iSGLT2 y su potencial efecto nefroprotector en pacientes con diabetes mellitus 2 / iSGLT2 and its potential nephroprotector effect in patients with diabetes mellitus 2

Resumen: La diabetes mellitus 2 es una epidemia mundial, aunado a esto, la nefropatía diabética se ha convertido en la principal causa de insuficiencia renal en etapa terminal. En los pacientes con diabetes mellitus 2 existe sobreexpresión de los cotransportadores de glucosa ligados a la vía del sodio tipo 2 (SGLT2) que contribuyen al mantenimiento de la hiperglucemia. Por tanto, los inhibidores de este transportador representan un tratamiento innovador independiente de la acción de la insulina o la función de las células beta pancreáticas. En estudios recientes se ha demostrado que los iSGLT2 tienen efectos benéficos en la microvasculatura, en especial en la progresión de la nefropatía diabética. Este efecto no sólo se debe a la mejora del control glucémico, sino también a efectos directos en el riñón. Los iSGLT2, al inducir la glucosuria, revierten la glucotoxicidad renal. En estudios experimentales se ha observado que, además, se reduce la hiperfiltración, así como los marcadores inflamatorios y fibróticos. También se ha visto reducción del volumen circulante efectivo y aumento en la actividad de bloqueadores del sistema renina-angiotensina-aldosterona (bloqueadores RAA) circulantes, creando así un efecto nefroprotector.

Abstract: Type 2 diabetes mellitus 2 (DM2) is already a worldwide epidemic, in addition, diabetic nephropathy has become the leading cause of end-stage renal failure. In patients with DM2 there is an increased expression of the sodium-glucose cotransporters 2 (SGLT2) that contribute to the maintenance of hyperglycemia. Therefore, the inhibitors of this transporter represent an innovative therapy independent of the action of insulin or the function of pancreatic beta cells. Recent studies have shown that iSGLT2 have beneficial effects on microvasculature, especially in the progression of diabetic nephropathy. This effect is due not only to improved glycemic control but also to direct effects on the kidney. iSGLT2 induce glycosuria to reverse renal glucotoxicity. In experimental studies it has been observed that, in addition, hyper-filtration as well as inflammatory and fibrotic markers are reduced. There has also been a reduction in effective circulating volume and an increase in the activity of circulating renin-angiotensin-aldosterone system blockers (RAA blockers), thus creating a nephroprotective effect.

Effects of Apelin on glucose toxicity and islet cells PDX-1 expression / 重庆医学

Objective To study the effects of Apelin on glucose toxicity and islet cells PDX-1 protein expression.Methods The islet β cell line NIT-1 cells were incubated in the medium containing different glucose concentrations(normal glucose concentration group 5.6 mmol/L,high glucose concentration group 16.7 mmol/L,extremely high glucose concentration group 33.3 mmol/L) and +/-Apelin-36 respectively for 3 d.Then the basic insulin secretion amount of islet cells and their secretion amount after glucose stimulation were detected.The intracellular insulin content and the PDX-1 protein and mRNA expression were detected.Results Compared with the normal glucose group,the basic insulin secretion,secretion after stimulation and intracellular insulin in the high glucose group and extremely high glucose group were significantly decreased and PDX-1 protein expression was declined(P＜ 0.05);compared with non-adding Apelin group,the basic insulin secretion,secretion after stimulation and intracellular insulin in the adding Apelin high glucose group and extremely high glucose group were significantly decreased and PDX-1 protein expression was decreased(P＜0.05);the insulin level in islet cells of 6 groups was positively correlated with PDX-1 protein expression and had no correlation with PDX-1 mRNA expression.Conclusion Apelin may participate in the glucose toxic effect by decreasing PDX-1 protein expression,causes the decrease of insulin secretion,thus plays a role in the pathogenesis of diabetes.

Paradox of using intensive lowering of blood glucose in diabetics and strategies to overcome it and decrease cardiovascular risks / 中国结合医学杂志

Hyperglycemia significantly increases the risk of cardiovascular disease (CVD) in diabetics. However, it has been shown by a series of large scale international studies that intensive lowering of blood glucose levels not only has very limited benefits against cardiovascular problems in patients, but may even be harmful to patients at a high risk for CVD and/or poor long-term control of blood glucose levels. Therefore, Western medicine is faced with a paradox. One way to solve this may be administration of Chinese herbal medicines that not only regulate blood glucose, blood fat levels and blood pressure, but also act on multiple targets. These medicines can eliminate cytotoxicity of high glucose through anti-inflammatory and anti-oxidant methods, regulation of cytokines and multiple signaling molecules, and maintenance of cell vitality and the cell cycle, etc. This allows hyperglycemic conditions to exist in a healthy manner, which is called "harmless hyperglycemia" Furthermore, these cardiovascular benefits go beyond lowering blood glucose levels. The mechanisms of action not only avoid cardiovascular injury caused by intensive lowering of blood glucose levels, but also decrease the cardiovascular dangers posed by hyperglycemia.

