Cytokines in sera from insulin-dependent diabetic patients at diagnosis

Receptors and Signaling Pathways Controlling Beta-Cell Function and Survival as Targets for Anti-Diabetic Therapeutic Strategies

Preserving the function and survival of pancreatic beta-cells, in order to achieve long-term glycemic control and prevent complications, is an essential feature for an innovative drug to have clinical value in the treatment of diabetes. Innovative research is developing therapeutic strategies to prevent pathogenic mechanisms and protect beta-cells from the deleterious effects of inflammation and/or chronic hyperglycemia over time. A better understanding of receptors and signaling pathways, and of how they interact with each other in beta-cells, remains crucial and is a prerequisite for any strategy to develop therapeutic tools aimed at modulating beta-cell function and/or mass. Here, we present a comprehensive review of our knowledge on membrane and intracellular receptors and signaling pathways as targets of interest to protect beta-cells from dysfunction and apoptotic death, which opens or could open the way to the development of innovative therapies for diabetes.

The opportunities and challenges of the disease-modifying immunotherapy for type 1 diabetes: A systematic review and meta-analysis

There are multiple disease-modifying immunotherapies showing the potential of preventing or delaying the progression of type 1 diabetes (T1D). We designed and performed this systematic review and meta-analysis to gain an overview of what a role immunotherapy plays in the treatment of T1D. We searched PubMed, Embase and Cochrane Central Register of Controlled Trials (CENTRAL) from inception to December 2023. We included clinical trials of immunotherapy conducted in patients with T1D that reported the incidence of hypoglycemia or changes from baseline in at least one of following outcomes: 2 h and 4 h mixed-meal-stimulated C-peptide area under the curve (AUC), fasting C-peptide, daily insulin dosage, glycated hemoglobin (HbA1c) and fasting plasma glucose (FPG). The results were computed as the weighted mean differences (WMDs) or odds ratios (ORs) and 95% confidence intervals (CIs) in random-effect model. In all, 34 clinical trials were included. When compared with control groups, 2 h C-peptide AUC was marginally higher in patient treated with nonantigen-based immunotherapies (WMD, 0.04nmol/L, 95% CI, 0.00-0.09 nmol/L, P=0.05), which was mainly driven by the effects of T cell-targeted therapy. A greater preservation in 4 h C-peptide AUC was observed in patients with nonantigen-based immunotherapies (WMD, 0.10nmol/L, 95% CI, 0.04-0.16 nmol/L, P=0.0007), which was mainly driven by the effects of tumor necrosis factor α (TNF-α) inhibitor and T cell-targeted therapy. After excluding small-sample trials, less daily insulin dosage was observed in patient treated with nonantigen-based immunotherapies when compared with control groups (WMD, -0.07units/kg/day, 95% CI, -0.11 to -0.03units/kg/day, P=0.0004). The use of antigen-based immunotherapies was also associated with a lower daily insulin dosage versus control groups (WMD, -0.11units/kg/day, 95% CI, -0.23 to -0.00units/kg/day, P=0.05). However, changes of HbA1c or FPG were comparable between nonantigen-based immunotherapies or antigen-based immunotherapies and control groups. The risk of hypoglycemia was not increased in patients treated with nonantigen-based immunotherapies or patients treated with antigen-based immunotherapies when compared with control groups. In conclusion, nonantigen-based immunotherapies were associated with a preservation of 2 h and 4 h C-peptide AUC in patients with T1D when compared with the controls, which was mainly driven by the effects of TNF-a inhibitor and T cell-targeted therapy. Both nonantigen-based immunotherapies and antigen-based immunotherapies tended to reduce the daily insulin dosage in patients with T1D when compared with the controls. However, they did not contribute to a substantial improvement in HbA1c or FPG. Both nonantigen-based immunotherapies and antigen-based immunotherapies were well tolerated with not increased risk of hypoglycemia in patients with T1D.

Necrosis, netosis, and apoptosis in pulmonary tuberculosis and type-2 diabetes mellitus. Clues from the patient's serum

Pulmonary tuberculosis (PTB) and type 2 diabetes mellitus (T2DM) are two inflammatory diseases whose pathology involves neutrophils (NEU) as key participants. Countless inflammatory elements produced at the lesion sites leak into the blood and are distributed systemically. The study aimed to investigate the effect of the serum of patients with PTB, T2DM, and PTB + T2DM on the cellular and nuclear morphology of healthy NEU. Monolayers of NEU were prepared and incubated with sera from PTB (n꓿ 10), T2DM (n꓿10), PTB + T2DM (n꓿ 10) patients, or sera from healthy people (n = 10). Monolayers were stained for histones, elastase, and myeloperoxidase for NETosis, annexin V for apoptosis, and Iris fuchsia for necrosis. Hoechst stain (DNA) was used to identify the nuclear alterations. Necrosis was the predominant alteration. Sera from PTB + T2DM were the most potent change inducers. Normal sera did not induce cell alterations. The blood of TBP and T2DM patients carries a myriad of abnormal elements that induce necrosis of NEU in normal people, thus reflecting what might occur in the neutrophils of the patients themselves. These findings reinforce the participation of NEU in the pathology of these diseases. Necrosis is expected to be the most frequent neutrophil-induced alteration in tuberculosis and diabetes mellitus.

Pharmacological inhibitors of β-cell dysfunction and death as therapeutics for diabetes

More than 500 million adults suffer from diabetes worldwide, and this number is constantly increasing. Diabetes causes 5 million deaths per year and huge healthcare costs per year. β-cell death is the major cause of type 1 diabetes. β-cell secretory dysfunction plays a key role in the development of type 2 diabetes. A loss of β-cell mass due to apoptotic death has also been proposed as critical for the pathogenesis of type 2 diabetes. Death of β-cells is caused by multiple factors including pro-inflammatory cytokines, chronic hyperglycemia (glucotoxicity), certain fatty acids at high concentrations (lipotoxicity), reactive oxygen species, endoplasmic reticulum stress, and islet amyloid deposits. Unfortunately, none of the currently available antidiabetic drugs favor the maintenance of endogenous β-cell functional mass, indicating an unmet medical need. Here, we comprehensively review over the last ten years the investigation and identification of molecules of pharmacological interest for protecting β-cells against dysfunction and apoptotic death which could pave the way for the development of innovative therapies for diabetes.

Replacing insulin with immunotherapy: Time for a paradigm change in Type 1 diabetes

For almost a hundred years, the management of Type 1 diabetes has not advanced beyond insulin replacement. However, insulin does not provide satisfactory glycaemic control in the majority of individuals and there remains a major unmet need for novel treatments for Type 1 diabetes. Immunomodulation to preserve beta-cell function offers the prospect of making treatment with insulin easier and/or preventing the need for insulin, particularly when it comes to novel low-risk immunotherapies. Led by the concept that the best insulin-producing cell is a patient's own beta-cell, the Type 1 diabetes scientific community has a challenging task ahead-to fundamentally change the management of this devastating disease by using low-risk immunotherapy to preserve endogenous beta-cell function and make metabolic control substantially easier. In that way, insulin and/or beta-cell replacement (stem cell or transplantation) should in the future be considered rescue therapies reserved for delayed presentations.

100 years post-insulin: immunotherapy as the next frontier in type 1 diabetes

Type 1 diabetes (T1D) is an autoimmune disease characterised by T cell-mediated destruction of the insulin-producing β cells in the pancreas. Similar to other autoimmune diseases, the incidence of T1D is increasing globally. The discovery of insulin 100 years ago dramatically changed the outlook for people with T1D, preventing this from being a fatal condition. As we celebrate the centenary of this milestone, therapeutic options for T1D are once more at a turning point. Years of effort directed at developing immunotherapies are finally starting to pay off, with signs of progress in new onset and even preventative settings. Here, we review a selection of immunotherapies that have shown promise in preserving β cell function and highlight future considerations for immunotherapy in the T1D setting.

Golimumab and Beta-Cell Function in Youth with New-Onset Type 1 Diabetes

BACKGROUND

Type 1 diabetes is an autoimmune disease characterized by progressive loss of pancreatic beta cells. Golimumab is a human monoclonal antibody specific for tumor necrosis factor α that has already been approved for the treatment of several autoimmune conditions in adults and children. Whether golimumab could preserve beta-cell function in youth with newly diagnosed overt (stage 3) type 1 diabetes is unknown.

METHODS

In this phase 2, multicenter, placebo-controlled, double-blind, parallel-group trial, we randomly assigned, in a 2:1 ratio, children and young adults (age range, 6 to 21 years) with newly diagnosed overt type 1 diabetes to receive subcutaneous golimumab or placebo for 52 weeks. The primary end point was endogenous insulin production, as assessed according to the area under the concentration-time curve for C-peptide level in response to a 4-hour mixed-meal tolerance test (4-hour C-peptide AUC) at week 52. Secondary and additional end points included insulin use, the glycated hemoglobin level, the number of hypoglycemic events, the ratio of fasting proinsulin to C-peptide over time, and response profile.

