Journal of the American College of Nutrition, Vol. 25, No. 5, 420-428 (2006)
Published by the American College of Nutrition
Alpha-Tocopherol Distribution in Lipoproteins and Anti-Inflammatory Effects Differ between CHD-Patients and Healthy Subjects
Alexander Leichtle, MD,
Daniel Teupser, MD, PhD and
Joachim Thiery, MD, PhD
Institute of Laboratory Medicine, Clinical Chemistry, and Molecular Diagnostics, Leipzig University Hospital, Leipzig, GERMANY
Address reprint requests to: Daniel Teupser M.D., Ph.D., Institute of Laboratory Medicine, Clinical Chemistry, and Molecular Diagnostics, Leipzig University Hospital, Liebigstrasse 27, 04103 Leipzig, GERMANY. E-mail: teupser{at}medizin.uni-leipzig.de
 |
ABSTRACT
|
|---|
Objective: The purpose of this study was to investigate the dose-dependent effects of RRR-
-tocopherol supplementation in coronary heart disease (CHD) patients and healthy subjects on plasma -tocopherol levels, plasma lipoprotein distribution, LDL oxidation, and inflammatory plasma markers.
Methods: 12 patients with coronary heart disease and 12 healthy subjects were supplemented with increasing dosages of RRR--tocopherol at 100, 200 and 400 mg/day for a period of 3 weeks per dose. Lipoproteins were separated by FPLC and ultracentrifugation. -Tocopherol was measured by HPLC. Resistance of LDL to oxidation was determined by reading the absorption at 234 nm after CuCl2-induced oxidation. Clinical chemistry and inflammatory markers were measured on automated analysis systems.
Results: Plasma -tocopherol concentrations at baseline were comparable between CHD-patients and healthy subjects (21.7 ± 4.7 µmol/L and 25.8 ± 7.6 µmol/L, respectively). CHD-patients showed a significant increase (59%) of plasma -tocopherol concentrations to 34.6 ± 9.8 µmol/L at a dosage of 100 mg/day RRR--tocopherol, whereas healthy subjects showed a significant (54%) increase to 39.7 ± 6.1 µmol/L only with 400 mg/day RRR--tocopherol. In addition, CHD-patients showed a significantly increased enrichment of -tocopherol in VLDL. Supplementation (200 mg/day) caused a significant decrease of the acute phase plasma proteins C-reactive protein (CRP) (–65%) and fibrinogen (–24%).
Conclusion: Our data demonstrate that CHD-patients require lower dosages of -tocopherol supplementation than healthy subjects to exert biological effects on plasma lipoproteins and acute phase response.
Key words: coronary heart disease, alpha-tocopherol, vitamin E, C-reactive protein, fibrinogen
|
INTRODUCTION
|
|---|
The concept of beneficial effects of the lipid-soluble antioxidant -tocopherol in the development of atherosclerosis is tightly linked with the hypothesis that oxidation of LDL plays a critical role in atherogenesis. Oxidatively modified LDL can be taken up by scavenger receptors expressed on macrophages, leading to cholesterol uptake and subsequent foam cell formation [1,2]. -Tocopherol is capable of reducing oxidative modification of LDL and may thus decrease cholesterol accumulation in macrophages. In vitro experiments have convincingly shown that the resistance to oxidation was increased when LDL were loaded with -tocopherol [3]. In addition, we and others have shown that -tocopherol down-regulates scavenger receptor activity in macrophages by mechanisms independent of the anti-oxidant properties of -tocopherol [4,5]. Other vascular effects of -tocopherol include inhibition of smooth muscle cell proliferation, platelet aggregation and monocyte adhesion [6]. Although data from animal models clearly support anti-atherogenic properties of -tocopherol [7–9], recent clinical intervention trials have failed to provide evidence for beneficial effects of -tocopherol supplementation in primary and secondary prevention of coronary heart disease [10,11]. Jialal and Devaraj summarized factors, possibly accounting for the lack of benefit in the majority of trials, including missing assessment of compliance, measurement of antioxidant levels, biomarkers of oxidative stress and administration of different forms and dosages of vitamin E [12]. In addition, it is not clear to what extent the inconsistent results of -tocopherol supplementation in the prevention of cardiovascular disease might be related to a possibly altered uptake and distribution of -tocopherol in lipoproteins of CHD-patients compared to healthy subjects. To the best of our knowledge, there is no data comparing the effect of -tocopherol supplementation in CHD-patients and healthy individuals. Since lipoproteins are the main carrier of -tocopherol [13], slightly changed uptake patterns in lipoprotein classes could lead to major changes in overall -tocopherol effectiveness.
