Diabetes-specific HLA-DR-restricted proinflammatory T-cell response to wheat polypeptides in tissue transglutaminase antibody-negative patients with type 1 diabetes

Improvement in Mung Bean Peptide on High-Fat Diet-Induced Insulin Resistance Mice Using Untargeted Serum Metabolomics

This study aimed to elucidate the potential regulatory mechanism of mung bean peptides (MBPs) on glucolipid metabolism in insulin-resistant mice induced by high-fat diet (HFD) using untargeted serum metabolomics, enzyme linked immunosorbent assay (ELISA), intraperitoneal injection glucose tolerance test (IPGTT), insulin tolerance test (IPITT), and hematoxylin-eosin staining (H&E). The regulatory effect of MBPs for alleviating insulin resistance was studied by measuring body weight, fasting blood glucose (FBG) and serum insulin levels, C-Peptide levels, inflammatory and antioxidant factors, and histopathological observation of C57BL/6 mice. The experimental results showed that dietary intervention with MBPs (245 mg/kg/d) for 5 weeks significantly relieved insulin resistance in HFD mice. The body weight, insulin resistance index, and the levels of FBG, C-Peptide, IL-6, TNF-α, and MDA in the serum of HFD mice significantly decreased (P < 0.05). Conversely, SOD content and pancreatic β cell function index significantly increased (P < 0.05), and the damaged pancreatic tissue was repaired. One biomarker associated with insulin resistance was glycine. In addition, there were four important differential metabolites: pyroglutamate, D-glutamine, aminoadipic acid, and nicotinamide, involved in 12 metabolic pathway changes. It was found that MBPs may regulate amino acid, glycerol phospholipid, fatty acid, alkaloid, and nicotinamide metabolism to regulate the metabolic profile of HFD mice in a beneficial direction.

Gluten Free Diet for the Management of Non Celiac Diseases: The Two Sides of the Coin

A lifelong adherence to a gluten-free (GF) diet is currently the only treatment for Celiac disease (CD), an autoimmune disorder that arises after gluten ingestion in individuals who are genetically predisposed. The gluten intake exerts toxic effects through several pathways involving gut barrier integrity, intestinal microbiota composition and immune system stimulation. However, despite the great benefit of GF diet for CD patients, its use has been debated. Indeed, individuals who adopt this diet regime may be at risk of nutrient deficiencies. Emerging evidence supports a beneficial effect of a GF diet also for other pathological conditions, including gluten-related disorders (GRD) often associated to CD, such as Non celiac gluten sensitivity (NCGS) and Dermatitis Herpetiforme (DH) as well as Irritable bowel syndrome (IBS) and Diabetes. This suggests a pathogenic role of gluten in these conditions. Despite the growing popularity of GF diet among consumers, to date, there are limited evidences supporting its use for the management of non-celiac diseases. Therefore, in this review, we discuss whether the GF diet could really improve the general quality of life of patients with GRD and non-GRD conditions, keeping in mind its sensorial limitations and nutritional inadequacies. In addition, we discuss the current motivations, leading to the use of a GF diet, despite the inferior quality of GF products respect to those containing gluten.

Wheat gluten intake increases the severity of experimental colitis and bacterial translocation by weakening of the proteins of the junctional complex

Gluten is only partially digested by intestinal enzymes and can generate peptides that can alter intestinal permeability, facilitating bacterial translocation, thus affecting the immune system. Few studies addressed the role of diet with gluten in the development of colitis. Therefore, we investigate the effects of wheat gluten-containing diet on the evolution of sodium dextran sulphate (DSS)-induced colitis. Mice were fed a standard diet without (colitis group) or with 4·5 % wheat gluten (colitis + gluten) for 15 d and received DSS solution (1·5 %, w/v) instead of water during the last 7 d. Compared with the colitis group, colitis + gluten mice presented a worse clinical score, a larger extension of colonic injury area, and increased mucosal inflammation. Both intestinal permeability and bacterial translocation were increased, propitiating bacteria migration for peripheral organs. The mechanism by which diet with gluten exacerbates colitis appears to be related to changes in protein production and organisation in adhesion junctions and desmosomes. The protein α-E-catenin was especially reduced in mice fed gluten, which compromised the localisation of E-cadherin and β-catenin proteins, weakening the structure of desmosomes. The epithelial damage caused by gluten included shortening of microvilli, a high number of digestive vacuoles, and changes in the endosome/lysosome system. In conclusion, our results show that wheat gluten-containing diet exacerbates the mucosal damage caused by colitis, reducing intestinal barrier function and increasing bacterial translocation. These effects are related to the induction of weakness and disorganisation of adhesion junctions and desmosomes as well as shortening of microvilli and modification of the endocytic vesicle route.

Gluten exacerbates atherosclerotic plaque formation in ApoE-/- mice with diet-induced obesity

OBJECTIVES

Atherosclerosis is an underlying cause of cardiovascular disease, and obesity is one of the risk factors for atherogenesis. Although a gluten-free diet (GFD) has gained popularity as a strategy for weight loss, little is known about the effects of gluten on obesity. We have previously shown a negative effect of gluten on obesity in mice. However, its effects on atherogenesis are still unknown. Therefore, the aim of this study was to determine the effects of gluten on atherosclerosis progression during obesity.

METHODS

Atherosclerosis-susceptible ApoE knockout mice were subjected to an obesogenic GFD or a diet with 4.5% gluten (GD) for 10 wk.

RESULTS

Results from the study found that food intake and lipid profile were similar between the groups. However, GD promoted an increase in weight gain, adiposity, and plasma glucose. Pro-inflammatory factors such as tumor necrosis factor, interleukin-6, chemokine ligand-2, and matrix metalloproteinase-2 and -9 also were increased in the adipose tissue of gluten-fed mice. This inflammatory profile was associated with reduced phosphorylation of Akt, and consequently with the intensification of insulin resistance. The GD-enhanced vascular inflammation contributed to the worsening of atherosclerosis in the aorta and aortic root. Inflammatory cells, such as monocyte/macrophage and natural killer cells, and oxidative stress markers, such as superoxide and nitrotyrosine, were increased in atherosclerotic lesions of the GD group. Furthermore, the lesions presented higher necrotic core and lower collagen content, characterizing the less stable plaques.

CONCLUSION

The gluten-containing high-fat diet was associated with a more severe proatherogenic profile than the gluten-free high-fat diet owing to increased inflammatory and oxidative status at atherosclerotic lesions in obese mice.

