Oxidized LDL level is related to gene expression of tumour necrosis factor super family members in children and young adults with familial hypercholesterolaemia.

OBJECTIVE: Familial hypercholesterolaemia (FH) is associated with increased risk of premature atherosclerosis. Inflammation is a key event in atherogenesis, and we have previously reported an inflammatory imbalance between tumour necrosis factor (TNF)α and interleukin-10 in children with FH. Based on the potential role of TNF-related molecules in inflammation, we investigated the regulation of other members of the TNF superfamily (TNFSF)/TNF receptor superfamily (TNFRSF) in children and young adults with FH and matched healthy controls. METHODS: Expression of TNFSF/TNFRSF genes in peripheral blood mononuclear cells (PBMCs) was quantified in children and young adults with FH prior to (n = 42) and after statin treatment (n = 10) and in controls (n = 25) by quantitative real-time polymerase chain reaction. RESULTS: First we found that, compared with controls, the mRNA levels of OX40L, BAFFR and TRAILR1 were significantly higher, whereas TRAIL and TRAILR3 were significantly lower in children and young adults with FH. Secondly, levels of oxidized low-density lipoprotein (oxLDL) were significantly raised in the FH group, and correlated with the expression of OX40L, BAFFR and TRAILR1. Thirdly, oxLDL increased mRNA levels of BAFFR, TRAILR1 and TRAILR4 in PBMCs ex vivo from individuals with FH. Fourthly, OX40, acting through OX40L, enhanced the oxLDL-induced expression of matrix metalloproteinase-9 in THP-1 monocytes in vitro. Finally, after statin treatment in children with FH (n = 10), mRNA levels of OX40L and TRAILR1 decreased, whereas levels BAFF, TRAIL and TRAILR3 increased. CONCLUSION: Our findings suggest the involvement of some TNFSF/TNFRSF members and oxLDL in the early stages of atherogenesis; this may potentially contribute to the accelerated rate of atherosclerosis observed in individuals with FH.

Sun exposure rapidly reduces plasmacytoid dendritic cells and inflammatory dermal dendritic cells in psoriatic skin.

BACKGROUND: Interferon (IFN)-α-producing plasmacytoid dendritic cells (pDCs), inflammatory CD11c+CD1c- myeloid dendritic cells (mDCs) and macrophages have been found to contribute to the pathogenesis of psoriasis. Heliotherapy is a well-established treatment modality of this disease, although the details of how the effects are mediated are unknown. OBJECTIVES: To test the hypothesis that exposure to natural sun affects pathogenic DC subsets in lesional skin. METHODS: Skin biopsies were obtained from lesional and nonlesional skin in 10 patients with moderate to severe psoriasis subjected to controlled sun exposure on Gran Canaria. Biopsies were obtained at baseline, day 2 and day 16 and examined by immunohistochemistry. RESULTS: Sixteen days of heliotherapy had excellent clinical effect on patients with psoriasis, with significant reductions in Psoriasis Area and Severity Index (PASI) scores. In lesional skin pDC numbers and expression of MxA, a surrogate marker for IFN-α, were rapidly reduced. Inflammatory CD11c+CD1c- mDCs were significantly reduced whereas resident dermal CD11c+CD1c+ mDCs were unaffected. Expression levels of the maturation marker DC-LAMP (CD208) on mDCs were significantly reduced after sun exposure, as were the numbers of lesional dermal macrophages. A decrease of dermal DC subsets and macrophages was already observed after 1 day of sun exposure. An additional finding was that DC-SIGN (CD209) is primarily expressed on CD163+ macrophages and not DCs. CONCLUSIONS: The clinical improvement in psoriasis following sun exposure is associated with rapid changes in dermal DC populations and macrophages in lesional skin, preceding the clinical effect. These findings support the concept that these DC subsets are involved in the pathogenesis of psoriasis and suggest that sun-induced clinical benefit may partly be explained by its effect on dermal DCs.

Sun exposure induces rapid immunological changes in skin and peripheral blood in patients with psoriasis.

