests that statin therapy results in variable effects on oxidative stress markers in hypercholesterolemic subjects. Future outcome studies should collectively assess various oxidative markers to define clinical utility.
|
Abbreviations and Acronyms
| | atorva10 = atorvastatin 10 mg/day | | atorva80 = atorvastatin 80 mg/day | | CHD = coronary heart disease | | ELISA = enzyme-linked immunosorbent assay | | HDL-C = high-density lipoprotein cholesterol | | IC = immune complexes | | LDL-C = low-density lipoprotein cholesterol | | Lp(a) = lipoprotein(a) | | Lp-PLA2 = lipoprotein-associated phospholipase A2 | | MDA = malondialdehyde | | OxLDL = oxidized low-density lipoprotein | | OxPL = oxidized phospholipids | | OxPL/apoB = oxidized phospholipids onapolipoprotein B-100 particles | | prava40 = pravastatin 40 mg/day | | TC = total cholesterol |
|
Hydroxymethylglutaryl coenzyme A reductase inhibitors (statins) are highly effective at reducing plasma levels of low-density lipoprotein cholesterol (LDL-C) and significantly decrease cardiovascular risk (1). The concept that statins have other cellular effects not directly related to low-density lipoprotein (LDL) lowering has been gaining increasing attention (2). One of the proposed pleiotropic effects of statins is a reduction of oxidative stress. In vitro tissue culture studies have demonstrated that statins reduce reactive oxygen species generation (3,4). Animal studies have suggested that statins decrease vascular reactive oxygen species production independent of cholesterol reduction (5–7).
Well-controlled human studies addressing this hypothesis are less common. One study suggested that statin therapy reduced ex vivo platelet reactive oxygen species production (8). An uncontrolled study in hypercholesterolemic subjects treated with atorvastatin 10 mg/day for 12 weeks indicated that atorvastatin reduced plasma levels of nitrotyrosine and other myeloperoxidase-derived and nitric oxide-derived markers (9). Smaller studies have suggested that statin therapy might reduce the urinary excretion (10) or plasma levels of the isoprostane 8-iso-IPF2-III (11).
Several important questions remain regarding the impact of statins on oxidative stress. First, many of the aforementioned studies were not well controlled and require confirmation with rigorous methodology. Second, the question of statin dose-response on oxidative stress has not been addressed. Indeed, the TNT (Treating to New Targets) trial demonstrated that coronary heart disease (CHD) patients randomized to atorvastatin 80 mg daily had fewer cardiovascular events than those treated with atorvastatin 10 mg (12), indicating a dose-response with regard to clinical outcome. A similar dose-response with regard to oxidative stress would help support this as a mechanism of benefit. Finally, equivalent doses of statins have never been compared with each other in a human study with regard to effects on oxidative stress. The clinical trials REVERSAL (Reversal of Atherosclerosis With Aggressive Lipid Lowering) (13) and PROVE-IT (Pravastatin or Atorvastatin Evaluation and Infection Therapy) (14) compared pravastatin 40 mg to atorvastatin 80 mg and suggested that the latter was more effective with regard to inhibition of coronary atheroma progression as well as reduction in clinical events. A comparison of these statins at the same doses and their effects on oxidative stress would be of substantial interest.
We performed a randomized, parallel-arm, double-blind, placebo-controlled trial of pravastatin 40 mg and 2 different doses of atorvastatin, 10 mg and 80 mg, with the aim of assessing oxidative stress with a diversified repertoire of biomarkers.
|
Methods
|
|---|
Subjects.
One hundred twenty healthy subjects, between the ages of 21 and 80 years, with a baseline LDL-C between 130 and 220 mg/dl on no lipid-lowering therapy were recruited. Approval from the Institutional Review Board was obtained. Participants were recruited through the University of Pennsylvania Health System and local advertising from January 2001 to June 2002. Exclusion criteria included exposure to cholesterol-modulating drugs and supplements within the previous 6 weeks, known CHD, diabetes or fasting glucose >126 mg/dl at the screening visit, significant renal or hepatic disease (alanine aminotransferase [ALT] or aspartate aminotransferase [AST] >1.5 x the upper limits of normal), triglycerides >500 mg/dl, familial hypercholesterolemia, and pregnant or lactating women.
Study design.
The screening visit consisted of a questionnaire, fasting blood work, and an electrocardiogram. Eligible subjects were asked to return 7 to 14 days after the initial visit for a pretreatment visit (Fig. 1). Seven to 10 days after this, patients returned for randomization in a 1:1:1:1 scheme to either receive pravastatin 40 mg/day (prava40), atorvastatin 10 mg/day (atorva10), atorvastatin 80 mg/day (atorva80), or placebo. Study assessments took place after 8 and 16 weeks of therapy. Data obtained at each subsequent visit included fasting blood work, 12-h urine collection, adverse event reporting, and study medication return to assess compliance. Laboratory analyses of blood work included complete chemistry and lipid analyses and assessment of biomarkers.
Laboratory measurements.
Lipid parameters were analyzed from ethylenediaminetetraacetic acid plasma collected after a 12-h fast in a Centers for Disease Control–standardized lipid laboratory. Plasma total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and triglyceride (TG) levels were measured enzymatically on a Cobas Fara II autoanalyzer (Roche Diagnostic Systems Inc., Branchburg, New Jersey) with Sigma reagents (Sigma Chemical Co., St. Louis, Missouri). The LDL-C and very-low-density lipoprotein cholesterol levels were determined after ultracentrifugation at a density of 1.006 g/ml. Apolipoprotein B (apoB) was measured with Wako reagents (Wako Pure Chemical Industries, Ltd., Osaka, Japan).
