Triglyceride-rich lipoproteins: are links with atherosclerosis mediated by a procoagulant and proinflammatory phenotype?

Cholesterol Levels of Six Fractionated Serum Lipoproteins and its Relevance to Coronary Heart Disease Risk Scores

Aim: Evaluation of serum lipoprotein profiles including triglyceride (TG)-rich lipoprotein, that is, intermediate-density lipoprotein (IDL), very low-density lipoprotein (VLDL), and chylomicron (CM) remnant is important to manage coronary heart disease (CHD) risk. The purpose of this study was to investigate CHD or cardiovascular disease (CVD) risk scores with cholesterol levels of six fractionated lipoprotein classes {high-density lipoprotein [HDL], low-density lipoprotein [LDL], IDL, VLDL, CM including CM remnant, and lipoprotein (a) [Lp (a)]} in Japanese healthy men.

Methods: The present study enrolled 161 healthy men without any medications. Lipoprotein profiles (fractionated lipoprotein cholesterol levels) were measured by anion-exchange high-performance liquid chromatography (AEX-HPLC) method and were compared with age, estimated glomerular filtration rate (eGFR), and three risk scores, that is, NIPPON DATA, Hisayama risk predicting model, and Suita score.

Results: Levels of LDL-cholesterol (C), VLDL-C, and CM-C significantly differed with age, while values of HDL-C, IDL-C, and Lp(a)-C were not different. The eGFR inversely correlated with LDL-C, IDL-C, VLDL-C, and CM-C. In a stepwise multiple logistic regression analysis, VLDL-C only correlated independently with eGFR. Three risk scores significantly correlated with CM-C.

Conclusions: These results suggested that VLDL-C concentration contributes to an increased risk at early stages of renal dysfunction, and CM-C may serve as a marker for estimating CHD risk in Japanese healthy men.

Distribution of low-density lipoprotein and high-density lipoprotein subclasses in patients with sarcoidosis

CONTEXT

Systemic inflammatory diseases are associated with proatherogenic lipoprotein profile, but there is a lack of information regarding overall distributions of lipoprotein subclasses in sarcoidosis.

OBJECTIVE

To investigate whether patients with sarcoidosis have altered distributions of plasma low-density lipoprotein (LDL) and high-density lipoprotein (HDL) particles.

DESIGN

Seventy-seven patients with biopsy-proven sarcoidosis (29 with acute and 48 with chronic sarcoidosis) treated with corticosteroids and 77 age- and sex-matched controls were included in the study. Low-density lipoprotein and HDL subclasses were determined by gradient gel electrophoresis, while inflammatory markers and lipid parameters were measured by standard laboratory methods.

RESULTS

Compared to controls, patients had fewer LDL I subclasses (P < .001), but more LDL II and III (P < .001) subclasses. This pattern was evident in both acute and chronic disease groups. Patients also had smaller HDL size (P < .001) and higher proportions of HDL 2a (P = .006) and 3a particles (P = .004). Patients with chronic sarcoidosis had smaller LDL size than those with acute disease (P = .02) and higher proportions of HDL 3a subclasses (P = .04) than controls. In acute sarcoidosis, relative proportions of LDL and HDL particles were associated with levels of inflammatory markers, whereas in chronic disease an association with concentrations of serum lipid parameters was found.

CONCLUSIONS

The obtained results demonstrate adverse lipoprotein subfraction profile in sarcoidosis with sustained alterations during disease course. Evaluation of LDL and HDL particles may be helpful in identifying patients with higher cardiovascular risk, at least for prolonged corticosteroid therapy due to chronic disease course.

Association between postprandial triglycerides and coronary artery disease detected by coronary computed tomography angiography

BACKGROUND

Studies have demonstrated the association of severe anatomical coronary artery disease (CAD) with postprandial triglycerides (TG) concentrations. Nevertheless the relationship between less severe atherosclerosis plaque burden and postprandial TG is less established.

OBJECTIVE

to study the relationship between postprandial TG and CAD detected by coronary computed tomographic angiography (CTA).