BACKGROUND: Ultraviolet (UV) radiation has immunosuppressive effects and heliotherapy is a well-described treatment modality for psoriasis. OBJECTIVES: To characterize early sun-induced immunological changes both local and systemic in patients with psoriasis. METHODS: Twenty patients with moderate to severe psoriasis were subjected to controlled sun exposure on Gran Canaria, Canary Islands, Spain. Psoriasis Area and Severity Index (PASI) scores were evaluated. Skin biopsies were obtained from lesional and nonlesional skin in 10 patients at baseline and on day 16 and from five additional patients on day 2. Specimens were examined with immunohistochemistry and polymerase chain reaction. Blood samples were obtained from all patients at the same time points and were examined for T-cell subsets and cytokine production. RESULTS: Significant clinical improvement was achieved during the study period. CD4+ and CD8+ T cells in lesional skin were significantly reduced in both the epidermis and dermis. In contrast, dermal FOXP3+ T cells were relatively increased. In the peripheral blood skin homing cutaneous lymphocyte-associated antigen (CLA)+ T cells were significantly decreased after only 1 day in the sun and in vitro stimulated peripheral blood mononuclear cells demonstrated reduced capacity to secrete cytokines after 16 days. CONCLUSIONS: Our data show that clinical improvement of psoriasis following sun exposure is preceded by a rapid reduction in local and systemic inflammatory markers, strongly suggesting that immune modulation mediated the observed clinical effect. We cannot completely rule out that other mechanisms, such as stress reduction, may contribute, but it is extensively documented that UV irradiation is a potent inducer of immunosuppression and we therefore conclude that the observed effect was primarily due to sun exposure.

Effect of climate therapy at Gran Canaria on vitamin D production, blood glucose and lipids in patients with psoriasis.

BACKGROUND: Climate therapy (heliotherapy) of psoriasis is an effective and natural treatment. Ultraviolet radiation (UVB) from the sun improves psoriasis and induces vitamin D(3) synthesis. OBJECTIVE: The aim of the study was to investigate the effect of climate therapy on vitamin D(3) synthesis, blood glucose, lipids and vitamin B12 in psoriasis patients. METHODS: Twenty Caucasian patients (6 women and 14 men; mean age, 47.2 years; range, 24-65) with moderate to severe psoriasis [mean Psoriasis Area and Severity Index (PASI) score 9.8; range, 3.8-18.8] received climate therapy at the Gran Canarias for 3 weeks. Blood samples were drawn before and after 15 days of sun exposure. In addition, the patients' individual skin UV doses based on UV measurements were estimated. RESULTS: Sun exposure for 15 days lead to a 72.8% (+/- 18.0 SD) reduction in the PASI score in psoriasis patients. Although no direct correlation was observed between PASI score improvement and UVB dose, the sun exposure improved the vitamin D, lipid and carbohydrate status of the patients. The serum concentrations of 25-hydroxyvitamin D [25(OH)D] increased from 57.2 +/- 14.9 nmol/L before therapy to 104.5 +/- 15.8 nmol/L (P < 0.0001) after 15 days of sun exposure; the serum levels of 1,25-dihydroxyvitamin D [1,25(OH)(2)D] increased from 146.5 +/- 42.0 to 182.7 +/- 59.1 pmol/L (P = 0.01); the ratio of low-density lipoprotein cholesterol and high-density lipoprotein cholesterol decreased from 2.4 to 1.9 (P < 0.001); and the haemoglobin A(1)c (HbA(1)c) levels decreased from 5.6 +/- 1.7% to 5.1 +/- 0.3% (P < 0.0001). CONCLUSION: Climate therapy with sun exposure had a positive effect on psoriasis, vitamin D production, lipid and carbohydrate status.

Increased levels of C-reactive protein and interleukin-6 in hyperhomocysteinemic subjects.