Serum Zonulin in HBV-Associated Chronic Hepatitis, Liver Cirrhosis, and Hepatocellular Carcinoma

Background

The gut microbiota is involved in the occurrence and development of chronic liver diseases. Zonulin is considered a marker of intestinal permeability. The purpose of this study was to assess zonulin levels in patients with chronic hepatitis B (CHB), HBV-associated liver cirrhosis (LC), and HBV-associated hepatocellular carcinoma (HCC).

Materials and Methods

The study population consisted of 90 HBV-associated HCC patients, 90 HBV-associated LC patients, 90 CHB patients, and 90 healthy subjects. Serum levels of zonulin and AFP were determined. The diagnostic accuracy of each marker was evaluated using receiver operating characteristic (ROC) curve analysis (AUC).

Results

Serum zonulin levels were significantly higher in patients with HCC than in patients with LC or CHB or healthy subjects (p < 0.001). Moreover, the zonulin levels were increased in the advanced stage of LC and HCC. ROC curve analysis revealed that serum zonulin could be used to differentiate CHB from cirrhosis. In addition, the combination of zonulin and AFP exhibited a significantly larger AUC compared with zonulin or AFP alone.

Conclusions

Serum zonulin levels were significantly increased both in LC and in HCC and correlated with the advanced stage of LC and HCC. Moreover, the combination of zonulin and AFP confers significant benefit to diagnostic accuracy in differentiating LC from HCC.

Possible Prevention of Diabetes with a Gluten-Free Diet

Gluten seems a potentially important determinant in type 1 diabetes (T1D) and type 2 diabetes (T2D). Intake of gluten, a major component of wheat, rye, and barley, affects the microbiota and increases the intestinal permeability. Moreover, studies have demonstrated that gluten peptides, after crossing the intestinal barrier, lead to a more inflammatory milieu. Gluten peptides enter the pancreas where they affect the morphology and might induce beta-cell stress by enhancing glucose- and palmitate-stimulated insulin secretion. Interestingly, animal studies and a human study have demonstrated that a gluten-free (GF) diet during pregnancy reduces the risk of T1D. Evidence regarding the role of a GF diet in T2D is less clear. Some studies have linked intake of a GF diet to reduced obesity and T2D and suggested a role in reducing leptin- and insulin-resistance and increasing beta-cell volume. The current knowledge indicates that gluten, among many environmental factors, may be an aetiopathogenic factors for development of T1D and T2D. However, human intervention trials are needed to confirm this and the proposed mechanisms.

Changes in insulin, glucagon and ER stress precede immune activation in type 1 diabetes

It is unknown whether there is a gene signature in pancreas which is associated with type 1 diabetes (T1D). We performed partial pancreatectomies on 30-day preinsulitic, diabetes-prone BioBreeding (BBdp) rats to prospectively identify factors involved in early prediabetes. Microarrays of the biopsies revealed downregulation of endoplasmic reticulum (ER) stress, metabolism and apoptosis. Based on these results, additional investigations compared gene expression in control (BBc) and BBdp rats age ~8, 30 and 60 days using RT-qPCR. Neonates had increased ER stress gene expression in pancreas. This was associated with decreased insulin, cleaved caspase-3 and Ins1 whereas Gcg and Pcsk2 were increased. The increase in ER stress was not sustained at 30 days and decreased by 60 days. In parallel, the liver gene profile showed a similar signature in neonates but with an early decrease of the unfolded protein response (UPR) at 30 days. This suggested that changes in the liver precede those in the pancreas. Tnf and Il1b expression was increased in BBdp pancreas in association with increased caspase-1, cleaved caspase-3 and decreased proinsulin area. Glucagon area was increased in both 30-day and 60-day BBdp rats. Increased colocalization of BIP and proinsulin was observed at 60 days in the pancreas, suggesting insulin-related ER dysfunction. We propose that dysregulated metabolism leads to ER stress in neonatal rats long before insulitis, creating a microenvironment in both pancreas and liver that promotes autoimmunity.

Gut microbiome and type 2 diabetes: where we are and where to go?

Type 2 diabetes mellitus (T2D) is a highly prevalent metabolic disorder characterized by an imbalance in blood glucose level, altered lipid profile and high blood pressure. Genetic constituents, high-fat and high-energy dietary habits, and a sedentary lifestyle are three major factors that contribute to high risk of T2D. Several studies have reported gut microbiome dysbiosis as a factor in rapid progression of insulin resistance in T2D that accounts for about 90% of all diabetes cases worldwide. The gut microbiome dysbiosis may reshape intestinal barrier functions and host metabolic and signaling pathways, which are directly or indirectly related to the insulin resistance in T2D. Thousands of the metabolites derived from microbes interact with the epithelial, hepatic and cardiac cell receptors that modulate host physiology. Xenobiotics including dietary components, antibiotics and nonsteroidal anti-inflammatory drugs strongly affect the gut microbial composition and can promote dysbiosis. Any change in the gut microbiota can shift the host metabolism towards increased energy harvest during diabetes and obesity. However, the exact mechanisms behind the dynamics of gut microbes and their impact on host metabolism at the molecular level are yet to be deciphered. We reviewed the published literature for better understanding of the dynamics of gut microbiota, factors that potentially induce gut microbiome dysbiosis and their relation to the progression of T2D. Special emphasis was also given to understand the gut microbiome induced breaching of intestinal barriers and/or tight junctions and their relation to insulin resistance.

Plasmodium vivax Pv12 B-cell epitopes and HLA-DRβ1*-dependent T-cell epitopes in vitro antigenicity

Malaria is an infectious disease caused by parasites from the genus Plasmodium (P. falciparum and P. vivax are responsible for 90% of all clinical cases); it is widely distributed throughout the world’s tropical and subtropical regions. The P. vivax Pv12 protein is involved in invasion, is expressed on merozoite surface and has been recognised by antibodies from individuals exposed to the disease. In this study, B- and T-cell epitopes from Pv12 were predicted and characterised to advance in the design of a peptide-based vaccine against malaria.

For evaluating the humoral response of individuals exposed to natural P. vivax infection from two endemic areas in Colombia, BepiPred-1.0 software was used for selecting B-cell epitopes. B-cell epitope 39038 displayed the greatest recognition by naturally-acquired antibodies and induced an IgG2/IgG4 response. NetMHCIIpan-3.1 prediction software was used for selecting peptides having high affinity binding for HLA-DRβ1* allele lineages and this was confirmed by in-vitro binding assays. T-epitopes 39113 and 39117 triggered a memory T-cell response (Stimulation Index≥2) and significant cytokine production.

