GLP-1-dependent and independent effects and molecular mechanisms of a dipeptidyl peptidase 4 inhibitor in vascular endothelial cells.

The potential atheroprotective effects of glucagon-like peptide-1 (GLP-1), long-acting GLP-1 analogues and inhibitors of the enzyme dipeptidyl peptidase 4 (DPP-4) are currently the subject of intense research. Recent evidence suggests the effects of DPP-IV inhibitors, may, in-part, be mediated by GLP-1 independent molecular mechanisms. In this report we demonstrate that treatment of human vascular endothelial cells with the DPP-IV inhibitor sitagliptin inhibited tumour necrosis factor alpha (TNFα) induction of plasminogen activator inhibitor type-1 (PAI-1), intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) mRNA and protein expression and that this effect was observed to be both GLP-1-dependent and independent. Importantly we identify a molecular mechanism involving sitagliptin-mediated attenuation of TNFα-mediated induction of NFκB and orphan nuclear receptor NUR77 mRNA expression, also able to be reproduced, in part, independent of GLP-1. Taken together these observations may serve to provide a molecular explanation, involving transcriptional regulation of gene expression, for recent in vivo studies suggesting DPP-IV inhibitors may have novel, GLP-1 independent, effects in acting to attenuate endothelial cell dysfunction and atherogenesis.

Dapagliflozin attenuates human vascular endothelial cell activation and induces vasorelaxation: A potential mechanism for inhibition of atherogenesis.

BACKGROUND: Sodium glucose transporter type 2 inhibitors may reduce cardiovascular events in type 2 diabetes. Our study aimed to determine the effect of the sodium glucose transporter type 2 inhibitor dapagliflozin on endothelial cell activation, vasoreactivity and atherogenesis using in vitro and in vivo models and identify associated molecular mechanisms. METHODS: In vitro studies utilised human vascular endothelial cells stimulated with tumour necrosis factor α or hyperglycaemic conditions. In vivo studies were performed in C57Bl/6J mice to evaluate direct vasorelaxation responses evoked by acute dapagliflozin administration and acute vaso-protective effects of dapagliflozin on hyperglycaemia-induced endothelial dysfunction. Adult and aged Apolipoprotein E-deficient mice maintained on a high-fat diet were used to investigate endothelial-dependent vascular reactivity and atherogenesis. Dapagliflozin treatment (1.0 mg/kg/day) was administered for 4 weeks. RESULTS: In vitro studies demonstrated dapagliflozin-mediated attenuation of tumour necrosis factor α- and hyperglycaemia-induced increases in intercellular adhesion molecule-1, vascular cell adhesion molecule-1, plasminogen activator inhibitor type 1 and NFκB expression. Acute dapagliflozin administration dose-dependently induced endothelium-independent vasorelaxation. Chronic dapagliflozin treatment improved endothelial function and significantly reduced in vivo vascular adhesion molecule and phospho-IκB expression together with macrophage vessel wall infiltration. CONCLUSION: These observations identify a potential role for dapagliflozin in the attenuation of atherogenesis and identify anti-inflammatory molecular mechanisms associated with these effects.

The Efficacy of IDegLira (Insulin Degludec/Liraglutide Combination) in Adults with Type 2 Diabetes Inadequately Controlled with a GLP-1 Receptor Agonist and Oral Therapy: DUAL III Randomized Clinical Trial.

INTRODUCTION: The progressive nature of type 2 diabetes necessitates treatment intensification. This often involves intensification with oral antidiabetic drugs (OADs) initially, followed by other agents, such as glucagon-like peptide-1 receptor agonists (GLP-1RAs), with the majority of patients eventually requiring insulin therapy. Therefore, this trial aimed to investigate the efficacy of IDegLira (combination of insulin degludec and liraglutide) in controlling glycemia in adults with type 2 diabetes who were inadequately controlled on a GLP-1RA and OADs. METHODS: In this 26-week open-label phase 3b trial, patients on maximum-dose GLP-1RA therapy (liraglutide once daily or exenatide twice daily) with metformin alone or with pioglitazone and/or sulfonylurea were randomized 2:1 to IDegLira once daily (n = 292) or to unchanged GLP-1RA therapy (n = 146), continuing OADs at the pre-trial dose. RESULTS: After 26 weeks, HbA1c reductions were superior with IDegLira versus unchanged GLP-1RA; estimated treatment difference -0.94% (-10.3 mmol/mol), p < 0.001. Mean HbA1c reduced from 7.8% to 6.4% (61.5 to 46.9 mmol/mol) with IDegLira and from 7.7 to 7.4% (60.8 to 57.1 mmol/mol) with unchanged GLP-1RA. With IDegLira, 75% and 63% of patients achieved HbA1c <7% and ≤6.5%, compared with 36% and 23% on unchanged GLP-1RA, respectively. Fasting plasma glucose and 9-point self-monitored blood glucose profiles improved significantly more with IDegLira versus unchanged GLP-1RA. The mean change in weight was +2.0 kg with IDegLira, versus -0.8 kg with unchanged GLP-1RA. Rates of confirmed hypoglycemia were low, but higher with IDegLira versus unchanged GLP-1RA. The safety profile of IDegLira was consistent with previous findings; both treatments were well tolerated and the rate of nausea was low in both groups. IDegLira improved patient-reported outcomes versus unchanged GLP-1RA. CONCLUSIONS: IDegLira provided superior glycemic control versus unchanged GLP-1RA and represents an efficacious intensification approach in patients inadequately controlled on GLP-1RAs. TRIAL REGISTRATION: ClinicalTrials.gov #NCT01676116. FUNDING: Novo Nordisk.