OBJECTIVE: Elevated plasma homocysteine concentration is considered to be an independent risk factor for cardiovascular disease. However, the mechanisms by which hyperhomocysteinemia are related to vascular disease are unclear. High-sensitivity C-reactive protein (CRP), a marker of inflammation, has been reported to be an independent predictor of future myocardial infarction among clinically healthy individuals. Interleukin (IL)-6 is a regulator of CRP and has a key role in initiation of inflammation. The aim of this study was to investigate whether individuals with increased plasma homocysteine concentrations have altered levels of serum CRP and IL-6. MATERIAL AND METHODS: Serum concentrations of CRP and IL-6 were measured in 39 individuals with hyperhomocysteinemia and in 39 control subjects matched for gender, age and body mass index (BMI). In addition, the inflammatory effect of IL-6 on peripheral blood mononuclear cells was measured. RESULTS: Compared to controls, hyperhomocysteinemic subjects have elevated serum levels of CRP and IL-6 (p < or =0.001 and p < 0.005, respectively). Importantly, this raised level of IL-6 was also seen in hyperhomocysteinemic individuals without accompanying hypercholesterolemia or cardiovascular disease. IL-6 increased the release of monocyte chemoattractant protein-1 from peripheral blood mononuclear cells, with particularly enhancing effects in cells from patients with hyperhomocysteinemia. CONCLUSIONS: These data suggest that enhanced inflammation may be associated with homocysteine-related cardiovascular disease, possibly involving IL-6-related mechanisms.

Altered composition of HDL3 in FH subjects causing a HDL subfraction with less atheroprotective function.

BACKGROUND: Subjects with familial hypercholesterolemia (FH) are associated with increased risk of premature atherosclerosis and coronary artery disease (CAD). However, onset of clinically manifested CAD varies widely among subjects with heterozygous FH. The purpose of this study was to investigate whether FH subjects with an identical mutation in the low-density lipoprotein (LDL) receptor gene have a high-density lipoprotein (HDL)3 that is characterized by a less atheroprotective functions than that of healthy controls and within subgroups of FH. DESIGN: Twenty-two adults <75 years of age with FH and 17 healthy sex- and age-matched controls were included. HDL3 was isolated and the composition was characterized from each subject, and its ability to suppress tumor necrosis factor(TNF)-alpha stimulated expression of ICAM-1 on HUVEC was investigated. In addition, plasma level of soluble sICAM-1 and VCAM-1 was measured. RESULTS: Compared to controls, FH subjects had lower content of phospholipids in their HDL3 subfraction and a higher serum ICAM-1 level. No differences in sVCAM-1 were observed. HDL3 isolated from FH with body mass index(BMI)>25 and from FH subjects with premature CAD contained higher content of triglycerides compared to the HDL3 from FH subjects with BMI<25 and without CAD, respectively. Most important, when testing the function of HDL3 in the two FH subgroups characterized by elevated BMI and premature CAD, lower inhibition of ICAM-1 expression on HUVEC was observed. CONCLUSIONS: The altered composition of HDL3 from FH subjects with BMI>25 and FH subjects with premature CAD may be responsible for a HDL3 subfraction with less protective properties assessed as inhibition of ICAM-1 expression on HUVEC consequently leading to more proatherogenic endothelial surface.

CXC-chemokines in coronary artery disease: possible pathogenic role of interactions between oxidized low-density lipoprotein, platelets and peripheral blood mononuclear cells.

CXC-chemokines may be involved in atherogenesis. Herein we examined the possible role of CXC-chemokines in the inflammatory interactions between oxidized (ox-) low-density lipoprotein (LDL), platelets and peripheral blood mononuclear cells (PBMC) in 15 patients with coronary artery disease (CAD) without 'traditional' risk factors and 15 carefully matched controls. Our main findings were: (a) ox-LDL stimulated the release of the CXC-chemokines interleukin (IL)-8, ENA-78 and GRO-alpha from PBMC, particularly in CAD. (b) In platelets, ox-LDL induced release of ENA-78 and, when combined with SFLLRN, also of GRO-alpha, with significantly higher response in CAD. (c) Platelet-rich plasma, especially when costimulated with ox-LDL, enhanced the release of IL-8 from PBMC, particularly in CAD patients. (d) Freshly isolated PBMC showed markedly increased IL-8 mRNA expression in CAD patients. Our findings suggest enhanced inflammatory interactions between ox-LDL, platelets and PBMC in CAD patients involving CXC-chemokine related mechanisms, possible contributing to atherogenesis in these and other CAD patients.

