Influence of leptin on arterial distensibility: a novel link between obesity and cardiovascular disease?

Gender influence on metabolic syndrome's effects on arterial stiffness and pressure wave reflections in treated hypertensive subjects

BACKGROUND

In hypertensive subjects, aortic stiffness, an independent predictor of cardiovascular (CV) risk, measured from pulse wave velocity (PWV), contributes to enhance augmentation index (AI), a marker of the timing and amplitude of wave reflections. Whether PWV and AI are correlated and reflect CV risk in hypertensive men and women with metabolic syndrome (MS) remains unknown.

METHODS

In a cohort of 613 (364 males) treated hypertensive subjects with and without MS (41% MS) pulse wave analysis was used to determine aortic PWV and carotid AI. CV risk was estimated from standard Framingham equations.

RESULTS

In females, but not in males, aortic PWV was higher in subjects with MS, when compared with those without MS (12.7+/-0.3m/s versus 11.1+/-0.4m/s, p<0.001). This result was independent of age and blood pressure. Only in females AI was independently related to the presence of MS; AI did not differ between subjects with or without MS, both males and females. AI did not correlate with PWV, except in males without MS. The overall CV risk was strongly associated to PWV independently of MS and gender, but AI was associated to CV risk only in males.

CONCLUSION

In treated hypertensive subjects, the effect of MS on PWV and AI is modulated by gender. The dissociation between PWV and AI observed in women with MS was due to "blunted" wave reflections. This finding is associated with the fact that PWV, but not AI, was a constant marker of CV risk in subjects with MS, whether men and women.

Insulinemia and leptinemia or of undernutrition in geriatric patients: markers of the metabolic syndrome or of undernutrition?

The metabolic syndrome (MS) describes a cluster of metabolic disturbances including type 2 diabetes and/or insulin resistance, hypertension, dyslipidemia and obesity, which predict a high risk of cardiovascular disorders. The associated hyperinsulinemia and hyperleptinemia may contribute to the cardiovascular risk. However, the operational value of the MS in elderly patients is questionable. We therefore investigated the prevalence and significance of the MS in geriatric care. In a survey of 98 consecutive admissions of diabetic patients, <40% had a MS; this is a low value compared to younger diabetic adults, due to a low prevalence of obesity and dyslipidemia. We found a high prevalence of low BMI (<20 kg/m2), hypoalbuminemia and low total cholesterol levels, suggesting that the MS may be modified by undernutrition. The interplay between the MS and undernutrition was further studied in 30 non-diabetic patients. Both leptinemia and insulin resistance indexes (HOMA-IR and QUICKI) were strongly associated with BMI and body fat (measured by Bioelectrical impedance Analysis). BMI, leptinemia and insulin resistance indexes were associated with the Mini Nutritional Assessment (MNA) score. Thus, undernutrition is associated with low leptin and insulin levels and may obscure the association of these parameters with cardiovascular risk. In conclusion, the MS has a low prevalence in our population of elderly diabetic patients, and is of questionable prognostic value. It can be oveshadowed by undernutrition, which is associated with low body weight, leptinemia and insulin resistance indexes. Prevention of undernutrition and/or adjustment to its consequences should receive higher priority in the care of elderly diabetic patients.

Cardiovascular death and the metabolic syndrome: role of adiposity-signaling hormones and inflammatory markers

OBJECTIVE

Levels of adiposity-signaling hormones and inflammatory markers are less favorable in individuals with the metabolic syndrome; their role in the association between the metabolic syndrome and cardiovascular mortality remains unclear.

RESEARCH DESIGN AND METHODS

We conducted a prospective study of 977 men and 1,141 women aged 40-94 years in 1984-1987, followed for mortality for a maximum of 20 years. Adiponectin, leptin, ghrelin, interleukin-6 (IL-6), C-reactive protein (CRP), and Adult Treatment Panel III-defined metabolic syndrome components were measured in fasting blood samples obtained in 1984-1987. Cox-proportional hazards models were used in survival analyses.

RESULTS

The age- and sex-adjusted hazard ratio (HR) (95% CI) for coronary heart disease (CHD) mortality associated with the metabolic syndrome was 1.65 (1.25-2.18) (P < 0.001); this association did not differ significantly by sex, age, or diabetic status (P > 0.2 for each interaction). The association between the metabolic syndrome and CHD mortality was not materially changed after adjustment for adiponectin, leptin, and ghrelin; it was attenuated by 25% after adjustment for IL-6 and 35% after adjustment for CRP. CHD mortality increased linearly with greater levels of IL-6 and CRP (P(trend) < 0.001 for each); the age- and sex-adjusted HRs comparing highest versus lowest quarter were 3.0 (1.87-4.89) for IL-6 and 2.1 (1.41-3.21) for CRP. IL-6, but not CRP, remained a significant predictor of CHD mortality in models including both inflammatory markers and the metabolic syndrome.

CONCLUSIONS

Adiposity-signaling hormones and inflammatory markers explain little to some of the association between the metabolic syndrome and CHD mortality. IL-6 levels predict CHD mortality independently of CRP.

Plasma leptin: associations with metabolic, inflammatory and haemostatic risk factors for cardiovascular disease

BACKGROUND AND AIM

Leptin, an adipocyte-derived protein, regulating food intake and metabolism has been implicated in the development of coronary heart disease. We have examined the relationship between leptin and vascular risk factors including insulin resistance, metabolic, inflammatory and haemostatic risk factors.

METHODS AND RESULTS

The study was carried out in 3640 non-diabetic men aged 60-79 years drawn from general practices in 24 British towns and who were not on warfarin. Leptin was strongly positively correlated with waist circumference (r=0.58; p<0.0001). Leptin concentrations decreased significantly with increasing physical activity and were lowered in cigarette smokers and elevated in men with pre-existing coronary heart disease and stroke; alcohol intake showed no association with leptin concentration. After adjustment for waist circumference and these lifestyle factors, increased leptin was independently associated with significant increases in insulin resistance, triglycerides, inflammatory markers (interleukin-6, C-reactive protein, fibrinogen, plasma viscosity), coagulation factor VIII, endothelial markers von Willebrand factor, tissue plasminogen activator, and fibrin D-dimer levels; and a decrease in HDL-cholesterol. No association was seen between leptin and blood pressure, total cholesterol, glucose or white cell count after adjusting for waist circumference. Further adjustment for insulin resistance abolished the relationships between leptin and triglycerides and HDL-cholesterol, weakened the associations with the haemostatic factors although they remained significant, but made minor differences to the associations with inflammatory markers.

CONCLUSION

Plasma leptin is associated with insulin resistance, inflammation and disturbances in haemostasis independent of waist circumference, suggesting possible pathways by which leptin may influence risk of cardiovascular disease.

Selective imidazoline agonist moxonidine in obese hypertensive patients

Obesity is the major risk factor for the development of hypertension. This association accentuates the risk of cardiovascular disease, as it is frequently accompanied by the components of the metabolic syndrome. This randomised open parallel study evaluated the chronic effects of moxonidine--a selective imidazoline receptor agonist--on blood pressure, plasma catecholamines, leptin, insulin and components of the metabolic syndrome in obese hypertensives. Amlodipine was used as the control drug. Our results showed that moxonidine and amlodipine significantly reduced blood pressure when measured using the oscillometric method and 24-hour blood pressure monitoring. Moxonidine therapy decreased systolic blood pressure from 160.4 +/- 2.4 to 142.1 +/- 3.3 mmHg (p < 0.005) and diastolic blood pressure from 102.4 +/- 1.3 to 89.7 +/- 1.6 mmHg (p < 0.005) after 24 weeks of treatment. Moxonidine administration reduced the supine arterial plasma levels of adrenaline from 63.2 +/- 6.6 to 49.0 +/- 6.7 pg/ml (p < 0.005), the supine arterial plasma levels of noradrenaline from 187.9 +/- 10.7 to 149.7 +/- 13.2 pg/ml (p < 0.01) and the orthostatic venous plasma levels of noradrenaline from 258.6 +/- 25.0 to 190.3 +/- 16.4 pg/ml (p = 0.03). Those variables were not changed by amlodipine. The plasma levels of leptin and insulin 120 min after a glucose load decreased after moxonidine administration from 27.2 +/- 3.5 to 22.6 +/- 2.9 pg/ml (p < 0.05) and from 139.7 +/- 31.2 to 76.0 +/- 15.2 U/ml (p < 0.05), respectively. Amlodipine, however, did not modify those variables. This study showed a comparable reduction in blood pressure with both antihypertensive drugs. Moxonidine decreased sympathetic nervous activity, improved insulin resistance and reduced the plasma levels of leptin.

