The beneficial effects of virgin olive oil against oxidative stress induced by hypercholesterolemia in rats

Cardiovascular disease(CVD) remains the major cause of mortality in the world, typically claiming a third of all deaths. The primary cause of CVD is atherosclerosis. Therefore, timely prevention and therapy of atherosclerosis are able to reduce the risk of the development of its clinical manifestations. Anti-atherosclerotic activity of medicinal plants mainly appears in their multiple effects.This study was carried out to evaluate the hypolipidemic activity of virgin olive oil in experimentally induced hyperlipemic Wistar. A total of 24 rats were randomly allocated to 4 equal groups and treated as follows for 50 days: (1) Normal control (NC); that were fed with a standart diet; (2) High Cholesterol Diet Control (HCD); which received high cholesterol diet for 50 days; (3) Animals receiving high cholesterol diet for 50 days, after this period the animals are fed for eight days by the standard foodand receiving by gavage virgin olive oil (HCD+VOO) and(4) Animals fed for eight days with the standard food and receiving by gavage olive oil (VOO). High Cholesterol Diet containing yolk egg and coconut oil. Results showed that olive oil caused a significant (p < 0.01) reduction in serum levels of Total Cholesterol (TC), Triglycerides (TG), Low­Density Lipoprotein Cholesterol (LDL) and Atherogenic Index Serum (AIS). The results also demonstrated a significant (p < 0.01) increase in High­Density Lipoprotein Cholesterol (HDL). Moreover, virgin olive oil induced a significant reduction in liver lipid content. On the other hand, a High cholesterol diet induced oxidative stress was measured by estimating reduced glutathione level and amount of thiobarbituric acid reactive substances (TBARS) formed as an index of lipid peroxidation in a liver and a heart. Virgin olive oil supplementation attenuated all these variations. Our observations of the study indicate that the virgin olive oil has a significant antihyperlipidemic potential.

The prebiotic inulin modulates gut microbiota but does not ameliorate atherosclerosis in hypercholesterolemic APOE*3-Leiden.CETP mice.

Gut microbiota have been implicated in the development of atherosclerosis and cardiovascular disease. Since the prebiotic inulin is thought to beneficially affect gut microbiota, we aimed to determine the effect of inulin supplementation on atherosclerosis development in APOE*3-Leiden.CETP (E3L.CETP) mice. Female E3L.CETP mice were fed a western-type diet containing 0.1% or 0.5% cholesterol with or without 10% inulin. The effects of inulin were determined on: microbiota composition, cecal short-chain fatty acid (SCFA) levels, plasma lipid levels, atherosclerosis development, hepatic morphology and hepatic inflammation. Inulin with 0.5% dietary cholesterol increased specific bacterial genera and elevated levels of cecal SCFAs, but did not affect plasma cholesterol levels or atherosclerosis development. Surprisingly, inulin resulted in mild hepatic inflammation as shown by increased expression of inflammation markers. However, these effects were not accompanied by increased hepatic macrophage number. Analogously, inulin induced mild steatosis and increased hepatocyte size, but did not affect hepatic triglyceride content. Inulin with 0.1% dietary cholesterol did not affect hepatic morphology, nor hepatic expression of inflammation markers. Overall, inulin did not reduce hypercholesterolemia or atherosclerosis development in E3L.CETP mice despite showing clear prebiotic activity, but resulted in manifestations of hepatic inflammation when combined with a high percentage of dietary cholesterol.

ß-glucans and cholesterol (Review).

Hypercholesterolemia is one of primary risk factors of cardiovascular disease, together with metabolic syndrome, hypertension and diabetes. Although progress has been made, the search for novel methods of preventing and treating dyslipidemia is ongoing and current therapies for cardiovascular disease induce various side effects. ß­glucans are linear unbranched polysaccharides found in various natural sources, such as mushrooms. Due to their structure they are able to interact with innate immunity receptors, however they also act as dietary fibers in the digestive tract. As there are two forms of ß­glucans, insoluble and soluble forms, they are able to interact with lipids and biliary salts in the bowel and consequently reduce cholesterol levels. Therefore, they may be developed as a suitable therapeutic option to treat patients with dyslipidemia, as they are natural molecules that do not induce any significant side effects. The current review discusses the evidence supporting the effects of ß­glucans on cholesterol levels.

