Milk proteins in the etiology of insulin-dependent diabetes mellitus (IDDM)

Prediction and Prevention of Type 1 Diabetes

Type 1 Diabetes (T1D) is one of the most common chronic autoimmune diseases in children. The disease is characterized by the destruction of beta cells, leading to hyperglycemia, and to a lifelong insulin-dependent state. Although several studies in the last decades have added relevant insights, the complex pathogenesis of the disease is not yet completely understood. Recent studies have been focused on several factors, including family history and genetic predisposition (HLA and non-HLA genes) as well as environmental and metabolic biomarkers, with the aim of predicting the development and progression of T1D. Once a child becomes symptomatic, beta cell mass has already reached a critical threshold (usually a residual of 20-30% of normal amounts), thus representing only the very late phase of the disease. In particular, this final stage follows two preceding asymptomatic stages, which have been precisely identified. In view of the long natural history and complex pathogenesis of the disease, many strategies may be proposed for primary, secondary, and tertiary prevention. Strategies of primary prevention aim to prevent the onset of autoimmunity against beta cells in asymptomatic individuals at high risk for T1D. In addition, the availability of novel humoral and metabolic biomarkers that are able to characterize subjects at high risk of progression, have stimulated several studies on secondary and tertiary prevention, aimed to preserve residual beta cell destruction and/or to prolong the remission phase after the onset of T1D. This review focuses on the major current knowledge on prediction and prevention of T1D in children.

Is there a role for gut microbiota in type 1 diabetes pathogenesis?

Type 1 diabetes mellitus (T1D) is an autoimmune disease characterized by insufficient insulin production due to the destruction of insulin secreting β-cells in the Langerhans islets. A variety of factors, including chemicals, viruses, commensal bacteria and diet have been proposed to contribute to the risk of developing the disorder. In the last years, gut microbiota has been proposed as a main factor in T1D pathogenesis. Several alterations of gut microbiota composition were described both in animal model and in humans. The decrease of Firmicutes/Bacteroides ratio was the most frequent pattern described, in particular, in human studies. Furthermore, Bacteroides, Clostridium cluster XIVa, Lactobacillus, Bifidobacterium, and Prevotella relative abundances were different in healthy and affected subjects. Dysbiosis would seem to increase intestinal permeability and thus promote the development of a pro-inflammatory niche that stimulates β-cell autoimmunity in predisposed subjects. Preliminary studies on animal models were realized to investigate the role of gut microbiota modulation as therapy or prevention approach in predisposed animals: promising and stimulating results have been reported. Key message Dietary antigens and microbiota-derived products might act as triggers of T1D by causing a pro-inflammatory and metabolic dysfunctional environment.

Role of nutritional factors at the early life stages in the pathogenesis and clinical course of type 1 diabetes

Nutrition has been suggested as an important environmental factor other than viruses and chemicals in the pathogenesis of type 1 diabetes (T1D). Whereas various maternal dietary nutritional elements have been suggested and examined in T1D of both humans and experimental animals, the results largely remain controversial. In a series of studies using T1D model nonobese diabetic (NOD) mice, maternal dietary n-6/n-3 essential fatty acid ratio during pregnancy and lactation period, that is, early life stages of the offspring, has been shown to affect pathogenesis of insulitis and strongly prevent overt T1D of the offspring, which is consistent with its preventive effects on other allergic diseases.

Immunobiology of beta-cell destruction

Type 1 diabetes is a chronic disease characterized by severe insulin deficiency and hyperglycemia, due to autoimmune destruction of pancreatic islets of Langerhans. A susceptible genetic background is necessary, but not sufficient, for the development of the disease. Epidemiological and clinical observations underscore the importance of environmental factors as triggers of type 1 diabetes, currently under investigation. Islet-specific autoantibodies precede clinical onset by months to years and are established tools for risk prediction, yet minor players in the pathogenesis of the disease. Many efforts have been made to elucidate disease-relevant defects in the key immune effectors of islet destruction, from the early failure of specific tolerance to the vicious circle of destructive insulitis. However, the events triggering islet autoimmunity as well as the transition to overt diabetes are still largely unknown, making prevention and treatment strategies still a challenge.

Potential mechanisms explaining why hydrolyzed casein-based diets outclass single amino acid-based diets in the prevention of autoimmune diabetes in diabetes-prone BB rats

BACKGROUND

It remains controversial whether avoidance of dietary diabetogenic triggers, such as cow's milk proteins, can prevent type 1 diabetes in genetically susceptible individuals. Here, different extensive casein hydrolysates (HC) and single amino acid (AA) formulations were tested for their effect on mechanisms underlying autoimmune diabetes pathogenesis in diabetes-prone BioBreeding rats. Intestinal integrity, gut microbiota composition and mucosal immune reactivity were studies to assess whether these formulations have differential effects in autoimmune diabetes prevention.

METHODS

Diabetes-prone BioBreeding rats received diets in which the protein fraction was exchanged for the different hydrolysates or AA compositions, starting from weaning until the end of the experiment (d150). Diabetes development was monitored, and faecal and ileal samples were collected. Gut microbiota composition and cytokine/tight junction mRNA expression were measured by quantitative polymerase chain reaction. Cytokine levels of ileum explant cultures were measured by ELISA, and intestinal permeability was measured in vivo by lactulose-mannitol assay.

RESULTS

Both HC-diet fed groups revealed remarkable reduction of diabetes incidence with the most pronounced effect in Nutramigen®-fed animals. Interestingly, AA-fed rats only showed delayed autoimmune diabetes development. Furthermore, both HC-fed groups had improved intestinal barrier function when compared with control chow or AA-fed animals. Interestingly, higher IL-10 levels were measured in ileum tissue explants from Nutramigen®-fed rats. Beneficial gut microbiota changes (increased Lactobacilli and reduced Bacteroides spp. levels) were found associated especially with HC-diet interventions.

