Oral exposure to diabetes-promoting food or immunomodulators in neonates alters gut cytokines and diabetes

A Gluten-Free Diet during Pregnancy and Early Life Increases Short Chain Fatty Acid-Producing Bacteria and Regulatory T Cells in Prediabetic NOD Mice

The incidence of the autoimmune disease type 1 diabetes is increasing, likely caused by environmental factors. A gluten-free diet has previously been shown to ameliorate autoimmune diabetes in non-obese diabetic (NOD) mice and humans. Although the exact mechanisms are not understood, interventions influencing the intestinal microbiota early in life affect the risk of type 1 diabetes. Here, we characterize how NOD mice that are fed a gluten-free (GF) diet differ from NOD mice that are fed a gluten-containing standard (STD) diet in terms of their microbiota composition by 16S rRNA gene amplicon sequencing and pancreatic immune environment by real-time quantitative PCR at the prediabetic stage at 6 and 13 weeks of age. Gut microbiota analysis revealed highly distinct microbiota compositions in both the cecum and the colon of GF-fed mice compared with STD-fed mice. The microbiotas of the GF-fed mice were characterized by an increased Firmicutes/Bacteroidetes ratio, an increased abundance of short chain fatty acid (particularly butyrate)-producing bacteria, and a reduced abundance of Lactobacilli compared with STD mice. We found that the insulitis score in the GF mice was significantly reduced compared with the STD mice and that the markers for regulatory T cells and T helper 2 cells were upregulated in the pancreas of the GF mice. In conclusion, a GF diet during pre- and early post-natal life induces shifts in the cecal and colonic microbiota compatible with a less inflammatory environment, providing a likely mechanism for the protective effect of a GF diet in humans.

Environmental Triggering of Type 1 Diabetes Autoimmunity

Type 1 diabetes (T1D) is a chronic autoimmune disease in which pancreatic islet β cells are destroyed by immune cells, ultimately leading to overt diabetes. The progressive increase in T1D incidence over the years points to the role of environmental factors in triggering or accelerating the disease process which develops on a highly multigenic susceptibility background. Evidence that environmental factors induce T1D has mostly been obtained in animal models. In the human, associations between viruses, dietary habits or changes in the microbiota and the development of islet cell autoantibodies or overt diabetes have been reported. So far, prediction of T1D development is mostly based on autoantibody detection. Future work should focus on identifying a causality between the different environmental risk factors and T1D development to improve prediction scores. This should allow developing preventive strategies to limit the T1D burden in the future.

The Role of the Gut Microbiota in the Pathogenesis of Diabetes

Diabetes mellitus is a significant clinical and therapeutic problem because it can lead to serious long-term complications. Its pathogenesis is not fully understood, but there are indications that dysbiosis can play a role in the development of diabetes, or that it appears during the course of the disease. Changes in microbiota composition are observed in both type 1 diabetes (T1D) and type 2 diabetes (T2D) patients. These modifications are associated with pro-inflammation, increased intestinal permeability, endotoxemia, impaired β-cell function and development of insulin resistance. This review summarizes the role of the gut microbiota in healthy individuals and the changes in bacterial composition that can be associated with T1D or T2D. It also presents new developments in diabetes therapy based on influencing the gut microbiota as a promising method to alter the course of diabetes. Moreover, it highlights the lacking data and suggests future directions needed to prove the causal relationship between dysbiosis and diabetes, both T1D and T2D.

Oral Limonite Supplement Ameliorates Glucose Intolerance in Diabetic and Obese Mice

Introduction

Diabetes mellitus is a serious threat to public health worldwide. It causes a substantial economic burden, mental and physical disabilities, poor quality of life, and high mortality. Limonite is formed when iron-rich materials from the underground emerge and oxidized on the ground surface. It is currently used to purify contaminated water, absorption of irritant gases, and improve livestock breeding. Limonite can change the composition of environmental microbial communities. In the present study, we evaluated whether limonite can ameliorate glucose metabolism abnormalities by remodeling the gut microbiome.

Methods

The investigation was performed using mouse models of streptozotocin-induced diabetes mellitus and high-calorie diet-induced metabolic syndrome.

Results

Oral limonite supplement was associated with significant body weight recovery, reduced glycemia with improved insulin secretion, increased number of regulatory T cells, and abundant beneficial gut microbial populations in mice with diabetes mellitus compared to control. Similarly, mice with obesity fed with limonite supplements had significantly reduced body weight, insulin resistance, steatohepatitis, and systemic inflammatory response with significant gut microbiome remodeling.

Conclusion

This study demonstrates that limonite supplement ameliorates abnormal glucose metabolism in diabetes mellitus and obesity. Gut microbiome remodeling, inhibition of inflammatory cytokines, and the host immune response regulation may explain the limonite’s beneficial activity under pathological conditions in vivo.

Early Nutrition and Risk of Type 1 Diabetes: The Role of Gut Microbiota

Type 1 diabetes (T1D) appears most frequently in childhood, with an alarming increasing incidence in the last decades. Although the genetic predisposition is a major risk factor, it cannot solely explain the complex etiology of T1D which is still not fully understood. In this paper, we reviewed the most recent findings on the role of early nutrition and the involvement of the gut microbiota in the etiopathogenesis of T1D. The main conclusions that are withdrawn from the current literature regarding alleviating the risk of developing T1D through nutrition are the encouragement of long-term breast-feeding for at least the first 6 months of life and the avoidance of early complementary foods and gluten introduction (before 4 months of age) as well as cow milk introduction before 12 months of life. These detrimental feeding habits create a gut microbiota dysbiotic state that can contribute to the onset of T1D in infancy. Finally, we discussed the possibility to introduce probiotics, prebiotics and post-biotics in the prevention of T1D.

