Type 2 diabetes mellitus pharmacological remission with dapagliflozin plus oral semaglutide.

Dapagliflozin, a sodium-glucose co-transporter-2 inhibitor and semaglutide, a glucagon-like peptide 1 receptor agonist, have both demonstrated efficacy in glycemic control, reducing blood pressure, body weight, risk of renal and heart failure in type 2 diabetes mellitus. In this observational, real-world, study we aimed to investigate the efficacy of the combination therapy with those two agents over glycemic control. We thus obtained the data of 1335 patients with type 2 diabetes followed by 11 Diabetes centers in Lombardia, Italy. A group of 443 patients was treated with dapagliflozin alone, the other group of 892 patients was treated with the combination therapy of dapagliflozin plus oral semaglutide. We analyzed changes in glycated hemoglobin from baseline to 6 months of follow-up, as well as changes in fasting glycemia, body weight, body mass index, systolic and diastolic pressure, heart rate, creatinine, estimated glomerular filtration rate and albuminuria. Both groups of patients showed an improvement of glycometabolic control after 6 months of treatment; indeed, the treatment with dapagliflozin plus oral semaglutide showed a reduction of glycated hemoglobin of 1.2% as compared to the 0.5% reduction observed in the dapagliflozin alone group. Significant changes were observed in body mass index, fasting plasmatic glucose, blood pressure, total cholesterol, LDL and albumin to creatinine ratio, with a high rate (55%) of near-normalization of glycated hemoglobin. Our real world data confirmed the potential of the oral combination therapy dapagliflozin with semaglutide in inducing pharmacological remission of type 2 diabetes mellitus.

Daytime hypoglycemic episodes during the use of an advanced hybrid closed loop system.

AIMS: The use of advanced hybrid closed loop systems is spreading due to the beneficial effects on glycometabolic control obtained in patients with type 1 diabetes. However, hypoglycemic episodes can be sometimes a matter of concern. We aim to compare the hypoglycemic risk of an advanced hybrid closed loop system and a predictive low glucose suspend sensor augmented pump. METHODS: In this retrospective three months observational study, we included 30 patients using Medtronic Minimed™ 780G advanced hybrid closed loop system and 30 patients using a Medtronic Minimed™ predictive low glucose suspend sensor augmented pump. RESULTS: The advanced hybrid closed loop system reduced the time spent above 180 mg/dL threshold and increased the time in range as compared to the predictive low glucose suspend. No severe hypoglycemia occurred in both groups and no differences were observed in the percentage of time spent below 70 mg/dl and 54 mg/dl glucose threshold. Nevertheless, more hypoglycemic episodes were recorded during daytime, but not in nighttime, with the use of the advanced hybrid closed loop system. CONCLUSIONS: Our results confirmed the general improvement of glycemic outcomes obtained with the advanced hybrid closed loop system; however more hypoglycemic episodes during daytime were evident.

AWARE A novel web application to rapidly assess cardiovascular risk in type 2 diabetes mellitus.

AIM: To describe the development of the AWARE App, a novel web application for the rapid assessment of cardiovascular risk in Type 2 Diabetes Mellitus (T2DM) patients. We also tested the feasibility of using this App in clinical practice. METHODS: Based on 2019 European Society of Cardiology/European Association for the Study of Diabetes criteria for cardiovascular risk stratification in T2DM, the AWARE App classifies patients into very high (VHCVR), high (HCVR) and moderate (MCVR) cardiovascular risk categories. In this retrospective clinical study, we employed the App to assess the cardiovascular risk of T2DM patients, while also collecting data about current glycaemic control and pharmacological treatment. RESULTS: 2243 T2DM consecutive patients were evaluated. 72.2% of the patients were VHCVR, 8.9% were HCVR, 0.8% were MCVR while 18.2% did not fit into any of the risk categories and were classified as "moderate-to-high" (MHCVR). Compared with the other groups, patients with VHCVD were more frequently ≥ 65 years old (68.9%), with a longer disease duration (≥ 10 years [56.8%]), a history of cardiovascular disease (41.4%), organ damage (35.5%) and a higher numbers of cardiovascular risk factors. Patients with MHCVD generally had disease duration < 10 years (96%), younger age (50-60 years [55%]), no history of cardiovascular disease, no organ damage, and 1-2 cardiovascular risk factors (89%). Novel drugs such as Glucagon Like Peptyde 1 Receptor Agonists or Sodium-Glucose Linked Transporter 2 inhibitors were prescribed only to 26.3% of the patients with VHCVR and to 24.7% of those with HCVR. Glycaemic control was unsatisfactory in this patients population (HbA1c 7.5 ± 3.4% [58.7 ± 13.4 mmol/mol]). CONCLUSIONS: The AWARE App proved to be a practical tool for cardiovascular risk stratification of T2DM patients in real-world clinical practice.