CONCLUSIONS

Casein hydrolysates were found superior to AA-mix in autoimmune diabetes prevention. This suggests the presence of specific peptides that beneficially affect mechanisms that may play a critical role in autoimmune diabetes pathogenesis.

Do the interactions between glucocorticoids and sex hormones regulate the development of the metabolic syndrome?

The metabolic syndrome is basically a maturity-onset disease. Typically, its manifestations begin to flourish years after the initial dietary or environmental aggression began. Since most hormonal, metabolic, or defense responses are practically immediate, the procrastinated response do not seem justified. Only in childhood, the damages of the metabolic syndrome appear with minimal delay. Sex affects the incidence of the metabolic syndrome, but this is more an effect of timing than absolute gender differences, females holding better than males up to menopause, when the differences between sexes tend to disappear. The metabolic syndrome is related to an immune response, countered by a permanent increase in glucocorticoids, which keep the immune system at bay but also induce insulin resistance, alter the lipid metabolism, favor fat deposition, mobilize protein, and decrease androgen synthesis. Androgens limit the operation of glucocorticoids, which is also partly blocked by estrogens, since they decrease inflammation (which enhances glucocorticoid release). These facts suggest that the appearance of the metabolic syndrome symptoms depends on the strength (i.e., levels) of androgens and estrogens. The predominance of glucocorticoids and the full manifestation of the syndrome in men are favored by decreased androgen activity. Low androgens can be found in infancy, maturity, advanced age, or because of their inhibition by glucocorticoids (inflammation, stress, medical treatment). Estrogens decrease inflammation and reduce the glucocorticoid response. Low estrogen (infancy, menopause) again allow the predominance of glucocorticoids and the manifestation of the metabolic syndrome. It is postulated that the equilibrium between sex hormones and glucocorticoids may be a critical element in the timing of the manifestation of metabolic syndrome-related pathologies.

Surface Plasmon Resonance imaging-based sensing for anti-bovine immunoglobulins detection in human milk and serum

Only few papers deal with Surface Plasmon Resonance imaging (SPRi) direct detection on complex matrices, limiting the biosensor application to real analytical problems. In this work a SPRi biosensor for anti-bovine IgG detection in untreated human bodily fluids, i.e. diluted human serum and milk, was developed. Enhanced levels of cow's milk antibodies in children's serum are suspected for their possible correlation with Type 1 diabetes during childhood and their detection in real samples was up to now performed by classical immunoassays based on indirect detection. The biosensor was optimised in standard samples and then in untreated human milk for anti-bovine IgG direct detection. The key novelty of the work is the evaluation of matrix effect by applying to real samples an experimental and ex ante method previously developed for SPRi signal sampling in standard solutions, called "Data Analyzer"; it punctually visualises and analyses the behaviour of receptor spots of the array, to select only spot areas with the best specific vs. unspecific signal values. In this way, benefits provide by SPRi image analysis are exploited here to quantify and minimise drawbacks due to the matrix effect, allowing to by-pass every matrix pre-treatment except dilution.

Immunology of beta-cell destruction

The pancreatic islet beta-cells are the target for an autoimmune process that eventually results in an inability to control blood glucose due to the lack of insulin. The different steps that eventually lead to the complete loss of the beta-cells are reviewed to include the very first step of a triggering event that initiates the development of beta-cell autoimmunity to the last step of appearance of islet-cell autoantibodies, which may mark that insulitis is about to form. The observations that the initial beta-cell destruction by virus or other environmental factors triggers islet autoimmunity not in the islets but in the draining pancreatic lymph nodes are reviewed along with possible basic mechanisms of loss of tolerance to islet autoantigens. Once islet autoimmunity is established the question is how beta-cells are progressively killed by autoreactive lymphocytes which eventually results in chronic insulitis. Many of these series of events have been dissected in spontaneously diabetic mice or rats, but controlled clinical trials have shown that rodent observations are not always translated into mechanisms in humans. Attempts are therefore needed to clarify the step 1 triggering mechanisms and the step to chronic autoimmune insulitis to develop evidence-based treatment approaches to prevent type 1 diabetes.

Review series on helminths, immune modulation and the hygiene hypothesis: how might infection modulate the onset of type 1 diabetes?

The development of type 1 diabetes is influenced by both genetic and environmental factors. The current rise in the incidence of diabetes is occurring more rapidly than can be accounted for by genetic change, highlighting the influence of environmental modifiers. Considerable effort has been expended to identify infectious agents that might be responsible for this rise in incidence, but no single infectious agent has been linked to this dramatic increase in type 1 diabetes. There has been increasing interest in the possibility that infections of historical importance that might have shaped our immune systems over evolutionary time may also have played a role in down-modulating some autoimmune and allergic disorders. In this review, some of the ways in which certain organisms might have influenced the onset of autoimmunity are discussed.

The stages of type 1A diabetes

We can now predict the development of type 1 diabetes in man because it is a chronic autoimmune disorder with defined stages of disease. We can also readily prevent the disorder in animal models. A major goal is safe prevention in man, and for this we will almost certainly need a better understanding of pathogenesis, coupled with rigorous clinical trials.