Xanthohumol, a hop-derived prenylated flavonoid, promotes macrophage reverse cholesterol transport.

Xanthohumol, a prominent prenyl flavonoid from the hop plant (Humulus lupulus L.), is suggested to be antiatherogenic since it reportedly increases high-density lipoprotein (HDL) cholesterol levels. It is not clear whether xanthohumol promotes reverse cholesterol transport (RCT), the most important antiatherogenic property of HDL; therefore, we investigated the effects of xanthohumol on macrophage-to-feces RCT using a hamster model as a CETP-expressing species. In vivo RCT experiments showed that xanthohumol significantly increased fecal appearance of the tracer derived from intraperitoneally injected [3H]-cholesterol-labeled macrophages. Ex vivo experiments were then employed to investigate the detailed mechanism by which xanthohumol enhanced RCT. Cholesterol efflux capacity from macrophages was 1.5-fold higher in xanthohumol-fed hamsters compared with the control group. In addition, protein expression and lecithin-cholesterol acyltransferase activity in the HDL fraction were significantly higher in xanthohumol-fed hamsters compared with the control, suggesting that xanthohumol promoted HDL maturation. Hepatic transcript analysis revealed that xanthohumol increased mRNA expression of abcg8 and cyp7a1. In addition, protein expressions of liver X receptor α and bile pump export protein were increased in the liver by xanthohumol administration when compared with the control, implying that it stimulated bile acid synthesis and cholesterol excretion to feces. In conclusion, our data demonstrate that xanthohumol improves RCT in vivo through cholesterol efflux from macrophages and excretion to feces, leading to antiatherosclerosis effects. It remains to be elucidated whether enhancement of RCT by xanthohumol could prove valuable in humans.

Chia Oil-Enriched Restructured Pork Effects on Oxidative and Inflammatory Status of Aged Rats Fed High Cholesterol/High Fat Diets.

Chia oil has the highest recognized α-linolenic acid (ALA) content. ALA is associated with beneficial changes in plasma lipids and the prevention of cardiovascular diseases. Present article aims to analyze the effect of Chia oil-enriched restructured pork (RP) on aged rats in a nonalcoholic steatohepatitis (NASH) model. Groups of six male Wistar rats (1-year old) were fed the experimental diets: control RP diet (C) noncholesterol high saturated; cholesterol-enriched high-saturated fat/high-cholesterol control RP diet (HC) with added cholesterol and cholic acid; and Chia oil- or Hydroxytyrosol RP cholesterol-enriched high-saturated fat/high cholesterol (CHIA and HxT). Total cholesterol, hepatosomatic index, Nrf2, antioxidant, and inflammation markers were determined. CHIA reduced the hypercholesterolemic effect by lowering levels similar to C; also, ameliorated redox index. CHIA, despite high polyunsaturated fatty acids (PUFA) content, reduced thiobarbituric acid reactive substances (TBARS) and induced the lowest SOD protein synthesis but not a reduction on its activity. Chia oil activated the Nrf2 to arrest the pro-oxidative response to cholesterol and aging. Endothelial nitric oxide synthase (eNOS) system was lower in HxT than in CHIA, suggesting its antiatherogenic activity and related protective effect against high PUFA. Increase in tumor necrosis factor alpha (TNFα) was partially blocked by CHIA. Chia oil has the ability to prevent oxidative damage and modify the inflammatory response, suggesting adequate regulation of the antioxidant system. Results stress the importance of incorporating ALA into the diet.

Effects of dietary Corinthian currants (Vitis vinifera L., var. Apyrena) on atherosclerosis and plasma phenolic compounds during prolonged hypercholesterolemia in New Zealand White rabbits.

