Alamandine reduces leptin expression through the c-Src/p38 MAP kinase pathway in adipose tissue.

OBJECTIVE: Obesity is associated with an increased risk of diabetes mellitus, hypertension, and renal dysfunction. Angiotensin 1-7 and alamandine are heptameric renin angiotensin system peptide hormones. Further, alamandine levels increase with renal dysfunction. In the cardiovascular system, angiotensin 1-7 and alamandine produce similar improvements and counterbalance angiotensin II in regulating vascular function. We aimed to determine whether the effect of alamandine on leptin expression and secretion in adipocytes was similar to that of angiotensin 1-7. APPROACH AND RESULTS: We studied isolated peri-renal visceral adipose tissue and peri-renal isolated visceral adipocytes from male Wistar rats. Angiotensin II from 0.01 to 10nM had no effect on leptin expression. Angiotensin 1-7 (1 nM) increased leptin secretion and expression, whereas alamandine (1 nM) decreased leptin secretion and expression in adipose tissue and isolated adipocytes and reduced blood leptin levels in vivo. These effects were mediated by Gq, c-Src, p38 mitogen-activated protein, and IκB activation. Additionally, alamandine induced nitric oxide expression via inducible nitric oxidase synthase and plasminogen activator inhibitor 1 expression in adipose tissue and isolated adipocytes. CONCLUSIONS: Angiotensin 1-7 and alamandine produced opposing effects on leptin expression and secretion in adipose tissue. This result suggests that the action of Mas (angiotensin 1-7 receptor) and Mas-related G-protein coupled receptor D in adipocytes exhibited opposing actions similar to angiotensin II type 1 and type 2 receptors.

Angiotensin II Reduces Lipoprotein Lipase Expression in Visceral Adipose Tissue via Phospholipase C ß4 Depending on Feeding but Increases Lipoprotein Lipase Expression in Subcutaneous Adipose Tissue via c-Src.

Metabolic syndrome is characterized by visceral adiposity, insulin resistance, high triglyceride (TG)- and low high-density lipoprotein cholesterol-levels, hypertension, and diabetes-all of which often cause cardiovascular and cerebrovascular diseases. It remains unclear, however, why visceral adiposity but not subcutaneous adiposity causes insulin resistance and other pathological situations. Lipoprotein lipase (LPL) catalyzes hydrolysis of TG in plasma lipoproteins. In the present study, we investigated whether the effects of angiotensin II (AngII) on TG metabolism are mediated through an effect on LPL expression. Adipose tissues were divided into visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) for comparison. AngII accelerated LPL expression in SAT but, on the contrary, suppressed its expression in VAT. In both SAT and VAT, AngII signaled through the same type 1 receptor. In SAT, AngII increased LPL expression via c-Src and p38 MAPK signaling. In VAT, however, AngII reduced LPL expression via the Gq class of G proteins and the subsequent phospholipase C ß4 (PLCß4), protein kinase C ß1, nuclear factor κB, and inducible nitric oxide synthase signaling pathways. PLCß4 small interfering RNA experiments showed that PLCß4 expression is important for the AngII-induced LPL reduction in VAT, in which PLCß4 expression increases in the evening and falls at night. Interestingly, PLCß4 expression in VAT decreased with fasting, while AngII did not decrease LPL expression in VAT in a fasting state. In conclusion, AngII reduces LPL expression through PLCß4, the expression of which is regulated by feeding in VAT, whereas AngII increases LPL expression in SAT. The different effects of AngII on LPL expression and, hence, TG metabolism in VAT and SAT may partly explain their different contributions to the development of metabolic syndrome.

Constitutively active heat shock factor 1 enhances glucose-driven insulin secretion.