Expression of matrix metalloproteinase-9 in mononuclear cells of hyperhomocysteinaemic subjects.

Atherosclerotic plaque instability and rupture requires extracellular matrix modification, a complex process regulated by matrix metalloproteinases (MMPs). We hypothesized that homocysteine's atherogenic effects may involve MMP-mediated mechanisms. Our results showed the following: (i) Compared with healthy control subjects (n = 9), patients with hyperhomocysteinaemia (n = 9) had elevated mRNA levels of MMP-9 and tissue inhibitors of metalloproteinases-1 (TIMP-1) in freshly isolated peripheral blood mononuclear cells (PBMCs), which were positively correlated with homocysteine and negatively correlated with folate and vitamin B12 levels. (ii) Peripheral blood mononuclear cells obtained from these patients released markedly enhanced the amount of MMP-9 upon oxidized LDL (oxLDL) stimulation, whereas no such enhancing effect was seen in cells from healthy controls. (iii) During folic acid 6 weeks' treatment, normalization of homocysteine levels was accompanied by a significant reduction in mRNA levels of MMP-9 and TIMP-1 in PBMCs, as well as a marked reduction in oxLDL-stimulated release of MMP enzyme activity. These novel findings may suggest that homocysteine exerts its atherogenic effect in part by elevating levels and activity of MMPs, which in turn may enhance matrix degradation, potentially promoting atherogenesis and plaque instability. Moreover, our findings suggest that folic acid supplementation may down-regulate these inappropriate responses in these patients.

Effect of folic acid treatment on endothelium-dependent vasodilation and nitric oxide-derived end products in hyperhomocysteinemic subjects.

PURPOSE: An elevated plasma homocysteine concentration is an independent risk factor for cardiovascular diseases. In this study, we tested the hypothesis that hyperhomocysteinemia induces endothelial dysfunction mediated, at least in part, through nitric oxide-dependent mechanisms and that folic acid supplementation improves endothelial function in hyperhomocysteinemic subjects. SUBJECTS AND METHODS: Endothelial function was evaluated in healthy controls and hyperhomocysteinemic subjects by measuring plasma levels of the nitric oxide-derived end products nitrite and nitrate and by assessing vasodilatory responses in the skin microcirculation and forearm vasculature. In the subjects with hyperhomocysteinemia, these measurements were repeated after 6 weeks and 12 months of folic acid supplementation. RESULTS: Compared with healthy controls, hyperhomocysteinemic subjects had significantly lower median plasma levels of nitric oxide-derived end products (12.1 microM [range 4.4 to 41.8] versus 24.6 microM [13.6 to 53.2]; P <0.001), a significantly lower endothelium-dependent vasodilatory response to acetylcholine (P <0.01), hyperemic response in the microcirculation (P <0.01), and total forearm blood flow during reactive hyperemia (P = 0.01). There was no significant difference in the endothelium-independent response. Folic acid treatment for 12 months increased the plasma level of nitric oxide-derived end products by 121% (95% confidence interval [CI], 72% to 170%), the vasodilatory response to acetylcholine by 124% (95% CI, 36% to 212%), and the ischemia-mediated hyperemic responses in the microcirculation by 60% (95% CI, 25% to 96%) and in the forearm vasculature by 47% (95% CI, 21% to 73%). CONCLUSIONS: Homocysteine appears to induce its atherogenic effect, at least in part, by depressing endothelial function, possibly through nitric oxide-dependent mechanisms. This effect can be reversed by folic acid supplementation.

