Decreased neointimal formation in Mac-1(-/-) mice reveals a role for inflammation in vascular repair after angioplasty

Inflammation plays an essential role in the initiation and progression of atherosclerosis, but its role in vascular repair after mechanical arterial injury (i.e., percutaneous transluminal coronary angioplasty, PTCA) is unknown. In animal models of vascular injury, leukocytes are recruited as a precursor to intimal thickening. Furthermore, markers of leukocyte activation - in particular, increased expression of the beta2-integrin Mac-1 (alphaMbeta2, or CD11b/CD18), which is responsible for firm leukocyte adhesion to platelets and fibrinogen on denuded vessels - predict restenosis after PTCA. To determine whether Mac-1-mediated leukocyte recruitment is causally related to neointimal formation, we subjected mice lacking Mac-1 to a novel form of mechanical carotid artery dilation and complete endothelial denudation. We now report that the selective absence of Mac-1 impairs transplatelet leukocyte migration into the vessel wall, reducing leukocyte accumulation over time. Diminished medial leukocyte accumulation was accompanied by markedly reduced neointimal thickening after vascular injury. These data establish a role for inflammation in neointimal thickening and suggest that leukocyte recruitment to mechanically injured arteries may prevent restenosis.

Interactions between angiotensin-I converting enzyme insertion/deletion polymorphism and response of plasma lipids and coronary atherosclerosis to treatment with fluvastatin: the lipoprotein and coronary atherosclerosis study

OBJECTIVES

Our objectives were to determine whether angiotensin-1 converting enzyme (ACE) insertion/deletion (I/D) polymorphism was associated with the severity of coronary artery disease (CAD) and its progression/regression in response to fluvastatin therapy in the Lipoprotein and Coronary Atherosclerosis Study (LCAS) population.

BACKGROUND

Genetic factors are involved in susceptibility to CAD. Angiotensin-1 converting enzyme I/D polymorphism, which accounts for half of the variance of plasma and tissue levels of ACE, has been implicated in susceptibility to CAD and myocardial infarction (MI).

METHODS

Angiotensin-1 converting enzyme genotypes were determined by polymerase chain reaction (PCR). Fasting plasma lipids were measured and quantitative coronary angiograms were obtained at baseline and 2.5 years following randomization to fluvastatin or placebo.

RESULTS

Ninety-one subjects had DD, 198 ID and 75 II genotypes. The mean blood pressure, minimum lumen diameter (MLD), number of coronary lesions and total occlusions were not significantly different at baseline or follow-up among the genotypes. There was a significant genotype-by-treatment interaction for total cholesterol (p = 0.018), low-density lipoprotein cholesterol (LDL-C) (p = 0.005) and apolipoprotein (apo) B (p = 0.045). In response to fluvastatin therapy, subjects with DD, compared with those with ID and II genotypes, had a greater reduction in total cholesterol (19% vs. 15% vs. 13%), LDL-C (31% vs. 25% vs. 21%) and apo B (23% vs. 15% vs. 12%). Definite progression was less (14%) and regression was more common (24%) in DD as compared with those with ID (32% and 17%) and II (33% and 3%) genotypes (p = 0.023). Changes in the mean MLD and lesion-specific MLD also followed the same trend.

CONCLUSIONS

Angiotensin-1 converting enzyme I/D polymorphism is associated with the response of plasma lipids and coronary atherosclerosis to treatment with fluvastatin. Subjects with DD genotype had a greater reduction in LDL-C, a higher rate of regression and a lower rate of progression of CAD.

