Eleni Bairaktari

Increased serum levels of interleukin-1β in the systemic circulation of patients with essential hypertension: Additional risk factor for atherogenesis in hypertensive patients?☆

The dysfunction of the immune system has been implicated in the cause of essential hypertension (EH). On the other hand, interleukin- 1beta (IL-1beta) has strongly been involved in the pathogenesis of atheromatosis, whereas our preliminary experiments in serum samples from hypertensive patients before any drug therapy have shown the presence of high concentrations of IL-1beta and the absence of interleukin-2 (IL-2). The aim of this study was first to confirm our preliminary findings and second to investigate the possible interrelation(s) among the parameters studied, particularly between the immunologic markers and the blood pressure or the lipid parameters, because so far there are no data regarding the possible participation of IL-1beta in the cascade phenomena presented during the process of EH such as atherogenesis. Serum samples from 28 consecutive unselected patients with EH before any drug administration or after discontinuation of the antihypertensive therapy for at least 4 weeks, 31 normotensive patients with familial hypercholesterolemia (FH, disease control group), and 35 healthy individuals In a control group matched for age and sex were investigated for the presence of IL-1beta (commercial enzyme immunoassay), soluble IL-2 receptors (slL-2Rs, sandwich enzyme-linked immunosorbent assay set up in our laboratory), and some of the acute phase proteins by nephelometry. In addition, total cholesterol, triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, apolipoproteins A1 and B, and lipoprotein (a) were determined by standard methods. The data were analyzed by unpaired t test, Mann Whitney-U, chi-squared analysis after Yates correction, analysis of variance, or Kruskal-Wallis where applicable. Correlation coefficient was calculated by simple regression analysis (r) or nonparametric Spearman correlation coefficient (rs). We found that (1) none of the patients had increased concentrations of sIL-2Rs, and (2) the IL-1beta levels significantly differed in the three groups (p = 0.0001). In more detail, the concentrations of IL-1beta were significantly higher in patients with EH compared with those in patients with FH (p < 0.0005) and the healthy control group (p = 0.0001). By contrast, the IL-1beta concentrations did not differ between patients with FH and the healthy control group. (3) Sixteen (57.1%) patients with EH and only 6 (19.4%) patients with FH (p < 0.01) had increased levels of IL-1beta, and (4) the IL-1beta was not correlated with the acute phase reactants or the lipid parameters in the groups studied. However, the group of patients with EH and increased IL-1beta levels had significantly higher mean concentrations of triglycerides (p < 0.05) and significantly lower mean concentrations of high-density lipoprotein cholesterol (p < 0.05) than those who had IL-1beta levels lower than the cutoff point. (5) The IL-1beta concentrations were positively though slightly correlated with the mean blood pressure only in the group of patients with EH (r = 0.38, p < 0.05). This study demonstrated the presence of high concentrations of IL-1beta and the absence of indicators of cellular immune activation in the systemic circulation of patients with EH, suggesting that this cytokine may be involved in the pathogenesis of EH. In addition, this study showed that the high levels of IL-1beta were associated with lipid indicators of atheromatosis only in the group of patients with EH. More studies are required in an attempt to address whether IL-1beta could have a pathogenetic importance in EH. Taking into account these findings, however, it can be suggested that the presence of high IL-1beta levels may be an additional and perhaps independent risk factor for atheromatosis in patients with EH.

Increased activity of platelet-activating factor acetylhydrolase in low-density lipoprotein subfractions induces enhanced lysophosphatidylcholine production during oxidation in patients with heterozygous familial hypercholesterolaemia