Early atherosclerosis in childhood: Diagnostic approaches and therapeutic strategies

The long preclinical phase of atherosclerosis involves the interaction of genetic and environmental factors that modulate the progression of disease from early life. Injury to the endothelium is a critical step in atherosclerotic process. Conventional and novel risk factors for coronary artery disease operate from early in life. Noninvasive methods, using mostly ultrasound techniques, have enabled the assessment of early functional and structural arterial disease progression even from the first decade of life. These measures have been shown to be good surrogate markers for atherosclerotic disease progression and future clinical cardiovascular events. Lifestyle and dietary modifications as well as pharmacological interventions have beneficial effects in prevention and restoration of the early arterial changes.

Parathyroid hormone and leptin--new peptides, expanding clinical prospects

There are three injectable and one oral bone-building (i.e., bone anabolic) parathyroid hormone (PTH) peptides. One of the four, Lilly's injectable teriparatide (Forteo), is currently being used, and the other three are in clinical trials. They are being used or assessed only for treating postmenopausal osteoporosis. However, their potential clinical targets now extend far beyond osteoporosis. They can accelerate the mending of even severe non-union fractures; they will probably be used to strengthen the anchorage of pros-theses to bone; they have been shown to treat psoriasis that has resisted other treatments; they can increase the size of haematopoietic stem cell proliferation and accelerate the endogenous repopulation or repopulation by donor transplants of bone marrow depleted by chemotherapeutic drugs; and they may prevent vascular ossification. Leptin, a member of the cytokine superfamily has a PTH-like osteogenic activity and may even partly mediate PTH action. But leptin has two drawbacks that cloud its therapeutic future. First, apart from directly stimulating osteoblastic cells, it targets cells in the hypothalamic ventromedial nuclei and through them it reduces oestrogenic activity by promoting osteoblast-suppressing adrenergic activity. Second, it stimulates vascular and heart valve ossification, which leads to such events as heart failure and diabetic limb amputations.

Leptin is favourably associated with vascular function in obese Caucasians, but not in obese Africans

The comparison of the associations between chronically elevated leptin levels and cardiovascular function in obese Africans and Caucasians has not yet been determined. Therefore, the aim of this study was to compare leptin's associations with cardiovascular function in obese African and obese Caucasian women to determine whether leptin's associations differ between these two groups. This study consisted of two case-case control studies. The first study included a sample of 102 apparently healthy African women and the second, 115 apparently healthy Caucasian women. All lean and obese subjects were selected from each study. The Finometer apparatus was used to obtain a more elaborate cardiovascular profile. Serum leptin levels, insulin levels and the lipid profile were determined. Stroke volume (SV) and cardiac output (CO) were significantly (P< or =0.01) elevated in both obese African and Caucasian groups compared to their lean controls. Total peripheral resistance (TPR) was significantly decreased and arterial compliance (C(W)) significantly increased in both obese African and Caucasian groups. In the obese Caucasian group, diastolic blood pressure (DBP) was significantly (P< or =0.01) lower, SV and C(W) significantly higher (P< or =0.01) and TPR significantly lower compared to the age, body mass index (BMI), and leptin-matched obese African group. After adjusting for age and BMI, leptin correlated negatively with DBP (P< or =0.05; r=-0.33) and TPR (P< or =0.05; r=-0.36) in the obese Caucasian group, but not in the obese African group. Even though leptin levels were similar in obese African and Caucasian women, leptin is favourably associated with vascular function in obese Caucasians, but not in obese Africans.

Leptin and atherosclerosis

Leptin, a 167-amino acid peptide hormone produced by white adipose tissue, is primarily involved in the regulation of food intake and energy expenditure. Leptin receptors are expressed in many tissues including the cardiovascular system. Plasma leptin concentration is proportional to body adiposity and is markedly increased in obese individuals. Recent studies suggest that hyperleptinemia may play an important role in obesity-associated cardiovascular diseases including atherosclerosis. Leptin exerts many potentially atherogenic effects such as induction of endothelial dysfunction, stimulation of inflammatory reaction, oxidative stress, decrease in paraoxonase activity, platelet aggregation, migration, hypertrophy and proliferation of vascular smooth muscle cells. Leptin-deficient and leptin receptor-deficient mice are protected from arterial thrombosis and neointimal hyperplasia in response to arterial wall injury. Several clinical studies have demonstrated that high leptin level predicts acute cardiovascular events, restenosis after coronary angioplasty, and cerebral stroke independently of traditional risk factors. In addition, plasma leptin correlates with markers of subclinical atherosclerosis such as carotid artery intima-media thickness and coronary artery calcifications. Inhibition of leptin signaling may be a promising strategy to slow the progression of atherosclerosis in hyperleptinemic obese subjects.

Arterial distensibility in adolescents: the influence of adiposity, the metabolic syndrome, and classic risk factors

BACKGROUND

Atherosclerosis develops from childhood, but the determinants of this preclinical stage remain uncertain. We examined the relations of classic coronary risk factors, adiposity and its associated metabolic disturbances, to arterial distensibility (a marker of early arterial disease) in 13- to 15-year-olds, some of whom had previously been studied at ages 9 to 11 years.

METHODS AND RESULTS

Brachial artery distensibility was measured by a noninvasive ultrasound technique in 471 British children in whom measures of adiposity, blood pressure, fasting blood lipids, and insulin had been made. All adiposity measures showed strong graded inverse relationships with distensibility. Inverse associations with distensibility were also observed for insulin resistance (homeostasis model assessment), diastolic pressure, C-reactive protein, and the number of metabolic syndrome components present, which had a graded relation to distensibility. Total and LDL cholesterol levels were also inversely related to distensibility, but less strongly than adiposity; homocysteine had no relation to distensibility. Although the relations of total and LDL cholesterol and diastolic pressure to distensibility had been present at 9 to 11 years of age, those of adiposity and insulin resistance were only apparent at 13 to 15 years.

CONCLUSIONS

Adiposity and its metabolic consequences are associated with adverse changes in the arterial wall by the teenage years. The graded relation with increasing adiposity was stronger than that for cholesterol and was seen at body mass index levels well below those considered to represent "obesity." This emphasizes the importance of population-based strategies to control adiposity and its metabolic consequences in the young.

Differential effects of saturated and unsaturated fatty acid diets on cardiomyocyte apoptosis, adipose distribution, and serum leptin

Fatty acids are the primary fuel for the heart and are ligands for peroxisome proliferator-activated receptors (PPARs), which regulate the expression of genes encoding proteins involved in fatty acid metabolism. Saturated fatty acids, particularly palmitate, can be converted to the proapoptotic lipid intermediate ceramide. This study assessed cardiac function, expression of PPAR-regulated genes, and cardiomyocyte apoptosis in rats after 8 wk on either a low-fat diet [normal chow control (NC); 10% fat calories] or high-fat diets composed mainly of either saturated (Sat) or unsaturated fatty acids (Unsat) (60% fat calories) (n = 10/group). The Sat group had lower plasma insulin and leptin concentrations compared with the NC or Unsat groups. Cardiac function and mass and body mass were not different. Cardiac triglyceride content was increased in the Sat and Unsat groups compared with NC (P < 0.05); however, ceramide content was higher in the Sat group compared with the Unsat group (2.9 +/- 0.2 vs. 1.4 +/- 0.2 nmol/g; P < 0.05), whereas the NC group was intermediate (2.3 +/- 0.3 nmol/g). The number of apoptotic myocytes, assessed by terminal deoxynucleotide transferase-mediated dUTP nick-end labeling staining, was higher in the Sat group compared with the Unsat group (0.28 +/- 0.05 vs. 0.17 +/- 0.04 apoptotic cells/1,000 nuclei; P < 0.04) and was positively correlated to ceramide content (P < 0.02). Both high-fat diets increased the myocardial mRNA expression of the PPAR-regulated genes encoding uncoupling protein-3 and pyruvate dehydrogenase kinase-4, but only the Sat diet upregulated medium-chain acyl-CoA dehydrogenase. In conclusion, dietary fatty acid composition affects cardiac ceramide accumulation, cardiomyocyte apoptosis, and expression of PPAR-regulated genes independent of cardiac mass or function.

