Contribution of adipocyte-derived factors to beta-cell dysfunction in diabetes

Metabolic Syndrome: A Narrative Review from the Oxidative Stress to the Management of Related Diseases

Metabolic syndrome (MS) is a growing disorder affecting thousands of people worldwide, especially in industrialised countries, increasing mortality. Oxidative stress, hyperglycaemia, insulin resistance, inflammation, dysbiosis, abdominal obesity, atherogenic dyslipidaemia and hypertension are important factors linked to MS clusters of different pathologies, such as diabesity, cardiovascular diseases and neurological disorders. All biochemical changes observed in MS, such as dysregulation in the glucose and lipid metabolism, immune response, endothelial cell function and intestinal microbiota, promote pathological bridges between metabolic syndrome, diabesity and cardiovascular and neurodegenerative disorders. This review aims to summarise metabolic syndrome's involvement in diabesity and highlight the link between MS and cardiovascular and neurological diseases. A better understanding of MS could promote a novel strategic approach to reduce MS comorbidities.

Influence of hsCRP Parameter on the Occurrence of Metabolic Syndrome in Patients with Polycystic Ovary Syndrome

PCOS (polycystic ovary syndrome) is a common endocrine disorder that affects 8-13% of women of reproductive age. Increased body weight and insulin resistance may be associated with chronic inflammation, which increases the risk of cardiovascular complications. CRP (C-reactive protein) tests may be use to assess persistent inflammation. Elevated CRP levels may be associated with insulin resistance and type 2 diabetes. Determination of hsCRP, highly sensitive C-reactive protein, can be used to assess cardiovascular risk in women with PCOS. In this study, 120 women between the ages of 18 and 42 were divided into two groups: patients with polycystic ovary syndrome (n = 80) and regular menstruating women in whom PCOS was excluded (n = 40). Lipid and carbohydrate metabolism parameters and hsCRP levels were assessed, followed by receiver operating characteristic (ROC) analysis for hsCRP, where metabolic syndrome was the dependent variable. For hsCRP, the cutoff point was 1.44 (mg/dL). Sensitivity for the cutoff point was 0.913 and specificity was 0.691. The area under the curve (AUC) was 0.851 (p < 0.000). The closer the AUC value is to unity, the better the predictive ability of the studied variable. There was also a statistically significant correlation between hsCRP levels and the presence of metabolic syndrome.

Role of obesity related inflammation in pathogenesis of peripheral artery disease in patients of type 2 diabetes mellitus

Objective

Type 2 diabetes mellitus (T2DM) has emerged as one of the greatest global health challenges of twenty-first century. Visceral obesity is one of the most important determinant of insulin resistance (IR) as well as T2DM complications. Therefore this review focuses on the molecular mechanism of obesity induced inflammation, signaling pathways contributing to diabetes, as well as role of lifestyle interventions and medical therapies in the prevention and management of T2DM.

Method

Articles were searched on digital data base PubMed, Cochrane Library, and Web of Science. The key words used for search included Type 2 diabetes mellitus, obesity, insulin resistance, vascular inflammation and peripheral arterial disease.

Result

Visceral obesity is associated with chronic low grade inflammation and activation of immune systems which are involved in pathogenesis of obesity related IR and T2DM.

Conclusion

Metabolic dysregulation of adipose tissue leads to local hypoxia, misfolded/unfolded protein response and increased circulating free fatty acids, which in turn initiate inflammatory signaling cascades in the population of infiltrating cells. Mechanism that relates the role of adipocytokines with insulin sensitivity and glucose homeostasis might throw a light on the development of therapeutic interventions and subsequently might result in the reduction of vascular complications.

Pancreatic fat in type 2 diabetes: Causal or coincidental?

Type 2 diabetes (T2D) is a multifactorial metabolic disorder affecting more than 450 million people across the globe. With the increasing prevalence of T2D and obesity, the role of fat accumulation at sites other than subcutaneous adipose tissue has received significant attention in the pathophysiology of T2D. Over the past decade and a half, a pressing concern has emerged on investigating the association of pancreatic fat accumulation or pancreatic steatosis with the development of disease. While a few reports have suggested a possible association between pancreatic fat and T2D and/or impaired glucose metabolism, a few reports suggest a lack of such association. Pancreatic fat has also been linked with genetic risk of developing T2D, prediabetes, reduced insulin secretion, and beta cell dysfunction albeit some confounding factors such as age and ethnicity may affect the outcome. With the technological advancements in clinical imaging and progress in assessment of pancreatic beta cell function, our understanding of the role of pancreatic fat in causing insulin resistance and development of various etiologies of T2D has significantly improved. This review summarizes various findings on the possible association of pancreatic fat accumulation with the pathophysiology of T2D.

Adipose Tissue Secretion Pattern Influences β-Cell Wellness in the Transition from Obesity to Type 2 Diabetes

The dysregulation of the β-cell functional mass, which is a reduction in the number of β-cells and their ability to secure adequate insulin secretion, represents a key mechanistic factor leading to the onset of type 2 diabetes (T2D). Obesity is recognised as a leading cause of β-cell loss and dysfunction and a risk factor for T2D. The natural history of β-cell failure in obesity-induced T2D can be divided into three steps: (1) β-cell compensatory hyperplasia and insulin hypersecretion, (2) insulin secretory dysfunction, and (3) loss of β-cell mass. Adipose tissue (AT) secretes many hormones/cytokines (adipokines) and fatty acids that can directly influence β-cell function and viability. As this secretory pattern is altered in obese and diabetic patients, it is expected that the cross-talk between AT and pancreatic β-cells could drive the maintenance of the β-cell integrity under physiological conditions and contribute to the reduction in the β-cell functional mass in a dysmetabolic state. In the current review, we summarise the evidence of the ability of the AT secretome to influence each step of β-cell failure, and attempt to draw a timeline of the alterations in the adipokine secretion pattern in the transition from obesity to T2D that reflects the progressive deterioration of the β-cell functional mass.

Free fatty acid receptors in the endocrine regulation of glucose metabolism: Insight from gastrointestinal-pancreatic-adipose interactions

Glucose metabolism is primarily controlled by pancreatic hormones, with the coordinated assistance of the hormones from gastrointestine and adipose tissue. Studies have unfolded a sophisticated hormonal gastrointestinal-pancreatic-adipose interaction network, which essentially maintains glucose homeostasis in response to the changes in substrates and nutrients. Free fatty acids (FFAs) are the important substrates that are involved in glucose metabolism. FFAs are able to activate the G-protein coupled membrane receptors including GPR40, GPR120, GPR41 and GPR43, which are specifically expressed in pancreatic islet cells, enteroendocrine cells as well as adipocytes. The activation of FFA receptors regulates the secretion of hormones from pancreas, gastrointestine and adipose tissue to influence glucose metabolism. This review presents the effects of the FFA receptors on glucose metabolism via the hormonal gastrointestinal-pancreatic-adipose interactions and the underlying intracellular mechanisms. Furthermore, the development of therapeutic drugs targeting FFA receptors for the treatment of abnormal glucose metabolism such as type 2 diabetes mellitus is summarized.