Concentrations of oxidized LDL (OxLDL) were assayed with the noncompetitive Mercodia immunoassay, which uses an antibody that was obtained after immunization of mice with copper-oxidized LDL (15), and primarily detects malondialdehyde LDL (MDA-LDL). The intra- and interassay coefficients of variation (CV) for this assay were 10% to 15%. The lipoprotein associated phospholipase A2 (Lp-PLA2) was measured with an enzyme-linked immunoassay from Diadexus (16) with intra- and interassay CV that were  10%. The assays for the oxidized phospholipids (OxPL) on apoB-100 (OxPL/apoB), immunoglobulin (Ig) G, and IgM immune complexes (IC/apoB) and MDA-LDL were performed at the University of California at San Diego. The content of OxPL/apoB was measured by chemiluminescent enzyme-linked immunosorbent assay (ELISA) with the murine monoclonal antibody E06, which binds to the phosphorylcholine headgroup of oxidized but not native phospholipids (17–19). Equal numbers of apoB-100 particles are captured from each plasma sample and the content of oxPL is normalized for apoB-100 in each subject. The "apoB" measure depicted in the denominator of the oxPL/apoB ratio is not the plasma apoB-100 level but represents the amount of apoB-100 captured on each microtiter well. Chemiluminescence ELISAs were used to measure IgG and IgM autoantibodies to MDA-LDL and IgG and IgM apoB-100-immune complexes (apoB-IC) (17–19). All oxPL values are expressed as relative light units (RLU) measuring the emission of light over 100 ms with the chemiluminescent ELISA. The CV for OxPL/apoB and autoantibody titer assays were 6% to 10% (19) and for apoB 2.4% (20). Lipoprotein(a) [Lp(a)] was measured with monoclonal antibody LPA4 as previously described; the intra- and interassay CV were 3.6% to 6.3% (20).
The data for OxPL/apoB were analyzed and presented as previously described (17–19). The OxPL/apoB and IC/apoB quantifies the content of OxPL and IC on each captured apoB-100 particle. Total apoB-IC reflects the IC content on all apoB-100–containing particles in the plasma. This value is obtained by multiplying the ELISA IC/apoB values (in relative light units) by the plasma apoB-100 levels.
8, 12-iso-iPF2-VI, the most abundant isoprostane detected in human urine, was measured as previously described (21). Total lipids from urine were extracted with ice-cold Folch solution, chloroform/methanol (2:1, volume/volume). After removing aliquots for phospholipid measurement, the organic phase was dried under nitrogen. The samples were hydrolyzed by the addition of aqueous potassium hydroxide (KOH) (15%), and 8, 12-iso-iPF2-VI was measured with an O18 labeled internal standard in a selected ion monitoring assay based on tandem mass spectrometry. The measurements were normalized to milligrams of urinary creatinine and expressed as ng/mg creatinine (Cr). The intra- and interassay CV ranged from 2.3% to 5.4% (22).
All safety labs were measured with standard methods at the Hospital of the University of Pennsylvania clinical laboratory.
Statistical analysis.
Student paired t tests were used for within group comparisons, and 1-way analysis of variance (ANOVA) was used for between group comparisons for normally distributed variables, such as TC and LDL-C. Comparisons between groups were performed with ANOVA with the Bonferroni correction to adjust for multiple comparisons. Non-normally distributed variables, such as urinary 8, 12-iso-iPF2-VI, were analyzed with Wilcoxon signed-rank tests for within group comparisons and Kruskal-Wallis tests for between group comparisons. Baseline and 16 week values were also log transformed, and ANOVA was used for between group comparisons. Medians were calculated, and interquartile ranges (IQRs) were also analyzed. Multivariable linear regression models were developed to assess the relative changes in isoprostane levels across treatment groups, with relative change defined as the difference in 8, 12-iso-iPF2-VI at week 16 and baseline divided by the baseline value, to account for baseline differences. Adjustments were made for gender, smoking, and exercise.
Linear regression models were fit to assess the effects of treatments on the percent change in various lipid markers. The effects of the 3 treatment arms were assessed relative to the percent changes in the placebo group. The placebo group was used as the reference, and 3 indicator variables were introduced for each of the treatment arms. Because the percent changes in many of these lipid markers are related to percent changes in LDL-C and apoB, adjusted models that corrected for these factors were fit.
This study was designed to detect a 20% difference in 8, 12-iso-iPF2-VI between the prava40 and placebo group. Analyses were performed in STATA 8.0 (Stata Corp., College Station, Texas).
|
Results
|
|---|
Baseline characteristics and study completion.
After the 4-week dietary run in, 120 patients were randomized to 1 of 4 treatment groups as shown in Figure 1. The baseline characteristics of participants are shown in Table 1. There were no significant differences across the 4 arms. Over the course of the study, there were 3 drop-outs from the placebo group, 6 from the prava40, 1 from the atorva10, and 4 from the atorva80 group (p = 0.22). The reasons for withdrawal were primarily for personal (6 of 14) or technical reasons (4 of 14), although 4 were for side effects.
Lipid parameters.
There were no significant differences in baseline lipid values among the groups. The placebo group had no significant changes in plasma lipids. As expected, all statin-treated groups experienced significant reductions in TC, LDL-C, apoB, and non–HDL-C (Table 2). Specifically, atorva80 reduced LDL-C by 42% compared with 31% in the atorva10 and 26% in the prava40 groups. There were no statistically significant differences between the prava40 and atorva10 groups in any of the lipoprotein parameters measured.
All 3 statin doses resulted in a significant increase in Lp(a) levels, ranging from 12% to 26%, as has been noted previously (17,23). There was also a small increase in the placebo group, perhaps due to a diet effect, as was also noted previously (Table 2) (24).
Urinary 8, 12-iso-iPF2-VI.
At baseline and 16 weeks, there was no significant difference in the log transformed excretion of the F2 isoprostane across the 4 treatment groups (p = 0.08 and 0.47, respectively) (Table 3).
View this table:
[in this window]
[in a new window]
|
Table 3 Median Urinary 8, 12-iso-IPF2-VI Isoprostane Levels at Baseline and After 16 Weeks of Statin Therapy and Summary of Relative Changes
|
|
When multivariable linear regression models were used to assess the effects of treatment group on the relative change in urinary 8, 12-iso-iPF2-VI, there was no significant effect by treatment (r2 = 0.03, p = 0.36). When the model was refitted with individual adjustments for gender (r2 = 0.04, p = 0.47), smoking (r2 = 0.05, p = 0.30), and exercise (r2 = 0.03, p = 0.53), there was again no effect by treatment group. When the analysis was stratified by subjects with baseline levels above the median (>3.39 ng/mg Cr) as well as those in the highest quartile (>4.86 ng/mg Cr), potentially reflecting those subjects with a higher degree of oxidant stress, there remained no significant effect.