Differential effect of antioxidant treatment on plasma and tissue paraoxonase activity in hyperleptinemic rats

Recent studies suggest that adipose tissue hormone, leptin, is involved in atherogenesis, especially in obese subjects. Previously, we have demonstrated that experimentally induced hyperleptinemia decreases plasma paraoxonase 1 (PON1) activity. The aim of this study was to investigate whether treatment with synthetic antioxidant, Tempol, modulates the effect of leptin on plasma and tissue PON1 in the rat. Leptin was administered at a dose of 0.25 mgkg-1 s.c. twice daily for 7 days and Tempol was added to the drinking water at a concentration of 2 mM. Leptin reduced plasma PON1 activity toward paraoxon, phenyl acetate and gamma-decanolactone to 71.1, 72.3 and 57.1% of control, respectively. In addition, leptin decreased PON1 activity toward paraoxon in aorta, renal cortex and medulla to 78.6, 49.2 and 48.0% of control, respectively, but had no effect on PON1 in heart, lung and liver. PON1 activity toward phenyl acetate was lower following leptin treatment only in aorta. Leptin increased plasma concentration and urinary excretion of isoprostanes as well as malonyldialdehyde + 4-hydroxyalkenals level in aorta, renal cortex and renal medulla. Coadministration of Tempol prevented leptin-induced oxidative stress and normalized PON1 activity in aorta and kidney. However, Tempol had no effect on plasma PON1 in leptin-treated rats. These data indicate that hyperleptinemia decreases tissue PON1 activity through oxidative stress-dependent mechanism. In contrast, leptin-induced downregulation of plasma PON1 is not mediated by oxidative stress.

Influence of the metabolic syndrome on aortic stiffness in never treated hypertensive patients

BACKGROUND AND AIM

Metabolic syndrome (MS) carries an increased risk for cardiovascular events and there is a growing awareness that large artery stiffening is a powerful predictor of cardiovascular morbidity and mortality. Little is known about the relationship of MS with aortic stiffness. The aim of our study was to analyze, in patients with essential hypertension, the influence of MS, defined according to the criteria proposed by the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (NCEP-ATP III), on carotid-femoral pulse wave velocity (PWV), a measure of aortic stiffness.

METHODS

Ninety-three untreated essential hypertensives, aged between 23 and 61 years, without diabetes mellitus, were studied. All subjects underwent routine blood chemistry, oral glucose tolerance test with glucose and insulin determinations, albumin excretion rate (AER) measurement, 24-h ambulatory blood pressure monitoring, and measurement of carotid-femoral PWV, by means of a computerized method.

RESULTS

Patients with MS (n = 28) showed higher age-adjusted carotid-femoral PWV (10.1 +/- 1.4 vs 9.3 +/- 1.4 m/s; p = 0.01) when compared to subjects without MS. This difference held after controlling for gender and for 24-h mean blood pressure (MBP) (p = 0.02) and lost its statistical significance after further adjustment for AER. In a multiple regression model, excluding the individual components of MS, in which metabolic syndrome was added along with age, gender, smoking habit, LDL cholesterol, HOMA index, 24-h MBP and 24-h heart rate, MS remained independently associated with carotid-femoral PWV (beta = 0.29; p = 0.002). The statistical significance of this association disappeared after the inclusion into this model of AER.

CONCLUSIONS

Metabolic syndrome is associated with an increased aortic stiffness. Main explanatory factors of this association are age, systolic blood pressure and albumin excretion rate.

Obesity is associated with increased arterial stiffness from adolescence until old age

OBJECTIVE

To our knowledge, only two previous studies have investigated the age dependence of the relationship between the characteristics of large arteries and excessive body weight. We therefore investigated whether the relationship between arterial stiffness and body mass index (BMI) was consistent across an age range from 10 to 86 years.

METHODS

Using a cross-sectional population-based design, we randomly recruited 1306 individuals (median age 43.9 years; 50.5% women). Using a wall-tracking ultrasound system, we measured the properties of the carotid, femoral and brachial arteries and carotid-femoral pulse wave velocity. We analysed men and women separately while adjusting for significant covariates, including age, mean arterial pressure, heart rate, current smoking, alcohol intake and use of antihypertensive drugs.

RESULTS

Before and after adjustment, arterial diameter increased with BMI in all territories, with an opposite trend for arterial distensibility. In men and women, the relationships of brachial and femoral properties with BMI were consistent across the whole age range. In men and women, carotid distensibility decreased more with BMI at young than old age. In middle-aged and older women, but not in men of any age, pulse wave velocity increased with higher BMI.

CONCLUSIONS

Across a wide age range, the diameter and stiffness of muscular arteries increased with higher BMI. In elastic arteries, the relationship between arterial stiffness and BMI was more complex and varied with sex and age. The mechanisms underlying the influence of adiposity on the properties of muscular and elastic arteries and the reversibility of these associations by weight reduction at young age need further clarification.

Adipocytokines: leptin--the classical, resistin--the controversical, adiponectin--the promising, and more to come

With the growing prevalence of obesity, scientific interest in the biology of adipose tissue has been extended to the secretory products of adipocytes, since they are increasingly shown to affect several aspects in the pathogenesis of obesity-related diseases. The cloning of the ob gene is consistent with this concept and suggests that body fat content in adult rodents is regulated by a negative feedback loop centred in the hypothalamus. In recent years, a number of additional signalling molecules secreted by adipose tissue have been discovered, commonly referred to as 'adipocytokines'. Among these, adiponectin is perhaps the most interesting and promising compound for the clinician since it has profound protective actions in the pathogenesis of diabetes and cardiovascular disease. Adiponectin is low in obese subjects and, in particular, insulin-resistant patients. In contrast, resistin seems to be of greater relevance in relation to the immune stress response than in the regulation of glucose homeostasis. However, inflammatory processes have recently been connected with the development of atherosclerosis. Finally, little is known regarding the clinical relevance of visfatin. Recent research has revealed many functions of adipocytokines extending far beyond metabolism, such as immunity, cancer and bone formation. This report aims to review some of the recent topics of adipocytokine research that may be of particular importance.

Leptin induces vascular smooth muscle cell hypertrophy through angiotensin II- and endothelin-1-dependent mechanisms and mediates stretch-induced hypertrophy

Various cardiovascular pathologies are associated with vascular smooth muscle cell (VSMC) hypertrophy and elevated plasma leptin levels. We used the rat portal vein (RPV) cultured for three days to investigate the effect of mechanical stretch on autocrine secretion of leptin and the effect of exogenous leptin (3.1 nM) on VSMC. Stretching the RPV significantly up-regulated leptin production by greater than 100-fold and leptin receptor expression by up to 10-fold. In addition, stretch increased tissue weight by 23 +/- 1.3 and 30 +/- 1% (P < 0.05), respectively, in the absence or presence of leptin, although this was significantly attenuated by an antileptin antibody (166 ng/ml). Unstretched RPV weight decreased by 7.5 +/- 1.8% in the absence of leptin, whereas in the presence of leptin, weight increased by 6.5 +/- 1.8% (P < 0.05). VSMC size and [3H]leucine incorporation rates were significantly increased by leptin in stretched and unstretched tissues. Leptin-induced hypertrophy was associated with significant extracellular signal-regulated kinase (ERK1/2) activation as well as increased expression of angiotensinogen, the angiotensin type 1 receptor as well as preproendothelin-1, and the endothelin type A receptor, whereas ERK inhibition or inhibition of either the angiotensin II or endothelin-1 systems at both the synthesis and receptor levels blocked the hypertrophic response. The effects of leptin were also completely blocked by the cholesterol-chelating agent methyl-beta-cyclodextrin. Therefore, our study demonstrates stretch-dependent leptin release and a direct hypertrophic effect of leptin on RPV, the latter likely dependent on intact cholesterol-rich membrane microdomains and locally produced paracrine factors.

