Feasibility and compliance in a nutritional primary prevention trial in infants at increased risk for type 1 diabetes.

AIM: The international Trial to Reduce IDDM in the Genetically at Risk (TRIGR) was launched to determine whether weaning to a highly hydrolysed formula in infancy reduces the incidence of type 1 diabetes in children at increased genetic disease susceptibility. We describe here the findings on feasibility and compliance from the pilot study. METHODS: The protocol was tested in 240 children. The diet of the participating children was assessed by self-administered dietary forms, a structured questionnaire and a food record. Blood samples were taken and weight and height measured at birth and at 3, 6, 9, 12, 18 and 24 months. RESULTS: A majority of the subjects (84%) were exposed to the study formula at least for 2 months. Linear growth or weight gain over the first 2 years of life was similar in the two study groups. The levels of IgA and IgG antibodies to cow's milk and casein were higher in the cow's milk-based formula group than in the hydrolysed formula group during the intervention period (p<0.05), reflecting the difference in the intake of cow's milk protein. CONCLUSION: This randomized trial on infant feeding turned out to be feasible, and dietary compliance was acceptable. Valuable experience was gained for the planning and sample size estimation of the study proper.

Dietary manipulation of beta cell autoimmunity in infants at increased risk of type 1 diabetes: a pilot study.

AIMS/HYPOTHESIS: We aimed to assess the feasibility of a dietary intervention trial with weaning to hydrolysed formula in infants at increased risk of type 1 diabetes and to study the effect of the intervention on the emergence of diabetes-associated autoantibodies in early childhood. METHODS: We studied 242 newborn infants who had a first-degree relative with type 1 diabetes and carried risk-associated HLA-DQB1 alleles. After exclusive breastfeeding, the infants underwent a double-blind, randomised pilot trial of either casein hydrolysate (Nutramigen; Mead Johnson) or conventional cow's milk-based formula until the age of 6-8 months. During a mean observation period of 4.7 years, autoantibodies to insulin, anti-glutamic acid decarboxylase and insulinoma-associated antigen-2 were measured by radiobinding assays, and islet cell antibodies (ICA) by immunofluorescence. RESULTS: The feasibility of screening and identifying a cohort of first-degree relatives with HLA-conferred disease susceptibility, enrolling them in a dietary intervention trial and following them for seroconversion to autoantibody positivity is established. The cumulative incidence of autoantibodies was somewhat smaller in the casein hydrolysate vs control formula group, suggesting the need for a larger well-powered study. After adjustment for duration of study formula feeding, life-table analysis showed a significant protection by the intervention from positivity for ICA (p=0.02) and at least one autoantibody (p=0.03). CONCLUSIONS/INTERPRETATION: The present study provides the first evidence ever in man, despite its limited power, that it may be possible to manipulate spontaneous beta cell autoimmunity by dietary intervention in infancy.

Differential immune response to B:9-23 insulin 1 and insulin 2 peptides in animal models of type 1 diabetes.

Mice have two insulin genes that differ in the insulin sequence by two amino acids, including the B9 position. Given prior studies of the B:9-23 insulin peptide in NOD mice, a fundamental question is whether the immune response to the B:9-23 peptide of the two insulins is identical. We investigate responses to the immunization with B:9-23 insulin 1 and 2 peptides in NOD and RIP-B7.1 Balb/c mice. NOD and F1 (Balb/c x C57/Bl6) B7.1 transgenic mice were given either B:9-23 insulin 1, B:9-23 insulin 2 or tetanus toxoid (TT) control peptide. Insulin autoantibodies (IAA), and anti-B:9-23 antibodies (IgG1 and IgG2c) were measured. Subcutaneous injection of the insulin 2 but not the insulin 1 peptide significantly protected NOD mice from diabetes. Conceptually similar, insulin 1 peptide immunization accelerated diabetes in the B7.1 mice compared with insulin 2 peptide. Insulin 1 and 2 peptides induced similar levels of IAA in the NOD mice except at week 26, where insulin 2 induced higher levels of IAA. Anti-IgG1 B:9-23 peptide antibodies were higher in the insulin 2 immunized group of NOD mice, while IgG2c anti-B:9-23 peptide antibodies were higher in the insulin 1 group. Adoptive transfer of splenocytes from insulin 1 immunized mice to NOD.scid mice demonstrated accelerated diabetogenicity. The protection afforded by insulin 2 peptide but not insulin 1 peptide in the NOD mouse is reflected by its predominant Th2 humoral response. This may relate to the protection conferred by the insulin 1 knockout when bred onto NOD mice in contrast to acceleration of disease with an insulin 2 knockout.

