The course of vascular risk factors and the occurrence of vascular events in patients with symptomatic peripheral arterial disease

BACKGROUND

Previous studies have documented an undertreatment of vascular risk factors, and patients with symptomatic peripheral arterial disease (PAD) are at increased risk of recurrent vascular events. We examined which baseline variables are related to future vascular events, investigated the course of vascular risk factors, and compared the number of vascular risk factors at baseline and at follow-up to determine whether risk factor management could be further improved.

METHODS

This study involved 461 patients with Fontaine classification II to IV who were enrolled in the SMART study (Second Manifestations of ARTerial disease) from September 1996 to December 2000. Patients underwent a standardized screening program for risk factors and were invited for a follow-up measurement during September 2003 to March 2005, after a mean follow-up of 5.5 years (SD, 1.3 years). In the interim period between baseline and follow-up measurement, patients received usual care. During follow-up, vascular events (mortality, ischemic stroke, and myocardial infarction) and PAD-related events (vascular surgery, interventions, and amputations) were documented in detail.

RESULTS

In 2739 person-years of follow-up, 91 vascular events occurred, resulting in a 29.1% (95% confidence interval [CI], 22.8%-35.4%) cumulative incidence proportion of recurrent vascular events. Older age, increased homocysteine levels, impaired renal function, and a history of coronary heart disease at baseline were related to an increased risk of new vascular events. Of the 461 patients, 108 patients died, 20 patients were lost to follow-up, and 333 patients were eligible for follow-up measurement, in which 221 (66%) patients wished to participate. In 8 of the 221 patients, a nonfatal vascular event occurred during follow-up. The prevalence of hypertension increased from 51% to 70% (95% CI, 10%-28%), the prevalence of obesity increased from 54% to 67% (95% CI, 3%-21%), and the prevalence of diabetes mellitus increased from 8% to 16% (95% CI, 2%-14%). At follow-up, fewer patients were current smokers (59% to 37%; 95% CI, -13% to -31%), and fewer patients had increased lipid levels (96% to 73%; 95% CI, -29% to -16%). Medication use increased in all drug categories during follow-up.

CONCLUSIONS

Age, increased homocysteine levels, impaired renal function, and a history of coronary heart disease were independent risk factors for vascular events in patients with symptomatic PAD. The prevalence of most risk factors, except for smoking and hyperlipidemia, increased over a 5.5-year period even though medication use increased over the same period.

The metabolic syndrome: metabolic changes with vascular consequences

Despite criticism regarding its clinical relevance, the concept of the metabolic syndrome improves our understanding of both the pathophysiology of insulin resistance and its associated metabolic changes and vascular consequences. Free fatty acids (FFA) and tumour necrosis factor-alpha (TNF-alpha) play prominent roles in the development of insulin resistance by impairing the intracellular insulin signalling transduction pathway. Obesity is an independent risk factor for cardiovascular disease and strongly related to insulin resistance. In case of obesity, FFAs and TNF-alpha are produced in abundance by adipocytes, whereas the production of adiponectin, an anti-inflammatory adipokine, is reduced. This imbalanced production of pro- and anti-inflammatory adipokines, as observed in adipocyte dysfunction, is thought to be the driving force behind insulin resistance. The role of several recently discovered adipokines such as resistin, visfatin and retinol-binding protein (RBP)-4 in the pathogenesis of insulin resistance is increasingly understood. Insulin resistance induces several metabolic changes, including hyperglycaemia, dyslipidaemia and hypertension, all leading to increased cardiovascular risk. In addition, the dysfunctional adipocyte, reflected largely by low adiponectin levels and a high TNF-alpha concentration, directly influences the vascular endothelium, causing endothelial dysfunction and atherosclerosis. Adipocyte dysfunction could therefore be regarded as the common antecedent of both insulin resistance and atherosclerosis and functions as the link between obesity and cardiovascular disease. Targeting the dysfunctional adipocyte may reduce the risk for both cardiovascular disease and the development of type 2 diabetes. Although lifestyle intervention remains the cornerstone of therapy in improving insulin sensitivity and its associated metabolic changes, medical treatment might prove to be important as well.

Iron enhances endothelial cell activation in response to Cytomegalovirus or Chlamydia pneumoniae infection

BACKGROUND

Chronic inflammation has been implemented in the pathogenesis of inflammatory diseases like atherosclerosis. Several pathogens like Chlamydia pneumoniae (Cp) and cytomegalovirus (CMV) result in inflammation and thereby are potentially artherogenic. Those infections could trigger endothelial activation, the starting point of the atherogenic inflammatory cascade. Considering the role of iron in a wide range of infection processes, the presence of iron may complicate infection-mediated endothelial activation.

MATERIALS AND METHODS

Endothelial intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and endothelial selectin (E-selectin) expression were measured using flow cytometry, as an indication of endothelial activation. Cytotoxicity was monitored using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Immunostaining was applied to measure Cp and CMV infectivity to endothelial cells.

RESULTS

An increased number of infected endothelial cells in a monolayer population leads to a raised expression of adhesion molecules of the whole cell population, suggesting paracrine interactions. Iron additively up-regulated Cp-induced VCAM-1 expression, whereas synergistically potentiated Cp-induced ICAM-1 expression. Together with CMV, iron also enhanced ICAM-1 and VCAM-1 expression. These iron effects were observed without modulation of the initial infectivity of both microorganisms. Moreover, the effects of iron could be reversed by intracellular iron chelation or radical scavenging, conforming modulating effects of iron on endothelial activation after infections.

CONCLUSIONS

Endothelial response towards chronic infections depends on intracellular iron levels. Iron status in populations positive for Cp or CMV infections should be considered as a potential determinant for the development of atherosclerosis.

Infection induced inflammation is associated with erectile dysfunction in men with diabetes

BACKGROUND

In diabetic patients with erectile dysfunction, endothelial dysfunction is a major underlying cause. Infection-induced inflammation may be associated with endothelial dysfunction. The goal of this study was to determine whether erectile dysfunction in patients with diabetes is associated with infections of Chlamydia pneumoniae or cytomegalovirus and/or with low-grade inflammation.

MATERIALS AND METHODS

Diabetic patients, 57 with and 33 without erectile dysfunction, were enrolled in a case-control study. Both groups of patients consists of type 1 and type 2 diabetics. Serum antibodies against cytomegalovirus and C. pneumoniae and markers of inflammation, including high-sensitivity C-reactive protein and fibrinogen, were measured.

RESULTS

Adjusted odds ratios for erectile dysfunction in cytomegalovirus IgG, C. pneumoniae IgG and C. pneumoniae IgA seropositive men were 2.4 (95%CI; 1.0-6.0), 3.0 (95%CI; 1.2-8.1) and 1.8 (95%CI; 0.7-4.6), respectively. Odds ratios for the highest tertiles of high-sensitivity C-reactive protein and fibrinogen concentrations compared to the lowest tertile were 4.3 (95%CI; 1.4-13.1) and 6.6 (95%CI; 2.1-21.2), respectively.

