Treatment effects on serum lipoprotein lipids, apolipoproteins and low density lipoprotein particle size and relationships of lipoprotein variables to progression of coronary artery disease in the Bezafibrate Coronary Atherosclerosis Intervention Trial (BECAIT)

High density lipoproteins and arteriosclerosis. Role of cholesterol efflux and reverse cholesterol transport

High density lipoprotein (HDL) cholesterol is an important risk factor for coronary heart disease, and HDL exerts various potentially antiatherogenic properties, including the mediation of reverse transport of cholesterol from cells of the arterial wall to the liver and steroidogenic organs. Enhancement of cholesterol efflux and of reverse cholesterol transport (RCT) is considered an important target for antiatherosclerotic drug therapy. Levels and composition of HDL subclasses in plasma are regulated by many factors, including apolipoproteins, lipolytic enzymes, lipid transfer proteins, receptors, and cellular transporters. In vitro experiments as well as genetic family and population studies and investigation of transgenic animal models have revealed that HDL cholesterol plasma levels do not necessarily reflect the efficacy and antiatherogenicity of RCT. Instead, the concentration of HDL subclasses, the mobilization of cellular lipids for efflux, and the kinetics of HDL metabolism are important determinants of RCT and the risk of atherosclerosis.

Preventing, stopping, or reversing coronary artery disease--triglyceride-rich lipoproteins and associated lipoprotein and metabolic abnormalities: the need for recognition and treatment

A substantial number of treated patients with or at high risk for coronary artery disease continue to have fatal and nonfatal coronary artery events in spite of significant reduction of elevated levels of low-density lipoprotein cholesterol. Other lipoprotein abnormalities besides an elevated level of low-density lipoprotein cholesterol contribute to risk of coronary artery disease and coronary artery events, and the predominant abnormalities that appear to explain much of this continued risk are an elevated serum triglyceride level and a low level of high-density lipoprotein cholesterol. Most patients with coronary artery disease have a mixed dyslipidemia with hypertriglyceridemia, which is associated and metabolically intertwined with other atherogenic risk factors, including the presence of triglyceride-rich lipoprotein remnants, low levels of high-density lipoprotein cholesterol, small, dense, low-density lipoprotein particles, postprandial hyperlipidemia, and a prothrombotic state. Aggressive treatment of these patients needs to focus on these other lipoprotein abnormalities as much as on low-density lipoprotein cholesterol. Combination drug therapy will usually be required. Reliable assessment of risk of coronary artery disease from lipoprotein measurements and response to therapy requires inclusion of all atherogenic lipoproteins in laboratory measurements and treatment protocols. At present this may be best accomplished by use of non-high-density lipoprotein cholesterol (total cholesterol minus high-density lipoprotein cholesterol) calculated from standard laboratory lipoprotein values. Ultimately, a more comprehensive assessment of coronary artery disease risk and appropriate therapy may include measurement of lipoprotein subclass distribution including determination of low-density lipoprotein particle concentration and sizes of the various lipoprotein particles.

Serum insulin-like growth factor-I level is independently associated with coronary artery disease progression in young male survivors of myocardial infarction: beneficial effects of bezafibrate treatment

OBJECTIVES

We investigated whether the effect of bezafibrate on progression of coronary atherosclerosis in the BEzafibrate Coronary Atherosclerosis Intervention Trial (BECAIT) was related to insulin-like growth factor (IGF)-I and glucose-insulin homeostasis.

BACKGROUND

BECAIT, the first double-blind, placebo-controlled, randomized, serial angiographic trial of a fibrate compound, demonstrated that progression of focal coronary atherosclerosis in young patients after infarction could be retarded by bezafibrate treatment.

METHODS

The treatment effects on serum concentrations of IGF-I and insulin-like growth factor binding protein (IGFBP)-1, as well as on basal and postload glucose and insulin levels, were examined, and on-trial determinations were related to the angiographic outcome measurements.

RESULTS

Bezafibrate treatment resulted in a significant reduction of serum IGF-I levels, both at two and five years, and on-trial serum IGF-I levels were directly related to changes in both minimal lumen diameter (r = 0.25, p < 0.05) and mean segment diameter (r = 0.29, p < 0.05). In contrast, none of the available indexes of insulin resistance (homeostasis model assessment estimate, basal and postload plasma insulin concentrations and serum IGFBP-1 levels) were related to the angiographic changes, nor were they significantly affected by bezafibrate treatment. Multiple stepwise regression analysis showed that the relation between on-trial serum IGF-I level and coronary artery disease (CAD) progression was independent of baseline angiographic score, age, body mass index, serum lipoprotein and plasma fibrinogen concentrations and measures of glucose-insulin homeostasis.

