Influence of sphingolipid enzymes on blood glucose levels, development of diabetes, and involvement of pericytes.

AIMS: Sulfatide is a chaperone for insulin manufacturing in beta cells. Here we explore whether the blood glucose values normally could be associated with this sphingolipid and especially two of its building enzymes CERS2 and CERS6. Both T1D and T2D have low blood sulfatide levels, and insulin resistance on beta cells at clinical diagnosis. Furthermore, we examined islet pericytes for sulfatide, and beta-cell receptors for GLP-1, both of which are related to the insulin production. MATERIALS AND METHODS: We examined mRNA levels in islets from the DiViD and nPOD studies, performed genetic association analyses, and histologically investigated pericytes in the islets for sulfatide. RESULTS: Polymorphisms of the gene encoding the CERS6 enzyme responsible for synthesising dihydroceramide, a precursor to sulfatide, are associated with random blood glucose values in non-diabetic persons. This fits well with our finding of sulfatide in pericytes in the islets, which regulates the capillary blood flow in the islets of Langerhans, which is important for oxygen supply to insulin production. In the islets of newly diagnosed T1D patients, we observed low levels of GLP-1 receptors; this may explain the insulin resistance in their beta cells and their low insulin production. In T2D patients, we identified associated polymorphisms in both CERS2 and CERS6. CONCLUSIONS: Here, we describe several polymorphisms in sulfatide enzymes related to blood glucose levels and HbA1c in non-diabetic individuals. Islet pericytes from such persons contain sulfatide. Furthermore, low insulin secretion in newly diagnosed T1D may be explained by beta-cell insulin resistance due to low levels of GLP-1 receptors.

Type 1 diabetes could begin with alterations in innate anti-viral immunity, which are already at this stage associated with HLA risk haplotypes.

AIMS: To investigate if HLA risk haplotypes and HbA1c levels are associated with the expression levels of innate anti-viral immune pathway genes in type 1 diabetes. MATERIALS AND METHODS: We investigated RNA expression levels of innate anti-viral immune pathway genes in laser-dissected islets from two to five tissue sections per donor from the Diabetes Virus Detection study and the network of Pancreatic Organ Donors in relation to HLA risk haplotypes (non-predisposed and predisposed) and HbA1c levels (normal, elevated, and high). RESULTS: The expression of innate anti-viral immune genes (TLR7, OAS1, OAS3 etc.) was significantly increased in individuals with predisposing vs non-predisposing HLA haplotypes. Also, the expression of several of the innate anti-viral immune genes from the HLA risk haplotype analysis was significantly increased in the group with high vs normal HbA1c. Furthermore, the gene expression of OAS2 was significantly increased in the group with high HbA1c vs elevated HbA1c. CONCLUSIONS: Expression of innate anti-viral immune pathway genes was increased in individuals with predisposing HLA risk haplotypes and those with high HbA1c. This indicates that type 1 diabetes might well begin with alterations in innate anti-viral immunity, and already at this stage be associated with HLA risk haplotypes.

Sulfatide inhibits fibroblast growth, activation and oxidative stress induced by ectopic insulin.

AIM: To study the effect of sulfatide on gene expression and proliferation of human primary fibroblasts induced by insulin, insulin-like growth factor-1 and human growth hormone. MATERIALS AND METHODS: Human primary fibroblasts were exposed to 1, 3 and 30 µM of sulfatide or its precursor galactosylceramide (GalCer). Proliferation was determined by 3 H-thymidine incorporation and gene expression via microarray analysis. RESULTS: Sulfatide and GalCer reduced the growth rate of fibroblasts by 32%-82% when exposed to 0.5 nM insulin. After challenge with 120 µM of H2 O2 , sulfatide reduced membrane leakage. Fibroblast gene expression was altered by sulfatide in gene pathways associated with cell cycle/growth, transforming growth factor-ß function, and encoding of proteins involved in intracellular signalling. NFKBIA, a key control element in NF-кB regulation, was decreased 2-fold by sulfatide. CONCLUSIONS: Sulfatide strongly inhibits fibroblast growth. We therefore suggest the addition of sulfatide to injectable commercial insulin formulations, which would reduce adverse fibroblast growth and improve well-being in patients with diabetes.