Oxidized LDL (Mercodia assay).
There were no significant differences in baseline OxLDL, with the median OxLDL ranging from 84 to 93 mg/dl (p = 0.84) (Fig. 2A). After 16 weeks, all statin-treated groups experienced a reduction in OxLDL (p < 0.001 for overall differences). The corresponding percent changes in OxLDL were: 3.7% for placebo, –22.5% for pravastatin, –32.4% for atorva10, and –36.3% for atorva80 (p < 0.001 for all variables except placebo, p = 0.30). In multivariable linear regression analysis, this change was still significant in the atorvastatin-treated groups after accounting for the percent change in LDL-C (–16.9% and –15.2% difference for atorva10 [p = 0.003] and atorva80 [p = 0.02], respectively). However, only the percent change in atorva10 (–12.9%) remained statistically significant after apoB changes were considered (p = 0.01).
View larger version (24K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2 Changes in OxLDL, Lp-PLA2, and ApoB-100 After Statin Therapy
(A) Changes in oxidized low-density lipoprotein cholesterol (OxLDL) after statin therapy as measured by the Mercodia assay. Mean Mercodia OxLDL (antibody 4E6) levels (mg/dl) at baseline and 16 weeks in placebo-, pravastatin 40 mg/day (prava40)-, atorvastatin 10 mg/day (atorva10)-, and atorvastatin 80 mg/day (atorva80)-treated groups. (B) Changes in lipoprotein-associated phospholipase A2 (Lp-PLA2) mass after statin therapy. Mean Lp-PLA2 mass (ng/ml) at baseline and 16 weeks in placebo-, prava40-, atorva10-, and atorva80-treated groups. (C) Changes in apolipoprotein B-100 particle (apoB-100) after statin therapy. Mean apoB-100 levels (mg/dl) at baseline and 16 weeks in placebo-, prava40-, atorva10-, and atorva80-treated groups.
|
|
Lp-PLA2.
Both pravastatin and atorvastatin led to significant decreases in Lp-PLA2 mass (Fig. 2B). All 3 therapies led to an approximate 20% decrease in this parameter after 16 weeks of therapy. In the placebo group, there was a nonsignificant 4% increase. However, Lp-PLA2 mass correlated strongly with LDL-C and apoB levels, and when changes in LDL-C were accounted for, only atorva10 and prava40 remained significant, with an approximate 14% decrease (p = 0.02 for both). When changes in apoB were accounted for, only the decrease in Lp-PLA2 mass for subjects treated with prava40 remained statistically significant with a 15% reduction (p = 0.008). Figure 2C demonstrates the corresponding changes in apoB levels, which show similar trends to changes in OxLDL and Lp-PLA2.
OxPL/apoB assay.
There were no statistically significant differences in OxPL/apoB at baseline. However, after 16 weeks of statin therapy, significant increases were noted across the 3 groups (p = 0.005 by ANOVA), with prava40 demonstrating a 25.8% mean percent increase from baseline (p < 0.01) and atorva80 demonstrating a 20.2% increase in OxPL/apoB (p < 0.05), which were statistically significant. No significant changes were noted in atorva10 (+8.0%, p > 0.05) or placebo (–2.1%, p > 0.05) (Fig. 3A). In the statin-treated groups, Lp(a) increased significantly in parallel with OxPL/apoB: prava40 (26%, p < 0.001), atorva10 (12%, p < 0.001), atorva80 (26%, p = 0.005) (Fig. 3B).
View larger version (29K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3 Changes in OxPL/apoB and Lp(a) After Statin Therapy
(A) Changes in oxidized phospholipids/apolipoprotein B-100 particle (OxPL/apoB) after statin therapy. Mean percent change in OxPL/apoB levels (antibody E06) after 16 weeks in placebo-, prava40-, atorva10-, and atorva80-treated groups. (B) Changes in lipoprotein(a) [Lp(a)] after statin therapy. Mean percent change in Lp(a) after 16 weeks in placebo-, prava40-, atorva10-, and atorva80-treated groups. Abbreviations as in Figure 2.
|
|
Autoantibodies to MDA-LDL and apoB immune complexes.
There were no statistically significant differences in MDA-LDL autoantibodies or IC formation at baseline. After 16 weeks of statin therapy there were no significant changes in IgG or IgM autoantibodies to MDA-LDL or IgG or IgM IC/apoB (Fig. 4). However, all 3 statin-treated arms led to a trend in reduction in total apoB-IC content (Fig. 5). Total apoB-IC IgG decreased by 12% with 10 mg of atorvastatin therapy (p = 0.02) and 22% with atorva80 (p < 0.001) as compared with baseline. Atorva80 also led to a statistically significant reduction in the total apoB-IC IgM (30%), as did prava40 (18%) (p < 0.001 for both). This was driven by changes in apoB levels in the statin-treated groups.
View larger version (21K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 4 Changes in IC/apoB and MDA-LDL Autoantibodies After Statin Therapy
Mean percent change in immune complex (IC)/apoB formation and immunoglobulin (Ig)G and IgM malondialdehyde (MDA)-LDL autoantibodies after 16 weeks in placebo-, prava40-, atorva10-, and atorva80-treated groups. Abbreviations as in Figure 2.
|
|
Correlation between markers of oxidative stress at baseline.
Mercodia OxLDL correlated strongly with apoB (r2 = 0.56, p < 0.001) and LDL-C (r2 = 0.46, p < 0.001) at baseline (Table 4). There was a slight inverse correlation between total apoB-IC IgG and IgM with LDL and apoB as well as between IgM and OxLDL, which were all on the order of r2 = –0.20 (p = 0.03 for LDL and total apoB-IC IgG, apoB and total apoB-IC IgM; p = 0.04 for remainder).
View this table:
[in this window]
[in a new window]
|
Table 4 Correlation (r2) Between Baseline Levels of Lipoproteins and Associated Parameters and Markers of Oxidative Stress
|
|
Correlation between changes in markers of oxidative stress after statin therapy.