Association between Bioactive Molecules in Breast Milk and Type 1 Diabetes Mellitus

The association between breastfeeding and type 1 diabetes mellitus (T1DM) is controversial. However, several recent studies have established a link between these two factors, necessitating a need to review this subject to raise public awareness. Current research indicates that breast milk contains a variety of bioactive substances including immunoglobulins, oligosaccharides, insulin, lactoferrin, lysozyme, cytokines, epidermal growth factors, leukocytes, nucleotides, beneficial bacteria and vitamins. Such substances strengthen the breastfeeding infant's immune system, both directly, by increasing gut microbiota diversity and attacking harmful bacteria and pro-inflammatory molecules, and indirectly, by increasing thymus performance. Accordingly, a lack of or inadequate breastfeeding may predispose infants to several autoimmune disorders, including T1DM. Nursing mothers and caregivers are therefore advised to follow optimal breastfeeding practices prior to introducing complementary foods.

Role of Dietary Gluten in Development of Celiac Disease and Type I Diabetes: Management Beyond Gluten-Free Diet

Gluten triggers Celiac Disease (CD) and type I diabetes in genetically predisposed population of human leukocyte antigen DQ2/DQ8+ and associates with disorders such as schizophrenia and autism. Application of a strict gluten-free diet is the only well-established treatment for patients with CD, whereas the treatment for patients with celiac type I diabetes may be depend on the timing and frequency of the diet. The application of a gluten-free diet in patients with CD may contribute to the development of metabolic syndrome and nonalcoholic fatty liver disease and may also lead to a high glycemic index, low fiber diet and micronutrient deficiencies. The alteration of copper bioavailability (deficient, excess or aberrant coordination) may contribute to the onset and progress of related pathologies. Therefore, nutrient intake of patients on a gluten-free diet should be the focus of future researches. Other gluten-based therapies have been rising with interest such as enzymatic pretreatment of gluten, oral enzyme supplements to digest dietary gluten, gluten removal by breeding wheat varieties with reduced or deleted gluten toxicity, the development of polymeric binders to suppress gluten induced pathology.

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.

Gut Microbiota and Type 1 Diabetes

Recently, the onset of type 1 diabetes (T1D) has increased rapidly and became a major public health concern worldwide. Various factors are associated with the development of T1D, such as diet, genome, and intestinal microbiota. The gastrointestinal (GI) tract harbors a complex and dynamic population of microorganisms, the gut microbiota, which exert a marked influence on the host homeostasis and metabolic diseases. Recent evidence shows that altered gut bacterial composition (dysbiosis) is highly associated with the pathogenesis of insulin dysfunction and T1D and, thus, targeting gut microbiota may serve as a therapeutic potential for T1D patients. In this study, we updated the effect of gut microbiota on T1D and potential mechanisms were discussed.

Modulation of the diet and gastrointestinal microbiota normalizes systemic inflammation and β-cell chemokine expression associated with autoimmune diabetes susceptibility

Environmental changes associated with modern lifestyles may underlie the rising incidence of Type 1 diabetes (T1D). Our previous studies of T1D families and the BioBreeding (BB) rat model have identified a peripheral inflammatory state that is associated with diabetes susceptibility, consistent with pattern recognition receptor ligation, but is independent of disease progression. Here, compared to control strains, islets of spontaneously diabetic BB DRlyp/lyp and diabetes inducible BB DR+/+ weanlings provided a standard cereal diet expressed a robust proinflammatory transcriptional program consistent with microbial antigen exposure that included numerous cytokines/chemokines. The dependence of this phenotype on diet and gastrointestinal microbiota was investigated by transitioning DR+/+ weanlings to a gluten-free hydrolyzed casein diet (HCD) or treating them with antibiotics to alter/reduce pattern recognition receptor ligand exposure. Bacterial 16S rRNA gene sequencing revealed that these treatments altered the ileal and cecal microbiota, increasing the Firmicutes:Bacteriodetes ratio and the relative abundances of lactobacilli and butyrate producing taxa. While these conditions did not normalize the inherent hyper-responsiveness of DR+/+ rat leukocytes to ex vivo TLR stimulation, they normalized plasma cytokine levels, plasma TLR4 activity levels, the proinflammatory islet transcriptome, and β-cell chemokine expression. In lymphopenic DRlyp/lyp rats, HCD reduced T1D incidence, and the introduction of gluten to this diet induced islet chemokine expression and abrogated protection from diabetes. Overall, these studies link BB rat islet-level immunocyte recruiting potential, as measured by β-cell chemokine expression, to a genetically controlled immune hyper-responsiveness and innate inflammatory state that can be modulated by diet and the intestinal microbiota.

Occupation with grain crops is associated with lower type 1 diabetes incidence: Registry-based case-control study

Intranasal administration of gliadin prevents autoimmune diabetes in non-obese diabetic mice. The current study was designed to investigate if bakers are intranasally exposed to gluten during work and whether occupation as baker is inversely associated with type 1 diabetes. Gliadin was measured in nasal swabs from eight bakers and butchers. The odds ratio of type 1 diabetes in selected profession groups was analysed in a registry-based case-control study with data from 1980 to 2010 derived from Statistics Denmark. The cohort included 1,210,017 Danish individuals, thereof 15,451 with type 1 diabetes (1.28%). Average nasal gliadin swab content after full working days was 6.3 μg (confidence interval (CI): 2.8 to 9.7) among bakers, while no nasal gliadin was detected among butchers. The odds ratio of type 1 diabetes was lower among bakers (OR = 0.57; CI: 0.52 to 0.62) and agriculture workers occupied with production of grains (OR = 0.65; CI: 0.56 to 0.75). Bakers had a lower odds ratio of type 1 diabetes, which potentially could be attributed to exposure of nasal mucosal gluten during work, as observed in this study. If other studies confirm the present observations, intranasal gliadin administration could possibly be an easy and safe approach for the prevention of type 1 diabetes in high-risk individuals or prediabetic subjects.

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.

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.

Neonatal Gastrointestinal and Respiratory Microbiome in Cystic Fibrosis: Potential Interactions and Implications for Systemic Health

PURPOSE

The gastrointestinal microbiome plays a critical role in nutrition and metabolic and immune functions in infants and young children and has implications for lifelong health. Cystic fibrosis (CF) transmembrane conductance regulator (CFTR) mutations in CF result in viscous mucous production, frequent exposure to antibiotics, and atypical colonization patterns, resulting in an evolving dysbiosis of the gastrointestinal and respiratory microsystems; dysbiosis in CF results in systemic inflammation, chronic infection, and dysregulation of immune function. Dysbiosis in both the respiratory system and gut contributes to undernutrition, growth failure, and long-term respiratory and systemic morbidity in infants and children with CF. Understanding the role that the gut and respiratory microbiome plays in health or disease progression in CF will afford opportunities to better identify interventions to affect clinical changes.