Weak pancreatic ß-cell function is a cause of type 2 diabetes mellitus. Glucokinase regulates insulin secretion via phosphorylation of glucose. The present study focused on a system for the self-protection of pancreatic cell by expressing heat shock factor (HSF) and heat shock protein (HSP) to improve insulin secretion without inducing hypoglycemia. We previously generated a constitutively active form of human HSF1 (CA-hHSF1). An adenovirus expressing CA-hHSF1 using the cytomegalovirus promoter was generated to infect mouse insulinoma cells (MIN6 cells). An adenovirus expressing CA-hHSF1 using a human insulin promoter (Ins-CA-hHSF1) was also generated to infect rats. We investigated whether CA-hHSF1 induces insulin secretion in MIN6 cells and whether Ins-CA-hHSF1 can improve blood glucose and serum insulin levels in healthy Wister rats and type 2 diabetes mellitus model rats. CA-hHSF1 expression increased insulin secretion 1.27-fold compared with the overexpression of wild-type hHSF1 in MIN6 cells via induction of HSP90 expression and subsequent activation of glucokinase. This mechanism is associated with activation of both glucokinase and neuronal nitric oxide synthase. Ins-CA-hHSF1 improved blood glucose levels in neonatal streptozotocin-induced diabetic rats. Furthermore, Ins-CA-hHSF1 reduced oral glucose tolerance testing results in healthy Wister rats because of an insulin spike at 15 minutes; however, it did not induce hypoglycemia. CA-hHSF1 induced insulin secretion both in vitro and in vivo. These findings suggest that gene therapy with Ins-CA-hHSF1 will be able to be used to treat patients with type 2 diabetes mellitus and impaired glucose tolerance without causing hypoglycemia at fasting.

Clinical significance of neutrophil apoptosis in peripheral blood of patients with type 2 diabetes mellitus.

UNLABELLED: Although neutrophils are essential components of the natural immune system, they have also been implicated in the pathogenesis of tissue injuries. We assessed the clinical significance of neutrophil apoptosis in the peripheral blood of patients with type 2 diabetes mellitus (T2DM). PATIENTS AND METHODS: The study included 52 patients with T2DM (30 men, 22 women). Control subjects were 16 healthy volunteers without diabetes (7 men, 9 women). Neutrophil apoptosis levels were measured active caspase-3 positive rate by flow cytometry. RESULTS: The mean rate of neutrophil apoptosis in patients with T2DM was 15.0% (95% confidence interval [CI]: 9.5% approximately 20.5%), while that in the control group was 5.8% (95% CI: 1.6% approximately 10.0%). There were significant negative correlations between neutrophil apoptosis rate and hemoglobin (Hb) A1c levels (r = -0.352, P < .01). The mean rate of neutrophil apoptosis in the patient group with the 3 major complications (diabetic retinopathy, nephropathy, and neuropathy) was 11.1% (95% CI: 5.5%-16.7%, n = 36) and that of another group without complications was 23.8% (95% CI: 11.4%-36.2%, n = 16). There was a significant difference between these 2 groups (P < .05). CONCLUSIONS: The neutrophil apoptosis rate in patients with T2DM was significantly correlated with HbA1C levels. The mean rate of neutrophil apoptosis in the patient group with 3 major diabetic complications remained lower than that in another patient group without complications. The inhibition of neutrophil apoptosis by chronic hyperglycemia is thought to promote tissue injury and to enhance the risk of microangiopathy.

HSF1 and constitutively active HSF1 improve vascular endothelial function (heat shock proteins improve vascular endothelial function).