Therefore, the aim of this study was to compare the effect of -tocopherol supplementation on plasma -tocopherol levels and distribution, antioxidant properties, and inflammatory markers in CHD patients and healthy subjects.
|
MATERIALS AND METHODS
|
|---|
Study Population
We studied 12 outpatients (9 male/3 female) with angiographically assessed coronary heart disease (CHD) and 12 healthy subjects (6 male/6 female). Patients were recruited at the Clinic of Internal Medicine I, University Hospital Munich; healthy subjects were recruited from the hospital staff. The study was approved by the ethics committee of the University of Munich. All participants gave their informed consent. Inclusion criteria for both groups were plasma cholesterol concentrations <6.5 mmol/L and plasma triglyceride concentrations <2.9 mmol/L, no invasive intervention within 6 months prior to enrollment, no malignant, acute or chronic disease or renal disease, no diabetes mellitus and no vitamin supplementation within one month prior to enrollment. An additional inclusion criterion for the patient group was proven cardiovascular disease, which was an exclusion criterion for the control group.
Study Design
The study comprised a total of four visits, one visit at baseline (visit 1) followed by visits every three weeks for a period of 9 weeks (visits 2, 3, and 4). In all subjects and at all visits, a careful medical history was queried and a thorough medical examination including measurement of height, weight, blood pressure, and pulse frequency was performed. During the course of the study, participants were supplemented with increasing dosages of RRR--tocopherol, starting at 100 mg/day for three weeks, 200 mg/day for the following three weeks and 400 mg/day for the last three weeks. Blood was drawn at the end of each supplementation period. Capsules containing RRR--tocopherol at dosages of 100 mg, 200 mg, and 400 mg used as study medication were a kind gift of Bayer Vital GmbH & Co KG, Germany. Unused capsules were collected after each supplementation period to determine subject compliance.
Clinical Chemistry
Alanine aminotransferase (ALAT), aspartate aminotransferase (ASAT), gamma-glutamyl transferase (GGT), alkaline phosphatase (AP), creatine kinase (CK), total protein, cholesterol, triglycerides, apolipoprotein B (apoB), apolipoprotein A1 (apoA1), glucose, creatinine, urea and uric acid were determined on an automated Hitachi 917 analyzer (Roche, Germany) according to the German "RiliBÄK" guidelines [14].
Inflammatory Markers
Fibrinogen was determined immunologically with a nephelometric assay on a Behring nephelometer (BN II, Behring, Germany) from 300 µL EDTA plasma frozen at –20°C immediately after sampling. C-reactive Protein (CRP) was determined on a COBAS Integra 400 system (Roche, Germany). ‘High-sensitivity’ testing was performed with an immunotubidimetric method in EDTA plasma frozen at –20°C immediately after sampling.
Fast Pressure Liquid Chromatography (FPLC)
Cholesterol and -tocopherol distribution among lipoproteins were determined by fast pressure liquid chromatography (Amersham Pharmacia, Germany). Plasma samples (100 µL) were loaded on a superose 6 column, eluted with 0.15 mol/L NaCl, 0.01 mol/L Na2HPO4, 0.1 mmol/L EDTA, pH 7.5 at a constant flow rate of 0.5 mL/min, and collected in 0.5 mL fractions. Cholesterol in the fractions was determined enzymatically on micro titer plates using 100 µL standard/sample and 150 µL reagent (Roche, Germany) with standards ranging from 0 to 0.26 mmol/L (0 to 10 mg/dL). -tocopherol and 
-tocopherol were determined as described below. FPLC profiles were done for each individual patient at visit 1 and visit 3 and from plasma pools of all CHD-patients and all healthy subjects at visits 2 and 4. Mean recovery of -tocopherol and cholesterol in FPLC fractions compared to direct measurement exceeded 79% and values obtained from FPLC fractions were normalized to the values obtained by direct measurement. Fractions 14–18 were designated VLDL, fractions 19–26 LDL and fractions 27–38 HDL.