CONCLUSION

Elevated high-sensitivity C-reactive protein or fibrinogen serum levels and infection with cytomegalovirus or C. pneumoniae were associated with erectile dysfunction in diabetes. The relation between cytomegalovirus and erectile dysfunction is markedly present in patients with elevated high-sensitivity C-reactive protein and fibrinogen levels, suggesting a modifying effect by the inflammation.

TNF-alpha induces endothelial dysfunction in diabetic adults, an effect reversible by the PPAR-gamma agonist pioglitazone

AIMS

Inflammation contributes to the pathogenesis of cardiovascular disease. Tumour necrosis factor (TNF)-alpha, in particular, is a key mediator of inflammation and vascular dysfunction and progression of atherosclerotic disease. Pioglitazone, a peroxisome proliferator-activated receptor-gamma agonist, not only improves insulin sensitivity, but may also have anti-inflammatory effects. The aims of this study were to investigate the acute effects of local intra-arterial infusion with low-dose TNF-alpha on resistance vessel endothelial function in type 2 diabetes and to determine whether short-term pioglitazone treatment protects against vascular dysfunction induced by this inflammatory stimulus.

METHODS AND RESULTS

A randomized, parallel, placebo-controlled, double blind trial with 30 mg pioglitazone once daily for 4 weeks was performed in 16 male patients with recently diagnosed type 2 diabetes. Forearm plethysmography (FBF) was used to evaluate the effect on resistance vessel responses of intra-arterial administration of serotonin (NO-dependent vasodilation) and nitroprusside (endothelium-independent vasodilation) followed by another FBF-measurement during the second hour of intra-arterial infusion with TNF-alpha (10 ng/100 mL forearm volume/min for 2 h). Endothelial-dependent FBF of type 2 diabetic patients was significantly impaired (25.4%) by intra-arterial TNF-alpha infusion (P = 0.01), whereas nitroprusside-induced vasodilation did not change. Treatment with pioglitazone for 4 weeks completely blocked TNF-alpha-induced impairment of endothelial-dependent FBF compared with placebo. No significant changes in plasma concentrations of TNF-alpha, interleukin-6, soluble TNF-alpha-receptors, or CD40L were observed.

CONCLUSION

Pioglitazone treatment can convey direct protection against cytokine (TNF-alpha)-induced endothelial dysfunction in humans with an increased cardiovascular risk due to type 2 diabetes.

Self-efficacy in patients with clinical manifestations of vascular diseases

OBJECTIVE

Patients with established cardiovascular disease are at high risk of developing new vascular events or death. This risk can be reduced by lifelong treatment of risk factors and by permanent changes in lifestyle. Self-efficacy is important for achieving behavior change by self-management. The self-efficacy of different vascular risk factors subgroups in patients with clinical manifestations of atherosclerotic vascular diseases was investigated.

METHODS

From January 2001 to September 2003, 192 patients with recently established clinically manifest atherosclerotic disease with > or = 2 modifiable vascular risk factors were selected for the study. The mean self-efficacy scores were calculated for vascular risk factors (age, sex, vascular disease, weight, diabetes mellitus, smoking behavior, hypercholesterolemia, hypertension, and hyperhomocysteinemia).

RESULTS

Diabetes, overweight, and smoking, but none of the other risk factors, were significantly associated with the level of self-efficacy in these patients.

CONCLUSIONS

Patients with vascular diseases appear to have high levels of self-efficacy regarding medication use, exercise, and controlling weight. In patients with diabetes, overweight, and in smokers, self-efficacy levels were lower.

PRACTICE IMPLICATIONS

In nursing care and research on developing self-efficacy based interventions, lower self-efficacy levels can be taken into account for specific vascular patient groups.

Screening for asymptomatic cardiovascular disease with noninvasive imaging in patients at high-risk and low-risk according to the European Guidelines on Cardiovascular Disease Prevention: the SMART study

OBJECTIVE

To assess the prevalence of atherosclerotic risk factors and to investigate the added value of noninvasive imaging in detecting asymptomatic cardiovascular diseases in patients at low risk and high risk according to the European Guidelines on Cardiovascular Disease Prevention.

METHODS

In the vascular screening program of the University Medical Center Utrecht, patients aged 18 to 79 years who had recently received a diagnosis of manifest vascular disease (coronary heart disease, cerebrovascular disease, abdominal aortic aneurysm, or peripheral arterial disease [PAD]) or had a risk factor (hypertension, hyperlipidemia, or diabetes mellitus) were assessed for atherosclerotic risk factors and (other) arterial diseases by noninvasive means. The European guidelines were applied to quantify the number of high-risk patients.

RESULTS

Eighty-eight percent of 3950 patients were considered to be at high-risk. More than 80% had hyperlipidemia, approximately 50% had hypertension, 21% had diabetes mellitus, and 31% were current smokers. An asymptomatic reduced ankle-brachial index (< or = 0.90) was most frequently observed in patients with cerebrovascular disease (21%); an asymptomatic abdominal aortic aneurysm (> or = 3.0 cm) in patients with PAD (5%) or cerebrovascular disease (5%); and an asymptomatic carotid stenosis (> or = 50%) in patients with PAD (15%). On the basis of noninvasive measurements, 73 (13%) of 545 patients initially considered as low risk were reclassified as high risk.

CONCLUSIONS

This study confirmed a high prevalence and clustering of modifiable atherosclerotic risk factors in high-risk patients. The yield of noninvasive vascular measurements was relatively low but identified a sizable number of high-risk patients. Standard screening for asymptomatic atherosclerotic disease identified a limited number of vascular abnormalities that necessitated immediate medical attention in patients already identified as high-risk patients.

Multidisciplinary Vascular Screening Program Modestly Improves the Medical Treatment of Vascular Risk Factors

PURPOSE

This study investigated whether recommendations given to the treating vascular specialist and the GP by a multidisciplinary team of vascular specialists concerning the medical treatment of risk factors, based on international guidelines, led to an increased medication use in a high-risk population.

METHODS

Data were obtained from 618 patients enrolled in the SMART study, an ongoing single-center prospective cohort study of patients referred to the University Medical Center Utrecht for atherosclerotic vascular diseases. All patients underwent a vascular screening and their physicians received recommendations concerning the medical treatment of newly detected or not yet sufficiently treated vascular risk factors. After a median follow-up of 29 months, questionnaires about medication use were sent to 618 patients; 534 (86%) questionnaires were returned. Actual use of medication was compared with medical treatment recommendation given at baseline.

RESULTS

The proportion of patients on antihypertensive medication with hypertension (> or =140/90 mmHg) and not diagnosed with coronary heart disease increased from 56% to 68% (95% confidence interval (95% CI) 2 - 23). The frequency of lipid-lowering medication use increased substantially from 47% to 69% (95% CI 17 - 28). The frequency of glucose-lowering medication use increased slightly from 11% to 14% (95% CI 1 - 7). The use of folic acid increased from 2% to 14% (95% CI 9 - 15) in patients with hyperhomocysteinaemia.