Effect of high glucose toxicity on JNK pathway, cell viability and apoptosis in pancreatic β-cell line INS-1 / 中国病理生理杂志

AIM: To investigate the effect of high glucose toxicity on JNK pathway and cell function of INS-1 cells.METHODS: Cultured INS-1 cells with or without IGF-1 exposure, were treated with glucose at 3 concentrations (5.6 mmol/L, 11.2 mmol/L and 33.3mmol/L), respectively. MTT was used to measure the cell viability. Apoptosis was determined by immuno-fluorescence and flow-cytometry analysis. The serine 270 phosphorylation of IRS and phosphorylation of JNK in INS-1 cells were detected in the presence or absence of SP600125 treatment.RESULTS: The cell viability decreased and apoptosis increased with elevated glucose concentrations. The percentage of apoptosis cells was 11.3% in 5.6 G group, 12.7% in 11.2 G group and 28.2% in 33.3 G group. There was remarkable increase in apoptosis in 33.3 G group with a 2.49-fold increase to the cells in the basal 5.6 mmol/L glucose. High glucose activated the serine 270 phosphorylation of IRS correlates with JNK phosphorylation in INS-1 cells. Using Western blotting analysis, the levels of JNK phosphorylation were 3.33 fold increased and serine 270 phosphorylation of IRS was 1.17 fold increased in 33.3 G group compared to 11.2 G group (P<0.01). IGF-1 treatment inhibited phosphorylation of JNK and IRS. SP600125 treatment completely blocked JNK phosphorylation in 11.2 G group and reduced JNK phosphorylation by 90% in 33.3 G group. In addition, SP600125 treatment partly reduced serine 270 phosphorylation of IRS by 88.3% in 11.2 G group and 80% in 33.3 G group, the viability of INS-1 cells increased and the apoptosis decreased.CONCLUSION: The toxicity of chronic high glucose, which inhibits the cells viability and induces the cell apoptosis, might be related to suppress IRS signal by activating the JNK pathway. Blocking the JNK pathway might relieve the effect of glucose toxicity to the β cell function by improving the IRS signal pathway.

Glucose Toxicity and Pancreatic Beta Cell Dysfunction in Type 2 Diabetes / 당뇨병

The adverse effects of prolonged exposure of pancreatic islets to supraphysiologic glucose concentrations (i.e. glucose toxicity) is mediated at least in part by glucose oxidation and the subsequent generation of reactive oxygen species (ROS) that can impair insulin gene expression and beta cell function. Multiple biochemical pathways and mechanisms of action for glucose toxicity have been suggested. These include glucose autoxidation, protein kinase C activation, methylglyoxal formation and glycation, hexosamine metabolism, sorbitol formation, and oxidative phosphorylation. There are many potential mechanisms whereby excess glucose metabolites traveling along these pathways might cause beta cell damage. However, all these pathways have in common the formation of reactive oxygen species that, in excess and over time, cause chronic oxidative stress, which in turn causes defective insulin gene expression and insulin secretion as well as increased apoptosis. The intracellular peroxide levels of the pancreatic islets (INS-1 cells, rat islets) by flow cytometry were increased in the high glucose media compared to 5.6 mM glucose media. The insulin, MafA, PDX-1 mRNA levels and glucose stimulated insulin secretion (GSIS) were decreased in high glucose media compared to 5.6 mM glucose media. The HO-1 seems to mediate the protective response of pancreatic islets against the oxidative stress that is due to high glucose conditions. Also, we observed decreased glutathione level, gamma-GCS expression and increased oxidized LDL, malondialdehyde level at leukocytes and mesothelial cells from patients with Korean Type 2 Diabetes (esp, poorly controlled patients). In conclusion, this pathophysiologic sequence sets the scene for considering antioxidant therapy as an adjunct in the management of diabetes, especially type 2 Diabetes.

A Protective Role for Heme Oxygenase-1 in INS-1 Cells and Rat Islets that are Exposed to High Glucose Conditions

Heme oxygenase-1 (HO-1) has been described as an inducible protein that is capable of cytoprotection via radical scavenging and the prevention of apoptosis. Chronic exposure to hyperglycemia can lead to cellular dysfunction that may become irreversible over time, and this process has been termed glucose toxicity. Yet little is known about the relation between glucose toxicity and HO-1 in the islets. The purposes of the present study were to determine whether prolonged exposure of pancreatic islets to a supraphysiologic glucose concentration disrupts the intracellular balance between reactive oxygen species (ROS) and HO-1, and so this causes defective insulin secretion; we also wanted to evaluate a protective role for HO-1 in pancreatic islets against high glucose levels. The intracellular peroxide levels of the pancreatic islets (INS-1 cell, rat islet) were increased in the high glucose media (30 mM glucose or 50 mM ribose). The HO-1 expression was induced in the INS-1 cells by the high glucose levels. Both the HO-1 expression and glucose stimulated insulin secretion (GSIS) was decreased simultaneously in the islets by treatment of the HO-1 antisense. The HO-1 was upregulated in the INS-1 cells by hemin, an inducer of HO-1. And, HO-1 upregulation induced by hemin reversed the GSIS in the islets at a high glucose condition. These results suggest HO-1 seems to mediate the protective response of pancreatic islets against the oxidative stress that is due to high glucose conditions.