METHODS

Summary was done of the pertinent literature in CF and the study of the microbiome and probiotics.

FINDINGS

New studies have identified bacteria in the respiratory tract in CF that are typically members of the intestinal microbiota, and enteral exposures to breast milk and probiotics are associated with prolonged periods of respiratory stability in CF.

IMPLICATIONS

Understanding the complex interactions between the CFTR mutations, microbial colonization, and mucosal and systemic immunity is of major importance to inform new treatment strategies (such as restoring a healthier microbiome with probiotics or dietary interventions) to improve nutritional status and immune competence and to decrease morbidity and mortality in CF.

Gluten-Free Diet Only during Pregnancy Efficiently Prevents Diabetes in NOD Mouse Offspring

Studies have documented that the pathogenesis of autoimmune diabetes is influenced by the intake of gluten. Aims. To investigate the importance of gluten exposure during pregnancy and the subsequent development of autoimmune diabetes in offspring. Methods. Nonobese diabetic mice were divided into 7 groups to receive combinations of gluten-free and standard diet before, during, or after pregnancy. Diabetes incidence in offspring was followed in each group (n = 16-27) for 310 days. Insulitis score and intestinal expression of T-cell transcription factors (RT-QPCR) were evaluated in animals from the different diet groups. Results. If mothers were fed a gluten-free diet only during pregnancy, the development of autoimmune diabetes in offspring was almost completely prevented with an incidence reduction from 62.5% in gluten-consuming mice to 8.3% (p < 0.0001) in the gluten-free group. The islets of Langerhans were less infiltrated (p < 0.001) and the intestinal expression of RORγt (Th17) (p < 0.0001) reduced in mice whose mothers were Gluten-free during pregnancy. Conclusion. A gluten-free diet exclusively during pregnancy efficiently prevents autoimmune diabetes development in offspring and reduces insulitis and intestinal expression of RORγt (Th17).

Type 1 diabetes and gut microbiota: Friend or foe?

Type 1 diabetes is a T cell-mediated autoimmune disease. Environmental factors play an important role in the initiation of the disease in genetically predisposed individuals. With the improved control of infectious disease, the incidence of autoimmune diseases, particularly type 1 diabetes, has dramatically increased in developed countries. Increasing evidence suggests that gut microbiota are involved in the pathogenesis of type 1 diabetes. Here we focus on recent advances in this field and provide a rationale for novel therapeutic strategies targeting gut microbiota for the prevention 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.

Effect of dietary gluten on dendritic cells and innate immune subsets in BALB/c and NOD mice

The innate immune system is known to play an important role in oral tolerance to dietary antigens. This is important in development of celiac disease (CD) but may also be important in type 1 diabetes (T1D), and could potentially explain the reduced incidence of T1D in mice receiving a gluten-free (GF) diet. The direct in vivo effect of gluten on innate cells, and particularly dendritic cells (DC) is not sufficiently clarified. Therefore, we wished to investigate the innate cell populations of spontaneous diabetic NOD mice and healthy BALB/c mice kept on a GF or a standard (STD) gluten containing diet. We studied, by flow cytometry and reverse transcription-quantitative polymerase chain reaction (qRT-PCR), if dietary gluten induces changes in the activation of DCs and distribution of selected innate cells in lymphoid, pancreatic and intestinal tissues in BALB/c and NOD mice. We found that a GF diet increased the percentage of macrophages in BALB/c spleen and of CD11c⁺ DCs in BALB/c and NOD spleen. Strictly gluten-free (SGF) diet increased the percentage of CD103⁺ DCs in BALB/c mice and decreased percentages of CD11b⁺ DCs in mesenteric and pancreatic lymph nodes in BALB/c mice. SGF diet in BALB/c mice also decreased DC expression of CD40, CCR7 and MHC-II in pancreatic lymph nodes. In conclusion, GF diet changes the composition of the innate immune system in BALB/c and NOD mice and increases expression of DC activation markers in NOD mice. These results contribute to the explanation of the low diabetes incidence in GF NOD mice. This mechanism may be important in development of type 1 diabetes, celiac disease and non-celiac gluten sensitivity.

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 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.

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.

Genetic dissection of Iddm26 in the spontaneously diabetic BBDP rat

The 40 Mb T1D susceptibility locus Iddm26 was mapped to chromosome 2 through linkage analysis of a conditioned cross-intercross between the diabetes-prone BBDP and the diabetes-resistant ACI.BBDP-Iddm1,Iddm2 (ACI.1u.Lyp). It is flanked by Iddm32 and Iddm33, which control the kinetics of disease progression. To fine-map Iddm26 and characterize immune phenotypes controlled by this locus, several congenic sublines were generated carrying smaller, overlapping intervals spanning Iddm26 and fragments of Iddm32 and 33. Analysis of disease susceptibility, age of disease onset, and immune phenotypes in these sublines identified subloci regulating these different parameters. Two ACI.1u.Lyp-derived subloci, Iddm26.1 and Iddm26.2, imparted significant protection from diabetes, decreasing the cumulative incidence by as much as 57% and 28%, respectively. Iddm26.2, which overlaps with the human PTPN22 locus, only affected disease susceptibility, whereas Iddm26.1 also significantly affected disease kinetics, delaying T1D onset by more than 10 days compared with the parental BBDP strain. These Iddm26 subloci also regulated various immune phenotypes, including the proportion of splenic macrophages by Iddm26.1, and the proportion of activated T-cells in secondary lymphoid organs by Iddm26.2. The analysis of Iddm26 congenic animals in two different SPF facilities demonstrated that the influence of this locus on T1D is environment-dependent.

