Vasoactive mediators of hypertension in obesity.

Obesity is associated with hypertension. However, the mechanisms involved are not fully understood. Therefore, we investigated the relationship between obesity and vasoactive mediators. In this cross-sectional study, blood pressure (BP) and vasoactive mediators of hypertension are compared among 135 adults in the nonobese, obese, and morbidly obese body mass index (BMI) ranges (BMI ≤27, 30-40, and >40 kg/m2, respectively). Angiotensinogen, angiotensin II, renin, aldosterone, endothelin-1 (ET-1), neprilysin, atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), cyclic guanosine monophosphate (cGMP), and cyclic adenosine monophosphate (cAMP) levels were measured and their relationship to BP, BMI, race, and gender were investigated. Systolic and diastolic BP (SBP and DSP) were significantly higher in subjects with obesity and morbid obesity compared with nonobese. Angiotensin II, ET-1, and neprilysin were significantly higher in subjects with morbid obesity while BNP was lower. Levels of angiotensinogen, renin, aldosterone, ANP, cGMP, and cAMP did not differ between the groups. BMI was positively related to SBP, DBP, angiotensin II, ET-1, and neprilysin, and inversely related to cGMP and BNP. Age, male gender, and African-American race were associated with higher SBP. SBP was positively related to angiotensin II and ET-1 and inversely related to aldosterone, renin, and cGMP. On multivariate analyses, age, BMI, gender, and race were the main determinants of SBP, and excluding these variables, angiotensin II, aldosterone, renin, and ET-1 accounted for 21.1% ability to predict SBP. Obesity, especially morbid obesity, is associated with higher BP, higher angiotensin II and ET-1 (vasoconstrictors), and lower levels BNP and cGMP (vasodilators). SBP variability can be partly explained by angiotensin II, aldosterone, renin, and ET-1.NEW & NOTEWORTHY Our data show that obesity, especially morbid obesity, is associated with higher blood pressure levels and increases angiotensin II and endotherlin-1 (ET-1) (vasoconstrictors) and lower levels BNP and cGMP (vasodilators) and that systolic blood pressure variability can be partly explained by levels of angiotensin II, aldosterone, renin, and ET-1. The effect of these mediators on blood pressure is in addition to the effects of other known factors related to age, male gender, and AA race.

Dapagliflozin reduces systolic blood pressure and modulates vasoactive factors.

AIM: To investigate the mechanisms underlying improvements in blood pressure (BP) and congestive heart failure outcomes following treatment with dapagliflozin, a sodium-glucose co-transporter-2 inhibitor. RESEARCH DESIGN AND METHODS: A total of 52 patients with type 2 diabetes (T2D) with an HbA1c of less than 8% participated in this prospective, double-blind and placebo-controlled study. Patients were randomized (1:1) to either dapagliflozin 10 mg daily or placebo for 12 weeks. Half the patients were also monitored for 6 h following their first dose for acute effects on BP. Blood and urine samples were collected and levels of angiotensinogen, angiotensin II, renin, aldosterone, endothelin-1, atrial natriuretic peptide (ANP), brain natriuretic peptide, cyclic adenosine monophosphate, cyclic guanosine monophosphate (cGMP) and neprilysin were measured. The expression of angiotensin-converting enzyme, guanylate cyclase and phosphodiesterase 5 (PDE5) was measured in circulating mononuclear cells (MNC). RESULTS: A total of 24 and 23 patients receiving dapagliflozin and placebo, respectively, completed the 12-week study. Systolic BP decreased significantly, compared with placebo, both after single-dose (by 7 ± 3 mmHg) and 12-week (by 7 ± 2 mmHg) treatment with dapagliflozin. Dapagliflozin suppressed angiotensin II and angiotensinogen (by 10.5 ± 2.1 and 1.45 ± 0.42 µg/mL, respectively) and increased ANP and cGMP (by 34 ± 11 and 29 ± 11 pmol/mL, respectively) compared with the placebo group. cGMP levels also increased acutely following a single dose of dapagliflozin. Dapagliflozin also suppressed PDE5 expression by 26% ± 11% in MNC. There were no changes observed in the other vasoactive mediators investigated. CONCLUSIONS: Dapagliflozin administration in T2D resulted in both acute and chronic reduction in systolic BP, a reduction in vasoconstrictors and an increase in vasodilators. These changes may potentially contribute to its antihypertensive effects and its benefits in congestive cardiac failure.