Patients with heterozygous familial hypercholesterolaemia (FH) have elevated plasma concentrations of low‐density lipoprotein (LDL) and develop premature atherosclerosis. There is increasing evidence that oxidative modification of LDL is important for the pathogenesis of atherosclerosis, and the LDL‐associated platelet‐activating factor acetylhydrolase (PAF‐AH) seems to play a key role in LDL oxidation by hydrolysing the oxidized phospholipids of phosphatidylcholine (PC) and producing lysophosphatidylcholine (lyso‐PC). We measured the total serum and high‐density lipoprotein (HDL) levels of PAF‐AH activity and studied the distribution of PAF‐AH activity among three LDL subfractions isolated by gradient ultracentrifugation in 15 patients with heterozygous FH and 13 normolipidaemic control subjects. We also determined the lyso‐PC production in each LDL subfraction during Cu2+‐induced oxidation in vitro. The total serum PAF‐AH activity in heterozygous FH patients was significantly higher than in control subjects, whereas the HDL‐associated PAF‐AH activity, expressed as a percentage of total serum PAF‐AH activity, was significantly lower in the FH patients than in control subjects (13.9 ± 6.6% vs. 30.6 ± 4.4%, P < 0.001). Among the LDL subfractions, the PAF‐AH activity in both normolipidaemic control subjects and FH patients, expressed as nmol mg−1 protein min−1, was significantly higher in the LDL3 subfraction (33.1 ± 4.8 and 53.4 ± 11.5 respectively) than in the LDL2 (18.6 ± 5.3 and 26.8 ± 10.4 respectively, P < 0.0001 for both comparisons) and LDL1 subfractions (5.1 ± 1.5 and 7.8 ± 2.6, respectively, P < 0.0001 for both comparisons). Additionally, the enzyme activity in each LDL subfraction of the heterozygous FH patients was significantly higher than in control subjects (P < 0.02 for LDL1, P < 0.03 for LDL2 and P < 0.0001 for LDL3). No difference was observed in the susceptibility to oxidation of each LDL subfraction among the heterozygous FH patients and the normolipidaemic control subjects. During oxidation, the PAF‐AH activity decreased, whereas the lyso‐PC levels significantly increased in all subfractions of both groups. The lyso‐PC/sphingomyelin molar ratio in each LDL subfraction of the FH patients 3 h after the onset of the oxidation was significantly higher than in control subjects [0.38 ± 0.05 and 0.27 ± 0.04, respectively, for LDL1 (P < 0.006), 0.47 ± 0.08 and 0.39 ± 0.03, respectively, for LDL2 (P < 0.04), 0.55 ± 0.11 and 0.42 ± 0.06, respectively, for LDL3 (P < 0.02)]. Our results show that heterozygous FH patients exhibit higher PAF‐AH activity than control subjects in all LDL subfractions, resulting in higher lyso‐PC production during oxidation, which confers on these subfractions higher biological potency. This phenomenon, in combination with the diminished anti‐atherogenic and antioxidant capability of HDL in these patients due to the relatively low HDL‐cholesterol levels compared with LDL‐cholesterol levels and, consequently, the relatively low HDL‐associated PAF‐AH activity, could contribute to the higher atherogenicity and incidence of coronary artery disease observed in FH patients.

Evaluation of Methods for the Measurement of Low-Density Lipoprotein Cholesterol

A high concentration of low-density lipoprotein cholesterol (LDL-C) in plasma is one of the strongest risk factors for atherosclerotic cardiovascular disease and mortality. The most common approach to determining LDL-C in the clinical laboratory is the Friedewald calculation. There is an increased interest to improve the accuracy of LDL-C estimated by this equation. The expert panel convened by National Cholesterol Education Program has recommended the development of accurate direct methods to measure LDL-C. Several homogeneous and fully automated methods have been introduced in recent years that show improved precision and accuracy over earlier methods, especially the Friedewald calculation. Each of the atherogenic particles in plasma—very-low, intermediate-, and low-density lipoprotein—as well as lipoprotein (a), contain one molecule of apolipoprotein B (apoB) and thus, plasma total concentration of apoB reflects the number of atherogenic particles. Several studies suggested that the measurement of apoB could improve the prediction of risk of coronary artery disease. Thus, in addition to the newly developed direct assays, alternative calculation procedures have been proposed that also take into consideration total serum apoB concentration for the estimation of LDL-C and the presence of small, dense LDL particles. The new generation of homogenous methods for the measurement of LDL-C and the use of serum apoB concentration for the estimation of LDL-C can contribute to the accurate LDL-C determination.

Estimation of LDL cholesterol based on the Friedewald formula and on apo B levels.