Relative contribution of LFA-1 and Mac-1 to neutrophil adhesion and migration

To differentiate the unique and overlapping functions of LFA-1 and Mac-1, LFA-1-deficient mice were developed by targeted homologous recombination in embryonic stem cells, and neutrophil function was compared in vitro and in vivo with Mac-1-deficient, CD18-deficient, and wild-type mice. LFA-1-deficient mice exhibit leukocytosis but do not develop spontaneous infections, in contrast to CD18-deficient mice. After zymosan-activated serum stimulation, LFA-1-deficient neutrophils demonstrated activation, evidenced by up-regulation of surface Mac-1, but did not show increased adhesion to purified ICAM-1 or endothelial cells, similar to CD18-deficient neutrophils. Adhesion of Mac-1-deficient neutrophils significantly increased with stimulation, although adhesion was lower than for wild-type neutrophils. Evaluation of the strength of adhesion through LFA-1, Mac-1, and CD18 indicated a marked reduction in firm attachment, with increasing shear stress in LFA-1-deficient neutrophils, similar to CD18-deficient neutrophils, and only a modest reduction in Mac-1-deficient neutrophils. Leukocyte influx in a subcutaneous air pouch in response to TNF-alpha was reduced by 67% and 59% in LFA-1- and CD18-deficient mice but increased by 198% in Mac-1-deficient mice. Genetic deficiencies demonstrate that both LFA-1 and Mac-1 contribute to adhesion of neutrophils to endothelial cells and ICAM-1, but adhesion through LFA-1 overshadows the contribution from Mac-1. Neutrophil extravasation in response to TNF-alpha in LFA-1-deficient mice dramatically decreased, whereas neutrophil extravasation in Mac-1-deficient mice markedly increased.

Endothelial alpha 2,6-linked sialic acid inhibits VCAM-1-dependent adhesion under flow conditions

We have previously shown that costimulation of endothelial cells with IL-1 + IL-4 markedly inhibits VCAM-1-dependent adhesion under flow conditions. We hypothesized that sialic acids on the costimulated cell surfaces may contribute to the inhibition. Northern blot analyses showed that Gal beta 1-4GlcNAc alpha 2, 6-sialyltransferase (ST6N) mRNA was up-regulated in cultured HUVEC by IL-1 or IL-4 alone, but that the expression was enhanced by costimulation, whereas the level of Gal beta 1-4GlcNAc/Gal beta 1-3GalNAc alpha2,3-sialyltransferase (ST3ON) mRNA was unchanged. Removing both alpha 2,6- and alpha 2,3-linked sialic acids from IL-1 + IL-4-costimulated HUVEC by sialidase significantly increased VCAM-1-dependent adhesion, whereas removing alpha 2,3-linked sialic acid alone had no effect; adenovirus-mediated overexpression of ST6N with costimulation almost abolished the adhesion, which was reversible by sialidase. The same treatments of IL-1-stimulated HUVEC had no effect. Lectin blotting showed that VCAM-1 is decorated with alpha 2,6- but not alpha 2,3-linked sialic acids. However, overexpression of alpha 2,6-sialyltransferase did not increase alpha 2,6-linked sialic acid on VCAM-1 but did increase alpha 2,6-linked sialic acids on other proteins that remain to be identified. These results suggest that alpha 2,6-linked sialic acids on a molecule(s) inducible by costimulation with IL-1 + IL-4 but not IL-1 alone down-regulates VCAM-1-dependent adhesion under flow conditions.

Inflammation and lipid-lowering treatment

Leukocytes play a critical role in both the initial steps of atherogenesis and the late events of plaque instability and thrombosis. Leukocyte-endothelial cell adhesion molecules (CAMs) modulate the interaction between circulating leukocytes and the vessel wall. Levels of soluble CAMs are increased in patients with dyslipidemia or other risk factors, and levels can be reduced by lipid-modifying therapy. Novel markers of inflammation and atherosclerosis may be useful to identify high-risk individuals and to assess the efficacy of antiatherosclerotic therapy.

Myocardial infarction and remodeling in mice: effect of reperfusion

Anatomic and functional changes after either a permanent left anterior descending coronary artery occlusion (PO) or 2 h of occlusion followed by reperfusion (OR) in C57BL/6 mice were examined and compared with those in sham-operated mice. Both interventions generated infarcts comprising 30% of the left ventricle (LV) measured at 24 h and equivalent suppression of LV ejection velocity and filling velocity measured by Doppler ultrasound at 1 wk. Serial follow-up revealed that the ventricular ejection velocity and filling velocity returned to the levels of the sham-operated controls in the OR group at 2 wk and remained there; in contrast, PO animals continued to display suppression of both systolic and diastolic function. In contrast, ejection fractions of PO and OR animals were depressed equivalently (50% from sham-operated controls). Anatomic reconstruction of serial cross sections revealed that the percentage of the LV endocardial area overlying the ventricular scar (expansion ratio) was significantly larger in the PO group vs. the OR group (18 +/- 1.7% vs. 12 +/- 0.9%, P < 0.05). The septum that was never involved in the infarction had a significantly (P < 0.002) increased mass in PO animals (22.5 +/- 1.08 mg) vs. OR (17.8 +/- 1.10 mg) or sham control (14.8 +/- 0.99 mg) animals. Regression analysis demonstrated that the extent of septal hypertrophy correlated with LV expansion ratio. Thus late reperfusion appears to reduce the degree of infarct expansion even under circumstances in which it no longer can alter infarct size. We suggest that reperfusion promoted more effective ventricular repair, less infarct expansion, and significant recovery or preservation of ventricular function.