Liraglutide treatment in overweight and obese patients with type 1 diabetes: A 26-week randomized controlled trial; mechanisms of weight loss.

AIM: To investigate the effects of liraglutide treatment on glycaemic control and adipose tissue metabolism in overweight and obese people with type 1 diabetes (T1DM). RESEARCH DESIGN AND METHODS: A total of 84 adult overweight and obese patients with T1DM, with no detectable C-peptide, were randomized (1:1) to either placebo or 1.8 mg/d liraglutide for 6 months. Blood samples were collected at 0, 12 and 26 weeks. Subcutaneous adipose tissue biopsies, a high-calorie high-fat meal challenge test, continuous glucose monitoring, dual-energy X-ray absorptiometry and MRI were performed before and at the end of treatment. RESULTS: In all, 37 and 27 patients who received liraglutide and placebo, respectively, completed the study. Glycated haemoglobin fell by 0.41 ± 0.18% (4.5±1.4 mmol/mol) from baseline after liraglutide treatment (P = 0.001), and by 0.29 ± 0.19% (3.1±2.0 mmol/mol) compared to placebo (P = 0.1). There was no increase in hypoglycaemia, while the time spent in normal glycaemia increased (P = 0.015) and time spent in hyperglycaemia decreased (P = 0.019). Body weight fell significantly in the liraglutide group, mostly in the form of fat mass loss (including visceral fat), with no change in lean mass. Systolic blood pressure (SBP) also fell after liraglutide treatment. Liraglutide also caused a significant increase in the expression of adipose tissue triglyceride lipase, carnitine palmitoyl transferase-1, peroxisome proliferator-activated receptor (PPAR)α, PPARδ, uncoupling protein-2 and type 2 iodothyronine deiodinase in the adipose tissue. CONCLUSIONS: Liraglutide improves glycaemia, reduces adiposity and SBP. Liraglutide also stimulates mechanisms involved with an increase in lipid oxidation and thermogenesis, while conserving lean body mass.

Decreases in neprilysin and vasoconstrictors and increases in vasodilators following bariatric surgery.

The aim of this study was to determine if weight loss following Roux-en-Y gastric bypass (RYGB) surgery in morbidly obese patients is associated with a decrease in plasma concentrations of neprilysin, mediators of the renin angiotensin system (RAS), catecholamines and endothelin-1, and also with an increase in the concentrations of vasodilators. Fasting blood samples were obtained from 15 patients with morbid obesity and diabetes prior to and 6 months after RYGB surgery. Circulating levels of neprilysin, vasoconstrictors, vasodilators, and the mRNA expression of related genes in circulating mononuclear cells (MNC) were measured. Six months after RYGB surgery the concentrations of neprilysin, angiotensinogen, angiotensin II, renin and endothelin-1 fell significantly by 27 ±16%, 22 ±10%, 22 ±8%, 35 ±13% and 17 ±6% (P < .05 for all), respectively, while ANP concentrations increased significantly by 24 ±13%. There was no significant change in aldosterone, BNP, cAMP or cGMP concentrations, or angiotensin converting enzyme (ACE) expression. These changes may contribute to the reduction of congestive cardiac failure and blood pressure risks after RYGB surgery.

Exenatide induces an increase in vasodilatory and a decrease in vasoconstrictive mediators.

In view of the known vasodilatory effects of glucagon-like peptide-1 and exenatide, we investigated the effects of exenatide on vasoactive factors. We analysed blood samples and mononuclear cells (MNCs) from a previous study, collected after a single dose and 12 weeks of exenatide or placebo treatment in a series of 24 patients with type 2 diabetes mellitus. After exenatide treatment, plasma concentrations of atrial natriuretic peptide, cyclic guanyl monophosphate (cGMP) and cyclic adenyl monophosphate increased significantly at 12 weeks. Plasma cGMP and adenylate cyclase expression in MNCs increased significantly after a single dose. Angiotensinogen concentration fell significantly 2 hours after a single dose and at 12 weeks, while renin and angiotensin II levels fell significantly only after a single dose and not after 12 weeks of treatment. Exenatide also suppressed the plasma concentration of transforming growth factor-ß and the expression of P311 in MNCs at 12 weeks. Thus, exenatide induces an increase in a series of vasodilators, while suppressing the renin-angiotensin system. These changes may contribute to the overall vasodilatory effect of exenatide.