We have been examining the role of heat shock factor 1 (HSF1) in the pleiotropic effects of statins. In parallel studies, we found that statin induces the nuclear translocation of HSF1 and that a decoy oligonucleotide encoding the heat shock element inhibits the statin-induced expression of heat shock protein 70, endothelial nitric oxide synthase (eNOS) and thrombomodulin. Also, in vascular endothelial cells, increases in the expression of human HSF1 corresponded with elevated steady-state levels of eNOS and thrombomodulin and reduced levels of endothelin-1 and plasminogen activator inhibitor-1. We also found that heat shock proteins induced eNOS and thrombomodulin expression and reduced PAI-1 and ET-1 expression. In particular, a combination of HSP70 and HSP90 strongly induced eNOS expression and reduced PAI-1 expression. In the current studies, we generated a constitutively active form of HSF1 and found that it is more effective than the wild-type HSF at inducing thrombomodulin and eNOS expression and decreasing endothelin-1 and plasminogen activator inhibitor-1 expression. These results show that the wild-type and constitutively active forms of HSF1 induce anticoagulation and relaxation factors in vascular endothelial cells and could therefore be used to treat cardiovascular disease.

Simvastatin induces heat shock factor 1 in vascular endothelial cells.

Statins not only reduce serum cholesterol but they also improve vascular endothelial function independent of their lipid-lowering effects. However, except for the mechanism of nitric oxide induction via calveolin, the physiologic basis for the pleiotropic effect of statins remains unknown. In the present study, we investigated the relationship between the effects of statins on vascular endothelial cell function and heat shock proteins. We found that, in vascular endothelial cells, simvastatin increased the steady-state levels of heat shock proteins 90 and 70, and heme oxygenase-1 and caused the nuclear translocation of heat shock factor 1. A decoy oligonucleotide encoding the heat shock element inhibited statin-induced expression of heat shock protein 70, endothelial nitric oxide synthase, and thrombomodulin. This decoy oligonucleotide also inhibited the ability of statin to reduce endothelin-1 and plasminogen activator inhibitor-1 expression. These results indicate that statins improve vascular endothelial function via heat shock factor 1, which may contribute to their ability to improve cardiovascular disease.

Type 2 diabetes mellitus complicated with smoldering myeloma and non-alcoholic steatohepatitis.

We report a 59-year-old woman with type 2 diabetes mellitus (DM) complicated with smoldering myeloma and non-alcoholic steatohepatitis. A diagnosis of smoldering myeloma was made on the basis of elevation of IgA, M-protein (type:IgA-lambda) and histological findings of bone marrow without bone lesion. As to liver dysfunction, anti-HBV, anti-HCV and a series of auto-immune antibody were negative. She had no alcohol drinking habit and histological findings showed pericellular fibrosis without fatty degeneration, suggesting liver cirrhosis due to non-alcoholic steatohepatitis (NASH). To date, there are no reports of cases with DM, NASH and myeloma. Particular attention may be necessary for these complications.

Hormone replacement therapy decreases insulin resistance and lipid metabolism in Japanese postmenopausal women with impaired and normal glucose tolerance.

OBJECTS: To investigate the effect of combined estrogen and progesterone therapy on insulin resistance (IR) and carbohydrate and lipid metabolism in postmenopausal women (PMW) with impaired (IGT) and normal glucose tolerance (NGT). METHODS: Sixteen Japanese PMW with IGT and 33 with NGT received daily oral hormone replacement therapy (HRT; 0.625 mg of conjugated equine estrogen plus 2.5 mg of medroxyprogesterone acetate) for 12 months. As controls, 13 Japanese PMW with IGT and 31 with NGT were enrolled and not treated by HRT. Fasting plasma glucose (FPG), fasting immunoreactive insulin (IRI), and IR were measured in each subject at study initiation and 12 months later. We used homeostasis model assessment (HOMA) to determine IR. RESULTS: FPG and HOMA IR were decreased in both HRT groups, and fasting IRI was reduced in the HRT-NGT group. In controls, FPG, fasting IRI, and HOMA IR were unaltered. Total and low-density lipoprotein cholesterol were decreased and high-density lipoprotein cholesterol was increased in both HRT groups, but triglyceride was unchanged. In controls, lipid metabolism was unaltered. CONCLUSION: HRT decreased IR and improved carbohydrate and lipid metabolism in Japanese PMW with IGT and NGT. These beneficial effects argue for the use of HRT in PMW with IGT as well as NGT.