SGLT2-inhibitors are effective and safe in the elderly: The SOLD study.

BACKGROUND AND AIMS: Sodium-glucose co-transporter-2 inhibitors (SGLT2i) may have important benefits for the elderly with type 2 diabetes (T2D), however some safety concerns still limit their use in patients over 70 years of age. The SOLD study (SGLT2i in Older Diabetic patients) is a multicenter study, aimed to evaluate the effectiveness and safety of SGLT2i in the older diabetic patients in a real-life setting. MATERIALS AND METHODS: We analyzed a population of 739 adults (mean age 75.4 ± 3.9 years, M/F 420/319) with T2D, which started a SGLT2i-based treatment after the age of 70, with at least one year of follow-up. Data were collected at baseline, at 6 and 12 months of follow-up. RESULTS: SGLT2i (37.5% Empagliflozin, 35.7% Dapagliflozin, 26.1% Canagliflozin, 0.7% Ertugliflozin) were an add-on therapy to Metformin in 88.6%, to basal insulin in 36.1% and to other antidiabetic drugs in 29.6% of cases. 565 subjects completed the follow up, while 174 (23.5%) discontinued treatment due to adverse events which were SGLT2i related. A statistically significant reduction of glycated hemoglobin (baseline vs 12 months: 7.8 ± 1.1 vs 7.1 ± 0.8%, p < 0.001) and body mass index values (baseline vs 12 months: 29.2 ± 4.7 vs 28.1 ± 4.5 kg/m2, p < 0.001) were evident during follow-up. Overall, estimated glomerular filtration rate remained stable over time, with significant reduction of urinary albumin excretion. In the subgroup of patients which were ≥ 80 years, a significant improvement in glycated hemoglobin values without renal function alterations was evident. Overall discontinuation rate during the follow-up period was different across age groups, being urinary tract infections and worsening of renal function the most common cause. CONCLUSION: SGLT2i are well-tolerated and safe in the elderly and appear as an effective therapeutic option, though some caution is also suggested, especially in more fragile subjects.

Obesity and COVID-19: the ominous duet affecting the renin-angiotensin system.

The world population is facing a health challenge never seen since the Spanish influenza of one hundred years ago. During the last months, the scientific community has been debating on the potential harmful effect of angiotensin-converting-enzyme inhibitors (ACEi) or angiotensin II receptor type 1 receptor blockers (AT1-receptor blockers, ARBs) during the COVID-19 pandemic. That is because the S spike protein of SARS-CoV viruses utilizes the angiotensin-converting enzyme 2 (ACE2) as a receptor to enter alveolar epithelial cells. Obesity, often associated to type 2 Diabetes, was shown to worsen the prognosis of SARS-CoV-2 infection. Herein we discuss the complex interaction between the renin-angiotensin-aldosterone system (RAAS), its receptors, and the interaction with the Kallikrein-Kinin-system (KKS) and the potential activation of the coagulation cascade. Alteration of the equilibrium between the RAAS system and the KKS cascade may explain the frequent thromboembolic complications of COVID-19 mainly seen in obese and diabetic-obese patients. In contrast, angiotensin (1-7) contributes to maintaining a correct balance between RAAS and KKS system. Our conclusion is that the higher mortality rate in patients with obesity is linked to the alteration of RAS and RAS-KKS interaction consequent to SARS-CoV-2-cell entrance. At present, no data support the necessity of modifying ACEi or ARBs treatment in hypertensive patients.