Pancreatic fat cells of humans with type 2 diabetes display reduced adipogenic and lipolytic activity

Obesity, especially visceral fat accumulation, increases the risk of type 2 diabetes (T2D). The purpose of this study was to investigate the impact of T2D on the pancreatic fat depot. Pancreatic fat pads from 17 partial pancreatectomized patients (PPP) were collected, pancreatic preadipocytes isolated, and in vitro differentiated. Patients were grouped using HbA1c into normal glucose tolerant (NGT), prediabetic (PD), and T2D. Transcriptome profiles of preadipocytes and adipocytes were assessed by RNAseq. Insulin sensitivity was estimated by quantifying AKT phosphorylation on Western blots. Lipogenic capacity was assessed with oil red O staining, lipolytic activity via fatty acid release. Secreted factors were measured using ELISA. Comparative transcriptome analysis of preadipocytes and adipocytes indicates defective upregulation of genes governing adipogenesis (NR1H3), lipogenesis (FASN, SCD, ELOVL6, and FADS1), and lipolysis (LIPE) during differentiation of cells from T2D-PPP. In addition, the ratio of leptin/adiponectin mRNA was higher in T2D than in NGT-PPP. Preadipocytes and adipocytes of NGT-PPP were more insulin sensitive than T2D-PPP cells in regard to AKT phosphorylation. Triglyceride accumulation was similar in NGT and T2D adipocytes. Despite a high expression of the receptors NPR1 and NPR2 in NGT and T2D adipocytes, lipolysis was stimulated by ANP 1.74-fold in NGT cells only. This stimulation was further increased by the PDE5 inhibitor dipyridamole (3.09-fold). Dipyridamole and forskolin increased lipolysis receptor independently 1.88-fold and 1.48-fold, respectively, solely in NGT cells. In conclusion, the metabolic status persistently affects differentiation and lipolysis of pancreatic adipocytes. These alterations could aggravate the development of T2D.

Leonotis Leonurus improves the crosstalk between peripheral tissues both in vivo and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Unravelling the anti-diabetic mechanism of action of L. leonurus at adipose, liver, muscle and pancreatic level.

AIMS

To investigate the mechanism of action of an organic extract of L. leonurus and marrubiin at the gene level in adipose, liver and muscle tissues of an obese rat model and in a co-culture model.

MATERIALS AND METHODS

Obese Wistar rats were fed a cafeteria diet for eight weeks, treated with an extract of L. Leonurus, marrubiin, sulfonylurea and aspirin for two weeks and the level of gene expression of selected markers were investigated across different tissues. The effects mediated by the different treatments were investigated in co-culture cell models involving 3T3-L1 (fat), Chang (liver), C2C12 (muscle) and INS-1 (pancreatic) cells under both normal and hyperglycemic conditions.

RESULTS

L. leonurus extract mediated a significant increase in PPAR gamma, glucokinase, FAS and UCP2 gene expression in adipose tissue, whilst the opposite was observed in the liver. At the muscle level, a significant increase in FAS gene expression was observed relative to the obese control rats. Furthermore, the extract as well as marrubiin, modulated improvements in the adipokine profile. The co-culture models showed that the effect mediated by the extract was dependent on, the tissue type as well as the glycemic conditions.

CONCLUSIONS

L. Leonurus extract as well as marrubiin exhibit anti-diabetic properties where the mechanism of action is mainly at the adipose tissue level. The increase in expression of the genes of interest mentioned above potentially play a protective role towards the liver and possibly towards the muscle tissues as well.

Reprint of: Recent Updates on Obesity Treatments: Available Drugs and Future Directions

In the last thirty years, obesity has reached epidemic proportions and is now regarded as a major health issue in contemporary society trending to serious economic and social burdens. The latest projections of the World Health Organization are alarming. By 2030, nearly 60% of the worldwide population could be either obese or overweight, highlighting the needs to find innovative treatments. Currently, bariatric surgery is the most effective way to efficiently lower body mass. Although great improvements in terms of recovery and patient care were made in these surgical procedures, bariatric surgery remains an option for extreme forms of obesity and seems unable to tackle obesity pandemic expansion. Throughout the last century, numerous pharmacological strategies targeting either peripheral or central components of the energy balance regulatory system were designed to reduce body mass, some of them reaching sufficient levels of efficiency and safety. Nevertheless, obesity drug therapy remains quite limited on its effectiveness to actually overcome the obesogenic environment. Thus, innovative unimolecular polypharmacology strategies, able to simultaneously target multiple actors involved in the obesity initiation and expansion, were developed during the last ten years opening a new promising avenue in the pharmacological management of obesity. In this review, we first describe the clinical features of obesity-associated conditions and then focus on the outcomes of currently approved drug therapies for obesity as well as new ones expecting to reach the clinic in the near future.

Recent Updates on Obesity Treatments: Available Drugs and Future Directions

In the last thirty years, obesity has reached epidemic proportions and is now regarded as a major health issue in contemporary society trending to serious economic and social burdens. The latest projections of the World Health Organization are alarming. By 2030, nearly 60% of the worldwide population could be either obese or overweight, highlighting the needs to find innovative treatments. Currently, bariatric surgery is the most effective way to efficiently lower body mass. Although great improvements in terms of recovery and patient care were made in these surgical procedures, bariatric surgery remains an option for extreme forms of obesity and seems unable to tackle obesity pandemic expansion. Throughout the last century, numerous pharmacological strategies targeting either peripheral or central components of the energy balance regulatory system were designed to reduce body mass, some of them reaching sufficient levels of efficiency and safety. Nevertheless, obesity drug therapy remains quite limited on its effectiveness to actually overcome the obesogenic environment. Thus, innovative unimolecular polypharmacology strategies, able to simultaneously target multiple actors involved in the obesity initiation and expansion, were developed during the last ten years opening a new promising avenue in the pharmacological management of obesity. In this review, we first describe the clinical features of obesity-associated conditions and then focus on the outcomes of currently approved drug therapies for obesity as well as new ones expecting to reach the clinic in the near future.

Modulation of P2Y11-related purinergic signaling in inflammation and cardio-metabolic diseases

Chronic inflammation is the hallmark of cardiovascular pathologies with a major role in both disease progression and occurrence of long-term complications. The massive release of ATP during the inflammatory process activates various purinergic receptors, including P2Y11. This receptor is less studied but ubiquitously expressed in all cells relevant for cardiovascular pathology: cardiomyocytes, fibroblasts, endothelial and immune cells. While several studies suggested a potential pro-inflammatory role for P2Y11 receptors, recent literature data are supportive of an anti-inflammatory profile characterized by the immunosuppression of dendritic cells, inhibition of fibroblast proliferation and of cytokines and ATP secretion. Moreover, modulation of its activity appears to mediate the positive inotropic effect of ATP and mitigate endothelial dysfunction, thus rendering this receptor a promising therapeutic target in the cardiovascular disease armamentarium. The aim of the present review is to summarize the current available knowledge on P2Y11-related purinergic signaling in the setting of inflammation and cardio-metabolic diseases.