Corinthian currants are a rich source of phenolic compounds, which are known to exert beneficial effects on cardiovascular disease. The hypothesis tested is whether dietary supplementation with currants attenuates atherosclerosis and affects plasma phenolics during prolonged hypercholesterolemia in rabbits. Thirty New Zealand White rabbits were fed one of four diets (normal and supplemented with 10% currants, with 0.5% cholesterol, and with 0.5% cholesterol plus 10% currants) for eight weeks. Plasma lipids, glucose and hepatic enzymes were determined. Individual phenolic compounds were identified and quantified in plasma during the dietary intervention. At the end of the study, histological examinations of aorta and liver were performed. The high-cholesterol diet resulted in hypercholesterolemia and oxidative stress, increased aspartate aminotransferase (AST) activity and induced aortic and hepatic lesion formation. Corinthian currant supplementation attenuated atherosclerotic lesions, maintained AST within the normal range and reduced oxidative stress without affecting glucose concentrations. The p-OH-benzoic and p-OH-phenylacetic acids predominated at high concentrations in plasma and remained almost constant during the study in the group that received the normal rabbit chow and the groups given food with added cholesterol either alone or supplemented with currants. Currant supplementation to the normal diet resulted in the reduced absorption of phenolic compounds, as revealed by the measurement of their plasma metabolites, suggesting a regulatory mechanism at the gut level under normal conditions.

Oral administration of alkaloid fraction from Ruta graveolens inhibits oxidative stress and inflammation in hypercholesterolemic rabbits.

CONTEXT: The anti-atherogenic effect of alkaloid fraction from Ruta graveolens Linn (Rutaceae) extract is suspected to be related to its activities of antioxidation and anti-inflammation. OBJECTIVE: This study investigated the efficacy of alkaloid fraction isolated from Ruta graveolens (AFR) in reducing oxidative damage and inflammation in hypercholesteremic rabbits. MATERIALS AND METHODS: The New Zealand white rabbits were randomly divided into three groups: Group I rabbits were fed with normal chow diet for 90 d. Group II rabbits were fed with 1% cholesterol-enriched diet. Group III rabbits were fed with 1% cholesterol-enriched diet together with AFR (10 mg/kg/daily for 90 d). RESULTS AND DISCUSSION: The results showed that on treatment with AFR significantly lowered the level of total cholesterol and LDL-C and showed an increment in the level of HDL-C. LD50 of the AFR in rats is greater than 525 mg/kg. Activities of antioxidant enzymes such as superoxide dismutase, catalase and glutathione peroxidase and GSH level were decreased in cholesterol-fed rabbit and supplementation of AFR significantly enhanced the activities of these antioxidant enzymes and GSH level. Increased activities of enzymes such as cyclooxygenase-2, 15-lipoxygenase and myeloperoxidase were significantly suppressed by AFR administration. The acute phase proteins, total WBC count and TBARS concentrations were significantly increased by hypercholesteromic diet, which were significantly decreased by AFR treatment. Histopathological studies of aorta in cholesterol-fed rabbit showed plaque formation and significant changes in aortic wall. Administration of AFR showed no changes in aortic wall. CONCLUSION: AFR reduces oxidative stress and inflammation and reduces the aortic pathology in hypercholesteromic rabbits.

Novel soybean oils differing in fatty acid composition alter immune functions of moderately hypercholesterolemic older adults.

