Effect of a short-term diet and exercise intervention on oxidative stress, inflammation, MMP-9, and monocyte chemotactic activity in men with metabolic syndrome factors

Cardiovascular manifestations of insulin resistance

Data from the Centers for Disease Control and Prevention indicate that the prevalence of diabetes is increasing steadily and is coupled with a rise in obesity. Studies such as the Nurses' Health Study show that even slight glucose abnormalities, namely insulin resistance, increase the risk of myocardial infarctions, strokes, other cardiovascular disease, and mortality. Insulin resistance was found to accelerate atherosclerosis, inflammation, the onset of diabetes, cardiovascular disease, obesity, hypertension, chronic kidney disease, and dyslipidemia. Adiponectin was found to have potent antiinflammatory and antiatherosclerotic effects. Similarly, studies indicate that peroxisome proliferators-activated receptor agonists have the potential to treat obesity, diabetes, and atherosclerosis. From a preventive standpoint, it was shown that intensive glucose control reduces long-term cardiovascular risk. This intensive control approach included the use of thiazolidinediones (TZDs; troglitazone, pioglitazone, and rosiglitazone), which were demonstrated to have vascular and nonglycemic effects beyond glucose-lowering. A drawback of using TZDs is peripheral fluid retention. The DREAM study showed that participants with impaired fasting glucose or impaired glucose tolerance who are free from cardiovascular disease benefited significantly from taking 8 mg rosiglitazone per day. The ADOPT study provided evidence that rosiglitazone is more efficient at controlling glycemic loss and maintaining low glycosylated hemoglobin levels than metformin and glyburide. Data from the CHICAGO study indicate that the progression of carotid artery intima-media thickness, a marker of atherosclerosis and a surrogate end point for cardiovascular disease, was slowed more with pioglitazone than glimepiride in a racially diverse population of men and women with diabetes mellitus type 2. Overall, investigators have shifted from a focus on hyperglycemia to a multifactorial approach to risk management in diabetes. This multifactorial approach includes intensive glycemic control, lifestyle intervention, and intensive management of comorbid (dyslipidemia, hypertension, early renal disease) conditions. The implementation of a regular, rigorous exercise and diet program greatly decreased insulin resistance and allowed far more patients to reach their glycosylated hemoglobin goals. Studies with atrovastatin show significant improvement in cardiovascular risk factors in patients with diabetes and hypertension. Short-term studies provide support for the administration of a combination of TZD + sulfonylureas in patients with diabetes mellitus type 2. Likewise, studies have shown that a combination of TZDs + metformin reduced the risk of myocardial infarction. Finally, dipeptidyl peptidase-IV inhibitors and glycolipoprotein-1 analogs show potential for helping prevent the deterioration of glucose metabolism in early diabetes mellitus type 2.

Inflammation-induced atherosclerosis as a target for prevention of cardiovascular diseases from early life

Atherogenesis starts from the fetal life, and its natural course consists of interrelations between traditional risk factors and inflammatory, immune, and endothelial biomarkers. Even the early-stages of atherosclerotic lesions, i.e. fatty streaks present the features of chronic inflammation. Markers of inflammation are associated with insulin resistance and major atherosclerosis risk factors. Several studies have confirmed a relationship between surrogate markers of future cardiovascular disease with childhood obesity, notably abdominal obesity, as well as with the degree of obesity. Moreover, functional and structural changes are documented in arteries of children with a familial predisposition to atherosclerotic diseases; these changes are associated with clusters of inflammatory factors and markers of oxidation. In addition to the development of atheromatous plaques, inflammation also plays an essential role in the destabilization of artery plaques, and in turn in the occurrence of acute thrombo-embolic disorders. Markers of inflammation can provide predictive clinical information about outcomes of patients with acute coronary syndromes, independent of the extent of myocardial damage. Moreover, serum levels of the inflammatory markers might add prognostic information provided by traditional risk factors. Platelets have an important role in vascular inflammation and atherosclerosis and in the formation of mural thrombi. As lifestyle modification trials have been successful in decreasing endothelial dysfunction and the level of markers of inflammation among children and adolescents, it is suggested that in addition to expanding pharmacological therapies considered for secondary prevention of atherosclerotic diseases aiming to control the inflammatory process, the importance of primordial/primary prevention of atherosclerosis should be underscored.

Changes in C-reactive protein from low-fat diet and/or physical activity in men and women with and without metabolic syndrome

Change in high-sensitivity C-reactive protein (CRP) from low-fat diet (diet) and physical activity (PA) interventions is relatively unknown for adults with metabolic syndrome. The objective of the study was to assess CRP change (DeltaCRP) with diet and/or PA in men and women with and without metabolic syndrome. Men (n = 149) and postmenopausal women (n = 125) with elevated low-density lipoprotein cholesterol and low high-density lipoprotein cholesterol were recruited into a 1-year randomized controlled trial. Treatment groups were as follows: control, diet (reduced total fat, saturated fat, and cholesterol intake), PA (45-60 minutes at 60%-85% maximum heart rate), or diet + PA. Weight loss was not an intervention focus. Metabolic syndrome was defined using the American Heart Association/National Heart, Lung, and Blood Institute criteria. Stored plasma samples were analyzed for CRP. Change in CRP was compared between treatments, within sex and metabolic syndrome status, using analysis of covariance, including covariates for baseline CRP and body fat change. For women with metabolic syndrome (n = 39), DeltaCRP was greater in diet vs control (-1.2 +/- 0.4, P = .009), diet + PA vs control (-1.3 +/- 0.4, P = .006), and diet + PA vs PA (-1.1 +/- 0.4, P = .02). Women with metabolic syndrome receiving the diet component (diet or diet + PA) had greater DeltaCRP compared with those who did not (control or PA) (P = .001). Change in CRP was not significantly different between intervention groups in men overall, women overall, men with (n = 47) or without metabolic syndrome (n = 102), or women without metabolic syndrome (n = 86). Low-fat diet may be the most effective treatment for reducing CRP in women with metabolic syndrome.

Adipose tissue is not an important source for matrix metalloproteinase-9 in the circulation

OBJECTIVES

Matrix metalloproteinase 9 (MMP-9) is overexpressed in atherosclerotic plaques and in many cancers, and has emerged as a potential circulating biomarker for such diseases. However, adipose tissue (AT) might also produce circulating MMP-9, thereby reducing the value of MMP-9 as a biomarker. The aim of this study was to evaluate the impact of AT on circulating MMP-9, and if the metabolic syndrome might have a modifying effect.

METHODS

Gene expression of MMP-9 was measured in AT, isolated adipocytes, atherosclerotic plaques, macrophages and various other human tissues using real-time PCR. Relationships between plasma MMP-9 (ELISA), adiposity, and metabolic syndrome were analyzed in a population-based cohort of 61-year-old men (n=513). Both AT mRNA levels and circulating levels of MMP-9 were measured in obese subjects (n=40) with and without the metabolic syndrome, treated with a weight-reducing diet.