The Complex Interactions Between Obesity, Metabolism and the Brain

Obesity is increasing at unprecedented levels globally, and the overall impact of obesity on the various organ systems of the body is only beginning to be fully appreciated. Because of the myriad of direct and indirect effects of obesity causing dysfunction of multiple tissues and organs, it is likely that there will be heterogeneity in the presentation of obesity effects in any given population. Taken together, these realities make it increasingly difficult to understand the complex interplay between obesity effects on different organs, including the brain. The focus of this review is to provide a comprehensive view of metabolic disturbances present in obesity, their direct and indirect effects on the different organ systems of the body, and to discuss the interaction of these effects in the context of brain aging and the development of neurodegenerative diseases.

What role do fat cells play in pancreatic tissue?

Background

It is now generally accepted that obesity is a major risk factor for type 2 diabetes mellitus (T2DM). Hepatic steatosis in particular, as well as visceral and ectopic fat accumulation within tissues, is associated with the development of the disease. We recently presented the first study on isolated human pancreatic adipocytes and their interaction with islets [Gerst, F., Wagner, R., Kaiser, G., Panse, M., Heni, M., Machann, J., et al., 2017. Metabolic crosstalk between fatty pancreas and fatty liver: effects on local inflammation and insulin secretion. Diabetologia 60(11):2240–2251.]. The results indicate that the function of adipocytes depends on the overall metabolic status in humans which, in turn, differentially affects islet hormone release.

Scope of Review

This review summarizes former and recent studies on factors derived from adipocytes and their effects on insulin-secreting β-cells, with particular emphasis on the human pancreas. The adipocyte secretome is discussed with a special focus on its influence on insulin secretion, β-cell survival and apoptotic β-cell death.

Major Conclusions

Human pancreatic adipocytes store lipids and release adipokines, metabolites, and pro-inflammatory molecules in response to the overall metabolic, humoral, and neuronal status. The differentially regulated adipocyte secretome impacts on endocrine function, i.e., insulin secretion, β-cell survival and death which interferes with glycemic control. This review attempts to explain why the extent of pancreatic steatosis is associated with reduced insulin secretion in some studies but not in others.

l-Carnitine-induced amelioration of HFD-induced hepatic dysfunction is accompanied by a reduction in hepatic TNF-α and TGF-β1

In this study, we evaluated the possible mechanisms through which l-carnitine ameliorates the adverse effects from obesity in rats, induced with a high-fat diet (HFD). For this, 56 albino Wister rats were randomly assigned to 7 groups. The control group was fed a basal diet and injected with saline. The second group was fed the basal diet and injected with l-carnitine (200 mg/kg body mass, by intraperitoneal injection; i.p.). The third group were fed the HFD. The fourth group was fed the HFD and injected with l-carnitine (200 mg/kg body mass, i.p.) for 8 weeks. The fifth group was fed the HFD for 10 weeks. The sixth group were fed the HFD for 10 weeks and were also injected with l-carnitine (200 mg/kg body mass, i.p.) during the final 2 weeks. The seventh group was fed the HFD diet for 8 weeks then the basal diet for 2 weeks. The HFD induced significantly increased levels of hyperglycemia, lipid peroxidation, pathological changes, TNF-α and TGF-β1 protein expression in hepatic tissue, food intake, body weight gain, serum levels of total and non-high-density lipoprotein cholesterol, ketone bodies, triacylglycerol, urea, creatinine, AST, and ALT. However, the HFD diet significantly decreased serum levels of high-density lipoprotein (HDL) and hepatic levels of reduced glutathione. l-Carnitine ameliorated the effects of the HFD on the above-mentioned parameters. This study indicated that l-carnitine had protective and curative effects against HFD-induced hepatosteatosis by reducing hepatic oxidative stress and protein expression of TNF-α and TGF-β1.

Design, synthesis chalcone derivatives as AdipoR agonist for type 2 diabetes

Two structurally novel series of chalcone derivatives were designed and synthesized as potential agents against type 2 diabetes. As a result of the antidiabetic biological evaluation in streptozotocin (STZ)-induced type 2 diabetes animal model, 13e, 13g, and 19f showed more significant reduction in serum Glu, TG, TC levels by contrast to the positive control AdipoRon. In addition to upregulating the expression of AdipoR1 and AdipoR2, 13e and 19f treatment also increased expression of AMPK and PPAR-α. Taken together, these results suggested that 13e and 19f might be a promising compound for type 2 diabetes treatment.

Type 2 diabetes: Does pancreatic fat really matter?

With the increasing prevalence of obesity, the interest of research in nonalcoholic fatty pancreas disease (NAFPD) has grown. Even though the pancreas appears more susceptible to lipid accumulation compared with the liver, NAFPD has been less investigated due to the limits in detecting techniques. Several definitions and synonyms for NAFPD are used by authors and can be misleading. This, together with differences in methodology and ethnicity, make the integration and comparison of studies on this topic challenging. NAFPD could be used as an early indicator of ectopic fat deposition, which is recognized as a key factor of obesity cardio-metabolic complications. However, evidence that NAFPD has a pathogenetic role in type 2 diabetes is also emerging. This article reviews the current state of knowledge on the clinical and pathophysiologic relevance of NAFPD in β-cell function and insulin resistance.

Effects of progressive resistance training and weight loss versus weight loss alone on inflammatory and endothelial biomarkers in older adults with type 2 diabetes

PURPOSE

Type 2 diabetes has been associated with an increase in inflammatory and endothelial biomarkers, which are associated with an increased risk of cardiovascular disease and diabetes-related complications. This study examined the effects of high-intensity progressive resistance training (PRT) with moderate weight loss (WL) versus WL alone on inflammatory and endothelial biomarkers in older overweight adults with type 2 diabetes.

METHODS

This was a 12-month randomized controlled trial in which 36 inactive, overweight adults aged 60-80 years with poorly controlled type 2 diabetes were randomized to 6 months of supervised PRT + WL or stretching (sham) exercise plus WL followed by 6 months of home-training without dietary modification. Fasted blood samples were collected at baseline and subsequent 3-month intervals with the following inflammatory [interleukin (IL)-10, IL-6, tumor necrosis factor (TNF)-α, adiponectin] and endothelial markers [resistin and intercellular adhesion molecule (ICAM)-1)] assessed.