Gluten-free diet reduces autoimmune diabetes mellitus in mice across multiple generations in a microbiota-independent manner.

Experimental and clinical data suggest that a gluten-free diet attenuates the development of type 1 diabetes. A gluten-free diet changes the gut microbiota composition, and such microbial changes are expected to reduce the autoimmune responses. However, in experiments with laboratory mice, a gluten-free diet changes the gut microbiota differently under varying experimental settings, questioning the specific role of the gut microbes. Here we show that a maternal gluten-free diet until weaning of their pups, delayed type 1 diabetes in both dams (parent generation) and offspring (F1 generation) of untreated non-obese diabetic (NOD) mice and in mice treated with a full cocktail of antibiotics that eradicates most of the existing microbiota. Breeding a second (F2) generation of NOD mice, never exposed to the gluten-free diet or the associated microbial changes, also demonstrated a preventative effect on type 1 diabetes even though their parents (the F1 generation) had only been on a gluten-free diet very early in life. Collectively, the experimental data, thus, points towards microbiota-independent dietary protection. Furthermore, both the perinatal gluten-free diet and antibiotic treatment reduced inflammation in the salivary glands and improved glucose challenged beta cell function in the F1 offspring. However, in contrast to the autoimmune response in the pancreas, those changes appeared to be microbiota dependent, as they were missing in the antibiotic treated mice, and do, therefore, not seem to be related to the preventative effect on type 1 diabetes. Interestingly, adoptive transfer of splenocytes from gluten-free fed mice protected NOD.SCID mice from developing diabetes, demonstrating that the anti-diabetic effect of a gluten-free diet was based on early life changes in the evolving immune system. In particular, genes involved in regulation of lymphocyte activation, proliferation, and cell adhesion were highly expressed in the spleen in gluten-free fed mice at weaning compared to control fed mice of the F1 generation, which suggested that gluten promotes autoimmunity by inhibiting immune regulation, though the involvement of the specific genes needs further investigation. In conclusion, gluten-free diet reduces autoimmune inflammation in salivary glands and pancreas in NOD mice in a microbiota-dependent and -independent manner respectively, and has preventative effect on type 1 diabetes by modulating the systemic immune system.

Gluten-free diet modulates inflammation in salivary glands and pancreatic islets.

OBJECTIVES: A lifelong gluten-free (GF) diet ameliorates autoimmune diabetes in non-obese diabetic (NOD) mice and most likely in humans. Besides diabetes, NOD mice develop focal sialadenitis, as seen in Sjögren's syndrome (SS). In humans, type 1 diabetes (T1D) is also linked to SS. Here, we investigated whether a lifelong GF diet influences the immune cell infiltration in the salivary glands and pancreatic islets in NOD mice. METHODS: NOD mice were fed a lifelong (i.e. 13 weeks) GF or gluten-containing standard (STD) diet. Insulitis and sialadenitis were scored on H&E-stained paraffin-embedded sections of pancreas and submandibular glands. Immune cell specificity and distribution were investigated immunohistochemically. RESULTS: There were fewer CD68+ and CD4+ cells in submandibular gland areas with focal sialadenitis as well as reduced insulitis and fewer VEGFR2+ cells in pancreatic islets in mice on GF versus STD diet. The degree of sialadenitis was not significantly lower in GF mice, but sialadenitis and insulitis correlated strongly. Lung weight was lower in GF mice. CONCLUSION: In NOD mice, a lifelong GF diet reduces infiltration of monocytes/macrophages and T cells in salivary glands and inflammation in pancreatic islets, possibly by reducing VEGFR2, indicating that the linked autoimmune diseases, T1D and SS, may be alleviated by a GF diet.

Genetic predisposition in the 2'-5'A pathway in the development of type 1 diabetes: potential contribution to dysregulation of innate antiviral immunity.