Humoral beta-cell autoimmunity is rare in patients with the congenital rubella syndrome.

The congenital rubella syndrome (CRS) is associated with increased risk for diabetes and thyroid disease. However, the mechanisms by which the rubella virus may cause these diseases are poorly characterized. Previous studies were carried out before modern immunological methods were available. The present study aimed at evaluating whether autoimmune mechanisms are involved in the pathogenesis by analysing antibodies to biochemically characterized autoantigens. The incidence of clinical diabetes, thyroid disease, coeliac disease and related antibodies (islet cell antibodies, ICA; insulin autoantibodies, IAA; antibodies to the tyrosine phosphatase related IA-2 molecule, IA-2 A and glutamic acid decarboxylase, GADA; thyroid peroxidase, TPO; tissue transglutaminase, TTGA; and gliadin, AGA) and HLA risk genotypes were analysed in 37 subjects affected by or exposed to rubella during fetal life (mean age 22.5 years). One patient had diabetes and four patients had clinical hypothyroidism at the time of the examination. ICA, IAA, GADA or IA-2 A were not detected in any of the patients, while five patients tested positive for TPO antibodies. Coeliac disease or TTGA were not observed. Eight patients carried the HLA-DR3-associated HLA-DQB1*02-DQA1*05 haplotype. These results provide no evidence of an increased frequency of markers for humoral beta-cell autoimmunity in patients with CRS suggesting that diabetes in CRS may be caused by other than autoimmune mechanisms.

Effect of cow's milk exposure and maternal type 1 diabetes on cellular and humoral immunization to dietary insulin in infants at genetic risk for type 1 diabetes. Finnish Trial to Reduce IDDM in the Genetically at Risk Study Group.

Type 1 diabetes is considered to be a T-cell-mediated autoimmune disease in which insulin-producing beta-cells are destroyed. Immunity to insulin has been suggested to be one of the primary autoimmune mechanisms leading to islet cell destruction. We have previously shown that the first immunization to insulin occurs by exposure to bovine insulin (BI) in cow's milk (CM) formula. In this study, we analyzed the development of insulin-specific T-cell responses by proliferation test, emergence of insulin-binding antibodies by enzyme immunoassay, and insulin autoantibodies by radioimmunoassay in relation to CM exposure and family history of type 1 diabetes in infants with a first-degree relative with type 1 diabetes and increased genetic risk for the disease. The infants were randomized to receive either an adapted CM-based formula or a hydrolyzed casein (HC)-based formula after breast-feeding for the first 6-8 months of life. At the age of 3 months, both cellular and humoral responses to BI were higher in infants exposed to CM formula than in infants fully breast-fed (P = 0.015 and P = 0.007). IgG antibodies to BI were higher in infants who received CM formula than in infants who received HC formula at 3 months of age (P = 0.01), but no difference in T-cell responses was seen between the groups. T-cell responses to BI at 9 months of age (P = 0.05) and to human insulin at 12 (P = 0.014) and 24 months of age (P = 0.009) as well as IgG antibodies to BI at 24 months of age (P = 0.05) were lower in children with a diabetic mother than in children with a diabetic father or a sibling, suggesting possible tolerization to insulin by maternal insulin therapy. The priming of insulin-specific humoral and T-cell immunity occurs in early infancy by dietary insulin, and this phenomenon is influenced by maternal type 1 diabetes.

Effect of maternal diet during lactation on development of bovine insulin-binding antibodies in children at risk for allergy.

