Lentinan confers protection against type 1 diabetes by inducing regulatory T cell in spontaneous non-obese diabetic mice.

BACKGROUND: Lentinan (LNT) is a complex fungal component that possesses effective antitumor and immunostimulating properties. However, there is a paucity of studies regarding the effects and mechanisms of LNT on type 1 diabetes. OBJECTIVE: In the current study, we investigated whether an intraperitoneal injection of LNT can diminish the risk of developing type 1 diabetes (T1D) in non-obese diabetic (NOD) mice and further examined possible mechanisms of LNT's effects. METHODS: Pre-diabetic female NOD mice 8 weeks of age, NOD mice with 140-160 mg/dL, 200-230 mg/dL or 350-450 mg/dL blood glucose levels were randomly divided into two groups and intraperitoneally injected with 5 mg/kg LNT or PBS every other day. Then, blood sugar levels, pancreas slices, spleen, PnLN and pancreas cells from treatment mice were examined. RESULTS: Our results demonstrated that low-dosage injections (5 mg/kg) of LNT significantly suppressed immunopathology in mice with autoimmune diabetes but increased the Foxp3+ regulatory T cells (Treg cells) proportion in mice. LNT treatment induced the production of Tregs in the spleen and PnLN cells of NOD mice in vitro. Furthermore, the adoptive transfer of Treg cells extracted from LNT-treated NOD mice confirmed that LNT induced Treg function in vivo and revealed an enhanced suppressive capacity as compared to the Tregs isolated from the control group. CONCLUSION: LNT was capable of stimulating the production of Treg cells from naive CD4 + T cells, which implies that LNT exhibits therapeutic values as a tolerogenic adjuvant and may be used to reverse hyperglycaemia in the early and late stages of T1D.

Syntaxin 4 Enrichment in ß-Cells Prevents Conversion to Autoimmune Diabetes in Non-Obese Diabetic (NOD) Mice.

Syntaxin 4 (STX4), a plasma membrane-localized SNARE protein, regulates human islet ß-cell insulin secretion and preservation of ß-cell mass. We found that human type 1 diabetes (T1D) and NOD mouse islets show reduced ß-cell STX4 expression, consistent with decreased STX4 expression, as a potential driver of T1D phenotypes. To test this hypothesis, we generated inducible ß-cell-specific STX4-expressing NOD mice (NOD-ißSTX4). Of NOD-ißSTX4 mice, 73% had sustained normoglycemia vs. <20% of control NOD (NOD-Ctrl) mice by 25 weeks of age. At 12 weeks of age, before diabetes conversion, NOD-ißSTX4 mice demonstrated superior whole-body glucose tolerance and ß-cell glucose responsiveness than NOD-Ctrl mice. Higher ß-cell mass and reduced ß-cell apoptosis were also detected in NOD-ißSTX4 pancreata compared with pancreata of NOD-Ctrl mice. Single-cell RNA sequencing revealed that islets from NOD-ißSTX4 had markedly reduced interferon-γ signaling and tumor necrosis factor-α signaling via nuclear factor-κB in islet ß-cells, including reduced expression of the chemokine CCL5; CD4+ regulatory T cells were also enriched in NOD-ißSTX4 islets. These results provide a deeper mechanistic understanding of STX4 function in ß-cell protection and warrant further investigation of STX4 enrichment as a strategy to reverse or prevent T1D in humans or protect ß-cell grafts.

The changes in immune cell concentration during the progression of pre-diabetes to type 2 diabetes in a high-fat high-carbohydrate diet-induced pre-diabetic rat model.