-Tocopherol and -Tocopherol Determination
-Tocopherol and -tocopherol in plasma and FPLC samples were determined by high pressure liquid chromatography (HPLC) using a method adapted from Jansson [15] and Lehmann [16]. 100 µL plasma or FPLC sample were mixed with 100 µL 
-tocopherol internal standard (ethanolic solution of 1 g/L butylhydroxytoluol and 100 mg/L -tocopherol (Sigma) in a 1:100 dilution) and 400 µL n-hexane, vortexed and centrifuged (1000 g, 1 min). 200 µL of the supernatant were transferred to 1.5 mL tubes and evaporated in a vacuum centrifuge. Residua were dissolved in 100 µL methanol. Tocopherol measurements were performed on a Merck Hitachi (Merck, Germany) system using degassed methanol as mobile phase. 10 µL sample volume was injected in a 4 x 4 mm 5 µm LiChrospher 100 RP 18 guard column and a 250 x 4 mm 5 µm LiChrospher 100 RP 18 column (Merck, Germany) and separated isocratically for 12 min. at 20°C. For fluorescence detection, an excitation wavelength of 295 nm and an emission wavelength of 330 nm were used. Specific peaks for -, -, and -tocopherol were quantified by automated computing of the area under curve. Recovery rates for - and -tocopherol were computed via the internal standard recovery.
Ascorbate (Vitamin C) Determination
Ascorbate in plasma samples was determined according to the method described by Halevy [17] in adaption of the method published by Albanese [18]. 500 µL EDTA plasma were deproteinated by addition of 500 µL trichloric acid (10%) and subsequent vortexing and centrifugation. The supernatant was stored at –20°C until analysis. A reaction solution consisting of 10 mL dinitrophenylhydrazine (DNPH, 22 g/L in 10N H2SO4), 1 mL thiourea (50 g/L in H2O) and 1 mL CuSO4 solution (6 g/L CuSO4*5 H2O in H2O) was prepared. 100 µL sample and 50 µL reaction solution were mixed on microtiter plates and incubated for 3 h under continuous agitation. After addition of 150 µL H2SO4 (65%) per well and 15 min of incubation, the extinction was measured at a wavelength of 520 nm and a reference wavelength of 630 nm. The ascorbate concentrations were computed by linear regression using ascorbate standard preparations.
Determination of LDL Oxidation Resistance
The resistance of LDL to oxidation was determined as previously described [17]. Briefly, LDL was isolated from 1 ml EDTA-plasma by sequential ultracentrifugation and subjected to CuCl2 induced oxidation. The formation of conjugated diënes was followed by monitoring the absorbance at 234 nm. The lag phase (in minutes) was determined as the intercept of the baseline and the slope of the absorbance curve in the propagation phase.
IL-6 and Tumor Necrosis Factor (TNF ) Measurement
IL-6 and TNF were determined using a Bio-Plex cytokine assay on a Bio-Plex suspension array system according to the instructions of the manufacturer (BioRad, Germany). 50 µL frozen (–20°C) serum samples were thawed on ice and analyzed directly without dilution.
Statistical Analysis
Statistical data analysis was performed using SPSS for Windows (SPSS, USA). Normality of distribution was tested with the Kolmogorov-Smirnov test. Nonparametric Mann-Whitney-U testing was applied for between study group comparisons and Student’s paired samples t-testing was used where appropriate. P values less than 0.05 were considered significant. Quantitative data are expressed as mean ± standard deviation, unless otherwise noted.
|
RESULTS
|
|---|
The baseline demographic and clinical characteristics of the two study groups are listed in Table 1. CHD-patients had significantly higher plasma triglyceride levels and VLDL-cholesterol than healthy subjects but did not differ in any of the other lipid parameters. CHD-patients also showed significantly increased plasma fibrinogen levels when compared to healthy subjects. Since healthy subjects were hospital employees and age matching was not performed, CHD-patients were significantly older and showed an increased body-mass index.