Liraglutide acutely suppresses glucagon, lipolysis and ketogenesis in type 1 diabetes.

In view of the occurrence of diabetic ketoacidosis associated with the use of sodium-glucose transport protein-2 inhibitors in patients with type 1 diabetes (T1DM) and the relative absence of this complication in patients treated with liraglutide in spite of reductions in insulin doses, we investigated the effect of liraglutide on ketogenesis. Twenty-six patients with inadequately controlled T1DM were randomly divided into 2 groups of 13 patients each. After an overnight fast, patients were injected, subcutaneously, with either liraglutide 1.8 mg or with placebo. They were maintained on their basal insulin infusion and were followed up in our clinical research unit for 5 hours. The patients injected with placebo maintained their glucose and glucagon concentrations without an increase, but there was a significant increase in free fatty acids (FFA), acetoacetate and ß-hydoxybutyrate concentrations. In contrast, liraglutide significantly reduced the increase in FFA, and totally prevented the increase in acetoacetate and ß-hydroxybutyrate concentrations while suppressing glucagon and ghrelin concentrations. Thus, a single dose of liraglutide is acutely inhibitory to ketogenesis.

Effect of testosterone on hepcidin, ferroportin, ferritin and iron binding capacity in patients with hypogonadotropic hypogonadism and type 2 diabetes.

CONTEXT: As the syndrome of hypogonadotropic hypogonadism (HH) is associated with anaemia and the administration of testosterone restores haematocrit to normal, we investigated the potential underlying mechanisms. DESIGN: Randomized, double-blind, placebo-controlled trial. METHODS: We measured basal serum concentrations of erythropoietin, iron, iron binding capacity, transferrin (saturated and unsaturated), ferritin and hepcidin and the expression of ferroportin and transferrin receptor (TR) in peripheral blood mononuclear cells (MNC) of 94 men with type 2 diabetes. Forty-four men had HH (defined as subnormal free testosterone along with low or normal LH concentrations) while 50 were eugonadal. Men with HH were randomized to testosterone or placebo treatment every 2 weeks for 15 weeks. Blood samples were collected at baseline, 3 and 15 weeks after starting treatment. Twenty men in testosterone group and 14 men in placebo group completed the study. RESULTS: Haematocrit levels were lower in men with HH (41·1 ± 3·9% vs 43·8 ± 3·4%, P = 0·001). There were no differences in plasma concentrations of hepcidin, ferritin, erythropoietin, transferrin or iron, or in the expression of ferroportin or TR in MNC among HH and eugonadal men. Haematocrit increased to 45·3 ± 4·5%, hepcidin decreased by 28 ± 7% and erythropoietin increased by 21 ± 7% after testosterone therapy (P < 0·05). There was no significant change in ferritin concentrations, but transferrin concentration increased while transferrin saturation and iron concentrations decreased (P < 0·05). Ferroportin and TR mRNA expression in MNC increased by 70 ± 13% and 43 ± 10%, respectively (P < 0·01), after testosterone therapy. CONCLUSIONS: The increase in haematocrit following testosterone therapy is associated with an increase in erythropoietin, the suppression of hepcidin, and an increase in the expression of ferroportin and TR.

Decreased insulin secretion and incretin concentrations and increased glucagon concentrations after a high-fat meal when compared with a high-fruit and -fiber meal.

This study was conducted to investigate whether a high-fat/high-carbohydrate (HFHC) meal induces an increase in plasma concentrations of glucagon, dipeptidyl peptidase-IV (DPP-IV), and CD26 expression in mononuclear cells (MNC) while reducing insulin, C-peptide, proinsulin, GIP, and GLP-1 concentrations. Ten healthy normal subjects were given either a 910-calorie HFHC meal or an American Heart Association (AHA) meal rich in fruit and fiber during the first visit and the other meal during the second visit in crossover design. Blood samples were collected at baseline and at 15, 30, 45, 60, 75, 90, 120, 180, and 300 min following the meal. There was a significantly greater increase in glucose concentrations and lower increase in postprandial insulin, C-peptide, and proinsulin concentrations and lower insulin/glucose ratios following the HFHC meal. HFHC meal intake induced marked increases in plasma glucagon and DPP-IV concentrations and an increase in CD26 mRNA expression in MNC compared with the AHA meal. In addition, the HFHC meal induced a reduction in GIP and peak GLP-1 secretion compared with the AHA meal. This was associated with a significantly greater increase in oxidative stress and proinflammatory mediators including, ROS generation, TNFα, and IL-1ß mRNA expression and plasma concentrations of TBARS, FFA, and LPS. We conclude that the proinflammatory HFHC meals result in lower insulin, C-peptide, proinsulin, and GIP secretion in association with higher plasma glucagon and DPP-IV concentrations and CD26 expression in MNC compared with the AHA meal.