BACKGROUND: The role of exposure to dietary antigens through maternal milk is intriguing, because it may result either in immunization or in tolerance. Exposure to cow's milk proteins results in antibody formation against bovine insulin in infants at risk for type 1 diabetes. OBJECTIVE: To study the appearance of IgG antibodies to bovine and human insulin in infants with an atopic family history whose mothers followed a cow's milk-free diet during the first 3 months of lactation. METHODS: In a prospective cohort study on prevention of food allergies, 123 infants were exclusively breast-fed or received supplementation with a hydrolyzed casein-based formula (Nutramigen) until the age of 6 months. The mothers either avoided cow's milk during the first 3 months of lactation (diet group) or had an unrestricted diet (nondiet group). The levels of IgG antibodies to bovine and human insulin were determined by enzyme immunoassay at 3, 6, 12, and 18 months and at 4 years. In addition, cord blood was obtained at birth and a maternal sample at delivery. RESULTS: At 3 months, IgG antibodies to bovine insulin were low in both dietary groups (median levels 0.150 and 0. 114 optical density units in the diet and nondiet groups). After exposure to dietary insulin, IgG antibodies to bovine insulin increased in both groups, reaching a peak at 12 months in the nondiet group and at 18 months in the diet group. At 18 months, IgG antibodies to bovine insulin were lower in infants in the nondiet group than in infants in the diet group (0.287 vs 0.500, P<.0001). At 4 years, the antibodies no longer differed between the groups. CONCLUSION: The exposure to cow's milk proteins through breast milk during the first 3 months of life resulted in decreased levels of antibodies to dietary bovine insulin at 18 months of age, suggesting a role for breast milk antigens in early tolerance induction.

Relation of inflammation to vascular function in patients with coronary heart disease.

Endothelium plays a pivotal role in the regulation of vascular relaxation. Inflammation may in turn induce endothelial dysfunction and thus increase the risk of atherothrombosis. We investigated 31 men with angiographically verified coronary heart disease, aged 57. 7+/-5.3 years, in regard to endothelium-dependent, acetylcholine-induced, and to endothelium-independent, sodium nitroprusside-induced vasodilatation in the forearm vasculature by strain-gauge plethysmography. Logistic regression analysis served to determine the relation between forearm vascular function and the inflammatory factors measured, concentration of C-reactive protein, subtypes of peripheral blood T-lymphocytes, and other factors potentially affecting endothelial function (lipoprotein and glucose levels). Concentration of C-reactive protein was an independent determinant of endothelium-dependent vascular function (P<0.001 for low dose acetylcholine, P=0.01 for high dose acetylcholine). Other determinants of endothelium-dependent vascular dysfunction were CD8-lymphocytes expressing ICAM-1 (P=0.001), antibodies to oxidized low-density lipoprotein (P<0.001), and body weight (P=0.007). The present data showed an association between inflammatory risk factors linked to atherothrombosis and endothelial dysfunction in coronary heart disease patients. It is possible that endothelial dysfunction in coronary heart disease patients is related to the chronic inflammation or infection coexisting with atherosclerosis.

Cow's milk formula feeding induces primary immunization to insulin in infants at genetic risk for type 1 diabetes.

Insulin autoantibodies (IAAs) often appear as the first sign of islet cell autoimmunity in prediabetic children. Because cow's milk contains bovine insulin, we followed the development of insulin-binding antibodies in children fed with cow's milk formula. Bovine insulin- and human insulin-binding antibodies by enzyme immunoassay and IAA by radioimmunoassay were analyzed in 200 infants carrying HLA-DQB1*0302 but no protective alleles who participated in a Finnish population-based birth-cohort study. Based on the prospectively registered information, the first 100 infants enrolled in the study who were exposed to cow's milk formula before age 12 weeks and the first 100 infants enrolled in the study who were exclusively breast-fed for longer than their first 12 weeks of life were selected for the present study. Also, 11 children from the birth cohort who developed at least two diabetes-associated autoantibodies, 98 children with newly diagnosed type 1 diabetes, and 92 healthy children were studied. We found that the amount of IgG-antibodies binding to bovine insulin was higher at age 3 months in infants who were exposed to cow's milk formula than in infants who were exclusively breast-fed at that age (median 0.521 vs. 0.190; P < 0.0001). The antibodies binding to bovine insulin cross-reacted with human insulin. None of these infants tested positive for IAA. The levels of bovine insulin-binding antibodies declined in both groups at ages 12 and 18 months, whereas in the 11 children with at least two diabetes-associated autoantibodies the levels increased during the follow-up period (P < 0.0001). IgG antibodies correlated with IgG2 antibodies binding to bovine insulin (r = 0.43, P = 0.004) and IAA (r = 0.27, P = 0.02) in diabetic children, but not in healthy children. Cow's milk feeding is an environmental trigger of immunity to insulin in infancy that may explain the epidemiological link between the risk of type 1 diabetes and early exposure to cow's milk formulas. This immune response to insulin may later be diverted into autoaggressive immunity against beta-cells in some individuals, as indicated by our findings in children with diabetes-associated autoantibodies.

Cow milk feeding induces antibodies to insulin in children--a link between cow milk and insulin-dependent diabetes mellitus?