RESULTS

Bone marrow, atherosclerotic plaques and macrophages had considerably higher MMP-9 mRNA than subcutaneous AT and isolated adipocytes. Among the 61-year-old men, active plasma MMP-9 concentrations were associated with several metabolic syndrome factors, and inflammatory markers, but not body mass index (BMI). In obese patients with, but not without metabolic syndrome AT mRNA levels and circulating MMP-9 declined during weight reduction, but there was no association between changes in plasma MMP-9 and BMI.

CONCLUSION

The results show that adipose tissue per se is not associated with circulating MMP-9. Components of the metabolic syndrome, such as circulating insulin and glucose were related to plasma MMP-9 both in the observation and dietary weight loss studies.

The Influence of Exercise on Metabolic Syndrome in Youth: A Review

The metabolic syndrome (MetS) is a clustering of dyslipidemia, hypertension, glucose intolerance, and central obesity or waist circumference that places individuals at high risk for developing cardiovascular or heart disease. Although first characterized in adults, it has been found in children, but the definition of MetS in children is still controversial. Although MetS is most closely associated with obesity in children, 2 factors believed to affect MetS are physical activity (PA) and aerobic power or fitness. Studies using accelerometry to estimate PA of children have shown that low levels are associated with increased risk of developing MetS. Conversely, high levels of PA at moderate to vigorous intensities reduce the risk. Similarly, low levels of aerobic fitness increase the likelihood of developing MetS. These effects appear to be independent of obesity. Studies have also shown that interventions that increase PA levels and improve aerobic fitness cause a reduction in MetS risk; however, an exact prescription for exercise cannot be presently provided. This review provides an in-depth analysis of what is presently known about the relationship between MetS and PA and aerobic fitness in children. In addition, information is presented regarding potential mechanisms for exercise to affect the major markers of MetS.

Neutrophil activation in morbid obesity, chronic activation of acute inflammation

Recent studies show that morbid obesity is associated with activation of the innate immune response. Neutrophil activation is a fundamental process in the innate immune response. Therefore, the activation state of neutrophils in severely obese subjects and the effect of bariatric surgery on neutrophil activation was evaluated. Neutrophil activation was assessed by measuring circulating concentrations of myeloperoxidase (MPO) and calprotectin in 37 severely obese and 9 control subjects (enzyme-linked immunosorbent assay). Moreover, membrane expression of CD66b on circulating neutrophils was measured using flow cytometry in a group of seven severely obese and six control subjects. Immunohistochemical detection of MPO was performed in adipose and muscle tissue. Plasma MPO and calprotectin levels were significantly increased in severely obese subjects as compared to healthy controls, 27.1 +/- 10.8 vs. 17.3 +/- 5.5 ng/ml (P < 0.001) and 115.5 +/- 43.5 vs. 65.1 +/- 23.1 ng/ml (P < 0.001) for MPO and calprotectin, respectively. In line, CD66b expression was significantly increased in severely obese individuals, 177.3 +/- 43.7 vs. 129.7 +/- 9.2 (mean fluorescence intensity) (P < 0.01). Bariatric surgery resulted in decreased calprotectin, but MPO plasma levels remained elevated. Adipose and muscle tissue did not contain increased numbers of MPO expressing cells in severely obese individuals. These results point out that circulating neutrophils are activated to a greater extent in severely obese subjects. Our data support the finding that the innate immune system is activated in severely obese individuals. Moreover, because neutrophils have a short life span, this indicates that the chronic inflammatory condition associated with morbid obesity is characterized by a continuous activation of the innate immune system.

Metabolic syndrome, endothelial function and lifestyle modification

We evaluated (1) endothelial function (FMD, ICAM-1 and VCAM-1) cross-sectionally in subjects with (MS+) and without (MS-) metabolic syndrome who were at increased risk for cardiovascular disease due to either HNBP and/or IGR, and (2) examined in a subgroup of subjects the effects of 24-week lifestyle modification on endothelial function. MS components, FMD by Doppler ultrasound, ICAM-1 and VCAM-1 by fasting blood samples were assessed. All of the endothelial functions were similar between MS- and MS+. Although waist circumference, blood pressure, and fasting glucose showed improvements, endothelial function remained unchanged following the intervention. The results showed that in our subject population, MS does not reduce endothelial function, and our 24-week lifestyle modification programme did not result in an improvement in endothelial function in MS+ despite the improvements in some MS components.

A randomized controlled trial of the effects of flaxseed lignan complex on metabolic syndrome composite score and bone mineral in older adults

A randomized double-blind placebo controlled study design was used to assess the effects of flaxseed lignan complex supplementation during exercise training on a metabolic syndrome composite score and osteoporosis risk in older adults. A total of 100 subjects (>or=50 years) were randomized to receive flaxseed lignan (543 mg.day-1 in a 4050 mg complex) or placebo while completing a 6 month walking program (30-60 min.day-1, 5-6 days.week-1). Fasting serum glucose, triacylglycerol (TAG), high-density lipoprotein (HDL) cholesterol, low-density lipoprotein cholesterol, total cholesterol, interleukin-6, and tumor necrosis factor-alpha were measured every 2 months, while body composition, bone mineral density, and resting blood pressure were assessed at baseline and at 6 months. A composite Z score of 6 risk factors for metabolic syndrome (fasting glucose, HDL cholesterol, TAG, abdominal adiposity, blood pressure, and inflammatory cytokines) was calculated at baseline and at 6 months. Men taking placebo increased metabolic syndrome composite Z score (p < 0.05), but there were no changes in the other groups. A significant group x sex x time interaction was noted for TAG (p = 0.017) and diastolic blood pressure (p = 0.046), with men taking flaxseed lignan decreasing diastolic blood pressure relative to men taking placebo, and men taking placebo increasing TAG relative to men taking flax lignan. There were no differences between groups for change in bone measures, body composition, lipoproteins, or cytokines. Males taking the flaxseed lignan complex reduced metabolic syndrome score relative to men taking placebo, but a similar trend was not seen in females. Flaxseed lignan had no effect on bone mineral density or content, body composition, lipoproteins, glucose, or inflammation.

Effects of hypocaloric very-low-carbohydrate diet vs. Mediterranean diet on endothelial function in obese women*

Obesity is a cardiovascular risk factor associated with endothelial dysfunction, but the effect of different weight loss strategies on endothelial function is not known. The effect of diet on endothelial function in two hypocaloric diets, a very-low-carbohydrate diet (A) and a Mediterranean diet (M), was measured by brachial artery flow-mediated dilation (FMD). Design Using a longitudinal, randomized, open study design, subjects were engaged in a 2-month weight loss diet. FMD, inflammatory cytokines [interleukin-6 (IL-6) and tumour necrosis factor-alpha] and a marker of oxidative stress [8-iso-prostaglandin F2alpha (8-iso-PGF2alpha)] were measured in subjects on three occasions: before initiating the diet (T0), after 5-7 days of dieting (T5) and after 2 months of dieting (T60). The very short- and medium-term time points were established to discriminate respectively the effect of the diet itself (T5) from that of weight loss (T60). Twenty overweight/obese but otherwise healthy women (BMI: 27-34.9 kg m(-2); age 30-50 years) completed the study. Results Group A lost more weight (mean +/- SEM; -7.6 +/- 0.8 kg) than group M (-4.9 +/- 0.6 kg, P = 0.014) at T60. The FMD was not significantly different between the two groups at T0 (group A: 12.2 +/- 2.9% vs. group B: 10.3 +/- 2.3%, P = ns). In group A, FMD was significantly reduced at T5 and returned to baseline at T60; in group M, FMD increased at T5 and returned to baseline at T60 (P = 0.007 for diet x time interaction). Serum concentrations of IL-6 and 8-iso-PGF2alpha were not significantly different between the two groups at T0 and increased significantly at T5 only in group A (P < 0.001 and P < 0.005 respectively). Conclusion As endothelial dysfunction is known to be associated with acute cardiovascular events, this study suggests that the cardiovascular risk might be increased in the first days of a very-low-carbohydrate diet.