Cyto-protective Effects of Aqueous Extract from the Gall of Rhus chinensis on Pancreatic Beta-cell / 대한해부학회지

We have previously reported that aqueous extract of gall from Rhus chinensis, known as "Obaeja", inhibited rat intestinal alpha-glucosidase and suppressed postprandial hyperglycemia by delaying digestion and absorption of intestinal carbohydrate (Shim et al., 2003). This led us to speculate that obaeja could be involved in ameliorating beta-cell injury by lowering glucotoxicity. In the present study, we thus examined the protective effect of obaeja on pancreatic beta-cell damage along with its anti-diabetic effect in streptozotocin-induced animal models. Streptozotocin was administered to rat pups (neonate/STZ model), or to adult rats with a lower dose using osmotic pump (osmotic pump/STZ model) for inducing beta cell death and diabetes. Obaeja was given to those rat pups after weaning in neonate/STZ model, or 2 weeks before subcutaneous implantation of osmotic pump to rats of the other latter model. In the diabetic control rats of the neonate/STZ model, which were not fed with obaeja, some pancreatic islets demonstrated a destruction of beta cell mass with insulitis 2 weeks after weaning, while some larger and irregular islets were formed by proliferation of alpha cells. In particular, we found some pancreatic lobules showing a severe inflammation and degeneration of islet and acinar tissues in this model. Islets in these inflammatory lobules were smaller in size with only few cells. In contrast, any inflammatory responses and insulitis were not observed in pancreas of the rats fed obaeja in this model. The islets in those rats maintained their normal profiles and islet cell population. Such anti-cytotoxic effect was also monitored in the diabetic rats of osmotic pump/STZ model. Especially, occurrence of hyperglycemia in the obaeja fed rats was delayed by 25~30 days than that of diabetic control rats in this model. Taken together, these results imply that regulation of postprandial blood glucose level by obaeja feeding may ameliorate a secondary injury caused by glucotoxicity.

Effect of short-term intensive insulin treatment on hyperglycemic toxicity / 中华内分泌代谢杂志

Forty-one type 2 diabetic patients with fasting plasma glucose≥15 mmol/L and postprandial plasma glucose≥16.8 mmol/L underwent short-term intensive insulin treatment (IIT). Glucose load tests were performed before and after treatment in these patients and proinsulin and C peptide were assayed by RIA. The results showed that IIT decreased the levels of fasting and postprandial proinsulin and improved the ? cell function.

Effect of high glucose toxicity on JNK pathway,cell viability and apoptosis in pancreatic ?-cell line INS-1 / 中国病理生理杂志

AIM:To investigate the effect of high glucose toxicity on JNK pathway and cell function of INS-1 cells.METHODS: Cultured INS-1 cells with or without IGF-1 exposure,were treated with glucose at 3 concentrations (5.6 mmol/L,11.2 mmol/L and 33.3mmol/L),respectively. MTT was used to measure the cell viability. Apoptosis was determined by immuno-fluorescence and flow-cytometry analysis. The serine 270 phosphorylation of IRS and phosphorylation of JNK in INS-1 cells were detected in the presence or absence of SP600125 treatment.RESULTS: The cell viability decreased and apoptosis increased with elevated glucose concentrations. The percentage of apoptosis cells was 11.3% in 5.6 G group,12.7% in 11.2 G group and 28.2% in 33.3 G group. There was remarkable increase in apoptosis in 33.3 G group with a 2.49-fold increase to the cells in the basal 5.6 mmol/L glucose. High glucose activated the serine 270 phosphorylation of IRS correlates with JNK phosphorylation in INS-1 cells. Using Western blotting analysis,the levels of JNK phosphorylation were 3.33 fold increased and serine 270 phosphorylation of IRS was 1.17 fold increased in 33.3 G group compared to 11.2 G group (P

Improvement of high glucose toxicity-induced insulin desensitivity by nitric oxide in diabetic rats / 中华内分泌代谢杂志

Objective To observe whether nitric oxide (NO) improves high glucose toxicity induced insulin resistance in streptozotocin (STZ) induced diabetic rats. Methods The changes of metabolic clearance rate for glucose (MCR), as the index of insulin effect, were observed in 24 STZ induced diabetic rats and 24 normal rats in awake condition treated by sodium nitroprusside (SNP), N G monomethyl L arginine (LNMMA), adenosine or saline duringeuglycemichyperinsulinemiaclampprocedure.Results MCR in saline treated diabetic rats 〔(7.2?0.8)ml?kg -1 ?min -1 〕 wassignificantlylowerthanthat in normol control rats 〔(18.0?1.8)ml?kg -1 ?min -1 , P