Genes mediating environment interactions in type 1 diabetes

The relative risk of type 1 (autoimmune) diabetes mellitus for a sibling of an affected patient is fifteen times that of the general population, indicating a strong genetic contribution to the disease. Yet, the incidence of diabetes in most Western communities has doubled every fifteen years since the Second World War - a rate of increase that can only possibly be explained by a major etiological effect of environment. Here, the authors provide a selective review of risk factors identified to date. Recent reports of linkage of type 1 diabetes to genes encoding pathogen pattern recognition molecules, such as toll-like receptors, are discussed, providing a testable hypothesis regarding a mechanism by which genetic and environmental influences on disease progress are integrated.

Type 1 diabetes mellitus: etiology, presentation, and management

This article reviews our current understanding of the etiology, presentation, and management of type 1 diabetes. The discussion includes a review of the natural history of diabetes, the complex relationship between genetic and environmental risk for type 1 diabetes, and current methods for prediction of type 1 diabetes. The article also reviews the current management of children who have new-onset type 1 diabetes, age-appropriate management goals, and diabetes complications. Finally, the article discusses the future of diabetes screening programs and the progress toward the ultimate goal of curing type 1 diabetes.

Natural history of type 1 diabetes

The natural history of autoimmune type 1 diabetes in children is associated with the appearance of islet autoantibodies early in life, which is influenced by genetic and environmental factors. Once islet autoantibodies have developed, the progression to diabetes in antibody-positive individuals is determined by the age of antibody appearance and by the magnitude of the autoimmunity, in turn related to the age of the subject. Characteristics that describe the magnitude of the autoimmunity can stage progression to type 1 diabetes in islet autoantibody-positive subjects regardless of genetic background or age.

Epidemiological association between some dietary habits and the increasing incidence of type 1 diabetes worldwide

BACKGROUND/AIMS

The variation in incidence of type 1 diabetes (T1D) worldwide is genetically based. However, its increasing incidence is environmentally determined. Our aim was to describe the role of nutritional habits and of gene-nutrient interactions in the rising incidence of TID.

METHODS

We did an ecological study in the 37 world areas were a 3% yearly increase of T1D incidence had been reported, and we calculated through the FAO's Food Balance Sheets the per caput daily supply of milk, meat and cereals from 1961 to 2000 and its correlation with the TID incidence.

RESULTS

The supply of milk and cereals remained almost unchanged, whereas that of meat increased by over 31%. The absolute mean TID increase (number of cases per 100,000 per year) was + 0.32. A significant positive correlation with supply of milk was present from 1961 to 2000, while that with meat and cereals became significant in 1983 and 2000.

CONCLUSION

Our ecological analysis indicates that nutritional factors, and in particular meat consumption, play a role in the incidence of T1D and its increase worldwide. Further experimental and case-control studies are warranted in order to assess the gene-nutrient interactions.

ADA Outstanding Scientific Achievement Lecture 2004. Thirty years of investigating the autoimmune basis for type 1 diabetes: why can't we prevent or reverse this disease?

Thirty years ago, a convergence of investigational observations lead to the now widely accepted notion that type 1 diabetes results from an autoimmune destruction of insulin-producing beta-cells in subjects genetically predisposed to the disease. Improvements in understanding of the natural history of type 1 diabetes, the biochemical identification of autoantigens, the discovery of spontaneous animal models for the disease, the availability of immune-modulating agents, and other important facets, including disease prediction, drove an early sense of optimism that the prevention of type 1 diabetes was possible and, in some research circles, that ability was thought to be within a not-to-distant reach. Unfortunately, those early expectations proved overly optimistic, and despite the aforementioned knowledge gains, the generation of improved investigational tools, the identification of methods to prevent the disease in animal models, and the formation of very large disease prevention trials, a means to prevent type 1 diabetes in humans continues to remain elusive. Believing in the concept of "informative failures" (a.k.a., wise people learn from their mistakes), this lecture reviews the knowledge base collected over this time period and, when combined with an analysis of those research experiences, sets forth a proposal for future investigations that will, hopefully, turn discoveries into a means for the prevention or reversal of type 1 diabetes.

Infant diet and type 1 diabetes in China

Infant milk and food introduction may be linked to type 1 diabetes risk in high incidence populations. Dietary data through age 12 months was collected for 247 type 1 diabetic cases and 443 controls in China, a low incidence population, to determine if milk and solid food intake differed. Age range at introduction to milk and formulas was similar in cases and controls but solid food introduction more often occurred before age 3 months in cases. Logistic regression analyses showed soy milk formula consumption at 4-6 (OR = 2.0; 95% CI: 1.1-3.4) and 7-12 months of age (OR = 1.5; 95% CI: 1.0-2.1) was associated with a twofold higher risk of type 1 diabetes, while steamed bread consumption (4-6 months, OR = 0.44; 95% CI: 0.28-0.68; 7-12 months, OR = 0.48; 95% CI: 0.34-0.69) and higher SES (4-6 months, OR = 0.55; 95% CI: 0.39-0.78; 7-12 months, OR = 0.57; 95% CI: 0.40-0.83) were negatively associated. Drinking cow's milk at 7-12 months (OR = 0.60; 95% CI: 0.43-0.85) was negatively associated with type 1 diabetes while consuming vegetables at 4-6 months (OR = 1.5; 95% CI: 1.0-2.2) was positively associated. Results suggest that infant milk and solid food intake are associated with type 1 diabetes in China. Prospective studies may determine how these dietary factors impact disease etiology, particularly for at-risk-populations.

Increased levels of bovine serum albumin antibodies in patients with type 1 diabetes and celiac disease-related antibodies

OBJECTIVES

To detect the presence of antibodies against bovine serum albumin in a cohort of Spanish patients with type 1 insulin-dependent diabetes.