MATERIAL AND METHODS

130 patients who underwent an oral fat tolerance test were enrolled (85 with CAD detected by CTA and 45 without). Postprandial lipemia was studied by measuring TG from T0h to T6h with 2-h intervals, and analyzed the TG change over time using a longitudinal multivariable linear mixed effects model with the log normal of the TG as the primary outcome.

RESULTS

The majority of individuals with CAD had non-obstructive disease (63.3%) Patients with CAD had a slower clearance of postprandial TG change from 4 h to 6 h (p<0.05) compared to patients without CAD. These results remained significant after adjustment for fasting TG and glucose, age, gender, body mass index, and waist circumference. However, those differences did not reach statistical significance after adjustment for fasting HDL-C.

CONCLUSION

Patients with mild (<25% lumen obstruction) and moderate CAD (25-50% lumen obstruction) detected by coronary CTA had an impaired postprandial metabolism, with a delayed TG clearance, when compared to individuals with no CAD. This difference was partially explained by the lower HDL-C. Thus, though postprandial TG may contribute to the development of CAD, this association is partially related to low HDL-C.

High-Sensitivity C-Reactive Protein in Japanese Patients with Type 2 Diabetes

OBJECTIVE

To assess the relationship between high-sensitivity (HS) C-reactive protein (CRP) and metabolic syndrome (MetS) or atherosclerosis and to assess effects of strict metabolic control on the degree of inflammation and MetS in patients with type 2 diabetes.

RESEARCH METHODS AND PROCEDURES

Four hundred thirteen patients with diabetes were enrolled in the cross-sectional study. Of these 413 patients, 161 patients were further admitted for 2.4 +/- 0.4 weeks (mean +/- SD) to investigate the change in HS-CRP or other parameters under strict metabolic control.

RESULTS

Log-transformed HS-CRP value (log HS-CRP) was strongly correlated with BMI (r = 0.448, p < 0.01). Log HS-CRP was also correlated with the presence of MetS or each component of MetS. Furthermore, a positive significant trend in HS-CRP levels was shown with an increasing number of MetS components (p < 0.05). Log HS-CRP showed a significant positive correlation with carotid artery intima-media thickness (IMT) (r = 0.152, p < 0.01). In multiple step-wise regression analysis, BMI, hemoglobin A(1c), right IMT, duration of diabetes, and triglyceride were selected as explanatory variables for log HS-CRP (R2 = 0.412). Under strict metabolic control, HS-CRP was significantly (p < 0.01) lower, together with lower levels of other markers for MetS. The change in HS-CRP was significantly correlated with the change in BMI (r = 0.161, p = 0.04).

DISCUSSION

In subjects with type 2 diabetes, HS-CRP levels are related to MetS and subclinical atherosclerosis. Strict weight management and metabolic control were associated with a reduction in HS-CRP levels, and changes in HS-CRP were related to changes in weight, supporting the hypothesis that lifestyle modification reduces inflammation and the risk of CHD.

Cardiovascular risk factors in portuguese obese children and adolescents: impact of small reductions in body mass index imposed by lifestyle modifications

Objectives:

Evaluate cardiovascular risk factors in Portuguese obese children and adolescents and the long-term effects of lifestyle modifications on such risk factors.

Design:

Transversal cohort study and longitudinal study.

Setting:

University Hospital S. João and Children’s Hospital Maria Pia, Porto.

Patients/Participants:

148 obese children and adolescents [81 females (54.7%); mean age of 11.0 years] and 33 controls (sex and age matched) participated in a cross-sectional study. Sixty obese patients agreed to participate in an one year longitudinal study after medical and nutritionist appointments to improve lifestyle modification; a substantial body mass index (BMI) reduction was defined by a decrease in BMI z-score (BMI z-sc) of 0.3 or more over the studied period.

Main Outcome measures:

Lipid profile (triglycerides, cholesterol, HDLc, LDLc, lipoprotein (a), apolipoproteins A and B) and circulating levels of C-reactive protein (CRP), adiponectin, glucose, and insulin.