Pre-diabetes is a long-lasting condition that precedes type 2 diabetes (T2D). T2D has been shown to suppress the immune response. However, it remains unclear if immune activation occurs before the onset of T2D during the progression of the pre-diabetic state. This study sought to characterize the changes in general immunity occurring during the progression from pre-diabetes to T2D. Male rats were fed a high-fat high-carbohydrate diet for 20 weeks (pre-diabetes induction period) and kept on the same diet being monitored for a further 12 weeks (experimental period). Blood was collected for haemocytometer analysis on week 0, 4, 8, and 12 of the experimental period after which the animals were sacrificed. Plasma was collected from centrifuged blood for ELISA (TNF-α, CRP, P-selectin, CD40 L, fibrinogen, and IL-6). Blood neutrophils percentage significantly decreased at week 12 possibly due to recruited neutrophils migrating to an inflamed area such as visceral adipose tissue as further observed. Due to hyperglycaemia, there was significant increase in blood lymphocytes percentage at week 12. Blood monocytes percentage significantly increased at week 12. Monocytes recruited and circulated in blood due to hyperglycaemia for glucose uptake to decrease it from circulation. Blood eosinophils percentage significantly decreased at week 12. Eosinophils migrated to inflamed areas such as visceral adipose tissue as further observed. Blood basophils percentage significantly increased due to their recruitment and activation. TNF-α, CRP, and IL-6 increased significantly after 12 weeks. There was also upregulation of fibrinogen, P-selectin, and CD40L. The results of this study show that there are changes in immune cells concentration and that immune cells such as neutrophils and eosinophils migrate to inflamed areas such as adipose tissue. There is also upregulation of various inflammatory cytokines. Based on these findings, immune activation begins during the pre-diabetic state as there is upregulation of inflammatory markers.

Relationship between natural killer cell activity and glucose control in patients with type 2 diabetes and prediabetes.

AIMS/INTRODUCTION: Natural killer (NK) cells are cytotoxic lymphocytes critical to human immunity. Previous studies showed correlations between NK cell function and blood glucose concentrations. The purpose of the present study was to assess the NK cell activity and various metabolic parameters in people with type 2 diabetes, prediabetes and normal glucose tolerance. MATERIALS AND METHODS: A total of 49 participants were enrolled in the study. Anthropometric and biochemical parameters including age, sex, body mass index, smoking status, blood pressure, fasting plasma glucose, C-peptide, insulin, glycated hemoglobin, total cholesterol, triglyceride, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol were assessed. The 75 g oral glucose tolerance test was carried out for 2-h postload glucose level. Homeostatic model assessment was calculated for insulin resistance and ß-cell function. NK cell activity was measured by detecting the circulating interferon-gamma level secreted from NK cells. RESULTS: NK cell activity was lower in patients with type 2 diabetes (768.01 ± 650.35) compared with those with prediabetes (2,396.08 ± 653.76, P < 0.001) and normal glucose tolerance (2,435.31 ± 633.22, P < 0.001). In patients with type 2 diabetes, there was a significant inverse linear relationship between NK cell activity and fasting plasma glucose, glycated hemoglobin, and 2-h postload glucose level (all P < 0.001). Multiple regression analysis showed glycated hemoglobin to be an independent predictor of NK cell activity in patients with type 2 diabetes. CONCLUSIONS: Compared with individuals with normal glucose tolerance or prediabetes, type 2 diabetes patients have a reduced NK cell activity, and it is significantly related to glucose control.

Impact of short-term exercise training intensity on ß-cell function in older obese adults with prediabetes.