Changes in Mercodia OxLDL strongly correlated with changes in apoB (r2 = 0.76, p < 0.001), LDL-C (r2 = 0.68, p < 0.001), and Lp-PLA2 (r2 = 0.48, p < 0.001). Changes in Lp-PLA2 correlated strongly with changes in apoB (r2 = 0.44, p < 0.001) and LDL-C (r2 = 0.47, p < 0.001). Changes in OxPL/apoB did not correlate with changes in LDL-C (r2 = –0.14, p = 0.16) and had slight inverse correlations with changes in Mercodia OxLDL (r2 = –0.23, p = 0.02), Lp-PLA2 (r2 = –0.24, p = 0.017), and apoB (r2 = –0.22, p = 0.03) (Table 5). A strong correlation was also noted between changes in OxPL/apoB and Lp(a) (r2 = 0.62, p < 0.0001).
View this table:
[in this window]
[in a new window]
|
Table 5 Correlation (r2) Between Changes in Levels of Lipoproteins and Associated Parameters and Markers of Oxidative Stress After Statin Therapy
|
|
|
Discussion
|
|---|
In this study of hypercholesterolemic subjects, we found that statins reduced LDL-C and non–HDL-C as expected but had variable effects on levels of several distinct biomarkers of oxidative stress. In this relatively small study, these markers did not provide a consistent reflection of an antioxidant effect of statins.
Isoprostanes, when measured by sensitive and specific methodology based on mass spectrometry, are believed to be very sensitive and reliable measures of lipid peroxidation in vivo (22,25,26). They are generated in situ by the nonenzymatic oxidation of an unsaturated fatty acid at the sn2 position of phospholipids. Once formed through the action of phospholipase, free isoprostanes are transported in the plasma and excreted in the urine. Importantly, although indirect indexes of lipid peroxidation, they are chemically stable anylates (26). They are elevated in states of increased oxidative stress, including tobacco use, hypercholesterolemia, and CHD (27–30). In both animal models and in humans, antioxidant treatment has been shown to decrease elevated isoprostane levels (31,32). Levels of F2 isoprostanes (iPF2-IV) are increased in the urine and aortic tissue of atherosclerotic animals, including apoE and LDL receptor-knockout mice (32). In the BOSS (Biomarkers of Oxidative Stress Study) trial, carbon tetrachloride was administered to rodents and the time- and dose-dependent effects on biomarkers of oxidative stress were measured. Plasma and urinary isoprostanes proved to be both valid and sensitive measures of oxidative stress in this study (33). In humans, isoprostanes as identified by immunohistochemistry were significantly elevated compared with controls in the atherosclerotic plaques of carotid and coronary arteries (26,34,35). The most abundant F2 isoprostane reported in human urine is 8, 12-iso-IPF2-VI. Simvastatin has been shown to decrease excretion of a less abundant isoprostane, IPF2-III, also known as 8-iso-PFG2, in a small study of vascular disease patients; this decrease correlated highly with LDL reduction (10). Another study also reported that serum IPF2-III was depressed by simvastatin (36). However, these studies used less-specific immunoreactive approaches directed at a less-abundant compound that, unlike 8, 12-iso-IPF2-VI, can be formed as a product of cyclooxygenase enzymes as well as an isoprostane (26). Thus, given the choice of anylate, methodology, and sample size, these results are not conclusive of an impact of simvastatin on lipid peroxidation.
There are several possible explanations for the lack of change in isoprostane excretion in our study. The most likely is that statin therapy did not suppress lipid peroxidation in this population. We have previously reported that antioxidant vitamins suppress isoprostanes and other markers of lipid peroxidation in vivo only when endogenous antioxidant defenses are depleted, as reflected by elevated levels of these biomarkers (37). It is possible that an impact of statins might have been evident in a population with more advanced atherosclerotic disease.
In spite of the study randomization, the distribution of smokers varied across the 4 treatment arms, with a greater proportion in the placebo arm (p = 0.43). As is well known, controlled studies have demonstrated that isoprostane generation is elevated in a dose-dependent fashion in cigarette smokers (29,30). However, when multivariable linear regression models were adjusted for disparities in smoking in the current study, there remained no significant difference in the relative change of isoprostanes across groups. Our modest sample size might also have limited our ability to detect statistically significant differences in isoprostane generation in response to statins.
The Mercodia OxLDL assay based on the antibody 4E6 seems to detect MDA-modified apoB (15). Oxidized LDL has been identified by immunohistochemistry to be increased in plaques of coronary arteries of hypercholesterolemic swine (38). There are 2 versions of this assay, a standard and competition assay. Several studies have demonstrated a strong correlation between Mercodia OxLDL assay and LDL-C but with a concern for cross reactivity (39,40). In a recent study, this assay lost its predictive value for cardiovascular events when statistical adjustment for apoB levels was performed (41). Tsouli et al. (42) reported an increase in OxLDL levels when plasma samples were enriched with nonoxidized LDL, suggesting that this assay also detects apoB. In our study, the observed reduction in OxLDL correlated highly with reductions in apoB, with only a modest reduction (–12.9%) in the atorva10 group remaining statistically significant after adjusting for apoB. These data are consistent with prior studies that have shown a direct correlation with reduction in Mercodia OxLDL and changes in apoB levels at baseline and in response to statins (39,43,44). Other studies with MDA-LDL assays using different platforms suggest that statins might reduce MDA-modified LDL levels, but these were of small scale and did not adjust for LDL or apoB (45,46).