CONCLUSIONS

Medical treatment recommendations, formulated by a multidisciplinary team, led to a significant increase in medication use. The increase is marginal compared with trends in medication use without this intervention in usual care.

[The practice guideline 'Diagnosis and treatment of familial hypercholesterolaemia' of the Dutch Health Care Insurance Board]

Until 2010, the Dutch ministry of Health, Welfare and Sport will fund a nationwide project to identify the approximately 40,000 patients with familial hypercholesterolaemia (FH) in the Netherlands. The Health Care Insurance Board will coordinate the project and safeguard its quality, while the 'Stichting Opsporing Erfelijke Hypercholesterolemie' [Foundation for the Detection of Hereditary Hypercholesterolaemia], with its national network of genetic fieldworkers, will search systematically within families with assessed FH-mutations. The referral of the first suspected case of FH in a family for DNA diagnosis remains a task for GPs, internists and other clinical professionals; these will also be expected to take the responsibility for treatment. The list of diagnostic criteria of the 'Dutch Lipid Clinic Network' has recently been validated and is recommended as a decision-tool for initiating DNA diagnosis. After confirmation of the DNA diagnosis, the plasma level of LDL-cholesterol remains the main criterion for pharmacotherapy; treatment with hypocholesterolaemic agents is recommended at levels above 2.5 mmol/l.

Short-term pioglitazone treatment improves vascular function irrespective of metabolic changes in patients with type 2 diabetes

To determine whether pioglitazone influences endothelial function directly, we examined in a randomized, crossover, placebo-controlled, double-blind trial the effects of 4 weeks of pioglitazone treatment in 20 male type 2 diabetic patients. We conclude that short-term pioglitazone treatment ameliorates endothelial dysfunction in conduit arteries irrespective of significant beneficial changes in plasma levels of insulin, FFA, adiponectin, or CRP in type 2 patients with diabetes. Pioglitazone, a PPARgamma agonist, not only improves insulin resistance and glycemic control but may also have additional beneficial vascular effects in patients with type 2 diabetes. Low-grade inflammation, free fatty acids, and adiponectin may play a role in modulation of vascular function. We studied the effect of 4 weeks of pioglitazone treatment on endothelial function, metabolic changes, and C-reactive protein in patients with type 2 diabetes. A randomized, crossover, placebo-controlled, double-blind trial was performed in which pioglitazone 30 mg once daily was administered to 20 patients with type 2 diabetes on oral antihyperglycemic agents for 4 weeks. Shear stress-induced flow-mediated dilation (FMD) of the brachial artery was used as outcome parameter for vascular function. Brachial artery endothelial function was significantly increased by pioglitazone treatment compared with placebo (FMD 5.4 +/- 0.5% versus 3.1 +/- 0.5%, P = 0.001). Endothelium-independent vasodilation was not different between the 2 study periods. Pioglitazone treatment reduced insulin, FFA, and C-reactive protein concentrations compared with placebo (18.3 +/- 2.4 versus 14.8 +/- 2.1 mU/L, P = 0.03; 641 +/- 46 versus 542 +/- 33 mumol/L, P = 0.04; and 3.5 +/- 0.6 mg/L versus 2.6 +/- 0.5 mg/L, P = 0.01; respectively). A significant increase in plasma adiponectin concentration (3.95 +/- 0.57 microg/mL versus 7.59 +/- 0.95 microg/mL, P = 0.002) was also observed. No correlations were found between these metabolic changes and the improvement of conduit artery endothelial function. Short-term pioglitazone treatment ameliorates endothelial dysfunction in conduit arteries irrespective of changes in insulin, FFA, adiponectin, or CRP in type 2 patients with diabetes.

Endothelial activation and induction of monocyte adhesion by nontransferrin‐bound iron present in human sera

Nontransferrin-bound iron (NTBI) has been detected in iron overload diseases. This form of iron may exert pro-oxidant effects and modulate cellular function and inflammatory response. The present study has aimed to investigate the effects of serum NTBI on monocyte adherence to endothelium. Measured by a recently developed high-throughput fluorescence-based assay, serum NTBI was found to be higher in both homozygotes of HFE C282Y mutation of hereditary hemochromatosis (7.9+/-0.6 microM, n=9, P<0.001) and heterozygotes (4.0+/-0.5 microM, n=8, P<0.001), compared with controls (1.6+/-0.2 microM, n=21). The effects of these sera on monocyte adhesion and endothelial activation were examined. Adhesion of normal human monocytes to C282Y homozygote- and heterozygote-serum-treated human umbilical vein endothelial cells was higher (25.0+/-0.9 and 22.1+/-0.7%, respectively) compared with controls (17.6+/-0.5%, both P<0.001). For the three groups combined, the expression of adhesion molecules, ICAM-1, VCAM-1, and E-selectin, was positively correlated to NTBI levels but not to the inflammatory marker C-reactive protein. Furthermore, accumulation of intracellular labile iron and oxidative radicals within the cells due to NTBI was evidenced. Finally, counteraction of NTBI-induced endothelial activation was observed using iron chelators. These findings therefore identify a physiological function of NTBI in monocyte-endothelial interactions that may also contribute to the development of atherosclerosis and neurodegenerative diseases.

Azithromycin reduces Chlamydia pneumoniae-induced attenuation of eNOS and cGMP production by endothelial cells

BACKGROUND

Intracellular infections with cytomegalovirus (CMV) or Chlamydia pneumoniae (Cp) may play a role in the aetiology of atherosclerosis. Nitric oxide (NO) is a key regulator of endothelial function. Under pathological conditions uncoupling of endothelial nitric oxide synthase (eNOS) leads to vessel damage as a result of production of oxygen radicals instead of NO. We hypothesized that infection-induced atherosclerosis is initiated by changes in NO metabolism and may be reversed by azithromycin treatment.

METHODS

Confluent human umbilical vein endothelial cells (HUVECs) were infected with Cp or CMV. After 48 h of infection, production of eNOS, cyclic guanosine monophosphate (cGMP) and reactive oxygen species (ROS) was measured. Detection of cGMP was used as a reporter assay for the bioavailability of NO. Subsequently, Cp- and CMV-infected HUVECs were coincubated with 0.016 mg L(-1) and 1 mg L(-1) azithromycin.

RESULTS

Infection with Cp (MOI 1 and MOI 0.1) and CMV (MOI 1) caused a dose- and time-dependent reduction of eNOS production in the HUVECs: Cp MOI 1: 1141 +/- 74 pg mL(-1) (P < 0.01); Cp MOI 0.1: 3189 +/- 30 pg mL(-1) (P < 0.01); CMV: 3213 +/- 11 pg mL(-1) (P < 0.01) vs. 3868 +/- 83 pg mL(-1) for uninfected HUVECs. Chlamydia pneumoniae- but not CMV-infection also reduced cGMP-production (Cp: 0.195 +/- 0.030 pmol mL(-1) (P < 0.01); CMV: 0.371 +/- 27 pmol mL(-1) (P > 0.05) vs. 0.378 +/- 0.019 pmol mL(-1) for uninfected HUVECs). CMV-infection did not affect ROS production either, but Cp-infection reduced ROS-production by 21% (P > 0.05; Cp MOI 0.1) to 68% (P < 0.01; Cp MOI 1). Azithromycin treatment restored Cp-induced eNOS, cGMP and ROS production in a dose-dependent manner.