METHODS

Antibodies were measured using an in-house enzyme-linked immunosorbent assay test in 80 patients with type 1 diabetes, subdivided according to the presence or absence in their serum of celiac disease-related antibodies. For comparison, 30 patients with celiac disease (nondiabetic), 13 patients with autoimmune thyroiditis, and 45 healthy volunteers were used.

RESULTS

Thirty-one percent of patients with diabetes yielded a positive result, with a mean value of 26.1 +/- 21.8 arbitrary units (AU). If the group was split into those with celiac disease-related antibodies and those lacking them, the percentages were 53% and 25%, respectively, with a mean value of 39.6 +/- 28.4 AU and 22.4 +/- 18.3 AU (P = 0.003), respectively. Seventy-three percent of celiac patients showed bovine serum albumin antibodies with a mean level of 38.8 +/- 27.7 AU, comparable to that of patients with diabetes with celiac antibodies, but higher than the group lacking them (P = 0.001). Although 46% of patients with autoimmune thyroiditis had positive results, the level detected (22.1 +/- 8.7 AU) was significantly lower than that recorded in patients with type 1 diabetes who had celiac disease antibodies (P = 0.04) and celiac patients (P = 0.04). Healthy volunteers showed no antibodies against bovine serum albumin.

CONCLUSIONS

These data suggest that bovine serum albumin antibodies appears in patients with a compromised epithelial permeability, and they reflect a general defect in the process of immunologic tolerance associated with a predisposition to autoimmunity, rather than immunity specific to beta cells.

Translating data from animal models into methods for preventing human autoimmune diabetes mellitus: caveat emptor and primum non nocere

Type 1 diabetes in humans is a serious autoimmune disorder of children that is still poorly understood, unpreventable, and irreversible. Study of its animal models, notably the NOD mouse and BB rat, has generated a wealth of information concerning genetics and immunopathogenesis, but that information has still not altered the way in which we treat children with diabetes. In this review we attempt to identify the most promising avenues of continuing research in these models and the most important issues that must be faced by the designers of human therapies based on the animal dataset.

Infant formula ingestion is associated with the development of diabetes in the BB/Wor rat

The association between early exposure to cow's milk products in infancy and risk for insulin dependent diabetes mellitus (IDDM) is controversial. We examined whether the ingestion of cow's milk-based infant formula altered the expression of the diabetic syndrome in the BB/Wor rat, an animal model of IDDM. Pregnant BB/Wor dams were obtained from the NIH contract colony at the University of Massachusetts and housed under semi-barrier conditions. Rat pups were intubated with 1 to 2 ml of commercially available cow's milk-based infant formula (Enfamil or Nutramigen) or sham intubated (controls) daily from day 12 to day 25 of life. Pups were weaned at day 25 and monitored for glucosuria daily through 120 days of life. All rats including dams consumed a milk-free rat chow and acidified water ad libitum throughout the study. The mean age of disease onset was 4 to 10 days earlier in Nutramigen-fed and Enfamil-fed rats relative to controls (84+/-3, 78+/-2 and 88+/-4 days, respectively); the mean age of disease onset was significantly different between controls and Enfamil-fed animals (p<0.05). At 120 days, 60% (12/20) of control rats developed diabetes versus 100% of animals fed either type of infant formula prior to weaning (15/15:Enfamil-fed; 19/19:Nutramigen-fed) (p<0.05). These data indicate that direct, early ingestion of cow's milk-based formula was related to the expression of diabetes in the BB/Wor rat.

Milk and diabetes

Type 1 diabetes is based on autoimmunity, and its development is in part determined by environmental factors. Among those, milk intake is discussed as playing a pathogenic role. Geographical and temporal relations between type 1 diabetes prevalence and cow's milk consumption have been found in ecological studies. Several case-control studies found a negative correlation between frequency and/or duration of breast-feeding and diabetes, but this was not confirmed by all authors. T-cell and humoral responses related to cow's milk proteins were suggested to trigger diabetes. The different findings of studies in animals and humans as well as the potential underlying mechanisms with regard to single milk proteins (bovine serum albumin, beta-lactoglobulin, casein) are discussed in this review. In contrast to type 1 diabetes, the etiology of type 2 diabetes, characterized by insulin resistance is still unclear. In a population with a high prevalence of type 2 diabetes, the Pima Indians, people who were exclusively breastfed had significantly lower rates of type 2 diabetes than those who were exclusively bottlefed. Studies in lactovegetarians imply that consumption of low fat dairy products is associated with lower incidence and mortality of diabetes and lower blood pressures. In contrast, preference for a diet high in animal fat could be a pathogenic factor, and milk and high fat dairy products contribute considerably to dietary fat intake. Concerning milk fat composition, the opposite effects of various fatty acids (saturated fatty acids, trans-fatty acids, conjugated linoleic acid) in vitro, in animals and in humans have to be considered.

The ABBOS-peptide from bovine serum albumin causes an IFN-gamma and IL-4 mRNA response in lymphocytes from children with recent onset of type 1 diabetes

The ABBOS-peptide from bovine serum albumin (BSA) in cow's milk has been suggested to initiate the autoimmune process against the beta-cells leading to type 1 diabetes. The aim of this study was to elucidate if the ABBOS-peptide is a possible trigger of type I diabetes. The cytokines IL-4 and IFN-gamma were determined at the level of transcription as mRNA in lymphocytes, stimulated with the ABBOS-peptide. Sixteen children with newly diagnosed type 1 diabetes were compared with 10 healthy controls matched for the diabetes associated HLA-type DR3/4. Antibodies to bovine serum albumin (BSA), insulin antibodies (IA), and antibodies against islet cells (ICA) were determined, as well as serum C-peptide. Increased mRNA expression for IFN-gamma and/or IL-4 could be observed in lymphocytes from 13/16 children with recent onset of diabetes after in vitro stimulation with the ABBOS-peptide. Low expression of IFN-gamma mRNA was associated with high secretion of C-peptide, whereas a positive relationship could be observed between expression of IL-4 mRNA and insulin antibodies. Expression of IFN-gamma and/or IL-4 mRNA was also detected in lymphocytes from 6/10 healthy controls. ABBOS may have a role as a reactive epitope in the upregulation of the autoimmune process against the beta-cells but ABBOS does not seem to cause any specific Th1 response. An increased mRNA expression could also be seen in lymphocytes from healthy controls. Thus, the ABBOS-peptide might just cause or reflect an unspecific immune activity.