RESULTS

A total of 84 participants underwent randomization - 56 were assigned to the golimumab group and 28 to the placebo group. The mean (±SD) 4-hour C-peptide AUC at week 52 differed significantly between the golimumab group and the placebo group (0.64±0.42 pmol per milliliter vs. 0.43±0.39 pmol per milliliter, P<0.001). A treat-to-target approach led to good glycemic control in both groups, and there was no significant difference between the groups in glycated hemoglobin level. Insulin use was lower with golimumab than with placebo. A partial-remission response (defined as an insulin dose-adjusted glycated hemoglobin level score [calculated as the glycated hemoglobin level plus 4 times the insulin dose] of ≤9) was observed in 43% of participants in the golimumab group and in 7% of those in the placebo group (difference, 36 percentage points; 95% CI, 22 to 55). The mean number of hypoglycemic events did not differ between the trial groups. Hypoglycemic events that were recorded as adverse events at the discretion of investigators were reported in 13 participants (23%) in the golimumab group and in 2 (7%) of those in the placebo group. Antibodies to golimumab were detected in 30 participants who received the drug; 29 had antibody titers lower than 1:1000, of whom 12 had positive results for neutralizing antibodies.

CONCLUSIONS

Among children and young adults with newly diagnosed overt type 1 diabetes, golimumab resulted in better endogenous insulin production and less exogenous insulin use than placebo. (Funded by Janssen Research and Development; T1GER ClinicalTrials.gov number, NCT02846545.).

Enhanced STAT3 phosphorylation and PD-L1 expression in myeloid dendritic cells indicate impaired IL-27Ralpha signaling in type 1 diabetes

Interleukin 27 (IL-27), a member of the IL-12 family, is important for T cell differentiation; however, little is known about its effect on dendritic cells (DCs). IL-27 can activate multiple signaling cascades, including the JAK/STAT pathway, and depending on the setting it can both promote and antagonize inflammatory responses. An anti-inflammatory function of IL-27 has been reported in several autoimmune diseases; however, in type 1 diabetes (T1D), an autoimmune disease where autoreactive cytotoxic T cells attack insulin-producing beta cells, IL-27 has been shown to have a dual role and contradictory effects. Here, we show impaired IL-27 signaling in a large cohort of T1D patients (n = 51) compared to age- and gender-matched healthy donors. Increased expression of the IL-27 receptor subunit IL-27Ralpha mRNA in purified myeloid DCs (mDCs), detected by gene expression microarrays was mirrored by enhanced signal transduction in T1D mDCs in response to IL-27 stimulation. Higher STAT phosphorylation in T1D patients was also accompanied by elevated expression of the inhibitory molecules PD-L1, PD-L2 and PD-1, which may suggest not only immunomodulatory mechanisms of IL-27 in T1D but also a compensatory effort of T1D dendritic cells against the ongoing inflammation.

Interleukin-6 and Interleukin-15 as Possible Biomarkers of the Risk of Autoimmune Diabetes Development

Aim

The aim of our study was to assay circulating interleukin-15 (IL-15) and interleukin-6 (IL-6) levels and insulin resistance measured by two different methods in newly diagnosed autoimmune diabetes (AD) patients, their I° relatives, and healthy controls.

Material and Methods

The group studied consisted of 54 patients with AD (28 with Latent Autoimmune Diabetes in Adults (LADA) and 26 with type 1 diabetes (T1D)), 70 first-degree relatives, and 60 controls. IL-6, IL-15, and anti-islet antibodies concentrations were measured by ELISA method. Homeostatic model assessment-insulin resistance (HOMAIR) and estimated glucose disposal rate (eGDR) were calculated.

Results

The patients with AD had significantly higher IL-15, IL-6, and HOMAIR and lower eGDR than the controls (p < 0.001, respectively) and first-degree relatives (p < 0.001, respectively). Significantly higher IL-15 and IL-6 were shown in the relatives with positive Ab as compared to the relatives without antibodies (p < 0.001, respectively) and the controls (p < 0.001, respectively). IL-15 negatively correlated with eGDR (r = −0.436, p = 0.021) in LADA and positively with HOMAIR in LADA and T1D (r = 0.507, p < 0.001; r = 0.4209, p < 0.001).

Conclusions

Significantly higher IL-15 and IL-6 concentrations, HOMAIR, and markedly lower eGDR in newly diagnosed AD patients and first-degree relatives with positive anti-islet antibodies might suggest the role of these pro-inflammatory cytokines and insulin resistance in the pathogenesis of autoimmune diabetes. IL-15 and IL-6 might be used as biomarkers of the risk of autoimmune diabetes development, in particular IL-15 for LADA. Both methods of IR measurement appear equally useful for calculating insulin resistance in autoimmune diabetes.

Metabolic profiling of visceral adipose tissue from obese subjects with or without metabolic syndrome

Obesity represents one of the most complex public health challenges and has recently reached epidemic proportions. Obesity is also considered to be primarily responsible for the rising prevalence of metabolic syndrome, defined as the coexistence in the same individual of several risk factors for atherosclerosis, including dyslipidemia, hypertension and hyperglycemia, as well as for cancer. Additionally, the presence of three of the five risk factors (abdominal obesity, low high-density lipoprotein cholesterol, high triglycerides, high fasting glucose and high blood pressure) characterizes metabolic syndrome, which has serious clinical consequences. The current study was conducted in order to identify metabolic differences in visceral adipose tissue (VAT) collected from obese (body mass index 43-48) human subjects who were diagnosed with metabolic syndrome, obese individuals who were metabolically healthy and nonobese healthy controls. Extensive gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS/MS) analyses were used to obtain the untargeted VAT metabolomic profiles of 481 metabolites belonging to all biochemical pathways. Our results indicated consistent increases in oxidative stress markers from the pathologically obese samples in addition to subtle markers of elevated glucose levels that may be consistent with metabolic syndrome. In the tissue derived from the pathologically obese subjects, there were significantly elevated levels of plasmalogens, which may be increased in response to oxidative changes in addition to changes in glycerolphosphorylcholine, glycerolphosphorylethanolamine glycerolphosphorylserine, ceramides and sphingolipids. These data could be potentially helpful for recognizing new pathways that underlie the metabolic-vascular complications of obesity and may lead to the development of innovative targeted therapies.

Increased Blood Levels of Growth Factors, Proinflammatory Cytokines, and Th17 Cytokines in Patients with Newly Diagnosed Type 1 Diabetes

The production of several cytokines could be dysregulated in type 1 diabetes (T1D). In particular, the activation of T helper (Th) type 1 (Th1) cells has been proposed to underlie the autoimmune pathogenesis of the disease, although roles for inflammatory processes and the Th17 pathway have also been shown. Nevertheless, despite evidence for the role of cytokines before and at the onset of T1D, the corresponding findings are inconsistent across studies. Moreover, conflicting data exist regarding the blood cytokine levels in T1D patients. The current study was performed to investigate genetic and autoantibody markers in association with the peripheral blood cytokine profiles by xMap multiplex technology in newly diagnosed young T1D patients and age-matched healthy controls. The onset of young-age T1D was characterized by the upregulation of growth factors, including granulocyte macrophage-colony stimulating factor (GM-CSF) and interleukin (IL)-7, the proinflammatory cytokine IL-1β (but not IL-6 or tumor necrosis factor [TNF]-α), Th17 cytokines, and the regulatory cytokines IL-10 and IL-27. Ketoacidosis and autoantibodies (anti-IA-2 and -ZnT8), but not human leukocyte antigen (HLA) genotype, influenced the blood cytokine levels. These findings broaden the current understanding of the dysregulation of systemic levels of several key cytokines at the young-age onset of T1D and provide a further basis for the development of novel immunoregulatory treatments in this disease.

Chronic Endotoxemia in Subjects with Type-1 Diabetes Is Seen Much before the Onset of Microvascular Complications

Background

Lipopolysaccharide (LPS)/Endotoxin is hypothesized to play an important role in chronic inflammation associated with Type-1 diabetes (T1DM) and its complications. Endotoxin core antibodies (EndoCAb), LPS binding protein (LBP) and soluble CD14 (sCD14) act as modulators of LPS induced activation of innate immune system in vivo. For the present study we estimated the levels of LPS and its translocation markers in T1DM subjects with and without microvascular complications (MVC) and correlate them with clinical parameters of T1DM and serum inflammatory cytokine levels (TNF-α, IL-6, IL-1β and GM-CSF).

Methods

A total of 197 subjects (64 normal glucose tolerance (NGT) subjects, 97 T1DM subjects without MVC and 36 with MVC) were included in this study and the levels of serum LPS, its translocation markers and cytokines measured by immunoassays.