Gliadin fragments and a specific gliadin 33-mer peptide close KATP channels and induce insulin secretion in INS-1E cells and rat islets of langerhans

In non-obese diabetic (NOD) mice, diabetes incidence is reduced by a gluten-free diet. Gluten peptides, such as the compound gliadin, can cross the intestinal barrier and may directly affect pancreatic beta cells. We investigated the effects of enzymatically-digested gliadin in NOD mice, INS-1E cells and rat islets. Six injections of gliadin digest in 6-week-old NOD mice did not affect diabetes development, but increased weight gain (20% increase by day 100). In INS-1E cells, incubation with gliadin digest induced a dose-dependent increase in insulin secretion, up to 2.5-fold after 24 hours. A similar effect was observed in isolated rat islets (1.6-fold increase). In INS-1E cells, diazoxide reduced the stimulatory effect of gliadin digest. Additionally, gliadin digest was shown to decrease current through K_ATP-channels. A specific gliadin 33-mer had a similar effect, both on current and insulin secretion. Finally, INS-1E incubation with gliadin digest potentiated palmitate-induced insulin secretion by 13% compared to controls. Our data suggest that gliadin fragments may contribute to the beta-cell hyperactivity observed prior to the development of type 1 diabetes.

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.

Customizing laboratory mice by modifying gut microbiota and host immunity in an early "window of opportunity"

We recently investigated how post-natal microbial gut colonization is important for the development of the immune system, especially in the systemic compartments. This addendum presents additional data which in accordance with our previous findings show that early life microbial colonization is critical for a fine-tuned immune homeostasis to develop also in the intestinal environment. A generalized reduction in the expression of immune signaling related genes in the small intestine may explain previously shown increased systemic adaptive immune reactivity, if the regulatory cross-talk between intra- and extra-intestinal immune cells is immature following a neonatal germ-free period. These findings are furthermore discussed in the context of recently published results on how lack of microbial exposure in the neonatal life modifies disease expression in rodents used as models mimicking human inflammatory diseases. In particular, with a focus on how these interesting findings could be used to optimize the use of rodent models.

Dietary gluten alters the balance of pro-inflammatory and anti-inflammatory cytokines in T cells of BALB/c mice

Several studies have documented that dietary modifications influence the development of type 1 diabetes. However, little is known about the interplay of dietary components and the penetration of diabetes incidence. In this study we tested if wheat gluten is able to induce differences in the cytokine pattern of Foxp3(+) regulatory T cells, as well as Foxp3(-) T cells, isolated from intestinal mucosal lymphoid tissue and non-mucosal lymphoid compartments in BALB/c mice. The gluten-containing standard diet markedly changed the cytokine expression within Foxp3(-) T cells, in all lymphoid organs tested, towards a higher expression of pro-inflammatory interferon-γ (IFN-γ), interleukin-17 (IL-17) and IL-2. In Foxp3(+) regulatory T cells, gluten ingestion resulted in a mucosal increase in IL-17 and IL-2 and an overall increase in IFN-γ and IL-4. The gluten-free diet induced an anti-inflammatory cytokine profile with higher proportion of transforming growth factor-β (TGF-β)(+) Foxp3(-) T cells in all tested lymphoid tissues and higher IL-10 expression within non-T cells in spleen, and a tendency towards a mucosal increase in TGF-β(+) Foxp3(+) regulatory T cells. Our data shows that the gluten-containing standard diet modifies the cytokine pattern of both Foxp3(-) T cells and Foxp3(+) regulatory T cells towards a more inflammatory cytokine profile. This immune profile may contribute to the higher type 1 diabetes incidence associated with gluten intake.

Oral tolerance and OVA-induced tolerogenic dendritic cells reduce the severity of collagen/ovalbumin-induced arthritis in mice

Dietary proteins play an important role in the regulation of systemic immune response, in a phenomenon known as oral tolerance (OT). To evaluate the effects of OT on a murine model of type II collagen (CII) plus ovalbumin (OVA)-induced arthritis (CIA), mice were fed with OVA either before or after CIA induction. OT significantly reduced the paw edema and synovial inflammation, as well as serum levels of anti-CII, the ex vivo proliferation and inflammatory cytokine production by spleen cells from CIA mice. The frequencies of Foxp3(+) and IL-10(+) cells were higher, whereas IFNγ(+) cells and IL-17(+) cells were lower, among gated CD4(+) spleen T cells from tolerized CIA mice than in those from non-tolerized CIA mice. Adoptive transfer of tolerogenic dendritic cells (DCs) before CIA induction mimics the effects observed in the OT. We demonstrate here that bystander suppression induced by OT can modify the course of CIA and tolerogenic DCs play a role this phenomenon.

Early life treatment with vancomycin propagates Akkermansia muciniphila and reduces diabetes incidence in the NOD mouse

AIMS/HYPOTHESIS

Increasing evidence suggests that environmental factors changing the normal colonisation pattern in the gut strongly influence the risk of developing autoimmune diabetes. The aim of this study was to investigate, both during infancy and adulthood, whether treatment with vancomycin, a glycopeptide antibiotic specifically directed against Gram-positive bacteria, could influence immune homeostasis and the development of diabetic symptoms in the NOD mouse model for diabetes.

METHODS

Accordingly, one group of mice received vancomycin from birth until weaning (day 28), while another group received vancomycin from 8 weeks of age until onset of diabetes. Pyrosequencing of the gut microbiota and flow cytometry of intestinal immune cells was used to investigate the effect of vancomycin treatment.

RESULTS

At the end of the study, the cumulative diabetes incidence was found to be significantly lower for the neonatally treated group compared with the untreated group, whereas the insulitis score and blood glucose levels were significantly lower for the mice treated as adults compared with the other groups. Mucosal inflammation was investigated by intracellular cytokine staining of the small intestinal lymphocytes, which displayed an increase in cluster of differentiation (CD)4(+) T cells producing pro-inflammatory cytokines in the neonatally treated mice. Furthermore, bacteriological examination of the gut microbiota composition by pyrosequencing revealed that vancomycin depleted many major genera of Gram-positive and Gram-negative microbes while, interestingly, one single species, Akkermansia muciniphila, became dominant.