Reducing atherothrombotic events in high-risk patients: recent data on therapy with statins and fatty acids

Traditional treatment of atherosclerotic coronary heart disease by cardiovascular specialists, which has focused on "critical" stenoses, may be less effective in reducing morbidity and mortality than therapies that stabilize plaques and reduce thrombosis and sudden death. Recent data from clinical trials of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor (statin) therapy and modification of dietary fat composition demonstrate that both these approaches can reduce clinical events. Although revascularization therapy is effective in reducing angina caused by high-grade stenotic lesions, this therapy is incomplete because the more-numerous "smaller" plaques that typically cause clinical events remain untreated. Two recent trials suggest that statin therapy may have benefits on stabilizing plaques in high-risk patients within a year. Additional benefit may also be provided by increasing dietary consumption of monounsaturated or omega-3 polyunsaturated fatty acids. Both statin therapy and diets high in monounsaturated or omega-3 fatty acids appear to improve morbidity and mortality by modifying the underlying atherothrombotic disease process.

Lipoprotein lipase gene mutations, plasma lipid levels, progression/regression of coronary atherosclerosis, response to therapy, and future clinical events. Lipoproteins and Coronary Atherosclerosis Study

Mutations in human lipoprotein lipase (LPL) gene are potential risk factors for susceptibility to coronary artery disease (CAD). The objectives of this study were to determine the influence LPL mutations Asn291Ser and Ser447Ter on plasma lipid levels, regression and progression of CAD, clinical events rate, and response to fluvastatin therapy in the Lipoprotein and Coronary Atherosclerosis Study (LCAS) population. LCAS is a double blind, randomized, placebo-controlled study designed to test the influence of fluvastatin on progression or regression of CAD. The Asn291Ser and Ser447Ter genotypes were determined by polymerase chain reaction (PCR) and restriction enzyme digestion. Fasting plasma lipid profiles were measured and quantitative coronary angiography was performed at baseline and 2.5 years following randomization. Fatal and non-fatal cardiovascular events during the follow-up period were recorded. A total of 4% (14/363) and 18% (62/352) of the subjects had the Asn291Ser and Ser447Ter mutations, respectively. Overall, there was no statistically association between the Asn291Ser and Ser447Ter mutations and the baseline or final mean plasma levels of lipids, number of coronary lesions, total occlusions, the mean minimal lumen diameter (MLD) stenoses and the clinical events rate. However, patients with the Ser447Ter variant had a slightly higher baseline high density lipoprotein-cholesterol (HDL-C) level (46.2 +/- 12 vs 43.2 +/- 11, P = 0.057), less increase in plasma HDL levels in response to fluvastatin therapy (3 vs 11%, P = 0.056) and a higher cardiovascular events rate (23 vs 13%, P = 0.056). Thus, the Ser447Ter variant had a modest influence on plasma HDL levels and the rate of cardiovascular events. These changes were of borderline statistical significance. Neither the Ser447Ter nor the Asn291Ser mutation had a major impact on susceptibility to CAD, progression or regression of CAD, clinical events rate or response to fluvastatin therapy in LCAS population.

Effect of moderate alcohol consumption on hypertriglyceridemia: a study in the fasting state

BACKGROUND

Patients with hypertriglyceridemia (HTG) are generally advised to avoid alcohol, even though moderate alcohol consumption is cardioprotective. Alcohol increases plasma triglyceride concentration transiently in normolipidemic subjects, but whether alcohol consumption per se increases triglyceride concentrations in patients with HTG is unclear.