RESULTS

No significant within-group changes or between-group differences were detected for any inflammatory or endothelial biomarker following the 6-month supervised exercise and WL phase. There was a greater reduction in IL-10 at 9 months in the PRT + WL relative to WL group (P = 0.033). There was also a greater reduction in TNF-α at 9 and 12 months in the PRT + WL relative to WL group (P = 0.026 and P = 0.024, respectively). Serum adiponectin increased in the PRT + WL relative to WL group after 12 months (P = 0.036). All results were adjusted for baseline values, age, weight, sex, diabetes duration, medication use and any change in medication.

CONCLUSIONS

Long-term participation in PRT, independent of change in weight, can result in some improvements in certain inflammatory markers in older overweight adults with type 2 diabetes.

The association of serum leptin levels with metabolic diseases

Leptin is a 167-amino-acid protein released by white adipose tissue and encoded by the obese gene. It has a role as a negative regulator of appetite control through sending a satiety signal to act on receptors within the hypothalamus. At normal levels, leptin can exert its effects on weight regulation according to white fat mass, induce sodium excretion, maintain vascular tone, and repair the myocardium. Beyond these effects, elevated serum leptin levels have been implicated in the pathogenesis of metabolic syndrome, diabetes mellitus, hypertension, and multiple cardiovascular diseases. In addition, hyperleptinemia had been reported to contribute to renal diseases through multiple mechanisms resulting in glomerulopathy presenting with a decreased glomerular filtration rate, increased albuminuria, and related clinical symptoms, which are pathophysiological features of chronic kidney disease. Because these cardiovascular and metabolic disorders are great challenges for physicians, understanding the related pathophysiological association with leptin might become a valuable aid in handling patients in daily clinical practice. This review will discuss the roles of leptin in the regulation of biological functions of multiple organs beyond the maintenance of feeding and metabolism.

Obesity, Oxidative Stress, Adipose Tissue Dysfunction, and the Associated Health Risks: Causes and Therapeutic Strategies

Obesity is gaining acceptance as a serious primary health burden that impairs the quality of life because of its associated complications, including diabetes, cardiovascular diseases, cancer, asthma, sleep disorders, hepatic dysfunction, renal dysfunction, and infertility. It is a complex metabolic disorder with a multifactorial origin. Growing evidence suggests that oxidative stress plays a role as the critical factor linking obesity with its associated complications. Obesity per se can induce systemic oxidative stress through various biochemical mechanisms, such as superoxide generation from NADPH oxidases, oxidative phosphorylation, glyceraldehyde auto-oxidation, protein kinase C activation, and polyol and hexosamine pathways. Other factors that also contribute to oxidative stress in obesity include hyperleptinemia, low antioxidant defense, chronic inflammation, and postprandial reactive oxygen species generation. In addition, recent studies suggest that adipose tissue plays a critical role in regulating the pathophysiological mechanisms of obesity and its related co-morbidities. To establish an adequate platform for the prevention of obesity and its associated health risks, understanding the factors that contribute to the cause of obesity is necessary. The most current list of obesity determinants includes genetic factors, dietary intake, physical activity, environmental and socioeconomic factors, eating disorders, and societal influences. On the basis of the currently identified predominant determinants of obesity, a broad range of strategies have been recommended to reduce the prevalence of obesity, such as regular physical activity, ad libitum food intake limiting to certain micronutrients, increased dietary intake of fruits and vegetables, and meal replacements. This review aims to highlight recent findings regarding the role of oxidative stress in the pathogenesis of obesity and its associated risk factors, the role of dysfunctional adipose tissue in development of these risk factors, and potential strategies to regulate body weight loss/gain for better health benefits.

Diluted serum from calorie-restricted animals promotes mitochondrial β-cell adaptations and protect against glucolipotoxicity

β-cells quickly adjust insulin secretion to oscillations in nutrients carried by the blood, acting as fuel sensors. However, most studies of β-cell responses to nutrients do not discriminate between fuel levels and signaling components present in the circulation. Here we studied the effect of serum from calorie-restricted rats versus serum from rats fed ad libitum, diluted tenfold in the medium, which did not contribute significantly to the pool of nutrients, on β-cell mitochondrial function and dynamics under regular and high-nutrient culture conditions. Insulin secreting beta-cell derived line (INS1) cells incubated with serum from calorie-restricted rats (CR serum) showed higher levels of peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC-1α) and active nitric oxide synthase. The expression of mitofusin-2 (Mfn-2) and optic atrophy 1 (OPA-1), proteins involved in mitochondrial fusion, was increased, while the levels of the mitochondrial fission mediator dynamin related protein 1 (DRP-1) were reduced. Consistent with changes in mitochondrial dynamics protein levels, CR serum treatment increased mitochondrial fusion rates, as well as their length and connectivity. These changes in mitochondrial morphology were associated with prolonged glucose-stimulated insulin secretion and mitochondrial respiration. When combining CR serum and high levels of glucose and palmitate (20 and 0.4 mm, respectively), an in vitro model of type II diabetes, we observed that signaling promoted by CR serum was enough to overcome glucolipotoxicity, as indicated by CR-mediated prevention of mitochondrial fusion arrest and reduced respiratory function in INS1 cells under glucolipotoxicity. Overall, our results provide evidence that non-nutrient factors in serum have a major impact on β-cell mitochondrial adaptations to changes in metabolism.

Beneficial role of vitamin K supplementation on insulin sensitivity, glucose metabolism, and the reduced risk of type 2 diabetes: A review

Micronutrients are gaining acceptance as an important nutritional therapy for the prevention and/or management of diabetes and its associated health risks. Although a very small quantity of micronutrients are required for specific functions in our bodies, moderate deficiencies can lead to serious health issues. Impaired insulin sensitivity and glucose intolerance play a major role in the development of diabetic pathophysiology. Vitamin K is well known for its function in blood coagulation. Moreover, several human studies reported the beneficial role of vitamin K supplementation in improving insulin sensitivity and glucose tolerance, preventing insulin resistance, and reducing the risk of type 2 diabetes (T2 D). Both animal and human studies have suggested that vitamin K-dependent protein (osteocalcin [OC]), regulation of adipokine levels, antiinflammatory properties, and lipid-lowering effects may mediate the beneficial function of vitamin K in insulin sensitivity and glucose tolerance. This review for the first time provides an overview of the currently available preclinical and clinical evidences on the effect of vitamin K supplementation in the management of insulin sensitivity and glucose tolerance. The outcome of this review will increase understanding for the development of a novel adjuvant therapy to achieve better control of glycemia and improve the lives of diabetic patients.

Associations of the Inflammatory Marker YKL-40 with Measures of Obesity and Dyslipidaemia in Individuals at High Risk of Type 2 Diabetes

Introduction

Circulating levels of the inflammatory marker YKL-40 are elevated in cardiovascular disease and obesity-related type 2 diabetes (T2D), and serum YKL-40 levels are related to elements of dyslipidaemia.

Objective

We aimed to investigate the associations between serum YKL-40 and obesity-related traits in a Danish sample of non-diabetic relatives to T2D patients and, furthermore, to estimate the heritability of YKL-40.