Results:

Compared with the lean children, obese patients demonstrated statistically significantly higher insulin resistance index [Homeostasis model assessment (HOMA)], and triglycerides, LDLc, apolipoprotein (apo) B, insulin and CRP concentrations, whereas their HDLc and apo A levels were significantly lower (cross-sectional study). In the longitudinal study (n=60), a substantial BMI reduction occurred in 17 (28.3%) obese patients which led to a significant reduction in triglycerides, cholesterol, LDLc, apo B, glucose and insulin levels and in HOMA. The ΔBMI values over the studied period correlated inversely and significantly with BMI (P<0.001) and HOMA (P=0.026) values observed at baseline. In multiple linear regression analysis, BMI at baseline remained associated to changes in BMI over the studied period (standardised Beta: -0.271, P=0.05).

Conclusion:

Our data demonstrates that small reductions in BMI-zc, imposed by lifestyle modifications in obese children and adolescents, improve the cardiovascular risk profile of such patients. Furthermore, patients with higher BMI and/or insulin resistance seem to experience a greater relative reduction in their BMI after lifestyle improvements.

Secreted dengue virus nonstructural protein NS1 is an atypical barrel-shaped high-density lipoprotein

Dengue virus (DENV) causes the major arboviral disease of the tropics, characterized in its severe forms by signs of hemorrhage and plasma leakage. DENV encodes a nonstructural glycoprotein, NS1, that associates with intracellular membranes and the cell surface. NS1 is eventually secreted as a soluble hexamer from DENV-infected cells and circulates in the bloodstream of infected patients. Extracellular NS1 has been shown to modulate the complement system and to enhance DENV infection, yet its structure and function remain essentially unknown. By combining cryoelectron microscopy analysis with a characterization of NS1 amphipathic properties, we show that the secreted NS1 hexamer forms a lipoprotein particle with an open-barrel protein shell and a prominent central channel rich in lipids. Biochemical and NMR analyses of the NS1 lipid cargo reveal the presence of triglycerides, bound at an equimolar ratio to the NS1 protomer, as well as cholesteryl esters and phospholipids, a composition evocative of the plasma lipoproteins involved in vascular homeostasis. This study suggests that DENV NS1, by mimicking or hijacking lipid metabolic pathways, contributes to endothelium dysfunction, a key feature of severe dengue disease.

Proteomic analysis of the triglyceride-rich lipoprotein-laden foam cells

In hypertriglyceridaemic individuals, atherosclerogenesis is associated with the increased concentrations of very low density lipoprotein (VLDL) and VLDL-associated remnant particles. In vitro studies have suggested that VLDL induces foam cells formation. To reveal the changes of the proteins expression in the process of foam cells formation induced by VLDL, we performed a proteomic analysis of the foam cells based on the stimulation of differentiated THP-1 cells with VLDL. Using two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis, 14 differentially expressed proteins, containing 8 up-regulated proteins and 6 down-regulated proteins were identified. The proteins are involved in energy metabolism, oxidative stress, cell growth, differentiation and apoptosis, such as adipose differentiation-related protein (ADRP), enolase, S100A11, heat shock protein 27 and so on. In addition, the expression of some selected proteins was confirmed by Western blot and RT-PCR analysis. The results suggest that VLDL not only induces lipid accumulation, but also brings about foam cells diverse characteristics by altering the expression of various proteins.

Adiponectin deficiency suppresses ABCA1 expression and ApoA-I synthesis in the liver

Plasma high density lipoprotein (HDL)-cholesterol levels are inversely correlated with the incidence of cardiovascular diseases. HDL is mainly assembled in the liver through the ATP-binding cassette transporter (ABCA1) pathway. In humans, plasma HDL-cholesterol levels are positively correlated with plasma adiponectin (APN) concentrations. Recently, we reported that APN enhanced apolipoprotein A-I (apoA-I) secretion and ABCA1 expression in HepG2 cells. In the present study, we investigated HDL assembly in APN-knockout (KO) mice. The apoA-I protein levels in plasma and liver were reduced in APN-KO mice compared with wild-type-mice. The ABCA1 expression in liver was also decreased in APN-KO mice. APN deficiency might cause the impaired HDL assembly by decreasing ABCA1 expression and apoA-I synthesis in the liver.