AIMS/HYPOTHESIS: The incidence of type 1 diabetes is increasing more rapidly than can be explained by genetic drift. Viruses may play an important role in the disease, as they seem to activate the 2'-5'-linked oligoadenylate (2'-5'A) pathway of the innate antiviral immune system. Our aim was to investigate this possibility. METHODS: Innate antiviral immune pathways were searched for type 1 diabetes-associated polymorphisms using genome-wide association study data. SNPs within ±250kb flanking regions of the transcription start site of 64 genes were examined. These pathways were also investigated for type 1 diabetes-associated RNA expression profiles using laser-dissected islets from two to five tissue sections per donor from the Diabetes Virus Detection (DiViD) study and the network of Pancreatic Organ Donors (nPOD). RESULTS: We found 27 novel SNPs in genes nominally associated with type 1 diabetes. Three of those SNPs were located upstream of the 2'-5'A pathway, namely SNP rs4767000 (p = 1.03 × 10-9, OR 1.123), rs1034687 (p = 2.16 × 10-7, OR 0.869) and rs739744 (p = 1.03 × 10-9, OR 1.123). We also identified a large group of dysregulated islet genes in relation to type 1 diabetes, of which two were novel. The most aberrant genes were a group of IFN-stimulated genes. Of those, the following distinct pathways were targeted by the dysregulation (compared with the non-diabetic control group): OAS1 increased by 111% (p < 1.00 × 10-4, 95% CI -0.43, -0.15); MX1 increased by 142% (p < 1.00 × 10-4, 95% CI -0.52, -0.22); and ISG15 increased by 197% (p = 2.00 × 10-4, 95% CI -0.68, -0.18). CONCLUSIONS/INTERPRETATION: We identified a genetic predisposition in the 2'-5'A pathway that potentially contributes to dysregulation of the innate antiviral immune system in type 1 diabetes. This study describes a potential role for the 2'-5'A pathway and other components of the innate antiviral immune system in beta cell autoimmunity.

Intestinal permeability in type 1 diabetes: An updated comprehensive overview.

The etiopathogenesis of the autoimmune disease type 1 diabetes (T1D) is still largely unknown, however, both genetic and environmental factors contribute to the development of the disease. A major contact surface for environmental factors is the gastrointestinal (GI) tract, where barrier defects in T1D likely cause diabetogenic antigens to enter the body tissues, contributing to beta-cell autoimmunity. Human and animal research imply that increased intestinal permeability is an important disease determinant, although the underlying methodologies, interpretations and conclusions are diverse. In this review, an updated comprehensive overview on intestinal permeability in patients with T1D and animal models of T1D is provided in the categories: in vivo permeability, ex vivo permeability, zonulin, molecular permeability and blood markers. Across categories, there is consistency pointing towards increased intestinal permeability in T1D. In animal models of T1D, the intestinal permeability varies with age and strains implying a need for careful selection of method and experimental setup. Furthermore, dietary interventions that affect diabetes incidence in animal models does also impact the intestinal permeability, suggesting an association between increased intestinal permeability and T1D development.

Antibiotic treatment during early childhood and risk of type 1 diabetes in children: A national birth cohort study.

OBJECTIVE/BACKGROUND: Antibiotics are widely used during childhood infections and influence the composition of the microbiota, which is established during the first years of life. Evidence from animal models of type 1 diabetes shows that antibiotics might accelerate disease progression, and altered intestinal microbiota has been reported in association with type 1 diabetes in humans. We aimed to test the hypothesis that early exposure to antibiotics (0-24 months of age) was associated with an increased risk of childhood type 1 diabetes development. METHODS: We studied 75 615 mother-child dyads from the Danish National Birth Cohort. Information on the use of antibiotics during early childhood and type 1 diabetes development in childhood was available for all children via linkage to the Danish National Prescription Registry and the Danish National Patient Register, respectively. The mean follow-up time was 14.3 years (range 11.5 to 18.4 years, SD 1.4). RESULTS: After adjustment for confounders, we found no association between antibiotic exposure and risk of type 1 diabetes (HR 1.26, 95% CI 0.89-1.79). The number of antibiotic courses during early childhood was not associated with type 1 diabetes development when analyzing for one (HR 1.31, 95% CI 0.87-1.99), two (HR 0.99, 95% CI 0.61-1.63), or 3 or more (HR 1.42, 95% CI 0.95-2.11) courses. Furthermore, no specific types of antibiotics (penicillins/beta-lactam antibacterials, sulfonamide/trimethroprim, or macrolides/lincosamides/streptogramins) were associated with increased risk of type 1 diabetes. CONCLUSION: Our nationwide cohort study suggests that postnatal exposure to antibiotics does not influence the development of childhood type 1 diabetes.