CONCLUSIONS/INTERPRETATION

The early postnatal period is a critical time for microbial protection from type 1 diabetes and it is suggested that the mucolytic bacterium A. muciniphila plays a protective role in autoimmune diabetes development, particularly during infancy.

Animal models to study gluten sensitivity

The initial development and maintenance of tolerance to dietary antigens is a complex process that, when prevented or interrupted, can lead to human disease. Understanding the mechanisms by which tolerance to specific dietary antigens is attained and maintained is crucial to our understanding of the pathogenesis of diseases related to intolerance of specific dietary antigens. Two diseases that are the result of intolerance to a dietary antigen are celiac disease (CD) and dermatitis herpetiformis (DH). Both of these diseases are dependent upon the ingestion of gluten (the protein fraction of wheat, rye, and barley) and manifest in the gastrointestinal tract and skin, respectively. These gluten-sensitive diseases are two examples of how devastating abnormal immune responses to a ubiquitous food can be. The well-recognized risk genotype for both is conferred by either of the HLA class II molecules DQ2 or DQ8. However, only a minority of individuals who carry these molecules will develop either disease. Also of interest is that the age at diagnosis can range from infancy to 70-80 years of age. This would indicate that intolerance to gluten may potentially be the result of two different phenomena. The first would be that, for various reasons, tolerance to gluten never developed in certain individuals, but that for other individuals, prior tolerance to gluten was lost at some point after childhood. Of recent interest is the concept of non-celiac gluten sensitivity, which manifests as chronic digestive or neurologic symptoms due to gluten, but through mechanisms that remain to be elucidated. This review will address how animal models of gluten-sensitive disorders have substantially contributed to a better understanding of how gluten intolerance can arise and cause disease.

Remission without insulin therapy on gluten-free diet in a 6-year old boy with type 1 diabetes mellitus

A 5-year and 10-month old boy was diagnosed with classical type 1 diabetes mellitus (T1DM) without celiac disease. He started on a gluten-free diet after 2-3 week without need of insulin treatment. At the initiation of gluten-free diet, HbA1c was 7.8% and was stabilised at 5.8%-6.0% without insulin therapy. Fasting blood glucose was maintained at 4.0-5.0 mmol/l. At 16 months after diagnosis the fasting blood glucose was 4.1 mmol/l and after 20 months he is still without daily insulin therapy. There was no alteration in glutamic acid decarboxylase positivity. The gluten-free diet was safe and without side effects. The authors propose that the gluten-free diet has prolonged remission in this patient with T1DM and that further trials are indicated.

Patterns of early gut colonization shape future immune responses of the host

The most important trigger for immune system development is the exposure to microbial components immediately after birth. Moreover, targeted manipulation of the microbiota can be used to change host susceptibility to immune-mediated diseases. Our aim was to analyze how differences in early gut colonization patterns change the composition of the resident microbiota and future immune system reactivity. Germ-free (GF) mice were either inoculated by single oral gavage of caecal content or let colonized by co-housing with specific pathogen-free (SPF) mice at different time points in the postnatal period. The microbiota composition was analyzed by denaturing gradient gel electrophoresis for 16S rRNA gene followed by principal component analysis. Furthermore, immune functions and cytokine concentrations were analyzed using flow cytometry, ELISA or multiplex bead assay. We found that a single oral inoculation of GF mice at three weeks of age permanently changed the gut microbiota composition, which was not possible to achieve at one week of age. Interestingly, the ex-GF mice inoculated at three weeks of age were also the only mice with an increased pro-inflammatory immune response. In contrast, the composition of the gut microbiota of ex-GF mice that were co-housed with SPF mice at different time points was similar to the gut microbiota in the barrier maintained SPF mice. The existence of a short GF postnatal period permanently changed levels of systemic regulatory T cells, NK and NKT cells, and cytokine production. In conclusion, a time window exists that enables the artificial colonization of GF mice by a single oral dose of caecal content, which may modify the future immune phenotype of the host. Moreover, delayed microbial colonization of the gut causes permanent changes in the immune system.

Genistein reduces hyperglycemia and islet cell loss in a high-dosage manner in rats with alloxan-induced pancreatic damage

OBJECTIVES

Elucidate whether genistein (a soy-derived isoflavone) possesses the capacity to alleviate hyperglycemia and minimize islet cell loss after the onset of diabetes and whether the beneficial effect of genistein is dosage dependent.

METHODS

Alloxan-induced diabetic male Sprague-Dawley rats were randomly divided into 5 groups (10 rats per group) and treated with saline, vehicle, and 3 different dosages of genistein by daily gavage. Blood glucose and insulin levels, body weight, and oral glucose tolerance test were assessed; histological changes in pancreatic islets were quantified. In addition, rat islets were isolated, cultured, and exposed to alloxan in the presence or absence of genistein. The survival and the proliferation of islet cells were assessed, and insulin levels in the culture supernatant were measured.

RESULTS

In vivo high-dose (30 mg/kg per day) but not low-dose genistein significantly decreases weight loss, hyperglycemia, and islet cell loss in alloxan-induced diabetic rats, while increasing blood insulin levels and glucose tolerance. In vitro experiments reveal that genistein improves islet cell survival and proliferation and facilitates insulin production after alloxan injury.

CONCLUSIONS

Genistein possesses the capacity to reduce hyperglycemia via minimization of islet cell loss in a dosage-dependent manner (estimating >5-fold than physical intakes) after the onset of diabetes.