Reduction of leptin gene expression by dietary polyunsaturated fatty acids.

Supplementation with n-3 polyunsaturated fatty acids (PUFA) for 6 weeks did not alter plasma leptin concentrations in male smokers. Changes in dietary intake of saturated fatty acids (FA) correlated positively, whereas changes in the intake of PUFA correlated negatively to changes in plasma leptin levels. A 3-week n-3 PUFA-enriched diet, as compared with a 3-week lard-enriched diet, induced lower plasma leptin concentration and reduced leptin mRNA expression in rat epididymal adipose tissue. In the human trophoblast cell line (BeWo), n-3 PUFA had a dose- and time-dependent effect on leptin expression. One mM of eicosapentaenoic acid or docosahexaenoic acid (DHA) reduced leptin expression by 71% and 78%, respectively, as compared with control, after 72 h. There was no effect on expression of the signal transducing form of the leptin receptor. In BeWo cells transfected with the human leptin promoter, we found that n-3 PUFA reduced leptin promoter activity; in contrast saturated and monounsaturated FA had no effect on leptin promoter activity. The transcription factors peroxysomal proliferator activated receptor gamma and sterol regulatory element binding protein-1 mRNAs were reduced after incubation with n-3 PUFA, whereas the expression of CCAAT/enhancer binding protein alpha was unchanged. DHA-reduced leptin expression was abolished in BeWo cells grown in cholesterol-free medium. In conclusion, n-3 FA decreased leptin gene expression both in vivo and in vitro. The direct effects of PUFA on leptin promoter activity indicate a specific regulatory action of FA on leptin expression.

Effect of Norwegian fish powder on risk factors for coronary heart disease among hypercholesterolemic individuals.

BACKGROUND AND AIM: Numerous studies suggest an association between high intake of fatty fish and reduced risk of coronary heart disease. Very long-chain omega-3 fatty acids are thought to be responsible for the benefits observed, though other fatty fish components may act in concert with them. Norwegian fish powder is a dry herring product that contains essential amino acids, marine omega-3 fatty acids, vitamins and minerals. The aim of the present study was to determine whether it has beneficial effects on risk factors for coronary heart disease in man. METHODS AND RESULTS: A single center, randomized, double-blind, parallel-treatment study was carried out for 12 weeks. Subjects with primary hypercholesterolemia were randomly allocated to 10 g fish powder or placebo (20 tablets/day). Participants were instructed to follow National Cholesterol Education Program (NCEP) Step I Diet during a 4-week diet run-in phase and during the study. Concentrations of lipids, lipoproteins, hemostatic variables and endothelial cell markers were determined before and after supplementation. Our data showed that the fish powder supplement was well tolerated. A significant decrease and increase respectively were observed in plasma alpha-linolenic acid (p = 0.03) and docosahexaenoic acid (DHA) (p = 0.03). Concentrations of lipids, lipoproteins, homocysteine, factor VII, fibrinogen, tissue plasminogen activator (tPA), plasminogen activator inhibitor (PAI)-1, soluble intercellular adhesion molecule (ICAM)-1, P-selectin and interleukin (IL)-8 were not beneficially affected. CONCLUSIONS: Fish powder supplementation does not seem an effective approach to improve risk factors for coronary heart disease in hypercholesterolemic subjects following the NCEP Step I Diet.

Doxazosin treatment and peroxidation of low-density lipoprotein among male hypertensive subjects: in vitro and ex vivo studies.