Insulin infusion suppresses while glucose infusion induces Toll-like receptors and high-mobility group-B1 protein expression in mononuclear cells of type 1 diabetes patients.

The purpose of this study was to determine whether an insulin infusion exerts an anti-inflammatory effect and whether the infusion of small amounts of glucose results in oxidative and inflammatory stress in patients with type 1 diabetes. Ten patients with type 1 diabetes were infused with either 2 U/h of insulin with 100 ml 5% dextrose/h to or just dextrose (100 ml/h) or physiological saline (100 ml/h) for 4 h after an overnight fast on three separate days. Blood samples were collected at 0, 2, 4, and 6 h. Insulin with glucose infusion led to the maintenance of euglycemia and a significant suppression of reactive oxygen species (ROS) generation, p47(phox) expression, Toll-like receptor (TLR)-4, TLR-2, TLR-1, CD14, high-mobility group-B1 (HMGB1), p38 mitogen-activated protein (MAP) kinase, c-Jun NH2-terminal kinase (JNK)-1, and platelet/endothelial cell adhesion molecule expression and a fall in serum concentrations of C-reactive protein, HMGB1, and rapid upon activation T cell expressed and secreted. Glucose infusion led to an increase in plasma glucose concentration from 115 (fasting) to 215 (at 4 and 6 h) mg/dl and to an increase in ROS generation, the expression of TLR-4, TLR-2, TLR-1, HMGB1, p38 MAP kinase, and JNK-1, and plasma concentrations of HMGB1. While insulin reduces indexes of oxidative and inflammatory stress in patients with type 1 diabetes, even small amounts of glucose (20 g over 4 h) induce oxidative and inflammatory stress. These effects are reflected in TLR, p38 MAP kinase, and HMGB1 expression. The induction of significant oxidative and inflammatory stress by small amounts of glucose in patients with type 1 diabetes may have important pathophysiological and therapeutic implications.

Testosterone Increases the Expression and Phosphorylation of AMP Kinase α in Men With Hypogonadism and Type 2 Diabetes.

CONTEXT: Adenosine 5'-monophosphate-activated protein kinase-α (AMPKα) is a mediator of exercise-induced glucose uptake in skeletal muscle. OBJECTIVE: We evaluated whether AMPKα expression and phosphorylation are reduced in skeletal muscle and adipose tissue of patients with hypogonadotropic hypogonadism (HH), and whether testosterone replacement therapy results in restoration of the expression and phosphorylation of AMPKα. DESIGN: This is a secondary analysis of a previously completed trial that showed an insulin-sensitizing effect of testosterone therapy in men with type 2 diabetes and HH. SETTING: Clinical research center at university. PATIENTS: Thirty-two men with HH and 32 eugonadal men were compared at baseline. INTERVENTIONS: Men with HH were treated with intramuscular injections of testosterone or placebo every 2 weeks for 22 weeks. Quadriceps muscle biopsies and subcutaneous abdominal fat biopsies were obtained before and after 4-hour euglycemic hyperinsulinemic clamp, prior to and after testosterone or placebo therapy. OUTCOME MEASURES AND RESULTS: mRNA expression of AMPKα in hypogonadal men was lower by 37% in adipose tissue and 29% in skeletal muscle, respectively, compared with levels in eugonadal men, while phosphorylated AMPKα was lower by 22% and 28%, respectively. Following testosterone replacement, the expression of AMPKα did not alter in the fasting state but increased markedly by 41% and 46% in adipose tissue and muscle, respectively, after the clamp. In contrast, phosphorylated AMPKα increased by 69% in muscle after testosterone therapy but did not change following the clamp. CONCLUSIONS: Testosterone modulates the expression of AMPKα and phosphorylated AMPKα. These effects may contribute to the improved insulin sensitivity following testosterone therapy.

Dapagliflozin Suppresses Hepcidin And Increases Erythropoiesis.