The effect of a 12 week walking intervention on markers of insulin resistance and systemic inflammation

OBJECTIVES

The purpose of the present study was to determine whether a community-based walking intervention, using pedometers, is effective in reducing systemic inflammatory markers.

METHODS

Participants (age=49(8.9)) were recruited in Glasgow, United Kingdom, from August to December 2006 and were randomly assigned to a control (n=24; 6 males, no change in walking) and intervention group (n=24; 5 males gradually increasing walking by 3000 steps/day on 5 days of the week). Blood samples were collected at baseline, and after 12 weeks, and analysed for glucose, insulin, high sensitivity C-reactive protein (hsCRP), interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6R), tumour necrosis factor-alpha (TNF-alpha) and soluble TNF receptors I and II (sTNFR1 and sTNFRII).

RESULTS

In the control group baseline step counts were 6356 (2953) steps/day and did not change (P>0.05) after 12 weeks, 6709 (2918) steps/day. The intervention group increased (P<0.001) step count from 6682 (3761) steps/day at baseline to 10182 (4081) steps/day at 12 weeks. Over the 12 week period there was no change in any other variables measured, in either control or intervention group.

CONCLUSION

We conclude that the current community-based intervention did not affect systemic markers of inflammation or insulin sensitivity.

Matrix metalloproteinase-2 and -9 levels in obese patients

The data reported in literature revealed a novel function for matrix metalloproteinases (MMPs) as modulators of adipogenesis. However, their expression profile and role in the cellular microenvironment during obesity-mediated adipose tissue development remain poorly defined. The authors hypothesized that MMP-2 and MMP-9 levels might be abnormal in obesity, reflecting alterations in extracellular matrix (ECM) turnover. One hundred and sixty three obese patients and 165 controls were enrolled. The following were measured: body mass index (BMI), waist circumference (WC), fasting plasma glucose (FPG), fasting plasma insulin (FPI), homeostasis model assessment (HOMA) index, systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides (Tg), lipoprotein(a) (Lp(a)), and plasma levels of MMP-2 and MMP-9. A significant increase of BMI and WC (p< .0001) was observed in obese patients. No FPG change was present in obese group, whereas FPI and HOMA index increases (p< .0001) were obtained in obese patients compared to control subjects. No SBP and DBP variations were observed in obese group. Significant TC and LDL-C increases (p< .0001) were present in obese patients, whereas no HDL-C, Tg, and Lp(a) changes were obtained in both groups. MMP-2 and MMP-9 levels were significantly higher in obese group (p< .0001). Plasma levels of MMP-2 and MMP-9 are increased in obese patients which may reflect abnormal ECM metabolism.

Effect of exercise on cardiac tissue oxidative and inflammatory mediators in chronic kidney disease

BACKGROUND

Chronic renal failure (CRF) results in diminished physical activity and increased risk of cardiovascular disease (CVD). CVD risk factors are raised by sedentary life style and ameliorated by physical fitness in the general population. Accordingly, exercise improves hypertension, endothelial dysfunction, insulin resistance, dyslipidemia, inflammation and oxidative stress in high-risk populations. This study was designed to explore the effect of exercise on oxidative and inflammatory mediators in the left ventricle (LV) of CRF rats.

METHODS AND RESULTS

One week after 5/6 nephrectomy female rats were housed in either regular cages or cages equipped with running wheels for 4 weeks. Sham-operated rats housed in regular cages served as controls. Sedentary CRF rats exhibited azotemia, hypertension, anemia, oxidative stress, activation of NF-kappaB and upregulations of reactive oxygen species-generating enzyme, NAD(P)H oxidase, MCP-1, cyclooxygenase-2 (COX-2), and PAI-1 in LV. The CRF rats assigned to the exercise group ran 6.8 +/- 0.7 km/day and 72 +/- 8 min/day. Voluntary exercise reversed NF-kappaB activation and lowered NAD(P)H oxidase, PAI-1, MCP-1 and COX-2 abundance, increased LV mass by raising myofibrillar proteins and ameliorated anemia without affecting renal function or arterial pressure.

CONCLUSIONS

CRF resulted in upregulation of prooxidant/proinflammatory pathways in LV. These changes were ameliorated by exercise, which indicates the potential cardiovascular benefit of exercise in renal insufficiency.

Insulin resistance: a proinflammatory state mediated by lipid-induced signaling dysfunction and involved in atherosclerotic plaque instability

The dysregulation of the insulin-glucose axis represents the crucial event in insulin resistance syndrome. Insulin resistance increases atherogenesis and atherosclerotic plaque instability by inducing proinflammatory activities on vascular and immune cells. This condition characterizes several diseases, such as type 2 diabetes, impaired glucose tolerance (IGT), impaired fasting glucose (IFG), obesity, hypertension, dyslipidemia, and other endocrinopathies, but also cancer. Recent studies suggest that the pathophysiology of insulin resistance is closely related to interferences with insulin-mediated intracellular signaling on skeletal muscle cells, hepatocytes, and adipocytes. Strong evidence supports the role of free fatty acids (FFAs) in promoting insulin resistance. The FFA-induced activation of protein kinase C (PKC) delta, inhibitor kappaB kinase (IKK), or c-Jun N-terminal kinase (JNK) modulates insulin-triggered intracellular pathway (classically known as PI3-K-dependent). Therefore, reduction of FFA levels represents a selective target for modulating insulin resistance.