Linoleic acid (LA) and α-linolenic acid (ALA) are essential fatty acids that play an important role in modulation of T cell proliferation. The effects of consuming novel soybean oils varying in LA:ALA ratios on T cell proliferation and inflammatory responses were assessed in older adults. Eighteen participants (>50 y old) with elevated cholesterol concentrations (3.37-4.14 mmol/L LDL cholesterol) consumed 5 experimental diets in random order for periods of 35 d. Each diet contained 30% of energy as fat, two-thirds of which was high-oleic acid soybean oil (HiOleic-SO), soybean oil (SO), low-SFA soybean oil (LoSFA-SO), hydrogenated soybean oil (Hydrog-SO), or low-ALA soybean oil (LoALA-SO), resulting in LA:ALA ratios of 2.98, 8.70, 9.69, 15.2, and 18.3, respectively. Participants had higher proliferative responses to phytohemagglutinin (PHA) compared with baseline following consumption of SO (26%; P < 0.05), LoSFA-SO (22%; P < 0.05), or HiOleic-SO (24%; P < 0.05) diets. Proliferative response was similar to the baseline after participants consumed diets with an LA:ALA ratio >10 (Hydrog-SO and LoALA-SO). Post-diet intervention, LA:ALA ratios correlated with proliferative responses to PHA (r = -0.87; P = 0.05). An optimal proliferative response was observed at an LA:ALA ratio of 8.70, with an inverse correlation between proliferative response and LA:ALA ratios >8.70. These effects were independent of changes in the production of PGE(2), inflammatory cytokines, or cytokines involved in growth of lymphocytes. These data suggest that the LA:ALA ratio modulates the proliferative ability of T lymphocytes, which may be due to subtle changes in fatty acid composition of the phospholipids in immune cells.

Effects of high molecular weight alcohols from sugar cane fed alone or in combination with plant sterols on lipid profile and antioxidant status of Wistar rats.

The effect of feeding a mixture of high molecular weight alcohols derived from sugarcane (SCA), both alone and in combination with phytosterols (PS), on changes in plasma lipids, organ cholesterol accumulation, and antioxidant status of Wistar rats was undertaken. Three separate experiments were conducted and each experiment had 3 subsets. In experiment 1, rats were fed on an AIN-76, semi-synthetic diet supplemented with 0%, 0.5%, and 5% SCA w/w. The second experiment consisted of feeding rats an atherogenic diet (AIN-76+0.5% cholesterol) containing 0%, 0.5%, and 5% SCA w/w. The third experiment consisted of feeding rats an atherogenic diet that contained 2% PS in combination with 0%, 0.5%, and 5% SCA. Rats fed the atherogenic diet exhibited significant elevations in total and low-density lipoprotein cholesterol, and significant reductions in the high-density lipoprotein/total cholesterol ratio, regardless of the presence of 0.5% or 5% SCA mixture. Serum cholesterol increased 29% to 35% in these animals compared with animals fed the nonatherogenic diets. In contrast, animals fed atherogenic diets that contained 2% PS exhibited no difference in serum lipids compared with counterparts fed nonatherogenic diets. The combined presence of SCA with PS had no effect on further lowering plasma cholesterol. No changes in C-reactive protein were observed, but plasma oxygen radical scavenging capacity values significantly (p < 0.05) decreased when rats were fed the atherogenic diets that contained the combination of PS and SCA. This result corresponded to an apparent greater (p < 0.05) susceptibility of red blood cells to oxidative stress.

A pilot study to evaluate the effect of soy isolate protein on the serum lipid profile and other potential cardiovascular risk markers in moderately hypercholesterolemic Chinese adults.

This article examines the effect of soy isolate protein on the serum lipids and other potential cardiovascular risk markers in 90 moderately hypercholesterolemic Chinese adults (64 women and 26 men, aged 25 to 70 years). Fasting blood samples were taken before and after consuming 24 g of protein supplied by soy isolate protein supplement (including 18 g soy protein and 6 g milk protein) or milk protein supplement daily for 8 weeks. Dietary intake was assessed by a 3-day record collected at baseline, week 4, and week 8 of the study. The results indicate that the two kinds of protein can modestly improve serum lipids and markers associated with obesity and inflammation.

Comparison of effects of morning versus evening administration of ezetimibe/simvastatin on serum cholesterol in patients with primary hypercholesterolemia.