Use of Liraglutide in the Real World and Impact at 36 Months on Metabolic Control, Weight, Lipid Profile, Blood Pressure, Heart Rate, and Renal Function.

PURPOSE: An observational retrospective study was conducted by 2 diabetes clinics in Italy to assess patterns of use and long-term effectiveness of liraglutide on established and emerging parameters. METHODS: Data from 261 patients with type 2 diabetes who started treatment with liraglutide between 2010 and 2014 were collected. Hierarchical linear regression models were applied to assess trends over time of clinical parameters. Factors associated with higher likelihood of dropout were identified through multivariate logistic analysis. FINDINGS: Liraglutide was initiated as a switch in 42.5% of patients and as an add-on in 49.8%; in 7.7% of the patients initiation of liraglutide was associated with a reduction in the number of pharmacologic agents. A statistically significant reduction after 36 months was found for the following parameters (mean change [95% CIs]): glycosylated hemoglobin (HbA1c; -1.01% [1.34% to -0.68%]), fasting blood glucose (-27.5 [-40.6 to -14.4] mg/dL), weight (-2.9 [-4.5 to -1.3] kg), body mass index (-1.13 [-1.76 to -0.50] kg/m2), waist circumference (-1.74 [-3.85 to -0.37] cm), and LDL-C (-24.7 [-36.67 to -12.8] mg/dL). Improvements in systolic (-3.5 mm Hg) and diastolic (-2.3 mm Hg) blood pressures were observed at 24 months. Albuminuria was reduced by -16.6 mg/L during 36 months, although statistical significance was not reached. Glomerular filtration rate and heart rate were unchanged. Reductions in HbA1c between -0.6% and -1.3% were obtained in specific subgroups. Treatment was effective also in patients with >20 years of diabetes duration, although the likelihood of dropout was 6% higher for each additional year of disease duration (RR = 1.06; 95% CI, 1.01-1.12). The likelihood of dropout was almost four times higher for subjects treated with insulin (RR = 3.82; 95% CI, 1.22-11.96) and more than twice for those treated with sulfonylureas (RR = 2.39; 95% CI, 1.16-4.94) compared with patients not treated with these agents. IMPLICATIONS: Liraglutide used in routine clinical conditions maintains its effectiveness on metabolic control and weight after 3 years. Improvements in terms of metabolic control were found when liraglutide was used as both switch and add-on treatment. In addition, improvements were sustained when liraglutide replaced sulfonylureas or insulin. Diabetes duration had no impact on drug efficacy. Long-term benefits relative to blood pressure and LDL-C were also found, which could not be entirely explained by antihypertensive/lipid-lowering treatment intensification. No major effect on renal parameters was documented. Diabetes duration and some concomitant treatments were associated with a higher likelihood of liraglutide discontinuation. These data can contribute to improve appropriateness and cost-effectiveness profile of liraglutide.

The protective effect of the Mediterranean diet on endothelial resistance to GLP-1 in type 2 diabetes: a preliminary report.

BACKGROUND: In type 2 diabetes, acute hyperglycemia worsens endothelial function and inflammation,while resistance to GLP-1 action occurs. All these phenomena seem to be related to the generation of oxidative stress. A Mediterranean diet, supplemented with olive oil, increases plasma antioxidant capacity, suggesting that its implementation can have a favorable effect on the aforementioned phenomena. In the present study, we test the hypothesis that a Mediterranean diet using olive oil can counteract the effects of acute hyperglycemia and can improve the resistance of the endothelium to GLP-1 action. METHODS: Two groups of type 2 diabetic patients, each consisting of twelve subjects, participated in a randomized trial for three months, following a Mediterranean diet using olive oil or a control low-fat diet. Plasma antioxidant capacity, endothelial function, nitrotyrosine, 8-iso-PGF2a, IL-6 and ICAM-1 levels were evaluated at baseline and at the end of the study. The effect of GLP-1 during a hyperglycemic clamp, was also studied at baseline and at the end of the study. RESULTS: Compared to the control diet, the Mediterranean diet increased plasma antioxidant capacity and improved basal endothelial function, nitrotyrosine, 8-iso-PGF2a, IL-6 and ICAM-1 levels. The Mediterranean diet also reduced the negative effects of acute hyperglycemia, induced by a hyperglycemic clamp, on endothelial function, nitrotyrosine, 8-iso-PGF2a, IL-6 and ICAM-1 levels. Furthermore, the Mediterranean diet improved the protective action of GLP-1 on endothelial function, nitrotyrosine, 8-iso-PGF2a, IL-6 and ICAM-1 levels, also increasing GLP-1-induced insulin secretion. CONCLUSIONS: These data suggest that the Mediterranean diet, using olive oil, prevents the acute hyperglycemia effect on endothelial function, inflammation and oxidative stress, and improves the action of GLP-1, which may have a favorable effect on the management of type 2 diabetes, particularly for the prevention of cardiovascular disease.