The entero-insular axis and adipose tissue-related factors in the prediction of weight gain in humans

Obesity has now reached epidemic proportions. Epidemiological studies in the past decades have shown that adults gain weight and adiposity from the early twenties until their sixties. In the paediatric population, growing numbers of children and adolescents put on unhealthy weight. Many environmental, socio-economical and biological determinants that predispose to weight gain have been identified thus far. The aim of the present review is to summarize the current knowledge on the role of the circulating levels of adipokines and other entero-insular hormones and biological markers of obesity to predict weight gain in humans. The review focuses on relationship between hormonal and biochemical markers (insulin, insulin-like growth factors, gastrointestinal hormones, leptin, adiponectin, resistin, inflammatory proteins and cytokines) and weight gain in prospective studies. The complex relationships displayed by these hormonal factors with future weight gain in humans are critically reviewed and integrative models are proposed. Overall, most of the studies reported to date made adjustments for baseline body mass index but failed to consider dietary intake and physical activity as confounding factors. Outstanding questions are raised and new directions for future prospective studies are proposed in order to improve our understanding of the role of biological determinants of energy balance and development of obesity in humans.

Paradoxical effects of fenofibrate and nicotinic acid in apo E-deficient mice

Atherosclerosis is a complex vascular disease initiated by abnormal accumulation of plasma lipoproteins in the subendothelial space. Elevated levels of plasma triglycerides (TG) and low-density lipoprotein (LDL)-cholesterol as well as low concentrations of high-density lipoprotein (HDL) play a causal role in the development and progression of atherosclerotic lesions. We have shown that apolipoprotein E-deficient (apo E-KO) mice have elevated triglyceride levels plus diminished HDL concentrations. Drugs such as fenofibrate and nicotinic acid are well known to reduce TG and increase HDL levels in humans. In this study, we investigated the beneficial effects of fenofibrate and niacin on lipid profile and atherogenesis in apo E-KO mice and their wild-type counterparts. Animals were fed with a cholesterol-enriched diet supplemented with fenofibrate (0.1% wt/wt, n = 8) or nicotinic acid (0.5% wt/wt, n = 8) for 14 weeks. Body weights were recorded weekly, and plasma lipid profiles were determined at 4-week intervals. The hearts and aortas were collected and fixed for histologic and morphometric evaluations of atherosclerotic lesions. Fenofibrate treatment in apo E-KO mice paradoxically increased total cholesterol and TG by 65% and 44%, respectively, and decreased HDL-cholesterol levels by 35% as compared with controls. Similar effects of fenofibrate on cholesterol levels, but not on TG concentrations, were observed in C57BL/6 mice. Fenofibrate-treated mice had lower body weight as compared with controls. Niacin had no effect on body weight gain but failed to decrease TG or to increase HDL levels in either apo E-KO mice or their wild-type counterparts. Neither fenofibrate nor niacin significantly influenced atherogenesis in apo E-KO mice as compared with controls. In conclusion, this study shows that neither niacin nor fenofibrate has beneficial lipid-modifying and antiatherosclerosis activities in mice. Identification of mechanisms underlying paradoxical effects of fenofibrate on lipoprotein metabolisms in apo E-KO mice merits further investigation.

Clinically apparent atherosclerotic disease in diabetes is associated with an increase in platelet microparticle levels

BACKGROUND

The commonest cause of mortality in patients with Type 2 diabetes is atherothrombosis, which can be related to abnormalities in the coagulation and fibrinolytic pathways, as well as in platelet function. Platelet microparticles (PMPs) may contribute to the prothrombotic state and may promote the progression of atherosclerosis. We hypothesized that PMPs are elevated in Type 2 diabetes and that patients with Type 2 diabetes and clinically apparent atherosclerosis would have the highest levels. Similarly, we hypothesized that soluble plasma P-selectin (sPsel) and CD40L (both molecules which are released by activated platelets), as well as %CD62P (P-selectin) and %CD63 positivity on platelets quantified by flow cytometry, would be highest in patients with Type 2 diabetes and clinically apparent atherosclerotic disease, and might be correlated to PMP levels.

