1型糖尿病的基因治疗进展

尽管皮下注射胰岛素、口服降糖药等可以缓解糖尿病患者的高血糖,但是这些治疗措施只是暂时性的,并不能从根本上彻底治疗糖尿病以及阻止其他并发症的发生。随着人们对糖尿病本质的深层次揭示和现代分子生物学手段的发展,针对由胰岛素分泌缺乏引起的1型糖尿病(T1D)基因治疗手段逐渐丰富。总结了胰岛素替代基因的直接导入,刺激新的β细胞再生以及阻止胰岛β细胞的自身免疫,抑制胰岛β细胞的凋亡等1型糖尿病的基因治疗新进展,并展望其未来发展方向。     

IRS-1 regulation in health and disease

The global incidence of diabetes is increasing at epidemic rates. Estimates suggest there are currently 150 million people with diabetes and this number is expected to double in the next 20 years. Type 2 diabetes accounts for 95% of all cases and is characterized in part by impaired sensitivity to insulin or 'insulin resistance'. Defects in the insulin signalling pathways underpin this resistance. In the current article we discuss the regulation of Insulin Receptor Substrate-1 (IRS-1), a protein that plays a pivotal role in insulin signalling and whose function is impaired in subjects with insulin resistance. Coordination of IRS-1 function is multi-faceted, involving phosphorylation of IRS-1 at multiple serine/threonine residues. This controls many aspects of IRS-1, including its interaction with the insulin receptor and subsequent tyrosine phosphorylation, as well as its subcellular distribution and targeting for degradation by the proteasome. Such tight control ensures appropriate transduction and attenuation of the insulin signal, thereby regulating insulin action in healthy individuals. Emerging evidence indicates that 'diabetogenic factors' associated with insulin resistance, such as TNFalpha and elevated circulating fatty acids, impact on insulin signalling at the level of IRS-1 serine/threonine phosphorylation. The expression and/or activity of several kinases, such as IkappaB kinase beta (IKKbeta) and salt-induced kinase 2 (SIK2), and the phosphorylation of IRS-1 at key sites, such as Ser307 and Ser789, are increased in states of insulin resistance. Identifying the pathways by which such factors activate these and other kinases, and defining the precise roles of specific serine/ threonine phosphorylation events in IRS-1 regulation, represent important goals which may eventually provide a rationale for therapeutic intervention.     

Seven days of aerobic exercise training improves conduit artery blood flow following glucose ingestion in patients with type 2 diabetes

The vasodilatory effects of insulin account for up to 40% of insulin-mediated glucose disposal; however, insulin-stimulated vasodilation is impaired in individuals with type 2 diabetes, limiting perfusion and delivery of glucose and insulin to target tissues. To determine whether exercise training improves conduit artery blood flow following glucose ingestion, a stimulus for increasing circulating insulin, we assessed femoral blood flow (FBF; Doppler ultrasound) during an oral glucose tolerance test (OGTT; 75 g glucose) in 11 overweight or obese (body mass index, 34 ± 1 kg/m2), sedentary (peak oxygen consumption, 23 ± 1 ml·kg?1·min?1) individuals (53 ± 2 yr) with non-insulin-dependent type 2 diabetes (HbA1c, 6.63 ± 0.18%) before and after 7 days of supervised treadmill and cycling exercise (60 min/day, 60-75% heart rate reserve). Fasting glucose, insulin, and FBF were not significantly different after 7 days of exercise, nor were glucose or insulin responses to the OGTT. However, estimates of whole body insulin sensitivity (Matsuda insulin sensitivity index) increased (P < 0.05). Before exercise training, FBF did not change significantly during the OGTT (1 ± 7, -7 ± 5, 0 ± 6, and 0 ± 5% of fasting FBF at 75, 90, 105, and 120 min, respectively). In contrast, after exercise training, FBF increased by 33 ± 9, 39 ± 14, 34 ± 7, and 48 ± 18% above fasting levels at 75, 90, 105, and 120 min, respectively (P < 0.05 vs. corresponding preexercise time points). Additionally, postprandial glucose responses to a standardized breakfast meal consumed under "free-living" conditions decreased during the final 3 days of exercise (P < 0.05). In conclusion, 7 days of aerobic exercise training improves conduit artery blood flow during an OGTT in individuals with type 2 diabetes.     