Impact of the L-arginine-Nitric Oxide Pathway and Oxidative Stress on the Pathogenesis of the Metabolic Syndrome

The discovery of the physiological roles of nitric oxide has revolutionized the understanding of regulation of vascular tone, platelet adhesion and aggregation, and immune activation. Perhaps the most intriguing aspect of nitric oxide (NO) is that it is a gas that, in the absence of receptors, can regulate both normal physiological events and mediate cytotoxicity under pathological conditions. NO is produced from L-arginine by NO synthases (NOS), yielding L-citrulline and NO. The regulation of L-arginine pathway activity occurs at the level of NO production. The metabolic syndrome is a cluster of insulin resistance, elevated blood pressure, and atherogenic dyslipidemia, a common basis of cardiovascular disease. It occurs in genetically susceptible individuals with environmental influences and has serious economic and social consequences. Pharmacological and non-pharmacological therapies should be individualized and targeted to normalize its alterations of blood pressure, HDL cholesterol, triglycerides and glucose values. Despite the increasing prevalence of the metabolic syndrome in the last decades, there has been little progress in the understanding of the precise mechanisms involved in the pathogenesis of this syndrome and its complications. Emerging evidence is available that NO, inflammation and oxidative stress play important roles in the physiopathology of this syndrome. This review summarizes and evaluates the participation of the L-arginine-NO pathway and oxidative stress in the physiopathology of the metabolic syndrome and cardiovascular events at the systemic level, as well as the effects of exercise on this syndrome.

Vascular stiffness is related to superoxide generation in the vessel wall

OBJECTIVES

Oxidative stress causes endothelial dysfunction and plays a major role in the pathogenesis of cardiovascular disease. Increased vascular stiffness is an intermediate phenotype in the development of cardiovascular disease. We hypothesized that vascular stiffness is partially determined by oxidative stress.

METHODS

We examined 163 participants out of whom 80 had coronary artery disease. Vascular stiffness was assessed by pulse wave analysis, pulse wave velocity and measurement of aortic compliance by cardiac MRI. Circulating markers of oxidative stress and vascular superoxide generation in saphenous vein were measured.

RESULTS

After adjustment for age, sex, BMI, heart rate, blood pressure and lipids only carotid-femoral pulse wave velocity and aortic compliance were different between patients and control group. Aortic compliance was reduced (11.4 +/- 6.3 vs. 13.9 +/- 7.3 ml x 10(-3) per mmHg; P = 0.035) and vascular superoxide generation increased (1.01 +/- 0.45 vs. 0.76 +/- 0.44 nmol/mg per min; P = 0.035) in patients with coronary artery disease compared with those without. In a multiple stepwise regression analysis, aortic compliance was determined by age (P < 0.001) and vascular superoxide production (P = 0.033). CYBA C242T and NOS3 G894T polymorphisms had additive effects on vascular superoxide generation (P = 0.026) and xanthine oxidase activity was increased in patients with CAD (P = 0.043). Genetic factors (P = 0.033) and xanthine oxidase activity (P < 0.001) were also related to aortic compliance.

CONCLUSION

By measuring vascular superoxide generation and aortic compliance using cardiac MRI, we demonstrated a functional relationship between oxidative stress and vascular stiffness. Patients identified with high levels of vascular stiffness are most likely to benefit from strategies to reduce vascular oxidative stress.

The metabolic syndrome is associated with circulating adipokines in older adults across a wide range of adiposity

BACKGROUND

Circulating levels of adipokines are elevated with adiposity and are closely linked with the clustering of traditional metabolic risk factors for cardiovascular disease. The purpose of this study was to examine the relationship of metabolic syndrome to several adipokines and the role of total and visceral adiposity in influencing this relationship in older adults.

METHODS

A cross-sectional analysis was conducted including 1914 individuals aged 70-79 years without cardiovascular disease or type 2 diabetes. The metabolic syndrome was defined by the updated Adult Treatment Panel III criteria. Circulating levels of leptin, adiponectin, plasminogen activator inhibitor type 1 (PAI-1), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and C-reactive protein (CRP) were measured. Body composition and abdominal visceral fat area were determined.

RESULTS

Both the presence of metabolic syndrome and the number of metabolic syndrome components were associated with higher levels of leptin, PAI-1, IL-6, TNF-alpha, and CRP and with lower levels of adiponectin (all p <.0001). The odds ratios for the prevalence of metabolic syndrome associated with adipokines were attenuated after adjustment for total fat mass and/or visceral fat area, but remained significant. Levels of leptin, PAI-1, IL-6, and TNF-alpha were higher (all p <.05 to p <.0001), and adiponectin was lower (all p <.0001), in persons with, compared to those without, metabolic syndrome within each tertile of percent body fat.

CONCLUSION

The metabolic syndrome is associated with adipokines in older adults across a wide range of adiposity, including in those with low or normal overall fatness.

Effect of exercise training on aortic tone in chronic renal insufficiency

BACKGROUND

Chronic renal insufficiency (CRI) is associated with a high incidence of hypertension (HTN), endothelial dysfunction, atherosclerosis and cardiovascular disease. Sedentary life style increases, whereas regular exercise reduces the risk of cardiovascular disease. This study was designed to test the effect of regular exercise on vasodilatory and vasoconstrictive responses of the thoracic aorta in rats with renal mass reduction.

METHODS

One week after 5/6 nephrectomy (CRI) or sham operation (control), rats were housed in either regular cages or cages equipped with running wheels for 4 weeks. Thereafter, thoracic aorta was harvested and contractile response to potassium and phenylephrine (PhE), and relaxation response to acetylcholine (ACh) and sodium nitroprusside (SNP) were determined.

RESULTS

Compared with the control animals, sedentary CRI animals exhibited significant azotemia, proteinuria, HTN, oxidative stress, and increased sensitivity to potassium and PhE, and reduced sensitivity to ACh and SNP. Exercise training for 4 weeks reduced oxidative stress, reversed CRI-induced heightened sensitivity of the aorta to PhE and potassium, and restored its sensitivity to ACh (but not SNP) without affecting arterial pressure or renal function.

CONCLUSIONS

CRI results in heightened sensitivity to potassium- and alpha-1 adrenergic-mediated contractility and depressed sensitivity to endothelium-dependent relaxation in the aorta. Regular exercise improves these abnormalities without affecting arterial pressure or renal function. These observations suggest that exercise training can improve vascular function in animals, and perhaps humans, with chronic kidney disease.

The effect of serum withdrawal on the protein profile of quiescent human dermal fibroblasts in primary cell culture

The effect of serum deprivation on proliferating cells is well known, in contrast its role on primary cell cultures, at confluence, has not been deeply investigated. Therefore, in order to explore the response of quiescent cells to serum deprivation, ubiquitous mesenchymal cells, as normal human dermal fibroblasts, were grown, for 48 h after confluence, in the presence or absence of 10% FBS. Fibroblast behaviour (i.e. cell morphology, cell viability, ROS production and elastin synthesis) was evaluated morphologically and biochemically. Moreover, the protein profile was investigated by 2-DE and differentially expressed proteins were identified by MS. Serum withdrawal caused cell shrinkage but did not significantly modify the total cell number. ROS production, as evaluated by the dihydroethidium (DH2) probe, was increased after serum deprivation, whereas elastin synthesis, measured by a colorimetric method, was markedly reduced in the absence of serum. By proteome analysis, 41 proteins appeared to significantly change their expression, the great majority of protein changes were related to the cytoskeleton, the stress response and the glycolytic pathway. Data indicate that human dermal fibroblasts in primary cell culture can adapt themselves to environmental changes, without significantly altering cell viability, at least after a few days of treatment, even though serum withdrawal represents a stress condition capable to increase ROS production, to influence cell metabolism and to interfere with cell behaviour, favouring the expression of several age-related features.