OBJECTIVES The plasma apolipoprotein B (apo B) concentrations have been considered to be a more accurate representation of atherogenic particles and it has been proposed that the formula LDL-C (mmol/L) = 0.41TC - 0.32TG + 1.70apo B - 0.27 is reliable for the estimation of LDL-C (Clin Chem 1997; 43: 808-15). We undertook the present study to investigate the reliability of this formula in a large number of hyperlipidemic patients. DESIGN AND METHODS 1) The Friedewald formula (LDL-F) and the apo B-based formula (LDL-B) were compared with the beta-quantification reference procedure in 130 individuals with a wide range of total cholesterol (TC) and triglyceride (TG) levels, and 2) the LDL-C levels obtained by the Friedewald formula were compared with those calculated by the apo B-based formula in 1010 individuals attending our outpatient lipid clinic. RESULTS The LDL-F and the LDL-B formulae for LDL-C estimation were found to be in good agreement with the beta-quantification (r = 0.96 and 0.97, respectively). The bias of each method plotted as a function of TG (up to 4.52 mmol/L) was found positive for the LDL-F, whereas the LDL-B was independent of the concentrations of TG. When a large number of individuals were examined, a good correlation between the two equations was found (n = 1010, r = 0.98). The difference between the two methods was not correlated with serum TG levels. However, it was correlated to serum TC, and apo B levels. CONCLUSIONS The LDL-B formula is a more reliable and accurate method than the LDL-F formula, especially at TG levels >2.26 mmol/L, although it underestimates LDL-C concentrations. Furthermore, this equation can be used in hypertriglyceridemic patients (TG >4.52 mmol/L) in whom the Friedewald equation is inaccurate.

Hypomagnesemia and concurrent acid–base and electrolyte abnormalities in patients with congestive heart failure

Patients with severe decompensated congestive heart failure (CHF) commonly exhibit acid–base and electrolyte disturbances mainly due to the activation of several neurohumoral mechanisms as well as to drugs regularly used in this population. Magnesium deficit is not infrequently observed in CHF patients but its pathophysiology remains less well‐studied as compared with other electrolyte alterations, such as hypokalemia. However, there is evidence that early detection and correction of magnesium abnormalities could obviate potentially deleterious arrhythmogenic effects.

Effect of micronized fenofibrate and losartan combination on uric acid metabolism in hypertensive patients with hyperuricemia

It has been reported that micronized fenofibrate and losartan can significantly decrease serum uric acid levels by augmenting uric acid excretion. We undertook this study to evaluate the effects of the combination treatment with micronized fenofibrate and losartan in nondiabetic hypertensive dyslipidemic patients with hyperuricemia (serum uric acid, >7 mg/ dl). A total of 25 patients (15 men, 10 women) aged 21-66 years was studied. In all patients, serum lipid parameters, including Lp(a), fibrinogen, and uric acid levels, as well as fractional excretion of uric acid (FEUA) were obtained before treatment, 8 weeks after micronized fenofibrate treatment (200 mg daily), and 8 weeks after combination therapy with micronized fenofibrate (200 mg daily) and losartan (50 mg daily). Fenofibrate alone significantly decreased total cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, Apo B, Lp(a), fibrinogen, and uric acid levels (from 7.6+/-0.55 to 5.6 +/-0.5 mg/dl; p < 0.0001) and increased high-density lipoprotein (HDL) cholesterol, Apo A1, and FEUA (from 6.5+/-1.8% to 12.2+/-4%; p < 0.0001). The addition of losartan beyond the decrease in blood pressure values did not significantly alter serum metabolic parameters. However, a small additional decrease in serum uric acid levels (from 5.6+/-0.5 to 4.9+/-1 mg/dl; p < 0.05) was found because of a further increase in FEUA (from 12.2+/-4% to 14+/-5.5%; p < 0.05). It is concluded that the combination of micronized fenofibrate and losartan is useful for the management of patients with multiple metabolic abnormalities, including hyperuricemia.