Results

Compared to NGT, T1DM subjects (both with and without MVC) had significantly higher levels of LPS, reduced levels of LBP and EndoCAb along with significant increase in the levels of IL-1β, IL-6, TNF-α and GM-CSF (p<0.05). No significant change was seen in the levels of these biomarkers between T1DM subjects with and without MVC.

Conclusions

Decreased levels of EndoCAb and LBP suggest sustained endotoxin activity in T1DM subjects even before the onset of microvascular complications.

Rehmannia glutinosa (Gaertn.) DC. polysaccharide ameliorates hyperglycemia, hyperlipemia and vascular inflammation in streptozotocin-induced diabetic mice

ETHNOPHARMACOLOGICAL RELEVANCE

Rehmannia glutinosa (Gaertn.) DC. (RG) has been widely used as traditional Chinese herbal medicine for treatment of diabetes and its complications. The polysaccharide fraction of RG has been proposed to possess hypoglycemic effect by intraperitoneal administration, however, the mechanisms responsible for the hypoglycemic effect of RG polysaccharide (RGP) remain poorly understood. Here we studied the anti-hyperglycemic and anti-hyperlipidemic effect of oral administration of a purified RGP and its underlying mechanisms in streptozotocin (STZ)-induced diabetic mice.

MATERIALS AND METHODS

The preliminary structure of RGP was determined by GC and FT-IR. Mice were injected with STZ to induce type 1 diabetes. RGP at doses of 20, 40 and 80 mg/kg/day was orally administered to mice for 4 weeks, and metformin was used as positive control. After 4 weeks, the blood biochemical parameters, the pancreatic insulin contents, in vitro insulin secretion, the hepatic glycogen contents and mRNA expression of phosphoenolpyruvate carboxyl kinase (PEPCK) were assayed.

RESULTS

RGP was composed of rhamnose, arabinose, mannose, glucose and galactose in the molar ratio of 1.00:1.26:0.73:16.45:30.40 with the average molecular weight of 63.5 kDa. RGP administration significantly decreased the blood levels of glucose, total cholesterol, triglycerides, low density lipoprotein-cholesterol, and increased the blood levels of high density lipoprotein-cholesterol and insulin in diabetic mice, concurrent with increases in body weights and pancreatic insulin contents. The in vitro study revealed that RGP significantly enhanced both basal and glucose-stimulated insulin secretions, as well as islet insulin contents in the pancreatic islets of diabetic mice. Moreover, RGP reversed the increased mRNA expression of PEPCK and the reduced glycogen contents in the liver of diabetic mice. Furthermore, RGP exhibited potent anti-inflammatory and anti-oxidative activities, as evidenced by the decreased blood levels of TNF-α, IL-6, monocyte chemoattractant protein-1, MDA, and also the elevated blood levels of SOD and GPx activities in diabetic mice.

CONCLUSIONS

Taken together, RGP can effectively ameliorate hyperglycemia, hyperlipemia, vascular inflammation and oxidative stress in STZ-induced diabetic mice, and thus may be a potential therapeutic option for type 1 diabetes.

Changes in the levels of cytokines in both diabetic/non-diabetic type I children living in a moderate altitude area in Saudi Arabia

The aim of the present study was to investigate the possible effects of living in moderate altitude area on pro/anti-inflammatory cytokines profile (IFN-γ, TNF-α, IL-6, IL-1β, IL-10, and IL-4) among type I diabetic (T1D) and non- T1D children compared with those living at sea level area. A prospective clinical study was carried out at pediatric outpatient endocrine clinics in Taif City, which is a moderate altitude area in Saudi Arabia, that stands about 1800-2000 meters above sea-level; and in Mecca City, which is a sea level area, that lies in the middle west of Saudi Arabia. Hemoglobin A1c (HbA1c) percentage was estimated and cytokine measurements were performed in sera by flow cytometry using Cytometric Bead Array (CBA) technology. In this study we included 600 children who were consecutively enrolled (sex and age were matched). The HbA1c was statistically significantly higher in children living in moderate altitude compared to those living at sea level (overall p<0.001). Furthermore, T1D patients had higher values of serum cytokine levels (IFN-γ, TNF-α, IL-6, IL-1β, IL-4, and IL-10) in comparison to non-T1D control group (overall p<0.001). In conclusion, the data of the present study clearly showed that in both T1D and non-T1D children, moderate altitude-natives expressed high HbA1c and both pro-and anti-inflammatory cytokines. Type I diabetic children living in moderate altitude or at sea level showed elevated levels of IFN-γ, TNF-α, IL-6, IL-1β, IL-4, and IL-10 than control subjects. Glycemic control in non-diabetic children was affected by living in moderate altitude, however, HbA1c significantly increased in diabetic children living in moderate altitude.

Expression of interleukin-15 and inflammatory cytokines in skeletal muscles of STZ-induced diabetic rats: effect of resistance exercise training

Skeletal muscle atrophy is associated with type-1 diabetes. Skeletal muscle is the source of pro- and anti-inflammatory cytokines that can mediate muscle hypertrophy and atrophy, while resistance exercise can modulate both muscle mass and muscle cytokine expression. This study determined the effects of a 5-week resistance exercise training regimen on the expression of muscle cytokines in healthy and streptozotocin-induced diabetic rats, with special emphasis on interleukin-15 (IL-15), a muscle-derived cytokine proposed to be involved in muscle hypertrophy or responses to stress. Induction of diabetes reduced muscle weight in both the fast flexor hallucis longus (FHL) and slow soleus muscles, while resistance training preserved FHL muscle weight in diabetic rats. IL-15 protein content was increased by training in both FHL and soleus muscles, as well as serum, in normal and diabetic rats. With regard to proinflammatory cytokines, muscle IL-6 levels were increased in diabetic rats, while training decreased muscle IL-6 levels in diabetic rats; training had no effect on FHL muscle IL-6 levels in healthy rats. Also, tumor necrosis factor-alpha (TNF-α) and IL-1β levels were increased by diabetes, but not changed by training. In conclusion, we found that in diabetic rats, resistance training increased muscle and serum IL-15 levels, decreased muscle IL-6 levels, and preserved FHL muscle mass.

Combined losartan and nitro-oleic acid remarkably improves diabetic nephropathy in mice

Diabetic nephropathy (DN) is a leading cause of end-stage renal disease (ESRD). The inhibitors of renin-angiotensin-aldosterone system (RAAS) can alleviate some of the symptoms of DN but fail to stop the progression to ESRD. Our previous studies demonstrate renoprotective action of nitro-oleic acid (OA-NO2) in several rodent models of renal disease. Here we examined the therapeutic potential and the underlying mechanism of combination of losartan and OA-NO2 in db/db mice. OA-NO2 was infused at 5 mg·kg(-1)·day(-1) via osmotic minipump, and losartan was incorporated into diet at 10 mg·kg(-1)·day(-1), each administered alone or in combination for 2 wk. Diabetic db/db mice developed progressive albuminuria and glomerulosclerosis, accompanied by podocytes loss, increased indexes of renal fibrosis, oxidative stress, and inflammation. Treatment of the diabetic mice with OA-NO2 or losartan alone moderately ameliorated kidney injury; however, the combined treatment remarkably reduced albuminuria, restored glomerular filtration barrier structure, and attenuated glomerulosclerosis, accompanied with significant suppression of renal oxidative stress and inflammation. These data demonstrate that combination of losartan and OA-NO2 effectively reverses renal injury in DN.

Effect of iridoid glucoside on plasma lipid profile, tissue fatty acid changes, inflammatory cytokines, and GLUT4 expression in skeletal muscle of streptozotocin-induced diabetic rats

The present study was designed to examine the antihyperlipidaemic potential of iridoid glucoside isolated from Vitex negundo leaves in STZ-induced diabetic rats. The levels of cholesterol (TC), triglycerides, lipoproteins, free fatty acids, phospholipids, fatty acid composition, proinflammatory cytokines, muscle glycogen content, and glucose transporter 4 (GLUT4) expression were estimated in control and diabetic rats. Oral administration of iridoid glucoside at a dose of 50 mg/kg body weight per day to STZ-induced diabetic rats for a period of 30 days resulted in a significant reduction in plasma and tissue (liver and kidney) cholesterol, triglycerides, free fatty acids, and phospholipids. In addition, the decreased plasma levels of high-density lipoprotein-cholesterol and increased plasma levels of low density lipoprotein- and very low density lipoprotein-cholesterol in diabetic rats were restored to near normal levels following treatment with iridoid glucoside. The fatty acid composition of the liver and kidney was analyzed by gas chromatography. The altered fatty acid composition in the liver and kidney of diabetic rats was also restored upon treatment with iridoid glucoside. Moreover, the elevated plasma levels of proinflammatory cytokines and decreased levels of muscle glycogen and GLUT4 expression in the skeletal muscle of diabetic rats were reinstated to their normal levels via enhanced secretion of insulin from the remnant β cells of pancreas by the administration of iridoid glucoside. The effect produced by iridoid glucoside on various parameters was comparable with that of glibenclamide, a well-known antihyperglycemic drug.