Comparison of the effects of valsartan and felodipine on plasma leptin and insulin sensitivity in hypertensive obese patients

Aim of this study was to compare the effect of valsartan and felodipine on blood pressure (BP), plasma leptin (L), insulin sensitivity and plasma norepinephrine (NE) in obese hypertensive patients. Ninty-six obese patients (body mass index [BMI] > or = 30 kg/m2) with mild to moderate essential hypertension (diastolic blood pressure [DBP] > 90 and < 110 mmHg, as evaluated with an appropriately sized cuff) aged 31-60 years, were randomized to a valsartan (80 mg/day for 16 weeks; n = 48) or felodipine (5 mg/day for 16 weeks; n = 48) treatment group after a 2-week wash-out period. After the first 4 weeks of treatment there was a titration with dose-doubling in non responder patients (DBP > 90 mmHg). At the end of the placebo period and of active treatment period, BP and BMI were evaluated and a venous sample was drawn at the same hour in the morning to evaluate plasma L and NE. Insulin resistance index (HOMA-IR) was calculated. No dietary advice was prescribed. Both valsartan and felodipine significantly decreased BP values (-19.3/15 mmHg and -18.9/13.6 mmHg, respectively p < 0.001 vs. placebo), with no difference between treatments. However, felodipine increased plasma NE (+124 pg/ml, +38.2%, p < 0.05 vs. placebo and < 0.01 vs. valsartan) and had no effect on L, body weight and HOMA-IR index, while valsartan did not modify NE and produced a significant reduction in L (-3.7 ng/ml, -10.1%, p < 0.05 vs. placebo), BMI (-1.7 kg/m2, -4.7%, p < 0.01 vs. placebo) and HOMA-IR index (-1.6, -20%, p < 0.05 vs. placebo). These results suggest that in hypertensive obese subjects, treatment with valsartan might offer an advantage over treatment with felodipine, since valsartan may help to improve obesity-related disorders in addition to lowering BP.

Risk factors identified in childhood and decreased carotid artery elasticity in adulthood: the Cardiovascular Risk in Young Finns Study

BACKGROUND

Exposure to risk factors in childhood may have long-term influences on vascular function. We examined the relationship between risk factors identified in childhood and arterial elasticity assessed in adulthood.

METHODS AND RESULTS

Carotid artery compliance (CAC), Young's elastic modulus (YEM), and stiffness index (SI), 3 measures of large-artery elasticity, were assessed with noninvasive ultrasound in 2255 healthy white adults aged 24 to 39 years participating in a population-based cohort study and who had risk factor data available since childhood. In multivariate models, childhood obesity (skinfold thickness) predicted decreased CAC (P<0.001), increased YEM (P<0.01), and increased SI (P<0.01) in adulthood. Childhood blood pressure was inversely associated with CAC (P<0.001) and directly associated with YEM (P<0.001). The number of risk factors identified in childhood, which included high LDL cholesterol (at or above 80th percentile), elevated blood pressure, skinfold thickness, low HDL cholesterol (at or below 20th percentile), and smoking, was related inversely with CAC (P<0.001) and directly with YEM (P<0.001). These associations remained highly significant after adjustment for the number of risk factors identified in adulthood (P=0.005 for CAC and P<0.001 for YEM).

CONCLUSIONS

Cardiovascular risk factors identified in childhood and adolescence predict decreased carotid artery elasticity in adulthood. These data suggest that risk factors operating in early life may have sustained deleterious effects on arterial elasticity.

Endothelial dysfunction: role in obesity-related disorders and the early origins of CVD

Atherosclerotic CVD is the most common cause of death in the West. Yet, its pathogenesis and early development are only partially understood. Central to the early atherosclerotic process is impairment of vascular endothelial function. Endothelial dysfunction can be measured non-invasively and is evident in children before clinical manifestations of atherosclerosis in adulthood. Factors in early life, such as conventional cardiovascular risk factors, or programming by perinatal growth and nutrition strongly affect endothelial function and hence the development of atherosclerosis and CVD. For instance, low birth weight and faster growth early in infancy have a detrimental effect on vascular structure and function. Childhood obesity, a key independent risk factor for CVD, also adversely affects early vascular health. Obesity is associated with endothelial dysfunction and greater arterial stiffness from as early as the first decade of life, while weight loss is beneficial. This effect on vascular function is probably mediated in part by low-grade inflammation and insulin resistance associated with obesity or by the production by adipose tissue of cytokine-like molecules, collectively termed adipokines. A high leptin concentration, in particular, is found in obese individuals and is strongly associated with vascular changes related to early atherosclerosis. The present review focuses on the early origins of endothelial dysfunction, emphasising the role of obesity. It also considers the mechanisms by which obesity impairs endothelial function, understanding of which will be important to further scientific knowledge and to improve public health.

Effects of adipocyte-derived cytokines on endothelial functions: implication of vascular disease

Adipose tissue has recently emerged as an active endocrine organ that secretes a variety of metabolically important substances, collectively called adipocytokines or adipokines. In this review we summarize the effects of the adipokines leptin, adiponectin, and resistin on the vasculature and their potential role for pathogenesis of vascular disease. Leptin is associated with arterial wall thickness, decreased vessel distensibility, and elevated C reactive protein (CRP) levels. Leptin possesses procoagulant and antifibrinolytic properties, and it promotes thrombus and atheroma formation, probably through the leptin receptors by promoting vascular inflammation, proliferation, and calcification, and by increasing oxidative stress. Research for development of pharmacologic antagonism for the leptin receptor is currently under way. Adiponectin inhibits the expression of the adhesion molecules ICAM-1, VCAM-1, and P selectin. Therefore, it interferes with monocyte adherence to endothelial cells and their subsequent migration to the subendothelial space, one of the initial events in the development of atherosclerosis. Adiponectin also inhibits the transformation of macrophages to foam cells in vitro and decreases their phagocytic activity. Resistin, discovered in 2001, represents the newest of the adipokines and was named for its ability to promote insulin resistance. Resistin increases the expression of the adhesion molecules VCAM-1 and ICAM-1, up-regulates the monocyte chemoattractant chemokine-1, and promotes endothelial cell activation via ET-1 release. Although many aspects of its function need further clarification, it appears that resistin will add significantly to our knowledge of the pathophysiology of vascular disease and the metabolic syndrome.

Leptin is independently associated with systolic blood pressure, pulse pressure and arterial compliance in hypertensive African women with increased adiposity: the POWIRS study

High leptin levels are often observed in human obesity and are implicated in obesity-related hypertension. Leptin levels have been found to be higher in hypertensive obese African-American women compared to normotensive African-American women, but a direct association between leptin and blood pressure could not be obtained. Additionally, increased adiposity has been associated with higher aortic stiffness in obese African-American women, but leptin was not included in the study. The effects of leptin on cardiovascular function in African women have not yet been determined. We hypothesised that leptin is directly associated with blood pressure and decreased arterial compliance and that leptin levels are significantly higher in hypertensive overweight/obese African women compared to normotensive overweight/obese African women. A case-case control study was performed which included 98 African women. The subjects were divided into lean normotensive (lean NT), overweight/obese normotensive (OW/OB NT) and overweight/obese hypertensive (OW/OB HT). The Finometer apparatus was used to obtain a more elaborate cardiovascular profile. Serum leptin and insulin levels as well as the HOMA-IR index were determined. Various anthropometric measures were obtained. Leptin levels were elevated (P < or = 0.05) in the OW/OB NT and HT groups compared to the lean NT group, but were similar in the OW/OB NT and HT groups. After adjusting for obesity, insulin resistance, hyperinsulinaemia and age, a direct positive correlation was obtained between leptin and systolic blood pressure (SBP) (P < or = 0.05; r = 0.68) in the OW/OB HT group. Additionally, leptin also correlated negatively with arterial compliance (P< or = 0.05; r = -0.76) and positively with pulse pressure (P < or = 0.05; r = 0.71) in the OW/OB HT group. In conclusion, even though leptin levels were the same in OW/OB HT and NT African women, leptin was directly and positively associated with SBP and pulse pressure and negatively with C(W) only in OW/OB HT African women, independent of obesity, insulin-resistance, hyperinsulinaemia and age.