BACKGROUND: Ezetimibe, a first-in-its-class inhibitor of cholesterol absorption, is an effective agent for combined use with statins to achieve low-density lipoprotein cholesterol (LDL-C) goals. Ezetimibe in combination with simvastatin as a single-tablet formulation has proven to be highly effective in reducing serum LDL-C through the dual inhibition of cholesterol absorption and biosynthesis. The effect of time of administration on efficacy of this combination therapy has not been evaluated. OBJECTIVE: To compare the effects of morning versus evening administration of ezetimibe/simvastatin on serum cholesterol levels of patients with primary hypercholesterolemia. METHODS: In this multicenter, open-label, randomized, 2-sequence, 2-period crossover study, patients with primary hypercholesterolemia randomly received ezetimibe/simvastatin 10 mg/20 mg once daily, either in the morning (within 1 hour of breakfast) or in the evening (within 1 hour of dinner) for 6 weeks. RESULTS: Data on 171 patients (87 in the morning administration group and 84 in the evening administration group) were analyzed. A significant reduction (p ≤ 0.001) in the total cholesterol, triglyceride, high-density lipoprotein cholesterol, LDL-C, apo-lipoprotein B, and high-sensitivity C-reactive protein (hs-CRP) from baseline was achieved after each treatment. Noninferiority of morning administration versus evening administration was shown in the percentage reduction of the LDL-C level from baseline (difference, -1.62%; 90% CI -4.94 to 1.70). No significant difference was found between groups with respect to the percentage of changes in other lipid parameters from baseline. Furthermore, there was no significant difference in the percentage of change in hs-CRP as an antiinflammatory marker between the morning and evening administration groups. The frequency of adverse events was similar between groups. CONCLUSIONS: Morning administration of ezetimibe/simvastatin 10 mg/20 mg is noninferior to evening administration with respect to LDL-C-lowering ability.

Grape juice concentrate prevents oxidative DNA damage in peripheral blood cells of rats subjected to a high-cholesterol diet.

The goal of the present study was to investigate whether subchronic treatment with grape juice concentrate is able to protect liver and peripheral blood cells against cholesterol-induced injury in rats. The effects of the grape juice concentrate treatment on histopathological changes, immunohistochemistry for cyclo-oxygenase-2 (COX-2), and basal and oxidative DNA damage induced by H2O2 using a single-cell gel (comet) assay were evaluated. Male Wistar rats (n 18) were divided into three groups: group 1--negative control; group 2--cholesterol at 1 % (w/w) in their diet, treated for 5 weeks; group 3--cholesterol at 1 % in their chow, treated for 5 weeks, and grape juice concentrate at 222 mg/d in their drinking-water in the final week only. The results indicated that the treatment with grape juice concentrate did not show remarkable differences regarding liver tissue in group 3 compared with group 2. However, grape juice concentrate was able to decrease oxidative DNA damage induced by H2O2 in peripheral blood cells, as depicted by the tail moment results. COX-2 expression in the liver did not show statistically significant differences (P>0·05) between groups. Taken together, the present results suggest that the administration of subchronic grape juice concentrate prevents oxidative DNA damage in peripheral blood cells.

Picrorhiza scrophulariiflora improves accelerated atherosclerosis through inhibition of redox-sensitive inflammation.

BACKGROUND: Accumulation of advanced glycation end products (AGEs) or advanced oxidation protein products (AOPPs) has been identified as a risk factor for accelerated atherosclerosis seen in diabetes and chronic kidney disease. However, little is known about the intervention for atherogenesis associated with these oxidized proteins. The rhizome of Picrorhiza scrophulariiflora (PS) has long been used to treat inflammatory diseases as a traditional medication. The study was performed to test the hypothesis that ethanol extraction of PS (EPS) may improve AGEs- or AOPPs-induced accelerated atherosclerosis in vivo. METHODS AND RESULTS: Hypercholesterolemic or normal rabbits were randomly assigned to 8 groups treated with intravenous injection of AGEs- or AOPPs-modified rabbit serum albumin (AGEs-RSA or AOPPs-RSA), unmodified RSA or vehicle in the presence or absence of EPS (10 mg/kg/2 days) gavage for 10 weeks. Compared with hypercholesterolemic rabbits without EPS treatment, EPS administration significantly decreased the aortic plaque volume and oxidized low density lipoprotein (Ox-LDL) deposition in hypercholesterolemic animals. This was accompanied by significant histological improvement including decrease of intimal and smooth muscle cell proliferation and macrophage influx in affected areas. EPS administration almost completely abolished the accelerated atherosclerosis induced by chronic treatment of AGEs- or AOPPs-RSA in both hypercholesterolemic and normal rabbits. EPS administration significantly restored the AGEs- or AOPPs-induced redox imbalance and inflammation, evidenced by decrease of plasma Ox-LDL, thiobarbituric acid reactive substances and TNF-alpha, and increase of glutathione peroxidase activity. CONCLUSION: These data suggested that EPS may improve atherosclerosis, particularly that induced by AGEs or AOPPs, through inhibition of redox-sensitive inflammation.