Combining in-silico, in-vitro and functional assays, two Pv12 protein regions (containing peptides 39038, 39040, 39113 and 39117) have thus been characterised as promising vaccine candidates against P. vivax malaria.

Type 1 Diabetes Mellitus: Cellular and Molecular Pathophysiology at A Glance

Type 1 diabetes mellitus (T1DM) is a disease where destruction of the insulin producing pancreatic beta-cells leads to increased blood sugar levels. Both genetic and environmental factors play a part in the development of T1DM. Currently, numerous loci are specified to be the responsible genetic factors for T1DM; however, the mechanisms of only a few of these genes are known. Although several environmental factors are presumed responsible for progression of T1DM, to date, most of their mechanisms remain undiscovered. After several years of hyperglycemia, late onsets of macrovascular (e.g., cardiovascular) and microvascular (e.g., neurological, ophthalmological, and renal) complications may occur. This review and accompanying figures provides an overview of the etiological factors for T1DM, its pathogenesis at the cellular level, and attributed complications.

Where genes meet environment-integrating the role of gut luminal contents, immunity and pancreas in type 1 diabetes

The rise in new cases of type 1 diabetes (T1D) in genetically susceptible individuals over the past half century has been attributed to numerous environmental "triggers" or promoters such as enteroviruses, diet, and most recently, gut bacteria. No single cause has been identified in humans, likely because there are several pathways by which one can develop T1D. There is renewed attention to the role of the gut and its immune system in T1D pathogenesis based largely on recent animal studies demonstrating that altering the gut microbiota affects diabetes incidence. Although T1D patients display dysbiosis in the gut microbiome, it is unclear whether this is cause or effect. The heart of this question involves several moving parts including numerous risk genes, diet, viruses, gut microbiota, timing, and loss of immune tolerance to β-cells. Most clinical trials have addressed only one aspect of this puzzle using some form of immune suppression, without much success. The key location where our genes meet and deal with the environment is the gastrointestinal tract. The influence of all of its major contents, including microbes, diet, and immune system, must be understood as part of the integrative biology of T1D before we can develop durable means of preventing, treating, or curing this disease. In the present review, we expand our previous gut-centric model based on recent developments in the field.

Cathelicidin Antimicrobial Peptide: A Novel Regulator of Islet Function, Islet Regeneration, and Selected Gut Bacteria

Cathelicidin antimicrobial peptide (CAMP) is a naturally occurring secreted peptide that is expressed in several organs with pleiotropic roles in immunomodulation, wound healing, and cell growth. We previously demonstrated that gut Camp expression is upregulated when type 1 diabetes-prone rats are protected from diabetes development. Unexpectedly, we have also identified novel CAMP expression in the pancreatic β-cells of rats, mice, and humans. CAMP was present even in sterile rat embryo islets, germ-free adult rat islets, and neogenic tubular complexes. Camp gene expression was downregulated in young BBdp rat islets before the onset of insulitis compared with control BBc rats. CAMP treatment of dispersed islets resulted in a significant increase in intracellular calcium mobilization, an effect that was both delayed and blunted in the absence of extracellular calcium. Additionally, CAMP treatment promoted insulin and glucagon secretion from isolated rat islets. Thus, CAMP is a promoter of islet paracrine signaling that enhances islet function and glucoregulation. Finally, daily treatment with the CAMP/LL-37 peptide in vivo in BBdp rats resulted in enhanced β-cell neogenesis and upregulation of potentially beneficial gut microbes. In particular, CAMP/LL-37 treatment shifted the abundance of specific bacterial populations, mitigating the gut dysbiosis observed in the BBdp rat. Taken together, these findings indicate a novel functional role for CAMP/LL-37 in islet biology and modification of gut microbiota.

Heme Oxygenase-1 Induction Prevents Autoimmune Diabetes in Association With Pancreatic Recruitment of M2-Like Macrophages, Mesenchymal Cells, and Fibrocytes

Immunoregulatory and regenerative processes are activated in the pancreas during the development of type 1 diabetes (T1D) but are insufficient to prevent the disease. We hypothesized that the induction of cytoprotective heme oxygenase-1 (HO-1) by cobalt protophoryrin (CoPP) would prevent T1D by promoting anti-inflammatory and pro-repair processes. Diabetes-prone BioBreeding rats received ip CoPP or saline twice per week for 3 weeks, starting at 30 days and were monitored for T1D. Immunohistochemistry, confocal microscopy, quantitative RT-PCR, and microarrays were used to evaluate postinjection pancreatic changes at 51 days, when islet inflammation is first visible. T1D was prevented in CoPP-treated rats (29% vs 73%). Pancreatic Hmox1 was up-regulated along with islet-associated CD68(+)HO-1(+) cells, which were also observed in a striking peri-lobular interstitial infiltrate. Most interstitial cells expressed the mesenchymal marker vimentin and the hematopoietic marker CD34. Spindle-shaped, CD34(+)vimentin(+) cells coexpressed collagen V, characteristic of fibrocytes. M2 macrophage factors Krüppel-like factor 4, CD163, and CD206 were expressed by interstitial cells, consistent with pancreatic upregulation of several M2-associated genes. CoPP upregulated islet-regenerating REG genes and increased neogenic REG3β(+) and insulin(+) clusters. Thus, short-term induction of HO-1 promoted a protective M2-like milieu in the pancreas and recruited mesenchymal cells, M2 macrophages, and fibrocytes that imparted immunoregulatory and pro-repair effects, preventing T1D.

The Role of Gluten in Celiac Disease and Type 1 Diabetes

Celiac disease (CD) and type 1 diabetes (T1D) are autoimmune conditions in which dietary gluten has been proven or suggested to play a pathogenic role. In CD; gluten is established as the instigator of autoimmunity; the autoimmune process is halted by removing gluten from the diet; which allows for resolution of celiac autoimmune enteropathy and subsequent normalization of serological markers of the disease. However; an analogous causative agent has not yet been identified for T1D. Nevertheless; the role of dietary gluten in development of T1D and the potentially beneficial effect of removing gluten from the diet of patients with T1D are still debated. In this review; we discuss the comorbid occurrence of CD and T1D and explore current evidences for the specific role of gluten in both conditions; specifically focusing on current evidence on the effect of gluten on the immune system and the gut microbiota.