OBJECTIVE

To assess whether baseline fasting triglyceride concentration determines plasma triglyceride concentration after acute oral alcohol intake.

METHODS

Twelve persons with fasting triglyceride concentrations of 2.3 to 8.5 mmol/L (200-750 mg/dL) and 12 persons as a non-HTG group were enrolled. Obesity, current smoking, and history of hypertension, diabetes, or excessive alcohol use were exclusionary. Fasted subjects consumed 38 mL of ethanol in water (equivalent, 2 alcoholic drinks); blood samples were collected at baseline and at intervals thereafter for 10 hours. No less than 1 week later, the subjects consumed water alone in a control test.

RESULTS

Mean triglyceride values were 4.04+/-0.41 mmol/L (358+/-36.9 mg/dL) and 1.00+/-0.11 mmol/L (89+/-10.2 mg/dL) for the HTG and non-HTG groups, respectively. Despite similar changes with alcohol feeding in plasma ethanol, nonesterified fatty acid, and acetate concentrations, the groups differed in triglyceride response. At 6 hours (peak) compared with baseline, triglyceride concentration increased only 3% in the HTG group but 53% in the non-HTG group. The former change was not significantly different from the effect with water alone (-9.2% from baseline; P = .43), whereas the latter was (-8.0%; P = .003).

CONCLUSIONS

Acute alcohol intake alone is not an important determinant of plasma triglyceride concentration in individuals with HTG. Other factors, such as the contemporaneous consumption of fat and alcohol, known to increase triglyceride concentrations synergistically in non-HTG individuals, may be more important.

Correlation of serum triglyceride and its reduction by omega-3 fatty acids with lipid transfer activity and the neutral lipid compositions of high-density and low-density lipoproteins

Serum triglyceride (TG) and high-density lipoprotein cholesterol (HDL-C) concentrations are inversely correlated and mechanistically linked by means of lipid transfer activities. Phospholipid transfer activity (PLTA) moves phospholipids among serum lipoproteins; cholesteryl ester transfer activity (CETA), which exchanges cholesteryl esters (CE) and TG among lipoproteins, is stimulated by nonesterified fatty acids (NEFA). The aims of this study were (a) to develop a quantitative model that correlates the neutral lipid (NL = CE + TG) compositions of HDL and LDL with serum TG concentration; (b) identify the serum lipid determinants of CETA and PLTA, and; (c) identify the effects of serum TG reductions on the neutral lipid compositions of HDL and LDL, serum NEFA concentrations, and on PLTA and CETA. These aims were addressed in 40 hypertriglyceridemic subjects before and after treatment with an 85% concentrate of omega-3 fatty acids (Omacor) and in 16 untreated normolipidemic subjects. In vivo, the NL compositions of LDL and HDL were described by a mathematical model having the form of adsorption isotherms: HDL - (TG/NL) = (0.90 +/- 0.07) serum TG/(7.0 +/- 1.2 mmol/l + serum TG) and LDL - (TG/NL) = (0.65 +/- 0.08) serum TG/(4.9 +/- 1.5 mmol/l + serum TG). Reduction of serum TG was associated with reductions in HDL - (TG/NL), serum NEFA concentration, and serum CETA but not PLTA. These data suggest that both hypertriglyceridemia and the attendant elevated serum CETA but not PLTA are determinants of HDL and LDL composition and structure and that serum TG concentrations are good predictors of the NL compositions of HDL and LDL.

Influence of low HDL on progression of coronary artery disease and response to fluvastatin therapy