Effects of dietary fish oil supplementation on cellular adhesion molecule expression and tissue myeloperoxidase activity in hypercholesterolemic mice with sepsis.

This study investigated the effects of fish oil on adhesion molecule expression and tissue myeloperoxidase (MPO) activity in hypercholesterolemic mice with sepsis. There were one control and two experimental groups in this study. The control group (C) was fed a regular chow diet for 7 weeks, while hypercholesterolemia in the experimental group was induced by feeding a high-fat diet (20%, w/w) with cholesterol (2%, w/w) for 4 weeks. Then the experimental group was divided into two subgroups with identical nutrient distributions except that one subgroup was fed soybean oil (SO), while part of the soybean oil was replaced by fish oil (FO) in the other one for 3 weeks. After feeding the diets for 7 weeks, sepsis was induced in all three groups by cecal and ligation and puncture (CLP), and mice were sacrificed at 0, 6 or 24 h after CLP, respectively. The results showed that the FO group had a higher intracellular interferon-gamma/interleukin-4 ratio and lower tumor necrosis factor-alpha and monocyte chemoattractant protein-1 concentrations in peritoneal lavage fluid at 6 h after CLP than those in the C and SO groups. Lymphocyte CD11a/CD18 expressions were higher at 0 and 6 h and neutrophil CD11b/CD18 were higher at 6 h in the SO group than in the FO and C groups. The SO group had higher plasma intercellular adhesion molecule (ICAM)-1 levels than C group at 0 and 6 h, whereas no difference in ICAM-1 concentrations were observed between the C and FO groups at 0 h after CLP. Hypercholesterolemia resulted in higher tissue MPO activities. There were no differences in MPO activities in various organs between the two experimental groups. These results suggest that hypercholesterolemic mice fed FO did not exhibit immunosuppression when complicated with sepsis. FO administration reduced adhesion molecule expressions and inflammatory-related mediators at the site of injury at an early but not a late stage of sepsis. However, compared with the SO group, the influences of FO on MPO activities in various organs were not obvious in hypercholesterolemic mice with sepsis.

Electroacupuncture alters the expression of genes associated with lipid metabolism and immune reaction in liver of hypercholesterolemia mice.

Acupuncture or electroacupuncture (EA) is effective in treating various metabolism disorders. Previously we found that EA at the acupoint, Fenglong (ST40), had the cholesterol-lowering effect and regulated genes expression in liver of hypercholesterolemia mice (M Li and YZ Zhang, Int J Mol Med 2007, 19: 617-629). To explain gene expression associated with EA, suppression subtractive hybridization (SSH), combined with targeted display (TD), was used and 26 up-regulated and 24 down-regulated genes with known functions were identified in hypercholesterolemia mice liver, some of which are involved in key reactions of lipid metabolism and immune reaction. Promoting lipid metabolism and suppressing inflammation via modulating mRNA expression may be the mechanism of EA inducing modulation of cholesterol concentrations.

Oxidant stress, inflammation and atherogenesis.