The E06 antibody is a murine monoclonal antibody that specifically binds to the phosphorylcholine head group of oxidized phospholipids. The E06 assay does not measure OxLDL per se but the content of OxPL/apoB. A strong correlation exists between OxPL/apoB and Lp(a), primarily owing to the fact that Lp(a) is the main carrier of OxPL in humans (47,48). Thus, OxPL/apoB is also a novel biological measure of Lp(a). The assay is set up to capture all apoB particles from plasma equally with antibody MB47 and then measure OxPL on apoB. It is highly sensitive to the number of OxPL epitopes present on individual particles. The OxPL/apoB levels have been demonstrated to be elevated in acute coronary syndromes, immediately after percutaneous coronary interventions, and in patients with hypertension (18,19,49). Levels have also been shown to be predictive of the presence of coronary disease and peripheral vascular disease (50,51). The Bruneck study, a population-based study of adult men and women, demonstrated that increasing tertiles of OxPL/apoB were significantly associated with increasing hazard ratios of incident cardiovascular events, such as myocardial infarction, stroke, and transient ischemic events (20). Thus, OxPL/apoB seems to serve as a valid measure of cardiovascular disease and risk. Future studies will address whether increases in OxPL/apoB will predict clinical outcomes in therapeutic trials.
In all studies performed to date, including this one, a statistically significant increase in OxPL/apoB has been observed in response to diet or treatment with atorvastatin or pravastatin without a concomitant increase in plasma apoB levels (17,23,24). Although this might seem like a paradoxical finding, because elevated levels of OxPL/apoB are associated with the presence of atherosclerosis, this might represent early regression of disease. For example, during dietary regression induced by switching animals from a high- to low-cholesterol diet, the plasma OxPL/apoB ratio increased significantly, even in animals deficient in Lp(a), whereas the content of OxPL in atherosclerotic plaques essentially disappeared (52). This suggests that during early atherosclerosis regression, the increase in OxPL/apoB levels in plasma might reflect a beneficial effect of diet and perhaps statins on the vessel wall.
In animal models, autoantibodies to OxLDL reflect the underlying atherosclerotic process. A strong correlation has been demonstrated between MDA LDL autoantibody levels and urinary 8, 12-iso-IPF2-VI and atherosclerotic lesion area (53) and with progression and regression of atherosclerosis (54). However, in humans, the data are inconsistent. One showed a decrease in autoantibody levels in coronary disease, whereas other studies in hypercholesterolemic children treated with pravastatin or adult hypertension patients treated with fluvastatin showed no effect or mixed results in patients treated with rosuvastatin (23,55–57). Overall, it does not seem that autoantibodies to OxLDL reflect a consistent effect of statins.
Lipoprotein-associated phospholipase A2 catalyzes the hydrolysis of platelet activating factor (PAF) as well as the cleavage of oxidized phospholipids containing an sn-2 polyunsaturated fatty acyl residue, which are formed during the oxidative modification of LDL (58). Secreted by inflammatory cells, Lp-PLA2 circulates in the plasma bound primarily to LDL (80%), with a small portion also bound to HDL (20%). Lipoprotein-associated phospholipase A2 is believed to be proatherogenic and proinflammatory; levels of Lp-PLA2 have also been shown to have a strong association with cardiovascular risk, as demonstrated in the West of Scotland Coronary Prevention and Atherosclerosis Risk in Communities Studies (59,60). In these studies as well as others (61,62), the reduction in Lp-PLA2 was highly associated with changes in LDL-C. This is not unexpected, because in patients without high Lp(a) levels LDL-C carries most of the Lp-PLA2 mass and activity. However, on an equimolar basis, Lp(a) carries more Lp-PLA2 mass and activity than LDL-C (63). It was recently demonstrated, in support of this relationship, that Lp-PLA2 activity potentiated the increased risk of death and cardiac events that was associated with elevated OxPL/apoB or Lp(a) (20).
Study limitations.
Although this is a prospective study and the first to measure all these oxidative biomarkers in the same subset, it is of modest size. These findings will need to be validated in larger studies.
|
Conclusions
|
|---|
In summary, neither pravastatin 40 mg nor atorvastatin 10 mg or 80 mg reduced the urinary excretion of the major isoprostane 8, 12-iso-IPF2-VI and had variable effects on additional markers of oxidative stress. The results of this study suggest that these distinct biomarkers provide divergent information. Future outcome studies should assess all of the well-accepted oxidative markers in the same dataset, because measuring one particular biomarker might not provide a complete picture of risk or therapeutic effect.
|
Footnotes
|
|---|
This work was supported by grants from Bristol-Myers Squibb, the National Institutes of Health (HL62250 and HL61364), the Clinical and Translational Research Center of the University of Pennsylvania (M01-RR00040), the Fondation Leducq and the General Clinical Research Center, University of California, San Diego, with funding provided by the National Center for Research Resources, M01RR00827, U.S. Public Health Service. Dr. FitzGerald is the McNeill Professor of Translational Medicine and Therapeutics. Dr. Rader is a recipient of a Doris Duke Distinguished Clinical Investigator Award. Steven E. Nissen, MD, MACC, served as Guest Editor for this article.