BACKGROUND--Patients with coronary artery disease (CAD) commonly have low HDL cholesterol (HDL-C) and mildly elevated LDL cholesterol (LDL-C), leading to uncertainty as to whether the appropriate goal of therapy should be lowering LDL-C or raising HDL-C. METHODS AND RESULTS--Patients in the Lipoprotein and Coronary Atherosclerosis Study (LCAS) had mildly to moderately elevated LDL-C; many also had low HDL-C, providing an opportunity to compare angiographic progression and the benefits of the HMG-CoA reductase inhibitor fluvastatin in patients with low versus patients with higher HDL-C. Of the 339 patients with biochemical and angiographic data, 68 had baseline HDL-C <0.91 mmol/L (35 mg/dL), mean 0.82+/-0.06 mmol/L (31. 7+/-2.2 mg/dL), versus 1.23+/-0.29 mmol/L (47.4+/-11.2 mg/dL) in patients with baseline HDL-C >/=0.91 mmol/L. Among patients on placebo, those with low HDL-C had significantly more angiographic progression than those with higher HDL-C. Fluvastatin significantly reduced progression among low-HDL-C patients: 0.065+/-0.036 mm versus 0.274+/-0.045 mm in placebo patients (P=0.0004); respective minimum lumen diameter decreases among higher-HDL-C patients were 0. 036+/-0.021 mm and 0.083+/-0.019 mm (P=0.09). The treatment effect of fluvastatin on minimum lumen diameter change was significantly greater among low-HDL-C patients than among higher-HDL-C patients (P=0.01); among low-HDL-C patients, fluvastatin patients had improved event-free survival compared with placebo patients. CONCLUSIONS--Although the predominant lipid-modifying effect of fluvastatin is to decrease LDL-C, patients with low HDL-C received the greatest angiographic and clinical benefit.

Cytokines and the microcirculation in ischemia and reperfusion

The intense inflammatory reaction following reperfusion of the infarcted myocardium has been implicated as a factor in extension of injury. However, this inflammatory reaction is also critical to tissue repair. The cellular responses that mediate these functions are orchestrated by sequential induction and/or release of cytokines resulting in a closely regulated cytokine cascade. This paper reviews research on these cytokine cascades, their cellular origin, and factors which control the cellular response to their presence. Factors examined include leukotaxis, phenotypic transition of leukocytes, adhesion molecule induction and the role of cytokines in tissue repair and scar formation.

Low-density lipoproteins and risk for coronary artery disease

Based on the established relation between low-density lipoprotein (LDL) cholesterol and coronary artery disease (CAD), the treatment guidelines of the US National Cholesterol Education Program (NCEP) focus on LDL cholesterol reduction for primary and secondary prevention of CAD events. Abundant clinical trial evidence supports the importance of LDL cholesterol-lowering in decreasing CAD risk, both in angiographic trials, which measure CAD progression, and in trials with morbidity and mortality endpoints. The LDL cholesterol targets in the guidelines remain important treatment goals, and ongoing trials should answer questions of whether further reduction in LDL cholesterol will provide much additional benefit. Even in trials of statin therapy, in which substantial reductions of LDL cholesterol have been obtained, statins decrease (by 23-37%) but do not entirely eliminate events, suggesting that lipid parameters besides LDL cholesterol, such as high-density lipoprotein (HDL) cholesterol, triglyceride, lipoprotein(a), and LDL particle size and susceptibility to oxidation, as well as other risk factors, influence CAD risk. Unfortunately, at present, the majority of high-risk patients are not receiving either diet or drug therapy. Systematic screening to identify high-risk patients and methodical follow-up to implement diet, lifestyle modification, and drug therapy to lower LDL cholesterol, as provided for in the NCEP guidelines, should lead to significant benefits in the prevention of CAD events.

Maximizing the cost-effectiveness of lipid-lowering therapy

Cardiovascular disease, including coronary heart disease, is the leading cause of death both in men and in women in the United States. The purpose of this review is to describe the effectiveness of lipid-lowering therapy in reducing cardiovascular morbidity and mortality, which has recently been extended to patients with mild to moderate hypercholesterolemia, and the cost of providing therapy, which would be prohibitive if all persons with hypercholesterolemia received treatment. Cost-effectiveness analysis provides a rational means of allocating limited health care resources by allowing the comparison of the costs of lipid-lowering therapy, in particular, therapy with beta-hydroxy-beta-methylglutaryl-CoA (coenzyme A) reductase inhibitors (statins), with the costs of atherosclerosis that could be prevented by lowering cholesterol. To extend the benefits of treatment to the large number of persons not receiving therapy, we need to implement more cost-effective treatment by improving risk assessment, increasing treatment effectiveness, and reducing the cost of therapy.