CONCLUSIONS

Infection with Cp in endothelial cells in vitro attenuates eNOS, cGMP and ROS production in HUVECs and azithromycin reverses Cp-induced effects on eNOS, cGMP and ROS-production. The results from our in vitro research support the role of antibiotic therapy for infection-induced atherosclerosis by indicating that azithromycin does actually improve endothelial function.

Vascular risk management through nurse-led self-management programs

In current clinical practice, adequate cardiovascular risk reduction is difficult to achieve. Treatment is primarily focused on clinical vascular disease and not on long-term risk reduction. Pertinent to success in vascular risk reduction are proper medication use, weight control, healthy food choices, smoking cessation, and physical exercise. Atherosclerotic vascular disease and its risk constitute a chronic condition, which poses specific requirements on affected patients and caregivers who should be aware of the chronicity. In patients with vascular disease, there is lack of awareness of their chronic condition because of the invisibility of most risk factors. In other patient groups with chronic illness, self-management programs were successful in achieving behavioral change. This strategy can also be useful for patients with vascular disease to adapt and adhere to an improved lifestyle. Self-management refers to the individual's ability to manage both physical and psychosocial consequences including lifestyle changes inherent to living with a chronic condition. Interventions that promote self-management are based on enhancing self-efficacy. In self-management, attention can be given to what is important and motivational to the individual patient. In this article the challenge of nursing care promoting self-management for patients with vascular risk and how this care can be applied will be explained. Nurses can play a central role in vascular risk management with a self-management approach for patients with chronic vascular disease. In vascular prevention clinics, nursing care can be delivered that includes medical treatment of vascular risks (hypertension, hypercholesterolemia, hyperglycemia, and hyperhomocystinemia) and counseling on promoting self-management (changes in diet, body weight, smoking habits, and level of exercise). Nursing interventions based on self-management promotion can provide a new and promising approach to actually achieve vascular risk reduction.

[The metabolic syndrome: a cluster of vascular risk factors]

The metabolic syndrome is a cluster of several vascular risk factors (impaired glucose metabolism, dyslipidaemia, hypertension and central adiposity). The prevalence of the metabolic syndrome is high, varying between 10 and 40% depending on age and sex. This prevalence will increase in the years to come due to the increased prevalence of overweight/obesity. To identify the metabolic syndrome, there is a readily applicable definition for daily clinical practice, i.e. the presence of three or more of the following characteristics: hyperglycaemia, hypertension, low plasma HDL cholesterol level, high plasma triglyceride level and central adiposity. The underlying pathophysiology is not fully clarified, but insulin resistance plays an important role in this syndrome. The metabolic syndrome is associated with increased cardiovascular morbidity and mortality and an increased risk for the development of diabetes mellitus type 2. In subjects with one or two components of the metabolic syndrome and in patients with manifest vascular disease, it seems advisable to be alert to the presence of the other components in order to either diagnose or exclude the metabolic syndrome. Although clinical evidence is lacking, from a pathophysiological point of view it seems reasonable to focus the treatment on reducing insulin resistance, which can be achieved by weight reduction and an increase in physical activity. Treatment of the individual risk factors may also be considered, depending on the degree of vascular risk.

Presence of the metabolic syndrome does not impair coronary collateral vessel formation in patients with documented coronary artery disease

OBJECTIVE

The metabolic syndrome confers an increased risk for cardiovascular morbidity and mortality. The presence of coronary collaterals may have beneficial effects during myocardial ischemia and may improve cardiovascular outcome in patients with coronary artery disease. Impaired collateral formation could be one of the reasons for the increased cardiovascular risk in patients with the metabolic syndrome. The aim of the present study was to determine the influence of the metabolic syndrome and insulin resistance on the presence of coronary collaterals.

RESEARCH DESIGNS AND METHODS

We conducted a cross-sectional study in 227 patients referred for elective percutaneous transluminal coronary angioplasty to the University Medical Centre Utrecht. The metabolic syndrome was diagnosed according to Adult Treatment Panel III, and homeostasis model assessment of insulin resistance (HOMA-IR) and quantitative insulin sensitivity check index (QUICKI) were used to quantify insulin resistance. Coronary collaterals were graded with Rentrop's classification. Rentrop grade >/=1 indicated the presence of collaterals. Results were adjusted for age, sex, and severity of coronary artery disease.

RESULTS

A total of 103 patients (45%) were diagnosed with the metabolic syndrome. There was no association between the metabolic syndrome and the presence of coronary collateral formation (odds ratio [OR] 1.2 [95% CI 0.7-2.0]). Also, the degree of insulin resistance was not related to the presence of coronary collaterals. The OR for HOMA-IR (highest versus lowest tertile) was 0.7 (0.3-1.5) and for QUICKI (lowest versus highest tertile) 0.8 (0.4-1.6).

CONCLUSIONS

The metabolic syndrome and insulin resistance are not related to the presence of coronary collaterals in patients with documented coronary artery disease.

Intracellular Labile Iron Modulates Adhesion of Human Monocytes to Human Endothelial Cells

OBJECTIVE

Elevated iron stores and high plasma iron concentration have been linked to an increased risk of atherosclerosis. Iron may thereby affect the interaction of monocytes to endothelium, an initial event in the formation of atherosclerotic plaques.

METHODS AND RESULTS

Addition of 10 mumol/L non-transferrin-bound iron to the incubation medium caused a 2-fold increase in monocyte adhesion to human umbilical vein endothelial cells (HUVECs). A concordant increase in the expression of the following adhesion molecules was observed: vascular cell adhesion molecule-1, intercellular adhesion molecule-1, and endothelial selectin on HUVECs as well as very late antigen-4, and lymphocyte function-associated antigen-1 on monocytes. The inclusion of either deferiprone or salicylaldehyde isonicotinoylhydrazone counteracted these effects. Intracellular iron chelation by deferoxamine was completed only after 10 hours of incubation, shown by reversal of iron-quenched intracellular calcein signal, and concurrently the effects of iron were blunted. The membrane-impermeable chelator, diethylenetriamine pentaaceticacid, failed to negate iron effects, even after 48 hours of treatment. Furthermore, only membrane-permeable superoxide or hydroxyl radical scavengers were capable of preventing HUVEC activation by iron.

CONCLUSIONS

Non-transferrin-bound iron increases the level of intracellular labile iron, which promotes monocyte recruitment to endothelium and may thereby contribute to the pathogenesis of atherosclerosis. Iron-induced adhesion molecule expression was observed, and this event may involve the production of oxygen radicals.