Matrix metalloproteinases 2 and 9 and their tissue inhibitors 1 and 2 in premenopausal obese women: relationship to cardiac function

BACKGROUND

Myocardial fibrosis is one of the mechanisms underlying left ventricular (LV) dysfunction in obese patients and may result from dysregulation of extracellular matrix (ECM) turnover. Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) represent a regulatory system playing a crucial role in ECM metabolism.

OBJECTIVES

We sought to assess plasma levels of MMP-2, MMP-9, TIMP-1 and TIMP-2 in obese young women and to evaluate the association between MMP/TIMP system components and LV function in this population.

DESIGN

Prospective, cross-sectional study.

SETTING

University hospital.

PATIENTS

Seventy-one women aged < 35 years with body mass index > 30 kg m(-2) and 30 healthy slim female controls.

MAIN OUTCOME MEASURES

Plasma MMP-2, MMP-9, TIMP-1 and TIMP-2 measurements and echocardiographic studies, including LV strain/strain rate evaluation.

RESULTS

We demonstrated increased levels of MMP-9 and TIMP-1 and decreased MMP-2 in the obese population. LV dysfunction shown in patients with obesity was characterized by significantly lower values of strain/strain rate parameters. Plasma MMP-2 correlated positively and TIMP-1 negatively with systolic strain (r = 0.39, P < 0.001 and r = -0.40, P < 0.001, respectively), peak systolic strain rate (r = 0.38, P < 0.001 and r = -0.27, P < 0.03, respectively) and peak early diastolic strain rate (r = 0.40, P < 0.001 and r = -0.24, P < 0.05, respectively). Plasma MMP-2, fasting insulin and body mass index proved the only independent determinants of strain/strain rate parameters of LV systolic and diastolic performance in obese subjects.

CONCLUSIONS

In premenopausal obese women (1) plasma MMP/TIMP profile is altered, (2) abnormalities of LV function are related to the changes in the MMP/TIMP system that might promote attenuated ECM degradation, mainly to the downregulation of MMP-2.

Challenges for modeling and interpreting the complex biology of severe injury and inflammation

Human injury is associated with inflammatory responses that are modulated by the acute and chronic activity of endogenous factors and exogenous interventions. A characteristic feature of chronic, severe inflammatory states is the diminished signal output variability of many organ systems, including innate immune responsiveness and endogenous neural and endocrine-mediated functions. The attenuation of signal/response variability and integration of feedback capacity may contribute to systemic and tissue-specific deterioration of function. Some well-intentioned therapies directed toward support of systemic and tissue functions may actually promote the loss of system(s) adaptability and contribute to adverse outcomes in severely stressed patients. In vivo and in silico models of stress, injury, and infection have yet to fully define the influences of ongoing stressful stimulae as well as genetic variation and epigenetic factors in the context of an evolving inflammatory state. Experimental and human models incorporating variable, antecedent stress(es) and altered neuroendocrine rhythms might approximate the altered adaptability in immune and organ function responses. Such models may also provide insights into the salient mechanisms of risk and outcome more precisely than do the constrained study conditions of current animal or human models of systemic inflammation.

Oxidative stress and potential interventions to reduce oxidative stress in overweight and obesity

PURPOSE

Obesity may be a state of chronic oxidative stress. Oxidative stress may be the mechanism underlying the development of co-morbidities in obesity. This review provides a summary of the available evidence regarding systemic oxidative stress in young, older and clinical obese populations.

METHODS

Medline was searched for all available articles published between 1975 and 2006 that evaluated oxidative stress biomarkers in resting conditions or following various interventions in overweight and obese humans.

RESULTS

Obesity elevates oxidative stress in young, old and clinical populations as shown by elevations in lipid peroxidation (malondialdehyde, hydroperoxides, 4-hydroxynonenal, isoprostanes, conjugated dienes) or protein oxidation (8-hydroxy-deoxyguanosine). Lipid peroxidation is associated with several indices of adiposity and a low systemic antioxidant defence (i.e. antioxidant enzymes, tissue dietary antioxidants, glutathione). Oxidative stress may be exacerbated with acute exercise, advancing age or co-existing clinical conditions and may be corrected by improving antioxidant defences through fat volume reduction via surgery, pharmacological agents, exercise and/or dietary modification.

CONCLUSION

Oxidative stress is related to chronic disease in obesity, but is reversible with one or more interventions described above.

The potential anti-inflammatory benefits of improving physical fitness in hypertension

Hypertension is associated with an increased risk of stroke and atherosclerosis. In addition to elevated blood pressure, hypertension is characterized by neuroendocrine and immune activation, including elevated levels of C-reactive protein, inflammatory cytokines, and soluble adhesion molecules, which are predictive of morbidity and mortality outcomes. Pharmacological treatment for hypertension reduces blood pressure, but has limited effectiveness in reducing the accompanying inflammation and its associated morbidity and mortality. Exercise and diet interventions regularly show reductions in blood pressure in hypertensive individuals. Similar interventions in other populations show reductions in many inflammatory markers, but these effects have not been routinely examined in hypertensive individuals. The mechanisms through which exercise might exert an anti-inflammatory action include the sympathetic nervous system, the hypothalamic-pituitary-adrenal axis, as well as direct effects of blood pressure. Here, exercise is promoted as a potentially effective treatment for both the elevated blood pressure and chronic inflammation found in hypertension.

Visceral and Subcutaneous Adipose Tissue Volumes Are Cross-Sectionally Related to Markers of Inflammation and Oxidative Stress

BACKGROUND

Excess adiposity is associated with greater systemic inflammation. Whether visceral adiposity is more proinflammatory than subcutaneous abdominal adiposity is unclear.

METHODS AND RESULTS

We examined the relations of abdominal subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT), assessed by multidetector computerized tomography, to circulating inflammatory and oxidative stress biomarkers in 1250 Framingham Heart Study participants (52% women; age 60+/-9 years). Biomarkers were examined in relation to increments of SAT and VAT after adjustment for age, sex, smoking, physical activity, menopause, hormone replacement therapy, alcohol, and aspirin use; additional models included body mass index and waist circumference. SAT and VAT were positively and similarly (with respect to strength of association) related to C-reactive protein, fibrinogen, intercellular adhesion molecule-1, interleukin-6, P-selectin, and tumor necrosis factor receptor-2 (multivariable model R2 0.06 to 0.28 [SAT] and 0.07 to 0.29 [VAT]). However, compared with SAT, VAT was more highly associated with urinary isoprostanes and monocyte chemoattractant protein-1 (SAT versus VAT comparison: isoprostanes, R2 0.07 versus 0.10, P=0.002; monocyte chemoattractant protein-1, R2 0.07 versus 0.08, P=0.04). When body mass index and waist circumference were added to the models, VAT remained significantly associated with only C-reactive protein (P=0.0003 for women; P=0.006 for men), interleukin-6 (P=0.01), isoprostanes (P=0.0002), and monocyte chemoattractant protein-1 (P=0.008); SAT only remained associated with fibrinogen (P=0.01).