CONTEXT: Dapagliflozin and other SGLT2 inhibitors are known to increase hematocrit, possibly due to its diuretic effects and hemoconcentration. OBJECTIVE: Since type 2 diabetes is a proinflammatory state and since hepcidin, a known suppressor of erythropoiesis, is increased in proinflammatory states, we investigated the possibility that dapagliflozin suppresses hepcidin concentrations and thus increases erythropoiesis. DESIGN: Prospective, randomized, and placebo-controlled study. SETTING: Single endocrinology center. PATIENTS: Fifty-two obese type 2 diabetes patients. INTERVENTION: Patients were randomized (1:1) to either dapagliflozin (10 mg daily) or placebo for 12 weeks. Blood samples were collected before and after treatments and serum, plasma, and mononuclear cells (MNC) were prepared. MAIN OUTCOME MEASURE: Hepcidin and other hematopoietic factors. RESULTS: Following dapagliflozin treatment, there was a significant fall in HbA1c and a significant increase in hemoglobin concentration and hematocrit. Dapagliflozin treatment significantly reduced circulating hepcidin and ferritin concentrations while causing a significant increase in levels of the hepcidin inhibitor, erythroferrone, and a transient increase in erythropoietin. Additionally, dapagliflozin increased plasma transferrin levels and expression of transferrin receptors 1 and 2 in MNC, while there was no change in the expression of the iron cellular transporter, ferroportin. Dapagliflozin treatment also caused a decrease in hypoxia-induced factor-1α expression in MNC while it increased the expression of its inhibitor, prolyl hydroxylase-2. There were no significant changes in any of these indices in the placebo group. CONCLUSIONS: We conclude that dapagliflozin increases erythropoiesis and hematocrit through mechanisms that involve the suppression of hepcidin and the modulation of other iron regulatory proteins.

Increase in Osteocalcin Following Testosterone Therapy in Men With Type 2 Diabetes and Subnormal Free Testosterone.

CONTEXT: One-third of men with type 2 diabetes have subnormal free testosterone concentrations. We evaluated the following: (i) whether bone mineral density (BMD) and bone strength are affected by gonadal status in type 2 diabetes and (ii) the effect of testosterone replacement on markers of osteoblast and osteoclast activity. DESIGN: This is a secondary analysis of a previously completed, randomized, placebo-controlled trial. Ninety-four men with type 2 diabetes were recruited; 44 had subnormal free testosterone concentrations. Men with subnormal free testosterone concentrations were randomized to receive intramuscular injections of testosterone or placebo every 2 weeks for 22 weeks. Dual energy X-ray absorptiometry scans were performed at baseline and at 23 weeks. RESULTS: Men with subnormal free testosterone had similar BMD compared with men with normal free testosterone. However, bone strength indices were lower in men with subnormal free testosterone. BMD was related to free estradiol concentrations (r = 0.37, P = 0.004 at hip), whereas bone strength was related to free testosterone concentrations (r = 0.41, P < 0.001). Testosterone replacement increased osteocalcin concentrations [mean change (95% CI), 3.52 (0.45, 6.59), P = 0.008]. C-Terminal telopeptide (CTx) concentrations also increased at 15 weeks but reverted to baseline following that. There were no changes in other bone turnover markers or BMD. CONCLUSION: We conclude that testosterone replacement resulted in an increase in osteocalcin and a transient increase in CTx, indicating an increase in osteoblastic activity and transient increase in bone breakdown. Therefore, a major action of testosterone is to increase bone turnover in men with type 2 diabetes.

Acute effects of insulin on skeletal muscle growth and differentiation genes in men with type 2 diabetes.

AIMS: Insulin has anabolic effects on skeletal muscle. However, there is limited understanding of the molecular mechanisms underlying this effect in humans. We evaluated whether the skeletal muscle expression of satellite cell activator fibroblast growth factor 2 (FGF2) and muscle growth and differentiation factors are modulated acutely by insulin during euglycemic-hyperinsulinemic clamp (EHC). DESIGN AND METHODS: This is a secondary investigation and analysis of samples obtained from a previously completed trial investigating the effect of testosterone replacement in males with hypogonadotropic hypogonadism and type 2 diabetes. Twenty men with type 2 diabetes underwent quadriceps muscle biopsies before and after 4 h of EHC. RESULTS: The infusion of insulin during EHC raised the expression of myogenic growth factors, myogenin (by 72 ± 20%) and myogenin differentiation protein (MyoD; by 81 ± 22%). Insulin reduced the expression of muscle hypertrophy suppressor, myogenic regulatory factor 4 (MRF4) by 34 ± 14%. In addition, there was an increase in expression of FGF receptor 2, but not FGF2, following EHC. The expression of myostatin did not change. CONCLUSIONS: Insulin has an acute potent effect on expression of genes that can stimulate muscle differentiation and growth.