Serum titres of anti-glutamic acid decarboxylase-65 and anti-IA-2 autoantibodies are associated with different immunoregulatory milieu in newly diagnosed type 1 diabetes patients

Several studies correlated genetic background and pancreatic islet-cell autoantibody status (type and number) in type 1A diabetes mellitus (T1AD), but there are no data evaluating the relationship among these markers with serum cytokines, regulatory T cells and β cell function. This characterization has a potential importance with regard to T1AD patients' stratification and follow-up in therapeutic prevention. In this study we showed that peripheral sera cytokines [interleukin (IL)-12, IL-6, II-1β, tumour necrosis factor (TNF)-α, IL-10] and chemokines (CXCL10, CXCL8, CXCL9, CCL2) measured were significantly higher in newly diagnosed T1AD patients when compared to healthy controls (P < 0·001). Among T1AD, we found a positive correlation between CXCL10 and CCL-2 (r = 0·80; P = 0·000), IL-8 and TNF-α (r = 0·60; P = 0·000); IL-8 and IL-12 (r = 0·57; P = 0·001) and TNF-α and IL-12 (r = 0·93; P = 0·000). Glutamic acid decarboxylase-65 (GAD-65) autoantibodies (GADA) were associated negatively with CXCL10 (r = -0·45; P = 0·011) and CCL2 (r = -0·65; P = 0·000), while IA-2A showed a negative correlation with IL-10 (r = -0·38; P = 0·027). Human leucocyte antigen (HLA) DR3, DR4 or DR3/DR4 and PTPN22 polymorphism did not show any association with pancreatic islet cell antibodies or cytokines studied. In summary, our results revealed that T1AD have a proinflammatory cytokine profile compared to healthy controls and that IA-2A sera titres seem to be associated with a more inflammatory peripheral cytokine/chemokine profile than GADA. A confirmation of these data in the pre-T1AD phase could help to explain the mechanistic of the well-known role of IA-2A as a more specific marker of beta-cell damage than GADA during the natural history of T1AD.

Nuclear factor-κB1 controls the functional maturation of dendritic cells and prevents the activation of autoreactive T cells

Mature dendritic cells (DCs) are crucial for the induction of adaptive immune responses and perturbed DC homeostasis can result in autoimmune disease. Either uncontrolled expansion or enhanced survival of DCs can result in a variety of autoimmune diseases in mouse models. In addition, increased maturation signals, through overexpression of surface Toll-like receptors (TLRs) or stimulation by type I interferon (IFN), has been associated with systemic autoimmunity. Whereas recent studies have focused on identifying factors required for initiating the maturation process, the possibility that resting DCs also express molecules that 'hold' them in an immature state has generally not been considered. Here we show that nuclear factor-κB1 (NF-κB1) is crucial for maintaining the resting state of DCs. Self-antigen-pulsed unstimulated DCs that do not express NF-κB1 were able to activate CD8(+) T lymphocytes and induce autoimmunity. We further show that NF-κB1 negatively regulates the spontaneous production of tumor necrosis factor-α (TNF-α), which is associated with increased granzyme B expression in cytotoxic T lymphocytes (CTLs). These findings provide a new perspective on functional DC maturation and a potential mechanism that may account for pathologic T cell activation.

Does Vitamin E and C Supplementation Improve the Recovery From Anterior Cruciate Ligament Surgery?

Muscular (quadriceps) weakness is a predominant impairment that follows anterior cruciate ligament injury and surgery. This continued weakness impairs activities of daily living and could predispose patients to adverse conditions later in life, such as knee osteoarthritis. Vitamins E and C have potent antioxidant and anti-inflammatory activity. Herein, the authors summarize the state-of-the science and suggest directions for future research endeavors regarding the therapeutic influence of vitamins E and C, or other antioxidants, on the recovery from anterior cruciate ligament injury and surgery.

Etanercept treatment in children with new-onset type 1 diabetes: pilot randomized, placebo-controlled, double-blind study

OBJECTIVE

To gather preliminary data on the feasibility and efficacy of etanercept therapy to prolong endogenous insulin production in pediatric patients with newly diagnosed type 1 diabetes.

RESEARCH DESIGN AND METHODS

This was a 24-week double-blind, randomized, placebo-controlled study conducted at the Diabetes Center, Women and Children's Hospital of Buffalo. Eighteen subjects (11 male and 7 female, aged 7.8-18.2 years) were randomly assigned to receive either placebo or etanercept. Inclusion criteria included age 3-18 years, GAD-65 and/or islet cell antibody positivity, A1C >6%, three insulin injections per day, white blood cell count 3,000-10,000, platelets >100,000, and normal liver and renal function. Intention-to-treat analysis was used.

RESULTS

A1C at week 24 was lower in the etanercept group (5.91 +/- 0.5%) compared with that in the placebo group (6.98 +/- 1.2%; P < 0.05) with a higher percent decrease from baseline than in the placebo group (etanercept 0.41 +/- 0.1 vs. placebo 0.18 +/- 0.21; P < 0.01). The percent change in C-peptide area under the curve from baseline to week 24 showed a 39% increase in the etanercept group and a 20% decrease in the placebo group (P < 0.05). From baseline to week 24 insulin dose decreased 18% in the etanercept group compared with a 23% increase in the placebo group (P < 0.05). Seventeen patients completed the study, and none withdrew because of adverse events.

CONCLUSIONS

In this small pilot study, treatment of pediatric patients newly diagnosed with type 1 diabetes with etanercept resulted in lower A1C and increased endogenous insulin production, suggesting preservation of beta-cell function. A larger study is needed to further explore safety and efficacy.

Chromium supplementation enhances insulin signalling in skeletal muscle of obese KK/HlJ diabetic mice

AIM

Chromium is an essential nutrient required for glucose and lipid metabolism. Laboratory and clinical evidences indicate that chromium supplementation may improve insulin sensitivity by enhancing intracellular signalling. Considerable evidence suggests that serine phosphorylation of insulin receptor substrate 1 (IRS1) at 307 residue (IRS1-Ser307) inhibits insulin signalling and results in peripheral insulin resistance. Therefore, we investigated whether chromium-associated insulin action was mediated by modulation of IRS1-Ser307 phosphorylation.

METHODS

Male KK/HlJ mice (genetically obese and insulin resistant) were supplemented daily with chromium-containing milk powder or placebo for 7 weeks. In analysing functionally characterized insulin resistance, the changes of blood biochemicals, inflammatory factors and insulin signalling molecules in skeletal muscle were analysed.

RESULTS

Using KK mice model, we demonstrated that daily supplementation of trivalent chromium-containing milk powder reduced serum levels of glucose, insulin and triglycerides, and improved glucose and insulin tolerance. Mechanistic study showed that chromium supplementation activated postreceptor insulin signalling such as increasing IRS1, IRS1 tyrosine phosphorylation, p85alpha regulatory subunit of phosphatidylinositol 3-kinase and glucose transporter 4 expression, stimulating Akt activity, downregulating c-Jun N-terminal kinase (JNK) activity and decreasing IRS1 ubiquitinization and insulin resistance-associated IRS1 phosphorylation (IRS1-Ser307) in skeletal muscle. In addition, chromium supplementation attenuated pro-inflammatory cytokine expression in both blood circulation and skeletal muscle.

CONCLUSION

Our data suggest that chromium-containing milk powder supplementation can provide a beneficial effect in diabetic subjects by enhancing insulin signalling in skeletal muscle. The improvement in insulin signalling by chromium was associated with the decreased IRS1-Ser307 phosphorylation, JNK activity and pro-inflammatory cytokine production.

Possible association between obesity and posttransplantation complications including infectious diseases and acute graft-versus-host disease

Both obesity and malnutrition are considered risk factors for complications after bone marrow transplantation (BMT). To elucidate the impact of pretransplantation body mass index (BMI) on clinical outcome, we performed a retrospective cohort study with registration data from the Japan Marrow Donor Program (JMDP). Between January 1998 and December 2005, a total of 3935 patients received unrelated BMT through the JMDP; of these, 3827 patients for whom pretransplantation height and weight data were available were included in the study. Patients were stratified according to pretransplantation BMI values (low BMI: BMI < 18 kg/m(2), n = 295; normal BMI: 18 < or = BMI < 25 kg/m(2), n = 2906; overweight: 25 < or = BMI <30 kg/m(2), n = 565; obese: 30 kg/m(2) < or = BMI, n = 61). In a univariate analysis, pretransplantation BMI was associated with a significantly greater risk of grade II-IV acute graft-versus-host disease (GVHD; P = .03). Multivariate analysis showed that pretransplantation BMI tended to be associated with an increased risk of grade II-IV acute GVHD (P = .07). Obesity was associated with an increased risk of infection compared with normal BMI (odds ratio = 1.9; 95% confidence interval = 1.1 to 3.2; P = .02). Our findings demonstrate a correlation between pretransplantation BMI and posttransplantation complications. Although BMI depends strongly on multiple factors, the effect of obesity on clinical outcome should be evaluated in a prospective study.