METHODS

Venous blood was obtained from 21 Type 2 diabetic patients without atherosclerotic complications, 18 diabetic patients with clinically apparent atherosclerotic disease and 21 non-diabetic control subjects. PMPs, as well as %CD62P and %CD63 positivity on platelets, were quantified by flow cytometry. sPsel and CD40L were measured using ELISA.

RESULTS

Patients with Type 2 diabetes and clinically apparent atherosclerotic disease had the highest PMP (P=0.045) and sPsel (P=0.046) levels, compared with patients without complications (who had intermediate PMP levels) and control subjects. Control subjects had the lowest CD40L levels (P<0.001) when compared with patients with Type 2 diabetes, with no difference in sCD40L levels between the two diabetic subgroups. %CD62P and %CD63 positivity did not differ between the groups. PMP levels correlated with %CD62P positivity (P=0.026) but not to %CD63 positivity (P=0.089), sCD40L (P=0.407) or sP-sel (P=0.163); sCD40L levels did not correlate with any other marker of platelet activation.

CONCLUSION

PMPs are elevated in Type 2 diabetes. In addition, patients with clinically apparent atherosclerosis had the highest levels of PMPs and sPsel. Thus, PMPs may be a marker of symptomatic atherosclerotic vascular disease in Type 2 diabetes, and may both represent a useful risk stratification tool as well as a novel therapeutic target for anti-thrombotic drugs.

Hypertriglyceridemia, the coronary heart disease risk marker âεœsolvedâε□

Both epidemiological and intervention studies have shown that hypertriglyceridemia is a significant cardiovascular risk factor. The large variation of the triglyceride values is explained by the influence of several modifying factors, which are difficult to standardise. Therefore hypertriglyceridemia should be considered rather as risk marker, than risk factor. The measurement of the apolipoprotein CIII level, which is a more stable parameter of the triglyceride rich lipid particles, is now becoming more widespread. This parameter is also able to substitute the assessment of the small dense LDL form that has a controversial significance. The clinical benefit of reduction of triglyceride concentration and the accompanying increase of HDL cholesterol level by fibrates, in the prevention of the coronary heart disease (CHD) events, have been demonstrated in several prospective, placebo-controlled trials. The VA-HIT study, enrolling the largest number of patients, has shown that fibrates have another effect, presumably influencing the insulin resistance independently of lipid levels that is also able to reduce the CHD events.

Platelet activation in type 2 diabetes mellitus

The abnormal metabolic state that accompanies diabetes renders arteries susceptible to atherosclerosis, being capable of altering the functional properties of multiple cell types, including endothelium and platelets. In particular, an altered platelet metabolism and changes in intraplatelet signaling pathways may contribute to the pathogenesis of atherothrombotic complications of diabetes. A variety of mechanisms may be responsible for enhanced platelet aggregation. Among them, hyperglycemia may represent a causal factor for in vivo platelet activation, and may be responsible for nonenzymatic glycation of platelet glycoproteins, causing changes in their structure and conformation, as well as alterations of membrane lipid dynamics. Furthermore, hyperglycemia-induced oxidative stress is responsible for enhanced peroxidation of arachidonic acid to form biologically active isoprostanes, which represents an important biochemical link between impaired glycemic control and persistent platelet activation. Finally, increased oxidative stress is responsible for activation of transcription factors and expression of redox-sensitive genes leading to a phenotypic switch of endothelium toward an adhesive, pro-thrombotic condition, initial platelet activation, adhesion and subsequent platelet aggregate formation. All this evidence is strengthened by the results of clinical trials documenting the beneficial effects of metabolic control on platelet function, and by the finding that aspirin treatment may even be more beneficial in diabetic than in high-risk non-diabetic patients. Attention to appropriate medical management of diabetic patients will have great impact on long-term outcome in this high-risk population.