CD4⁺ T-cell proliferation responses to wheat polypeptide stimulation in children at different stages of type 1 diabetes autoimmunity

AIMS

Our aim was to study whether immune responses to wheat-based proteins are related to the development of type 1 diabetes.

METHODS

We analysed proliferative T-cell responses after in vitro gliadin, gluten, whole wheat, and tetanus toxoid stimulation with a carboxyfluorescein succinimidyl ester (CFSE) based T-cell proliferation assay in children at various phases of type 1 diabetes autoimmunity and in healthy autoantibody-negative control children.

RESULTS

At an early stage of beta cell autoimmunity the strength and frequencies of positive proliferation responses to gliadin, gluten, and whole wheat did not differ between newly seroconverted children positive for one islet autoantibody and the controls. However, in prediabetic children with at least two islet autoantibodies and also in children with newly diagnosed type 1 diabetes positive T-cell responses to gliadin were significantly less frequent and the strength of gliadin responses was reduced when compared to the controls. No differences were seen in T-cell responses to wheat-based antigens when comparing children with long-lasting type 1 diabetes with healthy controls.

CONCLUSIONS/INTERPRETATION

Decreased in vitro T-cell responses to wheat-based antigens were observed in children with multiple islet autoantibodies and in those with newly diagnosed type 1 diabetes, probably reflecting a generally aberrant immune response during the development of type 1 diabetes.

Gut immune deficits in LEW.1AR1-iddm rats partially overcome by feeding a diabetes-protective diet

The gut immune system and its modification by diet have been implicated in the pathogenesis of type 1 diabetes (T1D). Therefore, we investigated gut immune status in non-diabetes-prone LEW.1AR1 and diabetes-prone LEW.1AR1-iddm rats and evaluated the effect of a low antigen, hydrolysed casein (HC)-based diet on gut immunity and T1D. Rats were weaned onto a cereal-based or HC-based diet and monitored for T1D. Strain and dietary effects on immune homeostasis were assessed in non-diabetic rats (50-60 days old) and rats with recent-onset diabetes using flow cytometry and immunohistochemistry. Immune gene expression was analysed in mesenteric lymph nodes (MLN) and jejunum using quantitative RT-PCR and PCR arrays. T1D was prevented in LEW.1AR1-iddm rats by feeding an HC diet. Diabetic LEW.1AR1-iddm rats had fewer lymphoid tissue T cells compared with LEW.1AR1 rats. The percentage of CD4(+)  Foxp3(+) regulatory T (Treg) cells was decreased in pancreatic lymph nodes (PLN) of diabetic rats. The jejunum of 50-day LEW.1AR1-iddm rats contained fewer CD3(+) T cells, CD163(+) M2 macrophages and Foxp3(+) Treg cells. Ifng expression was increased in MLN and Foxp3 expression was decreased in the jejunum of LEW.1AR1-iddm rats; Ifng/Il4 was decreased in jejunum of LEW.1AR1-iddm rats fed HC. PCR arrays revealed decreased expression of M2-associated macrophage factors in 50-day LEW.1AR1-iddm rats. Wheat peptides stimulated T-cell proliferation and activation in MLN and PLN cells from diabetic LEW.1AR1-iddm rats. LEW.1AR1-iddm rats displayed gut immune cell deficits and decreased immunoregulatory capacity, which were partially corrected in animals fed a low antigen, protective HC diet consistent with other models of T1D.

Parent experiences raising young people with type 1 diabetes and celiac disease

Authors of this qualitative descriptive study interviewed 30 parents concerning their experiences raising a child or adolescent with type 1 diabetes (T1D) and celiac disease (CD). Analysis revealed six themes: (a) health complications of T1D, (b) challenges of daily disease management, (c) financial concerns, (d) the young person's emotional/mental health, (e) experiences with healthcare providers, and (f) experiences with people outside the family and at school. Results suggest nurses need to be sensitive to challenges young people living with T1D and CD and their parents face, conduct ongoing assessments, and provide time during interactions to adequately address concerns.

Leaky gut, microbiota, and cancer: an incoming hypothesis

Multigenic disease development is dependent on both missing and overactivated pathways, just as the homeostasis of our body systems is the product of many complex, redundant mechanisms. The goal of finding a common factor in the disease pathogenesis is difficult, as genetic and pathophysiological data are still incomplete, and the individual variability is enormous. Nevertheless, the examination of the role of human microbiota in illnesses using animal models of human diseases reared in defined (gnotobiotic) conditions could allow insight into the unusual complexity of the mechanisms involved in the initiation and maintenance of chronic diseases, including cancer. Although the most important findings in this fascinating field are still to come, a hypothesis, which is more than speculative, can be made, as it is clear that our bacterial companions affect our fates more than previously assumed.

A gluten-free diet lowers NKG2D and ligand expression in BALB/c and non-obese diabetic (NOD) mice

The interplay between diet and immune parameters which could affect type 1 diabetes (T1D) pathogenesis is not sufficiently clarified. Intestinal up-regulation of the activating receptor natural killer group 2D (NKG2D) (CD314) and its ligands is a hallmark of coeliac disease. However, the direct effect of gluten on NKG2D expression is not known. We studied, by fluorescence activated cell sorter (lymphoid tissues) and reverse transcription–quantitative polymerase chain reaction (intestine and pancreatic islets), if a gluten-free diet (GF diet) from 4 weeks of age or a gluten-free diet introduced in breeding pairs (SGF diet), induced changes in NKG2D expression on DX5⁺(CD49b) natural killer (NK) cells, CD8⁺ T cells and in intestinal and islet levels of NKG2D and ligands in BALB/c and non-obese diabetic (NOD) mice. Gluten-free NOD mice had lower insulitis (P < 0·0001); reduced expression of NKG2D on DX5⁺ NK cells in spleen and auricular lymph nodes (P < 0·05); and on CD8⁺ T cells in pancreas-associated lymph nodes (P = 0·04). Moreover, the level of CD71 on DX5⁺ NK cells and CD8⁺ T cells (P < 0·005) was markedly reduced. GF and SGF mice had reduced expression of NKG2D and DX5 mRNA in intestine (P < 0·05). Differences in intestinal mRNA expression were found in mice at 8, 13 and 20 weeks. Intestinal expression of NKG2D ligands was reduced in SGF mice with lower expression of all ligands. In isolated islets, a SGF diet induced a higher expression of specific NKG2D ligands. Our data show that a gluten-free diet reduces the level of NKG2D and the expression of NKG2D ligands. These immunological changes may contribute to the lower T1D incidence associated with a gluten-free diet.