The effect of work-matched exercise intensity on ß-cell function is unknown in people with prediabetes before clinical weight loss. We determined if short-term moderate continuous (CONT) vs. high-intensity interval (INT) exercise increased ß-cell function. Thirty-one subjects (age: 61.4 ± 2.5 yr; body mass index: 32.1 ± 1.0 kg/m2) with prediabetes [American Diabetes Association criteria, 75-g oral glucose tolerance test (OGTT)] were randomized to work-matched CONT (70% HRpeak) or INT (3 min 90% HRpeak and 3 min 50% HRpeak) exercise for 60 min/day over 2 wk. A 75-g 2-h OGTT was conducted after an overnight fast, and plasma glucose, insulin, C-peptide, and free fatty acids were determined for calculations of skeletal muscle [oral minimal model (OMM)], hepatic (homeostatic model of insulin resistance), and adipose (Adipose-IR) insulin sensitivity. ß-Cell function was defined from glucose-stimulated insulin secretion (GSIS, deconvolution modeling) and the disposition index (DI). Glucagon-like polypeptide-1 [GLP-1(active)] and glucose-dependent insulinotropic polypeptide (GIP) were also measured during the OGTT, along with peak oxygen consumption and body composition. CONT and INT increased skeletal muscle- but not hepatic- or adipose-derived DI ( P < 0.05). Although both treatments tended to reduce fasting GLP-1(active) ( P = 0.08), early phase GLP-1(active) increased post-CONT and INT training ( P < 0.001). Interestingly, CONT exercise increased fasting GIP compared with decreases in INT ( P = 0.02). Early and total-phase skeletal muscle DI correlated with decreased total glucose area under the curve ( r = -0.52, P = 0.002 and r = -0.50, P = 0.003, respectively). Independent of intensity, short-term training increased pancreatic function adjusted to skeletal muscle in relation to improved glucose tolerance in adults with prediabetes. Exercise also uniquely affected GIP and GLP-1(active). Further work is needed to elucidate the dose-dependent mechanism(s) by which exercise impacts glycemia. NEW & NOTEWORTHY Exercise is cornerstone for reducing blood glucose, but whether high-intensity interval training is better than moderate continuous exercise is unclear in people with prediabetes before weight loss. We show that 2 wk of exercise training, independent of intensity, increased pancreatic function in relation to elevated glucagon-like polypeptide-1 secretion. Furthermore, ß-cell function, but not insulin sensitivity, was also correlated with improved glucose tolerance. These data suggest that ß-cell function is a strong predictor of glycemia regardless of exercise intensity.

Reduced mitochondrial DNA content in lymphocytes is associated with insulin resistance and inflammation in patients with impaired fasting glucose.

Altered mitochondrial DNA (mtDNA) is the most common denominator to numerous metabolic diseases. The present study sought to investigate the correlation between mtDNA content in lymphocytes and associated clinical risk factors for impaired fasting glucose (IFG). We included 23 healthy control and 42 IFG participants in this cross-sectional study. The measurements of mtDNA content in lymphocytes and pro-inflammatory markers derived from both normal and diseased individuals were quantified. Spearman partial correlation and multivariate statistical analyses were employed to evaluate the association between mtDNA content and other metabolic covariates in IFG. Reduced mtDNA content was observed in the IFG group with microvascular complications than those without complications. The IFG patients with lowest median of mtDNA content had considerably elevated hyperglycemia, insulin resistance and inflammation. The adjusted partial correlation analysis showed that mtDNA content was positively correlated with HDL-cholesterol and IL-10 (P < 0.005 for all). Further, multiple linear regression analyses verified that reduced mtDNA content in lymphocytes was independently associated with HOMA-IR (ß = 0.027, P = 0.003), HbA1c (ß = 0.652, P = 0.002), HDL-cholesterol (ß = - 1.056, P = 0.021), IL-6 (ß = 0.423, P = 0.002), IL-10 (ß = - 1.234, P = 0.043) and TNF-α (ß = 0.542, P < 0.001) after adjustment for confounding factors. Our data show that reduced mtDNA content in lymphocytes was associated with insulin resistance and inflammation in individuals with IFG.

Analysis of Inflammatory Mediators in Prediabetes and Newly Diagnosed Type 2 Diabetes Patients.

This study evaluated the inflammatory markers in prediabetes and newly diagnosed type 2 diabetes mellitus (T2DM). Inflammatory markers levels were analyzed using one-way analysis of covariance and the association with prediabetes or T2DM risks was examined by logistic regression models. Our data showed increased levels of hypersensitivity C-reactive protein (hs-CRP), interleukin (IL-4), IL-10, and tryptase in prediabetes subjects and hs-CRP, immunoglobulin E (IgE), IL-4, and IL-10 in T2DM subjects. We concluded that Hs-CRP, IgE, IL-4, IL-10, and tryptase were positively associated with prediabetes or T2DM. Further large prospective studies are warranted to assess a temporal relation between inflammatory biomarkers and incidence of prediabetes or T2DM and its associated chronic diseases.

Low Level Pro-inflammatory Cytokines Decrease Connexin36 Gap Junction Coupling in Mouse and Human Islets through Nitric Oxide-mediated Protein Kinase Cδ.