CONCLUSIONS

IGF-I could be implicated in the progression of premature CAD, and a reduction of serum IGF-I concentration could account partly for the effect of bezafibrate on progression of focal coronary atherosclerosis.

Pravastatin compared to bezafibrate in the treatment of dyslipidemia in insulin-treated patients with type 2 diabetes mellitus

BACKGROUND

Both HMG-CoA reductase inhibitors and fibric acid derivates are used for the treatment of dyslipidemia in Type 2 diabetes patients. The aim of this study was to compare the lipid lowering effect of 40 mg pravastatin, a HMG-CoA reductase inhibitor, and 400 mg bezafibrate, a fibric acid derivate, on serum lipids, lipoproteins and lipoprotein composition in 45 (22 men and 23 women) dyslipidemic, insulin-treated Type 2 diabetes patients.

METHOD

The study used a double-blind, cross-over design.

RESULTS

Pravastatin treatment was more effective in reducing total cholesterol, LDL-cholesterol, LDL-triglycerides, LDL-ApoB and LDL/HDL-cholesterol ratio (all p<0.001 between groups) and total/HDL-cholesterol and ApoA1/LDL-ApoB ratios (both p<0.01) and always induced a decrease in LDL-cholesterol concentrations and LDL/HDL-cholesterol ratio irrespective of baseline triglyceride concentration. Bezafibrate was more effective in increasing HDL-cholesterol (p<0.01 between groups), ApoA1 lipoprotein and decreasing triglycerides (both p<0.001 between groups) but induced an increase in LDL-cholesterol concentration particularly in patients with baseline triglyceride concentrations exceeding 2.0 mmol/l. With bezafibrate treatment the LDL-cholesterol/LDL-ApoB ratio showed a tendency to rise, suggesting a change in the LDL particle composition to a less small and dense form, while pravastatin treatment induced a decrease in this ratio suggesting a change in the LDL particle to a more dense form. With pravastatin treatment a small rise in HbA(1c) was observed.

CONCLUSION

Pravastatin treatment is superior in lowering cholesterol-enriched lipoprotein subpopulations and improving cardiovascular risk factors. Bezafibrate is more effective in raising HDL-cholesterol and alters LDL particle composition to a more favorable form.

Fibrates, dyslipoproteinaemia and cardiovascular disease

Recent epidemiological data have reaffirmed that elevated plasma triglyceride and low HDL-cholesterol levels are important risk factors for atherosclerotic vascular disease. The rationale for the clinical use of fibric acid derivatives, which are designed to correct this metabolic nexus, is now on firmer ground. The mechanism of action of fibrates on lipoprotein metabolism has recently been elucidated at the molecular level and involves the activation of peroxisome proliferator-activated receptor-alpha 1 in the liver, with the net effect of improving the plasma transport rates of several lipoproteins. Other potential anti-atherothrombotic effects include the inhibition of coagulation and enhancement of fibrinolysis, as well as the inhibition of inflammatory mediators involved in atherogenesis. These consequences probably underpin the favourable effects of fibrates seen in recent angiographic and clinical trials. Two important clinical trials on the effect of gemfibrozil (Veterans Administration-HDL-Cholesterol Intervention Trial) and bezafibrate (Bezafibrate Infarction Prevention Study) have recently been completed in subjects with elevated triglyceride, low HDL and normal or near-normal LDL-cholesterol levels. The results testify to the efficacy of these agents in decreasing the incidence of cardiovascular events, particularly in patients with multiple risk factors and plasma triglyceride levels of over 2.2 mmol/l. The findings of these trials are compared with the statin-based Air Force/Texas Coronary Atherosclerosis Prevention Study, with a recommendation that future studies in appropriately selected patients should examine the synergistic effect of the fibrate/statin combination. The absolute risk reduction in the incidence of coronary events in the Veterans Administration-HDL-Cholesterol Intervention Trial compares favourably with the statin trials. The therapeutic aspects of the efficacy and safety of fibrates are reviewed. Besides primary mixed hyperlipidaemias, particular indications for the clinical use of fibrates include type 2 diabetes, the metabolic syndrome and renal insufficiency. The St Mary's, Ealing, Northwick Park Diabetes Cardiovascular Disease Prevention Study has suggested that fibrates may decrease the incidence of coronary events in type 2 diabetes, but this hypothesis will be more extensively tested in the Diabetes Atherosclerosis Intervention Study, Fenofibrate in Event Lowering in Diabetes Study and Lipids in Diabetes Study projects. Although significant new knowledge has accrued over the past few years concerning the fundamental and clinical aspects of fibrates, the success of these agents in clinical practice depends on the availability of methods for assessing cardiovascular risk as well as on treatment guidelines, which as presently designed and recommended may be inaccurate and suboptimal.