Fenofibrate increases very-long-chain sphingolipids and improves blood glucose homeostasis in NOD mice.

AIMS/HYPOTHESIS: Sphingolipid metabolism regulates beta cell biology and inflammation and is abnormal at the onset of type 1 diabetes. Fenofibrate, a regulator of sphingolipid metabolism, is known to prevent diabetes in NOD mice. Here, we aimed to investigate the effects of fenofibrate on the pancreatic lipidome, pancreas morphology, pancreatic sympathetic nerves and blood glucose homeostasis in NOD mice. METHODS: We treated female NOD mice with fenofibrate from 3 weeks of age. The pancreatic lipidome was analysed using MS. Analysis of pancreas and islet volume was performed by stereology. Islet sympathetic nerve fibre volume was evaluated using tyrosine hydroxylase staining. The effect on blood glucose homeostasis was assessed by measuring non-fasting blood glucose from age 12 to 30 weeks. Furthermore, we measured glucose tolerance, fasting insulin and glucagon levels, and insulin tolerance. RESULTS: We found that fenofibrate selectively increases the amount of very-long-chain sphingolipids in the pancreas of NOD mice. In addition, we found that fenofibrate causes a remodelling of the pancreatic lipidome with an increased amount of lysoglycerophospholipids. Fenofibrate did not affect islet or pancreas volume, but led to a higher volume of islet sympathetic nerve fibres and tyrosine hydroxylase-positive cells. Fenofibrate-treated NOD mice had a more stable blood glucose, which was associated with reduced non-fasting and increased fasting blood glucose. Furthermore, fenofibrate improved glucose tolerance, reduced fasting glucagon levels and prevented fasting hyperinsulinaemia. CONCLUSIONS/INTERPRETATION: These data indicate that fenofibrate alters the pancreatic lipidome to a more anti-inflammatory and anti-apoptotic state. The beneficial effects on islet sympathetic nerve fibres and blood glucose homeostasis indicate that fenofibrate could be used as a therapeutic approach to improve blood glucose homeostasis and prevent diabetes-associated pathologies.

Tolerogenic Dendritic Cells from Poorly Compensated Type 1 Diabetes Patients Have Decreased Ability To Induce Stable Antigen-Specific T Cell Hyporesponsiveness and Generation of Suppressive Regulatory T Cells.

Tolerogenic dendritic cells (tolDCs) may offer an interesting intervention strategy to re-establish Ag-specific tolerance in autoimmune diseases, including type 1 diabetes (T1D). T1D results from selective destruction of insulin-producing ß cells leading to hyperglycemia that, in turn, specifically affects a patient's immune system. In this study, we prepared monocyte-derived tolDCs modulated by dexamethasone and vitamin D2 from 31 T1D patients with optimal glycemic control and 60 T1D patients with suboptimal glycemic control and assessed their tolerogenic properties in correlation with metabolic state of patients. tolDCs differentiated from both groups of patients acquired a regulatory phenotype and an anti-inflammatory profile. Interestingly, tolDCs from well-controlled patients expressed higher levels of inhibitory molecules IL-T3 and PD-L1. Additionally, glutamic acid decarboxylase (GAD)65-loaded tolDCs from well-controlled patients decreased significantly primary Th1/Th17 responses, induced stable GAD65-specific T cell hyporesponsiveness, and suppressed markedly control DC-induced GAD65-specific T cell activation compared with poorly controlled patients. The ability of tolDCs from poorly controlled patients to induce durable GAD65-specific T cell hyporesponsiveness was reversed once the control of glycemia improved. In both groups of patients, tolDCs were able to induce regulatory T cells from autologous naive CD4+ T cells. However, regulatory T cells from well-controlled patients had better suppressive abilities. The functionality of tolDCs was confirmed in the adoptive transfer model of NOD-SCID mice where tolDCs delayed diabetes onset. These results suggest that metabolic control of T1D affects the functional characteristics of tolDCs and subsequent effector T cell responses. Metabolic control may be relevant for refining inclusion criteria of clinical trials in the settings of T1D.