Treatment of intractable painful diabetic neuropathy with intravenous lignocaine.

OBJECTIVE: Lignocaine is a cardiac antiarrhythmic agent occasionally used to treat neuropathic pain. This study was designed to examine the effectiveness of intravenous lignocaine in patients with intractable painful diabetic neuropathy. RESEARCH DESIGN AND METHODS: Fifteen patients with painful diabetic peripheral neuropathy, who had appeared to respond to previous lignocaine infusions, completed a double-blind, placebo-controlled crossover trial of two doses of intravenous lignocaine (5 and 7.5 mg/kg) versus saline. Infusions were administered in random order over 4 h at four weekly intervals. The effect of treatment on pain perception was assessed using the McGill Pain Questionnaire (MPQ), a daily pain diary, hours of sleep, fasting blood glucose, and use of other pain-relieving medication. RESULTS: Both doses of lignocaine significantly (P<.05 to P<.001 for the different measures) reduced the severity of pain compared with placebo. This reduction was present at both 14 and 28 days after the infusion. The qualitative nature of the pain was also significantly (P<.05 to P<.01) modified by lignocaine compared with placebo for up to 28 days. The preceding dose 4 weeks earlier significantly (P<.01 and P<.001) affected the response to the next dose. There were no significant effects of treatment on the other measures of response. There were no significant side effects of the treatment. CONCLUSIONS: This study shows that intravenous lignocaine ameliorates pain in some diabetic participants with intractable neuropathic pain who have failed to respond to or are intolerant of available conventional therapy.

Transdermal Buprenorphine Relieves Neuropathic Pain: A Randomized, Double-Blind, Parallel-Group, Placebo-Controlled Trial in Diabetic Peripheral Neuropathic Pain.

OBJECTIVE: To evaluate the efficacy and safety of transdermal buprenorphine in patients with diabetic peripheral neuropathic pain (DPNP). RESEARCH DESIGN AND METHODS: This multicenter, randomized, double-blind, placebo-controlled, parallel-group trial enrolled patients with type 1 or type 2 diabetes and stable glycemic control who had been experiencing moderate to severe DPNP for at least 6 months on maximal tolerated conventional therapy. Patients were randomly assigned to receive buprenorphine (5 µg/h) or placebo patches. The dose was titrated to effect to a maximum of 40 µg/h. Paracetamol was available as rescue analgesia. The severity of pain and other symptoms of DPNP were assessed daily in a patient diary and at clinic visits. RESULTS: One hundred eight-six patients were enrolled, with 93 randomized to either buprenorphine or placebo. A high proportion of patients did not complete the study (buprenorphine 37 of 93, placebo 24 of 93). The main reason for premature withdrawal in the buprenorphine group was adverse events commonly due to untreated nausea and/or vomiting. Among the per-protocol population, more patients in the buprenorphine group (86.3%) experienced a 30% reduction in average versus baseline pain at week 12 than those in the placebo group (56.6%, P < 0.001). A nonsignificant trend favored the buprenorphine group within the intention-to-treat analysis of the same end point (51.7% vs. 41.3%, P = 0.175). CONCLUSIONS: Transdermal buprenorphine, when tolerated, is an effective therapy for DPNP and provides another option to manage this challenging painful condition. Nausea and constipation need to be managed proactively to optimize treatment outcomes.

Molecular and cellular mechanisms of glucagon-like peptide-1 receptor agonist-mediated attenuation of cardiac fibrosis.