Lipolytic PPAR activation: new insights into the intersection of triglycerides and inflammation?

PURPOSE OF REVIEW

To examine connections between triglyceride metabolism and inflammation, especially as they relate to transcriptional regulation through peroxisomal proliferator activated receptors activation.

RECENT FINDINGS

Peroxisomal proliferator activated receptors, members of the steroid hormone nuclear receptor family, have been of particular interest as a mechanism through which different dietary components might control gene expression. Extensive prior work has defined the central role peroxisomal proliferator activated receptors play in many key metabolic responses, including glucose control and lipid metabolism. Emerging evidence suggests peroxisomal proliferator activated receptor activation may limit inflammation and atherosclerosis. The demonstration that certain fatty acids can activate peroxisomal proliferator activated receptors belies the potential link between nutritional components and peroxisomal proliferator activated receptor responses. Interest in this connection had been heightened by recent evidence that lipolysis in certain situations can both generate peroxisomal proliferator activated receptor ligands and limit some known inflammatory responses.

SUMMARY

Lipolytic peroxisomal proliferator activated receptor activation suggests new ways in which to reconsider triglycerides and the distal consequences of their metabolism, including the possible effects on inflammation and atherosclerosis.

Non-high-density lipoprotein cholesterol: a target of lipid-lowering in dialysis patients

BACKGROUND

The finding of an increased prevalence and levels of atherogenic lipoproteins in the context of normal plasma total and low-density lipoprotein (LDL) cholesterol (LDL-C) levels in hemodialysis (HD) patients highlights the need to look beyond the basic assessment of plasma concentrations of total cholesterol and LDL-C. Measurement of atherogenic lipoproteins (remnant lipoprotein particles [RLPs], particularly intermediate-density lipoprotein [IDL]), is not routinely performed at the present time.

METHODS

The National Cholesterol Education Program guidelines indicate that the secondary goal in persons with triglyceride levels greater than 200 mg/dL is non-high-density lipoprotein cholesterol (HDL-C). Non-HDL-C comprises all RLPs, including IDL, as well as atherogenic small dense LDL.

RESULTS

We propose, for practical reasons, that non-HDL-C be used as a primary target in HD patients when lipid-lowering therapy is indicated. However, it remains unclear whether and how effective statins are in lowering remnant particle levels in dialysis patients. Recent data show that both simvastatin and atorvastatin reduce non-HDL-C levels effectively. Atorvastatin preferentially reduces RLP levels in patients with combined hyperlipidemia.

CONCLUSION

The safety profile of statins predisposes prescription of this class of drugs to correct dyslipidemia or modulate lipoprotein particle composition in uremic patients. Whether atorvastatin influences myocardial infarction or all-cause mortality by adequately correcting dyslipidemia should be seen fairly quickly in the 1,252 dialysis patients with diabetes randomly assigned in the ongoing Die Deutsche Diabetes Dialyse study.

The influence of simvastatin on lipase and cholesterol esterase activity in the serum of men with coronary heart disease

Several studies have demonstrated that any beneficial effects of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins), of which simvastatin (Merck Sharp & Dohme) is an example, on coronary events are linked to their hypocholesterolemic properties. The in vivo effects of simvastatin treatment on lipase (GEH = glycerol ester hydrolase) and cholesterol esterase (CEase) activity in the serum of men with coronary heart disease (CHD) were examined. GEH and CEase activity in the serum of men with CHD, before simvastatin treatment, was lower than in the control subjects. In our study we have provided evidence that simvastatin increases GEH activity in a time-dependent manner, but has no effect on CEase activity. This suggests that simvastatin can directly affect acylglycerol metabolism by an increase in GEH activity and may therefore be suitable for the treatment of combined lipoprotein disorders characterized by elevation of triacylglycerols.