Exposure to cow milk (CM)-based formulas in early infancy has been associated with an increased risk of insulin-dependent diabetes mellitus (IDDM), but studies on the possible pathogenic mechanism(s) linking CM and IDDM are contradicting. We hypothesized that if CM formulas contained bovine insulin (BI), exposure to them could lead to immunization against insulin, which is the only known beta-cell-specific autoantigen in IDDM. We measured immunoglobulin G (IgG) antibodies by enzyme immunoassay (EIA) to BI and human insulin (HI) in children who received, during the first 9 months of life, either a formula containing whole CM proteins or a formula containing hydrolyzed casein (HC) peptides. BI was detectable by radioimmunoassay (RIA) and immunoblotting in the CM-based formula. At 6 months of age the children who received CM formula had higher levels of IgG antibodies to BI than children who received either HC formula or children who were exclusively breast-fed (median levels 0.480 versus 0.185, P = 0.04; and 0.480 versus 0.160, P = 0.04; respectively). Also, at 9 months of age, children in the CM group differed from the HC group (0.403 versus 0.230; P = 0.02). Antibodies to BI and HI showed a positive correlation and cross-reacted in inhibition studies. The high incidence of insulin-binding antibodies in young children with IDDM may be explained by oral immunization to BI present in CM. Exposure to BI, which differs from HI only by three amino acids, may break the tolerance to insulin.

Glutamate decarboxylase-reactive peripheral blood lymphocytes from patients with IDDM express gut-specific homing receptor alpha4beta7-integrin.

Migration of lymphocytes to the pancreas is a prerequisite for insulitis in IDDM. Mucosal vascular addressin (MAdCAM-1), involved in the recirculation of lymphocytes to the gut, has been found in the inflamed islets in NOD mice. In humans, triggers of the gut immune system (e.g., early exposure to cow's milk proteins in infancy, exposure to enteroviral infections) have been associated with IDDM. To study the possible link between the gut immune system and IDDM, we tested the expression of the alpha4beta7-integrin, a homing receptor for MAdCAM-1, on GAD65-reactive lymphocytes. Using immunomagnetic cell sorting, we depleted the lymphocytes with high expression of alpha4beta7-integrin in the peripheral blood mononuclear cell population from IDDM patients and patients with autoimmune polyendocrine disease type 1 (APD-I). The depletion led to a marked decrease (mean 70%) in the cellular response against GAD65 in three of six IDDM patients and in one subject at high risk for IDDM. A decrease of 37% in the GAD response was observed after depletion in the case of one APD-I patient who also had IDDM. Cellular response to tetanus toxoid increased in the majority of patients as well as in three control subjects studied. We demonstrated that a remarkable population of islet cell antigen-reactive lymphocytes express the gut-specific homing receptor, which emphasizes the role of gut immunity in IDDM. The manipulation of the gut immune system is therefore proposed as a tool for modulation of the autoimmunity against pancreatic beta-cells in IDDM.

Soluble adhesion molecules and oral antigen feeding in infants.

Oral administration of foreign proteins, e.g. cow's milk (CM) proteins, stimulates the immune system and induces humoral and cellular immune response against these antigens in infants. Up-regulation of adhesion molecules is known to be associated with activation of the immune system. The purpose of the study was to examine whether orally administered CM proteins induce elevation in soluble adhesion molecules, i.e. intercellular adhesion molecule-1 (ICAM-1) and L-selectin, in infants. In a double-blind trial, 10 infants received CM-based formula and 10 infants casein hydrolysate formula until the age of 9 mo. The infants of mothers with insulin-dependent diabetes mellitus (IDDM) were recruited into a pilot study of a trial for primary prevention of IDDM by elimination of CM proteins from the diet during early infancy. A cord blood sample and peripheral blood samples were taken at the ages of 3, 6, 9, and 12 mo of age. The levels of soluble ICAM-1 and L-selectin were measured by ELISA. The levels of soluble ICAM-1 were higher at the ages of 3, 6, 9, and 12 mo in infants who received CM-based formula than in infants who received hydrolyzed formula (p = 0.05). Instead, no difference was found in the the levels of soluble L-selectin. The levels of soluble ICAM-1 and L-selectin were higher in all infants when compared with the levels reported in adults or to the levels seen in cord blood. Orally fed CM proteins induce an elevation in soluble ICAM-1 in infants. This may reflect the generation of an immune response against these proteins, because ICAM-1 has an important costimulatory role in lymphocyte activation.