Hyperglycemia during the neutropenic period is associated with a poor outcome in patients undergoing myeloablative allogeneic hematopoietic stem cell transplantation

BACKGROUND

Recipients of allogeneic hematopoietic stem cell transplantation (HSCT) frequently require support with parenteral nutrition and immunosuppressive drugs, which introduce the risk of hyperglycemia. Van den Berghe et al. showed that the strict glucose control improved the outcome of patients treated in the intensive care unit, and this point was evaluated in this study in a HSCT setting.

METHODS

A cohort of 112 consecutive adult patients treated by myeloablative allogeneic HSCT between January 2002 and June 2006 was reviewed retrospectively. Twenty-one patients were excluded due to graft failure, preexisting infectious diseases, preexisting neutropenia or previous allogeneic HSCT. The remaining 91 patients were categorized according to mean fasting blood glucose (BG) level in the neutropenic period after conditioning: normoglycemia (BG <110 mg/dL, n=28), mild hyperglycemia (110 to 150 mg/dL, n=49), and moderate/severe (>150 mg/dL, n=14). The primary endpoint was the occurrence of febrile neutropenia (FN) and documented infection during neutropenia, and the secondary endpoints included organ dysfunction according to the definition used by van den Berghe, acute graft-versus-host disease (GVHD), overall survival, and nonrelapse mortality (NRM).

RESULTS

Although the incidence of FN or documented infections was similar between the three groups, hyperglycemia was significantly associated with an increased risk of organ dysfunction, grade II-IV acute GVHD, and NRM.

CONCLUSIONS

While the results suggested an association between the degree of hyperglycemia during neutropenia and an increased risk of posttransplant complications and NRM, the possibility that intensive glucose control improves the outcome after HSCT can only be confirmed in a prospective randomized trial.

Effect of chromium niacinate and chromium picolinate supplementation on lipid peroxidation, TNF-alpha, IL-6, CRP, glycated hemoglobin, triglycerides, and cholesterol levels in blood of streptozotocin-treated diabetic rats

Chromium (Cr(3+)) supplementation facilitates normal protein, fat, and carbohydrate metabolism, and is widely used by the public in many countries. This study examined the effect of chromium niacinate (Cr-N) or chromium picolinate (Cr-P) supplementation on lipid peroxidation (LP), TNF-alpha, IL-6, C-reactive protein (CRP), glycosylated hemoglobin (HbA(1)), cholesterol, and triglycerides (TG) in diabetic rats. Diabetes (D) was induced in Sprague-Dawley rats by streptozotocin (STZ) (ip, 65 mg/kg BW). Control buffer, Cr-N, or Cr-P (400 microg Cr/kg BW) was administered by gavages daily for 7 weeks. Blood was collected by heart puncture using light anesthesia. Diabetes caused a significant increase in blood levels of TNF-alpha, IL-6, glucose, HbA(1), cholesterol, TG, and LP. Compared with D, Cr-N supplementation lowered the blood levels of TNF-alpha (P=0.04), IL-6 (P=0.02), CRP (P=0.02), LP (P=0.01), HbA(1) (P=0.02), TG (P=0.04), and cholesterol (P=0.04). Compared with D, Cr-P supplementation showed a decrease in TNF-alpha (P=0.02), IL-6 (P=0.02), and LP (P=0.01). Chromium niacinate lowers blood levels of proinflammatory cytokines (TNF-alpha, IL-6, CRP), oxidative stress, and lipids levels in diabetic rats, and appears to be a more effective form of Cr(3+) supplementation. This study suggests that Cr(3+) supplementation can lower the risk of vascular inflammation in diabetes.

Glucose intolerance modifies the inflammatory response after intestinal ischemia-reperfusion

Streptozotocin administration in newborn rats (nSTZ-rats) leads to adults with mild insulin deficiency and normoglycemia, and is accepted as a model of type 2 diabetes. We examined possible differences in the production of inflammatory mediators between healthy and nSTZ-rats after ischemia-reperfusion (I-R). Two-month-old control and nSTZ-rats were randomly separated into control and intestinal I-R groups. After reperfusion, samples were obtained from the portal vein (PV) infrahepatic cava vein (ICV), suprahepatic cava vein (SCV), jejunal wall, and pancreas. Nitric oxide (NO), lipid hydroperoxides (LPO), tumor necrosis factor alpha (TNF-alpha), 60 kDa receptor (sTNF-R1), 80 kDa (sTNF-R2), and intercellular adhesion molecule-1 (ICAM-1), were determined. After I-R, nSTZ-rats showed increased plasma concentrations of LPO, NO, ICAM-1 (0.5141 +/- 0.083 vs 0.024 +/- 0.003, ICV; 0.574 +/- 0.075 vs 0.023 +/- 0.003, SCV; 0.528 +/- 0.067 vs 0.027 +/- 0.003 PV; ng/ml), TNF-alpha (42.4 +/- 5.7 ICV, 248.4 +/- 28.2 SCV, and 33.6 +/- 4.0 PV. In n STZ-rats, vs 4.36 +/- 0.57, 4.74 +/- 0.77, and 3.16 +/- 0.32, respectively, in control rats; pg/ml), and sTNF-R1. Both TNF-alpha and NO plasma levels were higher in SCV than in ICV and PV after I-R. In addition, after I-R, jejunal wall of nSTZ-rats showed an increase of TNF-alpha IL-1, and IL-10 levels. A pre-existing state of glucose intolerance intensifies the inflammatory response after intestinal I-R.

Tumor necrosis factor-alpha in diabetic plasma increases the activity of core 2 GlcNAc-T and adherence of human leukocytes to retinal endothelial cells: significance of core 2 GlcNAc-T in diabetic retinopathy

A large body of evidence now implicates increased leukocyte-endothelial cell adhesion as a key early event in the development of diabetic retinopathy. We recently reported that raised activity of the glycosylating enzyme core 2 beta 1,6-N-acetylglucosaminyltransferase (GlcNAc-T) through protein kinase C (PKC)beta2-dependent phosphorylation plays a fundamental role in increased leukocyte-endothelial cell adhesion and capillary occlusion in retinopathy. In the present study, we demonstrate that following exposure to plasma from diabetic patients, the human promonocytic cell line U937 exhibits a significant elevation in core 2 GlcNAc-T activity and increased adherence to cultured retinal capillary endothelial cells. These effects of diabetic plasma on enzyme activity and cell adhesion, mediated by PKCbeta2-dependent phosphorylation of the core 2 GlcNAc-T protein, were found to be triggered by increased plasma levels of tumor necrosis factor (TNF)-alpha. Levels of enzyme activity in plasma-treated U937 cells were closely dependent on the severity of diabetic retinopathy, with the highest values observed upon treatment with plasma of patients affected by proliferative retinopathy. Furthermore, we noted much higher correlation, as compared with control subjects, between increased values of core 2 GlcNAc-T activity and cell adhesion properties. Based on the prominent role of TNF-alpha in the development of diabetic retinopathy, these observations further validate the significance of core 2 GlcNAc-T in the pathogenesis of capillary occlusion, thereby enhancing the therapeutic potential of specific enzyme inhibitors.

Effect of thalidomide and rosiglitazone on the prevention of diabetic retinopathy in streptozotocin-induced diabetic rats

AIMS/HYPOTHESIS

Our aim was to compare the therapeutic effect of thalidomide and rosiglitazone on the prevention of diabetic retinopathy in streptozotocin-induced diabetic rats.

METHODS

Male Holtzman rats of 6 to 8 weeks of age and weighing 170+/-30 g were randomly divided into four groups: control ( n=13), untreated diabetic ( n=17) and diabetic rats treated with thalidomide (200 mg kg(-1) day(-1)) ( n=8) or rosiglitazone (1 mg kg(-1) day(-1)) ( n=22) for 3 months. Diabetes was induced by streptozotocin with the rats having a body weight of 70 mg/kg. After treatment, vascular endothelial growth factor (VEGF) concentrations in ocular fluid were compared between the different groups, and retinal capillary basement membrane thickness was measured by electron microscopy.