Bcl-2 proteins in diabetes: mitochondrial pathways of β-cell death and dysfunction

Diabetes is a metabolic disease affecting nearly 300 million individuals worldwide. Both types of diabetes (1 and 2) are characterized by loss of functional pancreatic β-cell mass causing different degrees of insulin deficiency. The Bcl-2 family has a double-edged effect in diabetes. These proteins are crucial controllers of the mitochondrial pathway of β-cell apoptosis induced by pro-inflammatory cytokines or lipotoxicity. In parallel, some Bcl-2 members also regulate glucose metabolism and β-cell function. In this review, we describe the role of Bcl-2 proteins in β-cell homeostasis and death. We focus on how these proteins interact, their contribution to the crosstalk between endoplasmic reticulum stress and mitochondrial permeabilization, their context-dependent usage following different pro-apoptotic stimuli, and their role in β-cell physiology.     

Sweet Killing in Obesity and Diabetes: The Metabolic Role of the BH3-only Protein BIM

Diabetes is a metabolic disorder affecting more than 400 million individuals and their families worldwide. The major forms of diabetes (types 1 and 2) are characterized by pancreatic β-cell dysfunction and, in some cases, loss of β-cell mass causing hyperglycemia due to absolute or relative insulin deficiency. The BCL-2 homology 3 (BH3)-only protein BIM has a wide role in apoptosis induction in cells. In this review, we describe the apoptotic mechanisms mediated by BIM activation in β cells in obesity and both forms of diabetes. We focus on molecular pathways triggered by inflammation, saturated fats, and high levels of glucose. Besides its role in cell death, BIM has been implicated in the regulation of mitochondrial oxidative phosphorylation and cellular metabolism in hepatocytes. BIM is both a key mediator of pancreatic β-cell death and hepatic insulin resistance and is thus a potential therapeutic target for novel anti-diabetogenic drugs. We consider the implications and challenges of targeting BIM in the treatment of the disease.     

Regulating insulin signaling and beta-cell function through IRS proteins

Diabetes mellitus is a complex disorder that arises from various causes, including dysregulated glucose sensing and impaired insulin secretion (maturity onset diabetes of youth, MODY), autoimmune-mediated beta-cell destruction (type 1), or insufficient compensation for peripheral insulin resistance (type 2). Type 2 diabetes is the most prevalent form that usually occurs at middle age; it afflicts more than 30 million people over the age of 65, but is appearing with greater frequency in children and adolescents. Dysregulated insulin signaling exacerbated by chronic hyperglycemia promotes a cohort of systemic disorders--including dyslipidemia, hypertension, cardiovascular disease, and female infertility. Understanding the molecular basis of insulin resistance can prevent these disorders and their inevitable progression to type 2 diabetes.     

低血糖与2型糖尿病

糖尿病（DM）是一种慢性终身性疾病,目前已成为严重威胁人类健康的世界性公共卫生问题,2型糖尿病患者也逐渐增加。流行病学调查显示,目前全球大约有近2亿糖尿病患者,其中2型糖尿病占90%～95%。2型糖尿病发病机理是胰岛素分泌的相对或绝对不足伴有或不伴有胰岛素抵抗,持续的高血糖可严重抑制胰岛功能。严格的血糖控制能够延缓糖尿病慢性并发症的发生和发展,延长了患者的预期寿命。但是随着血糖控制达标,发生低血糖的危险性增加了,低血糖不仅严重阻碍了良好血糖控制,而且严重低血糖还是2型糖尿病致死、致残的重要原因。本文探讨2型糖尿病患者治疗中低血糖发生的原因、诱发因素以及可能的解决方案。     

Metallo-allixinate complexes with anti-diabetic and anti-metabolic syndrome activities