Abnormal islet sphingolipid metabolism in type 1 diabetes.

AIMS/HYPOTHESIS: Sphingolipids play important roles in beta cell physiology, by regulating proinsulin folding and insulin secretion and in controlling apoptosis, as studied in animal models and cell cultures. Here we investigate whether sphingolipid metabolism may contribute to the pathogenesis of human type 1 diabetes and whether increasing the levels of the sphingolipid sulfatide would prevent models of diabetes in NOD mice. METHODS: We examined the amount and distribution of sulfatide in human pancreatic islets by immunohistochemistry, immunofluorescence and electron microscopy. Transcriptional analysis was used to evaluate expression of sphingolipid-related genes in isolated human islets. Genome-wide association studies (GWAS) and a T cell proliferation assay were used to identify type 1 diabetes related polymorphisms and test how these affect cellular islet autoimmunity. Finally, we treated NOD mice with fenofibrate, a known activator of sulfatide biosynthesis, to evaluate the effect on experimental autoimmune diabetes development. RESULTS: We found reduced amounts of sulfatide, 23% of the levels in control participants, in pancreatic islets of individuals with newly diagnosed type 1 diabetes, which were associated with reduced expression of enzymes involved in sphingolipid metabolism. Next, we discovered eight gene polymorphisms (ORMDL3, SPHK2, B4GALNT1, SLC1A5, GALC, PPARD, PPARG and B4GALT1) involved in sphingolipid metabolism that contribute to the genetic predisposition to type 1 diabetes. These gene polymorphisms correlated with the degree of cellular islet autoimmunity in a cohort of individuals with type 1 diabetes. Finally, using fenofibrate, which activates sulfatide biosynthesis, we completely prevented diabetes in NOD mice and even reversed the disease in half of otherwise diabetic animals. CONCLUSIONS/INTERPRETATION: These results indicate that islet sphingolipid metabolism is abnormal in type 1 diabetes and suggest that modulation may represent a novel therapeutic approach. DATA AVAILABILITY: The RNA expression data is available online at https://www.dropbox.com/s/93mk5tzl5fdyo6b/Abnormal%20islet%20sphingolipid%20metabolism%20in%20type%201%20diabetes%2C%20RNA%20expression.xlsx?dl=0 . A list of SNPs identified is available at https://www.dropbox.com/s/yfojma9xanpp2ju/Abnormal%20islet%20sphingolipid%20metabolism%20in%20type%201%20diabetes%20SNP.xlsx?dl=0 .

Gluten-free diet during pregnancy alleviates signs of diabetes and celiac disease in NOD mouse offspring.

BACKGROUND: Gluten-free (GF) diet during pregnancy ameliorates autoimmune diabetes in nonobese diabetic (NOD) mouse offspring. Due to comorbidity of celiac disease in type 1 diabetes, we hypothesized that GF diet in utero alleviates the humoral and histopathological signs of celiac disease in NOD mice. We aimed to establish the mechanisms behind the diabetes-protective effect of GF diet in utero. METHODS: Breeding pairs of NOD mice were fed a GF or gluten-containing standard (STD) diet until parturition. The offspring were nursed by mothers on STD diet and continued on this diet until ages 4 and 13 weeks. Analyses of serum antitissue transglutaminase (anti-tTG) intestine and islet histology, islet transglutaminase (TG) activity, and cytokine expression in T cells from lymphoid organs were performed. RESULTS: GF versus STD diet in utero led to reduced serum anti-tTG titre and increased villus-to-crypt ratio at both ages. Insulitis along with systemic and local inflammation were decreased, but islet TG activity was unchanged in 13-week-old GF mice. These mice had unchanged beta-cell volumes, but increased islet numbers throughout the prediabetic period. CONCLUSIONS: Collectively, GF diet administered during pregnancy improves signs of celiac disease and autoimmune diabetes in the offspring. The diabetes-ameliorative effect of GF diet in utero is followed by dampening of inflammation, unchanged beta-cell volume, but increased islet numbers.