Research Design and Methods

324 non-diabetic individuals with family relation to a T2D patient were included in the study. The participants underwent oral- and intravenous glucose tolerance tests for estimation of glucose tolerance and surrogate measures of insulin sensitivity. Anthropometric measures were retrieved and biochemical measures of the plasma lipid profile and serum YKL-40 levels were obtained. Association-analyses between serum YKL-40 and obesity-related traits and estimates of the narrow sense heritability of YKL-40 were based on a polygenic variance component model.

Results

Fasting serum levels of YKL-40 were positively associated with waist-hip-ratio (p<0.001) and fasting plasma triglyceride levels (p<0.001). None of the insulin sensitivity indexes were significantly associated with YKL-40. According to the AE model, the familiality-estimate h² of YKL-40 was 0.45 (SE 0.13). When the ACE-model was applied, the heritability-estimate h² of YKL-40 did not reach statistical significance.

Conclusions

Our results suggest a role of serum YKL-40 in obesity-related low grade inflammation, but do not indicate that YKL-40 is directly involved in the development of T2D.

Visceral adiposity index: an indicator of adipose tissue dysfunction

The Visceral Adiposity Index (VAI) has recently proven to be an indicator of adipose distribution and function that indirectly expresses cardiometabolic risk. In addition, VAI has been proposed as a useful tool for early detection of a condition of cardiometabolic risk before it develops into an overt metabolic syndrome. The application of the VAI in particular populations of patients (women with polycystic ovary syndrome, patients with acromegaly, patients with NAFLD/NASH, patients with HCV hepatitis, patients with type 2 diabetes, and general population) has produced interesting results, which have led to the hypothesis that the VAI could be considered a marker of adipose tissue dysfunction. Unfortunately, in some cases, on the same patient population, there is conflicting evidence. We think that this could be mainly due to a lack of knowledge of the application limits of the index, on the part of various authors, and to having applied the VAI in non-Caucasian populations. Future prospective studies could certainly better define the possible usefulness of the VAI as a predictor of cardiometabolic risk.

A synergistic therapeutic scheme for hyperglycemia and nephrotic disorders in diabetes

We previously demonstrated that the utilization of an electrospun scaffold could boost functional outputs of transplanted islets. In this study, we aim to develop a drug-eluting scaffold with a payload of pioglitazone to simultaneously rein in hyperglycemia and recoup lost renal functions in diabetic mice that underwent islet transplantation. The in vivo proliferation of islets was measured by a non-invasive bio-imaging technology whereas the blood insulin, blood glucose and renal proteins were assayed. The local stimulation of transplanted islets by pioglitazone saw an accelerated in vivo proliferation without apoptosis caused by the drug-eluting scaffold. In addition, pioglitazone contributed to an increased secretion of insulin and C-peptide 2, giving rise to an accelerated rein-in of hyperglycemia and enhanced tolerance of sudden oral glucose challenge. Moreover, the accelerated decrease of blood creatinine, urine creatinine and blood urea nitrogen suggested that pioglitazone contributed to the recovery of renal functions compromised by diabetes. Our bioengineering strategy effectively ameliorated hyperglycemia and associated nephrotic disorders, and shed a new light on an engineering approach to combat diabetes.

The acute effects of low-dose TNF-α on glucose metabolism and β-cell function in humans

Type 2 diabetes is characterized by increased insulin resistance and impaired insulin secretion. Type 2 diabetes is also associated with low-grade inflammation and increased levels of proinflammatory cytokines such as TNF-α. TNF-α has been shown to impair peripheral insulin signaling in vitro and in vivo. However, it is unclear whether TNF-α may also affect endogenous glucose production (EGP) during fasting and glucose-stimulated insulin secretion (GSIS) in vivo. We hypothesized that low-dose TNF-α would increase EGP and attenuate GSIS. Recombinant human TNF-α or placebo was infused in healthy, nondiabetic young men (n = 10) during a 4-hour basal period followed by an intravenous glucose tolerance test (IVGTT). TNF-α lowered insulin levels by 12% during the basal period (P < 0.05). In response to the IVGTT, insulin levels increased markedly in both trials, but there was no difference between trials. Compared to placebo, TNF-α did not affect EGP during the basal period. Our results indicate that TNF-α acutely lowers basal plasma insulin levels but does not impair GSIS. The mechanisms behind this are unknown but we suggest that it may be due to TNF-α increasing clearance of insulin from plasma without impairing beta-cell function or hepatic insulin sensitivity.

Insulin secretion and its association with physical activity, fitness and screen time in children

OBJECTIVES

To determine the independent associations of moderate to vigorous physical activity (MVPA), fitness, screen time, and adiposity with insulin secretion in children.

DESIGN AND METHODS

Caucasian youth (n = 423/630), 8-10 years old, with at least one obese biological parent, were studied (QUALITY cohort). Insulin secretion was measured using HOMA2-%B, area under the curve (AUC) of insulin to glucose over the first 30 minutes (AUC I/G(t30min)) of the OGTT and AUC I/G(t120min) over 2 hours. Fitness was measured by VO₂peak ; percent fat mass (PFM) by DXA; 7-day MVPA by accelerometry; self-reported screen time included television, video game, or computer use. Models were adjusted for age, sex, season, puberty, PFM, and insulin sensitivity [IS] (HOMA2-IS, Matsuda-ISI).

RESULTS

PFM was strongly associated with insulin secretion, even after adjustment for IS: for every 1% increase in PFM, insulin secretion increased from 0.3% to 0.8% across indices. MVPA was negatively associated with HOMA2-%B (P < 0.05), but not with OGTT-derived measures. Fitness was negatively associated with AUC I/G(t120min) (P < 0.05). Screen time showed a trend toward higher HOMA2-%B in girls (P = 0.060).

CONCLUSIONS

In children with an obese parent, lower insulin secretion is associated with lower adiposity, higher MVPA, better fitness, and possibly reduced screen time.

Prevalence of metabolic syndrome in Behçet disease: a case-control study in Turkey

BACKGROUND

Chronic inflammatory diseases such as psoriasis, rheumatoid arthritis, and inflammatory bowel diseases have been reported to be associated with the development of metabolic syndrome (MetS), which is characterized by central obesity, elevated triglycerides (TG), reduced high-density lipoproteins (HDL), impaired fasting blood glucose (FBG), and hypertension. Behçet disease (BD) is a chronic, immuno-inflammatory disease with multisystemic involvement.

OBJECTIVE

The aim of this study was to investigate the prevalence and risk factors for MetS in patients with BD.

METHODS

All patients had BD according to the criteria of the International Study Group. Diagnosis of MetS was established according to National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria. Mean waist circumference, body mass index (BMI), FBG, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), total cholesterol, HDL, very low-density lipoprotein (VLDL), low-density lipoprotein (LDL), TG, systolic BP, and diastolic BP were measured and analyzed.