Metabolic syndrome and the accompanied diabetes mellitus are both important diseases worldwide due to changes of lifestyle and eating habits. The number of patients with diabetes worldwide is estimated to increase to 300 million by 2025 from 150-220 million in 2010. There are two main types of diabetes. In type 1 diabetes, caused by destruction of pancreatic β-cells resulting in absolute deficiency of intrinsic insulin secretion, the patients require exogenous insulin injections several times a day. In type 2 diabetes, characterized by insulin resistance and abnormal insulin secretion, the patients need exercise, diet control and/or several types of hypoglycemics. The idea of using metal ions for the treatment of diabetes originates from the report in 1899. The research on the role of metal ions that may contribute to the improvement of diabetes began. The orally active metal complexes containing vanadyl (oxidovanadium(iv)) ion and cysteine or other ligands were first proposed in 1990, and a wide class of vanadium, copper and zinc complexes was found to be effective for treating diabetes in experimental animals. We noticed a characteristic compound, allixin, which is a non-sulfur component in dry garlic. Its vanadyl and zinc complexes improved both types of diabetes following oral administration in diabetic animals. We then developed a new zinc complex with thioxoallixin-N-methyl (tanm), which is both a sulfur and N-methyl derivative of allixin, and found that this complex improves not only diabetes but also metabolic syndrome. Furthermore, new zinc complexes inspired from the zinc-tanm were prepared; one of them exceeded the activity of zinc-tanm. The mechanism of such complexes was studied in adipocytes. We describe here the usefulness of the development of metal-based complexes in the context of potential therapeutic application for diabetes and metabolic syndrome.     

Cellular immunity in insulin-dependent diabetes mellitus (type 1)

Cell-mediated immunity was investigated with T-cell blastic transformation stimulated by phytohaemagglutinin and/or insulin in patients with diabetes mellitus type 1. T-cell blastic transformation was determined in the whole blood by the intake of labelled thymidine intake by the lymphocytic DNA. Healthy individuals and patients with diabetes mellitus type 2 served as control groups. It was found that T-cell blastic transformation stimulated with phytohaemagglutinin is markedly diminished in patients with diabetes mellitus type 1 and to a lesser degree in patients with diabetes mellitus type 2. Insulin increased T-cell blastic transformation in insulin-dependent diabetic patients but has no effect in diabetes mellitus type 2. The obtained results suggest that induction and central phases of the cell-mediated immunological response are diminished in diabetes mellitus independently on its type. Such disorders may have different etiology depending on the type of diabetes mellitus.     

Glycaemic effects of incretins in Type 1 diabetes mellitus: a concise review, with emphasis on studies in humans

The remission phase of Type 1 diabetes mellitus is associated with substantial recovery of beta-cell function and with marked improvement of endogenous insulin responses to meals in the early months after diagnosis, accompanied by little or no improvement in the insulin response to parenteral glucose, suggesting that the incretin function may be important in glycaemic regulation in this phase of diabetes. Preservation of the insulin response to parenteral glucagon-like peptide-1 (GLP-1), contrasting with lack of stimulation of insulin secretion by the other known incretin gastric inhibitory polypeptide (GIP), prompted studies with exogenous GLP-1 in recent-onset Type 1 diabetes. These studies showed substantial reduction of glycaemic excursions after ingestion of mixed nutrients during intravenous infusion of GLP-1 without administration of insulin, in subjects with a range of endogenous secretion of insulin in response to meals as demonstrated by blood levels of the insulin-connecting peptide (CP). These effects were independent of stimulation of blood levels of CP and were reproduced in volunteers with no endogenous release of CP in response to meals. The glycaemic effects were associated with inhibition of abnormal rises of blood levels of glucagon, and with suppression of endogenous release of human pancreatic polypeptide (HPP), by GLP-1. It was hypothesized that a major component of the glycaemic effect is attributable to the known action of GLP-1 to inhibit gastric emptying and to inhibit glucagon secretion. Studies of the effects of GLP-1 agonists (GLP-1 and exendin-4) given together with established insulin doses before a meal supported the hypothesis. The more prolonged actions of exendin-4 were accompanied by greater and more prolonged reduction of glycaemic effects of ingestion of meals in volunteers with CP-negative Type 1 diabetes mellitus, during intensive insulin therapy, in whom delay of gastric emptying was confirmed by studies of blood levels of acetaminophen ingested with the meals. Side effect-free doses of exendin-4 given together with insulin in volunteers with CP-negative Type 1 diabetes receiving continuing intensive insulin therapy demonstrated the capacity of this combination therapy to normalize blood glucose levels after ingestion of meals that were consistent with the dietary program of the volunteers, without apparent increased risk of hypoglycaemia within a normal between-meals interval. It is suggested that further and more prolonged studies of the use of long-acting GLP-1 agonists as congeners with insulin in Type 1 diabetes mellitus are indicated.     