Cytomegalovirus and Chlamydia pneumoniae as predictors for adverse events and angina pectoris after percutaneous coronary intervention

BACKGROUND

The aim of our study was to investigate the influence of prior cytomegalovirus (CMV) or Chlamydia pneumoniae (CP) infection on prognosis after percutaneous coronary intervention (PCI).

METHODS

Using the enzyme-linked immunosorbent assay technique preprocedural anti-CMV immunoglobulin G and anti-CP immunoglobulin A (CP IgA), immunoglobulin M, and immunoglobulin G antibodies were measured. Repeat anginal complaints and major adverse clinical events (MACE), including PCI, coronary artery bypass grafting, myocardial infarction, and death, were recorded at 8-month follow-up.

RESULTS

Six hundred consecutive patients were included after successful PCI. Sixty-four percent of the patients were stented. The mean age was 61.6 years, and 68.9% were male. The rate of seropositivity for CP IgA in patients with MACE as compared with patients without MACE was 50.9% versus 35.4% (P =.0276). In patients with repeat anginal complaints, CP IgA seropositivity was 41.6% versus 34.6% in patients without repeat angina (P =.1057). The negative effect of CP on prognosis was confirmed after calculating the odds ratios for MACE (1.9, 95% CI 1.1-3.3). The rates of seropositivity for anti-CMV immunoglobulin G were not significantly different between both groups, although we found an association between infectious burden and repeat angina pectoris (odds ratio 1.8, 95% CI 1.1-3.0).

CONCLUSIONS

We conclude that preprocedural seropositivity of CP IgA is a risk factor for MACE and angina pectoris after PCI. Although no such relation was found for CMV alone, the cumulative infectious burden was also related to these clinical manifestations of restenosis.

Azithromycin inhibits interleukin-6 but not fibrinogen production in hepatocytes infected with cytomegalovirus and chlamydia pneumoniae

Chlamydia pneumoniae and cytomegalovirus (CMV) have been associated with the development of atherosclerosis. Inflammatory stimuli initiate the biosynthesis of fibrinogen, interleukin (IL)-6 and plasminogen activator inhibitor (PAI)-1 in the liver. Chronic infection may perpetuate the inflammatory status. We hypothesized that infection of human hepatocytes with the intracellular pathogens C pneumoniae and CMV accelerates biosynthesis of fibrinogen, IL-6, and PAI-1 but that this biosynthesis can be reduced with the use of azithromycin. HepG2 human hepatocytes were infected with C pneumoniae and CMV in vitro in the presence of 0, 0.016, 0.125, or 1 microg/mL azithromycin. We measured IL-6, PAI-1, and fibrinogen after 24, 48, 72, and 96 hours. C pneumoniae-infected hepatocytes produce IL-6 (2667 +/- 309 pg/mL vs 137 +/- 120 pg/mL in uninfected cells after 96 hours. Incubation with 0.016 microg/mL azithromycin decreased IL-6 levels to a mean of 1516 +/- 402 pg/mL, and incubation with 0.125 and 1 microg/mL azithromycin decreased IL-6 to 871 +/- 364 and 752 +/- 403 pg/mL, respectively. C pneumoniae-induced IL-6 production was time- and dose-dependent. The interaction of C pneumoniae with azithromycin treatment was significant, indicating an inhibitory effect of azithromycin on C pneumoniae-induced IL-6 production. CMV infection did not lead to IL-6 production by hepatocytes. C pneumoniae and CMV infection did not induce any changes in PAI-1 production. Fibrinogen production was increased by CMV infection after 72 hours (838 +/- 88 ng/mL; P <.01) and after 96 hours by infection with both C pneumoniae and CMV (765 +/- 100 and 846 +/- 123 ng/mL, respectively; P <.05). Azithromycin did not suppress CMV- or C pneumoniae-induced fibrinogen production. Moreover, we could not confirm an antiinflammatory effect of azithromycin in experiments with cross-titrations of azithromycin against either IL-1 or IL-6 (P >.05). Azithromycin reduces C pneumoniae-induced IL-6 production, but not fibrinogen production, by human hepatocytes. This is a result of the antimicrobial properties of azithromycin and not a direct antiinflammatory effect.

The metabolic syndrome is associated with advanced vascular damage in patients with coronary heart disease, stroke, peripheral arterial disease or abdominal aortic aneurysm

AIMS

The metabolic syndrome is associated with an increased risk of cardiovascular disease in patients without a cardiovascular history. We investigated whether the metabolic syndrome is related to the extent of vascular damage in patients with various manifestations of vascular disease.

METHODS AND RESULTS

The study population of this cross-sectional survey consisted of 502 patients recently diagnosed with coronary heart disease (CHD), 236 with stroke, 218 with peripheral arterial disease (PAD) and 89 with abdominal aortic aneurysm (AAA). Metabolic syndrome was diagnosed according to Adult Treatment Panel III criteria. Carotid Intima Media Thickness (IMT), Ankle Brachial Pressure Index (ABPI) and albuminuria were used as non-invasive markers of vascular damage and adjusted for age and sex if appropriate. The prevalence of the metabolic syndrome in the study population was 45%. In PAD patients this was 57%; in CHD patients 40%, in stroke patients 43% and in AAA patients 45%. Patients with the metabolic syndrome had an increased mean IMT (0.98 vs 0.92mm, P-value <0.01), more often a decreased ABPI (14% vs 10%, P-value 0.06) and increased prevalence of albuminuria (20% vs 15%, P-value 0.03) compared to patients without this syndrome. An increase in the number of components of the metabolic syndrome was associated with an increase in mean IMT (P-value for trend <0.001), lower ABPI (P-value for trend <0.01) and higher prevalence albuminuria (P-value for trend <0.01).

CONCLUSION

In patients with manifest vascular disease the presence of the metabolic syndrome is associated with advanced vascular damage.

Prevalence of the metabolic syndrome in patients with coronary heart disease, cerebrovascular disease, peripheral arterial disease or abdominal aortic aneurysm

Metabolic syndrome patients are at increased risk for developing cardiovascular morbidity and mortality. The increasing prevalence of the metabolic syndrome in various asymptomatic populations has been well documented, however, limited information is available about the prevalence in manifest atherosclerotic vascular disease patients. The aim of this study is to determine the overall and gender-specific prevalence of the metabolic syndrome and its components in these patients. This cross-sectional survey of 1117 patients, aged 18-80 years, mean age 60+/-10 years, comprised patients with coronary heart disease (n=527), cerebrovascular disease (n=258), peripheral arterial disease (n=232) or abdominal aortic aneurysm (n=100). Metabolic syndrome was defined by Adult Treatment Panel III. The prevalence of the metabolic syndrome in the study population was 46%: 58% in PAD patients, 41% in CHD patients, 43% in CVD patients and 47% in AAA patients. Overall, women had a higher prevalence than men (56% versus 43%). Age did not influence the metabolic syndrome prevalence; crude odds ratios (crude OR) 1.00 (95% CI: 0.99-1.02). Our results demonstrate a high prevalence of the metabolic syndrome in patients with manifest atherosclerotic vascular disease. Screening for metabolic syndrome in patients with high risk for new vascular incidents may identify patients with even higher vascular risk and may direct anti-atherosclerotic treatment in order to prevent new vascular incidents in the same or another vascular bed.