Pro-inflammatory cytokines contribute to the decline in islet function during the development of diabetes. Cytokines can disrupt insulin secretion and calcium dynamics; however, the mechanisms underlying this are poorly understood. Connexin36 gap junctions coordinate glucose-induced calcium oscillations and pulsatile insulin secretion across the islet. Loss of gap junction coupling disrupts these dynamics, similar to that observed during the development of diabetes. This study investigates the mechanisms by which pro-inflammatory cytokines mediate gap junction coupling. Specifically, as cytokine-induced NO can activate PKCδ, we aimed to understand the role of PKCδ in modulating cytokine-induced changes in gap junction coupling. Isolated mouse and human islets were treated with varying levels of a cytokine mixture containing TNF-α, IL-1ß, and IFN-γ. Islet dysfunction was measured by insulin secretion, calcium dynamics, and gap junction coupling. Modulators of PKCδ and NO were applied to determine their respective roles in modulating gap junction coupling. High levels of cytokines caused cell death and decreased insulin secretion. Low levels of cytokine treatment disrupted calcium dynamics and decreased gap junction coupling, in the absence of disruptions to insulin secretion. Decreases in gap junction coupling were dependent on NO-regulated PKCδ, and altered membrane organization of connexin36. This study defines several mechanisms underlying the disruption to gap junction coupling under conditions associated with the development of diabetes. These mechanisms will allow for greater understanding of islet dysfunction and suggest ways to ameliorate this dysfunction during the development of diabetes.

Estrogen Therapy Delays Autoimmune Diabetes and Promotes the Protective Efficiency of Natural Killer T-Cell Activation in Female Nonobese Diabetic Mice.

Therapeutic strategies focused on restoring immune tolerance remain the main avenue to prevent type 1 diabetes (T1D). Because estrogens potentiate FoxP3+ regulatory T cells (Treg) and invariant natural killer T (iNKT) cells, two regulatory lymphocyte populations that are functionally deficient in nonobese diabetic (NOD) mice, we investigated whether estradiol (E2) therapy influences the course of T1D in this model. To this end, female NOD mice were sc implanted with E2- or placebo-delivering pellets to explore the course of spontaneous and cyclophosphamide-induced diabetes. Treg-depleted and iNKT-cell-deficient (Jα18(-/-)) NOD mice were used to assess the respective involvement of these lymphocyte populations in E2 effects. Early E2 administration (from 4 wk of age) was found to preserve NOD mice from both spontaneous and cyclophosphamide-induced diabetes, and a complete protection was also observed throughout treatment when E2 treatment was initiated after the onset of insulitis (from 12 wk of age). This delayed E2 treatment remained fully effective in Treg-depleted mice but failed to entirely protect Jα18(-/-) mice. Accordingly, E2 administration was shown to restore the cytokine production of iNKT cells in response to in vivo challenge with the cognate ligand α-galactosylceramide. Finally, transient E2 administration potentiated the previously described protective action of α-galactosylceramide treatment in NOD females. This study provides original evidence that E2 therapy strongly protects NOD mice from T1D and reveals the estrogen/iNKT cell axis as a new effective target to counteract diabetes onset at the stage of insulitis. Estrogen-based therapy should thus be considered for T1D prevention.

Interleukin-10 gene transfer into insulin-producing ß cells protects against diabetes in non-obese diabetic mice.

Type 1 diabetes is an autoimmune disorder, which occurs due to ß cell damage. Interleukin (IL)-10, a pleotropic cytokine, has been reported to have anti­inflammatory, immunosuppressive and immunostimulatory properties. Administration of IL­10 is known to prevent autoimmune diabetes in non­obese diabetic (NOD) mice. However, the mechanism of IL­10­induced protection in NOD mice requires further investigation. The aim of the present study was to evaluate the protective effect of transgenic IL­10 expression in pancreatic ß cells against autoimmune damage in NOD mice and to elucidate its mechanism of action. Female NOD mice (9 weeks old) were intraperitoneally injected with an adenovirus carrying either IL­10 (Adv­IL­10) or green fluorescent protein (Adv­GFP). Blood glucose was monitored weekly and the expression of IL­10 was evaluated using reverse transcription quantitative polymerase chain reaction. IL­10 and interferon (IFN)­Î³ expression levels in serum and splenocytes were analyzed. CD4+CD25+FoxP3+ T regulatory (Treg) cells were determined by flow cytometry. Apoptosis of pancreatic ß cells was determined using a terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick­end labeling assay and expression levels of Fas and caspase­3 were estimated by immunohistochemistry analysis. The results revealed that mice treated with IL­10 showed less severe insulitis and a lower incidence of diabetes compared with the saline control and Adv­GFP groups. In addition, compared with the control group, IFN­Î³ levels were decreased in sera and splenocytes, while IL­10 expression was increased in sera only. The number of CD4+CD25+FoxP3+ Treg cells was increased in IL­10­injected mice. Furthermore, the expression levels of Fas and caspase­3 were decreased in IL­10­injected mice compared with that of GFP­injected and control mice, which was concomitant with a reduction in ß cell apoptosis. In conclusion, the present study demonstrated that IL­10 gene transfer reduced the expression of the inflammatory cytokines, attenuated pancreatic insulitis and inhibited ß cell apoptosis. This therefore indicated that IL-10 reduced the incidence of diabetes in female NOD mice.