Zinc Supplementation Does Not Affect Glucagon Response to Intravenous Glucose and Insulin Infusion in Patients with Well-Controlled Type 2 Diabetes

Glucagon dysregulation is an essential component in the pathophysiology of type 2 diabetes. Studies in vitro and in animal models have shown that zinc co-secreted with insulin suppresses glucagon secretion. Zinc supplementation improves blood glucose control in patients with type 2 diabetes, although there is little information about how zinc supplementation may affect glucagon secretion. The objective of this study was to evaluate the effect of 1-year zinc supplementation on fasting plasma glucagon concentration and in response to intravenous glucose and insulin infusion in patients with type 2 diabetes. A cross-sectional study was performed after 1-year of intervention with 30 mg/day zinc supplementation or a placebo on 28 patients with type 2 diabetes. Demographic, anthropometric, and biochemical parameters were determined. Fasting plasma glucagon and in response to intravenous glucose and insulin infusion were evaluated. Patients of both placebo and supplemented groups presented a well control of diabetes, with mean values of fasting blood glucose and glycated hemoglobin within the therapeutic goals established by ADA. No significant differences were observed in plasma glucagon concentration, glucagon/glucose ratio or glucagon/insulin ratio fasting, after glucose or after insulin infusions between placebo and supplemented groups. No significant effects of glucose or insulin infusions were observed on plasma glucagon concentration. One-year zinc supplementation did not affect fasting plasma glucagon nor response to intravenous glucose or insulin infusion in well-controlled type 2 diabetes patients with an adequate zinc status.     

A randomized, double-blind, placebo-controlled trial to assess safety and tolerability during treatment of type 2 diabetes with usual diabetes therapy and either Cycloset™ or placebo

Background

Cycloset? is a quick-release formulation of bromocriptine mesylate, a dopamine agonist, which in animal models of insulin resistance and type 2 diabetes acts centrally to reduce resistance to insulin- mediated suppression of hepatic glucose output and tissue glucose disposal. In such animals, bromocriptine also reduces hepatic triglyceride synthesis and free fatty acid mobilization, manifesting decreases in both plasma triglycerides and free fatty acids. In clinical trials, morning administration of Cycloset? either as monotherapy or adjunctive therapy to sulfonylurea or insulin reduces HbA1c levels relative to placebo by 0.55–1.2. Cycloset? therapy also reduces plasma triglycerides and free fatty acid by approximately 25% and 20%, respectively, among those also receiving sulfonylurea therapies. The effects of once-daily morning Cycloset? therapy on glycemic control and plasma lipids are demonstrable throughout the diurnal portion of the day (7 a.m. to 7 p.m.) across postprandial time points.

Methods/Design

3,095 individuals were randomized in a 2:1 ratio into a one year trial aimed to assess the safety and efficacy of Cycloset? compared to placebo among individuals receiving a variety of treatments for type 2 diabetes. Eligibility criteria for this randomized placebo controlled trial included: age 30–80, HbA1c ≤ 10%, diabetes therapeutic regimen consisting of diet or no more than two hypoglycemic agents or insulin with or without one additional oral agent (usual diabetes therapy; UDT). The primary safety endpoint will test the hypothesis that the rate of all-cause serious adverse events after one year of usual diabetes therapy (UDT) plus Cycloset? is not greater than that for UDT plus placebo by more than an acceptable margin defined as a hazard ratio of 1.5 with a secondary endpoint analysis of the difference in the rate of serious cardiovascular events, (myocardial infarction, stroke, coronary revascularization or hospitalization for or angina or congestive heart failure). Efficacy analyses will evaluate effects of Cycloset? versus placebo on change from baseline in HbA1c, fasting glucose, body weight, waist circumference, blood pressure and plasma lipids.