Dietary gluten and the development of type 1 diabetes

Gluten proteins differ from other cereal proteins as they are partly resistant to enzymatic processing in the intestine, resulting in a continuous exposure of the proteins to the intestinal immune system. In addition to being a disease-initiating factor in coeliac disease (CD), gluten intake might affect type 1 diabetes development. Studies in animal models of type 1 diabetes have documented that the pathogenesis is influenced by diet. Thus, a gluten-free diet largely prevents diabetes in NOD mice while a cereal-based diet promotes diabetes development. In infants, amount, timing and mode of introduction have been shown to affect the diabetogenic potential of gluten, and some studies now suggest that a gluten-free diet may preserve beta cell function. Other studies have not found this effect. There is evidence that the intestinal immune system plays a primary role in the pathogenesis of type 1 diabetes, as diabetogenic T cells are initially primed in the gut, islet-infiltrating T cells express gut-associated homing receptors, and mesenteric lymphocytes transfer diabetes from NOD mice to NOD/severe combined immunodeficiency (SCID) mice. Thus, gluten may affect diabetes development by influencing proportional changes in immune cell populations or by modifying the cytokine/chemokine pattern towards an inflammatory profile. This supports an important role for gluten intake in the pathogenesis of type 1 diabetes and further studies should be initiated to clarify whether a gluten-free diet could prevent disease in susceptible individuals or be used with newly diagnosed patients to stop disease progression.

Elevated CD8 T cell responses in type 1 diabetes patients to a 13 amino acid coeliac-active peptide from α-gliadin

Some type 1 diabetes (T1D) patients have been reported to exhibit T cell reactivity to wheat gluten. We tested the hypothesis that this T cell reactivity could be abolished by using prolyl-endopeptidase (PEP), an enzyme that cleaves peptide bonds after proline. Peripheral blood mononuclear cells (PBMCs) were isolated from T1D patients and healthy controls. PBMCs were stimulated with a peptic-tryptic digest of wheat gluten; a peptic-tryptic-PEP digest of wheat gluten; and a 13 amino acid peptide from wheat gluten. Fluorescent-labelled antibodies to CD3, CD4 and CD8 cell marker proteins were utilized to determine proliferative responses of CD3, CD4 and CD8 T cells. There were no significant differences in proliferative responses of CD3 or CD4 T cells to the wheat gluten antigens. A significantly higher proportion of CD8(+) T cells from T1D patients proliferated in the presence of the 13 amino acid peptide than when challenged with the peptic-tryptic or the peptic-tryptic-PEP digests of wheat gluten. PEP treatment had no significant effect on CD8 T cell reactivity to the peptic-trytic digest of wheat gluten. Our results suggest that wheat gluten-derived peptides, containing ≤ 13 amino acids, may evoke T cell responses in T1D patients.

Casein hydrolysate diet controls intestinal T cell activation, free radical production and microbial colonisation in NOD mice

AIMS/HYPOTHESIS

Dietary and microbial factors and the gut immune system are important in autoimmune diabetes. We evaluated inflammatory activity in the whole gut in prediabetic NOD mice using ex vivo imaging of reactive oxygen and nitrogen species (RONS), and correlated this with the above-mentioned factors.

METHODS

NOD mice were fed a normal diet or an anti-diabetogenic casein hydrolysate (CH) diet. RONS activity was detected by chemiluminescence imaging of the whole gut. Proinflammatory and T cell cytokines were studied in the gut and islets, and dietary effects on gut microbiota and short-chain fatty acids were determined.

RESULTS

Prediabetic NOD mice displayed high RONS activity in the epithelial cells of the distal small intestine, in conjunction with a proinflammatory cytokine profile. RONS production was effectively reduced by the CH diet, which also controlled (1) the expression of proinflammatory cytokines and colonisation-dependent RegIIIγ (also known as Reg3g) in ileum; (2) intestinal T cell activation; and (3) islet cytokines. The CH diet diminished microbial colonisation, increased the Bacteroidetes:Firmicutes ratio, and reduced lactic acid and butyric acid production in the gut.

CONCLUSIONS/INTERPRETATION

Epithelial RONS production and proinflammatory T cell activation appears in the ileum of NOD mice after weaning to normal laboratory chow, but not after weaning to an anti-diabetogenic CH diet. Our data suggest a link between dietary factors, microbial colonisation and mucosal immune activation in NOD mice.

Promotion of autoimmune diabetes by cereal diet in the presence or absence of microbes associated with gut immune activation, regulatory imbalance, and altered cathelicidin antimicrobial Peptide

We are exposed to millions of microbial and dietary antigens via the gastrointestinal tract, which likely play a key role in type 1 diabetes (T1D). We differentiated the effects of these two major environmental factors on gut immunity and T1D. Diabetes-prone BioBreeding (BBdp) rats were housed in specific pathogen-free (SPF) or germ-free (GF) conditions and weaned onto diabetes-promoting cereal diets or a protective low-antigen hydrolyzed casein (HC) diet, and T1D incidence was monitored. Fecal microbiota 16S rRNA genes, immune cell distribution, and gene expression in the jejunum were analyzed. T1D was highest in cereal-SPF (65%) and cereal-GF rats (53%) but inhibited and delayed in HC-fed counterparts. Nearly all HC-GF rats remained diabetes-free, whereas HC-fed SPF rats were less protected (7 vs. 29%). Bacterial communities differed in SPF rats fed cereal compared with HC. Cereal-SPF rats displayed increased gut CD3(+) and CD8α(+) lymphocytes, ratio of Ifng to Il4 mRNA, and Lck expression, indicating T-cell activation. The ratio of CD3(+) T cells expressing the Treg marker Foxp3(+) was highest in HC-GF and lowest in cereal-SPF rats. Resident CD163(+) M2 macrophages were increased in HC-protected rats. The cathelicidin antimicrobial peptide (Camp) gene was upregulated in the jejunum of HC diet-protected rats, and CAMP(+) cells colocalized with CD163. A cereal diet was a stronger promoter of T1D than gut microbes in association with impaired gut immune homeostasis.