Simultaneous GLP-1 and insulin administration acutely enhances their vasodilatory, antiinflammatory, and antioxidant action in type 2 diabetes.

OBJECTIVE: To test the hypothesis that the simultaneous administration of GLP-1 and insulin may increase their vasodilatory, antiinflammatory, and antioxidant action in type 2 diabetes. RESEARCH DESIGN AND METHODS: In two groups of persons with type 2 diabetes, two sets of experiments were performed. The first group had two normoglycemic-normoinsulinemic clamps with or without GLP-1 and two normoglycemic-hyperinsulinemic clamps with or without GLP-1. The second group had two hyperglycemic-normoinsulinemic clamps and two hyperglycemic-hyperinsulinemic clamps with or without GLP-1. RESULTS: During the normoglycemic-hyperinsulinemic clamp, flow-mediated dilatation (FMD) increased, while soluble intercellular adhesion molecule (sICAM-1), plasma 8-iso-prostaglandin F2α (8-iso-PGF2α), nitrotyrosine, and interleukin (IL)-6 decreased compared with normoglycemic-normoinsulinemic clamp. Similar results were obtained with the infusion of GLP-1 during the normoglycemic-normoinsulinemic clamp. The combination of hyperinsulinemia and GLP-1 in normoglycemia was accompanied by a further FMD increase and sICAM-1, 8-iso-PGF2α, nitrotyrosine, and IL-6 decrease. During the hyperglycemic-normoinsulinemic clamp, FMD significantly decreased, while sICAM-1, 8-iso-PGF2α, nitrotyrosine, and IL-6 significantly increased. When hyperglycemia was accompanied by hyperinsulinemia or by the simultaneous infusion of GLP-1, these phenomena were attenuated. The simultaneous presence of hyperinsulinemia and GLP-1 had an increased beneficial effect. CONCLUSIONS: Our results show that the combination of insulin and GLP-1 is more effective than insulin or GLP-1 alone in improving endothelial dysfunction, inflammation, and oxidative stress in type 2 diabetes.

Peripheral venous congestion causes inflammation, neurohormonal, and endothelial cell activation.

AIMS: Volume overload and venous congestion are typically viewed as a consequence of advanced and of acute heart failure (HF) and renal failure (RF) although it is possible that hypervolaemia itself might be a critical intermediate in the pathophysiology of these diseases. This study aimed at elucidating whether peripheral venous congestion is sufficient to promote changes in inflammatory, neurohormonal, and endothelial phenotype similar to those observed in HF and RF. METHODS: To experimentally model peripheral venous congestion, we developed a new method (so-called venous stress test) and applied the methodology on 24 healthy subjects (14 men, age 35 ± 2 years). Venous arm pressure was increased to ∼30 mmHg above the baseline level by inflating a tourniquet cuff around the dominant arm (test arm). Blood and endothelial cells (ECs) were sampled from test and control arm (lacking an inflated cuff) before and after 75 min of venous congestion, using angiocatheters and endovascular wires. Magnetic beads coated with EC-specific antibodies were used for EC separation; amplified mRNA was analysed by Affymetrix HG-U133 Plus 2.0 Microarray. RESULTS: Plasma interleukin-6 (IL-6), endothelin-1 (ET-1), angiotensin II (AII), vascular cell adhesion molecule-1 (VCAM-1), and chemokine (C-X-C motif) ligand 2 (CXCL2) were significantly increased in the congested arm. A total of 3437 mRNA probe sets were differentially expressed (P < 0.05) in venous ECs before vs. after testing, including ET-1, VCAM-1, and CXCL2. CONCLUSION: Peripheral venous congestion causes release of inflammatory mediators, neurohormones, and activation of ECs. Overall, venous congestion mimicked, notable aspects of the phenotype typical of advanced and of acute HF and RF.