Cathepsin S, a novel biomarker of adiposity: relevance to atherogenesis

The molecular mechanisms by which obesity increases the risk of cardiovascular diseases are poorly understood. The purpose of this study was to identify candidate biomarkers overexpressed in adipose tissue of obese subjects that could link expanded fat mass to atherosclerosis. We compared gene expression profile in subcutaneous adipose tissue (scWAT) of 28 obese and 11 lean subjects using microarray technology. This analysis identified 240 genes significantly overexpressed in scWAT of obese subjects. The genes were then ranked according to the correlation between gene expression and body mass index (BMI). In this list, the elastolytic cysteine protease cathepsin S was among the highly correlated genes. RT-PCR and Western blotting confirmed the increase in cathepsin S mRNA (P=0.006) and protein (P<0.05) in obese scWAT. The circulating concentrations of cathepsin S were also significantly higher in obese than in nonobese subjects (P<0.0001). Both cathepsin S mRNA in scWAT and circulating levels were positively correlated with BMI, body fat, and plasma triglyceride levels. In addition, we show that the proinflammatory factors, lipopolysaccharide, interleukin-1beta, and tumor necrosis factor-alpha increase cathepsin S secretion in human scWAT explants. This study identifies cathepsin S as a novel marker of adiposity. Since this enzyme has been implicated in the development of atherosclerotic lesions, we propose that cathepsin S represents a molecular link between obesity and atherosclerosis.

Substances produites par le tissu adipeux, obésité et risque vasculaire

Obesity is associated with increased risk of cardiovascular morbidity. Biologically active molecules produced by adipose tissue constitute a critical link between obesity and cardiovascular complications. Adipose tissue has recently been recognized to be an important endocrine organ that controls energy metabolism. It also secretes adipocytokines, which can modify vascular responses, and antifibrinolytics, including plasminogen activator inhibitor 1, which favors fibrin accumulation, and proinflammatory cytokines, which facilitate the inflammatory response. Here we review new advances in our understanding of the mechanisms linking the endocrine activity of adipose tissue to vascular risk.

Body composition and fat repartition in relation to structure and function of large arteries in middle-aged adults (the SU.VI.MAX study)

OBJECTIVE

To investigate associations of body composition assessed by bioimpedance analysis and anthropometric indicators of fat repartition with carotid structure and function.

DESIGN

Cross-sectional epidemiological study.

SUBJECTS

A total of 1014 middle-aged apparently healthy adults participating in the SU.VI.MAX study.

MEASUREMENTS

Body composition (fat mass, fat-free mass) was assessed by bioimpedance analysis and anthropometric indicators of fat repartition (waist circumference (WC); waist-hip-ratio (WHR)) were simultaneously collected. Carotid ultrasound examination included measurements of intima-media thickness (IMT) at the common carotid arteries (CCA) and assessment of atherosclerotic plaques in extracranial carotid arteries. Carotid-femoral pulse-wave velocity (PWV) was used as a marker of aortic stiffness.

RESULTS

In multivariate analyses adjusted for major known cardiovascular risk factors in addition to age, gender and height, fat-free mass, fat mass (FM), and WC were positively associated with CCA-IMT and lumen diameter. No significant association was found with occurrence of carotid plaques. PWV was only associated with WC. Associations of CCA-IMT and PWV with WC were not significant anymore after further adjustment on body mass index (BMI) or FM.

CONCLUSION

WC was the only measurement positively associated with both early atherosclerosis markers such as CCA-IMT and arterial stiffness. Although this association depends on overall adiposity, as assessed by the BMI, it emphasizes the importance of WC in clinical practice and prevention programs as a screening tool for individuals at risk for cardiovascular disease.

Ectopic fat storage in heart, blood vessels and kidneys in the pathogenesis of cardiovascular diseases

In humans and most animal models, the development of obesity leads not only to increased fat depots in classical adipose tissue locations but also to significant lipid deposits within and around other tissues and organs, a phenomenon known as ectopic fat storage. The purpose of this review is to explore the possible locations of ectopic fat in key target-organs of cardiovascular control (heart, blood vessels and kidneys) and to propose how ectopic fat storage can play a role in the pathogenesis of cardiovascular diseases associated with obesity. In animals fed a high-fat diet, cardiac fat depots within and around the heart impair both systolic and diastolic functions, and may in the long-term promote heart failure. Accumulation of fat around blood vessels (perivascular fat) may affect vascular function in a paracrine manner, as perivascular fat cells secrete vascular relaxing factors, proatherogenic cytokines and smooth muscle cell growth factors. Furthermore, high amounts of perivascular fat could mechanically contribute to the increased vascular stiffness seen in obesity. Finally, accumulation of fat in the renal sinus may limit the outflow of blood and lymph from the kidney, which would alter intrarenal physical forces and promote sodium reabsorption and arterial hypertension. Taken together, ectopic fat storage in key target-organs of cardiovascular control may impair their functions, contributing to the increased prevalence of cardiovascular diseases in obese subjects.

Metabolic syndrome is associated with aortic stiffness in untreated essential hypertension

Metabolic syndrome is a powerful predictor of cardiovascular disease in hypertension, and large-artery stiffness is increasingly recognized as a cardiovascular risk factor. We hypothesized that the adverse prognostic significance of the metabolic syndrome in hypertension might be explained in part by its association with aortic stiffness. A total of 169 newly diagnosed, never treated, nondiabetic patients with essential hypertension (men 55%, 48+/-11 years) were classified by the presence (n=45) or absence (n=124) of the metabolic syndrome. All patients underwent aortic and upper limb pulse wave velocity determination by means of an applanation tonometry-based method. Aortic pulse wave velocity had a direct correlation with office and 24-hour systolic pressure (r=0.42 and 0.31, respectively), as well as with waist circumference (r=0.35, all P<0.001), but not with body mass index (r=0.10, P=not significant). Aortic pulse wave velocity was higher in the subgroup with the metabolic syndrome (10.0+/-2.7 versus 8.8+/-2.1 m/s; P=0.003), whereas upper limb velocity did not differ in the 2 groups (8.6+/-1.4 versus 8.7+/-1.5 m/s; P=not significant). In a multiple regression, aortic pulse wave velocity was independently associated with age, systolic blood pressure, and the metabolic syndrome. Only diastolic BP independently predicted upper limb pulse wave velocity. We conclude that in untreated hypertension, the metabolic syndrome is independently associated with a higher aortic, but not upper limb, pulse wave velocity. Central, but not general, adiposity is an important determinant of aortic stiffness in hypertension.