Preprocedural serum levels of acute-phase reactants and prognosis after percutaneous coronary intervention

OBJECTIVE

In this study we evaluate the value of baseline concentrations of acute-phase reactants on prognosis after percutaneous coronary intervention (PCI).

METHODS

Blood samples were drawn immediately before PCI to measure baseline concentrations of C-reactive protein (CRP), interleukin-6 (IL-6), lipoprotein(a) (Lp(a)), and fibrinogen. Follow-up data were collected at 8 months. Repeat PCI, CABG, myocardial infarction, and death were recorded as major adverse clinical events (MACE). Furthermore the recurrence of angina pectoris was noted.

RESULTS

The study included 600 consecutive patients after a successful PCI. Sixty-four percent of the patients were stented. The mean age was 61.6 years and 68.9% were male. CRP levels were significantly higher in patients who were to have repeat angina as compared with those who were not (P=0.0322). IL-6 levels were not correlated with angina or MACE. Lp(a) and fibrinogen concentrations were both significantly related to MACE (P=0.0337 and P=0.0253, respectively).

CONCLUSION

Our study clearly supports the role of inflammation in restenosis after PCI as measured in statistically higher levels of Lp(a) and fibrinogen in patients with MACE and CRP in patients with repeat angina.

Acute-phase response of human hepatocytes after infection with Chlamydia pneumoniae and cytomegalovirus

BACKGROUND

There is increasing evidence that chronic inflammation plays a pivotal role in the development of atherosclerosis. Whether inflammation is the cause or consequence of vascular damage is unclear. Also, the source of inflammation is unknown, but may well be infection by Cytomegalovirus (CMV) or Chlamydia pneumoniae (C. pneumoniae). Infection of the liver by CMV or C. pneumoniae may induce a general inflammatory reaction contributing to accelerated atherogenesis. In this study we investigated the production of interleukin-6 (IL-6), fibrinogen and plasminogen activator inhibitor-1 (PAI-1) by hepatocytes after infection with CMV or C. pneumoniae.

METHODS

HepG2 cell monolayers were grown to confluence in 48-well tissue culture plates. Hepatocytes were infected with 50 microL or 100 microL of suspension of CMV (10(2.70) TCID50 mL(-1)) and C. pneumoniae (10(4.75) TCID50 mL(-1)). The medium of the inoculated cells was collected every 24 h, from day 1 to day 4, for determination of IL-6, PAI-1 and fibrinogen concentrations.

RESULTS

Fibrinogen production was increased significantly in a dose-dependent manner after infection with CMV (50 microL: P=0.022 and 100 microL: P<0.001) and C. pneumoniae (P=0.012). Cytomegalovirus infection resulted in an increase of IL-6 production compared with uninfected cells (P=0.048). Cytomegalovirus and C. pneumoniae infection did not result in a significantly increase of PAI-1 production by hepatocytes.

CONCLUSION

We conclude that in addition to direct vascular wall infection by C. pneumoniae and CMV, virus-related development of atherosclerosis might also be initiated by chronic liver infection and subsequent production of inflammatory and procoagulant mediators released in the circulation. This may be another pathophysiological link for the observed relation between infections and the development of atherosclerosis.

Screening for asymptomatic internal carotid artery stenosis and aneurysm of the abdominal aorta: comparing the yield between patients with manifest atherosclerosis and patients with risk factors for atherosclerosis only

OBJECTIVE

The purpose of this study was to investigate whether screening for internal carotid artery stenosis (ICAS) and aneurysm of the abdominal aorta (AAA) is indicated in patients with either manifest atherosclerotic disease or with only risk factors for atherosclerosis.

STUDY DESIGN

Data were obtained for 2274 patients enrolled in the SMART study, an ongoing single-center, prospective cohort study of patients referred to our vascular center with manifest atherosclerotic disease (peripheral atherosclerotic disease [PAD]; transient ischemic attack [TIA], stroke, or ICAS; AAA; angina pectoris; or myocardial infarction [MI]) or with only risk factors for atherosclerosis (diabetes mellitus, hypertension, hyperlipidemia). The presence of ICAS or AAA was determined with duplex scanning and ultrasonography.

RESULTS

The prevalence of ICAS 70% or greater is low in patients with risk factors for atherosclerosis only (1.8%-2.3%), intermediate in patients with angina pectoris or MI (3.1%), and highest in patients with PAD (12.5%) or AAA (8.8%). The prevalence of AAA 3 cm or larger is low in patients with risk factors for atherosclerosis only (0.4-1.6%), intermediate in patients with angina pectoris or MI (2.6%), and highest in patients with PAD (6.5%) or TIA, stroke, or ICAS (6.5%). The prevalence of AAA larger than 5 cm is low in all of the considered patient groups. The yield of screening can be optimized through selection on the basis of simple patient characteristics. In patients with PAD, selecting those with advanced age (>54 years) increased the prevalence of ICAS to 21.8%. Selecting patients with lower diastolic blood pressure (<83 mm Hg) increased the prevalence of ICAS to 17.9%. In patients with both advanced age and lower diastolic blood pressure, the prevalence of ICAS increased to 34.7%. Selecting patients with advanced age increased the prevalence of AAA 3 cm or larger to 9.6%. In patients with TIA, stroke, or ICAS, selecting those with advanced age increased the prevalence of AAA 3 cm or larger to 8.2%. Selecting patients with taller stature (>169 cm) increased the prevalence of AAA 3 cm or larger to 9.3%. In patients with advanced age and taller stature, the prevalence of AAA 3 cm or larger increased to 13.1%.

CONCLUSIONS

Screening for ICAS should be limited to patients referred with PAD or AAA, especially those with advanced age or with low diastolic blood pressure. Screening for AAA should be limited to patients referred with PAD or with TIA, stroke, or ICAS, particularly those with advanced age or tall stature. In patients referred with angina pectoris or MI and those referred with only risk factors for atherosclerosis, screening cannot be endorsed.

Meta-analysis of sero-epidemiologic studies of the relation between Chlamydia pneumoniae and atherosclerosis: does study design influence results?

BACKGROUND

The results of sero-epidemiologic studies of the relation between Chlamydia pneumoniae and atherogenesis vary considerably. A meta-analysis was performed to calculate the overall odds ratio (OR) and to identify potential sources of variability.

METHODS

The MEDLINE database was searched from January 1997 to December 2000 for studies describing the seroprevalence of IgG antibodies to C pneumoniae in relation to clinically manifest atherosclerosis. Data extracted included 1) the study design used, 2) the number of included patients, 3) the type of disease (or end point), 4) the number of control subjects, 5) the type of control subjects, 6) the follow-up duration, 7) the crude and adjusted ORs (and 95% CI), and 8) the extent of adjustment for potential confounders.