Discussion

This study will extend the current data on Cycloset? safety, tolerability and efficacy in individuals with type 2 diabetes to include its effects in combination with thiazolodinediones, insulin secretagogues, metformin, alpha-glucosidase inhibitors and exogenous insulin regimens.

Trial registration

clinical trials.gov NCT00377676     

Insulin sensitivity after maximal and endurance resistance training

The purpose of the study was to compare the effects of maximal resistance training (MRT) vs. endurance resistance training (ERT) on improvements in insulin levels and glucose tolerance in overweight individuals at risk of developing type 2 diabetes. Eighteen participants with baseline values suggesting impaired glucose tolerance were randomly assigned to 1 of 2 groups. Group 1 engaged in supervised MRT (Bernstein inverted pyramid system: 5 × 3-4, 60-85% 1 repetition maximum [1RM]), 3 d·wk(-1) over 4 months, whereas members of group 2 acted as controls. Later, group 2 engaged in supervised ERT (3 × 12-15, 45-65% 1RM), 3 d·wk(-1) over a 4 month period with the 2 prebaselines as controls. Both interventions consisted of 8 exercises that included the entire body. Glucose (fasting and 2-hour test), insulin and C-peptide measures were assessed from pre to post in both groups. The MRT led to reduced blood levels of 2-hour glucose (p = 0.044) and fasting C-peptide (p = 0.023) and decreased insulin resistance (p = 0.040). The ERT caused a significant reduction in the blood levels of insulin (p = 0.023) and concomitant positive effects on % insulin sensitivity (p = 0.054) and beta-cell function (p = 0.020). The findings indicate that both MRT and ERT lead to decreased insulin resistance in people with a risk of developing type 2 diabetes; MRT led to a greater increase in glucose uptake capacity (in muscles), whereas ERT led to greater insulin sensitivity, supporting the recommendation of both MRT and ERT as primary intervention approaches for individuals at a risk of developing type 2 diabetes.     

Quantitative Measurement of GLUT4 Translocation to the Plasma Membrane by Flow Cytometry

Glucose is the main source of energy for the body, requiring constant regulation of its blood concentration. Insulin release by the pancreas induces glucose uptake by insulin-sensitive tissues, most notably the brain, skeletal muscle, and adipocytes. Patients suffering from type-2 diabetes and/or obesity often develop insulin resistance and are unable to control their glucose homeostasis. New insights into the mechanisms of insulin resistance may provide new treatment strategies for type-2 diabetes.The GLUT family of glucose transporters consists of thirteen members distributed on different tissues throughout the body¹. Glucose transporter type 4 (GLUT4) is the major transporter that mediates glucose uptake by insulin sensitive tissues, such as the skeletal muscle. Upon binding of insulin to its receptor, vesicles containing GLUT4 translocate from the cytoplasm to the plasma membrane, inducing glucose uptake. Reduced GLUT4 translocation is one of the causes of insulin resistance in type-2 diabetes^2,3.The translocation of GLUT4 from the cytoplasm to the plasma membrane can be visualized by immunocytochemistry, using fluorophore-conjugated GLUT4-specific antibodies.Here, we describe a technique to quantify total amounts of GLUT4 translocation to the plasma membrane of cells during a chosen duration, using flow cytometry. This protocol is rapid (less than 4 hours, including incubation with insulin) and allows the analysis of as few as 3,000 cells or as many as 1 million cells per condition in a single experiment. It relies on anti-GLUT4 antibodies directed to an external epitope of the transporter that bind to it as soon as it is exposed to the extracellular medium after translocation to the plasma membrane.     