Effect of Fenofibrate on Serum Inflammatory Markers in Patients With High Triglyceride Values

Background: Atherosclerosis is the leading cause of death in developed countries. Although the mechanisms that underlie this process are not well defined, it has been proposed that atherosclerosis is mainly an inflammatory disease. In this context, a number of inflammatory markers have been studied for their ability to predict future cardiovascular events in asymptomatic individuals or patients with established atherosclerotic disease. Methods and Results: The aim of our study was to evaluate the effect of micronized fenofibrate on serum inflammatory markers, such as C-reactive protein, fibrinogen, and plasma platelet-activating factor acetylhydrolase (PAF-AH) in patients with high triglyceride values. An analysis of baseline values revealed that hypertriglyceridemic patients (n = 58) exhibit an atherogenic phenotype, characterized not only by elevated lipid values but also by high concentrations of serum inflammatory markers. Along with the improvement in serum lipid profile (reduction in triglycerides and total cholesterol, low-density lipoprotein, and nonhigh-density lipoprotein-cholesterol, with a concomitant increase in high-density lipoprotein-cholesterol levels), fenofibrate administration significantly reduced the values of serum inflammatory markers by 34%, 9.5%, and 24.8% for C-reactive protein, fibrinogen, and plasma PAF-AH, respectively. However, with the exception of PAF-AH, these reductions in inflammatory markers were not correlated with the changes in lipid values. Conclusions: In addition to its well-known hypolipidemic effects, fenofibrate may also possess significant anti-inflammatory properties that can contribute its antiatherogenic effect.

The Combination of Nebivolol plus Pravastatin is Associated with a More Beneficial Metabolic Profile Compared to that of Atenolol plus Pravastatin in Hypertensive Patients with Dyslipidemia: A Pilot Study

Nebivolol, a selective β1-lipophilic blocker, achieves blood pressure control by modulating nitric oxide release in addition to b-blockade. This dual mechanism of action could result in minimum interference with lipid metabolism compared to atenolol, a classic (β1-selective blocker. Hypertensive patients commonly exhibit lipid abnormalities and frequently require statins in combination with the anti-hypertensive therapy. We conducted this trial in order to clarify the effect on the metabolic profile of β-blocker therapy with atenolol or nebivolol alone, or in conjunction with pravastatin. Thirty hypertensive hyperlipidemic men and women (total cholesterol >240 mg/dL [6.2 mmol/L], low-density lipoprotein cholesterol >190 mg/dL [4.9 mmol/L], triglycerides <500 mg/dL [5.6 mmol/L]) were separated in two groups. One group consisted of 15 subjects on atenolol therapy (50 mg daily), and the other group included 15 subjects on nebivolol therapy (5 mg daily). After 12 weeks of (-blocker therapy, pravastatin (40 mg daily) was added in both groups for another 12 weeks. Atenolol significantly increased triglyceride levels by 19% (P = .05), while nebivolol showed a trend to increase high-density lipoprotein cholesterol by 8% (NS) and to decrease triglyceride levels by 5% (NS). Atenolol significantly increased lipoprotein(a) by 30% (P = .028). Fibrinogen levels were equally and not significantly decreased in both groups by 9% and 7%, respectively. Furthermore, atenolol and nebivolol decreased serum high-sensitivity C-reactive protein levels by 14% (P = .05) and 15% (P = .05), respectively. On the other hand, both atenolol and nebivolol showed a trend to increase homocysteine levels (NS) by 13% and 11%, respectively. Although uric acid levels remained the same, atenolol significantly increased the fractional excretion of uric acid by 33% (P = .03). Following nebivolol administration, glucose levels remained the same, while insulin levels were reduced by 10% and the HOMA index (fasting glucose levels multiplied by fasting insulin levels and divided by 22.5) was reduced by 20% (P = .05). There were no significant differences between the two patient groups in the measured parameters after the administration of (-blockers, except for triglycerides (P < .05) and the HOMA index (P = .05). The addition of pravastatin to all patients (n = 30) decreased total cholesterol by 21% (P < .001), low-density lipoprotein cholesterol by 28% (P < .001), apolipoprotein-B by 22% (P < .001), apolipoprotein-E by 15% (P = .014) and lipoprotein(a) levels by 12% (P = .023). Moreover, homocysteine levels and C-reactive protein were reduced by 17% (P = .05) and 43% (P = .05), respectively. We conclude that nebivolol seems to be a more appropriate therapy in hypertensive patients with hyperlipidemia and carbohydrate intolerance. Finally, the addition of pravastatin could further correct the well-established predictors of cardiovascular events.