BACKGROUND: Glucagon-like peptide-1 receptor agonists may have a role in modulation of cardiac fibrosis. Our study aimed to determine the effect of the glucagon-like peptide-1 receptor agonist liraglutide in obesity, hypertension and age-induced murine models of cardiac fibrosis and identify associated molecular mechanisms. METHODS: C57Bl/6J mice on a high-fat diet and C57Bl/6J mice on a normal chow diet treated with angiotensin II were used to induce obesity and hypertension-mediated cardiac fibrosis, respectively. C57Bl/6J mice 20 months old were used to study age-induced cardiac fibrosis. Liraglutide treatment of 30 µg/kg/day-300 µg/kg s.c. twice daily was administered for 4 weeks. RESULTS: Liraglutide treatment attenuated obesity, hypertension and age-induced increases in interstitial cardiac fibrosis and expression of inflammatory and oxidative stress markers. CONCLUSIONS: These observations identify a potential role for liraglutide in the prevention of cardiac fibrosis and identify molecular mechanisms associated with these effects.

Prospective clinical trial of hepatitis B vaccination in adults with and without type-2 diabetes mellitus.

Objective: Patients with diabetes mellitus are at increased risk for hepatitis B virus (HBV) infection and its complications. HBV vaccination is recommended for adults with diabetes in the United States and other countries. However, few studies have assessed safety and immunogenicity of hepatitis B vaccine in such patients. We assessed the safety and immunogenicity of recombinant hepatitis B vaccine in subjects with and without diabetes mellitus. METHODS: Prospective, multi-country controlled study in 21 centers ( www.clinicaltrials.gov NCT01627340). Four hundred and sixteen participants with Type-2 diabetes and 258 controls matched for age and body mass index (BMI) (2:1 ratio) received 3-doses of HBV vaccine (Engerix-B™, GSK Vaccines, Belgium) according to a 0, 1, 6 months schedule. Antibodies were measured against HBV surface antigen and expressed as seroprotection rates (anti-HBs ≥10mIU/mL) and geometric mean concentration (GMC). RESULTS: The median age and BMI in patients with diabetes and controls (according-to-protocol cohort) were 54 y and 32.1 kg/m2, and 53 y and 30.8 kg/m2, respectively. Seroprotection rates (GMCs) one month post-dose-3 were 75.4% (147.6 mIU/mL) and 82.0% (384.2 mIU/mL) in patients with diabetes and controls, respectively. Age-stratified seroprotection rates for patients with diabetes were 88.5% (20-39 years), 81.2% (40-49 years), 83.2% (50-59 years), and 58.2% (≥60 years). The overall safety profile of hepatitis B vaccine was similar between groups. CONCLUSIONS: Hepatitis B vaccine is immunogenic in patients with diabetes and has a similar safety profile to vaccination in healthy controls. Because increasing age was generally associated with a reduction in seroprotection rates, hepatitis B vaccine should be administered as soon as possible after the diagnosis of diabetes.

Efficacy and safety of oral methazolamide in patients with type 2 diabetes: a 24-week, placebo-controlled, double-blind study.

OBJECTIVE: To evaluate the safety and efficacy of methazolamide as a potential therapy for type 2 diabetes. RESEARCH DESIGN AND METHODS: This double-blind, placebo-controlled study randomized 76 patients to oral methazolamide (40 mg b.i.d.) or placebo for 24 weeks. The primary efficacy end point for methazolamide treatment was a placebo-corrected reduction in HbA1c from baseline after 24 weeks (ΔHbA1c). RESULTS: Mean ± SD baseline HbA1c was 7.1 ± 0.7% (54 ± 5 mmol/mol; n = 37) and 7.4 ± 0.6% (57 ± 5 mmol/mol; n = 39) in the methazolamide and placebo groups, respectively. Methazolamide treatment was associated with a ΔHbA1c of -0.39% (95% CI -0.82, 0.04; P < 0.05) (-4.3 mmol/mol [-9.0, 0.4]), an increase in the proportion of patients achieving HbA1c ≤6.5% (48 mmol/mol) from 8 to 33%, a rapid reduction in alanine aminotransferase (∼10 units/L), and weight loss (2%) in metformin-cotreated patients. CONCLUSIONS: Methazolamide is the archetype for a new intervention in type 2 diabetes with clinical benefits beyond glucose control.

The GLP-1 receptor agonist liraglutide inhibits progression of vascular disease via effects on atherogenesis, plaque stability and endothelial function in an ApoE(-/-) mouse model.

