Giovanni Giugliano

Inflammatory Cytokine Concentrations Are Acutely Increased by Hyperglycemia in Humans Role of Oxidative Stress

Background—Circulating levels of interleukin-6 (IL-6) and tumor necrosis factor-&agr; (TNF-&agr;) are elevated in diabetic patients. We assessed the role of glucose in the regulation of circulating levels of IL-6, TNF-&agr;, and interleukin-18 (IL-18) in subjects with normal or impaired glucose tolerance (IGT), as well as the effect of the antioxidant glutathione. Methods and Results—Plasma glucose levels were acutely raised in 20 control and 15 IGT subjects and maintained at 15 mmol/L for 5 hours while endogenous insulin secretion was blocked with octreotide. In control subjects, plasma IL-6, TNF-&agr;, and IL-18 levels rose (P <0.01) within 2 hours of the clamp and returned to basal values at 3 hours. In another study, the same subjects received 3 consecutive pulses of intravenous glucose (0.33 g/kg) separated by a 2-hour interval. Plasma cytokine levels obtained at 3, 4, and 5 hours were higher (P <0.05) than the corresponding values obtained during the clamp. The IGT subjects had fasting plasma IL-6 and TNF-&agr; levels higher (P <0.05) than those of control subjects. The increase in plasma cytokine levels during the clamping lasted longer (4 hours versus 2 hours, P <0.01) in the IGT subjects than in the control subjects, and the cytokine peaks of IGT subjects after the first glucose pulse were higher (P <0.05) than those of control subjects. On another occasion, 10 control and 8 IGT subjects received the same glucose pulses as above during an infusion of glutathione; plasma cytokine levels did not show any significant change from baseline after the 3 glucose pulses. Conclusions—Hyperglycemia acutely increases circulating cytokine concentrations by an oxidative mechanism, and this effect is more pronounced in subjects with IGT. This suggests a causal role for hyperglycemia in the immune activation of diabetes.

Postprandial endothelial activation in healthy subjects and in type 2 diabetic patients: role of fat and carbohydrate meals.

OBJECTIVES To compare the effect of a high-fat meal and a high-carbohydrate meal (pizza), with and without antioxidant vitamins, on endothelial activation in healthy subjects and in patients with type 2 diabetes mellitus. BACKGROUND The postprandial state is becoming increasingly acknowledged to affect some early events of atherogenesis. METHODS In a randomized, observer-blinded, crossover study, 20 newly diagnosed type 2 diabetic patients and 20 age- and gender-matched healthy subjects received two meals at one-week intervals: a high-fat meal (760 calories) and an isoenergetic high-carbohydrate meal (non-cheese pizza). In all subjects, the same meals were repeated immediately following ingestion of vitamin E, 800 IU, and ascorbic acid, 1,000 mg. RESULTS In normal subjects, the high-fat meal increased the plasma levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), which were prevented by vitamins. No change in these parameters occurred after pizza ingestion or pizza ingestion with vitamins. In diabetic patients, basal concentrations of glucose, cytokines and adhesion molecules were significantly higher than in nondiabetic controls. Both meals significantly increased cytokine and adhesion molecule levels, but the increase was more sustained following the high-fat meal. There was no significant change from baseline when vitamin supplementation accompanied each meal. There was a relationship between changes in serum triglycerides and changes in TNF-alpha (r = 0.39, p < 0.01), IL-6 (r = 0.28, p < 0.05) and VCAM-1 (r = 0.25, p < 0.05), and between changes in plasma glucose and changes in IL-6 (r = 0.36, p < 0.01) and ICAM-1 (r = 0.31, p < 0.02). CONCLUSIONS An oxidative mechanism mediates endothelial activation induced by post-meal hyperlipidemia and hyperglycemia.