Vitamin C further improves the protective effect of glucagon-like peptide-1 on acute hypoglycemia-induced oxidative stress, inflammation, and endothelial dysfunction in type 1 diabetes.

OBJECTIVE: To test the hypothesis that acute hypoglycemia induces endothelial dysfunction and inflammation through the generation of an oxidative stress. Moreover, to test if the antioxidant vitamin C can further improve the protective effects of glucagon-like peptide 1 (GLP-1) on endothelial dysfunction and inflammation during hypoglycemia in type 1 diabetes. RESEARCH DESIGN AND METHODS: A total of 20 type 1 diabetic patients underwent four experiments: a period of 2 h of acute hypoglycemia with or without infusion of GLP-1 or vitamin C or both. At baseline, after 1 and 2 h, glycemia, plasma nitrotyrosine, plasma 8-iso prostaglandin F2a (PGF2a), soluble intracellular adhesion molecule-1a (sICAM-1a), interleukin-6 (IL-6), and flow-mediated vasodilation were measured. At 2 h of hypoglycemia, flow-mediated vasodilation significantly decreased, while sICAM-1, 8-iso-PGF2a, nitrotyrosine, and IL-6 significantly increased. The simultaneous infusion of GLP-1 or vitamin C significantly attenuated all of these phenomena. Vitamin C was more effective. When GLP-1 and vitamin C were infused simultaneously, the deleterious effect of hypoglycemia was almost completely counterbalanced. RESULTS: At 2 h of hypoglycemia, flow-mediated vasodilation significantly decreased, while sICAM-1, 8-iso-PGF2a, nitrotyrosine, and IL-6 significantly increased. The simultaneous infusion of GLP-1 or vitamin C significantly attenuated all of these phenomena. Vitamin C was more effective. When GLP-1 and vitamin C were infused simultaneously, the deleterious effect of hypoglycemia was almost completely counterbalanced. CONCLUSIONS: This study shows that vitamin C infusion, during induced acute hypoglycemia, reduces the generation of oxidative stress and inflammation, improving endothelial dysfunction, in type 1 diabetes. Furthermore, the data support a protective effect of GLP-1 during acute hypoglycemia, but also suggest the presence of an endothelial resistance to the action of GLP-1, reasonably mediated by oxidative stress.

Vitamin C further improves the protective effect of GLP-1 on the ischemia-reperfusion-like effect induced by hyperglycemia post-hypoglycemia in type 1 diabetes.

BACKGROUND: It has been reported that hyperglycemia following hypoglycemia produces an ischemia-reperfusion-like effect in type 1 diabetes. In this study the possibility that GLP-1 has a protective effect on this phenomenon has been tested. METHODS: 15 type 1 diabetic patients underwent to five experiments: a period of two hours of hypoglycemia followed by two hours of normo-glycemia or hyperglycemia with the concomitant infusion of GLP-1 or vitamin C or both. At baseline, after 2 and 4 hours, glycemia, plasma nitrotyrosine, plasma 8-iso prostaglandin F2alpha, sCAM-1a, IL-6 and flow mediated vasodilation were measured. RESULTS: After 2 h of hypoglycemia, flow mediated vasodilation significantly decreased, while sICAM-1, 8-iso-PGF2a, nitrotyrosine and IL-6 significantly increased. While recovering with normoglycemia was accompanied by a significant improvement of endothelial dysfunction, oxidative stress and inflammation, a period of hyperglycemia after hypoglycemia worsens all these parameters. These effects were counterbalanced by GLP-1 and better by vitamin C, while the simultaneous infusion of both almost completely abolished the effect of hyperglycemia post hypoglycemia. CONCLUSIONS: This study shows that GLP-1 infusion, during induced hyperglycemia post hypoglycemia, reduces the generation of oxidative stress and inflammation, improving the endothelial dysfunction, in type 1 diabetes. Furthermore, the data support that vitamin C and GLP-1 may have an additive protective effect in such condition.