Clinical trial endpoints: angiograms, events, and plaque instability

Clinical trials provide evidence on methods for risk assessment of coronary artery disease and on interventions used to decrease risk. Plaque rupture, which leads to either progression of coronary artery disease or myocardial infarction, is the critical biologic event in the pathophysiology of atherothrombosis that leads to morbidity and mortality. Trials with endpoints of myocardial infarction and death provide direct information on the effect of intervention on morbidity and mortality, but these trials require extremely large sample sizes and long duration. To obtain clinical information more quickly and with fewer patients, investigators have conducted trials using surrogate endpoints that examine the effect of treatment on the underlying disease process through measures of atherosclerotic lesion progression and/or regression and new lesion development. Coronary angiography studies have consistently shown that lipid-modifying therapy decreases coronary artery disease progression. The correlation between rate of progression of coronary artery disease and clinical coronary events such as myocardial infarction and coronary death may be explained by the relation of both to the biologic process of plaque rupture and thrombosis.

Defining specific goals of therapy in treating dyslipidemia in the patient with low high-density lipoprotein cholesterol

Because patients with low high-density lipoprotein (HDL) cholesterol (HDL-C) are at high risk for clinical coronary artery disease (CAD) events, these patients require aggressive treatment with lifestyle modifications-increased exercise, smoking cessation, and weight loss in overweight patients-and available pharmacological agents. Drugs that raise HDL-C include nicotinic acid, fibric acid derivatives, estrogens, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins), alpha-blockers, and alcohol. However, all agents that increase HDL-C may not have the same clinical benefit, just as, as shown in genetic studies in humans and mice, genetic causes of high HDL-C do not always protect against CAD, nor do genetic causes of low HDL-C always increase risk for CAD. Better understanding of the complexities of HDL metabolism and the mechanisms by which HDL protects against CAD is needed to enable the development of new therapeutic strategies--novel drugs or gene delivery systems--to increase HDL-C and reduce CAD events. The statins are the agents with the greatest evidence for slowing progression of CAD and reducing clinical events in patients with low HDL-C, but additional research is needed to determine the potential benefits of additional interventions that increase HDL-C, including combination therapy, which may provide greater improvements in the entire lipid profile.

Stem cell factor induction is associated with mast cell accumulation after canine myocardial ischemia and reperfusion

BACKGROUND

Myocardial infarction is associated with an intense inflammatory reaction leading to healing and scar formation. Because mast cells are a significant source of fibrogenic factors, we investigated mast cell accumulation and regulation of stem cell factor (SCF), a potent growth and tactic factor for mast cells, in the healing myocardium.

METHODS AND RESULTS

Using a canine model of myocardial ischemia and reperfusion, we demonstrated a striking increase of mast cell numbers during the healing phase of a myocardial infarction. Mast cell numbers started increasing after 72 hours of reperfusion, showing maximum accumulation in areas of collagen deposition (12.0+/-2.6-fold increase; P<0.01) and proliferating cell nuclear antigen (PCNA) expression. The majority of proliferating cells were identified as alpha-smooth muscle actin-positive myofibroblasts or factor VIII-positive endothelial cells. Mast cells did not appear to proliferate. Using a nuclease protection assay, we demonstrated induction of SCF mRNA within 72 hours of reperfusion. Immunohistochemical studies demonstrated that a subset of macrophages was the source of SCF immunoreactivity in the infarcted myocardium. SCF protein was not found in endothelial cells and myofibroblasts. Intravascular tryptase-positive, FITC-avidin-positive, CD11b-negative mast cell precursors were noted in the area of healing and in the cardiac lymph after 48 to 72 hours of reperfusion.

CONCLUSIONS

Mast cells increase in number in areas of collagen deposition and PCNA expression after myocardial ischemia. The data provide evidence of mast cell precursor infiltration into the areas of cellular injury. SCF is induced in a subset of macrophages infiltrating the healing myocardium. We suggest an important role for SCF in promoting chemotaxis and growth of mast cell precursors in the healing heart.