RESULTS

Thirty-eight studies were included in the meta-analysis. The overall OR was 1.6 (95% CI 1.3-2.0). The overall OR of cross-sectional case-control studies (2.0, 95% CI 1.5-2.6) was higher than that of prospective (nested) case-control studies (1.1, 95% CI 0.8-1.4). Moreover, the duration of follow-up in prospective studies was inversely related to the strength of the relation (beta = -0.04, 95% CI -0.08, -0.01). Adjustment of risk estimates for potentially confounding factors did not influence the strength of the relation.

CONCLUSIONS

The relation between C pneumoniae and clinically manifest atherosclerosis is not durable. This probably is due to a lack of causality, although results may have been influenced by the design of the component studies.

Induction of postprandial inflammatory response in adult onset growth hormone deficiency is related to plasma remnant-like particle-cholesterol concentration

Increased cardiovascular mortality due to premature atherosclerosis is a clinical feature in the adult-onset GH deficiency (AGHD) syndrome. Inflammation is a key feature in atherogenesis and may be triggered by postprandial lipoprotein remnants. We hypothesized that increased postprandial lipoprotein remnant levels in AGHD may be associated with an inflammatory response. In this case-control study, 10 AGHD patients [6 males and 4 females; age, 48 +/- 9 yr; body mass index (BMI), 26.9 +/- 2.6 kg/m(2)] and 10 healthy control subjects (matched for age, BMI, gender, baseline lipid levels, and apolipoprotein E genotype) were included. They all ingested an oral fat load. Fasting and postprandial levels of plasma remnant-like particle-cholesterol (RLP-C; 0.31 +/- 0.13 mmol/liter and 4.14 +/- 1.37 mmol/liter.h in GHD; 0.18 +/- 0.06 mmol/liter and 2.56 +/- 1.02 mmol/liter.h in controls, respectively) were significantly increased in AGHD patients compared with control subjects. The median inflammatory cytokines, IL-6 and TNF-alpha, were higher in the fasting [3.9 (range, 3.1-11.9) pg/ml and 6.8 (range, 2.5-27.6) pg/ml, respectively] and postprandial [151.7 (range, 87.0-294.3) pg/ml.24 h and 289.9 (range, 87.5-617.6) pg/ml.24 h, respectively] states in AGHD than in controls [fasting, 0.9 (range, 0.2-5.2) pg/ml and 2.8 (range, 2.5-5.7) pg/ml; and postprandial, 54.5 (range, 11.50-126.5) pg/ml.24 h and 118.3 (range, 81.2-243.1) pg/ml.24 h, respectively]. In addition, postprandial profile of RLP-C and IL-6 in AGHD and in the total group were significantly associated (r(2) = 0.44, P < 0.05; and r(2) = 0.38, P < 0.01, respectively). In conclusion, the increased postprandial RLP-C level in GHD is associated with an inflammatory response that may result in increased susceptibility for premature atherosclerosis.

Oral Anticoagulant Therapy in Patients with Peripheral Artery Disease

Patients with peripheral artery disease suffer from a high incidence of ischemic vascular complications in coronary, cerebral, and peripheral vascular beds. Reduction of atherothrombotic complications with aspirin or clopidogrel has proven to be successful. The role of oral anticoagulants in patients with symptomatic peripheral artery is limited. Randomized controlled trials comparing the effects of aspirin with oral anticoagulants are scarce. Oral anticoagulants (International Normalized Ratio = 2.5 to 4.5) are more effective than aspirin in preventing infrainguinal bypass occlusion only when venous graft material is used and the bypass is considered to be at high risk for occlusion. Whether the use of oral anticoagulants reduces all-cause morbidity and mortality is not unequivocally clear. The risk of ischemic events is reduced at the expense of an increased number of bleeding complications, which is one of the main reasons that therapy has not been widely adopted.

Novel risk factors for peripheral arterial disease in young women

PURPOSE

To investigate traditional and novel risk factors (homocysteine and C-reactive protein levels, and exposure to infections) for peripheral arterial disease in young women.

SUBJECTS AND METHODS

In a multicenter, population-based, case-control study, 212 young women (mean [+/- SD] age, 48.2 +/- 7.0 years) with peripheral arterial disease and 475 healthy control women (mean age, 45.5 +/- 8.1 years) completed a standardized questionnaire and provided blood samples. Peripheral arterial disease was angiographically confirmed if a stenotic lesion (more than 50% reduction of the lumen) was present in at least one major peripheral artery. Hyperhomocysteinemia was defined as a nonfasting plasma homocysteine level exceeding the 90th percentile of the control group. History of infectious diseases was determined by questionnaire.

RESULTS

Elevated C-reactive protein levels were associated with an increased likelihood of peripheral arterial disease (odds ratio [OR] = 3.9; 95% confidence interval [CI]: 1.8 to 8.5 for women in the third quartile; OR = 3.1; 95% CI: 1.4 to 6.8 for women in the fourth quartile; both comparisons with women in the first quartile). Hyperhomocysteinemia was not associated with a significantly increased risk of peripheral arterial disease (OR = 1.6; 95% CI: 0.9 to 3.0). A history of chickenpox, shingles, mumps, pneumonia, chronic bronchitis, peptic ulcer, or periodontitis was independently related to peripheral arterial disease, with adjusted odds ratios varying from 1.7 (95% CI: 1.0 to 3.1) for mumps to 3.4 (95% CI: 1.5 to 7.7) for peptic ulcer. The risk of peripheral arterial disease increased with the number of these infections; exposure to five or more infections increased the odds 3.7-fold (95% CI: 1.7 to 8.2). This association was not affected by the level of C-reactive protein.

CONCLUSION

Our results do not support a strong relation between homocysteine and peripheral arterial disease in young women. However, an elevated C-reactive protein level and several types of symptomatic infection were associated with peripheral arterial disease.

Procoagulant and inflammatory response of virus-infected monocytes

BACKGROUND

Monocytes play a prominent role in inflammation, coagulation and atherosclerosis by their ability to produce tissue factor (TF) and cytokines. The aim of the present study was to establish whether virus-infected monocytes initiate coagulation. In addition, the production of cytokines by monocytes may accelerate the chronic process of atherosclerosis and may contribute to coronary syndromes by eliciting plaque instability.

MATERIALS AND METHODS

Monocytes were isolated by Vacutainer(R), BD Biosciences, Alphen aan den Rijn, Netherlands and subsequent magnetic cell sorting (MACS(R), Milteny Biotec, Bergish Gladbach, Germany). Coagulation times in normal pooled plasma and Factor VII-deficient plasma were measured after infection with cytomegalovirus (CMV), Chlamydia pneumoniae (Cp) and influenza A\H1N1. Anti-TF antibodies were added to neutralize TF expressed on monocytes. Interleukins (IL) 6, 8 and 10 were measured in the supernatants.