Doxazosin is an antihypertensive drug that gives rise to 6- and 7-hydroxydoxazosin during hepatic metabolism. The structures of the hydroxymetabolites suggest that they may possess antioxidative properties. The aim of the present study was to examine whether doxazosin and 6- and 7-hydroxydoxazosin were able to scavenge free radicals and whether these compounds might protect low-density lipoprotein (LDL) against in vitro and ex vivo oxidation. Both 6- and 7-hydroxydoxazosin showed radical scavenging capacity as assessed by measuring scavenging of 1,1-diphenyl-2-picrylhydrazyl radicals. In vitro incubation with 10 microM 6- and 7-hydroxydoxazosin significantly reduced human mononuclear cell-mediated oxidation of LDL, measured as the formation of lipid peroxides and the relative electrophoretic mobility of LDL (to 10 and 6% of the control, respectively). Furthermore, formation of conjugated dienes in LDL during Cu2+-induced oxidation was significantly reduced in the presence of 5 microM 6- and 7-hydroxydoxazosin (to 28% of tmax [time to maximum] of control). However, treatment of hypertensive patients with increasing doses of doxazosin (from 1 to 8 mg/day) for 8 weeks altered neither Cu2+-catalyzed, 2,2'azobis-(2-amidinopropane hydrochloride)-initiated, nor cell-mediated oxidation of patient LDL ex vivo. Furthermore, the total antioxidative capacity of plasma was unaffected by treatment. In conclusion, the present study shows that 6- and 7-hydroxydoxazosin have radical scavenging properties and protect LDL against in vitro oxidation. However, treatment of hypertensive male subjects with increasing doses of doxazosin for 8 weeks did not affect ex vivo oxidation of LDL.

Plasma homocysteine concentration related to diet, endothelial function and mononuclear cell gene expression among male hyperlipidaemic smokers.

BACKGROUND: Elevated plasma concentration of homocysteine is an independent risk factor for development of cardiovascular diseases. MATERIALS AND METHODS: We evaluated potential links between homocysteine and atherothrombogenesis by relating the plasma concentration of homocysteine to (i) dietary antioxidants and omega-3 fatty acids (and determined influence of intervention with antioxidants or omega-3 fatty acids); (ii) markers of endothelial cell function; and (iii) peripheral blood mononuclear cell mRNA levels. RESULTS: We observed an inverse relationship between the plasma homocysteine concentration and dietary intake of vegetables, vitamin C and beta-carotene and between homocysteine and the serum concentration of folate, vitamin B12 and omega-3 fatty acids. Intervention with antioxidants or omega-3 fatty acids did not affect plasma homocysteine concentration. The plasma levels of cysteinylglycine and vitamin B12 correlated positively with circulating E-selectin and VCAM-1, respectively, whereas folate in serum and blood correlated negatively with P-selectin. A negative correlation was found between the concentrations of homocysteine and von Willebrand factor. Negative and positive correlations were found between plasma homocysteine and the mononuclear cell mRNA levels of peroxisome proliferator activated receptor delta (PPAR delta) and c-myc respectively. A negative correlation was also found between plasma homocysteine and mononuclear cell mRNA levels of the proteoglycan serglycin. Homocysteine was not correlated with serum activity of glutathione peroxidase or with the mRNA level of glutathione peroxidase in mononuclear cells. CONCLUSION: The plasma homocysteine level was negatively correlated with dietary intake of vegetables, including vitamins C and E, and serum omega-3 fatty acids, whereas supplementation with antioxidants or omega-3 fatty acids did not affect plasma homocysteine concentration. Homocysteine was not associated with circulating adhesion molecules or increased procoagulant activity, but homocysteine may alter mononuclear cell gene expression. Cysteine showed no significant correlation with these parameters.

Effects of omega-3 fatty acids and/or antioxidants on endothelial cell markers.