Cellular and molecular roles of beta cell autoantigens, macrophages and T cells in the pathogenesis of autoimmune diabetes

Type I diabetes, also known as insulin-dependent diabetes mellitus (IDDM) results from the destruction of insulin-producing pancreatic beta cells by a progressive beta cell-specific autoimmune process. The pathogenesis of autoimmune IDDM has been extensively studied for the past two decades using animal models such as the non-obese diabetic (NOD) mouse and the BioBreeding (BB) rat. However, the initial events that trigger the immune responses leading to the selective destruction of the beta cells are poorly understood. It is thought that beta cell autoantigens are involved in the triggering of beta cell-specific autoimmunity. Among a dozen putative beta cell autoantigens, glutamic acid decarboxylase (GAD) has been proposed as perhaps the strongest candidate in both humans and the NOD mouse. In the NOD mouse, GAD, as compared with other beta cell autoantigens, provokes the earliest T cell proliferative response. The suppression of GAD expression in the beta cells results in the prevention of autoimmune diabetes in NOD mice. In addition, the major populations of cells infiltrating the islets during the early stage of insulitis in BB rats and NOD mice are macrophages and dendritic cells. The inactivation of macrophages in NOD mice results in the prevention of T cell mediated autoimmune diabetes. Macrophages are primary contributors to the creation of the immune environment conducive to the development and activation of beta cell-specific Th1-type CD4+ T cells and CD8+ cytotoxic T cells that cause autoimmune diabetes in NOD mice. CD4+ and CD8+ T cells are both believed to be important for the destruction of beta cells. These cells, as final effectors, can kill the insulin-producing beta cells by the induction of apoptosis. In addition, CD8+ cytotoxic T cells release granzyme and cytolysin (perforin), which are also toxic to beta cells. In this way, macrophages, CD4+ T cells and CD8+ T cells act synergistically to kill the beta cells in conjunction with beta cell autoantigens and MHC class I and class II antigens, resulting in the onset of autoimmune type I diabetes.

Aleitamento materno e diabetes Mellitus do tipo 1

OBJETIVOS: Considerando-se os recentes relatos de uma possível relação entre exposição precoce ao leite bovino e diabetes mellitus do tipo 1 (DM1), este estudo teve como objetivo pesquisar a idade de inicio de exposição alimentar ao leite bovino em indivíduos portadores de DM1, através de um estudo caso-controle; bem como correlacionar a idade de introdução do leite bovino na dieta com o desenvolvimento e a idade de aparecimento do DM1. MÉTODOS: O estudo foi baseado em entrevistas dirigidas às mães de indivíduos dos seguintes grupos: a) grupo de pacientes diabéticos insulino-dependentes (GDM1), com diagnóstico realizado até os 30 anos, com média de idade ao diagnóstico de 9,2±5,4 anos; b) grupo controle (GC): estudantes não-diabéticos. A amostra constitui-se de 124 indivíduos (47 do GDM1 e 77 do GC), sem diferença estatística em relação a sexo e idade cronológica entre os dois grupos. RESULTADOS: A média do tempo de aleitamento exclusivo foi significativamente menor para o GDM considerando o sexo feminino. Não houve diferença significante entre as médias dos grupos considerando o sexo masculino. Não houve correlação entre a idade de exposição ao leite bovino e a idade de início do DM1. CONCLUSÕES: Indivíduos com DM1 do sexo feminino foram expostos mais precocemente ao leite bovino comparados aos indivíduos controles, sugerindo um possível papel deste alimento na etiopatogenia da doença. A retirada precoce do leite materno da dieta dos lactentes e, consequentemente, dos fatores de proteção por ele oferecidos, podem ser considerados elementos potencialmente relacionados com o desencadeamento do processo auto-imune.

Anti-BSA antibodies do not cross-react with the 69-kDa islet cell autoantigen ICA69

In contrast to several previously published reports, we demonstrate by a variety of antibody assays that bovine serum albumin (BSA) is not antigenically cross-reactive with the 69-kDa islet cell autoantigen (ICA69). Fast protein liquid chromatography purified BSA and highly purified recombinant human ICA69 were used to establish sensitive Western blot and ELISA assays in order to detect antibodies against these two proteins. The assays excluded BSA or powdered milk as blocking agents, since these would interfere with antibody binding. A panel of sera from diabetic individuals, first degree relatives, and normal controls showed that the majority (approximately 70%) of individuals from each group had antibodies against ICA69 as assayed by Western blots, whereas considerably fewer (approximately 13%) had anti-BSA antibodies on Western blots, and individuals with antibodies to both proteins occurred only rarely (2-3%). To explore this issue further we immunized a total of 16 individual rats, representing four different strains (bio-breeding diabetes resistant and diabetes prone, Wistar-Furth, and Sprague-Dawley), with either BSA (n = 2 of each strain) or with recombinant ICA69 (n = 2 of each strain), and for each animal pre- and postimmune antibody titres against BSA and against ICA69 were assayed separately by enzyme-linked immunoabsorbent assay. In rats immunized with BSA, anti-BSA titres increased about 100,000-fold over preimmune levels, whereas anti-ICA69 reactive antibodies were unchanged over preimmune levels. Similarly, in rats immunized with ICA69, anti-ICA69 titres rose about 100,000-fold over preimmune levels, whereas anti-BSA antibodies were unchanged over preimmune levels. Thus we find no evidence for the existence of antibody cross-reactivity between ICA69 and BSA, either in humans or in immunized rats. When our rat anti-BSA antisera were used to probe Western blots made from rat islets isolated in the strict absence of fetal calf serum, we were unable to detect a 69-kDa band, even when the islets were preincubated with gamma-interferon, a treatment which has been reported to induce the BSA cross-reactive islet antigen. We conclude that BSA is not antigenically cross-reactive with ICA69 at the antibody level, and it is highly unlikely that BSA is antigenically cross-reactive with some other 69 kD islet cell antigen.