Periodontal Status and Whole Salivary Cytokine Profile Among Smokers and Never-Smokers With and Without Prediabetes.

BACKGROUND: Whole salivary interleukin (IL)-1ß and IL-6 in smokers and never-smokers with prediabetes remains uninvestigated. The aim of this study is to assess the periodontal status and whole salivary IL-1ß and IL-6 levels among smokers and never-smokers with and without prediabetes (controls). METHODS: Ninety-five males (45 with prediabetes and 50 systemically healthy controls) were included. Twenty-seven controls and 29 patients with prediabetes were smokers. Periodontal parameters (plaque index, bleeding on probing, probing depth, clinical attachment loss, and marginal bone loss) were measured, and the number of missing teeth were recorded. Fasting blood glucose (FBG) and hemoglobin A1c (HbA1c) levels were recorded. Unstimulated whole saliva samples were collected, unstimulated whole salivary flow rate (UWSFR) was determined, and IL-1ß and IL-6 levels were measured. P values <0.05 were considered statistically significant. RESULTS: FBG (P <0.05) and HbA1c (P <0.05) levels were higher among patients with prediabetes than controls. All patients with prediabetes were hyperglycemic. UWSFR was significantly higher among controls than among patients with prediabetes (P <0.05). Periodontal parameters and whole salivary IL-1ß and IL-6 levels were comparable among smokers and never-smokers with prediabetes. Among controls, periodontal parameters and whole salivary IL-1ß and IL-6 levels were higher among smokers than never-smokers (P <0.05). CONCLUSIONS: Among controls, periodontal inflammation was worse, and whole salivary IL-1ß and IL-6 levels are higher in smokers than never-smokers. Among patients with prediabetes, periodontal inflammation and whole salivary IL-1ß and IL-6 levels were comparable between smokers and never-smokers.

Electrochemiluminescence assays for insulin and glutamic acid decarboxylase autoantibodies improve prediction of type 1 diabetes risk.

We recently developed new electrochemiluminescence (ECL) insulin autoantibody (IAA) and glutamic acid decarboxylase 65 autoantibody (GADA) assays that discriminate high-affinity, high-risk diabetes-specific autoantibodies from low-affinity, low-risk islet autoantibodies (iAbs) detected by radioassay (RAD). Here, we report a further validation of the ECL-IAA and -GADA assays in 3,484 TrialNet study participants. The ECL assay and RAD were congruent in those with prediabetes and in subjects with multiple autoantibodies, but only 24% (P<0.0001) of single RAD-IAA-positive and 46% (P<0.0001) of single RAD-GADA-positive were confirmed by the ECL-IAA and -GADA assays, respectively. During a follow-up (mean, 2.4 years), 51% of RAD-IAA-positive and 63% of RAD-GADA-positive subjects not confirmed by ECL became iAb negative, compared with only 17% of RAD-IAA-positive (P<0.0001) and 15% of RAD-GADA-positive (P<0.0001) subjects confirmed by ECL assays. Among subjects with multiple iAbs, diabetes-free survival was significantly shorter if IAA or GADA was positive by ECL and negative by RAD than if IAA or GADA was negative by ECL and positive by RAD (P<0.019 and P<0.0001, respectively). Both positive and negative predictive values in terms of progression to type 1 diabetes mellitus were superior for ECL-IAA and ECL-GADA, compared with RADs. The prevalence of the high-risk human leukocyte antigen-DR3/4, DQB1*0302 genotype was significantly higher in subjects with RAD-IAA or RAD-GADA confirmed by ECL. In conclusion, both ECL-IAA and -GADA are more disease-specific and better able to predict the risk of progression to type 1 diabetes mellitus than the current standard RADs.