BACKGROUND: Increased expression of cell adhesion molecules and increased procoagulant activity of the vascular endothelium have been postulated to characterize dysfunctional endothelium. The cellular effects of n-3 fatty acids (n-3 FAs) and antioxidants are still not clarified. METHODS: In a randomized, factorial two-by-two design study, we have investigated 41 male smokers with hyperlipidaemia before and after 6 weeks of supplementation with either n-3 FAs (4.8 g daily) or placebo with the addition of antioxidants (150 mg of vitamin C, 75 mg of vitamin E and 15 mg of beta-carotene daily) or placebo with regard to the effects on some endothelial cell markers: thrombomodulin (sTM), von Willebrand factor (vWF), tissue plasminogen activator antigen (tPAag) and soluble forms of the cell adhesion molecules E-selectin, P-selectin and vascular cell adhesion molecule 1 (VCAM-1). RESULTS: In the n-3 FA group, significant reductions in the plasma levels of vWF (P = 0.034) and sTM (P < 0.001) were demonstrated compared with placebo, whereas increased levels were found for E-selectin (P = 0.001) and VCAM-1 (P = 0.010). In the antioxidant group, no differences in changes were noted for any of the variables. CONCLUSION: The reduction in the levels of sTM and vWF with n-3 FA supplementation could indicate an improvement with regard to the haemostatic markers of endothelial dysfunction, whereas the simultaneous increase in the soluble forms of E-selectin and VCAM-1 may suggest an adverse effect on the inflammatory system. The antioxidants seem to be neutral in their effect on these endothelial cell markers in our study population of smokers. The interpretation of the soluble forms of these molecules are, however, still debatable.

Effect of a coffee lipid (cafestol) on cholesterol metabolism in human skin fibroblasts.

Consumption of boiled coffee promotes an elevation of plasma cholesterol concentration in humans. The active compounds found in the lipid fraction of the coffee have been identified as the diterpenes cafestol and kahweol. We have studied the effects of pure cafestol on cholesterol metabolism in human skin fibroblasts (HSF). The uptake of [125I]-labeled tyramine cellobiose-labeled low density lipoprotein ([125I]TC-LDL) was decreased by about 50% (P< 0.05) after 18 h preincubation time with cafestol (20 microg/ml), as compared to the control cells. The specific binding of radiolabeled LDL was reduced by 54% (P < 0.05) after preincubation for 18 h with cafestol. A reduced amount of LDL receptors was demonstrated by a protein-normalized Scatchard plot analysis (20% decrease in Bmax) as well as by immunoblotting (25%) after cafestol incubation. No significant effect was observed on the level of mRNA for the LDL receptor after 11 and 23 h incubation with cafestol. Furthermore, we transfected HSF cells with a promoter region for the LDL receptor gene linked to a reporter gene, chloramphenicol acetyl transferase (CAT). No change was seen in the CAT activity after incubation with cafestol (20 microg/ml). Moreover, cafestol caused a 2.3-fold (P < 0.05) higher incorporation of radiolabeled [14C]oleic acid into cholesteryl esters after 24 h incubation, as compared to control cells, suggesting an increased acyl-CoA:cholesterol acyl transferase (ACAT) activity. Incorporation of [14C]acetate into cholesterol was reduced by approximately 40% (P < 0.05) with cafestol (20 microg/ml), as compared to control after 24 h preincubation, indicating a decreased 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase activity. Our results suggest that intake of cafestol may cause increased concentration of plasma cholesterol via the down-regulation of low density lipoprotein receptors by post-transcriptional mechanisms.

Peroxidation of LDL from combined-hyperlipidemic male smokers supplied with omega-3 fatty acids and antioxidants.