Oral insulin does not alter gut microbiota composition of NOD mice.

BACKGROUND: Oral insulin as a preventive strategy and/or treatment of type 1 diabetes has been the target of much research. Producing oral insulins is a complex and challenging task, with numerous pitfalls, due to physiological, physical, and biochemical barriers. Our aim was to determine the impact of oral insulin on the delicate gut microbiota composition. METHODS: Female nonobese diabetic mice were given oral porcine insulin 2 times a week from 5 weeks of age for 4 weeks, and then subsequently once a week for 21 weeks, or until euthanized. The mice were divided into groups on a gluten-reduced diet or a standard diet. Gut microbiota composition was analysed based on faecal samples, and the type 1 diabetes incidence of the mice was monitored. RESULTS: We observed no influence of the oral porcine insulin on the gut microbiota composition of mice on a gluten-reduced or a standard diet at 9 weeks of age. Also, the administration of oral insulin did not influence the incidence of type 1 diabetes at 30 weeks of age. CONCLUSIONS: Oral porcine insulin does not alter the gut microbiota composition of nonobese diabetic mice on either a gluten-reduced diet or standard diet. Also, the oral porcine insulin did not influence the incidence of type 1 diabetes in the groups.

Childhood body mass index in relation to subsequent risk of type 1 diabetes-A Danish cohort study.

The incidence of type 1 diabetes (T1D) is increasing, and obesity may be a contributing factor by increasing the risk and accelerating the onset. We investigated the relation between childhood body mass index z-scores (BMIz) and the later risk of T1D, including association with age at onset of T1D. The study included 238 cases and 10 147 controls selected from the Copenhagen School Health Record Register (CSHRR). Cases of T1D were identified in the Danish Registry of Childhood and Adolescent Diabetes and 2 regional studies and linked to CSHRR. Using conditional logistic regression models, the association of childhood prediagnostic BMIz at 7 and 13 years of age and changes between these ages with subsequent risk (odds ratio, OR) of T1D was estimated. A greater BMIz at 7 and 13 years of age was associated with increased risk of T1D with OR of 1.23 (confidence interval, CI 1.09-1.37; P = .0001) and 1.20 (CI 1.04-1.40; P = .016), respectively. The risk was increased by upward changes in z-scores from birth to 7 years (OR=1.21, P = .003) and from 7 to 13 years of age (OR=1.95, P = .023), but in the latter age interval also by a decline in BMIz (OR = 1.91, P = .034). There were no associations between BMIz at 7 and 13 years of age and the age of onset (P = .34 and P = .42, respectively). Increased BMIz is associated with a moderate increase in risk of T1D, but with no relation to age at onset within the analyzed age range. Increased BMIz over time is unlikely to explain the rising incidence of T1D.

Diabetes, diabetes treatment, and mammographic density in Danish Diet, Cancer, and Health cohort.

PURPOSE: We examined whether diabetes and diabetes treatment are associated with MD in a cohort study of Danish women above age of 50 years. METHODS: Study cohort consisted of 5,644 women (4,500 postmenopausal) who participated in the Danish Diet, Cancer, and Health cohort (1993-1997) and subsequently attended mammographic screening in Copenhagen (1993-2001). We used MD assessed at the first screening after the cohort entry, defined as mixed/dense or fatty. Diabetes diagnoses and diabetes treatments (diet, insulin, or oral antidiabetic agents) were self-reported at the time of recruitment (1993-1997). The association between MD and diabetes was analyzed by logistic regression adjusted for potential confounders. Effect modification by menopausal status and body mass index (BMI) was performed by introducing an interaction term into the model and tested by Wald test. RESULTS: Of 5,644 women with mean age of 56 years, 137 (2.4%) had diabetes and 3,180 (56.3%) had mixed/dense breasts. Having diabetes was significantly inversely associated with having mixed/dense breasts, in both, the crude model (odds ratio; 95% confidence interval: 0.33; 0.23-0.48), and after adjustment for adiposity and other risk factors (0.61; 0.40-0.92). Similar inverse associations were observed for 44 women who controlled diabetes by diet only and did not receive any medication (0.56; 0.27-1.14), and 62 who took oral antidiabetic agents only for diabetes (0.59; 0.32-1.09), while women taking insulin had increased odds of mixed/dense breasts (2.08; 0.68-6.35). There was no effect modification of these associations by menopausal status or BMI. CONCLUSIONS: Having diabetes controlled by diet or oral antidiabetic agents is associated with a decrease in MD, whereas taking insulin is associated with an increase in MD.