Soluble forms of RAGE in human diseases: clinical and therapeutical implications.

The ligand - receptor for advanced glycation end-products (RAGE) axis has emerged as a novel pathway involved in a wide spectrum of diseases, including diabetes mellitus, atherothrombosis, chronic renal failure, rheumatoid arthritis, neurodegeneration, cancer and aging. Circulating soluble forms of RAGE (sRAGE), arising from receptor ectodomain shedding and splice variant [endogenous secretory (es) RAGE] secretion, may counteract RAGE-mediated pathogenesis, by acting as a decoy. Several studies suggest that decreased levels of sRAGE and/or esRAGE may be useful as a biomarker of ligand-RAGE pathway hyperactivity and inadequate endogenous protective response, thus providing a powerful complement to cardiovascular risk stratification and an interesting target of therapeutic interventions. This review will focus on the pathophysiological determinants of soluble forms of RAGE in different clinical settings, with particular reference to the mechanisms involved in their generation and clearance, the association with cardiovascular risk factors, the interplay with low-grade inflammation, oxidative stress and endothelial dysfunction, and the possible pharmacological modulation of their plasma levels.

Inflammatory stress in primary venous and aortic endothelial cells of type 1 diabetic mice.

OBJECTIVE: The progression of diabetes is associated with profound endothelial dysfunction. We tested the hypothesis that cellular stress would be detectable in ECs retrieved from arterial and venous vessels of diabetic mice. METHOD: We describe a method for direct isolation of well-characterised aortic and venous ECs from mice in which cells are not subjected to propagation in culture. RESULTS: Gene expression profiling, confirmed by real-time PCR, revealed a progressive increase in markers of injury within two main gene families, EC activation and EC apoptosis, in aortic and venous ECs recovered from diabetic versus non-diabetic mice. In short-term diabetes, Il1b mRNA transcripts were higher in aortic and venous ECs of diabetic mice versus controls. In long-term diabetes, casp-1 mRNA transcripts were higher in aortic and venous ECs of diabetic mice versus controls. CONCLUSION: These data suggest that diabetes imparts diffuse endothelial perturbation in the arterial and venous endothelium.

RAGE and modulation of ischemic injury in the diabetic myocardium.

OBJECTIVE: Subjects with diabetes experience an increased risk of myocardial infarction and cardiac failure compared with nondiabetic age-matched individuals. The receptor for advanced glycation end products (RAGE) is upregulated in diabetic tissues. In this study, we tested the hypothesis that RAGE affected ischemia/reperfusion (I/R) injury in the diabetic myocardium. In diabetic rat hearts, expression of RAGE and its ligands was enhanced and localized particularly to both endothelial cells and mononuclear phagocytes. RESEARCH DESIGN AND METHODS: To specifically dissect the impact of RAGE, homozygous RAGE-null mice and transgenic (Tg) mice expressing cytoplasmic domain-deleted RAGE (DN RAGE), in which RAGE-dependent signal transduction was deficient in endothelial cells or mononuclear phagocytes, were rendered diabetic with streptozotocin. Isolated perfused hearts were subjected to I/R. RESULTS: Diabetic RAGE-null mice were significantly protected from the adverse impact of I/R injury in the heart, as indicated by decreased release of LDH and lower glycoxidation products carboxymethyl-lysine (CML) and pentosidine, improved functional recovery, and increased ATP. In diabetic Tg mice expressing DN RAGE in endothelial cells or mononuclear phagocytes, markers of ischemic injury and CML were significantly reduced, and levels of ATP were increased in heart tissue compared with littermate diabetic controls. Furthermore, key markers of apoptosis, caspase-3 activity and cytochrome c release, were reduced in the hearts of diabetic RAGE-modified mice compared with wild-type diabetic littermates in I/R. CONCLUSIONS: These findings demonstrate novel and key roles for RAGE in I/R injury in the diabetic heart.