Low-grade inflammation, enhanced oxidant stress and lipid peroxidation have been shown in association with increased cardiovascular risk associated with cardiovascular events. It has been hypothesized that the low-grade inflammatory state characterizing metabolic disorders such as obesity, hypercholesterolemia, type 2 diabetes mellitus and homozygous homocystinuria may be the primary trigger of thromboxane-dependent platelet activation mediated, at least in part, through enhanced lipid peroxidation. Interestingly, as the clinical course of systemic lupus erythematosus (SLE), in particular in the presence of antiphospholipid antibodies, may be complicated by vascular disease, several mechanisms contributing to vascular complications have been documented also in this setting, including enhanced lipid peroxidation and thromboxane biosynthesis. Although epidemiological studies show an inverse relationship between antioxidant vitamin intake and cardiovascular disease, several clinical trials have obtained conflicting results on the effects of vitamin E on the risk of cardiovascular events. The availability of analytical tools for measuring F2-isoprostane biosynthesis in man has improved our understanding of the interplay between lipid peroxidation and low-grade inflammation. The use of F2-isoprostane as a biochemical end-point for dose-finding studies may allow reassessing the adequacy of vitamin supplementation in different clinical settings.

The effects of chromium and copper supplementation on mitogen-stimulated T cell proliferation in hypercholesterolaemic postmenopausal women.

The purpose of this study was to analyse effects of chromium and/or copper supplementation on immune function in hypercholesterolaemic postmenopausal women. A 2 x 2 factorial research design was used and 40 subjects were supplemented with 0.394 g lactose, 200 microg Cr, 3.0 mg Cu, or 200 microg Cr and 3.0 mg Cu/d for 12 weeks. A significant interactive effect of Cr and Cu supplementation on lymphocyte proliferation was observed with ConA 50 microg/ml stimulation. After 12 weeks of supplementation, ConA-stimulated (50 microg/ml) lymphocyte proliferation was significantly lower when Cu was added to the Cr supplementation group. Moreover, ConA-stimulated (100 microg/ml) lymphocyte proliferation was significantly lower in the Cu supplementation group compared to the Cr supplementation group after 12 weeks of supplementation. These results suggest that Cu blocks enhancement of lymphocyte proliferation by Cr supplementation and that Cu supplementation has potential suppressive effects on the immune function in these subjects.

Alpha-tocopherol and probucol reduce autoantibody titer to MDA-LDL in hypercholesterolemic rabbits.

We considered the hypothesis that antioxidant supplementation that increases aortic antioxidant concentrations would reduce autoantibody titer to MDA-LDL, a measure that may indicate in vivo oxidation. We assessed autoantibody titer to MDA-LDL in rabbits before and after 5 months of treatment with a nutritionally adequate hypercholesterolemic diet alone (control) or supplemented with synthetic alpha-tocopherol or probucol. Aortic cholesterol and antioxidants were assessed at the end of treatment. alpha-Tocopherol supplementation increased the ratio of aortic alpha-tocopherol to cholesterol by 20-30-fold, while probucol supplementation increased the ratio of aortic probucol to cholesterol to 4-13 micromol/mol. Before treatment, MDA-LDL autoantibody titer averaged 5.09 +/- 0.24 with no difference among groups (p =.53 by ANOVA). However, after treatment, autoantibody titers differed among groups (p <.03 by ANOVA). Autoantibody titers were similar in rabbits supplemented with alpha-tocopherol and probucol (3.69 +/- 0.21 and 3.73 +/- 0.48, respectively, p = 0.81), and 26% (p <.009) lower in antioxidant supplemented rabbits than unsupplemented hypercholesterolemic rabbits (5.03 +/- 0.47). There was an inverse J relationship between autoantibody titer after treatment and aortic alpha-tocopherol/cholesterol and probucol/cholesterol, with minimum values for autoantibody titers above 8-10 micromol antioxidant/mmol cholesterol. The results of this study are consistent with inhibition of in vivo intra-aortic oxidation when aortic alpha-tocopherol or probucol exceed 8-10 micro;mol/mmol cholesterol.