Gluten-free diet increases beta-cell volume and improves glucose tolerance in an animal model of type 2 diabetes.

BACKGROUND: Gluten-free (GF) diet alleviates type 1 diabetes in animal models and possibly in humans. We recently showed that fatty acid-induced insulin secretion is enhanced by enzymatically digested gluten (gliadin) stimulation in INS-1E insulinoma cells. We therefore hypothesized that GF diet would induce beta-cell rest and ameliorate type 2 diabetes. METHODS: C57BL/6JBomTac (B6) mice were fed a high-fat (HF), gluten-free high-fat (GF-HF), standard (STD) or gluten-free (GF) diet for 42 weeks. RESULTS: Short-term (6-24 weeks) GF-HF versus HF feeding impaired glucose tolerance and increased fasting glucose. Long-term (36-42 weeks) GF-HF versus HF feeding improved glucose tolerance and decreased fasting leptin. Mice fed a GF-HF versus HF diet for 42 weeks showed higher volumes of beta cells, islets and pancreas. The beta-cell volume correlated with the islet- and pancreas volume as well as body weight. GF-HF versus HF diet did not influence toll-like receptor 4 (Tlr4), interleukin 1 (IL-1), interleukin 6 (IL-6) or tumour necrosis factor-alpha (TNF-alpha) mRNA expression in intestine. STD versus GF feeding did not affect any parameter studied. CONCLUSIONS: Long-term feeding with GF-HF versus HF increases beta-cell volume and improves glucose tolerance in B6 mice. The mechanism may include beta-cell rest, but is unlikely to include TLR4 and proinflammatory cytokines in the intestine. Beta-cell volume correlates with pancreas volume and body weight, indicating that insulin secretion capacity controls pancreas volume. Thus, long-term GF diets may be beneficial for obese type 2 diabetes patients and trials should be performed. Copyright © 2016 John Wiley & Sons, Ltd.

Mode of delivery shapes gut colonization pattern and modulates regulatory immunity in mice.

Delivery mode has been associated with long-term changes in gut microbiota composition and more recently also with changes in the immune system. This has further been suggested to link Cesarean section (C-section) with an increased risk for development of immune-mediated diseases such as type 1 diabetes. In this study, we demonstrate that both C-section and cross-fostering with a genetically distinct strain influence the gut microbiota composition and immune key markers in mice. Gut microbiota profiling by denaturing gradient gel electrophoresis and 454/FLX-based 16S rRNA gene amplicon sequencing revealed that mice born by C-section had a distinct bacterial profile at weaning characterized by higher abundance of Bacteroides and Lachnospiraceae, and less Rikenellaceae and Ruminococcus. No clustering according to delivery method as determined by principal component analysis of denaturing gradient gel electrophoresis profiles was evident in adult mice. However, the adult C-section-born mice had lower proportions of Foxp3(+) regulatory T cells, tolerogenic CD103(+) dendritic cells, and less Il10 gene expression in mesenteric lymph nodes and spleens. This demonstrates long-term systemic effect on the regulatory immune system that was also evident in NOD mice, a model of type 1 diabetes, born by C-section. However, no effect of delivery mode was seen on diabetes incidence or insulitis development. In conclusion, the first exposure to microorganisms seems to be crucial for the early life gut microbiota and priming of regulatory immune system in mice, and mode of delivery strongly influences this.

Dietary gluten increases natural killer cell cytotoxicity and cytokine secretion.