Leptin induces hypertrophy via p38 mitogen-activated protein kinase in rat vascular smooth muscle cells

The hypertrophy of vascular smooth muscle cells (VSMCs) is critical in vascular remodeling associated with hypertension, atherosclerosis, and restenosis. Recently, leptin has appeared to play a pivotal role in vascular remodeling. However, the mechanism by which leptin induces hypertrophy in vascular smooth muscle cells is still unknown. We studied the role of leptin as a potential hypertrophic factor in rat VSMCs. In the present study, leptin significantly increased [(3)H]leucine incorporation and the total protein/DNA ratio in VSMCs. The maximal hypertrophic effect was at 100ng/ml of leptin. Leptin induced phosphorylation and activation of p38 mitogen-activated protein (p38 MAP) kinase and of signal transducers and activators of transcription 3 in a concentration- and time-dependent manner. A p38 MAP kinase inhibitor SB203580 significantly inhibited leptin-induced hypertrophy, AG490 (a JAK2 inhibitor) partially inhibited it, and other MAP kinase inhibitors, PD98059 (an ERK inhibitor) and SP600125 (a JNK inhibitor), had no effect. These results indicate that leptin directly stimulates cellular hypertrophy via p38 MAP kinase in rat VSMCs.

Obesity reveals an association between blood pressure and the G-protein beta3-subunit gene: a study of female dizygotic twins

The 825C>T polymorphism of the G-protein beta3-subunit gene (GNB3) has been associated with hypertension, although results are not entirely consistent. In a sample of 282 female Caucasian dizygotic twins aged 21-80 years, we aimed to investigate the associations between blood pressure and five single nucleotide polymorphisms (SNPs) including the 825C>T and haplotypes of the GNB3 gene. The polymorphisms (-350A>G, 657A>T, 814G>A, 825C>T and 1429C>T) were genotyped by polymerase chain reaction-restriction enzyme assays. Regular association tests did not show a significant effect on blood pressure for any of the five SNPs. However, strongly significant interactions between the -350A>G, 825C>T and 1429C>T loci and adiposity (both body mass index and waist circumference) were observed for systolic blood pressure (Ps < 0.01) as well as diastolic blood pressure (Ps < 0.05), suggesting increases in adiposity amplify the effects of the SNPs on blood pressure. Haplotype analyses confirmed the effects of the GNB3 gene-obesity interaction on hypertension risk. Additionally, sib-transmission disequilibrium tests (sib-TDTs) showed significant associations with blood pressure for the 825C>T and 1429C>T loci. In summary, the presence of obesity reveals an association between blood pressure and the GNB3 gene in White females. Our data suggest that adiposity is a final pathway through which gene-lifestyle interactions may exert their effects on the development of hypertension. Our results from the combined SNP, haplotype and sib-TDT analyses also support the hypothesis that the 825C>T is a susceptibility locus for hypertension, whereas effects of other loci on blood pressure may result from their strong linkage disequilibrium with the 825C>T locus.

Regional body composition as a determinant of arterial stiffness in the elderly: The Hoorn Study

OBJECTIVE

To estimate the relation of precisely measured regional body composition with peripheral and central arterial stiffness in the elderly.

METHODS

We investigated 648 participants (mean age 69.0 +/- 6.0 years) of the Hoorn Study, a population-based cohort study. Trunk fat, leg fat, trunk lean and leg lean mass were distinguished by dual-energy X-ray absorptiometry. We used ultrasound to measure the distensibility and compliance of the carotid, femoral and brachial arteries, and carotid Young's elastic modulus, as estimates of peripheral stiffness. As estimates of central stiffness we measured carotid-femoral transit time, aortic augmentation index and systemic arterial compliance.

RESULTS

After adjustment for sex, age, height, mean arterial pressure, leg lean and leg fat mass, a larger trunk fat mass was consistently associated with higher peripheral arterial stiffness (standardized beta (beta) of mean Z-scores of all three large arteries -0.24, P < 0.001). In contrast, larger leg fat mass (beta = 0.15, P = 0.009) and leg lean mass (beta = 0.09, P = 0.20) were associated with lower peripheral arterial stiffness. Trunk or leg fat mass were not associated with central arterial stiffness. Leg lean mass, however, was consistently associated with lower central arterial stiffness (beta = 0.29, P < 0.001).

CONCLUSIONS

Trunk fat mass may have adverse effects on peripheral, but not on central arterial stiffness, while leg fat was not harmful and may have a slight protective effect. Larger leg lean mass was the most important determinant of lower central arterial stiffness. These results provide a pathophysiological framework to explain not only the higher cardiovascular risk in individuals with larger trunk fat mass, but also the reduced cardiovascular risk in individuals with larger leg lean and fat mass.

Plasma leptin concentration in patients with Type 2 diabetes: relationship to cardiovascular disease risk factors and insulin resistance

AIMS

The aim of this study was to evaluate the relationship of obesity, leptin, insulin resistance and C-reactive protein (CRP) with coronary heart disease (CHD) risk factors in patients with Type 2 diabetes mellitus (DM) with CHD compared with those with Type 2 DM without CHD.

METHODS

Leptin, CRP (high sensitivity assay), fasting plasma insulin, glucose, HbA(1c) and full lipid profile were determined in 58 Type 2 diabetic patients with CHD and 87 Type 2 DM patients without CHD.

RESULTS

were compared between those with and without CHD. Univariate correlation as well as logistic regression analyses were used to relate these markers with traditional CHD risk factors.

RESULTS

Leptin showed significant correlations with BMI (r = 0.59; P < or = 0.0001), waist circumference (r = 0.45; P < 0.0001), CRP (r = 0.36; P < 0.0001), and fasting insulin (r = 0.53; P < 0.0001) as well as with systolic (r = 0.23; P = 0.007) and diastolic (r = 0.23; P = 0.007) blood pressure. However, when those with and without CHD were compared only age (P < 0.0001), duration of diabetes (P < 0.001) and degree of microalbuminuria (P = 0.02) were significantly higher in patients with CHD. Leptin (P = 0.49), CRP (P = 0.19) and lipid parameters were not significantly different between the two groups.

CONCLUSION

Our study confirms a relationship between leptin and CRP with CHD risk factors. The lack of significant difference when patients with and without CHD are compared may be due to the potential confounding effects of treatment with aspirin and statins.

The association between abdominal visceral fat and carotid stiffness is mediated by circulating inflammatory markers in uncomplicated type 2 diabetes

Central obesity, insulin resistance, inflammation, as well as vascular changes are common in patients with type 2 diabetes. In this study we assessed the relationship among stiffness of the carotid artery, visceral fat, and circulating inflammatory markers in type 2 diabetic subjects. Carotid stiffness, quantified as the distensibility coefficient (DC), was measured by ultrasound in asymptomatic, normotensive patients with uncomplicated, well-controlled type 2 diabetes and in controls. Body fat distribution was quantified by magnetic resonance imaging. In patients, the carotid DC was inversely associated with visceral fat area (r = -0.660; P = 0.005) and plasma levels of C-reactive protein (CRP; r = -0.687; P = 0.002), but most strongly with plasma IL-6 (r = -0.766; P < 0.001). In multivariate analysis, the association between DC and visceral fat disappeared after adjustment for CRP and IL-6. Correction for age, body mass index, blood pressure, glycosylated hemoglobin, or fasting plasma glucose did not affect the association between carotid DC and inflammatory markers. Thus, carotid stiffness is associated with visceral obesity in patients with uncomplicated type 2 diabetes, but this association seems to be mediated by circulating IL-6 and CRP, of which IL-6, at least in part, originates from adipose tissue and stimulates hepatic CRP production.

Serum leptin and myocardial infarction in hypertension

The adipose tissue-derived hormone leptin is among the physiologic processes involved in cardiovascular regulation. The aim of the present study was to elucidate if serum leptin may predict cardiovascular risk, particularly myocardial infarction (MI), in hypertensive men and women. In a prospective study cohort of hypertensive men and women, serum leptin was compared in 171 patients with MI and in 342 matched controls. The mean serum concentration of leptin was 25.1 +/- 20.0 ng/ml in the MI patients and 20.0 +/- 16.6 ng/ml in the controls (p = 0.007). The association between serum leptin and MI was independent of traditional risk factors. Leptin concentrations were higher in women than in men. In women, serum leptin was the most important predictor of MI. The present study indicates that serum leptin is associated with MI in a hypertensive population. Leptin concentrations may be of practical importance when estimating the risk of MI, especially in women, where leptin was found to be the most important predictor for MI.