Current thinking in lipid lowering

In addition to elevated low-density lipoprotein (LDL) cholesterol, which has been conclusively proven to play a critical role in atherogenesis and coronary artery disease (CAD), other lipoprotein abnormalities are associated with CAD, such as reduced high-density lipoprotein (HDL) cholesterol; increased triglyceride-rich lipoproteins (very low density and intermediate-density lipoproteins); increased lipoprotein(a); small, dense LDL; and LDL with increased susceptibility to oxidation. Other, nonlipid factors such as homocysteine, fibrinogen, C-reactive protein, and soluble cell adhesion molecules may also have a role in risk stratification. The present US treatment guidelines, which focus on LDL cholesterol, stratify risk assessment and intensity of treatment by the presence of CAD; therefore, noninvasive imaging techniques such as ultrafast computed tomography and positron-emission tomography (PET) of the heart, which enable early detection of CAD, are useful in risk assessment. Because the influence of risk factors depends on their severity and combination, global risk assessment provides a necessary guide to the appropriate intensity of treatment. Agents are available that reduce LDL cholesterol and triglyceride and increase HDL cholesterol; although lipoprotein(a), LDL particle size, LDL oxidation, and homocysteine can also be altered, the clinical effects of such alterations are not known. Combination therapy that simultaneously improves multiple components of the lipid profile may provide additional benefit compared with monotherapy. To provide cost-effective treatment to the most patients, high-risk patients must be identified through systematic screening. Then each patient should be treated with the most cost-effective agent(s) that will enable achievement of the lipid levels recommended in the guidelines.

Soluble cell adhesion molecules in hypertriglyceridemia and potential significance on monocyte adhesion

Hypertriglyceridemia may contribute to the development of atherosclerosis by increasing expression of cell adhesion molecules (CAMs). Although the cellular expression of CAMs is difficult to assess clinically, soluble forms of CAMs (sCAMs) are present in the circulation and may serve as markers for CAMs. In this study, we examined the association between sCAMs and other risk factors occurring with hypertriglyceridemia, the effect of triglyceride reduction on sCAM levels, and the role of soluble vascular cell adhesion molecule-1 (sVCAM-1) in monocyte adhesion in vitro. Compared with normal control subjects (n=20), patients with hypertriglyceridemia and low HDL (n=39) had significantly increased levels of soluble intercellular adhesion molecule-1 (sICAM-1) (316+/-28.8 versus 225+/-16.6 ng/mL), sVCAM-1 (743+/-52.2 versus 522+/-43.6 ng/mL), and soluble E-selectin (83+/-5.9 versus 49+/-3.6 ng/mL). ANCOVA showed that the higher sCAM levels in patients occurred independently of diabetes mellitus and other risk factors. In 27 patients who received purified n-3 fatty acid (Omacor) 4 g/d for > or =7 months, triglyceride level was reduced by 47+/-4.6%, sICAM-1 level was reduced by 9+/-3.4% (P=.02), and soluble E-selectin level was reduced by 16+/-3.2% (P<.0001), with the greatest reduction in diabetic patients. These results support previous in vitro data showing that disorders in triglyceride and HDL metabolism influence CAM expression and treatment with fish oils may alter vascular cell activation. In a parallel-plate flow chamber, recombinant sVCAM-1 at the concentration seen in patients significantly inhibited adhesion of monocytes to interleukin-1-stimulated cultured endothelial cells under conditions of flow by 27.5+/-7.2%. Thus, elevated sCAMs may negatively regulate monocyte adhesion.

Circulating adhesion molecules VCAM-1, ICAM-1, and E-selectin in carotid atherosclerosis and incident coronary heart disease cases: the Atherosclerosis Risk In Communities (ARIC) study

BACKGROUND

Recruitment of circulating leukocytes at sites of atherosclerosis is mediated through a family of adhesion molecules. The function of circulating forms of these adhesion molecules remains unknown, but their levels may serve as molecular markers of subclinical coronary heart disease (CHD).