Dietary gluten influences the development of type 1 diabetes in nonobese diabetic (NOD) mice and biobreeding rats, and has been shown to influence a wide range of immunological factors in the pancreas and gut. In the present study, the effects of gluten on NK cells were studied in vitro and in vivo. We demonstrated that gliadin increased direct cytotoxicity and IFN-γ secretion from murine splenocytes and NK cells toward the pancreatic beta-cell line MIN6 cells. Additionally, stimulation of MIN6 cells led to a significantly increased proportion of degranulating C57BL/6 CD107a(+) NK cells. Stimulation of C57BL/6 pancreatic islets with gliadin significantly increased secretion of IL-6 more than ninefold. In vivo, the gluten-containing diet led to a higher expression of NKG2D and CD71 on NKp46(+) cells in all lymphoid organs in BALB/c and NOD mice compared with the gluten-free diet. Collectively, our data suggest that dietary gluten increases murine NK-cell activity against pancreatic beta cells. This mechanism may contribute to development of type 1 diabetes and explain the higher disease incidence associated with gluten intake in NOD mice.

CD1d knockout mice exhibit aggravated contact hypersensitivity responses due to reduced interleukin-10 production predominantly by regulatory B cells.

Conflicting observations have been reported concerning the role of CD1d-dependent natural killer T (NKT) cells in contact hypersensitivity (CHS), supporting either a disease-promoting or downregulatory function. We studied the role of NKT cells in CHS by comparing the immune response in CD1d knockout (CD1d KO) and wild-type (Wt) mice after contact allergen exposure. For induction of CHS, C57BL/6 CD1d KO mice (n = 6) and C57BL/6 Wt mice (n = 6) were sensitised with 1% (w/v) dinitrochlorobenzene (DNCB) or vehicle for three consecutive days and subsequently challenged with a single dose of 0.5% DNCB (w/v) on the ears fifteen days later. We demonstrate that CD1d KO mice, as compared with Wt littermates, have more pronounced infiltration of mononuclear cells in the skin (29.1% increase; P < 0.001), lower frequencies of interleukin-10(+) B cells (B(regs) ) in the spleen (53.2% decrease; P < 0.05) and peritoneal cavity (80.8% decrease; P < 0.05) and increased production of interferon-γ (3-fold; P < 0.05) after DNCB sensitisation and challenge, which suggests an important regulatory and protective role of CD1d-dependent NKT cells in CHS in our model, at least in part via regulation of IL-10 producing B(regs) .

Prevalence of celiac disease autoimmunity in children with type 1 diabetes: regional variations across the Øresund strait between Denmark and southernmost Sweden.

OBJECTIVES: The aim was to determine the prevalence of celiac disease autoimmunity in children with type 1 diabetes (T1D) diagnosed in Denmark and Sweden. METHODS: A total of 662 Swedish children with T1D were matched with 1080 Danish children with T1D and 309 healthy children from Sweden and 283 from Denmark served as controls. Sera were analyzed for the presence of IgA and IgG (IgAG) autoantibodies against deamidated gliadin peptide (DGP) and tissue transglutaminase (tTG) with enzyme-linked immunosorbent assay (ELISA) and IgG-tTG separately in a radioligand binding assay (RBA). Human leukocyte antigen (HLA)-DQB1 and DQA1 genotyping were determined in the T1D cohorts. RESULTS: In the Swedish T1D cohort, 17.2% (114/662) were IgAG-DGP/tTG positive compared with 11.7% (126/1080) in the Danish T1D cohort (p = 0.001) and with 9.4% (29/309) Swedish (p = 0.001) and 5.7% (16/283) Danish (p = 0.003) controls. In the Swedish T1D cohort, both levels of IgAG-DGP/tTG and IgG-tTG were higher compared with the levels in the Danish T1D (p < 0.001). In the control group, 2.8% of the Danish children were positive for both IgAG-DGP/tTG and IgG-tTG, compared to 0.3% of the Swedish. Presence of HLA-DQ2 was equally distributed among 89 children with T1D positive for both IgAG-DGP/tTG and IgG-tTG. CONCLUSION: The discrepancy in levels of IgAG-DGP/tTG and IgG-tTG between Swedish and Danish T1D cohorts was independent of HLA and suggests that regional variations in comorbidity of celiac disease in T1D is caused by difference in exposure to environmental factors.