The effects of marine omega-3 polyunsaturated fatty acids (FAs) and antioxidants on the oxidative modification of LDL were studied in a randomized, double-blind, placebo-controlled trial. Male smokers (n = 41) with combined hyperlipidemia were allocated to one of four groups receiving supplementation with omega-3 FAs (5 g eicosapentaenoic acid and docosahexaenoic acid per day), antioxidants (75 mg vitamin E, 150 mg vitamin C, 15 mg beta-carotene, and 30 mg coenzyme Q10 per day), both omega-3 FAs and antioxidants, or control oils. LDL and human mononuclear cells were isolated from the patients at baseline and after 6 weeks of supplementation. LDL was subjected to cell-mediated oxidation by the patients' own mononuclear cells, as well as to Cu(2+)-catalyzed and 2,2'-azobis-(2-amidinopropane hydrochloride) (AAPH)-initiated oxidation. Extent of LDL modification was measured as lag time, the formation rate of conjugated dienes (CDs), the maximum amount of CDs formed, formation of lipid peroxides, and the relative electrophoretic mobility of LDL on agarose gels. Dietary supplementation with omega-3 FAs increased the concentration of total omega-3 FAs in LDL and reduced the concentration of vitamin E in serum. The omega-3 FA-enriched LDL particles were not more susceptible to Cu(2+)-catalyzed, AAPH-initiated, or autologous cell-mediated oxidation than control LDL. In fact, enrichment with omega-3 FAs significantly reduced the formation rate of CDs when LDL was subjected to AAPH-induced oxidation. Supplementation with moderate amounts of antioxidants significantly increased the concentration of vitamin E in serum and increased the resistance of LDL to undergo Cu(2+)-catalyzed oxidation, measured as increased lag time, reduced formation of lipid peroxides, and reduced relative electrophoretic mobility compared with control LDL. Supplementation with omega-3 FAs/antioxidants showed oxidizability of LDL similar to that of control LDL and omega-3 FA-enriched LDL. In conclusion, omega-3 FAs neither rendered the LDL particles more susceptible to undergo in vitro oxidation nor influenced mononuclear cells' ability to oxidize autologous LDL, whereas moderate amounts of antioxidants protected LDL against oxidative modification.

Omega-3 and omega-6 fatty acids in the insulin resistance syndrome. Lipid and lipoprotein metabolism and atherosclerosis.

Dietary fatty acids appear to be of significant importance for several of the most-common diseases in modern societies. To obtain more knowledge about the health consequences of dietary fatty acids, we depend upon a better understanding of the mechanisms of action of these fatty acids in vivo. With regard to the IRS, omega-3 PUFA may exert beneficial effects upon many of the associated pathophysiological metabolic changes. Omega-3 PUFA reduce fasting and postprandial TG, may improve insulin sensitivity (as shown in animal experiments), decrease platelet and leukocyte reactivity, alter immunological functions, and may slightly decrease blood pressure. Omega-3 PUFA may also beneficially influence vessel wall characteristics and blood rheology. Furthermore, both types of PUFA (omega-3 and omega-6) have been shown to inhibit cardiac arrhythmias in animals. The role of omega-3 PUFA in blood clotting and fibrinolysis still remains controversial, whereas omega-6 fatty acids may lead to increased oxidation of lipoproteins. Regardless of the effects on LDL oxidizability, both types of PUFA have shown beneficial effects on the development of atherosclerosis. As yet, little is known about the effect of specific omega-6 fatty acids with respect to the IRS. Potential adverse effects of dietary PUFA must not be neglected, but should be viewed in light of the beneficial effects of these agents.

Effect of hormone replacement therapy on the susceptibility of low-density lipoprotein to oxidation among postmenopausal hypercholesterolaemic women.

The effect of sequential combined hormone replacement therapy on the susceptibility of low-density lipoprotein to oxidative modification was investigated in a double-blind, randomized placebo-controlled study. Hypercholesterolaemic, postmenopausal women were supplemented with 17 beta-oestradiol and norethisterone acetate (n = 13 subjects) or placebo capsules (n = 15 subjects) for 12 weeks. They were instructed to follow the American Heart Association step one diet. Low-density lipoprotein, isolated before and after treatment, was subjected to copper-catalysed lipid peroxidation. There were no significant differences between low-density lipoprotein from the hormone replacement therapy and placebo groups, as assessed by measuring the lag time for formation of conjugated dienes, the rate of formation and the amount of conjugated dienes formed, the amount of lipid peroxides generated, and the relative electrophoretic mobility at baseline and after treatment. Dietary records showed that the subjects were consuming similar amounts of fat and vitamins. No major differences were found in the fatty acid pattern of low-density lipoprotein from the two groups. In conclusion, the results indicated that hormone replacement therapy with 17 beta-oestradiol sequentially combined with norethisterone acetate in non-smoking, hypercholesterolaemic, postmenopausal women has no protective effect on the susceptibility of low-density lipoprotein to copper-catalysed modification in vitro.