Amamentação ao seio, amamentação com leite de vaca e o diabetes mellitus tipo 1: examinando as evidências

A etiologia do diabetes mellitus tipo 1 (DM1) envolve tanto herança genética como a exposição a fatores ambientais. Evidências de estudos epidemiológicos e experimentais sugerem que a dieta pode ser importante na etiopatogenia dessa doença. Em 1984, Borch-Johnsen e col. sugeriram, com base nos resultados de um estudo caso-controle, que o leite materno seria um fator de proteção para o DM1; esse efeito se daria devido às propriedades anti-infecciosas desse tipo de leite, ou pelo fato de que a amamentação ao seio evitaria que as crianças pudessem ser precocemente expostas a outros agentes etiológicos contidos nos substitutos do leite materno. Esses mesmos achados foram poste-riormente encontrados em diversos estudos, mas o papel do leite materno no aparecimento do DM1 ainda permanece controverso. Em 1992, Karjalainen e col., ao compararem os soros de indivíduos com e sem DM1, observaram, entre os diabéticos, altas concentrações de anticorpos anti-albumina bovina. Os autores postularam a hipótese de que a albumina bovina poderia atuar como desencadeadora do processo destrutivo das células ß do pâncreas e, conseqüentemente, do diabetes. Resultados conflitantes foram observados nas publicações que se sucederam a essa. Neste artigo, resumem-se e discutem-se os achados de diferentes pesquisadores que investigaram a importância desses fatores dietéticos para o aparecimento do DM1.

[Reproducibility of data in a study of the risk factors for insulin-dependent diabetes mellitus]

The reliability of information about mothers' and fathers' education, weight and height at birth, history of diarrhoea, duration of exclusive breast feeding and age of introduction of cows' milk products, selected from a structured questionnaire used in home interviewers was examined in a sample of 38 cases and 38 controls from a study related to the risk factors of insulin-dependent diabetes mellitus. The repetition of the questions was done by telephone. The agreement between the answers of both interviewers was verified using the kappa statistic (categorical variables) and the intra-class correlation coefficient (quantitative variables). The results enable one to conclude that the information is reproducible.

ICA69 is expressed equally in the human endocrine and exocrine pancreas

Islet cell autoantigen 69 kDa (ICA69) has been reported as a polypeptide antigen expressed in pancreatic beta cells, and autoimmunity against this antigen has been associated with insulin-dependent diabetes mellitus. We have studied the cell type specificity and ontogeny of ICA69 gene expression in man. The ICA69 gene was expressed in all adult human tissues. The level of expression was three-to five-times higher in the pancreas than in the brain, liver, intestine, kidney, spleen, lung or adrenal glands. Pancreatic ICA69 expression increased with age, adult levels being five times higher than the levels present at 13 weeks of gestation. Total RNA from four separate preparations of isolated human islets revealed levels of ICA69 mRNA similar to those found in the pancreas as a whole, although another islet antigen, glutamic acid decarboxylase 65, was highly enriched in the islets. In situ hybridization and immunohistochemical staining of sections of the fetal and adult pancreas revealed expression of the ICA69 gene and protein throughout the acinar, ductal, and islet tissue, but not in the mesenchyme. Analysis of ICA69 mRNA levels in human cell lines indicated expression in neural, endothelial and epithelial cells, but not in fibroblasts. In conclusion, ICA69, although highest in the pancreas, is widely distributed in other human tissues, excluding connective tissue. Within the human pancreas, ICA69 is not enriched in the islets or in the beta cells.

Relation between antibodies to islet cell antigens, other autoantigens and cow's milk proteins in diabetic children and unaffected siblings at the clinical manifestation of IDDM. The Childhood Diabetes in Finland Study Group