The association between IgG4 antibodies to dietary factors, islet autoimmunity and type 1 diabetes: the Diabetes Autoimmunity Study in the Young

Background

Infant dietary exposures have been linked to type 1 diabetes (T1D) development. IgG4 antibody responses to food antigens are associated with food intolerances but have not been explored prospectively in the period preceding T1D.

Methods

Using a case-cohort design, IgG4 antibodies to ß-lactoglobulin, gluten, and ovalbumin were measured in plasma collected annually from 260 DAISY participants. Of those, 77 developed islet autoimmunity (IA), defined as positive for either insulin, GAD65 or IA-2 autoantibodies on two consecutive visits, and 22 developed T1D.

Results

In mixed model analysis adjusting for HLA-DR status, T1D family history, age and ethnicity, higher ß-lactoglobulin IgG4 concentrations were associated with shorter breastfeeding duration (beta = −0.03, 95% Confidence Interval: −0.05, −0.006) and earlier first cow’s milk exposure (beta = −0.04, 95% Confidence Interval: −0.08, 0.00). Higher gluten IgG4 was associated with older age at gluten introduction (beta = 0.06, 95% Confidence Interval: 0.00, 0.13). In proportional hazards analysis adjusting for HLA-DR status, T1D family history and ethnicity, IgG4 against individual or multiple dietary antigens throughout childhood were not associated with IA. In addition, mean antigen-specific IgG4 concentrations in infancy (age <2 years) were not associated with risk of IA nor progression to T1D. Higher ovalbumin IgG4 at first IA positive visit was marginally associated with progression to T1D (Hazard Ratio: 1.39, 95% Confidence Interval: 1.00, 1.92).

Conclusion

We found no association between the IgG4 response to β-lactoglobulin, gluten, and the development of either IA or T1D. The association between higher ovalbumin and progression to T1D in children with IA should be explored in other populations.

Stromal cells induce Th17 during Helicobacter pylori infection and in the gastric tumor microenvironment

Gastric cancer is associated with chronic inflammation and Helicobacter pylori infection. Th17 cells are CD4(+) T cells associated with infections and inflammation; but their role and mechanism of induction during carcinogenesis is not understood. Gastric myofibroblasts/fibroblasts (GMF) are abundant class II MHC expressing cells that act as novel antigen presenting cells. Here we have demonstrated the accumulation of Th17 in H. pylori-infected human tissues and in the gastric tumor microenvironment. GMF isolated from human gastric cancer and H. pylori infected tissues co-cultured with CD4(+) T cells induced substantially higher levels of Th17 than GMF from normal tissues in an IL-6, TGF-β, and IL-21 dependent manner. Th17 required interaction with class II MHC on GMF for activation and proliferation. These studies suggest that Th17 are induced during both H. pylori infection and gastric cancer in the inflammatory milieu of gastric stroma and may be an important link between inflammation and carcinogenesis.

Gluten-free diet reduces adiposity, inflammation and insulin resistance associated with the induction of PPAR-alpha and PPAR-gamma expression

Gluten exclusion (protein complex present in many cereals) has been proposed as an option for the prevention of diseases other than coeliac disease. However, the effects of gluten-free diets on obesity and its mechanisms of action have not been studied. Thus, our objective was to assess whether gluten exclusion can prevent adipose tissue expansion and its consequences. C57BL/6 mice were fed a high-fat diet containing 4.5% gluten (Control) or no gluten (GF). Body weight and adiposity gains, leukocyte rolling and adhesion, macrophage infiltration and cytokine production in adipose tissue were assessed. Blood lipid profiles, glycaemia, insulin resistance and adipokines were measured. Expression of the PPAR-α and γ, lipoprotein lipase (LPL), hormone sensitive lipase (HSL), carnitine palmitoyl acyltransferase-1 (CPT-1), insulin receptor, GLUT-4 and adipokines were assessed in epidydimal fat. Gluten-free animals showed a reduction in body weight gain and adiposity, without changes in food intake or lipid excretion. These results were associated with up-regulation of PPAR-α, LPL, HSL and CPT-1, which are related to lipolysis and fatty acid oxidation. There was an improvement in glucose homeostasis and pro-inflammatory profile-related overexpression of PPAR-γ. Moreover, intravital microscopy showed a lower number of adhered cells in the adipose tissue microvasculature. The overexpression of PPAR-γ is related to the increase of adiponectin and GLUT-4. Our data support the beneficial effects of gluten-free diets in reducing adiposity gain, inflammation and insulin resistance. The data suggests that diet gluten exclusion should be tested as a new dietary approach to prevent the development of obesity and metabolic disorders.

Leaky gut and autoimmune diseases

Autoimmune diseases are characterized by tissue damage and loss of function due to an immune response that is directed against specific organs. This review is focused on the role of impaired intestinal barrier function on autoimmune pathogenesis. Together with the gut-associated lymphoid tissue and the neuroendocrine network, the intestinal epithelial barrier, with its intercellular tight junctions, controls the equilibrium between tolerance and immunity to non-self antigens. Zonulin is the only physiologic modulator of intercellular tight junctions described so far that is involved in trafficking of macromolecules and, therefore, in tolerance/immune response balance. When the zonulin pathway is deregulated in genetically susceptible individuals, autoimmune disorders can occur. This new paradigm subverts traditional theories underlying the development of these diseases and suggests that these processes can be arrested if the interplay between genes and environmental triggers is prevented by re-establishing the zonulin-dependent intestinal barrier function. Both animal models and recent clinical evidence support this new paradigm and provide the rationale for innovative approaches to prevent and treat autoimmune diseases.

What is the key environmental trigger in type 1 diabetes--is it viruses, or wheat gluten, or both?

Prevention and treatment of type 1 diabetes is hampered by the fact that the key environmental trigger(s) of the disease is still unknown. Much of the data on this subject points to two possibilities, viruses and wheat gluten. Viruses appear to be involved as an etiological agent in some cases of type 1 diabetes, particularly in fulminant type 1 diabetes. Further analysis of the data suggests that viruses are not the sole trigger of type 1 diabetes in humans, and that wheat gluten may play a role in initiating the disease. Viruses may be the key environmental trigger in some cases of type 1 diabetes, and wheat gluten in others. Conceivably, some cases of type 1 diabetes might be caused by viruses and wheat gluten acting together as disease triggers.