RESULTS

A total of 86 patients and 72 healthy controls were included. MetS was detected in 35.4 % of patients and 20 % of controls (p = 0.04). Patients with BD had a 2.67-fold higher risk for MetS than healthy controls (p < 0.05). Significant risk factors for developing MetS according to multivariate analyses were BD, age, and BMI. Age at onset of the disease, duration of disease, BMI, gastrointestinal system involvement, and neurological involvement were correlated with increased MetS risk (p < 0.05). MetS tended to increase with age and the duration of the disease and was higher in women under the age of 40 years compared with healthy controls in the same age group.

CONCLUSION

All BD patients should be closely monitored for hypertension, hyperlipidemia, and diabetes mellitus to avoid MetS development.

Role of inflammatory mechanisms in pathogenesis of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is characterized by progressive β-cell dysfunctioning and insulin resistance. This article reviews recent literature with special focus on inflammatory mechanisms that provoke the pathogenesis of T2DM. We have focused on the recent advances in progression of T2DM including various inflammatory mechanisms that might induce inflammation, insulin resistance, decrease insulin secretion from pancreatic islets and dysfunctioning of β-cells. Here we have also summarized the role of various pro-inflammatory mediators involved in inflammatory mechanisms, which may further alter the normal structure of β-cells by inducing pancreatic islet's apoptosis. In conclusion, it is suggested that the role of inflammation in pathogenesis of T2DM is crucial and cannot be neglected. Moreover, the insight of inflammatory responses in T2DM may provide a new gateway for the better treatment of diabetes mellitus.

Enhancing pancreatic Beta-cell regeneration in vivo with pioglitazone and alogliptin

Aims/Hypothesis

Pancreatic beta-cells retain limited ability to regenerate and proliferate after various physiologic triggers. Identifying therapies that are able to enhance beta-cell regeneration may therefore be useful for the treatment of both type 1 and type 2 diabetes.

Methods

In this study we investigated endogenous and transplanted beta-cell regeneration by serially quantifying changes in bioluminescence from beta-cells from transgenic mice expressing firefly luciferase under the control of the mouse insulin I promoter. We tested the ability of pioglitazone and alogliptin, two drugs developed for the treatment of type 2 diabetes, to enhance beta-cell regeneration, and also defined the effect of the immunosuppression with rapamycin and tacrolimus on transplanted islet beta mass.

Results

Pioglitazone is a stimulator of nuclear receptor peroxisome proliferator-activated receptor gamma while alogliptin is a selective dipeptidyl peptidase IV inhibitor. Pioglitazone alone, or in combination with alogliptin, enhanced endogenous beta-cell regeneration in streptozotocin-treated mice, while alogliptin alone had modest effects. In a model of syngeneic islet transplantation, immunosuppression with rapamycin and tacrolimus induced an early loss of beta-cell mass, while treatment with insulin implants to maintain normoglycemia and pioglitazone plus alogliptin was able to partially promote beta-cell mass recovery.

Conclusions/Interpretation

These data highlight the utility of bioluminescence for serially quantifying functional beta-cell mass in living mice. They also demonstrate the ability of pioglitazone, used either alone or in combination with alogliptin, to enhance regeneration of endogenous islet beta-cells as well as transplanted islets into recipients treated with rapamycin and tacrolimus.

Role of adipocytokines and its correlation with endocrine pancreatic function in patients with pancreatic cancer

INTRODUCTION

Some authors suggest that adipocytokines contribute to the induction of pancreatic carcinogenesis as well as the development of endocrine insufficiency.

AIMS

We evaluate the circulating concentrations of leptin, resistin and visfatin in patients with newly diagnosed pancreatic cancer (PC) and relationship between serum adipocytokines level and clinicopathological features of PC. Moreover the usefulness of those adipocytokines as possible biomarkers of endocrine pancreatic function in PC has been assessed.

METHODS

The pilot study group consisted of 45 individuals (mean age 65.6 ± 11.5 years, BMI 21.8 ± 3.4 kg/m(2)) with newly diagnosed PC (within last 1-3 months) and 13 healthy individuals with age, gender and BMI matched to the study group. Among PC patients 18 (40%) had recently diagnosed diabetes. Fasting plasma leptin, resistin, visfatin concentrations were determined with ELISA (R&D Systems, Phoenix Pharmaceuticals) and insulin by RIA (DakoCytomation).

RESULTS

Patients with PC as compared to controls had significantly lower plasma leptin (40.6 ± 21.3 vs 63.2 ± 16.3 pg/mL; p < 0,0008). In contrast PC patients showed more than six fold higher level of resistin (126.2 ± 143.2 vs 18.9 ± 7.2 ng/mL; p < 0.009) than controls. The median plasma visfatin was 2.8 ± 1.8 ng/mL, which was not significantly different from the controls (3.8 ± 1.1 ng/mL). When PC patients with and without diabetes were considered separately, plasma leptin concentrations among nondiabetic patients were slightly, but not significantly higher (44.6 ± 21.0) as compared to diabetics (34.5 ± 20.7). Moreover there was no difference between visfatin and resistin level in PC, among patients with and without diabetes. No significant differences between serum level of leptin, visfatin and resistin and age, gender, BMI, smoking status, tumor localization, distant metastases and pain has been found.

CONCLUSION

The results of this study confirm previous findings that patients with newly diagnosed pancreatic cancer are characterized with lower level of leptin. This pilot study showed significantly higher resistin concentrations in patients with PC in comparison to healthy controls, which may be helpful in PC early diagnosis. Changes in leptin and resistin level in PC are not likely related to endocrine disorders.

Psoriasis and metabolic syndrome: a systematic review and meta-analysis of observational studies

BACKGROUND

Increasing population-based studies have suggested a relationship between psoriasis and metabolic syndrome.

OBJECTIVE

The objective of this study was to perform a systematic review and meta-analysis that synthesizes the epidemiologic associations between psoriasis and metabolic syndrome.

METHODS

We searched for observational studies from MEDLINE, EMBASE, and Cochrane Central Register from Jan 1, 1980 to Jan 1, 2012. We applied the Meta-Analysis of Observational Studies in Epidemiology (MOOSE) guidelines in the conduct of this study.

RESULTS

We identified 12 observational studies with a total of 1.4 million study participants fulfilling the inclusion criteria, among whom 41,853 were patients with psoriasis. Based on random-effects modeling of cross-sectional and case-controlled studies, the pooled odds ratio (OR) for metabolic syndrome among patients with psoriasis was 2.26 (95% confidence interval [CI] 1.70-3.01) compared with the general population. Visual inspection of a funnel plot and formal analysis with the Egger test suggested publication bias and absence of small studies in the published literature (P = .03). A dose-response relationship was also observed between psoriasis severity and prevalence of metabolic syndrome.