The relation between islet cell specific antibodies, other autoantibodies and antibodies to cow's milk proteins was studied in IDDM and pre-IDDM by analysing islet cell antibodies (ICA), insulin autoantibodies (IAA), anti-nuclear (ANA), anti-reticulin class IgA [ARA(IgA)], smooth muscle, anti-mitochondria, parietal cell (PCA), adrenal and thyroid antibodies and antibodies to cow's milk formula (CMF), beta-lactoglobulin (BLG) and bovine serum albumin (BSA) in a population based study with more than 650 children with newly diagnosed IDDM and more than 550 initially non-diabetic siblings. After adjustment for age a weak association was seen in the diabetic children between IAA and ANA but none between ICA and autoantibodies directed against the other organ-specific or non-organ-specific antigens. There was no significant difference in cow's milk antibodies between diabetic children with and without ICA or IAA. The siblings with ICA had higher CMF (IgA and IgM) antibody levels and BLG (IgA) antibody levels than the remaining siblings, but no such differences were found when comparing IAA-positive and negative siblings. Siblings positive for ICA had PCA more often than did the ICA-negative siblings, whereas siblings positive for both ICA and PCA had increased levels of antibodies against CMF, BLG and BSA. These findings indicate that the humoral islet cell-associated autoimmunity characteristic of recent-onset childhood IDDM is clearly restricted to the islet cells and not directly related to signs of other organ-specific or non-organ-specific autoimmunity. The observation of increased levels of antibodies to cow's milk proteins in siblings positive for ICA suggests that the immune response to cow's milk proteins may be related to the progressive autoimmune process resulting in beta-cell destruction and ultimately in the clinical manifestation of IDDM. Gastrointestinal autoimmune mechanisms may play a role in the pathogenesis of IDDM, and the association observed between combined ICA and PCA positivity and increased levels of antibodies to cow's milk proteins in the siblings implies that there may be an enhanced transfer of nutritional antigens across the gut barrier in these subjects.

Self and non-self antigen in diabetic autoimmunity: molecules and mechanisms

In this article, we have summarized current facts, models and views of the autoimmunity that leads to destruction of insulin-producing beta-cells and consequent Type 1 (insulin-dependent) diabetes mellitus. The presence of strong susceptibility and resistance gene loci distinguishes this condition from other autoimmune disorders, but environmental disease factors must conspire to produce disease. The mapping of most of the genetic risk (or disease resistance) to specific alleles in the major histocompatibility locus (MHC class II) has direct functional implications for our understanding of autoimmunity in diabetes and directly implies that presentation of a likely narrow set of peptides is critical to the development of diabetic autoimmunity. While many core scientific questions remain to be answered, current insight into the disease process is beginning to have direct clinical impact with concerted efforts towards disease prevention or intervention by immunological means. In this process, identification of the critical antigenic epitopes recognized by diabetes-associated T cells has achieved highest priority.

T cells from children with IDDM are sensitized to bovine serum albumin

Epidemiological and experimental evidence suggested that denial of dietary cow milk protein early in life protects genetically susceptible children and animals from insulin-dependent diabetes (IDDM). Bovine serum albumin (BSA) was proposed as a candidate milk-borne mimicry antigen responsible for the diabetogenic cow milk effect. Elevated anti-BSA antibodies have been observed in patients and diabetic rodents, and these antibodies precipitate p69 from islet cell lysates. IDDM is a T cell mediated disorder but efforts to detect BSA-specific T cells in diabetic children have so far failed. We describe here a culture system which allowed the detection of BSA-specific T cells and we mapped this response to the ABBOS peptide (pre-BSA position 152-169) previously identified as a possible mimicry epitope. ABBOS-sensitized T cells were found in 28/31 children with recent onset IDDM but not in non-diabetic controls nor in children with SLE or JRA. T cell proliferative responses declined within the first few years of diabetes diagnosis. Although no effector cell role for BSA/ABBOS specific T lymphocytes has been demonstrated, the presence of BSA peptide-specific T cells strengthens the postulated link between a cow milk protein and IDDM.

No association between anti-bovine serum albumin antibodies and islet cell reactive antibodies in newly diagnosed type 1 diabetic patients

Serological findings have suggested that antibodies (Ab) to bovine serum albumin (BSA-Ab) are associated with type 1 diabetes mellitus. The aim of our study was to evaluate a competitive fluid-phase radioimmunoassay for detecting BSA-Ab using different incubation times and to study a possible association of these BSA-antibodies with autoantibodies (AAb) frequently detected in type 1 diabetic patients. For the overnight incubation time, there was an enormous overlap in the [125I]BSA binding by serum samples between 52 newly diagnosed type 1 diabetic patients (mean [125I]BSA binding 23.6 +/- 17.4%) and 54 healthy blood donors (mean [125I]BSA binding 10.2 +/- 15.7%). By an incubation time of only 3 min the BSA-antibody prevalence was found to be 15.4% (8/52) for type 1 diabetic patients and 3.7% (2/54) for control subjects. However, there was no association between BSA-Ab and type 1 diabetes-associated antibodies as cytoplasmic islet cell antibodies (ICA), or glutamate decarboxylase autoantibodies. Our results confirm that (i) BSA-Ab occur more frequently in newly diagnosed type 1 diabetic patients compared with a healthy control group and (ii) that the BSA-Ab detected by the fluid-phase radioimmunoassay with an incubation time of 3 min are more disease-associated than the [125I]BSA binding after an overnight incubation. The competitive BSA-Ab fluid-phase radioimmunoassay described is a simple and rapid method to detect antibodies specifically reactive with BSA. It is suggested that the humoral immune reactivity to BSA in type 1 diabetic patients probably reflects an unspecific defect of the immune system and gives no additionally diagnostic value about the type 1 diabetes.

Lack of immune responsiveness to bovine serum albumin in insulin-dependent diabetes

BACKGROUND

Epidemiologic studies have implicated the ingestion of cow's milk in the pathogenesis of insulin-dependent diabetes mellitus (IDDM). Moreover, in a recent study, 100 percent of patients with new-onset IDDM had antibodies against bovine serum albumin (BSA), with a majority directed against a 17-amino-acid BSA peptide (ABBOS). Cellular immune mechanisms are thought to be the principal mediators of pancreatic beta-cell destruction in IDDM.

METHODS

We measured the responses of peripheral-blood mononuclear cells to BSA and ABBOS or serum IgG anti-BSA antibodies (by particle-concentration fluorescence immunoassay) in 71 patients with IDDM, 55 subjects at various degrees of risk for IDDM, 36 patients with other autoimmune disorders (chronic autoimmune thyroiditis, rheumatoid arthritis, and systemic lupus erythematosus), and 48 normal subjects.