Type-specific human papillomavirus detection in cervical smears in Romania

To study type 1 diabetes (T1D), excellent animal models exist, both spontaneously diabetic and virus-induced. Based on knowledge from these, this review focuses on the environmental factors leading to T1D, concentrated into four areas which are: (1) The thymus-dependent immune system: T1D is a T cell driven disease and the beta cells are destroyed in an inflammatory insulitis process. Autoimmunity is breakdown of self-tolerance and the balance between regulator T cells and aggressive effector T cells is disturbed. Inhibition of the T cells (by e.g. anti-CD3 antibody or cyclosporine) will stop the T1D process, even if initiated by virus. Theoretically, the risk from immunotherapy elicits a higher frequency of malignancy. (2) The activity of the beta cells: Resting beta cells display less antigenicity and are less sensitive to immune destruction. Beta-cell rest can be induced by giving insulin externally in metabolic doses or by administering potassium-channel openers. Both procedures prevent T1D in animal models, whereas no good human data exist due to the risk of hypoglycemia. (3) NKT cells: According to the hygiene hypothesis, stimulation of NKT cells by non-pathogen microbes gives rise to less T cell reaction and less autoimmunity. Glycolipids presented by CD1 molecules are central in this stimulation. (4) Importance of the intestine and gliadin intake: Gluten-free diet dramatically inhibits T1D in animal models, and epidemiological data are supportive of such an effect in humans. The mechanisms include less subclinical intestinal inflammation and permeability, and changed composition of bacterial flora, which can also be obtained by intake of probiotics. Gluten-free diet is difficult to implement, and short-term intake has no effect. Regarding the onset of the T1D disease process, slow-acting enterovirus and gliadin deposits are speculated to be etiological in genetically susceptible individuals, followed by the mentioned four pathogenetic factors acting in concert. Neutralization of any one of these factors is capable of stopping T1D development, as lessons are learned from the animal models.

Animal models in diabetes and pregnancy

The worldwide increase in the incidence of diabetes, the increase in type 2 diabetes in women at reproductive ages, and the cross-generation of the intrauterine programming of type 2 diabetes are the bases for the growing interest in the use of experimental diabetic models in order to gain insight into the mechanisms of induction of developmental alterations in maternal diabetes. In this scenario, experimental models that present the most common features of diabetes in pregnancy are highly required. Several important aspects of human diabetic pregnancies such as the increased rates of spontaneous abortions, malformations, fetoplacental impairments, and offspring diseases in later life can be approached by using the appropriate animal models. The purpose of this review is to give a practical and critical guide into the most frequently used experimental models in diabetes and pregnancy, discuss their advantages and limitations, and describe the aspects of diabetes and pregnancy for which these models are thought to be adequate. This review provides a comprehensive view and an extensive analysis of the different models and phenotypes addressed in diabetic animals throughout pregnancy. The review includes an analysis of the surgical, chemical-induced, and genetic experimental models of diabetes and an evaluation of their use to analyze early pregnancy defects, induction of congenital malformations, placental and fetal alterations, and the intrauterine programming of metabolic diseases in the offspring's later life.

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.

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

OBJECTIVE

There is evidence of gut barrier and immune system dysfunction in some patients with type 1 diabetes, possibly linked with exposure to dietary wheat polypeptides (WP). However, questions arise regarding the frequency of abnormal immune responses to wheat and their nature, and it remains unclear whether such responses are diabetes specific.

RESEARCH DESIGN AND METHODS

In type 1 diabetic patients and healthy control subjects, the immune response of peripheral CD3(+) T-cells to WPs, ovalbumin, gliadin, alpha-gliadin 33-mer peptide, tetanus toxoid, and phytohemagglutinin was measured using a carboxyfluorescein diacetate succinimidyl ester (CFSE) proliferation assay. T-helper cell type 1 (Th1), Th2, and Th17 cytokines were analyzed in WP-stimulated peripheral blood mononuclear cell (PBMNC) supernatants, and HLA was analyzed by PCR.

RESULTS

Of 42 patients, 20 displayed increased CD3(+) T-cell proliferation to WPs and were classified as responders; proliferative responses to other dietary antigens were less pronounced. WP-stimulated PBMNCs from patients showed a mixed proinflammatory cytokine response with large amounts of IFN-gamma, IL-17A, and increased TNF. HLA-DQ2, the major celiac disease risk gene, was not significantly different. Nearly all responders carried the diabetes risk gene HLA-DR4. Anti-DR antibodies blocked the WP response and inhibited secretion of Th1 and Th17 cytokines. High amounts of WP-stimulated IL-6 were not blocked.

CONCLUSIONS

T-cell reactivity to WPs was frequently present in type 1 diabetic patients and associated with HLA-DR4 but not HLA-DQ2. The presence of an HLA-DR-restricted Th1 and Th17 response to WPs in a subset of patients indicates a diabetes-related inflammatory state in the gut immune tissues associated with defective oral tolerance and possibly gut barrier dysfunction.

Tight junctions, intestinal permeability, and autoimmunity: celiac disease and type 1 diabetes paradigms

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 celiac disease (CD), an autoimmune enteropathy, and type 1 diabetes (T1D), a hyperglycosaemia caused by a destructive autoimmune process targeting the insulin-producing pancreatic islet cells. Even if environmental factors and genetic susceptibility are clearly involved in the pathogenesis of autoimmunity, for most autoimmune disorders there is no or little knowledge about the causing agent or genetic makeup underlying the disease. In this respect, CD represents a unique autoimmune disorder because a close genetic association with HLA-DQ2 or HLA-DQ8 haplotypes and, more importantly, the environmental trigger (the gliadin fraction of gluten-containing grains wheat, barley, and rye) are known. Conversely, the trigger for autoimmune destruction of pancreatic ss cells in T1D is unclear. Interestingly, recent data suggest that gliadin is also involved in the pathogenesis of T1D. There is growing evidence that increased intestinal permeability plays a pathogenic role in various autoimmune diseases including CD and T1D. Therefore, we hypothesize that besides genetic and environmental factors, loss of intestinal barrier function is necessary to develop autoimmunity. In this review, each of these components will be briefly reviewed.

(Xeno)estrogen regulation of food allergy

Food allergy and other types of allergies are becoming epidemic in both the developed and developing countries. A large amount of information is available in literature that (xeno)estrogens can regulate the immune response in general, and the development of allergy in particular; however, the effect of (xeno)estrogens on food allergy is basically unknown. With increasing use of xenobiotics worldwide, chemicals with estrogenic activity have been accumulating in our environment. This review has summarized the current literature relating to the topic (xeno)estrogen regulation of food allergy. The effect of (xeno)estrogens on enterocytes, proteases for protein hydrolysis, dendritic cells and T-regulatory cells in the gastrointestinal tract has been discussed. Finally, considering the current confusion in literature regarding the effect of phytoestrogen genistein on the immune system, a brief discussion has been included for its effect on T(H)1-T(H)2 polarization, and possibly food allergy in its relation to windows of exposure. Sufficient evidences exist to support the notion that (xeno)estrogens can regulate food allergy, with the developmental periods more sensitive. Further clinical and animal studies are needed to determine the causal relationship between the exposure of (xeno)estrogens and incidence of food allergy, and the underlying mechanisms.