Chromium metabolism and its role in disease processes in man

Chromium is an essential element required for normal carbohydrate and lipid metabolism. Insufficient dietary Cr has been linked to maturity-onset diabetes and cardiovascular diseases. The dietary Cr intake of most individuals is considerably less than the suggested safe and adequate intake. Consumption of refined foods, including simple sugars, exacerbates the problem of insufficient dietary Cr since these foods are not only low in dietary Cr but also enhance additional Cr losses. Chromium losses are also increased due to pregnancy, strenuous exercise, infection, physical trauma and other forms of stress. Supplementation of Cr to normal free-living individuals often leads to significant improvements in glucose tolerance, serum lipids including high-density lipoprotein cholesterol, insulin and insulin binding. Chromium also tends to normalize blood sugar. Chromium supplementation of subjects with elevated blood sugar following a glucose load leads to a decrease in blood sugar while hypoglycemics respond to supplemental Cr by an increase in hypoglycemic glucose values, increased insulin binding and alleviation of hypoglycemic symptoms. In summary, dietary intake of Cr is suboptimal and this is exacerbated by increased Cr losses due to stress and certain refined foods including simple sugars that enhance Cr losses. Supplemental Cr is associated with improvements of risk factors associated with maturity-onset diabetes and cardiovascular diseases.     

Genetic predisposition for Type 2 diabetes, but not for overweight/obesity, is associated with a restricted adipogenesis

Background

Development of Type 2 diabetes, like obesity, is promoted by a genetic predisposition. Although several genetic variants have been identified they only account for a small proportion of risk. We have asked if genetic risk is associated with abnormalities in storing excess lipids in the abdominal subcutaneous adipose tissue.

Methodology/Principal Findings

We recruited 164 lean and 500 overweight/obese individuals with or without a genetic predisposition for Type 2 diabetes or obesity. Adipose cell size was measured in biopsies from the abdominal adipose tissue as well as insulin sensitivity (HOMA index), HDL-cholesterol and Apo AI and Apo B. 166 additional non-obese individuals with a genetic predisposition for Type 2 diabetes underwent a euglycemic hyperinsulinemic clamp to measure insulin sensitivity. Genetic predisposition for Type 2 diabetes, but not for overweight/obesity, was associated with inappropriate expansion of the adipose cells, reduced insulin sensitivity and a more proatherogenic lipid profile in non-obese individuals. However, obesity per se induced a similar expansion of adipose cells and dysmetabolic state irrespective of genetic predisposition.

Conclusions/Significance

Genetic predisposition for Type 2 diabetes, but not obesity, is associated with an impaired ability to recruit new adipose cells to store excess lipids in the subcutaneous adipose tissue, thereby promoting ectopic lipid deposition. This becomes particularly evident in non-obese individuals since obesity per se promotes a dysmetabolic state irrespective of genetic predisposition. These results identify a novel susceptibility factor making individuals with a genetic predisposition for Type 2 diabetes particularly sensitive to the environment and caloric excess.     

Decreased Circulating Levels of APRIL: Questioning Its Role in Diabetes

Diabetes mellitus is a chronic disease that affects over 382 million people worldwide. Type-1 Diabetes (T1D) is classified as an autoimmune disease that results from pancreatic β-cell destruction and insulin deficiency. Type-2 Diabetes (T2D) is characterized principally by insulin resistance in target tissues followed by decreased insulin production due to β-cell failure. It is challenging to identify immunological markers such as inflammatory molecules that are triggered in response to changes during the pathogenesis of diabetes. APRIL is an important member of the TNF family and has been linked to chronic inflammatory processes of various diseases since its discovery in 1998. Therefore, this study aimed to evaluate APRIL serum levels in T1D and T2D. For this, we used the ELISA assay to measure serum APRIL levels of 33 T1D and 30 T2D patients, and non-diabetic subjects as control group. Our data showed a decrease in serum APRIL levels in T1D patients when compared with healthy individuals. The same pattern was observed in the group of T2D patients when compared with the control. The decrease of serum APRIL levels in diabetic patients suggests that this cytokine has a role in T1D and T2D. Diabetes is already considered as an inflammatory condition with different cytokines being implicated in its physiopathology. Our data suggest that APRIL can be considered as a potential modulating cytokine in the inflammatory process of diabetes.