|
References
|
|---|
1. Gotto Jr AM. Risks and benefits of continued aggressive statin therapy Clin Cardiol 2003;26:III3-III12.[Medline]2. Liao JK, Laufs U. Pleiotropic effects of statins Annu Rev Pharmacol Toxicol 2005;45:89-118.[CrossRef][Web of Science][Medline] 3. Yasunari K, Maeda K, Minami M, Yoshikawa J. HMG-CoA reductase inhibitors prevent migration of human coronary smooth muscle cells through suppression of increase in oxidative stress Arterioscler Thromb Vasc Biol 2001;21:937-942.[Abstract/Free Full Text] 4. Obunike JC, Pillarisetti S, Paka L, et al. The heparin-binding proteins apolipoprotein E and lipoprotein lipase enhance cellular proteoglycan production Arterioscler Thromb Vasc Biol 2000;20:111-118.[Abstract/Free Full Text] 5. Rikitake Y, Kawashima S, Yamashita T, et al. Anti-oxidative properties of fluvastatin, an HMG-CoA reductase inhibitor, contribute to prevention of atherosclerosis in cholesterol-fed rabbits Atherosclerosis 2001;154:87-96.[CrossRef][Web of Science][Medline] 6. Wilson SH, Simari RD, Best PJ, et al. Simvastatin preserves coronary endothelial function in hypercholesterolemia in the absence of lipid lowering Arterioscler Thromb Vasc Biol 2001;21:122-128.[Abstract/Free Full Text] 7. Sumi D, Hayashi T, Thakur NK, et al. A HMG-CoA reductase inhibitor possesses a potent anti-atherosclerotic effect other than serum lipid lowering effects—the relevance of endothelial nitric oxide synthase and superoxide anion scavenging action Atherosclerosis 2001;155:347-357.[CrossRef][Web of Science][Medline] 8. Sanguigni V, Pignatelli P, Caccese D, et al. Increased superoxide anion production by platelets in hypercholesterolemic patients Thromb Haemost 2002;78:796-801. 9. Shishehbor MH, Brennan ML, Aviles RJ, et al. Statins promote potent systemic antioxidant effects through specific inflammatory pathways Circulation 2003;108:426-431.[Abstract/Free Full Text] 10. De Caterina R, Cipollone F, Filardo FP, et al. Low-density lipoprotein level reduction by the 3-hydroxy-3-methylglutaryl coenzyme-A inhibitor simvastatin is accompanied by a related reduction of F2-isoprostane formation in hypercholesterolemic subjects: no further effect of vitamin E Circulation 2002;106:2543-2549.[Abstract/Free Full Text] 11. Lee TM, Chou TF, Tsai CH. Association of pravastatin and left ventricular mass in hypercholesterolemic patients: role of 8-iso-prostaglandin f2alpha formation J Cardiovasc Pharmacol 2002;40:868-874.[CrossRef][Web of Science][Medline] 12. LaRosa JC, Grundy SM, Waters DD, et al. Intensive lipid lowering with atorvastatin in patients with stable coronary disease N Engl J Med 2005;352:1425-1435.[CrossRef][Web of Science][Medline] 13. Nissen SE, Tuzcu EM, Schoenhagen P, et al. Effect of intensive compared with moderate lipid-lowering therapy on progression of coronary atherosclerosis: a randomized controlled trial JAMA 2004;291:1071-1080.[Abstract/Free Full Text] 14. Cannon CP, Braunwald E, McCabe CH, et al. Intensive versus moderate lipid lowering with statins after acute coronary syndromes N Engl J Med 2004;350:1495-1504.[CrossRef][Web of Science][Medline] 15. Holvoet P, Donck J, Landeloos M, et al. Correlation between oxidized low density lipoproteins and von Willebrand factor in chronic renal failure Thromb Haemost 1996;76:663-669.[Web of Science][Medline] 16. Caslake MJ, Packard CJ, Suckling KE, Holmes SD, Chamberlain P, Macphee CH. Lipoprotein-associated phospholipase A(2), platelet activating factor acetylhydrolase: a potential new risk factor for coronary artery disease Atherosclerosis 2000;150:413-419.[CrossRef][Web of Science][Medline] 17. Tsimikas S, Witztum JL, Miller ER, et al. High-dose atorvastatin reduces total plasma levels of oxidized phospholipids and immune complexes present on apolipoprotein B-100 in patients with acute coronary syndromes in the MIRACL trial Circulation 2004;110:1406-1412.[Abstract/Free Full Text] 18. Tsimikas S, Lau HK, Han KR, et al. Percutaneous coronary intervention results in acute increases in oxidized phospholipids and lipoprotein(a): short-term and long-term immunologic responses to oxidized low-density lipoprotein Circulation 2004;109:3164-3170.[Abstract/Free Full Text] 19. Tsimikas S, Bergmark C, Beyer RW, et al. Temporal increases in plasma markers of oxidized low-density lipoprotein strongly reflect the presence of acute coronary syndromes J Am Coll Cardiol 2003;41:360-370.[Abstract/Free Full Text] 20. Kiechl S, Willeit J, Mayr M, et al. Oxidized phospholipids, lipoprotein(a), lipoprotein-associated phospholipase A2 activity and 10-year cardiovascular outcomes. Prospective results from the Bruneck study. Arterioscl Thromb Vasc Biol 2007;27:1788-1795.[Abstract/Free Full Text] 21. Lawson JA, Li H, Rokach J, et al. Identification of two major F2 isoprostanes 8, 12-iso-and 5-epi-8, 12-iso-isoprostane F2alpha-VI, in human urine J Biol Chem 1998;273:29295-29301.[Abstract/Free Full Text] 22. Li H, Lawson JA, Reilly M, et al. Quantitative high performance liquid chromatography/tandem mass spectrometric analysis of the four classes of F2-isoprostanes in human urine Proc Natl Acad Sci U S A 1999;96:13381-13386.[Abstract/Free Full Text] 23. Rodenburg J, Vissers MN, Wiegman A, et al. Oxidized low-density lipoprotein in children with familial hypercholesterolemia and unaffected siblings: effect of pravastatin J Am Coll Cardiol 2006;47:1803-1810.[Abstract/Free Full Text] 24. Silaste ML, Rantala M, Alfthan G, et al. Changes in dietary fat intake alter plasma levels of oxidized low-density lipoprotein and lipoprotein(a) Arterioscler Thromb Vasc Biol 2004;24:498-503.[Abstract/Free Full Text] 25. Morrow JD. Quantification of isoprostanes as indices of oxidant stress and the risk of atherosclerosis in humans Arterioscler Thromb Vasc Biol 2005;25:279-286.