The "perfect storm" for type 1 diabetes: the complex interplay between intestinal microbiota, gut permeability, and mucosal immunity

It is often stated that type 1 diabetes results from a complex interplay between varying degrees of genetic susceptibility and environmental factors. While agreeing with this principal, our desire is that this Perspectives article will highlight another complex interplay potentially associated with this disease involving facets related to the gut, one where individual factors that, upon their interaction with each another, form a "perfect storm" critical to the development of type 1 diabetes. This trio of factors includes an aberrant intestinal microbiota, a "leaky" intestinal mucosal barrier, and altered intestinal immune responsiveness. Studies examining the microecology of the gastrointestinal tract have identified specific microorganisms whose presence appears related (either quantitatively or qualitatively) to disease; in type 1 diabetes, a role for microflora in the pathogenesis of disease has recently been suggested. Increased intestinal permeability has also been observed in animal models of type 1 diabetes as well as in humans with or at increased-risk for the disease. Finally, an altered mucosal immune system has been associated with the disease and is likely a major contributor to the failure to form tolerance, resulting in the autoimmunity that underlies type 1 diabetes. Herein, we discuss the complex interplay between these factors and raise testable hypotheses that form a fertile area for future investigations as to the role of the gut in the pathogenesis and prevention of type 1 diabetes.

Neonatal formula feeding leads to immunological alterations in an animal model of type 1 diabetes

Neonatal diet may influence the development of type 1 diabetes (T1D) in susceptible individuals through an intestinal mucosal inflammatory response, resulting in loss of self-tolerance. We tested the hypothesis that formula feeding during the neonatal period accelerates the development of T1D in diabetes-prone BioBreeding (BBDP) rats through regulation of CD4+CD25+ regulatory T lymphocytes (T(reg)) and anti-inflammatory cytokines. BBDP rat pups fed rat milk substitute (RMS) via a "pup-in-the cup" system were compared with mother-fed (MF) rats. The spleen and thymus were analyzed for Foxp3-expressing CD4+/CD25+ T cells. Multiplex enzyme-linked immunosorbent assays (ELISAs) were performed to measure cytokine-induced neutrophil chemoattractant (CINC), tumor necrosis factor alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin (IL)-4, IL-10, and IL-18. Diabetes-free survival, time of disease onset, and T(reg)/total T lymphocyte ratios were not different. MF pups had higher ileal CINC (p < 0.001) and IL-18 (p = 0.002), but no differences in the liver. There were no differences in ileal cytokine concentrations of 75-d-old rats, but the formula-fed rats had greater liver TNF-alpha (p < 0.001), IFN-gamma, and IL-4 (p < 0.01) and lower IL-10 (p = 0.002) compared with MF animals. Formula versus maternal milk altered the hepatic cytokine profile at 75 d toward an inflammatory pattern but did not result in altered T(reg) cell frequencies or the development of T1D.

Induction of oral tolerance to HSP60 or an HSP60-peptide activates T cell regulation and reduces atherosclerosis

OBJECTIVE

HSP60-specific T cells contribute to the development of the immune responses in atherosclerosis. This can be dampened by regulatory T cells activated via oral tolerance induction, and we explored the effect of oral tolerance induction to HSP60 and the peptide HSP60 (253 to 268) on atherosclerosis.

METHODS AND RESULTS

HSP60 and HSP60 (253 to 268) were administered orally to LDLr(-/-) mice before induction of atherosclerosis and resulted in a significant 80% reduction in plaque size in the carotid arteries and in a 27% reduction in plaque size at the aortic root. Reduction in plaque size correlated with an increase in CD4(+)CD25(+)Foxp3(+) regulatory T cells in several organs and in an increased expression of Foxp3, CD25, and CTLA-4 in atherosclerotic lesions of HSP60-treated mice. The production of interleukin (IL)-10 and transforming growth factor (TGF)-beta by lymph node cells in response to HSP60 was observed after tolerance induction.

CONCLUSIONS

Oral tolerance induction to HSP60 and a small HSP60-peptide leads to an increase in the number of CD4(+)CD25(+)Foxp3(+) regulatory T cells, resulting in a decrease in plaque size as a consequence of increased production of IL-10 and TGF-beta. We conclude that these beneficial results of oral tolerance induction to HSP60 and HSP60 (253 to 268) may provide new therapeutic approaches for the treatment of atherosclerosis.

Inhibition of autoimmune diabetes by oral administration of anti-CD3 monoclonal antibody

Anti-CD3 monoclonal antibody (mAb) has been shown to induce tolerance and to be an effective treatment for diabetes both in animal models and in human trials. We have shown that anti-CD3 mAb given orally is biologically active in the gut and suppresses experimental autoimmune encephalitis by the induction of a regulatory T-cell that expresses latency-associated peptide (LAP) on its surface. In the present study, we investigated the effect of oral anti-CD3 mAb on the prevention of autoimmune diabetes in AKR mice in which the low-dose streptozocin (STZ) model induces autoimmunity to the beta-cells of the islets. We found that oral anti-CD3 mAb given at doses of 50 and 250 microg/feeding suppressed the incidence of diabetes in this model with the best effects seen at the 50 microg/dose. Associated with suppression, we observed decreased cell proliferation in the spleen and conversion of T-helper (Th)1 responses into Th2/Th3 responses in the periphery, including the pancreatic lymph nodes. Oral anti-CD3 mAb increased the expression of LAP on CD4(+) T-cells, and these cells could adoptively transfer protection. Protection by oral anti-CD3 was transforming growth factor-beta dependent. Our results demonstrate that oral anti-CD3 is effective in the model of STZ-induced diabetes and may be a useful form of therapy for type 1 diabetes in humans.