CONCLUSIONS

The present cross-sectional data support an association between both SAT and VAT with inflammation and oxidative stress. The data suggest that the contribution of visceral fat to inflammation may not be completely accounted for by clinical measures of obesity (body mass index and waist circumference).

Postprandial hyperglycemia/hyperlipidemia (postprandial dysmetabolism) is a cardiovascular risk factor

Epidemiologic data indicate that a postprandial state characterized by abnormally increased levels of glucose and lipids (also referred to as postprandial dysmetabolism) is an independent predictor of future cardiovascular events, even in nondiabetic subjects. The cardiovascular toxicity of postprandial dysmetabolism is mediated by oxidant stress, which is directly proportional to the increase in glucose after a meal. This transient increase in free radicals acutely triggers inflammation, endothelial dysfunction, hypercoagulability, sympathetic hyperactivity, and a cascade of other atherogenic changes. The postprandial dysmetabolism hypothesis has been bolstered by interventional studies that have demonstrated that blunting the postprandial spikes in glucose and lipids improves inflammation and endothelial function immediately. Early randomized controlled trials indicate that reducing postprandial dysmetabolism appears to significantly slow atherosclerotic progression and may improve cardiovascular prognosis. In conclusion, postprandial dysmetabolism appears to be an important proximate cause of adverse cardiovascular events. Addressing this fundamental and largely unrecognized condition will require specific screening and treatment strategies. Diet, exercise, and various pharmacologic agents can improve postprandial dysmetabolism. Using these strategies may help improve the prognosis for patients with diabetes mellitus and/or coronary heart disease.

Metaloproteasas, remodelado vascular y syndromes aterotrombóticos

Defects in the synthesis and breakdown of the extracellular matrix (ECM) are now seen as key processes in the development of atherosclerosis and its thrombotic complications. Correlations have been observed between circulating levels of ECM biomarkers and the clinical manifestations of and risk factors for atherosclerosis. Several matrix metalloproteinases (MMPs), endopeptidases that can degrade the ECM, such as MMP-9 and MMP-10, play important roles in the pathophysiology of atherothrombosis and contribute to the expansion of abdominal aortic aneurysms. Moreover, they may also be useful biomarkers of atherosclerotic risk and serve as predictors of coronary and cerebrovascular disease recurrence. Although at present the effect of tissue inhibitors of MMPs (TIMPs) on cardiovascular disease prognosis is still uncertain, the ECM could be a promising therapeutic target in atherothrombotic disease, and several MMP inhibitors are currently undergoing clinical trials.

Effect of short-term Pritikin diet therapy on the metabolic syndrome

The Pritikin Program (Aventura, FL) involves the use of a very-low-fat, low-sodium, high-fiber diet and exercise to decrease the risk of coronary heart disease (CHD). This study evaluated the effect of short-term Pritikin therapy on the metabolic risk factors for CHD in patients with the metabolic syndrome. Sixty-seven subjects who had the metabolic syndrome and attended the Pritikin Longevity Center & Spa for 12-15 days were studied. Short-term Pritikin therapy improved most CHD risk factors: body mass index decreased by 3% (P<.001); systolic and diastolic blood pressure, and serum glucose and low-density lipoprotein cholesterol concentrations decreased by 10%-15% (P<.001); serum triglyceride concentration decreased by 36% (P<.001); and 37% of subjects no longer met National Cholesterol Education Program criteria for the metabolic syndrome. Serum high-density lipoprotein cholesterol, however, decreased by 3% (P<.05). These data demonstrate that brief treatment with a very-low-fat, low-sodium, high-fiber diet and regular exercise simultaneously improves multiple CHD risk factors in patients with the metabolic syndrome.

High, but not moderate frequency and duration of exercise training induces downregulation of the expression of inflammatory and atherogenic adhesion molecules

BACKGROUND

Lifestyle changes which include daily exercise training have been shown to slow the progression of coronary artery disease. We designed a study to examine the effects of a multifactorial intervention on atherogenic adhesion molecules on the surface of monocytes in patients with coronary artery disease.

METHODS

We randomized 39 patients with coronary artery disease to (i) an intervention program which consisted of 4 weeks of daily 6x15 min ergometer training at submaximal intensity in addition to a 1 h/week group exercise session, followed by 5 months of home-based ergometer training of 30 min/day again in addition to a 1 h/week group exercise session or (ii) conventional therapy. All patients received a statin. Monocyte-bound cellular adhesion molecules LFA-1 (CD11a), MAC-1 (CD11b), VLA-4 (CD49d) and L-selectin (CD62L) were assessed by fluorescence activated cell sorting analysis.

RESULTS

After 4 weeks the multifactorial intervention led to a significant improvement of maximal work capacity, lipid profile, body mass index, blood pressure, fasting glucose and hemoglobin A1c. This was associated with a reduced expression of MAC-1 and VLA-4. After 5 months of a home-based intervention the beneficial effects of the cardiovascular risk profile were still apparent, whereas the effects on the expression of adhesion molecules were blunted.

CONCLUSION

In patients treated with statins, 4 weeks of high frequency and long duration exercise training led to a diminished expression of atherogenic adhesion molecules MAC-1 und VLA-4. After 5 months of home-based exercise training of moderate frequency and duration, these effects were blunted. Our data suggest that our patients in cardiac rehabilitation programs might further benefit from the antiatherogenic effects of an even higher amount of exercise training.

Exercise and diet induced weight loss improves measures of oxidative stress and insulin sensitivity in adults with characteristics of the metabolic syndrome

Obesity and insulin resistance (IR) increase the risk for coronary heart disease; however, much of this risk is not attributable to traditional risk factors. We sought to determine whether weight loss associated with supervised aerobic exercise beneficially alters biomarkers of oxidative stress and whether these alterations are associated with improvements in measures of insulin resistance. Twenty-five sedentary and overweight to obese [body mass index (BMI) = 33.0 +/- 0.8 kg/m(2)] individuals, with characteristics of the metabolic syndrome, participated in a 4- to 7-mo weight loss program that consisted of energy restriction (reduced by approximately 500 kcal/day) and supervised aerobic exercise (5 days/wk, 45 min/day at 60% Vo(2 max); approximately 375 kcal/day). IR and insulin sensitivity were assessed by the calculation of the homeostasis model assessment (HOMA) and quantitative insulin sensitivity check index (QUICKI), respectively. Oxidative stress was assessed by oxidized LDL (oxLDL), myeloperoxidase (MPO), and low- and high- density lipoprotein (LDL and HDL) lipid hydroperoxide concentrations in serum. Indexes for antioxidative status included apolipoprotein A1 (apoA1) concentrations and paraoxonase-1 (PON1) activity and protein concentrations. Exercise- and diet-induced weight loss ( approximately 10%) significantly (P < 0.05) increased insulin sensitivity and reduced IR, oxLDL, and LDL lipid hydroperoxides but did not alter HDL lipid hydroperoxides or MPO concentrations. Lifestyle modification impacted systemic antioxidative status by increasing apoA1 concentrations and reducing serum PON1 protein and activity. Changes in oxidative stress were not associated with alterations in HOMA or QUICKI. Diet- and exercise-induced weight loss ( approximately 10%) improves measures of insulin sensitivity and beneficially alters biomarkers of oxidative status.