Up-regulation of small intestinal interleukin-17 immunity in untreated coeliac disease but not in potential coeliac disease or in type 1 diabetes

Up-regulation of interleukin (IL)-17 in small intestinal mucosa has been reported in coeliac disease (CD) and in peripheral blood in type 1 diabetes (T1D). We explored mucosal IL-17 immunity in different stages of CD, including transglutaminase antibody (TGA)-positive children with potential CD, children with untreated and gluten-free diet-treated CD and in children with T1D. Immunohistochemistry was used for identification of IL-17 and forkhead box protein 3 (FoxP3)-positive cells and quantitative polymerase chain reaction (qPCR) for IL-17, FoxP3, retinoic acid-related orphan receptor (ROR)c and interferon (IFN)-γ transcripts. IL-1β, IL-6 and IL-17 were studied in supernatants from biopsy cultures. Expression of the apoptotic markers BAX and bcl-2 was evaluated in IL-17-stimulated CaCo-2 cells. The mucosal expression of IL-17 and FoxP3 transcripts were elevated in individuals with untreated CD when compared with the TGA-negative reference children, children with potential CD or gluten-free diet-treated children with CD (P < 0·005 for all IL-17 comparisons and P < 0·01 for all FoxP3 comparisons). The numbers of IL-17-positive cells were higher in lamina propria in children with CD than in children with T1D (P < 0·05). In biopsy specimens from patients with untreated CD, enhanced spontaneous secretion of IL-1β, IL-6 and IL-17 was seen. Activation of anti-apoptotic bcl-2 in IL-17-treated CaCo-2 epithelial cells suggests that IL-17 might be involved in mucosal protection. Up-regulation of IL-17 could, however, serve as a biomarker for the development of villous atrophy and active CD.

Is the origin of type 1 diabetes in the gut?

In type 1 diabetes, insulin-producing beta-cells in the pancreas are destroyed by immune-mediated mechanisms. The manifestation of the disease is preceded by the so-called pre-diabetic period that may last several years and is characterized by the appearance of circulating autoantibodies against beta-cell antigens. The role of the gut as a regulator of type 1 diabetes was suggested in animal studies, in which changes affecting the gut immune system modulated the incidence of diabetes. Dietary interventions, alterations in the intestinal microbiota and exposure to enteric pathogens, regulate the development of autoimmune diabetes in animal models. It has been demonstrated that these modulations affect the gut barrier mechanisms and intestinal immunity. Because the pancreas and the gut belong to the same intestinal immune system, the link between autoimmune diabetes and the gut is not unexpected. The gut hypothesis in the development of type 1 diabetes is also supported by the observations made in human type 1 diabetes. Early diet could modulate the development of beta-cell autoimmunity; weaning to hydrolysed casein formula decreased the risk of beta-cell autoimmunity by age 10 in the infants at genetic risk. Increased gut permeability, intestinal inflammation with impaired regulatory mechanisms and dysregulated oral tolerance have been observed in children with type 1 diabetes. The factors that contribute to these intestinal alterations are not known, but interest is focused on the microbial stimuli and function of innate immunity. It is likely that our microbial environment does not support the healthy maturation of the gut and tolerance in the gut, and this leads to the increasing type 1 diabetes as well as other immune-mediated diseases regulated by intestinal immune system. Thus, the interventions, aiming to prevent or treat type 1 diabetes in humans, should be targeting the gut immune system.

Sensitization to gliadin induces moderate enteropathy and insulitis in nonobese diabetic-DQ8 mice

Celiac disease (CD) is frequently diagnosed in patients with type 1 diabetes (T1D), and T1D patients can exhibit Abs against tissue transglutaminase, the auto-antigen in CD. Thus, gliadin, the trigger in CD, has been suggested to have a role in T1D pathogenesis. The objective of this study was to investigate whether gliadin contributes to enteropathy and insulitis in NOD-DQ8 mice, an animal model that does not spontaneously develop T1D. Gliadin-sensitized NOD-DQ8 mice developed moderate enteropathy, intraepithelial lymphocytosis, and barrier dysfunction, but not insulitis. Administration of anti-CD25 mAbs before gliadin-sensitization induced partial depletion of CD25(+)Foxp3(+) T cells and led to severe insulitis, but did not exacerbate mucosal dysfunction. CD4(+) T cells isolated from pancreatic lymph nodes of mice that developed insulitis showed increased proliferation and proinflammatory cytokines after incubation with gliadin but not with BSA. CD4(+) T cells isolated from nonsensitized controls did not response to gliadin or BSA. In conclusion, gliadin sensitization induced moderate enteropathy in NOD-DQ8 mice. However, insulitis development required gliadin-sensitization and partial systemic depletion of CD25(+)Foxp3(+) T cells. This humanized murine model provides a mechanistic link to explain how the mucosal intolerance to a dietary protein can lead to insulitis in the presence of partial regulatory T cell deficiency.

The gut as a regulator of early inflammation in type 1 diabetes

PURPOSE OF REVIEW

Several studies indicate that factors affecting the gut are capable of modulating the development of autoimmune diabetes. This review discusses the recent research on these mechanisms, which may reveal novel pathogenic pathways and new possibilities for prevention of type 1 diabetes (T1D).

RECENT FINDINGS

The role of the gut as a regulator of T1D is mainly based on animal studies in which changes affecting the gut immune system have been shown to modulate the immune-mediated destruction of insulin-producing beta-cells. Dietary interventions, alterations in the intestinal microbiota and exposure to enteral pathogens regulate the development of autoimmune diabetes in animal models. In several studies, it has been demonstrated that these modulations affect the gut barrier mechanisms and intestinal immunity. Also, in humans, increased gut permeability and intestinal inflammation are associated with T1D. A recent report of dietary intervention study in infants at genetic risk of T1D showed that early diet could modulate the development of beta-cell autoimmunity in humans; weaning to hydrolyzed casein formula decreased the risk of beta-cell autoimmunity by age 10.

SUMMARY

The gut modulation affecting permeability, inflammation and microbiota is evidently associated with the regulation of the inflammation leading to beta-cell destruction. Although the mechanisms of action are not fully understood, the recent research points out the lines of approach for the prevention of T1D.