Decreased plasma soluble RAGE in patients with hypercholesterolemia: effects of statins.

The receptor for advanced glycation endproducts (RAGE) is overexpressed at sites of vascular pathology. A soluble RAGE isoform (sRAGE) neutralizes the ligand-mediated damage by acting as a decoy. We hypothesized that in hypercholesterolemia up-regulation of the ligand-RAGE axis may bridge impairment of nitric oxide biosynthesis with oxidative stress. We measured in 60 hypercholesterolemic patients and 20 controls plasma total sRAGE levels, urinary 8-iso-prostaglandin (PG) F(2alpha) excretion, and plasma levels of asymmetric dimethylarginine (ADMA). The effects of two structurally different statins (pravastatin and atorvastatin) on these parameters were analyzed in 20 hypercholesterolemic subjects free of vascular disease. Plasma sRAGE was significantly lower, ADMA and urinary 8-iso-PGF(2alpha) were higher, in hypercholesterolemic versus normocholesterolemic patients. Patients on statin treatment with previous myocardial infarction had lower 8-iso-PGF(2alpha), higher sRAGE, and unchanged ADMA levels compared to subjects free of vascular disease. On multivariate regression analysis only 8-iso-PGF(2alpha) and ADMA predicted sRAGE levels. An 8-week treatment with either statin was associated with a significant reduction in urinary 8-iso-PGF(2alpha), whereas only atorvastatin raised sRAGE levels near to normal values, with no change in ADMA levels. sRAGE might serve as an endogenous protecting factor for accelerated atherosclerosis mediated by oxidative stress and endothelial dysfunction in hypercholesterolemia.

Soluble RAGE in type 2 diabetes: association with oxidative stress.

Advanced glycation end products (AGEs) contribute to diabetic vascular complications by engaging the AGE receptor (RAGE). A soluble RAGE form (sRAGE) acts as a decoy domain receptor, thus decreasing AGE cellular binding. A cross-sectional comparison of sRAGE, asymmetric dimethylarginine (ADMA) plasma levels (index of endothelial dysfunction), and urinary 8-iso-prostaglandin (PG)F(2alpha) (marker of oxidative stress) was performed between 86 diabetic patients and 43 controls. Plasma sRAGE levels were significantly lower and ADMA levels were significantly higher in diabetic patients as compared to controls (P<0.0001). HbA1c and urinary 8-iso-PGF(2alpha) were correlated inversely with sRAGE and directly with ADMA. On multivariate analysis HbA1c was independently related to sRAGE levels in diabetic patients. Twenty-four of 86 patients with newly diagnosed diabetes and 12 patients in poor metabolic control were reevaluated after treatment with a hypoglycemic agent or insulin, respectively. Improvement in metabolic control by oral agents or insulin resulted in a significant increase in sRAGE and decrease in ADMA levels (P<0.0001). Thus, poor glycemic control reduces sRAGE levels, in association with enhanced oxidative stress and endothelial dysfunction in diabetes. These abnormalities are susceptible to modulation by improvement in metabolic control.

Receptor for advanced-glycation end products: key modulator of myocardial ischemic injury.

BACKGROUND: The beneficial effects of reperfusion therapies have been limited by the amount of ischemic damage that occurs before reperfusion. To enable development of interventions to reduce cell injury, our research has focused on understanding mechanisms involved in cardiac cell death after ischemia/reperfusion (I/R) injury. In this context, our laboratory has been investigating the role of the receptor for advanced-glycation end products (RAGE) in myocardial I/R injury. METHODS AND RESULTS: In this study we tested the hypothesis that RAGE is a key modulator of I/R injury in the myocardium. In ischemic rat hearts, expression of RAGE and its ligands was significantly enhanced. Pretreatment of rats with sRAGE, a decoy soluble part of RAGE receptor, reduced ischemic injury and improved functional recovery of myocardium. To specifically dissect the impact of RAGE, hearts from homozygous RAGE-null mice were isolated, perfused, and subjected to I/R. RAGE-null mice were strikingly protected from the adverse impact of I/R injury in the heart, as indicated by decreased release of LDH, improved functional recovery, and increased adenosine triphosphate (ATP). In rats and mice, activation of the RAGE axis was associated with increases in inducible nitric oxide synthase expression and levels of nitric oxide, cyclic guanosine monophosphate (cGMP), and nitrotyrosine. CONCLUSIONS: These findings demonstrate novel and key roles for RAGE in I/R injury in the heart. The findings also demonstrate that the interaction of RAGE with advanced-glycation end products affects myocardial energy metabolism and function during I/R.