In the absence of weight loss, exercise training does not improve adipokines or oxidative stress in overweight children

The aim of the present study was to examine the effect of exercise training on adipokines, inflammatory markers, and oxidative stress in overweight children. Nineteen overweight children were randomly assigned to an aerobic exercise training or sedentary control group for 8 weeks. Measurements included peak oxygen uptake (V o(2)max), body weight and composition, adipokines (C-reactive protein, interleukin 6, tumor necrosis factor alpha, adiponectin, leptin, and resistin), and oxidative stress (8-isoprostane). There were no differences between groups for change in body weight or composition over the 8 weeks. Exercise training improved V o(2)max (exercise group, 1.64 +/- 0.13 to 1.85 +/- 0.17L/min vs control group, 1.83 +/- 0.12 to 1.60 +/- 0.13 L/min, P < .05) but did not change any of the measured adipokines or the marker of systemic oxidative stress, 8-isoprostane. These data suggest that in the absence of weight loss, exercise training alone does not improve the adipokine profile or levels of oxidative stress in overweight children.

Dietary soya intake alters plasma antioxidant status and lipid peroxidation in postmenopausal women with the metabolic syndrome

Postmenopausal women with the metabolic syndrome are at high risk of oxidative stress. Several studies have suggested possible antioxidant properties of soya, but little evidence is available regarding the effect of soya on oxidative stress in postmenopausal women with the metabolic syndrome. The objective of the present study was to determine the effects of soya consumption on plasma total antioxidant capacity (TAC) and malondialdehyde (MDA) level in postmenopausal women with the metabolic syndrome. A randomised cross-over trial was undertaken on forty-two postmenopausal women with the metabolic syndrome. Participants were randomly assigned to consume a control (Dietary Approaches to Stop Hypertension; DASH) diet, a soya protein diet, or a soya nut diet, each for 8 weeks. Red meat in the DASH diet (one serving per d) was replaced by soya protein in the soya protein period and by soya nuts in the soya nut period. Significant differences between the end values of the control diet, soya protein diet and soya nut diet were seen for MDA (0.70, 0.64 and 0.63 mumol/l; global P < 0.01). The results also showed a significant difference between the end values for TAC (1950, 2030 and 2110 mumol/l, respectively; P < 0.01). The difference from control for TAC was +4.5 % (P < 0.01) in the soya nut period and +5.8 % (P < 0.01) in the soya protein regimen. Both soya nuts and soya protein decreased MDA significantly compared with the control diet (difference from control was - 7.9 % (P < 0.01) in the soya nut period and - 9.4 % (P < 0.01) in the soya protein diet). We conclude that soya consumption reduces plasma MDA and increases plasma TAC levels in postmenopausal women with the metabolic syndrome.

Obesity, inflammation, and insulin resistance

Weight gain and obesity are major risk factors for conditions and diseases ranging from insulin resistance and type 2 diabetes mellitus to atherosclerosis and the sequelae of nonalcoholic fatty liver disease. A chronic, subacute state of inflammation often accompanies the accumulation of excess lipid in adipose tissue and liver (hepatic steatosis), evidenced by changes in both inflammatory cells and biochemical markers of inflammation. These changes can be seen in the involved tissues and systemically, in terms of elevated circulating levels of inflammatory markers. The link between obesity and inflammation has therefore raised the important question of whether obesity-induced inflammation plays a pathogenic role in the development and progression of these disorders. We review the rapidly expanding body of animal and clinical data that support potential roles for inflammation in the pathogenesis of insulin resistance and type 2 diabetes mellitus.

Combined diet and exercise intervention reverses the metabolic syndrome in middle-aged males: results from the Oslo Diet and Exercise Study

We examined the single and combined effects of a 1-year diet and exercise intervention on the International Diabetes Federation (IDF) metabolic syndrome among middle-aged males. The study was a randomized, controlled, 2 x 2 factorial intervention study. Participants included 137 men with metabolic syndrome according to the IDF criteria aged 40-49 years randomly allocated to four intervention groups: diet alone (n=34), exercise alone (n=34), the combination of the diet and exercise intervention (n=43) or control (n=26). The main outcome measure was metabolic syndrome as defined by IDF criteria (2005). In the combined diet and exercise group, 14 participants (32.6%) (P<0.0001 as compared with control) had the metabolic syndrome after 1-year intervention. In the diet-only group, 22 participants (64.7%) (P=0.023 vs control) and in the exercise-only group 26 participants (76.5%) (P=0.23 vs control) had the metabolic syndrome following the intervention. Utilizing the factorial design, both dietary and exercise intervention had significant effects (P<0.005) on the resolution of the metabolic syndrome. Both exercise and dietary intervention reduced metabolic syndrome prevalence compared with control after 1 year of intervention. However, the combined diet and exercise intervention was significantly more effective than diet or exercise alone in the treatment of the metabolic syndrome.

Mechanisms of disease: oxidative stress and inflammation in the pathogenesis of hypertension

Animal studies have shown that oxidative stress and renal tubulointerstitial inflammation are associated with, and have major roles in, the pathogenesis of hypertension. This view is supported by the observations that alleviation of oxidative stress and renal tubulointerstitial inflammation reduce arterial pressure in animal models. Conversely, hypertension has been shown to cause oxidative stress and inflammation in renal and cardiovascular tissues in experimental animals. Taken together, these observations indicate that oxidative stress, inflammation and arterial hypertension participate in a self-perpetuating cycle which, if not interrupted, can lead to progressive cardiovascular disease and renal complications. These events usually occur in an insidious and asymptomatic manner over an extended period following the onset of hypertension. Severe target organ injury can, however, occasionally occur precipitously in the course of malignant or accelerated hypertension. Given the high degree of heterogeneity of hypertensive disorders, the factor(s) initiating the vicious cycle described vary considerably in different forms of hypertension. For instance, oxidative stress in the kidney and vascular tissue is the primary mediator in the pathogenesis of angiotensin-induced, and perhaps lead-induced, hypertension. By contrast, increased arterial pressure is probably the initiating trigger in salt-sensitive hypertension. Although the initiating factor might vary between hypertensive disorders, according to the proposed model, the three components of the cycle eventually coalesce in all forms of hypertension.

Insulin augments matrix metalloproteinase-9 expression in monocytes

OBJECTIVE

Insulin resistance and hyperinsulinemia are major causes of cardiovascular morbidity and mortality. Matrix metalloproteinases (MMPs), highly expressed in activated mononuclear cells in vulnerable atherosclerotic lesions, are the main proteolytic enzymes controlling plaque stability. The aim of this study was to investigate the regulation of monocyte MMP-9 by insulin.