RESULTS

Higher VEGF concentrations in ocular fluid and thicker basement membranes were observed in untreated diabetic rats compared to the control rats. Similar VEGF concentrations and basement membrane thickness were observed for the thalidomide-treated group compared with the control group, whereas no difference in these parameters was observed between the rosiglitazone-treated rats and the control or untreated diabetic rats.

CONCLUSIONS/INTERPRETATION

Our findings confirm the association between VEGF concentrations and diabetic retinopathy as suggested by other investigators. Thalidomide, but not rosiglitazone, was associated with the inhibition of basement membrane thickening and the blockade of the increase of VEGF in ocular fluid, thus representing a potential therapeutic drug for the prevention of diabetic retinopathy.

An association of autoantibody status and serum cytokine levels in type 1 diabetes

At onset of type 1 diabetes, the islet autoantibody status of patients has been reported to predict progression of the disease. We therefore tested the hypothesis that the systemic immunoregulatory balance, as defined by levels of circulating cytokines and chemokines, is associated with islet autoantibody status. In 50 patients with recent-onset type 1 diabetes, antibodies to GAD and insulinoma-associated antigen 2 (IA-2) were analyzed by radioimmunoassay; cytoplasmic islet cell antibodies were determined by indirect immunofluorescence. Cytokine and chemokine concentrations were measured by rigidly evaluated double antibody enzyme-linked immunosorbent assay. Of four classically defined Th1/Th2 cytokines (gamma-interferon, interleukin [IL]-5, IL-10, IL-13), none showed an association with multiple autoantibody positivity. Of six mediators mainly produced by innate immunity cells, three were associated with multiple autoantibody status (IL-18 increased, MIF and MCP-1 decreased) and three were unaffected (IL-12, MIP-1beta, IP-10). GAD and/or IA-2 antibody titers negatively correlated with systemic concentrations of MIF, MIP-1beta, and IL-12. Combining the data of several cytokine and chemokine levels made it possible to predict islet antibody positivity in individual patients with 85% sensitivity and 94% specificity. These data suggest a close association of islet antibody status with systemic immunoregulation in type 1 diabetes.

Prospects for the prevention and reversal of type 1 diabetes mellitus

Type 1 (insulin-dependent) diabetes mellitus results from selective immune-mediated destruction of pancreatic islet beta cells. Strategies to prevent or reverse the development of diabetes can be divided into three groups, depending on whether they focus on beta-cell protection, regeneration or replacement. Prevention of immune beta-cell destruction involves either halting the immune attack directed against beta cells or making beta cells better able to withstand immune attack, for example, by making them resistant to free radical damage. The recent identification of beta-cell growth factors and development of stem cell technologies provides an alternative route to the reversal of diabetes, namely beta-cell regeneration. Interestingly, stem cell-derived islets appear to be less sensitive to recurrent immune destruction that is normally seen in response to islet transplantation. The last alternative is beta-cell replacement or substitution. This covers a wide range of interventions including human whole pancreas transplantation, xenotransplantation, genetically modified beta cells, mechanical insulin sensing and delivery devices, and the artificial pancreas. This review describes recent advances in each of these research areas and aims to provide clinicians with an idea of where and when an effective strategy to prevent or reverse diabetes development will become available.

Macrophages from high-risk HLA-DQB1*0201/*0302 type 1 diabetes mellitus patients are hypersensitive to lipopolysaccharide stimulation

Levels of nonantigen-induced pro-inflammatory cytokines and prostaglandin in macrophages isolated from human leucocyte antigen (HLA)-matched type 1 diabetes mellitus patients, first-degree relatives and healthy controls were determined. We hypothesize that monocytes isolated from patients are sensitized or preactivated and therefore, have an altered response to in vitro stimulus compared with control groups as measured by levels of pro- and anti-inflammatory mediators. In this study, peripheral blood monocytes were differentiated to macrophages with macrophage-colony stimulating factor (M-CSF) to determine lipopolysaccharide (LPS)-stimulated tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-6, IL-12 and prostaglandin E-2 (PGE-2) secretion from hetero- or homozygous HLA DQB1*0201 and *0302 type 1 diabetes mellitus patients, first-degree relatives and homozygous HLA DQB1*0602 healthy controls. LPS-stimulated secretion of TNF-alpha, IL-1beta and IL-6 was immediate and markedly higher in the HLA-DQB1*0201/*0302 type 1 diabetes patients compared with all other groups including HLA-matched healthy first-degree relatives. In DQB1*0201/*0302 diabetes patients PGE-2 secretion was delayed but increased by LPS stimulation compared with HLA-matched healthy relatives. IL-12 was not detected at any condition. These data suggest that macrophages from DQB1*0201/*0302 type 1 diabetes patients are sensitized to secrete both cytokines and PGE-2 following nonantigenic stimulation. Sensitized macrophages may be important to high-risk DQB1*0201/*0302-associated type 1 diabetes.

Hyperketonemia increases tumor necrosis factor-alpha secretion in cultured U937 monocytes and Type 1 diabetic patients and is apparently mediated by oxidative stress and cAMP deficiency

An elevated blood level of tumor necrosis factor (TNF)-alpha is a validated marker of vascular inflammation, which can result in the development of vascular disease and atherosclerosis. This study examined the hypothesis that ketosis increases the TNF-alpha secretion, both in a cell culture model using U937 monocytes and in type 1 diabetic patients in vivo. U937 cells were cultured with ketone bodies (acetoacetate [AA] and beta-hydroxybutyrate [BHB]) in the presence or absence of high levels of glucose in medium at 37 degrees C for 24 h. This study demonstrates the following points. First, hyperketonemic diabetic patients have significantly higher levels of TNF-alpha than normoketonemic diabetic patients (P < 0.01) and normal control subjects (P < 0.01). There was a significant correlation (r = 0.36, P < 0.05; n = 34) between ketosis and oxidative stress as well as between oxidative stress and TNF-alpha levels (r = 0.47, P < 0.02; n = 34) in the blood of diabetic patients. Second, ketone body AA treatment increases TNF-alpha secretion, increases oxygen radicals production, and lowers cAMP levels in U937 cells. However, BHB did not have any effect on TNF-alpha secretion or oxygen radicals production in U937 cells. Third, exogenous addition of dibutyryl cAMP, endogenous stimulation of cAMP production by forskolin, and antioxidant N-acetylcysteine (NAC) prevented stimulation of TNF-alpha secretion caused by AA alone or with high glucose. Similarly, NAC prevented the elevation of TNF-alpha secretion and lowering of cAMP levels in H(2)O(2)-treated U937 cells. Fourth, the effect of AA on TNF-alpha secretion was inhibited by specific inhibitors of protein kinase A (H89), p38-mitogen-activated protein kinase (SB203580), and nuclear transcription factor (NF)kappaB (NFkappaB-SN50). This study demonstrates that hyperketonemia increases TNF-alpha secretion in cultured U937 monocytic cells and TNF-alpha levels in the blood of type 1 diabetic patients and is apparently mediated by AA-induced cellular oxidative stress and cAMP deficiency.

Chromium chloride inhibits oxidative stress and TNF-alpha secretion caused by exposure to high glucose in cultured U937 monocytes

Chromium supplementation has been proposed to promote the action of insulin and the lowering of blood glucose levels in diabetic patients. However, the molecular mechanism by which chromium increases insulin sensitivity is not known. Using U937 monocytes as a cell culture model, this study demonstrates that chromium inhibits the secretion of TNF-alpha, a cytokine known to inhibit the sensitivity and action of insulin. U937 cells were cultured with high levels of glucose (mimicking diabetes) in the presence or absence of chromium chloride in the medium at 37 degrees C for 24 h. This study demonstrates that chromium supplementation prevents the increase in TNF-alpha levels and oxidative stress caused by the high levels of glucose in cultured U937 monocytic cells. Similarly, chromium supplementation prevented elevated TNF-alpha secretion and lipid peroxidation levels in H(2)O(2)-treated U937 cells. This study demonstrates for the first time that chromium supplementation inhibits TNF-alpha secretion in U937 monocytes cultured in high-glucose medium, which appears to be mediated by its antioxidative effect. This provides evidence for a novel molecular mechanism by which chromium supplementation may increase insulin sensitivity and glycemic control in diabetic patients.

Cytokine expression in unstimulated PBMC of children with type 1 diabetes and subjects positive for diabetes-associated autoantibodies

The aim of this study was to evaluate possible changes in the circulating levels of interferon (IFN)-gamma, interleukin (IL)-4 and transforming growth factor (TGF)-beta in association with the autoimmune process leading to type 1 diabetes. Expression levels of mRNAs specific for each cytokine were determined in peripheral blood mononuclear cells (PBMC) by a multiplex reverse transcription-polymerase chain reaction (RT-PCR) followed by hybridization reactions with lanthanide-labelled probes and detection by time-resolved fluorometry. Newly diagnosed diabetic children had lower levels of IFN-gamma, IL-4 and TGF-beta 1 signals compared to their age- and sex-matched controls (P < 0.02, P < 0.005 and P < 0.005, respectively) and also the autoantibody-positive subjects had significantly lower levels of IL-4 and TGF-beta 1 in comparison with their matched controls (P = 0.0013 and P = 0.012). No significant differences were observed when comparing matched pairs of diabetic children and autoantibody-positive subjects. Our results suggest a systemic bias towards reduced production of T-helper cell type 2 cytokines (IL-4 and TGF-beta 1) during the autoimmune process, but there was also a reduced level of IFN-gamma expression in the periphery at the onset of clinical diabetes.