Effect of Testosterone on FGF2, MRF4, and Myostatin in Hypogonadotropic Hypogonadism: Relevance to Muscle Growth.

CONTEXT: Fibroblast growth factor (FGF)2 is an important stimulatory modulator of satellite cells in skeletal muscle. Satellite cells play a cardinal role in muscle growth and repair. OBJECTIVE: We evaluated whether skeletal muscle expression of FGF2 and muscle growth and differentiation factors are reduced in patients with hypogonadotropic hypogonadism (HH) and whether testosterone replacement therapy results in their restoration. DESIGN: This is a secondary analysis of a previously completed trial of testosterone replacement in men with type 2 diabetes and HH. SETTING: Clinical Research Center at a university. PATIENTS: Twenty-two men with HH and 20 eugonadal men were compared at baseline. INTERVENTIONS: Twelve men with HH were treated with intramuscular injections of 250 mg testosterone every 2 weeks for 22 weeks, and 10 men received placebo injections. Quadriceps muscle biopsies and blood samples were obtained before and after testosterone therapy. OUTCOME MEASURES AND RESULTS: The expression of FGF2 and FGF receptor (FGFR)2 in skeletal muscle of men with HH was significantly lower than that in eugonadal men by 57% and 39%, respectively (P < 0.05). After 22 weeks of testosterone, the expression of FGF2 increased, whereas that of myogenic regulatory factor (MRF)4 and myostatin decreased significantly. There was no change in expression of FGFR2, myogenin, or myogenic differentiation protein in the skeletal muscle. Plasma FGF2 and IGF-1 concentrations increased after testosterone therapy. CONCLUSIONS: These data show that testosterone is a major modulator of FGF2, MRF4, and myostatin expression in skeletal muscle. These effects may contribute to the increase in muscle mass after testosterone therapy.

Exenatide Increases IL-1RA Concentration and Induces Nrf-2‒Keap-1‒Regulated Antioxidant Enzymes: Relevance to ß-Cell Function.

Purpose: We previously demonstrated the anti-inflammatory and antioxidant effects of exenatide. We now hypothesized that exenatide also increases the plasma concentration of interleukin-1 receptor antagonist (IL-1RA), an endogenous anti-inflammatory protein, and modulates the nuclear factor erythroid 2‒related factor‒Kelchlike ECH-associated protein 1‒antioxidant response element (Nrf-2‒Keap-1‒ARE) system to induce key antioxidant enzymes to suppress inflammatory and oxidative stress. Methods: Twenty-four patients with obesity and type 2 diabetes receiving combined oral and insulin therapy were randomly assigned to receive either exenatide 10 µg or placebo twice a day for 12 weeks. Results: Exenatide increased IL-1RA concentration by 61% (from 318 ± 53 to 456 ± 88 pg/mL; P < 0.05). Exenatide treatment also suppressed Keap-1 protein (P < 0.05) and increased messenger RNA expression of NQO-1, glutathione S-transferase PI, heme oxygenase-1, and p21 and increased NAD(P)H dehydrogenase [quinone] 1 protein (P < 0.05) in mononuclear cells. Conclusions: Because IL-1RA protects, maintains, and stimulates ß-cell function in humans and Nrf-2‒Keap-1‒ARE protects ß cells in animals with experimental diabetes, these actions of exenatide may contribute to a potential protective effect on ß cells in diabetes.

Diminished androgen and estrogen receptors and aromatase levels in hypogonadal diabetic men: reversal with testosterone.