Both study groups were supplemented with RRR--tocopherol at 100 mg/day, 200 mg/day, and 400 mg/day for a three week period per dosage level. The dosage was increased to the next level at the end of each period. At baseline, plasma -tocopherol was comparable between CHD-patients and healthy subjects (21.7 ± 4.7 µmol/L and 25.8 ± 7.6 µmol/L, respectively, Table 2). Plasma -tocopherol concentrations increased significantly during supplementation. However, there was a marked difference between patients and healthy subjects in their response of plasma -tocopherol to supplementation. While CHD-patients showed a significant 59% increase of plasma -tocopherol levels to 34.6 ± 9.8 µmol/L already after supplementation with 100 mg/d RRR--tocopherol, healthy subjects showed a significant 54% increase to 39.7 ± 6.1 µmol/L only at the end of the study after supplementation with 400 mg/d RRR--tocopherol (Table 2). In CHD-patients, -tocopherol concentrations further increased towards the end of the study up to a maximum of 42.8 ± 9.0 µmol/L (2.0-fold compared to baseline). For -tocopherol, we observed a plasma concentration pattern that was inverse to that of -tocopherol. At baseline levels were not different between CHD-patients and healthy subjects. During supplementation, CHD-patients showed a significant decrease (45%) of plasma -tocopherol already after 3 weeks with 100 mg/d RRR--tocopherol, whereas healthy subjects showed a significant decrease (50%) only at the end of the study (Table 2). We also determined the plasma concentration of ascorbate as a water-soluble antioxidant but did not find any baseline differences or changes during the supplementation with -tocopherol (Table 2).
View this table:
[in this window]
[in a new window]
|
Table 2. Lipid Profile, -Tocopherol Distribution among Lipoproteins and other Antioxidants during -Tocopherol Supplementation
|
|
Supplementation had no significant influence on plasma total cholesterol or on triglycerides. In addition, no change in the distribution of lipoprotein fractions was found in CHD-patients. However, a significant increase of VLDL cholesterol and comparable decrease in LDL cholesterol was observed in the healthy subjects (Table 2).
We next determined the distribution of -tocopherol in the lipoprotein fractions by FPLC. Fig. 1 shows that -tocopherol was closely associated with VLDL, LDL and HDL. We next calculated the concentrations of -tocopherol in VLDL, LDL and HDL and found a uniform relative increase of -tocopherol concentrations in all three lipoprotein classes (Fig. 2 A, B). This was further substantiated by calculating the relative distribution of -tocopherol in VLDL, LDL and HDL (Fig. 2 C, D) which remained constant during supplementation. Fig. 2 C, D also shows a dramatic difference in the distribution of -tocopherol between CHD-patients and healthy subjects. The distribution of -tocopherol in VLDL, LDL and HDL at baseline was 8%, 38% and 54% in healthy subjects and 23%, 43% and 34% in patients (Fig. 2C, D). This difference originated from a significantly higher association of -tocopherol with VLDL and a significantly lower association of -tocopherol with HDL. Assuming a molar content of cholesterol in VLDL, LDL and HDL of 7139, 1785 and 45 mol/mol lipoprotein, respectively [19], we determined the number of -tocopherol molecules per molecule lipoprotein. Fig. 3 shows that supplementation with -tocopherol led to a dramatic increase in the number of -tocopherol molecules in VLDL in CHD patients (visit 1: 61 ± 24 mol/mol; visit 3: 112 ± 35 mol/mol, p < 0.01) whereas no change was observed in healthy subjects (visit 1: 51 ± 30 mol/mol; visit 3: 66 ± 14, p = n.s.). A significant increase in the number of -tocopherol molecules was also found in LDL, which was more pronounced in patients than healthy subjects (visit 3: patients 11.6 ± 1.9 mol/mol; healthy subjects 9.8 ± 2.3, p < 0.05). This may also reflect the significantly increased oxidation resistance of LDL isolated from CHD-patients compared to healthy subjects (Table 3). In contrast to VLDL and LDL, which at baseline carried comparable numbers of -tocopherol molecules per particle, the baseline -tocopherol load of HDL was significantly higher in healthy subjects compared to CHD-patients (0.36 ± 0.06 mol/mol vs. 0.25 ± 0.08, respectively, p < 0.01, Fig. 3). The increase of -tocopherol molecules in HDL particles during supplementation was more pronounced in patients than in healthy subjects and thus only reached significance in patients (72% increase at visit 3, p < 0.01, Fig. 3). Since previous studies have shown anti-inflammatory effects of -tocopherol [20,21], we next determined plasma levels of the acute phase proteins CRP and fibrinogen. Table 3 shows that CHD-patients had elevated CRP and fibrinogen concentrations. Supplementation with -tocopherol led to a decrease in CRP in CHD-patients, which was only significant at visit 3 (p < 0.05). Since CRP is induced by the release of IL-6 [20,22], we also determined plasma IL-6 concentrations and confirmed a significant decrease at visit 3 (p = 0.05). However, -tocopherol supplementation had no significant effect on TNF concentrations (data not shown). A more prominent effect was observed for fibrinogen levels which were reduced in patients after supplementation with -tocopherol and reached comparable levels as in the control group (Table 3).