Plasma leptin and prognosis in patients with established coronary atherosclerosis

OBJECTIVES

This study was designed to evaluate the relationship between plasma leptin and prognosis in patients with angiographically confirmed coronary atherosclerosis.

BACKGROUND

Experimental studies suggest that leptin, an adipose tissue-derived hormone, exerts important cardiovascular effects.

METHODS

Study subjects were recruited prospectively from a cohort of patients undergoing clinically indicated coronary angiography (n = 382). The median duration of follow-up was four years. Follow-up information was available for 361 patients.

RESULTS

The combined end point of cardiac death, myocardial infarction (MI), cerebrovascular accident, or re-vascularization occurred in 44 subjects. In the simple Cox model, leptin had a significant (p < 0.001) non-linear/cubic univariate relationship with the combined end point. Other variables associated with prognosis in the univariate analysis were body mass index (BMI), prior MI, insulin resistance, C-reactive protein (CRP), fibrinogen, and number of coronary vessels with >50% stenosis. A positive relationship between leptin and prognosis was also seen when leptin levels were split by quintiles, with a hazard ratio of 6.46 for the highest quintile. The only two variables significantly associated with the combined end point in the multivariate Cox model were leptin (p = 0.004) and number of coronary vessels with >50% stenosis (p < 0.001). A similar relationship between leptin and prognosis was observed when leptin was adjusted for BMI.

CONCLUSIONS

In patients with angiographically confirmed coronary atherosclerosis, leptin is a novel predictor of future cardiovascular events independent of other risk factors, including lipid status and CRP.

Leptin does not induce hypertrophy, cell cycle alterations, or production of MCP-1 in cultured rat and mouse cardiomyocytes

BACKGROUND

Leptin has been proposed as an important mediator in cardiovascular pathophysiology. Patients with congestive heart failure (CHF) present high plasma leptin levels. CHF is generally preceded by myocardial remodeling involving hypertrophy, necrosis, and apoptosis.

AIM

To investigate whether leptin causes hypertrophy or cell cycle alterations, or induces MCP-1 synthesis in cardiomyocytes.

METHODS

Primary cultures of neonatal rat cardiomyocytes (PC) and murine cell line HL-1 were used. RT-PCR was used to identify Ob-Rb gene expression. Metabolic activity and proliferation of cardiomyocytes was studied using MTT and BrdU uptake, while apoptosis was assayed with Hoechst dye vital staining and flow cytometry. Measurement of the cell surface area was used to determine hypertrophy. MCP-1 levels were measured by ELISA.

RESULTS

RT-PCR showed Ob-Rb mRNA expression in HL-1 cells. Exposure to leptin induced no changes in metabolic activity, proliferation, and apoptotic rates, and did not alter cell cycle in cardiomyocytes. Leptin did not increase cell size of cardiomyocytes, and MCP-1 synthesis was not detected in PC and HL-1 cells treated with leptin.

CONCLUSION

This work shows that leptin does not induce changes in viability, proliferation, size or apoptosis of rat neonatal and HL-1 cardiomyocytes, and it does not induce MCP-1 secretion in these cells.

A Case-control Pilot Study on n-3 Polyunsaturated Fatty Acid as a Negative Risk Factor for Myocardial Infarction

The relation between n-3 polyunsaturated fatty acid (PUFA) and nonfatal myocardial infarction is still controversial. A multicenter case-control pilot study on n-3 PUFA as a negative risk factor for myocardial infarction was performed in Niigata prefecture. Seventy-three patients with acute myocardial infarction (AMI) and age and gender matched controls (n = 84) were recruited. Serum leptin levels were significantly higher in patients with AMI than the controls (8.1 +/- 6.7 ng/mL versus 5.8 +/- 3.7 ng/mL, P < 0.01), and serum high-density lipoprotein cholesterol (HDLc) levels were significantly lower in patients with AMI than the controls (46 +/- 10.5 mg/dL versus 60 +/- 15 mg/dL, P < 0.00001). Statistically significant differences were preserved in leptin and HDLc when the data were analyzed separately by gender. Serum levels (%weight) of linolenic acid (C18:3:n3), eicosapentaenoic acid (C20:5:n3), docosapentaenoic acid (C22:5:n3), and total n-3 PUFA were significantly lower in patients with AMI than the control group (P < 0.000001, < 0.05, < 0.05, < 0.05, respectively). The serum n-3 PUFA/saturated fatty acid (SF) ratio and n-3 PUFA/n-9 monounsaturated fatty acid (MUFA) ratio were significantly lower in patients with AMI than the controls (P < 0.05 and < 0.01, respectively). When the subjects were separated into two categories according to an n-3/n-6 PUFA ratio below 0.3 or above 0.3, patients with AMI were more frequently in the former while the controls were more frequently in the latter (P < 0.05). N-3 PUFA may be a negative risk factor for AMI. The results suggest leptin is a risk factor for AMI irrespective of ethnicity and gender.

Endothelial cell function testing: how does the method help us in evaluating vascular status?

Vascular endothelial dysfunction describes a phenotype prone to atherogenesis and clinical complications of this disease process. Endothelium-dependent vasodilator function, reflecting local bioavailability of nitric oxide, can be measured clinically in the peripheral and coronary circulation and corresponds with other measures of endothelial biology including inflammatory status and thrombotic tendency. Although conventional risk factors are key determinants of endothelial dysfunction, many other factors, including the individual's genetic profile, also appear to exert important positive and negative functional influences. Thus, endothelial vasodilator function can be regarded as an integrated index of all atherogenic and atheroprotective factors acting on the vascular wall, reflecting underlying biology and inherent atherosclerotic risk. The potential clinical utility of endothelial vasomotor testing as a prognostic tool in risk assessment and for the monitoring of therapy requires further validation before recommending its wider routine use.

Leptin and asthma in overweight children at 12 years of age

Obesity is suggested as a risk factor for asthma, but the mechanisms are unclear. The relationship between obesity and asthma has not been considered in children born with very low-birth weight (VLBW). We hypothesized that overweight was a contributing factor for asthma in VLBW children, and that leptin and leptin-associated cytokines might play roles in overweight-related asthma. Seventy-four VLBW and 64 normal birth weight (NBW) children participated in a 12-yr follow up study assessing asthma and allergy. Twenty-seven (12 VLBW) of the 138 children were overweight according to the proposed international definition. The diagnosis of current asthma was made by a pediatrician. Serum levels of leptin and interferon (IFN)-gamma were analyzed by enzyme-linked immunosorbent assay (ELISA). Leptin levels were considerably higher in the overweight than in the non-overweight children (median value: 18.1 vs. 2.8 ng/ml, p < 0.001). In the overweight children, current asthmatics had twice as high levels of leptin as children without current asthma (median value: 30.8 vs. 14.3 ng/ml, p = 0.14), but this was not the case in the non-overweight children. IFN-gamma was more often detected in the overweight than in the non-overweight children (61% vs. 12%, p < 0.001), and there was a positive correlation between the levels of leptin and the levels of IFN-gamma (Rho = 0.40, p < 0.001). In the VLBW group, the overweight children had a significantly increased risk for current asthma compared with the non-overweight children after adjustment for the neonatal risk factors [adjusted odds ratio (OR) 5.8, 95% confidence interval (CI): 1.2-27]. Thus, overweight was associated with asthma in the VLBW children. Our hypothesis remained that leptin might be involved in the pathogenesis of asthma in the overweight children, and IFN-gamma might be a pathway in the process of leptin-induced inflammation.