Elevated serum IP-10 levels observed in type 1 diabetes

OBJECTIVE

Although most patients with type 1 diabetes are considered to have T-cell-mediated autoimmune disease, a method of measuring of pancreatic beta-cell-specific T-cell function in cases of type 1 diabetes has yet to be established. Here, we focused on interferon-inducible protein-10 (IP-10), a chemokine that promotes the migration of activated T-helper 1 (Th1) cells and measured serum IP-10 levels in patients with human type 1 diabetes, which is regarded as a Th1-mediated disease.

RESEARCH DESIGN AND METHODS

Serum samples were obtained from diabetic patients, and the levels of autoantibodies (GAD and insulinoma-associated protein-2 [IA-2]) and IP-10 were measured. Diabetic patients positive for either or both of the autoantibodies were classified as Ab+ type 1, and those negative for both were classified as Ab type 1. To evaluate islet antigen-specific responses, peripheral blood from patients stimulated with or without GAD was used, and intracellular cytokine staining for flowcytometry was performed.

RESULTS

The Ab+ and Ab- type 1 groups both showed a significantly higher serum IP-10 level than the healthy subjects (P < 0.001 and P < 0.05, respectively), and the IP-10 level in the recent-onset Ab+ subgroup was significantly higher than that in the established (longstanding) Ab+ subgroup (P < 0.002). Furthermore, there was a significant positive correlation between the serum IP-10 level and the number of GAD-reactive gamma-interferon-producing CD4+ cells in the Ab+ type 1 group (P < 0.007).

CONCLUSIONS

Our findings demonstrate that measurement of serum IP-10 concentrations is useful in patients with type 1 diabetes.

Cytokine production in NOD mice on prophylactic insulin therapy

We investigated whether cytokines produced primarily by monocytes/macrophages (IL-1alpha), Th1-lymphocytes (IFNgamma), or Th2-lymphocytes (IL-4) are modulated in diabetes-prone NOD mice by insulin treatment as used in prophylaxis studies. The cytokines were measured by ELISA in plasma and in supernatants of spleen cells activated ex vivo by lipopolysaccharide plus phytohemagglutinin. Insulin, 0.25-0.50 IU/day, was given subcutaneously for 8 weeks starting in 4-week-old female mice. The insulin-treated and control NOD mice showed similar weight gains and, by the end of the study, both groups exhibited cell infiltration in about 25% of their islets. IL-1alpha, IFNgamma and IL-4 were generally below detection in plasma of prediabetic animals and controls. Diabetic NOD mice, aged 28-45 weeks, had significantly elevated plasma IL-1alpha: 154+/-39 pg/ml (mean+/-SEM, p<0.0001). While ex vivo activated NOD splenocytes released similar amounts of IL-1alpha, insulin therapy increased the levels from 99+/-17 to 155+/-19 pg/10(6) cells (p<0.05). Supernatants of activated splenocytes from prediabetic NOD mice had lower levels of IL-4 (<15 pg/10(6) cells) compared with those from BALB/c mice (88+/-22 pg/10(6) cells; p<0.01), and this deficiency was partially compensated for when the NOD mice were given insulin (27+/-8; p<0.01). The levels of IFNgamma were comparable and largely unaffected by insulin treatment. Hence, insulin therapy appears to partially normalize an otherwise deficient Th2 response in NOD mice.

Systemic levels of cytokines and GAD-specific autoantibodies isotypes in Chinese IDDM patients

It is not clear if a Th1/Th2 imbalance in Type 1 diabetes (insulin-dependent diabetes mellitus, IDDM) would lead to a particular antigen-specific IgG subclass dominant as had been shown in the mouse model. In new-onset Type 1 diabetics, an autoantibody response to glutamate decarboxylase (GADab) is frequently observed but the GADab subclass repertoire is not well-established. We determined the systemic levels of representative Th1 and Th2 cytokines and the GADab IgG subclass distribution in 41 Chinese IDDM patients of whom 26 were recently diagnosed (< or = 1 year) and 32 had GADab, to ascertain a likely association of antigen-specific antibody isotype and the Th1/Th2 dichotomy. With high-sensitivity ELISA systems that measure sub-picogram cytokine concentrations, 26 of the 41 patients (63.4%) had at least one of the pro-inflammatory Th1 cytokines (TNF-alpha, IFN-gamma and IL-12) detected. Fewer patients (4/41) had the anti-inflammatory Th2 cytokine IL-4 detected. For IL-10, all subjects had measurable quantities but only three diabetics had levels above the upper limit for healthy subjects (n = 20). Grouped according to the profile of detectable cytokines, there were 24 Th1, 2 Th2 and 2 Th0 patterns. GAD-specific IgG1 antibody was more frequently expressed; 22 of 32 GADab[+] patients. The rank order for the GADab subclasses was IgG1 > 4 > 3 > 2; IgG2 was found in 11 GADab[+] patients. Recent-onset diabetics have a similar ranking of the GAD-specific IgG subclasses. In human Type 1 diabetes, a predominance of GAD-specific IgG1 antibody response is observed together with a dominant Th1 cytokine pattern.

Decreased secretion of Th2 cytokines precedes Up-regulated and delayed secretion of Th1 cytokines in activated peripheral blood mononuclear cells from patients with insulin-dependent diabetes mellitus

Recent evidence suggests that autoimmune animal diabetes is associated with an imbalance between the Th1 and Th2 arms of the cellular immune system. However, limited data is available regarding the Th1/Th2 imbalance in human Insulin dependent diabetes mellitus (IDDM) patients. Therefore, we examined the peak levels, secretory pattern and total cytokine production (calculated as the area under the curve, AUC) of the Th1 cytokines, IL-2 and IFN-gamma, and Th2 cytokines, IL-4 and IL-10, from stimulated peripheral blood mononuclear cells, from 17 IDDM patients and 24 normal controls. In contrast to controls, diabetic patients were characterized by an early, uniformly low secretion of Th2 cytokines, followed by a late increased secretion of Th1 cytokines. This resulted in significant differences in secretory patterns of IFN-gammaIL-2, IL-4 and IL-10 between the two groups; P<0.001, P<0.005, P<0.005 and P<0.001, respectively. No correlation was found in the diabetic patients between any profiles of the cytokines and their various clinical parameters, including age, gender, disease duration, insulin requirements or glycated hemoglobin levels. In conclusion, our data provides the first comprehensive evidence for an independent and persistent impairment of both Th1 and Th2 cytokine secretory patterns in IDDM patients.

Prevention of type 1 diabetes

This article discusses type 1 diabetes mellitus, which results from insulin deficiency caused by autoimmune destruction of the insulin-producing beta-cells in the pancreatic islets of Langerhans. The autoimmune response against islet beta-cells is believed to result from a disorder of immunoregulation. According to this concept, T lymphocytes (T cells) autoreactive to certain beta-cell constituents exist normally but are restrained by regulatory (suppressor) T cells. Activation of beta-cell autoreactive T cells together with deficient regulatory T cell responses is believed to result in clonal expansion of autoreactive T cells, and these cells may elicit a cascade of beta-antigen specific (T cell) immune and nonspecific inflammatory responses that destroy islet beta-cells. Islet beta-cells autoreactive T cells seem to secrete type 1 cytokines, whereas regulatory T cells may secrete type 2 and type 3 cytokines; therefore, type 1 diabetes may result from a relative dominance of type 1 cytokines over type 2 and type 3 cytokines. These concepts derive mainly from studies in animal models with spontaneous autoimmune diabetes, and the evidence in humans with type 1 diabetes is sparse. Nevertheless, the concept of type 1 diabetes as a disorder of immunoregulation has spurred clinical trials of diabetes prevention based on strategies directed at diverting the immune response from autoimmunity to self-tolerance, for example, by administration of beta-cell autoantigens, and by attempting to tip the immune balance in favor of the production or action of type 2 and type 3 cytokines over type 1 cytokines.