AIMS: One-third of males with type 2 diabetes (T2DM) have hypogonadism, characterized by low total and free testosterone concentrations. We hypothesized that this condition is associated with a compensatory increase in the expression of androgen receptors (AR) and that testosterone replacement reverses these changes. We also measured estrogen receptor and aromatase expression. MATERIALS AND METHODS: This is a randomized double-blind placebo-controlled trial. Thirty-two hypogonadal and 32 eugonadal men with T2DM were recruited. Hypogonadal men were randomized to receive intramuscular testosterone or saline every 2 weeks for 22 weeks. We measured AR, ERα and aromatase expression in peripheral blood mononuclear cells (MNC), adipose tissue and skeletal muscle in hypogonadal and eugonadal males with T2DM at baseline and after 22 weeks of treatment in those with hypogonadism. RESULTS: The mRNA expression of AR, ERα (ESR1) and aromatase in adipose tissue from hypogonadal men was significantly lower as compared to eugonadal men, and it increased significantly to levels comparable to those in eugonadal patients with T2DM following testosterone treatment. AR mRNA expression was also significantly lower in MNC from hypogonadal patients compared to eugonadal T2DM patients. Testosterone administration in hypogonadal patients also restored AR mRNA and nuclear extract protein levels from MNC to that in eugonadal patients. In the skeletal muscle, AR mRNA and protein expression are lower in men with hypogonadism. Testosterone treatment restored AR expression levels to that comparable to levels in eugonadal men. CONCLUSIONS: We conclude that, contrary to our hypothesis, the expression of AR, ERα and aromatase is significantly diminished in hypogonadal men as compared to eugonadal men with type 2 diabetes. Following testosterone replacement, there is a reversal of these deficits.

Antiinflammatory and ROS Suppressive Effects of the Addition of Fiber to a High-Fat High-Calorie Meal.

Background: Fiber intake is associated with a reduction in the occurrence of cardiovascular events and diabetes. Objective: To investigate whether the addition of fiber to a high-fat, high-calorie (HFHC) meal prevents proinflammatory changes induced by the HFHC meal. Design: Ten normal fasting subjects consumed an HFHC meal with or without an additional 30 g of insoluble dietary fiber on 2 separate visits. Blood samples were collected over 5 hours, and mononuclear cells (MNCs) were isolated. Results: Fiber addition to the HFHC meal significantly lowered glucose excursion in the first 90 minutes and increased insulin and C-peptide secretion throughout the 5-hour follow-up period compared with the meal alone. The HFHC meal induced increases in lipopolysaccharide (LPS) concentrations, MNC reactive oxygen species generation, and the expression of interleukin (IL)-1ß, tumor necrosis factor α (TNF-α), Toll-like receptor (TLR)-4, and CD14. The addition of fiber prevented an increase in LPS and significantly reduced the increases in ROS generation and the expression of IL-1ß, TNF-α, TLR-4, and CD14. In addition, the meal increased Suppressor of cytokine signaling (SOCS)-3 and protein tyrosine phosphatase 1B (PTP-1B) messenger RNA and protein levels, which were inhibited when fiber was added. Conclusions: The addition of fiber to a proinflammatory HFHC meal had beneficial anti-inflammatory and metabolic effects. Thus, the fiber content of the American Heart Association meal may contribute to its noninflammatory nature. If these actions of dietary fiber are sustained following long-term intake, they may contribute to fiber's known benefits in the prevention of insulin resistance, type 2 diabetes, and atherosclerosis.

Ezetimibe and simvastatin combination inhibits and reverses the pro-inflammatory and pro-atherogenic effects of cream in obese patients.

BACKGROUND AND AIMS: Inflammation and postprandial lipemia are associated with increased cardiovascular disease. We investigated whether ezetimibe and simvastatin combination, a lipid lowering combination of simvastatin and ezetimibe, exerts an anti-inflammatory effect in the fasting state and after dairy cream intake. METHODS: Twenty obese patients were randomized to either ezetimibe and simvastatin combination or placebo treatment for 6 weeks. All patients were asked to ingest 33 ml of dairy cream (300 Calories) at the beginning and at the end of intervention. Fasting and post-cream blood samples were obtained. RESULTS: At 0 week, ingestion of cream induced significant increases in MNC expression of IL-1ß (105 ± 18%), TNFα (97 ± 12%), CD68 (48 ± 8%), CD16 (141 ± 39%), MMP-9 (122 ± 31%), PECAM (66 ± 10%), TLR-4 (84 ± 11%) and TLR-2 (67 ± 9%) and in endotoxin (LPS) concentrations (49 ± 7%) (p < 0.05). Ezetimibe and simvastatin combination treatment lowered fasting total cholesterol, LDLc and Lp(a) concentrations and Apo B/A1 ratio and suppressed the MNC expression of IL-1ß and CD68 (by 21 ± 7 and 24 ± 10, p < 0.05) and the concentrations of LPS, CRP, FFA and IL-18 by 24 ± 7%, 32 ± 11%, 19 ± 8% 15 ± 4%, respectively, (p < 0.05). Cream-induced increases in the expression of IL-1ß, CD68, CD16, MMP-9, TNFα and PECAM were reduced in the ezetimibe and simvastatin combination group by 74 ± 15%, 68 ± 13%, 57 ± 13%, 64 ± 16%, 67 ± 14% and 45 ± 9%, respectively, while those of LPS and MMP-9 concentrations were reduced by 53 ± 9% and 38 ± 8%, respectively, compared to the increases at week 0 (p < 0.05). There was a suppression of TLR-2 and TLR-4 expression by 21 ± 8% and 18 ± 7%, respectively, compared to 0-h baseline, after cream intake following ezetimibe and simvastatin combination treatment. CONCLUSIONS: Ezetimibe and simvastatin combination exerts a profound anti-inflammatory effect both in the fasting state and acutely after the ingestion of saturated fat.