METHODS AND RESULTS

To determine the ability of circulating vascular cell adhesion molecule-1 (VCAM-1), endothelial-leukocyte adhesion molecule-1 (E-selectin), and intercellular adhesion molecule-1 (ICAM-1) to serve as molecular markers of atherosclerosis and predictors of incident CHD, we studied 204 patients with incident CHD, 272 patients with carotid artery atherosclerosis (CAA), and 316 control subjects from the large, biracial Atherosclerosis Risk In Communities (ARIC) study. Levels of VCAM-1 were not significantly different among the patients with incident CHD, those with CAA, and control subjects. Higher levels of E-selectin and ICAM-1 were observed for the patients with CHD (means [ng/mL]: E-selectin, 38.4; ICAM-1, 288.7) and those with CAA (E-selectin, 41.5; ICAM-1, 283.6) compared with the control subjects (E-selectin, 32.8; ICAM-1, 244.2), but the distributions were not notably different between the patients with CHD and CAA. Results of logistic regression analyses indicated that the relationship of ICAM-1 and E-selectin with CHD and CAA was independent of other known CHD risk factors and was most pronounced in the highest quartile. The odds of CHD and CAA were 5.53 (95% CI, 2.51-12.21) and 2.64 (95% CI, 1.40-5.01), respectively, for those with levels of ICAM-1 in the highest quartile compared with those in the lowest quartile. Odds of CAA were 2.03 (95% CI, 1.14-3.62) for those with levels of E-selectin in the highest quartile compared with those in the lowest quartile.

CONCLUSIONS

These data indicate that plasma levels of ICAM-1 and E-selectin may serve as molecular markers for atherosclerosis and the development of CHD.

Phagocytes in ischemia injury

We are now developing the means to evaluate components of this inflammatory response that may facilitate healing. A key event in the change in the inflammatory response is the development of a cytokine cascade that promotes phenotypic changes in the infiltrating leukocytes, which endow them with the ability to promote fibroblast proliferation and collagen deposition, the hallmarks of healing.

Effects of lipid lowering therapy on progression of coronary and carotid artery disease

Recent data have extended the benefit of lipid lowering therapy to patients with only mildly to moderately elevated LDL-cholesterol, which is typical of patients with coronary artery disease. Meta-analysis of clinical trials of statin therapy with similar sample sizes indicated that the LDL-cholesterol level on treatment was as good a predictor of angiographic benefit as was the percentage reduction in LDL-cholesterol. We review evidence that management of triglyceride-rich lipoproteins, HDL, fibrinogen, lipoprotein particle size, LDL-oxidation, and lipoprotein (a) may also favorably influence atherosclerotic progression. Angiographic and arterial ultrasound trials of lipid lowering therapy have demonstrated benefits on disease progression that are consistent with benefits on myocardial infarction, stroke, and death reported in larger, lengthier trials.

Effects of fluvastatin on coronary atherosclerosis in patients with mild to moderate cholesterol elevations (Lipoprotein and Coronary Atherosclerosis Study [LCAS])

Despite the potential for reduced morbidity and mortality, aggressive intervention against mild to moderate hypercholesterolemia in patients with coronary heart disease (CHD) remains controversial and infrequently practiced. Eligible patients in the 2.5-year Lipoprotein and Coronary Atherosclerosis Study were men and women aged 35 to 75 years with angiographic CHD and mean low-density lipoprotein (LDL) cholesterol of 115 to 190 mg/dl despite diet. Patients (n = 429; 19% women) were randomized to fluvastatin 20 mg twice daily or placebo. One fourth of patients were also assigned open-label adjunctive cholestyramine up to 12 g/day because prerandomization LDL cholesterol remained > or = 160 mg/dl. The primary end point, assessed by quantitative coronary angiography, was within-patient per-lesion change in minimum lumen diameter (MLD) of qualifying lesions. Across 2.5 years, mean LDL cholesterol was reduced by 23.9% in all fluvastatin patients (+/- cholestyramine) (146 to 111 mg/dl) and by 22.5% in the fluvastatin only subgroup (137 to 106 mg/dl). Primary end point analysis (340 patients) showed significantly less lesion progression in all fluvastatin versus all placebo patients, deltaMLD -0.028 versus -0.100 mm (p <0.01), and for fluvastatin alone versus placebo alone, deltaMLD -0.024 versus -0.094 mm (p <0.02). A consistent angiographic benefit with treatment was seen whether baseline LDL cholesterol was above or below 160 or 130 mg/dl. Beneficial trends with treatment were also consistently seen in clinical event rates but were not statistically significant. Thus, lipid lowering by fluvastatin in patients with mildly to moderately elevated LDL cholesterol significantly slowed CHD progression.