Cytokines and their roles in pancreatic islet beta-cell destruction and insulin-dependent diabetes mellitus

Insulin-dependent diabetes mellitus (IDDM) is a disease that results from autoimmune destruction of the insulin-producing beta-cells in the pancreatic islets of Langerhans. The autoimmune response against islet beta-cells is believed to result from a disorder of immunoregulation. According to this concept, a T helper 1 (Th1) subset of T cells and their cytokine products, i.e. Type 1 cytokines--interleukin 2 (IL-2), interferon gamma (IFNgamma), and tumor necrosis factor beta (TNFbeta), dominate over an immunoregulatory (suppressor) Th2 subset of T cells and their cytokine products, i.e. Type 2 cytokines--IL-4 and IL-10. This allows Type 1 cytokines to initiate a cascade of immune/inflammatory processes in the islet (insulitis), culminating in beta-cell destruction. Type 1 cytokines activate (1) cytotoxic T cells that interact specifically with beta-cells and destroy them, and (2) macrophages to produce proinflammatory cytokines (IL-1 and TNFalpha), and oxygen and nitrogen free radicals that are highly toxic to islet beta-cells. Furthermore, the cytokines IL-1, TNFalpha, and IFNgamma are cytotoxic to beta-cells, in large part by inducing the formation of oxygen free radicals, nitric oxide, and peroxynitrite in the beta-cells themselves. Therefore, it would appear that prevention of islet beta-cell destruction and IDDM should be aimed at stimulating the production and/or action of Type 2 cytokines, inhibiting the production and/or action of Type 1 cytokines, and inhibiting the production and/or action of oxygen and nitrogen free radicals in the pancreatic islets.

Relationship of polymorphonuclear leukocytes to capillary dropout in the human diabetic choroid

Capillary dropout is an initial event in diabetic retinopathy, but the etiology is unknown. Recent evidence suggests that similar events may occur in the diabetic choroid. We have developed a method to evaluate the relationship between the polymorphonuclear leukocytes (PMNs) and capillary dropout in the human diabetic choroid using alkaline phosphatase (APase) histochemistry to label blood vessels and nonspecific esterase activity to identify PMNs. The number and distribution of PMNs in diabetic and nondiabetic choroidal capillaries (choriocapillaris) were analyzed in the flat perspective and the tissue then flat embedded in glycol methacrylate for histological sectioning. The total number of PMNs was increased within the choriocapillaris in five diabetic eyes (170.9 +/- 12.9 PMNs/mm2 of choroid) compared with five nondiabetic eyes (84.2 +/- 16.9 PMNs/mm2; P < 0.001). PMNs were almost always within blood vessel lumens and not in interstitial tissue. In the diabetic choroid, increased numbers of PMNs were present in areas of choriocapillaris with pathological changes (loss in APase activity and choroidal neovascularization) compared with nonpathological choriocapillaris (205.1 +/- 46.9 PMNs/mm2 in pathological versus 152.3 +/- 23.4 PMNs/mm2 in nonpathological areas; P < 0.001). PMNs were often queued up within the lumens of capillaries, demonstrating loss in APase activity. We have observed an increased number of PMNs in diabetic choroid compared with control nondiabetic choroids, and PMNs in diabetic choroid were associated with loss in APase activity, which was related to loss in viable endothelial cells. The results suggest that PMNs contribute to vaso-occlusive processes and endothelial cell injury in the diabetic choroid.

Synthesis and secretion of tumour necrosis factor-alpha by human monocytic THP-1 cells and chemotaxis induced by human serum albumin derivatives modified with methylglyoxal and glucose-derived advanced glycation endproducts

Human serum albumin minimally-modified by methylglyoxal (MGmin-HSA) stimulated the synthesis and secretion of tumour necrosis factor-alpha (TNF-alpha) from human monocytic THP-1 cells in vitro. Human serum albumin minimally-modified by glucose-derived advanced glycation endproducts (AGEmin-HSA) and human serum albumin highly-modified by glucose-derived advanced glycation endproducts (AGE-HSA) stimulated markedly lower synthesis and secretion of TNF-alpha from THP-1 cells than did MGmin-HSA. The median effective concentration EC50 value of MGmin-HSA for the secretion of TNF-alpha was 5.8 +/- 0.3 microM and the maximal secretion was 0.28 +/- 0.01 ng TNF-alpha/ml (n = 12) for incubations containing 5 x 10(5) cells/ml. MGmin-HSA (0.2-2.0 microM) also stimulated chemotaxis of THP-1 cells in vitro but AGE-HSA did not in this concentration range. The EC50 value of MGmin-HSA for the chemotactic response was 0.44 +/- 0.07 microM (n = 15). Similar induction of the synthesis and secretion of TNF-alpha and chemotaxis by monocytes in response to MGmin-HSA in vivo may contribute to atherosclerosis in macro- and micro-angiopathy, particularly in the development of chronic clinical complications of diabetes mellitus.

Fusidic acid and insulin-dependent diabetes mellitus

Insulin-dependent diabetes mellitus (IDDM) is a major cause of morbidity and mortality from long-standing complications. The autoimmune nature of IDDM has encouraged use of immunosuppressive and antiinflammatory strategies to better preserve residual pancreatic beta-cell function at the time of diagnosis. Fusidic acid and its sodium salt, fusidin, is a relatively atoxic antibiotic used mainly in the treatment of staphylococcal infections. Recently, fusidin has been demonstrated to possess immunosuppressive functions in vitro and in vivo, and the drug has shown promise in preventing the disease in animal models of IDDM and in a preliminary trial in IDDM patients.

Elevated serum levels of macrophage-derived cytokines precede and accompany the onset of IDDM

To determine whether cytokines could have a role in the development of insulin-dependent diabetes mellitus (IDDM), we measured serum levels of cytokines derived from T helper 1 (interleukin-2 and interferon-gamma), T helper 2 (interleukin-4 and interleukin-10) lymphocytes and macrophages (tumour necrosis factor-alpha, interleukin-1 alpha and interleukin-1 beta) in patients before and after the onset of IDDM. Recently diagnosed IDDM patients had significantly higher levels of interleukin-2, interferon-gamma, tumour necrosis factor-alpha and interleukin-1 alpha than patients with either long-standing IDDM, non-insulin-dependent diabetes (NIDDM), Graves' disease, or control subjects (p < 0.05 for all). Compared with control subjects, patients with long-standing IDDM and those with NIDDM had higher interleukin-2 and tumour necrosis factor-alpha levels (p < 0.01 for all). Interleukin-4 and interleukin-10 were detectable in sera of patients with Graves' disease only, while interleukin-1 beta was not detectable in the serum of any control or test subject. To investigate whether high cytokine levels precede the onset of IDDM, we studied 28 non-diabetic identical co-twins of patients with IDDM, followed-up prospectively for up to 6 years after the diagnosis of the index. Levels of tumour necrosis factor-alpha and interleukin-1 alpha were elevated above the normal range more frequently in the eight twins who developed diabetes than in those 20 who did not (p < 0.005). Analysis of T helper 1 and T helper 2 profiles of the twin groups did not reveal a clear difference between prediabetic twins and twins remaining non-diabetic. These results support the notion that T helper 1 lymphocytes may play a role in the development of IDDM. This is associated with release of macrophage-derived cytokines, which is also a feature of the prediabetic period. The lack of evidence of a dominant T helper 1 profile of cytokine release before diabetes onset suggests that additional events, activating this arm of the cellular immune response, are required in the immediate prediabetic period.

Enhanced expression of intracellular adhesion molecule-1 and P-selectin in the diabetic human retina and choroid

Elevated expression of intercellular adhesion molecule-1 (ICAM-1) as well as E- and P-selectin occurs on the vascular endothelium in a number of disease states and is thought to play an early critical role in the adhesion of circulating leukocytes to the endothelium. The goal of the present study was to investigate the immunolocalization of these molecules in the retina and choroid of postmortem human tissue sections from nondiabetic and diabetic subjects. Whereas ICAM-1 was localized primarily within the choriocapillaris of nondiabetic subjects, immunoreactivity in diabetics was significantly elevated throughout the choroidal vasculature and within retinal blood vessels (P < 0.05). In the choroid, P-selectin was most prominent in veins of the nondiabetic, whereas in diabetics, P-selectin was significantly elevated in arteries (P < 0.001) and veins (P < 0.05) and, in some cases, was also observed in choriocapillaris. P-selectin immunoreactivity was not observed in the retina of any subject. E-selectin immunoreactivity was not observed in choroid or retina in any subjects. Neutrophil numbers per square millimeter of tissue were significantly elevated in diabetic choroid (P < 0.05) and retina (P < 0.001). Our results demonstrate that ICAM-1 and P-selectin are constitutively expressed in the normal choroid and are upregulated in the choroidal vasculature in diabetes, but only ICAM-1 was upregulated in the retina of diabetic subjects. Increased cell adhesion molecule expression may contribute to the retinal and choroidal microangiopathy observed in diabetics by enhancing leukocyte adhesion and consequently the incidence of capillary obstruction and endothelial cell injury.