Insulin Resistance and Inflammation in Hypogonadotropic Hypogonadism and Their Reduction After Testosterone Replacement in Men With Type 2 Diabetes.

OBJECTIVE: One-third of men with type 2 diabetes have hypogonadotropic hypogonadism (HH). We conducted a randomized placebo-controlled trial to evaluate the effect of testosterone replacement on insulin resistance in men with type 2 diabetes and HH. RESEARCH DESIGN AND METHODS: A total of 94 men with type 2 diabetes were recruited into the study; 50 men were eugonadal, while 44 men had HH. Insulin sensitivity was calculated from the glucose infusion rate (GIR) during hyperinsulinemic-euglycemic clamp. Lean body mass and fat mass were measured by DEXA and MRI. Subcutaneous fat samples were taken to assess insulin signaling genes. Men with HH were randomized to receive intramuscular testosterone (250 mg) or placebo (1 mL saline) every 2 weeks for 24 weeks. RESULTS: Men with HH had higher subcutaneous and visceral fat mass than eugonadal men. GIR was 36% lower in men with HH. GIR increased by 32% after 24 weeks of testosterone therapy but did not change after placebo (P = 0.03 for comparison). There was a decrease in subcutaneous fat mass (-3.3 kg) and increase in lean mass (3.4 kg) after testosterone treatment (P < 0.01) compared with placebo. Visceral and hepatic fat did not change. The expression of insulin signaling genes (IR-ß, IRS-1, AKT-2, and GLUT4) in adipose tissue was significantly lower in men with HH and was upregulated after testosterone treatment. Testosterone treatment also caused a significant fall in circulating concentrations of free fatty acids, C-reactive protein, interleukin-1ß, tumor necrosis factor-α, and leptin (P < 0.05 for all). CONCLUSIONS: Testosterone treatment in men with type 2 diabetes and HH increases insulin sensitivity, increases lean mass, and decreases subcutaneous fat.

Suppressive effect of insulin on the gene expression and plasma concentrations of mediators of asthmatic inflammation.

BACKGROUND AND HYPOTHESIS: Following our recent demonstration that the chronic inflammatory and insulin resistant state of obesity is associated with an increase in the expression of mediators known to contribute to the pathogenesis of asthma and that weight loss after gastric bypass surgery results in the reduction of these genes, we have now hypothesized that insulin suppresses the cellular expression and plasma concentrations of these mediators. METHODS: The expression of IL-4, LIGHT, LTBR, ADAM-33, and TSLP in MNC and plasma concentrations of LIGHT, TGF-ß1, MMP-9, MCP-1, TSLP, and NOM in obese patients with T2DM were measured before, during, and after the infusion of a low dose (2 U/h) infusion of insulin for 4 hours. The patients were also infused with dextrose or saline for 4 hours on two separate visits and served as controls. Results. Following insulin infusion, the mRNA expression of IL-4, ADAM-33, LIGHT, and LTBR mRNA expression fell significantly (P < 0.05 for all). There was also a concomitant reduction in plasma NOM, LIGHT, TGF-ß1, MCP-1, and MMP-9 concentrations. CONCLUSIONS: Insulin suppresses the expression of these genes and mediators related to asthma and may, therefore, have a potential role in the treatment of asthma.