Unfavorable inflammatory profile in adults at risk of type 2 diabetes identified by hemoglobin A1c levels according to the American Diabetes Association criteria.

AIMS: We aimed to evaluate the inflammatory profile of individuals with prediabetes defined by HbA1c levels, according to the new American Diabetes Association criteria, and to determine the ability of HbA1c to identify individuals with subclinical inflammation independently of the contribution of other metabolic parameters such as fasting, 1- or 2-h post-load glucose (PG) levels. METHODS: High sensitivity C-reactive protein (hsCRP), erythrocyte sedimentation rate (ESR), fibrinogen, white blood cells (WBC) count and complement C3 (C3) were assessed, and oral glucose tolerance test (OGTT) was performed in 711 adults. RESULTS: Subjects were stratified into three groups according to their HbA1c levels. Poor agreement existed between HbA1c and 2-h PG criteria for identification of individuals with prediabetes (κ coefficient = 0.300). As compared with subjects having HbA1c <5.7 % (39 mmol/mol), individuals with prediabetes (HbA1c 5.7-6.4 %, [39-46 mmol/mol]) exhibited a significant increase of the concentration of five inflammatory markers (hsCRP, ESR, fibrinogen, WBC count, C3) as well as of a cluster of inflammatory markers, as measured by an inflammatory score after adjusting for sex, age, smoking, fasting, 1- and 2-h PG levels. In multiple regression models including sex, age, body mass index, smoking habit, fasting, 1- and 2-h PG levels, and HOMA index, HbA1c levels were significant independent contributors to each of the five inflammatory markers examined. CONCLUSIONS: These data suggest that HbA1c is a reliable marker of glucose homeostasis, and may identify individuals at increased risk of diabetes with unfavorable inflammatory profile independently from fasting and 2-h PG levels.

Islet-associated T-cell receptor-ß CDR sequence repertoire in prediabetic NOD mice reveals antigen-driven T-cell expansion and shared usage of VßJß TCR chains.

Autoimmune destruction of pancreatic islets in the nonobese diabetic (NOD) mouse is driven by T cells recognizing various autoantigens mostly in insulin-producing beta-cells. To investigate if T-cell accumulation in islets during early insulitis is clonally predetermined, we compared the complementarity determining regions (CDR3) of T-cell receptor (TCR)ß-chains present in islet-infiltrating T cells in young prediabetic NOD mice. High-throughput sequencing of TCRß-chain DNA extracted from islets of 7-wk old NOD mice revealed a biased TCRß-chain repertoire in all mice, as a restricted number of clones (17-36 clones) was highly overrepresented and made over 20% of total islet repertoire in each mouse. Among these clones, various Vß and Jß families were present but certain VßJß combinations such as TRBV19-0-TRBJ2-7 and TRBV13-3-TRBJ2-5 were highly shared between individual mice. On TCRß-chain CDR sequence level, many islet clones (72-146) were shared between at least two individual mice. None of them was among expanded clones in both, suggesting considerable stochasticity in the interactions between TCR and peptide-MHC, even with a limited range of autoantigens. A comparison of islet-CDR3-sequences with CRD-sequences from other tissues revealed clonal overlap with pancreatic lymph node and gut, but these repertoires did not overlap together. Our results suggest that antigen-specific T cells are expanded in pancreatic lymph node and islets, but different specificities expand in individual mice. Some islet-infiltrating T-cell specificities may have a distinct origin shared with gut-infiltrating T cells.

Monocytes, but not T cells, respond to insulin with Akt(S473) phosphorylation independent of the donor glucometabolic state.