[Abstract/Free Full Text] 26. Lawson JA, Rokach J, FitzGerald GA. Isoprostanes: formation, analysis and use as indices of lipid peroxidation in vivo J Biol Chem 1999;274:24441-24444.[Free Full Text] 27. Patrono C, FitzGerald GA. Isoprostanes: potential markers of oxidant stress in atherothrombotic disease Arterioscler Thromb Vasc Biol 1997;17:2309-2315.[Abstract/Free Full Text] 28. Reilly MP, Pratico D, Delanty N, et al. Increased formation of distinct F2 isoprostanes in hypercholesterolemia Circulation 1998;98:2822-2828.[Abstract/Free Full Text] 29. Morrow JD, Frei V, Longmire AW, et al. Increase in circulating products of lipid peroxidation (F2-isoprostanes) in smokers. Smoking as a cause of oxidative damage. N Engl J Med 1995;332:1198-1203.[CrossRef][Web of Science][Medline] 30. Reilly M, Delanty N, Lawson JA, FitzGerald GA. Modulation of oxidant stress in vivo in chronic cigarette smokers Circulation 1996;94:19-25.[Abstract/Free Full Text] 31. Practico D, Tangirala RK, Rader DJ, Rokach J, FitzGerald GA. Vitamin E suppresses isoprostane generation in vivo and reduces atherosclerosis in ApoE-deficient mice Nat Med 1998;4:1189-1192.[CrossRef][Web of Science][Medline] 32. Griendling KK, FitzGerald GA. Oxidative stress and cardiovascular injury: Part II: animal and human studies Circulation 2003;108:2034-2040.[Free Full Text] 33. Kadiiska MB, Gladen BC, Baird DD, et al. Biomarkers of oxidative stress study II: are oxidation products of lipids, proteins, and DNA markers of CCl4 poisoning? Free Radic Biol Med 2005;38:698-710.[CrossRef][Web of Science][Medline] 34. Mehrabi MR, Ekmekcioglu C, Tatzber F, et al. The isoprostane, 8-epi-PGF2 alpha, is accumulated in coronary arteries isolated from patients with coronary heart disease Cardiovasc Res 1999;43:492-499.[CrossRef][Web of Science][Medline] 35. Practico D, Iuliano L, Mauriello A, et al. Localization of distinct F2-isoprostanes in human atherosclerotic lesions J Clin Invest 1997;100:2028-2034.[Web of Science][Medline] 36. Desideri G, Croce G, Tucci M, et al. Effects of bezafibrate and simvastatin on endothelial activation and lipid peroxidation in hypercholesterolemia: evidence of different vascular protection by different lipid-lowering treatments J Clin Endocrinol Metab 2003;88:5341-5347.[Abstract/Free Full Text] 37. Meagher EA, Barry OP, Lawson JA, Rokach J, FitzGerald GA. Effects of vitamin E on lipid peroxidation in healthy persons JAMA 2001;285:1178-1182.[Abstract/Free Full Text] 38. Holvoet P, Davey PC, De Keyzer D, et al. Oxidized low-density lipoprotein correlates positively with toll-like receptor 2 and interferon regulatory factor-1 and inversely with superoxide dismutase-1 expression: studies in hypercholesterolemic swine and THP-1 cells Arterioscler Thromb Vasc Biol 2006;26:1558-1565.[Abstract/Free Full Text] 39. Holvoet P, Harris TB, Tracy RP, et al. Association of high coronary heart disease risk status with circulating oxidized LDL in the well-functioning elderly: findings from the Health, Aging and Body Composition Study Arterioscler Thromb Vasc Biol 2003;23:1444-1448.[Abstract/Free Full Text] 40. Holvoet P, Kritchevsky SB, Tracy RP, et al. The metabolic syndrome, circulating oxidized LDL, and risk of myocardial infarction in well-functioning elderly people in the health, aging, and body composition cohort Diabetes 2004;53:1068-1073.[Abstract/Free Full Text] 41. Wu T, Willett WC, Rifai N, Shai I, Manson JE, Rimm EB. Is plasma oxidized low-density lipoprotein, measured with the widely used antibody 4E6, an independent predictor of coronary heart disease among U.S. men and women? J Am Coll Cardiol 2006;48:973-979.[Abstract/Free Full Text] 42. Tsouli SG, Kiortsis DN, Lourida ES, et al. Autoantibody titers against oxLDL are correlated with Achilles tendon thickness in patients with familial hypercholesterolemia J Lipid Res 2006;47:2208-2214.[Abstract/Free Full Text] 43. van Tits LJ, van Himbergen TM, Lemmers HL, de Graaf J, Stalenhoef AF. Proportion of oxidized LDL relative to plasma apolipoprotein B does not change during statin therapy in patients with heterozygous familial hypercholesterolemia Atherosclerosis 2006;185:307-312.[CrossRef][Medline] 44. Ndrepepa G, Braun S, von Beckerath N, et al. Oxidized low density lipoproteins, statin therapy and severity of coronary artery disease Clin Chim Acta 2005;360:178-186.[CrossRef][Web of Science][Medline] 45. Tamura A, Watanbe T, Nasu M. Effects of atorvastatin and pravastatin on malondialdehyde-modified LDL in hypercholesterolemic patients Circ J 2003;67:816-820.[CrossRef][Web of Science][Medline] 46. Sasaki S, Kuwahara N, Kunitomo K, et al. Effects of atorvastatin on oxidized low-density lipoprotein, low-density lipoprotein subfraction distribution and remnant lipoprotein in patients with mixed hyperlipoproteinemia Am J Cardiol 2002;89:386-389.[CrossRef][Web of Science][Medline] 47. Edelstein C, Pfaffinger D, Hinman J, et al. Lysine-phosphatidylcholine adducts in kringle V impart unique immunological and potential pro-inflammatory properties to human apolipoprotein(a) J Biol Chem 2003;278:52841-52847.[Abstract/Free Full Text] 48. Fraley AE, Tsimikas S. Clinical applications of circulating oxidized low-density lipoprotein biomarkers in cardiovascular disease Curr Opin Lipidol 2006;17:502-509.[Web of Science][Medline] 49. Frostegard J, Wu R, Lemne C, Thulin T, Witztum JL, de Faire U. Circulating oxidized low-density lipoprotein is increased in hypertension Clin Sci 2003;105:615-620.[CrossRef][Web of Science][Medline] 50. Tsimikas S, Brilakis ES, Miller ER, et al. Oxidized phospholipids, Lp(a) lipoprotein, and coronary artery disease N Engl J Med 2005;353:46-57.