Erectile dysfunction associates with endothelial dysfunction and raised proinflammatory cytokine levels in obese men

ABSTRACT. Erectile and endothelial dysfunction may have some shared pathways through a defect in nitric oxide activity. We evaluated associations between erectile function, endothelial function and markers of systemic vascular inflammation in 80 obese men, aged 35–55 yr, divided into two equal groups according to the presence/absence of erectile dysfunction. Compared with non-obese age-matched men [no.=50, body mass index (BMI)=24±1], obese men (all) had impaired indices of endothelial function as suggested by the reduced mean blood pressure and platelet aggregation responses to L-arginine, and higher circulating concentrations of the proinflammatory cytokines interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin- 18 (IL-18), as well as C-reactive protein (CRP). The mean erectile function score was 14±4 (range 7–19) in obese men with erectile dysfunction and 23.5±1 (range 22–25) in obese men without erectile dysfunction. Endothelial function showed a greater impairment in impotent obese men as compared with potent obese men. The mean blood pressure and platelet aggregation decreases following Larginine were -1.5±1.1 mmHg and -1.1±1.2%, respectively, in obese men with erectile dysfunction, and -3.4±1.2 mmHg and -5.6±2.1%, respectively, in obese men without erectile dysfunction (p<0.01). Circulating CRP levels were significantly higher in obese men with erectile dysfunction as compared with obese men without erectile dysfunction (p<0.05). Erectile function score was positively associated with mean blood pressure responses to L-arginine and negatively associated with BMI, waist-to-hip ratio (WHR), and CRP. Erectile and endothelial dysfunction associate in obese men and may contribute to their raised cardiovascular risk through impaired nitric oxide availability elicited by a low-grade inflammatory state.

Effects of Intensive Lifestyle Changes on Erectile Dysfunction in Men

INTRODUCTION Limited data are available supporting the notion that treatment of lifestyle risk factors may improve erectile dysfunction (ED). AIM In the present study, we analyzed the effect of a program of changing in lifestyle designed to improve erectile function in subjects with ED or at increasing risk for ED. METHODS Men were identified in our database of subjects participating in randomized controlled trials evaluating the effect of lifestyle changes. A total of 209 subjects were randomly assigned to one of the two treatment groups. The 104 men randomly assigned to the intervention program received detailed advice about how to reduce body weight, improve quality of diet, and increase physical activity. The 105 subjects in the control group were given general information about healthy food choices and general guidance on increasing their level of physical activity. MAIN OUTCOME MEASURES Changes in erectile function score (International Index of Erectile Function-5 [IIEF-5]; items 5, 15, 4, 2, and 7 from the full-scale IIEF-15) and dependence of the restoration of erectile function on the changes in lifestyle that were achieved. RESULTS Erectile function score improved in the intervention group. At baseline, 35 subjects in the intervention group and 38 subjects in the control group had normal erectile function (34% and 36%, respectively). After 2 years, these figures were 58 subjects in the intervention group and 40 subjects in the control group, respectively (56% and 38%, P = 0.015). There was a strong correlation between the success score and restoration of erectile function. CONCLUSIONS It is possible to achieve an improvement of erectile function in men at risk by means of nonpharmacological intervention aiming at weight loss and increasing physical activity.

Role of adipokines in the obesity-inflammation relationship: the effect of fat removal.

Summary: During the past 10 years, there has been a dramatic increase in the prevalence of obesity in the United States and other developed nations. Recent studies indicate that adipose tissue is an endocrine organ producing numerous proteins, collectively referred to as adipokines, with broad biological activity, that play an important autocrine role in obesity-associated complications. Adipose tissue in general and visceral fat in particular are thought to be key regulators of inflammation. Inflammation is heavily involved in the onset and development of atherothrombotic disease. Moreover, chronic inflammation may also represent a triggering factor in the origin of the metabolic syndrome and type 2 diabetes mellitus. According to a hypothesis, stimuli such as overnutrition, physical inactivity, and aging would result in cytokine hypersecretion and eventually lead to insulin resistance and diabetes in genetically or metabolically predisposed individuals. This article discusses the current understanding of important adipokines thought to be involved in the metabolic and cardiovascular risk associated with obesity. Available evidence linking fat removal by liposuction to modification of cardiovascular risk and vascular inflammatory markers in the obese patient is also presented. Most studies have shown that liposuction produces beneficial effects on insulin resistance and vascular inflammation in the obese patient, reducing its cardiovascular risk. Besides having a significant role in body contouring of the obese patient at the end of the lengthy process of bariatric surgery and massive weight loss, plastic surgery should be incorporated into a multifaceted program of lifestyle changes that allows the obese patient to obtain weight loss and, more importantly, to maintain the reduced weight in the long term.