Comparison of the Efficacy of Atorvastatin and Micronized Fenofibrate in the Treatment of Mixed Hyperlipidemia

Objective To evaluate and compare the influences of micronized fenofibrate and atorvastatin on serum lipid profile, including lipoprotein(a) levels, and on fibrinogen levels in a large group of patients with primary mixed hyperlipidemia (serum total and low-density lipoprotein cholesterol levels >240 and 160 mg/dl, respectively, and serum triglyceride level >200 mg/dl). Methods This was a 16-week, open-label, parallel-design study conducted in our lipid clinic. After a 6-week dietary baseline phase, we implemented a treatment phase, during which patients received 10 mg/day atorvastatin (n=45) or 200 mg/day micronized fenofibrate (n = 46) for 16 weeks. Patients were assigned to one of the drugs in sequential orders. Serum lipid profiles, including levels of lipoprotein(a) and fibrinogen, as well as muscle and liver enzymes, were measured during screening, and during weeks −4, −2, 0, 8, and 16 of the treatment period. Results Atorvastatin was more effective than was micronized fenofibrate at lowering levels of total and low-density lipoprotein cholesterol, whereas fenofibrate was more effective at lowering levels of triglycerides, and raising levels of high-density lipoprotein cholesterol and apolipoprotein A1. However, micronized fenofibrate could significantly decrease plasma fibrinogen levels, whereas atorvastatin evoked a small increase. Conclusion Both atorvastatin in small doses and micronized fenofibrate are effective for improving serum lipid profiles of patients with mixed hyperlipidemia. However, there are considerable differences between the two drugs concerning their influences on plasma fibrinogen levels.

Lipoprotein (a) Levels and Apolipoprotein (a) Isoform Size in Patients with Subclinical Hypothyroidism: Effect of Treatment with Levothyroxine

The increased risk for ischemic heart disease (IHD) associated with subclinical hypothyroidism (SH) has been partly attributed to dyslipidemia. There is limited information on the effect of SH on lipoprotein (a) [Lp(a)], which is considered a significant predictor of IHD. Serum Lp(a) levels are predominantly regulated by apolipoprotein [apo(a)] gene polymorphisms. The aim of our study was to evaluate the Lp(a) levels and apo(a) phenotypes in patients with SH compared to healthy controls as well as the influence of levothyroxine substitution therapy on Lp(a) values in relation to the apo(a) isoform size. Lp(a) levels were measured in 69 patients with SH before and after restoration of a euthyroid state and in 83 age- and gender-matched healthy controls. Apo(a) isoform size was determined by sodium dodecyl sulfate (SDS) agarose gel electrophoresis followed by immunoblotting and development via chemiluminescence. Patients with SH exhibited increased Lp(a) levels compared to controls (median value 10.6 mg/dL vs. 6.0 mg/dL, p = 0.003]), but this was not because of differences in the frequencies of apo(a) phenotypes. There was no association between thyrotropin (TSH) and Lp(a) levels in patients with SH. In subjects with either low (LMW; 25 patients and 28 controls) or high (HMW; 44 patients and 55 controls) molecular weight apo(a) isoforms, Lp(a) concentrations were higher in patients than in the control group (median values 26.9 mg/dL vs. 21.8 mg/dL, p = 0.02 for LMW, and 6.0 mg/dL versus 3.3 mg/dL, p < 0.001 for HMW). Levothyroxine treatment resulted in an overall reduction of Lp(a) levels (10.6 mg/dL baseline vs. 8.9 mg/dL posttreatment, p = 0.008]). This effect was mainly evident in patients with LMW apo(a) isoforms associated with high baseline Lp(a) concentrations (median values 26.9 mg/dL vs. 23.2 mg/dL pretreatment and posttreatment, respectively; p = 0.03). In conclusion, even though a causal effect of thyroid dysfunction on Lp(a) was not clearly demonstrated in patients with SH, levothyroxine treatment is beneficial, especially in patients with increased baseline Lp(a) levels and LMW apo(a) isoforms.