Liraglutide, a once-daily glucagon-like peptide-1 receptor (GLP-1R) agonist, has been approved as a new treatment for type 2 diabetes and is the subject of a clinical trial programme to evaluate the effects on cardiovascular disease and safety. The current study aimed to determine the in vivo effect of liraglutide on progression of atherosclerotic vascular disease in the apolipoprotein E-deficient (ApoE(-/-)) mouse model and identify underlying mechanisms responsible. Liraglutide treatment inhibited progression of early onset, low-burden atherosclerotic disease in a partially GLP-1R-dependent manner in the ApoE(-/-) mouse model. In addition, liraglutide treatment inhibited progression of atherosclerotic plaque formation and enhanced plaque stability, again in a partially GLP-1R-dependent manner. No significant effect of liraglutide on progression of late onset, high-burden atherosclerotic disease was observed. In addition, no significant endothelial cell dysfunction was identified in ApoE(-/-) mice with early onset, low-burden atherosclerotic disease, although significant prevention of weight gain was observed in liraglutide-treated mice using this dietary protocol. Taken together, these results suggest a potential role for liraglutide in the prevention and stabilisation of atherosclerotic vascular disease together with possible protection against major cardiovascular events.

PPARγ-independent thiazolidinedione-mediated inhibition of NUR77 expression in vascular endothelial cells.

The thiazolidinediones (TZDs) have been reported to reduce atherogenesis in preclinical models and atherosclerosis in clinical trials in pre-diabetic and diabetic patients. Although peroxisome proliferator-activated receptor γ (PPARγ)-mediated effects on gene expression have been thought responsible for this effect, a complete understanding of the molecular mechanisms responsible remains to be fully elucidated. We have previously reported PPARγ-independent modulation of NUR77 (also known as Nr4a1), an orphan nuclear receptor deemed important in the atherogenic process, in association with TZD-mediated inhibition of tumour necrosis factor α (TNFα) induction of plasminogen activator inhibitor type 1 expression. Here, we report NUR77 mRNA expression is increased in human vascular endothelial cells (HUVEC) stimulated by TNFα and that this effect is inhibited by a TZD in a PPARγ-independent manner. TZD treatment of HUVEC also inhibited the stimulatory effects of TNFα on NUR77 promoter activity, again in a PPARγ-independent manner, confirming the transcriptional nature of this effect. TZD treatment also attenuated the binding of nuclear proteins to the nuclear factor kappa B (NF-κB)-binding site of the NUR77 promoter in HUVEC in a PPARγ-independent manner. In addition, TZD treatment also inhibited TNFα-mediated induction of NF-κB1 mRNA expression. Our results suggest a potential PPARγ-independent molecular mechanism for the anti-atherogenic effects of TZDs involving NF-κB-mediated transcriptional inhibition of cytokine-mediated induction of the orphan nuclear receptor NUR77 in HUVEC.

A GLP-1 receptor agonist liraglutide inhibits endothelial cell dysfunction and vascular adhesion molecule expression in an ApoE-/- mouse model.

The glucagon like peptide-1 receptor (GLP-1R) agonist liraglutide attenuates induction of plasminogen activator inhibitor type-1 (PAI-1) and vascular adhesion molecule (VAM) expression in human vascular endothelial cells (hVECs) in vitro and may afford protection against endothelial cell dysfunction (ECD), an early abnormality in diabetic vascular disease. Our study aimed to establish the dependence of the in vitro effects of liraglutide on the GLP-1R and characterise its in vivo effects in a mouse model of ECD. In vitro studies utilised the human vascular endothelial cell line C11-STH and enzyme-linked immunosorbent assays (ELISA) for determination of PAI-1 and VAM expression. In vivo studies of vascular reactivity and immunohistochemical analysis were performed in the ApoE(-/-) mouse model. In vitro studies demonstrated GLP-1R-dependent liraglutide-mediated inhibition of stimulated PAI-1 and VAM expression. In vivo studies demonstrated significant improvement in endothelial function in liraglutide treated mice, a GLP-1R dependent effect. Liraglutide treatment also increased endothelial nitric oxide synthase (eNOS) and reduced intercellular adhesion molecule-1 (ICAM-1) expression in aortic endothelium, an effect again dependent on the GLP-1R. Together these studies identify in vivo protection, by the GLP-1R agonist liraglutide, against ECD and provide a potential molecular mechanism responsible for these effects.

A long-acting glucagon-like peptide-1 analogue attenuates induction of plasminogen activator inhibitor type-1 and vascular adhesion molecules.