[CrossRef][Web of Science][Medline] 51. Tsimikas S, Kiechl S, Willeit J, et al. Oxidized phospholipids predict the presence and progression of carotid and femoral atherosclerosis and symptomatic cardiovascular disease: five-year prospective results from the Bruneck study J Am Coll Cardiol 2006;47:2219-2228.[Abstract/Free Full Text] 52. Tsimikas S, Aikawa M, Miller Jr. FJ, et al. Increased plasma oxidized phospholipid: apolipoprotein B-100 ratio with concomitant depletion of oxidized phospholipids from atherosclerotic lesions after dietary lipid-lowering: a potential biomarker of early atherosclerosis regression Arterioscler Thromb Vasc Biol 2007;27:175-181.[Abstract/Free Full Text] 53. Cyrus T, Praticò D, Zhao L, et al. Absence of 12/15-lipoxygenase expression decreases lipid peroxidation and atherogenesis in apolipoprotein e-deficient mice Circulation 2001;103:2277-2282.[Abstract/Free Full Text] 54. Tsimikas S, Palinski W, Witztum JL. Circulating autoantibodies to oxidized LDL correlate with arterial accumulation and depletion of oxidized LDL in LDL receptor-deficient mice Arterioscler Thromb Vasc Biol 2001;21:95-100.[Abstract/Free Full Text] 55. Orem C, Orem A, Uydu HA, Celik S, Erdol C, Kural BV. The effects of lipid-lowering therapy on low-density lipoprotein auto-antibodies: relationship with low-density lipoprotein oxidation and plasma total antioxidant status Coron Artery Dis 2002;13:65-71.[CrossRef][Web of Science][Medline] 56. Fredrikson GN, Hedblad B, Berglund G, et al. Association between IgM against an aldehyde-modified peptide in apolipoprotein B-100 and progression of carotid disease Stroke 2007;38:1495-1500.[Abstract/Free Full Text] 57. Resch U, Tatzber F, Budinsky A, Sinzinger H. Reduction of oxidative stress and modulation of autoantibodies against modified low-density lipoprotein after rosuvastatin therapy Br J Clin Pharmacol 2006;61:262-274.[CrossRef][Web of Science][Medline] 58. Macphee CH. Lipoprotein-associated phospholipase A2: a potential new risk factor for coronary artery disease and a therapeutic target Curr Opin Pharmacol 2001;1:121-125.[CrossRef][Medline] 59. Ballantyne CM, Hoogeveen RC, Bang H, et al. Lipoprotein-associated phospholipase A2 high sensitivity C-reactive protein, and risk for incident coronary heart disease in middle-aged men and women in the Atherosclerosis Risk in Communities (ARIC) study Circulation 2004;109:837-842.[Abstract/Free Full Text] 60. Packard CJ, O'Reilly DS, Caslake MJ, et al. Lipoprotein-associated phospholipase A2 as an independent predictor of coronary heart disease. West of Scotland Coronary Prevention Study Group. N Eng J Med 2000;343:1148-1155.[CrossRef][Web of Science][Medline] 61. Schaefer EJ, McNamara JR, Asztalos BF, et al. Effects of atorvastatin versus other statins on fasting and postprandial C-reactive protein and lipoprotein-associated phospholipase A2 in patients with coronary heart disease versus control subjects Am J Cardiol 2005;95:1025-1032.[CrossRef][Web of Science][Medline] 62. Albert MA, Glynn RJ, Wolfert RL, Ridker PM. The effect of statin therapy on lipoprotein associated phospholipase A2 levels Atherosclerosis 2005;182:193-198.[Web of Science][Medline] 63. Tsimikas S, Tsironis LD, Tselepis AD. New insights into the role of lipoprotein(a)-associated lipoprotein-associated phospholipase A2 in atherosclerosis and cardiovascular disease Arterioscler Thromb Vasc Biol 2007;10:2094-2099.
This article has been cited by other articles:
|
|
|
|
 
N. S. Rajendra, S. Ireland, J. George, J. J. F. Belch, C. C. Lang, and A. D. Struthers
Mechanistic Insights Into the Therapeutic Use of High-Dose Allopurinol in Angina Pectoris
J. Am. Coll. Cardiol.,
August 16, 2011;
58(8):
820 - 828.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
N. Faghihnia, S. Tsimikas, E. R. Miller, J. L. Witztum, and R. M. Krauss
Changes in lipoprotein(a), oxidized phospholipids, and LDL subclasses with a low-fat high-carbohydrate diet
J. Lipid Res.,
November 1, 2010;
51(11):
3324 - 3330.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
Dayangku Fatiha Pengiran Burut, Y. Karim, and G. A. A. Ferns
The Role of Immune Complexes in Atherogenesis
Angiology,
October 1, 2010;
61(7):
679 - 689.
[Abstract]
[PDF]
|
|
|
|
|
|
|
S. Tsimikas, Z. Mallat, P. J. Talmud, J. J. P. Kastelein, N. J. Wareham, M. S. Sandhu, E. R. Miller, J. Benessiano, A. Tedgui, J. L. Witztum, et al.
Oxidation-Specific Biomarkers, Lipoprotein(a), and Risk of Fatal and Nonfatal Coronary Events
J. Am. Coll. Cardiol.,
September 14, 2010;
56(12):
946 - 955.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
Z.-h. Wang, X.-l. Liu, M. Zhong, L.-p. Zhang, Y.-y. Shang, X.-y. Hu, L. Li, Y. Zhang, J.-t. Deng, and W. Zhang
Pleiotropic Effects of Atorvastatin on Monocytes in Atherosclerotic Patients
J. Clin. Pharmacol.,
March 1, 2010;
50(3):
311 - 319.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
A. E. Fraley, G. G. Schwartz, A. G. Olsson, S. Kinlay, M. Szarek, N. Rifai, P. Libby, P. Ganz, J. L. Witztum, S. Tsimikas, et al.
Relationship of Oxidized Phospholipids and Biomarkers of Oxidized Low-Density Lipoprotein With Cardiovascular Risk Factors, Inflammatory Biomarkers, and Effect of Statin Therapy in Patients With Acute Coronary Syndromes: Results From the MIRACL (Myocardial Ischemia Reduction With Aggressive Cholesterol Lowering) Trial
J. Am. Coll. Cardiol.,
June 9, 2009;
53(23):
2186 - 2196.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
M. H. SHISHEHBOR and S. L. HAZEN
JUPITER to Earth: A statin helps people with normal LDL-C and high hs-CRP, but what does it mean?
Cleveland Clinic Journal of Medicine,
January 1, 2009;
76(1):
37 - 44.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
Top
Abstract
Methods