The role of insulin and the adipocytokines in regulation of vascular endothelial function

Vascular integrity in the healthy endothelium is maintained through the release of a variety of paracrine factors such as NO (nitric oxide). Endothelial dysfunction, characterized by reduced NO bioavailability, is associated with obesity, insulin resistance and Type II diabetes. Insulin has been demonstrated to have direct effects on the endothelium to increase NO bioavailability. Therefore altered insulin signalling in the endothelium represents a candidate mechanism underlying the association between insulin resistance and endothelial dysfunction. In recent years, it has become apparent that insulin sensitivity is regulated by the adipocytokines, a group of bioactive proteins secreted by adipose tissue. Secretion of adipocytokines is altered in obese individuals and there is increasing evidence that the adipocytokines have direct effects on the vascular endothelium. A number of current antidiabetic strategies have been demonstrated to have beneficial effects on endothelial function and to alter adipocytokine concentrations in addition to their effects on glucose homoeostasis. In this review we will explore the notion that the association between insulin resistance and endothelial dysfunction is accounted for by adipocytokine action on the endothelium. In addition, we examine the effects of weight loss, exercise and antidiabetic drugs on adipocytokine availability and endothelial function.

Divergent metabolic and vascular phenotypes in pre-eclampsia and intrauterine growth restriction

OBJECTIVE

Pre-eclampsia (PE) and intrauterine growth restriction (IUGR) may both arise secondary to inadequate trophoblast invasion. Maternal vascular disease is evident only in PE. Little mechanistic evidence exists to explain this dichotomy.

METHODS

We employed laser Doppler imaging (LDI) to examine microvascular function in 15 women with PE and 30 healthy pregnant women matched for body mass index (BMI). We also examined 16 women with IUGR. Other factors examined included indices of inflammation, lipoproteins, leptin and insulin concentrations.

RESULTS

Women with PE had double the concentration of leptin and 30% higher triglyceride than controls. Vascular cell adhesion molecule (VCAM)-1 and interleukin (IL)-6 were also higher in women with PE, with both factors correlating with leptin independently of BMI. No difference in microvascular reactivity was observed between controls and women with PE. Women with IUGR had a four-unit smaller BMI than women with PE. When compared with controls, they also had lower low-density lipoprotein cholesterol (LDL-C) concentrations and systemic inflammatory measures were not elevated.

CONCLUSIONS

The technique of LDI is not sensitive to the vascular dysfunction of PE. However, circulating endothelial-derived factors are elevated in association with markedly elevated leptin levels. Therefore, women with IUGR may demonstrate a protective role for their 'leanness' with regard to maternal systemic inflammatory effect.

Overweight in children is associated with arterial endothelial dysfunction and intima-media thickening

OBJECTIVE

We sought to study arterial endothelial function and carotid intima-media thickness (IMT), both early markers of atherosclerosis, in overweight compared to normal children.

DESIGN

Case-control comparison.

SUBJECTS

A total of 36 asymptomatic overweight children (body mass index (BMI)>23; mean 25+/-3) aged 9-12 y and 36 age- and gender-matched nonobese healthy children (BMI<21) from a school community.

MEASUREMENTS

The key parameters were: BMI, arterial endothelial function (ultrasound-derived endothelium-dependent dilation) and carotid artery IMT. The secondary parameters measured included body fat content, waist-hip ratio (WHR), blood pressures, blood lipids, insulin and glucose.

RESULTS

The two groups were well matched for blood pressures, cholesterol and glucose levels, but BMI (P<0.0001), body fat (P=0.001), WHR (P<0.05), fasting blood insulin (P=0.001) and triglyceride levels (P<0.05) were higher in obese children. Overweight was associated with impaired arterial endothelial function (6.6+/-2.3 vs 9.7+/-3.0%, P<0.0001) and increased carotid IMT (0.49+/-0.04 mm vs 0.45+/-0.04 mm, P=0.006). The degree of endothelial dysfunction correlated with BMI (P<0.003) on multivariate analysis.

CONCLUSION

Obesity, even of mild-to-moderate degree, is independently associated with abnormal arterial function and structure in otherwise healthy young children.

Leptin induces hypertrophy via endothelin-1-reactive oxygen species pathway in cultured neonatal rat cardiomyocytes

BACKGROUND

Obesity is a major risk factor for the development of cardiovascular disease. Emerging evidence indicates that leptin, a protein encoded by the obesity gene, is linked with cardiac hypertrophy in obese humans and directly induces cardiomyocyte hypertrophy in vitro. However, the mechanisms by which leptin induces cardiomyocyte hypertrophy are poorly understood.

METHODS AND RESULTS

This study investigated how leptin contributes to cardiomyocyte hypertrophy. Cultured neonatal rat cardiomyocytes were used to evaluate the effects of leptin on hypertrophy. Both endothelin-1 (ET-1) and reactive oxygen species (ROS) levels were elevated in a concentration-dependent manner in cardiomyocytes treated with leptin for 4 hours compared with those cells without leptin treatment. ET-1 stimulated ROS production in a concentration-dependent manner in cardiomyocytes. The augmentation of ROS levels in cardiomyocytes treated with both leptin and ET-1 was reversed by a selective ET(A) receptor antagonist, ABT-627, and catalase, a hydrogen peroxide-decomposing enzyme. After treatment for 72 hours, leptin or ET-1 concentration-dependently increased total RNA levels, cell surface areas, and protein synthesis in cardiomyocytes, all of which were significantly inhibited by ABT-627 or catalase treatment.

CONCLUSIONS

These findings indicate that leptin elevates ET-1 and ROS levels, resulting in hypertrophy of cultured neonatal rat cardiac myocytes. The ET-1-ET(A)-ROS pathway may be involved in cardiomyocyte hypertrophy induced by leptin. ET(A) receptor antagonists and antioxidant therapy may provide an effective means of ameliorating cardiac dysfunction in obese humans.

Leptin, but not adiponectin, predicts stroke in males

OBJECTIVE

To test whether leptin and adiponectin are risk markers for a first-ever stroke. RESEARCH DESIGN, METHODS AND SUBJECTS: A nested case-referent study identified 276 cases with first-ever stroke (234 cases with ischaemic and 42 with haemorrhagic stroke). Prior to the stroke, they had participated in population-based health surveys in northern Sweden (median time between survey and stroke was 4.9 years). Referents were matched for sex, age, date and type of health survey, and geographical region. Putative risk markers for first-ever stroke, including blood pressure (BP), diabetes, smoking, body mass index (BMI), cholesterol, leptin, and adiponectin, were analysed by conditional logistic regression analysis.

RESULTS

Increased BMI, high cholesterol and fasting glucose levels, diabetes mellitus and hypertension were found in future stroke patients. Whereas leptin levels were higher in male subjects (P = 0.004), adiponectin did not differ between groups. A high leptin level independently predicted stroke in men (OR = 2.46; 95% CI 1.08-5.62) but not in women. Adiponectin levels did not predict stroke. Males with high leptin levels developed stroke faster than males with low leptin levels (P = 0.0009), independently of traditional risk factors.

CONCLUSIONS

Leptin may be an important link to the development of cerebrovascular disease in men, whereas adiponectin does not associate with future stroke.

Leptin, obesity and cardiovascular disease

PURPOSE OF REVIEW

Obesity is a risk factor for cardiovascular diseases. Leptin levels are increased in obesity and leptin exhibits cardiovascular actions that may contribute to increased cardiovascular risk. We review the sympathetic, renal and vascular actions of leptin and their relevance to cardiovascular disease.

RECENT FINDINGS

Leptin possesses cardio-renal actions potentially contributing to obesity-related hypertension including generalized sympathoactivation. However, given that leptin resistance occurs in obesity, it has been difficult to link hyperleptinemia with hypertension. One possibility is that leptin resistance is confined to the metabolic effects of leptin, with preservation of its sympathoexcitatory actions. Other mechanisms may contribute to the pressor effects of leptin. For instance, angiotensin II induces leptin generation. Leptin also potentiates the pressor effect of insulin. Therefore, interactions between angiotensin II and insulin with leptin could have deleterious cardiovascular effects in obesity. Additionally, leptin appears to stimulate vascular inflammation, oxidative stress and hypertophy. These actions may contribute to the pathogenesis of hypertension, atherosclerosis, and left ventricular hypertrophy.

SUMMARY

The potential actions of leptin in the pathophysiology of cardiovascular complications of obesity are diverse, despite evidence of leptin resistance to its metabolic actions. However, most information about cardiovascular actions of leptin derives from in-vitro and animal studies. Future research in humans is widely awaited.