RESULTS

Chlamydia pneumoniae- and CMV-infected monocytes decreased the clotting time by 60%, and influenza-infected monocytes by 19%, as compared to uninfected monocytes. Procoagulant activity was absent when Factor VII-deficient plasma or anti-TF antibodies were used. Monocytes produced both IL-6 and IL-8 after infection with CMV (317 pg mL-1 and 250 pg mL-1) or Cp (733 pg mL-1 and 268 pg mL-1). Similar results were obtained for influenza virus-infected monocytes, but the levels of both cytokines were 3-5-fold higher (1797 pg mL-1 and 725 pg mL-1). Interleukin-10 was not produced by infected monocytes.

CONCLUSION

The procoagulant activity of virus-infected monocytes is TF-dependent. Although influenza infection did not generate a significant reduction in clotting time, the pronounced expression of IL-6 and IL-8 may induce local and/or systemic inflammatory reactions, which may be associated with plaque rupture and atherosclerosis. The lack of production of the anti-inflammatory cytokine IL-10 may even accelerate these processes.

Metabolic and additional vascular effects of thiazolidinediones

Several cardiovascular risk factors (dyslipidaemia, hypertension, glucose intolerance, hypercoagulability, obesity, hyperinsulinaemia and low-grade inflammation) cluster in the insulin resistance syndrome. Treatment of these individual risk factors reduces cardiovascular complications. However, targeting the underlying pathophysiological mechanisms of the insulin resistance syndrome is a more rational treatment strategy to further improve cardiovascular outcome. Our understanding of the so-called cardiovascular dysmetabolic syndrome has been improved by the discovery of nuclear peroxisome proliferator-activated receptors (PPARs). PPARs are ligand-activated transcription factors belonging to the nuclear receptor superfamily. As transcription factors, PPARs regulate the expression of numerous genes and affect glycaemic control, lipid metabolism, vascular tone and inflammation. Activation of the subtype PPAR-gamma improves insulin sensitivity. Expression of PPAR-gamma is present in several cell types involved in the process of atherosclerosis. Thus, modulation of PPAR-gamma activity is an interesting therapeutic approach to reduce cardiovascular events. Thiazolidinediones are PPAR-gamma agonists and constitute a new class of pharmacological agents for the treatment of type 2 (non-insulin-dependent) diabetes mellitus. Two such compounds are currently available for clinical use: rosiglitazone and pioglitazone. Thiazolidinediones improve insulin sensitivity and glycaemic control in patients with type 2 diabetes. In addition, improvement in endothelial function, a decrease in inflammatory conditions, a decrease in plasma levels of free fatty acids and lower blood pressure have been observed, which may have important beneficial effects on the vasculature. Several questions remain to be answered about PPAR-gamma agonists, particularly with respect to the role of PPAR-gamma in vascular pathophysiology. More needs to be known about the adverse effects of thiazolidinediones, such as hepatotoxicity, increased low-density lipoprotein cholesterol levels and increased oedema. The paradox of adipocyte differentiation with weight gain concurring with the insulin-sensitising effect of thiazolidinediones is not completely understood. The decrease in blood pressure induced by thiazolidinedione treatment seems incompatible with an increase in the plasma volume, and the discrepancy between the stimulation of the expression of CD36 and the antiatherogenic effects of the thiazolidinediones also needs further explanation. Long-term clinical trials of thiazolidinediones with cardiovascular endpoints are currently in progress. In conclusion, studying the effects of thiazolidinediones may shed more light on the mechanisms involved in the insulin resistance syndrome. Furthermore, thiazolidinediones could have specific, direct effects on processes involved in the development of vascular abnormalities.

The relation between Helicobacter pylori and atherosclerosis cannot be explained by a high homocysteine concentration

BACKGROUND

Recent studies have suggested that a chronic infection with Helicobacter pylori might be an independent risk factor for atherosclerosis. However, a direct role in atherogenesis is not plausible, since the bacterium has not been isolated from atherosclerotic lesions. An indirect mechanism that could link H. pylori with atherosclerosis might be through an increase in plasma homocysteine concentration caused by deficiencies of vitamin B12 and folate in plasma.

MATERIALS AND METHODS

In 150 female patients with peripheral arterial disease (PAD) and in 412 healthy control women from a nation-wide population-based case-control study, blood samples were collected to determine the antibody titre against H. pylori and to measure plasma homocysteine, folate and vitamin B12 levels. First, the odds ratio for PAD in women with a positive antibody titre against H. pylori was calculated and adjusted for homocysteine level. Secondly, mean concentrations of vitamin B12, folate and homocysteine were compared in healthy controls with a positive or negative antibody titre against H. pylori. Thirdly, the relation between H. pylori and PAD in individuals with a normal or high homocysteine level was investigated.

RESULTS

A positive immunoglobulin G antibody titre against H. pylori was found in 42% of the PAD patients and in 27% of the controls. The age- and socio-economic-status (SES) adjusted odds ratio for PAD was 1.5 (95%CI; 1.0-2.2). Additional adjustment for homocysteine plasma concentration did not essentially change the odds ratio. Secondly, among the healthy controls, the homocysteine plasma concentration did not depend on the immunoglobulin G titre, neither did the folate plasma concentration. The concentration of vitamin B12 was slightly higher in women with a positive titre. Thirdly, H. pylori infection was a risk factor for PAD in subjects with a normal homocysteine concentration [OR 2.0 (95%CI 1.3-3.1)].

CONCLUSIONS

This study shows a relationship between a positive immunoglobulin G antibody titre against H. pylori and PAD in young women. Moreover, this study does not support the hypothesis that H. pylori infection is related to atherosclerosis via an increase in plasma homocysteine concentration.

Chlamydia pneumoniae, Helicobacter pylori and cytomegalovirus infections and the risk of peripheral arterial disease in young women

Sero-epidemiological case control studies have observed positive relations between infections with Chlamydia pneumoniae, Helicobacter pylori or cytomegalovirus (CMV) and the occurrence of coronary artery disease (CAD) and stroke. Moreover, positive relations between 'infection burden' and CAD and the role of inflammation have recently been described. However, the relations between infection, inflammation and the occurrence of peripheral arterial disease (PAD) have not been reported so far. We performed a multi-centre population-based case-control study, using serum samples of 228 young female PAD patients and 643 control women to determine IgG antibody titres and C-reactive protein. The odds ratios for PAD in women with serological evidence for infection with C. pneumoniae, H. pylori or CMV were 2.0 (95% CI; 1.3-3.1), 1.6 (95% CI; 1.1-2.2) and 1.6 (95% CI; 1.1-2.3), respectively. The cumulative number of infections was positively related to the risk of PAD; the odds ratio was 1.5 (95% CI; 1.0-2.4), 2.7 (95% CI; 1.6-4.4) and 3.5 (95% CI; 1.5-8.1) for women with one, two or three infections, respectively. This increased risk, related to the 'infection burden', was found again in the subgroup of women with a high CRP level, but not in the subgroup with a low CRP level. Infections might be a causal component in the development of PAD. The risk of PAD is not only related to a single pathogen in particular, but also to the cumulative number of infections. The positive relation between 'infection burden' and PAD was only found in women with a high CRP level, which indicates that inflammation might be involved in the process that leads to PAD.