View larger version (82K):
[in this window]
[in a new window]
|
Fig. 2. Absolute and relative -tocopherol content in VLDL, LDL and HDL in controls (A, C) and CHD-patients (B, D).
|
|
|
DISCUSSION
|
|---|
This study shows dramatic differences between CHD-patients and normal subjects in their response to -tocopherol supplementation. Loading of plasma lipoproteins with -tocopherol could be achieved more readily in CHD-patients than in healthy subjects. Evidence is that in CHD-patients plasma levels of total -tocopherol increased significantly already at 100 mg/day, while in healthy subjects, this increase was only seen at the highest dose of 400 mg/day (Fig. 2 A, B). At 200 mg/day, a significant increase of -tocopherol content per lipoprotein particle was found in VLDL, LDL and HDL while in healthy subjects a significant increase was only observed in LDL (Fig. 3). To the best of our knowledge, a direct comparison of the effects of -tocopherol supplementation between CHD-patients and healthy subjects has not been described yet. In a study of normocholesterolemic adults [23], adult non-smokers [24] and in the heart protection study [25], -tocopherol plasma levels of non-supplemented subjects were 19.4, 27.2 and 27.0 µmol/L, respectively. In these studies, supplementation with -tocopherol at 600 mg, 400 IU and 600 mg/day resulted in plasma -tocopherol levels of 38.0, 38.5 and 49.5 µmol/L, respectively. Plasma -tocopherol levels at baseline and after supplementation (400 mg/day) in our study were comparable to the published data. However, the major differences between CHD-patients and healthy subjects in our study were observed at lower dosages of 100 mg and 200 mg/day. These dosages were not used in the aforementioned studies. Perugini et al [26] suggested that at least a daily regimen of 400 IU or higher would be required in order to get a statistically significant increase in -tocopherol content in plasma and LDL. Here we could show that with respect to total plasma -tocopherol concentrations, this statement is true only for healthy subjects but not for the CHD-patients which showed a significant increase even at the lowest dose of supplementation (100 mg/d). Thus, one could speculate that CHD-patients may require significantly lower dosages of -tocopherol supplementation and dosages which may be adequate for healthy subjects may be capable of exerting adverse effects [27]. Although -tocopherol is considered relatively safe compared to other fat-soluble vitamins [28], Miller et al concluded in a recent meta-analysis of 19 clinical trials that high-dosage vitamin E supplements (
400 IU/d) may increase all-cause mortality [10]. One explanation for the increased sensitivity of CHD-patients to -tocopherol supplementation may be that VLDL production, the main source of -tocopherol, is elevated in CHD-patients. Elevated VLDL production may not be apparent in terms of elevated plasma cholesterol concentrations, since the majority of patients were treated with statins.
Another new insight of our study was the identification of differences between the -tocopherol distribution in the lipoprotein fractions of CHD-patients and healthy subjects. In CHD-patients, the relative distribution of -tocopherol associated with VLDL, LDL, and HDL at baseline was 22%, 43%, and 34% in CHD patients and 8%, 38% and 54% in healthy subjects. Thus, in CHD patients significantly more -tocopherol was found in the VLDL fraction and significantly less in the HDL fraction. Data from previous studies show a wide range of distribution patterns in apparently healthy individuals. The relative distribution of -tocopherol associated with VLDL, LDL, and HDL reported by Behrens was 5%, 50%, and 44% [13]. Ogihara et al reported a distribution of 12%, 43% and 45% [29], Perugini et al reported 21%, 42% and 37% [26]. Data described in the latter study are quite similar to the values of CHD-patients in our study, though they were apparently obtained from healthy individuals. The study by Perugini et al. also included a supplementation with DL--tocopheryl-acetate (600 mg/day) resulting in an increase of -tocopherol associated with VLDL to 34% and a decrease of -tocopherol associated LDL and HDL to 36% and 30%, respectively. This is in contrast to our results and other studies [30,31], showing that the relative distribution of -tocopherol in the fractions remained unchanged during supplementation (Fig. 2 C, D). Though -tocopherol is secreted with VLDL by the liver [32], the transfer of -tocopherol to LDL and HDL appears to be a rapid process occurring within a few hours [30]. This supports the validity of our results for the relative distribution of -tocopherol in the lipoprotein fractions during supplementation with D--tocopherol. It also strengthens the hypothesis that increased VLDL production may be responsible for the greater sensitivity of CHD-patients to -tocopherol supplementation.