BACKGROUND: Obesity is associated with insulin resistance and chronic low-grade inflammation. Insulin has been described to have anti-inflammatory effects in immune cells. Therefore, insulin resistance in immune cells can be expected to have important consequences for immune function. Here, we investigate whether freshly isolated monocytes and T cells, isolated from study subjects with a normal or disturbed glucometabolic state, respond to insulin with phosphorylation of Akt, a key molecule in the insulin signalling pathway. METHODS: A total of 25 study subjects were enrolled in the study. An oral glucose tolerance test (OGTT) was performed, and from fasting insulin and glucose, the homeostasis model assessment of insulin resistance (HOMA-IR) index was calculated. Peripheral blood mononuclear cells were isolated from heparinized blood and phenotypically characterized by flow cytometry. Basal and insulin-induced fractions of pAkt(S473)-positive monocytes and T cells were determined by Phosflow. RESULTS: On the basis of the OGTT, 11 subjects were classified as normal glucose tolerant (NGT), 9 had an impaired glucose metabolism (IGM) and 5 had type 2 diabetes (T2DM). The fraction of pAkt(S473)positive-T cells and monocytes, in the absence of insulin, was low in all subjects. Incubation with insulin did not induce Akt phosphorylation in CD4⁺ and CD8⁺ T cells in normal subjects. However, in the monocyte fraction, an insulin-dose-dependent increase of the pAkt(S473)positive-cell fraction was observed. This response did not differ between NGT, IGM and T2DM and was not correlated with HOMA-IR. CONCLUSIONS: In this study, we show that freshly isolated monocytes, but not T cells, are insulin-sensitive cells and that this insulin sensitivity of monocytes is not negatively affected by the glucometabolic state of the donor.

Hepatitis C virus and type 1 diabetes.

Hepatitis C virus infection and diabetes mellitus are two worldwide, major public health problems with increasing complication and mortality rates. Type 1 diabetes mellitus (T1D) is characterized by an autoimmune process leading to pancreatic beta cell destruction; only when the major part of pancreatic beta cells have been destroyed the diabetes become clinically manifest. At the basis of the development of the T1D there is an interplay among environmental factors, pancreatic beta cells, the innate and adaptive immune system, the genetic background and the comorbidities of the patient. Viral infections, including hepatitis C virus infection, may be one of the factors that can almost accelerate progression to diabetes, through different mechanisms.

Monocyte-macrophage polarization balance in pre-diabetic individuals.

Pre-diabetes is characterized by increased cardiovascular risk and chronic inflammation. The activation of monocyte-macrophages plays major roles in vascular biology. Herein, we aimed to analyze monocyte-macrophage polarization status in subjects with IFG and/or IGT compared with normal glucose tolerant (NGT) individuals. We enrolled 87 middle-aged individuals with low prevalence of cardiovascular disease. Based on OGTT, they were divided into 49 NGT and 38 pre-diabetic (IFG and/or IGT). Using flow cytometry analysis of peripheral blood cells, we quantified traditional monocyte subsets based on CD14 and CD16 expression as well as novel monocyte-macrophage pro-inflammatory CD68(+)CCR2(+) M1 and anti-inflammatory CX3CR1(+)CD163(+)/CD206(+) M2 phenotypes. The M1/M2 ratio was taken to represent the polarization balance. There were no differences in traditional classical (CD14(++)CD16(-)), intermediate (CD14(++)CD16(+)) and nonclassical (CD14(+)CD16(+)) monocytes between groups. Rather, compared to NGT, pre-diabetic subjects showed a significant increase in pro-inflammatory M1 cells and percent expression of the oxLDL scavenger receptor CD68, without changes in anti-inflammatory M2 cells. M1 levels and CD68 expression were directly correlated with HbA1c. We show for the first time that otherwise healthy pre-diabetic subjects have excess M1 inflammatory cells in peripheral blood, which may contribute to cardiovascular risk.

Cutting edge: CD4 T cells reactive to an islet amyloid polypeptide peptide accumulate in the pancreas and contribute to disease pathogenesis in nonobese diabetic mice.