METHODS AND RESULTS

Stimulation of MMP-9 expression by insulin was time- and concentration-dependent in human monocytic THP-1 cells. Inhibition of insulin receptor (IR) maturation via inhibition of its activating convertase furin with the pharmacological furin-inhibitor decanoyl-RVKR-chloromethylketone, as well as blocking of IGF-1R function with a IGF-1R blocking antibody, demonstrated that insulin mediates increases in MMP-9 via IR activation. Inhibition of insulin's "metabolic" phosphatidylinositol 3-kinase signaling with wortmannin (50 nmol/L) or LY294002 (2.5 micromol/L) did not prevent insulin-dependent MMP-9 induction. In contrast inhibition of insulin's "mitogenic" Ras-Raf-mitogen-activated protein kinase-kinase pathways with PD98059 (15 micromol/L) or U0126 (2 micromol/L) inhibited insulin-induced MMP-9 gelatinolytic activity in THP-1 cells. Likewise, PD98059 inhibited insulin augmented MMP-9 levels in primary human monocytes, whereas wortmannin had no effect.

CONCLUSION

This study demonstrates that insulin can induce MMP-9 via mitogenic signaling pathways in monocytes, whereas phosphatidylinositol 3-kinase-dependent signaling, typically altered in insulin resistance, is not required. Induction of MMP-9 by insulin may potentially contribute to a pro-inflammatory state and the increased cardiovascular morbidity and mortality in type 2 diabetics.

Peroxisome proliferator-activated receptors: Bridging metabolic syndrome with molecular nutrition

Over recent years, obesity rates and the onset of obesity-induced chronic diseases have risen dramatically. The more we learn about the physiological and morphological changes that occur during obesity, the more it is becoming clear that obesity-related disorders can be traced back to adipocyte hypertrophy and inflammation at white adipose tissue (WAT). To combat this problem, the body has developed a regulatory system specifically designed at mediating the systemic response to obesity, utilizing free fatty acids (FFAs) and their metabolites as nutrient messengers to signal adaptations from peripheral tissues. These messages are predominantly interceded through the peroxisome proliferator-activated receptors (PPARs), a family of ligand-induced transcription factors that serve as a net of lipid sensors throughout the body. Understanding how and why nutrients, nutrient derivatives and metabolites exert their physiological effects are the key goals in the study of molecular nutrition. By learning about the mechanisms and tissue-specific effects of endogenous PPAR ligands and expanding our knowledge of the body's integrated homeostatic system, we will significantly increase our odds of designing safe and effective preventive and therapeutic interventions that keep us one step ahead of obesity-related diseases.

Association of metabolic syndrome risk factors with selected markers of oxidative status and microinflammation in healthy omnivores and vegetarians

Conditions predisposing to metabolic syndrome (MetS) are associated with increased oxidative stress and inflammation. We studied, in vegetarians (n = 90) and omnivores (n = 46), the impact of the dietary regimen on the occurrence of MetS risk factors (RFs: BMI, blood pressure, glucose metabolism and lipid profile) in relation to oxidative status (advanced glycation end products (AGEs), advanced oxidation protein products (AOPPs), malondialdehyde, ferric reducing ability of plasma, vitamins A, E, C, beta-carotene and superoxide dismutase activity) and microinflammation (C-reactive protein, leukocytes and neopterin). The proportion of subjects without/positive for one or two MetS RFs was comparable between the groups. From the components of MetS only immunoreactive insulin levels differed significantly (95% CI: omnivores: 5.0-7.1 microU/mL, vegetarians: 4.5-5.4, p = 0.03). Omnivores had lower AOPP (omnivores: 0.29-0.36 micromol/g albumin, vegetarians: 0.36-0.52, p = 0.01) and beta-carotene levels than vegetarians, they consumed more calories, proteins, fat and saturated fatty acids, and less fibres, beta-carotene and vitamin C. Multiple regression analysis revealed vitamin E and AOPP levels as the most important independent determinants of MetS RFs. The vegetarian diet seems to exert beneficial effects on MetS RFs associated microinflammation. Whether the vegetarian diet may counteract the deleterious effects of elevated AOPPs and AGEs, remains to be elucidated.

Effect of a short-term diet and exercise intervention on inflammatory/anti-inflammatory properties of HDL in overweight/obese men with cardiovascular risk factors

There is significant debate regarding high-density lipoprotein cholesterol (HDL-C) and high-fiber, low-fat diets. The present study was designed to examine the effects of lifestyle modification on the inflammatory/anti-inflammatory properties of HDL in obese men (n = 22) with metabolic syndrome factors. Subjects were placed on a high-fiber, low-fat diet in a 3-wk residential program where food was provided ad libitum and daily aerobic exercise was performed. Fasting blood was drawn pre- and postintervention for serum lipids, lipid hydroperoxides, and the ability of subject HDL to alter low-density lipoprotein (LDL)-induced monocyte chemotactic activity (MCA) in a human artery wall coculture. Induction of MCA by control LDL in the absence of HDL was normalized to 1.0. Values >1.0 after HDL addition indicated proinflammatory HDL; values <1.0 indicated anti-inflammatory HDL. In addition, proteins involved in regulating HDL function, apolipoprotein A-I (apoA-I), paraoxonase 1 and 3, and platelet-activating factor acetylhydrolase were measured. After 3 wk, decreases in total-cholesterol, LDL-cholesterol, HDL-C, triglycerides, total cholesterol-to-HDL cholesterol ratio, and lipid hydroperoxides (all P < 0.05) were noted. The HDL inflammatory index decreased (P < 0.05) from pro- (1.14 +/- 0.11) to anti-inflammatory (0.94 +/- 0.09). ApoA-I level and paraoxonase activity did not change; however, platelet-activating factor acetylhydrolase activity increased (P < 0.05). Despite a quantitative reduction in HDL-C, HDL converted from pro- to anti-inflammatory. These data indicate that intensive lifestyle modification improves the function of HDL even in the face of reduced levels, suggesting increased turnover of proinflammatory HDL.

The metabolic syndrome: role of skeletal muscle metabolism

Skeletal muscle constitutes the largest insulin-sensitive tissue in the body and is the primary site for insulin-stimulated glucose utilization. Skeletal muscle resistance to insulin is fundamental to the metabolic dysregulation associated with obesity and physical inactivity, and contributes to the development of the metabolic syndrome (MS). The inability to efficiently take up and store fuel, and to transition from fat to glucose as the primary source of fuel during times of caloric abundance (high insulin) or scarcity (low insulin) has been termed metabolic inflexibility which contributes to a whole body metabolic dysregulation and cardiovascular risk. Potential mechanisms contributing to reduced insulin signaling and action in skeletal muscle includes adipose tissue expansion and increased inflammatory adipokines, increased renin-angiotensin-aldosterone system (RAAS) activity, decreases in muscle mitochondrial oxidative capacity, increased intramuscular lipid accumulation, and increased reactive oxygen species. Future research is focused upon understanding these and other potential mechanisms in order to identify therapeutic targets for reducing MS risk. Strategies will include adequate physical activity and maintaining a healthy weight, but may also require specific pharmacologic interventions.