The molar ratio of molecules -tocopherol per lipoprotein particle has been investigated in few previous studies. Here, we show that in CHD-patients supplemented with 200 mg/day, the -tocopherol content per particle in all fractions increased by approximately 80%, whereas this increase was much lower in healthy subjects and reached significance only for LDL (Fig. 3). Our data at baseline confirm results from nonsupplemented subjects suggesting an average -tocopherol content of 60–70 molecules per VLDL particle [30]. During supplementation (200 mg/day) the number of -tocopherol molecules per VLDL particle increased up to 115 in CHD-patients. It is of interest that during transformation to LDL much of the -tocopherol load is lost and LDL contained only 6–7 molecules at baseline and 9–12 in the supplemented state. This corresponds to data in the literature, reporting molar ratios of -tocopherol per LDL of 7.3 [33] and 8.5 [34]. A significant difference in the particle load between CHD-patients and healthy subjects was found for HDL. While in CHD-patients, on average only every fourth HDL-particle contained one -tocopherol molecule, in healthy subjects every third HDL-particle contained -tocopherol. During supplementation the -tocopherol load of HDL increased significantly in CHD-patients resulting in an -tocopherol molecule every second to third HDL particle. One caveat with these calculations is that the lipoprotein composition may be different between CHD-patients and healthy subjects, which have not been investigated in detail in this study. The particle composition was assumed as described [19] and all calculations of -tocopherol were based on cholesterol concentrations. However, since many other studies indicate that the lipid composition of lipoproteins during -tocopherol supplementation remains unchanged [26], it should be valid to assess the relative changes in the lipoproteins.
An unexpected finding was an increase of VLDL-cholesterol in healthy subjects after supplementation with -tocopherol and a concomitant decrease of LDL-cholesterol. This observation is delicate to interpret, since it was not seen in our CHD patient group and other studies in healthy subjects did not report changes in VLDL-cholesterol upon supplementation with -tocopherol [23].
Today, there is increasing evidence pointing to an important role for inflammation in atherogenesis [35]. We thus determined the plasma levels of the acute phase proteins CRP and fibrinogen. Baseline CRP and fibrinogen were elevated in CHD-patients compared to healthy subjects, however only the difference in fibrinogen levels reached statistical significance. In a recent meta-analysis of associations of inflammatory markers with risk of CHD in long-term prospective studies, fibrinogen ranged top (odds ratio 1.8) before CRP (odds ratio 1.5) [36]. Supplementation with -tocopherol significantly reduced fibrinogen levels in CHD-patients but not in healthy subjects, and 100 mg/day were sufficient to exert the full effect (Table 3). In addition, CRP-levels were reduced in CHD patients after supplementation with -tocopherol, though this effect was significant only at 200 mg/day. The concomitant significant reduction of IL-6 suggests that the CRP-reduction is mediated by the reduction of IL-6. These data corroborate our data on plasma -tocopherol levels, showing that low dosages of supplementation in CHD patients do not only significantly increase plasma -tocopherol, but also exert biological functions. It must be noted, however that in another study in diabetic subjects, a significant reduction of CRP was found using 1200 IU -tocopherol, though no data were reported on fibrinogen concentrations and other dosages of -tocopherol [20].
|
CONCLUSION
|
|---|
Our data show that CHD-patients require much lower dosages of -tocopherol supplementation than healthy subjects to exert a significant increase of -tocopherol plasma levels and to reduce the acute phase proteins fibrinogen and CRP. We speculate that the increased sensitivity to -tocopherol supplementation may relate to an increased lipoprotein synthesis which is the primary carrier of -tocopherol in the circulation.
|
ACKNOWLEDGMENTS
|
|---|
We thank Ulrike Haas, Wolfgang Wilfert, Julian Jöris and Martin Nerlich for expert technical assistance. We thank Dr. Wolfgang von Scheidt for recruiting the CHD-patients.
|
FOOTNOTES
|
|---|
This study was supported by a grant from Bayer Vital GmbH & Co KG, Germany.