Therapeutic modulation of low-density lipoprotein size

Small, dense LDL particles have been linked to atherosclerosis, often in a cluster of risk factors and affecting approximately 20% of adults. Over the past year, studies confirmed that small dense LDL is an autosomal dominant trait, influenced mainly by hypertriglyceridaemia and obesity, insulin resistance and diabetes mellitus and some incompletely investigated genetic loci. Compositional and functional differences have been observed in small LDL. Evidence is emerging that lifestyle as well as pharmacological intervention can modulate LDL size, but there is no proof yet that this is of clinical benefit.

Coagulofibrinolytic assessment of effects of bezafibrate on hypertriglyceridemia in postmenopausal women

The present study investigates the effect of bezafibrate on lipid levels and coagulofibrinolytic factors. Subjects enrolled in the study included 124 postmenopausal women with hypertriglyceridemia. We examined the levels of tissue plasminogen activator (t-PA), plasminogen activator inhibitor type-1 (PAI-1), and blood coagulation factors VII and X as parameters of coagulofibrinolysis. After 12 weeks of bezafibrate therapy, mean serum triglyceride (TG) and remnant-like particle lipoprotein cholesterol (RLP-C) levels significantly decreased from baseline. Activated factor X levels decreased significantly by 11.3% (P < 0.01) and the ratio of tPA/PAI-1 (0.146+/-0.07) increased significantly by 37.7% from baseline (P < 0.05). The rates of change in activated factor VII and PAI-1 showed a significant positive correlate with the rates of change in TG and RLP-C (P = 0.001). These present findings suggest that bezafibrate improves triglyceride-rich lipoprotein metabolism and coagulofibrinolytic activity by increasing fibrinolysis in postmenopausal women with hypertriglyceridemia.

PPAR agonists as direct modulators of the vessel wall in cardiovascular disease

Successful management of cardiovascular (CV) disease and associated metabolic syndromes, such as diabetes, is a major challenge to the clinician. Reducing CV risk factors, such as abnormal lipid profiles, insulin resistance or hypertension is the foundation of such therapy. A relatively new class of therapeutic agent, activators of peroxisome proliferator-activated receptors (PPAR), is poised to make a major impact with regard to several areas of risk factor management. However, there is growing evidence that PPAR agonists may also influence the CV system directly by modulating vessel wall function. These observations suggest that additional benefit, in the treatment of CV disease, may derive not only from the ability of agents to modify risk factors but also to influence directly the cellular mechanisms of disease within the vessel wall. A precedent for this dual action comes from examination of the effects of inhibitors of HMG CoA reductase (statins), where risk factor modulation is accompanied by direct actions on the vessel wall. In this review, we summarize the evidence suggesting that PPAR agonists may directly modulate vessel wall function, and that these may parallel those effects reported recently for the statins.

The relationship of oxidized lipids to coronary artery stenosis

A total of 1200 patients with angina were cardiac catheterized establishing that 63% had 70-100% stenosis, 12% had 10-69% stenosis of one or more of their coronary arteries and 25% had microvascular angina listed as 0% stenosis. Prior to catheterization 10 ml of blood was drawn and the plasma subjected to analysis for the concentration of cholesterol, lipid peroxides (LPX), total antioxidant capacity (TAOC), fibrinogen (FB), ceruloplasmin (CP) and activation of polymorphonuclear leukocytes (PMNLs). Comparisons were made to non-smoking controls without angina. Significant differences in LPX were found between the patients with 0 and 10-69% stenosis (P<0.001), with 10-69 and 70-100% stenosis (P<0.001), and with 0 and 70-100% stenosis (P<0.001). Under 70 years of age there was a significant difference in LPX between patients with all levels of stenosis and age and sex matched controls (P<0.001). Differences in the mean plasma cholesterol concentration for different levels in the degree of stenosis were not significant, indicating that LPX provided consistent data on the severity of stenosis while the plasma cholesterol concentration did not. Compared with controls an increase in activation of PMNLs (P<0.01), an increase in concentration of both FB and CP (P<0.01) and a decrease in total antioxidant capacity were noted in the plasma of catheterized patients. In summary the concentration of oxidation products rather than the concentration of cholesterol in the plasma identified stenosis in cardiac catheterized patients.