We previously reported a peptide KS20 from islet amyloid polypeptide (IAPP) to be the target Ag for a highly diabetogenic CD4 T cell clone BDC-5.2.9. To track IAPP-reactive T cells in NOD mice and determine how they contribute to the pathogenesis of type 1 diabetes, we designed a new I-Ag7 tetramer with high affinity for BDC-5.2.9 that contains the peptide KS20. We found that significant numbers of KS20 tetramer(+) CD4 T cells can be detected in the pancreas of prediabetic and diabetic NOD mice. To verify pathogenicity of IAPP-reactive cells, we sorted KS20 tetramer(+) cells and cloned them from uncloned T cell lines isolated from spleen and lymph nodes of diabetic mice. We isolated a new KS20-reactive Th1 CD4 T cell clone that rapidly transfers diabetes. Our results suggest that IAPP triggers a broad autoimmune response by CD4 T cells in NOD mice.

An alternative role for Foxp3 as an effector T cell regulator controlled through CD40.

The BDC2.5 T cell clone is highly diabetogenic, but the transgenic mouse generated from that clone is surprisingly slow in diabetes development. Although defining pathogenic effector T cells in autoimmunity has been inconsistent, CD4(+) cells expressing the CD40 receptor (Th40 cells) are highly diabetogenic in NOD mice, and NOD.BDC2.5.TCR.Tg mice possess large numbers of these cells. Given the importance of CD40 for pathogenic T cell development, BDC2.5.CD40(-/-) mice were created. Regulatory T cells, CD4(+)CD25(hi)Foxp3(+), develop normally, but pathogenic effector cells are severely reduced in number. Th40 cells from diabetic BDC2.5 mice rapidly induce diabetes in NOD.scid recipients, but Th40 cells from prediabetic mice transfer diabetes very slowly. Demonstrating an important paradigm shift, effector Th40 cells from prediabetic mice are Foxp3(+). As mice age, moving to type 1 diabetes development, Th40 cells lose Foxp3. When Th40 cells that are Foxp3(+) are transferred to NOD.scid recipients, disease is delayed. Th40 cells that are Foxp3(-) rapidly transfer disease. Th40 cells from BDC2.5.CD40(-/-) mice do not transfer disease nor do they lose Foxp3 expression. Mechanistically, Foxp3(+) cells produce IL-17 but do not produce IFN-γ, whereas Foxp3(-) Th40 cells produce IFN-γ and IL-2. This poses a new consideration for the function of Foxp3, as directly impacting effector T cell function.

Postload hyperglycemia is associated with increased subclinical inflammation in patients with prediabetes.

BACKGROUND/AIMS: In this present study, we aimed: (i) To clarify if prediabetes is associated with subclinical inflammation independent of underlying obesity, and (ii) to evaluate the effect of postload glucose concentration on subclinical inflammation markers in a group of patients with elevated fasting glucose. MATERIAL AND METHODS: In a cohort of 165 patients with newly detected fasting hyperglycemia, according to 75 g oral glucose tolerance test (OGTT), subjects were classified either as newly diagnosed type 2 diabetes (diabetes group, n = 40), impaired fasting glucose (IFG) plus impaired glucose tolerance (IGT) (IFG/IGT group, n = 42) or IFG only (IFG group, n = 83). A control group (n = 47) consisted of age- and body mass index (BMI)-matched healthy subjects with a normal OGTT. Circulating concentrations of lipids, insulin, interleukin-6 (IL-6), interleukin-8 (IL-8) and high sensitive C-reactive protein (hsCRP) were measured. HOMA index was calculated. RESULTS: Subclinical inflammation markers were elevated in patients with diabetes and IFG/IGT compared to healthy controls and also IFG patients (diabetes vs. control: p < 0.05 for hsCRP, IL-8, and IL-6; IFG/IGT vs. control: p < 0.05 for hsCRP, and IL-6; diabetes vs. IFG: p < 0.05 for hsCRP, and IL-6; IFG/IGT vs. IFG: p < 0.05 for hsCRP, and IL-6). In multiple regression analysis, postload glucose concentration was independently associated with circulating hsCRP and IL-6 concentrations when the data was controlled for age, gender, BMI and lipid concentrations (p < 0.05 for hsCRP, and IL-6). CONCLUSION: Our results suggest that patients with prediabetes, independent of underlying obesity, have increased concentrations of subclinical inflammation which is mostly driven by postload glucose concentrations.