Received August 31, 2005.
Accepted February 6, 2006.
|
REFERENCES
|
|---|
- Steinberg D, Parthasarathy S, Carew TE, Khoo JC, Witztum JL: Beyond cholesterol. Modifications of low-density lipoprotein that increase its atherogenicity.N Engl J Med320
:915
–924,1989
.[Medline]
- Henriksen T, Mahoney EM, Steinberg D: Enhanced macrophage degradation of low density lipoprotein previously incubated with cultured endothelial cells: recognition by receptors for acetylated low density lipoproteins.Proc Natl Acad Sci USA78
:6499
–6503,1981
.[Abstract/Free Full Text]
- Dieber-Rotheneder M, Puhl H, Waeg G, Striegl G, Esterbauer H: Effect of oral supplementation with D-alpha-tocopherol on the vitamin E content of human low density lipoproteins and resistance to oxidation.J Lipid Res32
:1325
–1332,1991
.[Abstract]
- Teupser D, Thiery J, Seidel D: Alpha-tocopherol down-regulates scavenger receptor activity in macrophages.Atherosclerosis144
:109
–115,1999
.[Medline]
- Devaraj S, Hugou I, Jialal I: Alpha-tocopherol decreases CD36 expression in human monocyte-derived macrophages.J Lipid Res42
:521
–527,2001
.[Abstract/Free Full Text]
- Devaraj S, Jialal I: The effects of alpha-tocopherol on critical cells in atherogenesis.Curr Opin Lipidol9
:11
–15,1998
.[Medline]
- Verlangieri AJ, Bush MJ: Effects of d-alpha-tocopherol supplementation on experimentally induced primate atherosclerosis.J Am Coll Nutr11
:131
–138,1992
.[Abstract]
- Schwenke DC, Rudel LL, Sorci-Thomas MG, Thomas MJ: Alpha-tocopherol protects against diet induced atherosclerosis in New Zealand white rabbits.J Lipid Res43
:1927
–1938,2002
.[Abstract/Free Full Text]
- Peluzio MC, Homem AP, Cesar GC, Azevedo GS, Amorim R, Cara DC, Saliba H, Vieira EC, Arantes RE, Alvarez-Leite J: Influences of alpha-tocopherol on cholesterol metabolism and fatty streak development in apolipoprotein E-deficient mice fed an atherogenic diet.Braz J Med Biol Res34
:1539
–1545,2001
.[Medline]
- Miller ER, Pastor-Barriuso R, Dalal D, Riemersma RA, Appel LJ, Guallar E: Meta-Analysis: High-dosage vitamin E supplementation may increase all-cause mortality.Ann Intern Med142
:37
–46,2004
.
- Munteanu A, Zingg JM, Azzi A: Anti-atherosclerotic effects of vitamin E—myth or reality?J Cell Mol Med8
:59
–76,2004
.[Medline]
- Jialal I, Devaraj S: Scientific evidence to support a vitamin E and heart disease health claim: research needs.J Nutr135
:348
–353,2005
.[Abstract/Free Full Text]
- Behrens WA, Thompson JN, Madere R: Distribution of alpha-tocopherol in human plasma lipoproteins.Am J Clin Nutr35
:691
–696,1982
.[Abstract/Free Full Text]
- Richtlinie der Bundesärztekammer zur Qualitätssicherung quantitativer laboratoriumsmedizinischer Untersuchungen.Deutsches Ärzteblatt98
, Heft 42
- Jansson L, Nilsson B, Lindgren R: Quantitation of serum tocopherols by high-performance liquid chromatography with fluorescence detection.J Chromatogr181
:242
–247,1980
.[Medline]
- Lehmann J, Martin H: Improved direct determination of alpha- and gamma-tocopherol in plasma and platelets by liquid chromatography with fluorescence detection.Clin Chem28
:1784
–1787,1982
.[Abstract/Free Full Text]
- Halevy D, Thiery J, Nagel D, Arnold S, Erdmann E, Hofling B, Cremer P, Seidel D: Increased oxidation of LDL in patients with coronary artery disease is independent from dietary vitamins E and C.Arterioscler Thromb Vasc Biol17
:1432
–1437,1997
.[Abstract/Free Full Text]
- Albanese AA, Wein EH, Mata LA: An improved method for determination of leucocyte and plasma ascorbic acid of man with applications to studies on nutritional needs and effects of cigarette smoking.Nutr Rep Int12
:271
–289,1975
.