Effect of a multidisciplinary program of weight reduction on endothelial functions in obese women

Obesity is associated with an increased risk of developing atherosclerosis and atherosclerotic lesions are essentially an inflammatory response. The aim of this study was to evaluate the effect of a medically supervised, multidisciplinary weight loss program on endothelial functions and circulating levels of proinflammatory cytokines in obese women. Twenty healthy pre-menopausal obese women and 20 age-matched normal weight women were studied. Endothelial functions were assessed by evaluating the response of blood pressure and platelet aggregation to an intravenous bolus of L-arginine (3 g), the natural precursor of nitric oxide. In obese women, the vascular and rheological responses to L-arginine were significantly lower (p<0.05) at baseline, as compared with non-obese women, indicating endothelial dysfunction; on the contrary, basal concentrations of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were significantly higher (p<0.01). After one year of a multi-disciplinary program of weight reduction consisting of diet, exercise and liposuction surgery, all obese women lost at least 10% of their original weight (10.5±1.7 kg, range 7.9–13.9 kg). Compared with baseline, sustained weight loss was associated with reduction of cytokine (p<0.01) concentrations and with improvement of vascular responses to L-arginine. In conclusion, a multidisciplinary approach aimed at inducing a sustained reduction of body weight in obese women is feasible and is associated with improvement of endothelial functions and reduction of circulating proinflammatory cytokine concentrations.

Elevated plasma free fatty acid concentrations do not modify cardiac repolarization in patients treated by electrolyte-glucose-insulin infusion.

Fat emulsion infusion is routinely used as a source of calories and essential fatty acids for critically ill patients who may be at risk for acquired ventricular repolarization alterations due either to drugs or electrolyte disturbances. The aim of this study was to evaluate whether acute elevations of plasma free fatty acid concentrations influence the corrected Q-T interval (Q-Tc), Q-Tc dispersion and sympathetic nervous system activity in patients requiring parenteral nutrition. Thirty hospitalized patients (mean±SD: 62±17 yr of age) requiring total parenteral nutrition received an infusion of 10% (500 ml) triacylglycerol emulsion as a source of calories (450 Kcal); on another occasion, and in random order, the same patients received an infusion of 20% (500 ml) triacylglycerol emulsion (900 Kcal). The infusion lasted 8 h and was preceded by a sc injection of heparin (5000 U). Infusions of both 10% and 20% triacylglycerol emulsion increased plasma free fatty acid (p<0.001) and triacylglycerol (p<0.01) concentrations, and was associated with no significant change in mean BP, heart rate, and plasma catecholamines. At baseline, Q-Tc and Q-Tc dispersion were within the normal range (<440 milliseconds for QTc and <40 ms for QTc-d) and did not show any significant change at any time during infusion of triacylglycerol emulsion at both concentrations. In the setting of a balanced parenteral nutrition, acute elevation of plasma free fatty acid concentrations in critically ill patients do not modify ventricular repolarization.

Interleukin-20 circulating levels in obese women: Effect of weight loss

BACKGROUND AND AIMS Obesity is associated with an increased risk of developing atherosclerosis. Interleukin-20 (IL-20) is a pleiotropic cytokine thought to be involved in the onset and progression of atherosclerosis. The aim of this study was to determine whether circulating levels of IL-20 are elevated in obese women and whether they could be affected by a substantial decrease in body weight. METHODS AND RESULTS Fifty obese and 50 age-matched, normal weight, premenopausal women participated in the study. Obese women entered into a medically supervised weight loss program aimed at reducing body weight to 90% of baseline. We measured anthropometric, glucose and lipid parameters, and IL-20, C-Reactive Protein (CRP) and interleukin-10 (IL-10) circulating levels. Circulating IL-20 and CRP levels were significantly higher in obese than control women (P=0.01), while IL-10 levels were significantly lower; IL-20 levels were positively associated with body weight (r=0.35; P=0.02) and visceral fat (waist-hip ratio; r=0.32; P=0.025). Caloric restriction-induced weight loss (>10% of original weight) over 6 months reduced IL-20 levels from 152 (112/184) to 134 (125/153)pg/ml (median and 25%/75%; P=0.03), and it was positively associated with changes in body mass index and waist-hip ratio. CONCLUSION In premenopausal obese women, IL-20 levels are higher than matched normal weight control women, are associated with body weight and waist-hip ratio, and are reduced by weight loss.