LIMITATIONS

No studies to date have assessed incidence of metabolic syndrome among patients with psoriasis.

CONCLUSIONS

Compared with the general population, psoriasis patients have higher prevalence of metabolic syndrome, and patients with more severe psoriasis have greater odds of metabolic syndrome than those with milder psoriasis.

The role of adipokines in β-cell failure of type 2 diabetes

β-Cell failure coupled with insulin resistance is a key factor in the development of type 2 diabetes. Changes in circulating levels of adipokines, factors released from adipose tissue, form a significant link between excessive adiposity in obesity and both aforementioned factors. In this review, we consider the published evidence for the role of individual adipokines on the function, proliferation, death and failure of β-cells, focusing on those reported to have the most significant effects (leptin, adiponectin, tumour necrosis factor α, resistin, visfatin, dipeptidyl peptidase IV and apelin). It is apparent that some adipokines have beneficial effects whereas others have detrimental properties; the overall contribution to β-cell failure of changed concentrations of adipokines in the blood of obese pre-diabetic subjects will be highly dependent on the balance between these effects and the interactions between the adipokines, which act on the β-cell via a number of intersecting intracellular signalling pathways. We emphasise the importance, and comparative dearth, of studies into the combined effects of adipokines on β-cells.

Polyphenol-Rich Fraction of Brown Alga Ecklonia cava Collected from Gijang, Korea, Reduces Obesity and Glucose Levels in High-Fat Diet-Induced Obese Mice

Ecklonia cava (E. cava) is a brown alga that has beneficial effects in models of type 1 and type 2 diabetes. However, the effects of E. cava extracts on diet-induced obesity and type 2 diabetes have not been specifically examined. We investigated the effects of E. cava on body weight, fat content, and hyperglycemia in high-fat diet- (HFD) induced obese mice and sought the mechanisms involved. C57BL/6 male mice were fed a HFD (60% fat) diet or normal chow. After 3 weeks, the HFD diet group was given extracts (200 mg/kg) of E. cava harvested from Jeju (CA) or Gijang (G-CA), Korea or PBS by oral intubation for 8 weeks. Body weights were measured weekly. Blood glucose and glucose tolerance were measured at 7 weeks, and fat pad content and mRNA expression of adipogenic genes and inflammatory cytokines were measured after 8 weeks of treatment. G-CA was effective in reducing body weight gain, body fat, and hyperglycemia and improving glucose tolerance as compared with PBS-HFD mice. The mRNA expression of adipogenic genes was increased, and mRNA expression of inflammatory cytokines and macrophage marker gene was decreased in G-CA-treated obese mice. We suggest that G-CA reduces obesity and glucose levels by anti-inflammatory actions and improvement of lipid metabolism.

Protective effect of α-lipoic acid on islet cells co-cultured with 3T3L1 adipocytes

Obesity and β-cell dysfunction due to oxidative stress impact the pathogenesis of type 2 diabetes mellitus. We co-cultured 3T3L1 adipocytes and islet cells in the presence or absence of the antioxidant α-lipoic acid (LA) and assayed the effects of the adipocytes and LA on the secretion of insulin by the islet cells and on the activities of factors involved in secretion and oxidative stress. At low glucose concentrations (2.8 mmol/l), the presence of adipocytes (co-culture) increased insulin secretion compared with islet cells cultured alone (control) and this increase was diminished by LA (co-culture plus LA). At high glucose concentrations (22 mmol/l), insulin secretion levels were similar for all islet groups, resulting in a restoration of the stimulation index in the presence of LA. The mRNA levels of the glucose-stimulated insulin secretion (GSIS) genes glucokinase, glucose transporter 2 and Kir6.2 were downregulated under co-culture and co-culture plus LA conditions. Protein and tyrosine phosphorylation levels of insulin receptor-β and insulin receptor substrate-1 were decreased under co-culture conditions and were restored by LA treatment. Cellular malondialdehyde levels increased in the co-cultured islets and this increase was blocked by LA. The mRNA levels of superoxide dismutase and catalase were reduced under co-culture conditions and these reductions were eliminated by the addition of LA. In conclusion, 3T3L1 adipocytes disturb insulin secretion and induce islet dysfunction. The effects may be mediated by multiple pathways, which include downregulation of GSIS gene expression, suppression of islet cell insulin signaling and the induction of oxidative stress. LA may protect islet cells via activation of islet cell insulin signaling and the mRNA expression of antioxidant enzymes.

Obestatin regulates adipocyte function and protects against diet-induced insulin resistance and inflammation

The metabolic actions of the ghrelin gene-derived peptide obestatin are still unclear. We investigated obestatin effects in vitro, on adipocyte function, and in vivo, on insulin resistance and inflammation in mice fed a high-fat diet (HFD). Obestatin effects on apoptosis, differentiation, lipolysis, and glucose uptake were determined in vitro in mouse 3T3-L1 and in human subcutaneous (hSC) and omental (hOM) adipocytes. In vivo, the influence of obestatin on glucose metabolism was assessed in mice fed an HFD for 8 wk. 3T3-L1, hSC, and hOM preadipocytes and adipocytes secreted obestatin and showed specific binding for the hormone. Obestatin prevented apoptosis in 3T3-L1 preadipocytes by increasing phosphoinositide 3-kinase (PI3K)/Akt and extracellular signal-regulated kinase (ERK)1/2 signaling. In both mice and human adipocytes, obestatin inhibited isoproterenol-induced lipolysis, promoted AMP-activated protein kinase phosphorylation, induced adiponectin, and reduced leptin secretion. Obestatin also enhanced glucose uptake in either the absence or presence of insulin, promoted GLUT4 translocation, and increased Akt phosphorylation and sirtuin 1 (SIRT1) protein expression. Inhibition of SIRT1 by small interfering RNA reduced obestatin-induced glucose uptake. In HFD-fed mice, obestatin reduced insulin resistance, increased insulin secretion from pancreatic islets, and reduced adipocyte apoptosis and inflammation in metabolic tissues. These results provide evidence of a novel role for obestatin in adipocyte function and glucose metabolism and suggest potential therapeutic perspectives in insulin resistance and metabolic dysfunctions.

Interleukin-1 receptor antagonist: a new therapy for type 2 diabetes mellitus

Various complex mechanisms and their multifactorial pathways decisively provoke low-grade local and systemic inflammation in β-cells of pancreatic islets and peripheral tissues to induce β-cells' dysfunction and apoptosis, insulin resistance, and ultimately, overt type 2 diabetes mellitus (T2DM). Conventional antidiabetic agents are being less popular, as they have some potential adverse effects. Currently, many anti-inflammatory therapeutic modalities are being investigated to abate the infuriating effects of inducers of T2DM and among them, interleukin-1 receptor antagonist (IL-1Ra) is the only one that has been approved by US Food and Drug Administration. We have compared IL-1Ra with other anti-inflammatory agents and conventional antidiabetic agents. Although, IL-1Ra has broad-spectrum anti-inflammatory activities, it also has some limitations due to its short half-life. To overcome the problem of short half-life of IL-1Ra, recently, we fused IL-1Ra in recombinant human serum albumin and expressed it in Pichia pastoris. Its bioactivity was also checked by IL-1-induced A375.S2 apoptotic cells. Furthermore, we have also formulated IL-1Ra with Pluronic F-127-based thermosensitive gel and investigated its in vitro characteristics to prolong its therapeutic effects. Further studies are required to investigate its therapeutic effects against diabetes and diabetes-associated complications.