Modification of coronary artery disease progression by cholesterol-lowering therapy: the angiographic studies

Large randomized placebo-controlled trials have demonstrated that cholesterol lowering with statin therapy reduces the incidence of adverse cardiac events. Smaller angiographic studies have shown that coronary artery disease progression can be slowed and, in some cases, reversed by cholesterol-lowering interventions. These anatomical changes, however, are small and occur too slowly to account for the early clinical benefit. Current evidence suggests that plaque stabilization is the most important mechanism, by which cholesterol-lowering therapy reduces both the incidence of adverse cardiac events and coronary artery disease progression.

Peroxisome proliferator-activated receptor alpha negatively regulates the vascular inflammatory gene response by negative cross-talk with transcription factors NF-kappaB and AP-1

Interleukin-6 (IL-6) is a pleiotropic cytokine, whose plasma levels are elevated in inflammatory diseases such as atherosclerosis. We have previously reported that peroxisome proliferator-activated receptor alpha (PPARalpha) ligands (fibrates) lower elevated plasma concentrations of IL-6 in patients with atherosclerosis and inhibit IL-1-stimulated IL-6 secretion by human aortic smooth muscle cells (SMC). Here, we show that aortic explants isolated from PPARalpha-null mice display an exacerbated response to inflammatory stimuli, such as lipopolysaccharide (LPS), as demonstrated by increased IL-6 secretion. Furthermore, fibrate treatment represses IL-6 mRNA levels in LPS-stimulated aortas of PPARalpha wild-type, but not of PPARalpha-null mice, demonstrating a role for PPARalpha in this fibrate action. In human aortic SMC, fibrates inhibit IL-1-induced IL-6 gene expression. Furthermore, activation of PPARalpha represses both c-Jun- and p65-induced transcription of the human IL-6 promoter. Transcriptional interference between PPARalpha and both c-Jun and p65 occurs reciprocally, since c-Jun and p65 also inhibit PPARalpha-mediated activation of a PPAR response element-driven promoter. This transcriptional interference occurs independent of the promoter context as demonstrated by cotransfection experiments using PPARalpha, p65, and c-Jun Gal4 chimeras. Overexpression of the transcriptional coactivator cAMP-responsive element-binding protein-binding protein (CBP) does not relieve PPARalpha-mediated transcriptional repression of p65 and c-Jun. Finally, glutathione S-transferase pull-down experiments demonstrate that PPARalpha physically interacts with c-Jun, p65, and CBP. Altogether these data indicate that fibrates inhibit the vascular inflammatory response via PPARalpha by interfering with the NF-kappaB and AP-1 transactivation capacity involving direct protein-protein interaction with p65 and c-Jun.

[Drug therapy for prognostic improvement after acute myocardial infarct]

This review article summarizes the long-term standard therapy for patients with myocardial infarction. The chronic therapy is able to significantly improve quality of life and survival of affected patients. Previous studies showed that in most western countries, the established standard therapy is not given to all patients who would benefit from chronic treatment. The essential parts of today's myocardial infarction treatment consists of effective beta-blockade, inhibition of the angiotensin-conversion enzyme, inhibition of platelet aggregation and lipid lowering agents. This article reviews the clinical benefits which may be expected from each of these therapeutic approaches. Newer, but not yet proven strategies, like blockade of the angiotensin receptor subtype 1 and treatment with antioxidative agents will be discussed.

Recent developments in the treatment of hypertriglyceridemia

Hypertriglyceridemia is now recognized as an independent risk factor of coronary artery disease (CAD). A recent secondary prevention study of CAD with a statin suggested that it may be prudent to target fasting triglycerides to less than 150 mg/dL. Secondary prevention trials of CAD with drugs acting primarily on triglycerides (fibrates) have shown that reducing triglycerides and increasing high-density lipoprotein (HDL) cholesterol, without significantly affecting low-density lipoprotein cholesterol slows down coronary artery luminal narrowing (Lopid Coronary Angiography Trial [LOCAT], Bezafibrate Coronary Atherosclerosis Intervention Trial [BECAIT], Bezafibrate Infarction Prevention [BIP]). Furthermore, Veterans Administration-HDL Intervention Trial (VA-HIT) and Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto-1 (GISSI) studies recently showed that gemfibrozil and fish oils, respectively, decreased CAD mortality in secondary prevention trials. Statins are also capable of significantly reducing high triglyceride levels. Further clinical studies are necessary to confirm in terms of mortality the beneficial effect of reducing triglycerides and increasing high-density lipoprotein cholesterol in secondary CAD prevention; whereas, in primary prevention the beneficial effect of drastically reducing triglycerides by the way of pharmacology needs to be proved.