RAGE modulates vascular inflammation and atherosclerosis in a murine model of type 2 diabetes.

Previous studies demonstrated that induction of diabetes with streptozotocin (stz) accelerated atherosclerosis in hyperlipidemic apo E null (-/-) mice. Blockade of the Receptor for Advanced Glycation Endproducts (RAGE) in those animals suppressed acceleration of atherosclerotic lesion area, in a manner independent of changes in levels of glucose, insulin or lipids. In the present studies, we extended these concepts to a murine model of type 2 diabetes, and bred apo E -/- mice into the db/db background. Db/db mice are a model of obesity and insulin resistance-mediated hyperglycemia. Compared to apo E -/- m/db (non-diabetic) mice, apo E -/- db/db (diabetic) mice displayed accelerated atherosclerosis at the aortic sinus. Consistent with an important role for RAGE in this process, administration of soluble (s) RAGE, the extracellular ligand-binding domain of RAGE, resulted in significantly reduced atherosclerotic lesion area in a glycemia- and lipid-independent manner. In parallel, apo E -/- db/db mice displayed RAGE-dependent enhanced expression of Vascular Cell Adhesion Molecule-1, tissue factor and matrix metalloproteinase (MMP)-9 antigen/activity in aortae compared to non-diabetic animals. In addition, consistent with the premise that upregulation of RAGE ligands and RAGE occurs even in the non-diabetic, hyperlipidemic state, albeit to lesser degrees than in diabetes, administration of sRAGE to apo E -/- m/db mice resulted in decreased atherosclerotic lesion area at the aortic sinus. Taken together, these findings establish a new murine model for the study of atherosclerosis in type 2 diabetes and highlight important roles for RAGE in proatherogenic mechanisms in hyperglycemia triggered by insulin resistance.

Diabetic vascular disease: it's all the RAGE.

The major consequence of long-term diabetes is the increased incidence of disease of the vasculature. Of the underlying mechanisms leading to disease, the accumulation of advanced glycation end products (AGEs), resulting from the associated hyperglycemia, is the most convincing. Interaction of AGEs with their receptor, RAGE, activates numerous signaling pathways leading to activation of proinflammatory and procoagulatory genes. Studies in rodent models of macro- and microvascular disease have demonstrated that blockade of RAGE can prevent development of disease. These observations highlight RAGE as a therapeutic target for treatment of diabetic vascular disease.

Aldose reductase and AGE-RAGE pathways: key players in myocardial ischemic injury.

Cardiovascular disease represents the major cause of morbidity and mortality in patients with diabetes mellitus. The impact of cardiac disease includes increased sensitivity of diabetic myocardium to ischemic episodes and diabetic cardiomyopathy, manifested as a subnormal functional response of the diabetic heart independent of coronary artery disease. In this context, we were to our knowledge the first to demonstrate that diabetes increases glucose flux via the first and key enzyme, aldose reductase, of the polyol pathway, resulting in impaired glycolysis under normoxic and ischemic conditions in diabetic myocardium. Our laboratory has been investigating the role of the polyol pathway in mediating myocardial ischemic injury in diabetics. Furthermore, the influence of the aldose reductase pathway in facilitating generation of key potent glycating compounds has led us to investigate the impact of advanced glycation end products (AGEs) in myocardial ischemic injury in diabetics. The potent impact of increased flux via the aldose reductase pathway and the increased AGE interactions with its receptor (RAGE) resulting in cardiac dysfunction will be discussed in this chapter.