Waist circumference and metabolic risk factors have separate and additive effects on the risk of future Type 2 diabetes in patients with vascular diseases. A cohort study

AIMS

To assess the effect of various measures of adiposity and of metabolic risk factors, both separately and in combination, on the risk of future Type 2 diabetes in patients with manifest vascular diseases.

METHODS

This was a prospective cohort study in 2924 patients (mean age 59 ± 12 years) with manifest atherosclerosis. Metabolic risk factors were defined according to National Cholesterol Education Program criteria for the metabolic syndrome. Incidence of Type 2 diabetes was assessed by questionnaire and subsequent verification.

RESULTS

During a median follow-up of 4.9 years (range 3.0-7.6 years) there were 178 cases (6.1%) of incident Type 2 diabetes. An increase with 1 sd waist circumference showed a strong association with incident Type 2 diabetes in both men (hazard ratio 2.45, 95% CI 1.97-3.04) and women (hazard ratio 1.77, 95% CI 1.38-2.26). Compared with patients with normal (i.e. below the National Cholesterol Education Program criteria for abdominal adiposity) waist circumference and < 3 metabolic risk factors, both patients with normal waist circumference and ≥ 3 metabolic risk factors and patients with high (i.e. above the National Cholesterol Education Program criteria for abdominal adiposity) waist circumference and < 3 metabolic risk factors had an increased risk of Type 2 diabetes (hazard ratio 2.44, 95% CI 1.37-4.36 and hazard ratio 3.61, 95% CI 2.23-5.85, respectively). Patients with both high waist circumference and ≥ 3 metabolic risk factors had the highest risk of developing Type 2 diabetes (hazard ratio 10.76, 95% CI 6.95-16.64).

CONCLUSIONS

In patients with manifest atherosclerosis, both presence of ≥ 3 metabolic risk factors and presence of a high waist circumference alone are associated with increased risk for developing Type 2 diabetes. The combined presence of ≥ 3 metabolic risk factors and high waist circumference, which is present in 15% of patients, is associated with a 10-fold increased risk of future Type 2 diabetes. To identify patients with manifest atherosclerosis at the highest risk of developing Type 2 diabetes, fat distribution in combination with metabolic risk factors should be considered.

The role of low-grade inflammation in the polycystic ovary syndrome

PCOS is not only the most frequent cause of oligomenorrhea in young women, but also a metabolic disorder characterized by insulin resistance, glucose intolerance, dyslipidemia, and obesity, especially the visceral phenotype. PCOS represents a broad spectrum of endocrine and metabolic alterations which change with age and with increasing adiposity. In fact, during adolescence and youth the predominant clinical manifestations of PCOS are menstrual abnormalities, hirsutism and acne, whereas in peri-menopausal and post-menopausal periods metabolic disorders and an increased risk for cardiovascular diseases prevail. The pathogenetic links between PCOS and metabolic or cardiovascular complications are still debated. However, recent evidence has been focused on a condition of low-grade chronic inflammation as a potential cause of the long-term consequence of the syndrome. In this review we describe the state of low-grade inflammation observed in PCOS. In addition, we hypothesize the potential mechanisms responsible for the generation of this inflammatory state and the role played by low-grade inflammation in linking hyperandrogenism and insulin resistance with the metabolic and cardiovascular long-term complications of the syndrome.

Functional interactions between pancreatic beta cells and (pre)adipocytes

Type 2 diabetes is causally related to obesity and characterized by dysfunctional pancreatic beta cells. It is so far unclear whether direct interactions exist between adipocytes and beta cells and possibly raise any pathogenic relevance. In this study, we examined whether 9-day co-cultured 3T3-F442A (pre)adipocytes and primary rat pancreatic beta cells exert an influence on each other's function. In the presence of beta cells, 3T3-F442A cells became lipid-storing cells expressing markers of differentiated adipocytes and releasing adiponectin. This effect was attributed to the medium insulin levels (around 0.1 μM) and was associated with an elevated glucose consumption by the 3T3-F442A cells. The subsequent decrease in medium glucose concentration reduced the rate of insulin release by beta cells cultured at 10 mM glucose, and thus suppressed their degranulation during culture. These changes in beta cell function did not occur at 20 mM glucose and were reversible upon removal of the 3T3-F422A cells. They could not be reproduced by 3T3-F422A-conditioned medium containing varying adiponectin concentrations. These data indicate that insulin secreted by beta cells is sufficient to induce differentiation of preadipocytes without addition of exogenous adipogenic factors. Over 9 days culture, (pre)adipocytes did not directly and irreversibly affect beta cell functions.

Beneficial effects of oligopeptides from marine salmon skin in a rat model of type 2 diabetes

OBJECTIVE

This study aimed at investigating whether treatment with oligopeptides from marine salmon skin (OMSS) could modulate type 2 diabetes mellitus (T2DM)-related hyperglycemia and β-cell apoptosis in rats induced by high fat diet and low doses of streptozotocin and its therapeutic mechanisms.

METHODS

Groups of T2DM rats were treated with OMSS or bovine serum albumin (3.0 g/kg/d) for 4 wk and their blood samples, together with those of normal control rats, were collected before and 4 wk after treatment. The levels of fasting blood glucose (FBG) and insulin, serum superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione (GSH), tumor necrosis factor-alpha (TNFα), and interferon-gamma (IFNγ) in rats were determined. The islet cell apoptosis and Fas/FasL expression were detected by TUNEL and immunohistochemistry.

RESULTS

In comparison with control rats, higher levels of FBG and frequency of apoptotic islet cells were detected in the bovine serum albumin group of diabetic rats, accompanied by higher levels of Fas expression in the pancreatic islets, serum TNFα, IFNγ, and MDA, but lower levels of SOD and GSH. However, the levels of FBG and frequency of apoptotic islet cells were significantly reduced in OMSS-treated rats. Lower levels of Fas expression were observed in the pancreatic islets of OMSS-treated rats. Significantly reduced levels of serum TNFα, IFNγ, and MDA, but increased levels of SOD and GSH, were detected in OMSS-treated rats.

CONCLUSIONS

Treatment with OMSS significantly reduced FBG in diabetic rats. This antidiabetic activity may be mediated by down-regulating T2DM-related oxidative stress and inflammation, protecting the pancreatic β-cells from apoptosis.