Zonulin and its regulation of intestinal barrier function: the biological door to inflammation, autoimmunity, and cancer

The primary functions of the gastrointestinal tract have traditionally been perceived to be limited to the digestion and absorption of nutrients and to electrolytes and water homeostasis. A more attentive analysis of the anatomic and functional arrangement of the gastrointestinal tract, however, suggests that another extremely important function of this organ is its ability to regulate the trafficking of macromolecules between the environment and the host through a barrier mechanism. Together with the gut-associated lymphoid tissue and the neuroendocrine network, the intestinal epithelial barrier, with its intercellular tight junctions, controls the equilibrium between tolerance and immunity to non-self antigens. Zonulin is the only physiological modulator of intercellular tight junctions described so far that is involved in trafficking of macromolecules and, therefore, in tolerance/immune response balance. When the finely tuned zonulin pathway is deregulated in genetically susceptible individuals, both intestinal and extraintestinal autoimmune, inflammatory, and neoplastic disorders can occur. This new paradigm subverts traditional theories underlying the development of these diseases and suggests that these processes can be arrested if the interplay between genes and environmental triggers is prevented by reestablishing the zonulin-dependent intestinal barrier function. This review is timely given the increased interest in the role of a "leaky gut" in the pathogenesis of several pathological conditions targeting both the intestine and extraintestinal organs.

Restoration of impaired intestinal barrier function by the hydrolysed casein diet contributes to the prevention of type 1 diabetes in the diabetes-prone BioBreeding rat

AIMS/HYPOTHESIS

Impaired intestinal barrier function is observed in type 1 diabetes patients and animal models of the disease. Exposure to diabetogenic antigens from the intestinal milieu due to a compromised intestinal barrier is considered essential for induction of the autoimmune process leading to type 1 diabetes. Since a hydrolysed casein (HC) diet prevents autoimmune diabetes onset in diabetes-prone (DP)-BioBreeding (BB) rats, we studied the role of the HC diet on intestinal barrier function and, therefore, prevention of autoimmune diabetes onset in this animal model.

METHODS

DP-BB rats were fed the HC diet from weaning onwards and monitored for autoimmune diabetes development. Intestinal permeability was assessed in vivo by lactulose-mannitol test and ex vivo by measuring transepithelial electrical resistance (TEER). Levels of serum zonulin, a physiological tight junction modulator, were measured by ELISA. Ileal mRNA expression of Myo9b, Cldn1, Cldn2 and Ocln (which encode the tight junction-related proteins myosin IXb, claudin-1, claudin-2 and occludin) and Il-10, Tgf-ß (also known as Il10 and Tgfb, respectively, which encode regulatory cytokines) was analysed by quantitative PCR.

RESULTS

The HC diet reduced autoimmune diabetes by 50% in DP-BB rats. In DP-BB rats, prediabetic gut permeability negatively correlated with the moment of autoimmune diabetes onset. The improved intestinal barrier function that was induced by HC diet in DP-BB rats was visualised by decreasing lactulose:mannitol ratio, decreasing serum zonulin levels and increasing ileal TEER. The HC diet modified ileal mRNA expression of Myo9b, and Cldn1 and Cldn2, but left Ocln expression unaltered.

CONCLUSIONS/INTERPRETATION

Improved intestinal barrier function might be an important intermediate in the prevention of autoimmune diabetes by the HC diet in DP-BB rats. Effects on tight junctions, ileal cytokines and zonulin production might be important mechanisms for this effect.

Infant and childhood diet and type 1 diabetes risk: recent advances and prospects

Type 1 diabetes is a chronic autoimmune disease characterized by a preclinical period of autoimmunity. It is well accepted that both genetic and environmental factors contribute to disease risk. Given that type 1 diabetes, and its preclinical autoimmunity, appear early in life, infant and childhood diet have been implicated as potential initiating exposures in the etiology of the disease. Several publications in the past year have provided further evidence for existing hypotheses regarding the roles of wheat, cow's milk, omega-3 fatty acids, and the maternal diet during pregnancy. However, inconsistencies in findings between studies suggest the need for collaboration and standardization of study methods to move forward in research in this area. One such example of this is the TEDDY (The Environmental Determinants of Diabetes in the Young) study, which is an international, multicenter birth cohort study with standardized recruitment, dietary collection methodologies, and analytic approaches.

Infant feeding and the risk of type 1 diabetes

Type 1 diabetes is generally considered to be a chronic, immune-mediated disease with a subclinical prodrome during which beta cell autoimmunity becomes overt disease at a variable rate in genetically susceptible individuals. Accumulated evidence supports a critical role of environmental factors in its development. Prospective birth cohort studies show that the first signs of beta cell autoimmunity may be initiated during the first year of life. This implies that risk factors for beta cell autoimmunity and type 1 diabetes must be operative in infancy. Early nutrition provides essential exogenous exposures in that period. This article discusses the role of factors related to infant nutrition in the development of beta cell autoimmunity and type 1 diabetes and the potential mechanistic pathways involved. So far, no specific dietary factor has been shown to be an unequivocal risk factor for beta cell autoimmunity or type 1 diabetes, and there are a number of contradictory observations with regard to the effect of various foods. This may reflect geographic and cultural differences in infant-feeding practices. Most studies suggest that the early introduction of complex foreign proteins may be a risk factor for beta cell autoimmunity, and a pilot intervention trial has implied that weaning to a highly hydrolyzed formula may decrease the risk of beta cell autoimmunity. Lack of vitamin D supplementation and accelerated growth might increase the risk of type 1 diabetes. Additional work, which includes the application of modern approaches such as metabolomics and epigenomics, is needed to discern the contribution of dietary factors in infancy to the diabetic disease process.

Environmental factors and primary prevention in type 1 diabetes

The incidence of type 1 diabetes has been increasing rapidly among children in most European countries overthe last decades. Despite of the known strong genetic component in the disease only environmental factors can explain such a rapid change. The increase in incidence has been most conspicuous in the youngest age group, which emphasizes the importance of infancy and early environmental exposures. Nutritional and infectious factors affecting the young child or even the mother during pregnancy have been implicated to be important in the pathogenesis. The identification of single factors has been extremely difficult as reflected by many controversial reports on their importance. This difficulty may also be due to the heterogeneity of the disease mechanisms. Multiple mechanisms in different pathways may ultimately be responsible for beta-cell destruction. In most cases the disease is probably caused by a complex interplay between multiple factors including distinct genetic polymorphisms and environmental effects. Exploration of these pathways is needed for the development of effective preventive measures. The implementation of primary prevention trials will ultimately prove the value of various concepts generated for the disease pathogenesis.