- Shen BW, Scanu AM, Kezdy FJ: Structure of human serum lipoproteins inferred from compositional analysis.Proc Natl Acad Sci USA74
:837
–841,1977
.[Abstract/Free Full Text]
- Devaraj S, Jialal I: Alpha tocopherol supplementation decreases serum C-reactive protein and monocyte interleukin-6 levels in normal volunteers and type 2 diabetic patients.Free Radic Biol Med29
:790
–792,2000
.[Medline]
- Devaraj S, Li D, Jialal I: The effects of alpha tocopherol supplementation on monocyte function. Decreased lipid oxidation, interleukin 1 beta secretion, and monocyte adhesion to endothelium.J Clin Invest98
:756
–763,1996
.[Medline]
- Mortensen RF: C-reactive protein, inflammation, and innate immunity.Immunol Res24
:163
–176,2001
.[Medline]
- Perugini C, Bagnati M, Cau C, Bordone R, Zoppis E, Paffoni P, Re R, Albano E, Bellomo G: Distribution of lipid-soluble antioxidants in lipoproteins from healthy subjects. I. Correlation with plasma antioxidant levels and composition of lipoproteins.Pharmacol Res41
:55
–65,2000
.[Medline]
- Huang HY, Appel LJ: Supplementation of diets with alpha-tocopherol reduces serum concentrations of gamma- and delta-tocopherol in humans.J Nutr133
:3137
–3140,2003
.[Abstract/Free Full Text]
- MRC/BHF-Study-Group MRC/BHF Heart Protection Study of antioxidant vitamin supplementation in 20,536 high-risk individuals: a randomised placebo-controlled trial.Lancet360
:23
–33,2002
.[Medline]
- Perugini C, Bagnati M, Cau C, Bordone R, Paffoni P, Re R, Zoppis E, Albano E, Bellomo G: Distribution of lipid-soluble antioxidants in lipoproteins from healthy subjects. II. Effects of in vivo supplementation with alpha-tocopherol.Pharmacol Res41
:67
–74,2000
.[Medline]
- Upston JM, Kritharides L, Stocker R: The role of vitamin E in atherosclerosis.Prog Lipid Res42
:405
–422,2003
.[Medline]
- Bendich A, Machlin LJ: Safety of oral intake of vitamin E.Am J Clin Nutr48
:612
–619,1988
.[Abstract/Free Full Text]
- Ogihara T, Miki M, Kitagawa M, Mino M: Distribution of tocopherol among human plasma lipoproteins.Clin Chim Acta174
:299
–305,1988
.[Medline]
- Parks EJ, Dare D, Frazier KB, Hellerstein MK, Neese RA, Hughes E, Traber MG: Dependence of plasma alpha-tocopherol flux on very low-density triglyceride clearance in humans.Free Radic Biol Med29
:1151
–1159,2000
.[Medline]
- Romanchik JE, Morel DW, Harrison EH: Distributions of carotenoids and alpha-tocopherol among lipoproteins do not change when human plasma is incubated in vitro.J Nutr125
:2610
–2617,1995
.[Abstract/Free Full Text]
- Kayden HJ, Traber MG: Absorption, lipoprotein transport, and regulation of plasma concentrations of vitamin E in humans.J Lipid Res34
:343
–358,1993
.[Medline]
- Ziouzenkova O, Winklhofer-Roob BM, Puhl H, Roob JM, Esterbauer H: Lack of correlation between the alpha-tocopherol content of plasma and LDL, but high correlations for gamma-tocopherol and carotenoids.J Lipid Res37
:1936
–1946,1996
.[Abstract]
- Frei B, Gaziano JM: Content of antioxidants, preformed lipid hydroperoxides, and cholesterol as predictors of the susceptibility of human LDL to metal ion-dependent and -independent oxidation.J Lipid Res34
:2135
–2145,1993
.[Abstract]
- Ross R: Atherosclerosis—an inflammatory disease.N Engl J Med340
:115
–126,1999
.[Free Full Text]
- Lowe GD: Circulating inflammatory markers and risks of cardiovascular and noncardiovascular disease.J Thromb Haemost3
:1618
–1627,2005
.[Medline]
TOP
ABSTRACT
INTRODUCTION