RESULTS

The responses of peripheral-blood mononuclear cells to BSA or ABBOS were positive in 2 of 24 patients with new-onset IDDM, 1 of 25 first-degree relatives of patients with IDDM who were negative for islet-cell antibodies, 2 of 30 first-degree relatives of patients with IDDM who were positive for islet-cell antibodies, 1 of 28 patients with established IDDM, and 1 of 29 normal subjects. Similarly, anti-BSA antibodies were not detected significantly more often in patients with new-onset IDDM (3 of 31, 10 percent) than in normal subjects (1 of 37, 3 percent; P = 0.32). However, many patients with autoimmune disease and subjects at increased risk for IDDM had anti-BSA antibodies (frequency, 10 to 31 percent).

CONCLUSIONS

Anti-BSA antibodies may reflect a general defect in the process of immunologic tolerance associated with a predisposition to autoimmunity rather than immunity specific to beta cells. The absence of cellular immunity to BSA and ABBOS in IDDM does not support a role for this antigen in the pathogenesis of the disorder.

Islet cell autoantigen 69 kD (ICA69). Molecular cloning and characterization of a novel diabetes-associated autoantigen

We have identified a novel 69-kD peptide autoantigen (ICA69) associated with insulin-dependent diabetes mellitus (IDDM) by screening a human islet lambda gt11 cDNA expression library with cytoplasmic islet cell antibody positive sera from relatives of IDDM patients who progressed to the overt disease. The deduced open reading frame of the ICA69 cDNA predicts a 483-amino acid protein. ICA69 shows no nucleotide or amino acid sequence relation to any known sequence in GenBank, except for two short regions of similarity with BSA. The ICA69 cDNA probe hybridizes with a 2-kb mRNA in poly(A+) RNA from human pancreas, brain, heart, thyroid, and kidney, but not with skeletal muscle, placenta, spleen, or ovary. Expression of ICA69 was also detected in beta cells and cell lines, as well as in tumoral tissue of islet cell origin. The native ICA69 molecule migrates to 69 kD in SDS-PAGE as detected with specific antibodies. Serum samples from relatives of IDDM patients specifically reacted with affinity-purified recombinant ICA69 on Western blotting. The structural gene for ICA69 was designated ICA1. A homologue in the mouse, designated Ica-1 was mapped to the proximal end of chromosome 6 (within 6 cM of the Met protooncogene). ICA69 adds a novel autoantigen to the family of identified islet target molecules, and by the manner of its identification and characterization large amounts of antigen are available for development of quantitative, convenient predictive assays for autoantibodies and analysis of the role of this molecule in diabetes autoimmunity, as well as its physiologic function.

Cow's milk, diabetes, and infant feeding

Recently, a link between the serum level of antibody to cow's milk protein and the onset of insulin-dependent diabetes mellitus in humans was reported. This observation renewed controversy regarding the suitability of cow's milk in infant diets.

Intervention therapies for insulin-dependent diabetes

Treatment of insulin-dependent diabetes remains problematic since there continues to be high rates of morbidity and mortality among affected patients. Good outcomes are most likely to be more common among patients who maintain endogenous insulin reserves for the longest time following diagnosis. The disease process can now be identified in its early, pre-symptomatic stages and thus, the time has come for the investigation of preventive therapies through multicenter clinical trials. A wide variety of strategies are available and their choice should be dependent on the pathogenic stage of disease at which treatment is initiated. This stage-specific approach to prevention is discussed with a particular focus on those therapies that will soon be tested in clinical trials.

Disease-associated anti-bovine serum albumin antibodies in type 1 (insulin-dependent) diabetes mellitus are detected by particle concentration fluoroimmunoassay, and not by enzyme linked immunoassay

We recently developed a particle concentration fluoroimmunoassay for the measurement of serum antibodies to bovine serum albumin in patients with Type 1 (insulin-dependent) diabetes mellitus. We observed elevated IgG-anti-bovine serum albumin antibodies in 100% of newly-diagnosed diabetic children and in 2.5% of matched control children. Here we compare the fluoroimmunoassay and the more commonly available enzyme linked immunoassay technique, exchanging coded serum samples from 40 newly-diagnosed diabetic children and 179 control children between two laboratories. Particle concentration fluoroimmunoassay detected elevated IgG-anti-bovine serum albumin antibodies in all diabetic children, enzyme immunoassay in 25% (p less than 0.0001). Fluoroimmunoassay detected elevated levels in 2.2% and enzyme immunoassay in 10% of control children (p less than 0.002). Elevated IgA-anti-bovine serum albumin antibodies in patients were slightly more often detected by fluoroimmunoassay than by enzyme immunoassay, while in control children enzyme immunoassays detected elevated levels three times more often (p less than 0.01). Values measured in either assay showed overall no correlation in either patient (IgG:rs = 0.28; IgA:rs = 0.11) or control sera (IgG:rs = 0.02; IgA:rs = -0.05). Fluoroimmunoassay for IgG was 100% disease-sensitive (enzyme immunoassay: 25%, p less than 0.0001) and more disease-specific (IgG; p less than 0.02). Our findings demonstrate that these assay techniques detected distinct subsets of anti-bovine serum albumin antibodies with little (IgG) or some (IgA) overlap. In fluoroimmunoassay procedures, antigen:antibody binding occurs within 1-2 min while hours are allowed in an enzyme immunoassay.(ABSTRACT TRUNCATED AT 250 WORDS)