Glucose in vaginal secretions before and after oral glucose tolerance testing in women with and without recurrent vulvovaginal candidiasis

OBJECTIVE

To measure the change of glucose in vaginal secretions during glucose tolerance testing in women with recurrent vulvovaginal candidiasis and in healthy control subjects.

METHODS

Thirty-eight women with recurrent vulvovaginal candidiasis and 45 healthy, age-matched controls completed a health questionnaire regarding general and gynecologic health and food and alcohol habits. They all underwent an oral glucose tolerance test and a vaginal examination. Vaginal secretion was collected from the proximal part of the vagina. Glucose in plasma and in vaginal secretions were measured at fasting and after 2 hours and analyzed with the hexokinase method. A sample size analysis showed that the number of subjects included in the study was sufficient for a beta value of 0.80, at the significance level of alpha=.05, at a difference in glucose in vaginal secretions of 30% after oral glucose tolerance test.

RESULTS

In healthy women, the median level of glucose in vaginal secretions was 5.2 mM before and 3.7 mM after oral glucose tolerance test, and plasma glucose was 5.0 mM before and 5.8 mM after oral glucose tolerance test. No significant difference was seen regarding change of glucose level in vaginal secretions and plasma glucose after testing, compared with before oral glucose tolerance testing.

CONCLUSION

There were no differences between women with recurrent vulvovaginal candidiasis and control subjects regarding change in glucose level in vaginal secretions or in plasma during oral glucose tolerance test.

LEVEL OF EVIDENCE

II-2.

Induction of oral tolerance to oxidized low-density lipoprotein ameliorates atherosclerosis

BACKGROUND

Oxidation of low-density lipoprotein (LDL) and the subsequent processing of oxidized LDL (oxLDL) by macrophages results in activation of specific T cells, which contributes to the development of atherosclerosis. Oral tolerance induction and the subsequent activation of regulatory T cells may be an adequate therapy for the treatment of atherosclerosis.

METHODS AND RESULTS

Tolerance to oxLDL and malondialdehyde-treated LDL (MDA-LDL) was induced in LDL receptor-/- mice fed a Western-type diet by oral administration of oxLDL or MDA-LDL before the induction of atherogenesis. Oral tolerance to oxLDL resulted in a significant attenuation of the initiation (30% to 71%; P<0.05) and progression (45%; P<0.05) of atherogenesis. Tolerance to oxLDL induced a significant increase in CD4+ CD25+ Foxp3+ cells in spleen and mesenteric lymph nodes, and these cells specifically responded to oxLDL with increased transforming growth factor-beta production. Tolerance to oxLDL also increased the mRNA expression of Foxp3, CTLA-4, and CD25 in the plaque. In contrast, tolerance to MDA-LDL did not affect atherogenesis.

CONCLUSIONS

OxLDL-specific T cells, present in LDL receptor-/- mice and important contributors in the immune response leading to atherosclerotic plaque, can be counteracted by oxLDL-specific CD4+ CD25+ Foxp3+ regulatory T cells activated via oral tolerance induction to oxLDL. We conclude that the induction of oral tolerance to oxLDL may be a promising strategy to modulate the immune response during atherogenesis and a new way to treat atherosclerosis.

Dietary proteins as environmental modifiers of type 1 diabetes mellitus

Type 1 diabetes is an autoimmune disease in which the patient's immune system destroys the insulin-secreting beta-cells in the pancreatic islets of Langerhans. A majority of cases is thought to occur as a result of gene-environment interactions. The identity of the environmental factors remains unknown mainly because of the difficulty in linking past exposures with later disease development. Overall, the data suggest a model in which individuals develop diabetes by several different pathways, each influenced by numerous genetic and environmental variables. The most investigated environmental factors are diet and viruses. In this review, we examine the evidence that the source of dietary proteins can modify diabetes outcome, describe new approaches to identify candidate diabetes-related dietary agents, examine possible links with gut dysfunction, discuss some of the limitations, and propose a multifactorial model for dietary modification of diabetes. The key to diabetes pathogenesis, its prevention, and the ultimate success of beta-cell replacement therapies lies in understanding how the environment controls disease expression. Dietary proteins could be one of these keys.

The responses of lymphocytes from Asian and Caucasian diabetic patients and non-diabetics to hydrogen peroxide and sodium nitrite in the Comet assay

Numerous factors may influence the incidence of diabetes in the population. The production of reactive oxygen species (ROS) is elevated in diabetes patients. Based on the reported involvement of reactive species and nitrate/nitrite in diabetes, this present study has examined in the alkaline Comet assay, the effect of different levels of NaNO(2) in the presence of the oxygen radical generating agent, hydrogen peroxide (H(2)O(2)). Peripheral lymphocytes from diabetic and non-diabetic Caucasians and Asians of both sexes were studied in vitro. Endogenous factors (e.g., sex, age, body mass index-BMI) and exogenous factors (lifestyle factors e.g., smoking and drinking habits, diet) were taken into account. A preliminary study in two individuals showed that DNA damage remained constant over a wide dose range of NaNO(2) (1-75mM), but when H(2)O(2) was added at a constant concentration of 50microM per dose of NaNO(2), there was an increase in DNA damage corresponding with the varying levels of NaNO(2) investigated. This was also seen with the 44 individuals (non-diabetic, n=24; type 1 diabetic, n=11; type 2 diabetic, n=9) investigated. NaNO(2) was capable of inducing a significant level of DNA damage in lymphocytes (p<0.001), but only with the addition of H(2)O(2). When levels of DNA damage were analysed in terms of the different variables there were few significant differences in damage between diabetic and non-diabetic subjects, or other sub-population groups, and no statistically significant differences in susceptibility were observed between subject covariates using regression techniques.

NICHD: AAP workshop on neonatology research and training areas of research in neonatal gastroenterology

Future research in neonatal and developmental gastroenterology should include inquiry well beyond finding a cure or better preventative measures against necrotizing enterocolitis. The gastrointestinal (GI) tract acts not only as a digestive-absorptive organ; it also serves major endocrine and neural functions. It encompasses a vast surface area exposed to the external environment and plays a major role in both innate and adaptive immunity. Numerous short- and long-term health benefits could be derived from a better understanding of the developing GI tract.