Glucagon-like peptide-1 (GLP-1) administration attenuates endothelial cell dysfunction in diabetic patients and inhibits tumour necrosis factor alpha (TNF)-mediated plasminogen activator inhibitor type-1 (PAI-1) induction in human vascular endothelial cells. The short half-life of GLP-1 mediated via degradation by the enzyme dipeptidyl peptidase 4 mandates the clinical use of long-acting GLP-1 analogues. The effects of a long-acting GLP-1 analogue on PAI-1 and vascular adhesion molecule expression in vascular endothelial cells are unknown. In this report, we demonstrate for the first time that the treatment with liraglutide, a long-acting GLP-1 analogue, inhibited TNF or hyperglycaemia-mediated induction of PAI-1, intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 mRNA and protein expression in a human vascular endothelial cell line. In addition, treatment attenuated TNF- or hyperglycaemia-mediated induction of the orphan nuclear receptor Nur77 mRNA expression. Taken together, these observations indicate that liraglutide inhibits TNF- or glucose-mediated induction of PAI-1 and vascular adhesion molecule expression, and this effect may involve the modulation of NUR77. These effects suggest that liraglutide may potentially improve the endothelial cell dysfunction associated with premature atherosclerosis identified in type 2 diabetic patients.

Glucagon-like peptide-1 attenuates tumour necrosis factor-alpha-mediated induction of plasminogen [corrected] activator inhibitor-1 expression.

Glucagon-like peptide-1 (GLP-1) has been proposed as a target for treatment of type 2 diabetes. GLP-1 has also been demonstrated to improve endothelial cell dysfunction in diabetic patients. Elevated plasminogen activator inhibitor type-1 [corrected] (PAI-1) levels have been implicated in endothelial cell dysfunction. The effect of GLP-1 on PAI-1 expression in vascular endothelial cells has not been explored. In a spontaneously transformed human umbilical vein endothelial cell (HUVEC) line, C11-spontaneously transformed HUVEC (STH) and primary HUVEC cells, GLP-1 treatment, in the presence of a dipeptidyl peptidase IV inhibitor, attenuated induction of PAI-1 protein and mRNA expression by tumour necrosis factor-alpha (TNF-alpha). GLP-1 also inhibited the effect of TNF-alpha on a reporter gene construct harbouring the proximal PAI-1 promoter. In addition, GLP-1 attenuated TNF-alpha-mediated induction of Nur77 mRNA and TNF-alpha-mediated binding of nuclear proteins (NPs) to the PAI-1, Nur77, cis-acting response element nerve growth factor induced clone B response element (NBRE). GLP-1 treatment also inhibited TNF-alpha-mediated induction of Akt phosphorylation. Taken together, these observations suggest that GLP-1 inhibits TNF-alpha-mediated PAI-1 induction in vascular endothelial cells, and this effect may involve Akt-mediated signalling events and the modulation of Nur77 expression and NP binding to the PAI-1 NBRE.

Gonadotroph adenoma in multiple endocrine neoplasia type 1.

OBJECTIVE: To describe a case of an in vivo follicle-stimulating hormone (FSH)-secreting gonadotroph adenoma in a man with multiple endocrine neoplasia type 1 (MEN 1) syndrome. METHODS: We present a retrospective case description and a discussion of the related literature. RESULTS: A 48-year-old man had progressively deteriorating visual acuity and bitemporal hemianopia, found to be attributable to a macroadenoma encircling both carotid arteries and compressing the optic chiasm. His libido and erectile function had been reduced for 2 years. The serum FSH level was substantially elevated at 31.1 IU/L (reference range, 1 to 10); alpha-subunit was elevated at 2.25 IU/L (reference range, 0.09 to 0.4); luteinizing hormone was normal at 4 IU/L (reference range, 1 to 10); total testosterone was low at 6.8 nmol/L (reference range, 9.5 to 35); and prolactin was slightly increased at 433 mU/L (reference range, 50 to 300). Transsphenoidal hypophysectomy was performed. Pituitary histopathologic examination showed a tumor with cytoplasmic granular FSH immunoreactivity. The patient had undergone parathyroidectomy for primary hyperparathyroidism 2 years before the current intervention. A family history of endocrine neoplasia was obtained of one sibling with a nonfunctioning pituitary adenoma, another sibling who had died of pancreatic carcinoma, and a third sibling, along with her son, who has primary hyperparathyroidism. Performance of genetic testing for MEN 1 revealed a nonsense mutation--R460X (nt7605C>T)--located on exon 10 of the MEN1 gene. CONCLUSION: We report an unusual case of clearly high circulating immunoreactive FSH due to a functioning FSH-secreting gonadotroph adenoma in a man with the MEN 1 syndrome.