Neonatal levels of adiponectin, interleukin-10 and interleukin-12 are associated with the risk of developing type 1 diabetes in childhood and adolescence: A nationwide Danish case-control study

BACKGROUND/AIM

An in-depth understanding of the early phase of type 1 diabetes (T1D) pathogenesis is important for targeting primary prevention. We examined if 14 preselected mediators of immune responses differed in neonates that later developed T1D compared to control neonates.

METHODS

The study is a case-control study with a 1:2 matching. The individuals were born between 1981 through 2002. Cases were validated using the National Patient Register and the Danish Childhood Diabetes Register. Interleukin(IL)-1β, IL-4, IL-6, IL-8, IL-10, IL-12p70, interferon gamma, tumor necrosis factor alpha, transforming growth factor beta 1 (active form), leptin, adiponectin, c-reactive protein, mannose-binding lectin and soluble triggering receptor expressed on myeloid cells-1 were measured by using a flowmetric Luminex xMAP® technology. We tested two models both including a number of possible confounders. In the first model (model 1) we also adjusted for HLA-DQB1 genotype. A total of 1930 groups of assay-matched cases and controls (4746 individuals) were included in the statistical analyses.

RESULTS

Adiponectin was negatively associated with later risk of T1D in both models (relative change (RC), model 1: 0.95, P=0.046 and model 2: 0.95, P=0.006). IL-10 and IL-12 were both positively associated with T1D risk in the model 2 (RC, 1.19, P=0.006 and 1.07, P=0.02, respectively)-these results were borderline significant in model 1, but showed the same direction as the results from model 2.

CONCLUSIONS

Our results indicate that specific immunological signatures are already present at time of birth in children developing T1D before the age of 18years.

Levels of adiponectin and leptin at onset of type 1 diabetes have changed over time in children and adolescents

Adiponectin and leptin are proteins secreted by the adipose tissue and have an influence on insulin sensitivity and on inflammatory markers. Altered levels could play a part in the pathogenesis of type 1 diabetes mellitus. We determined adiponectin and leptin levels over a nine-year period in children with type 1 diabetes mellitus (T1D) in relation to the increasing incidence of T1D, and studied the impact of patient status, age, gender and body mass index (BMI). Data were derived from a population-based registry of diabetic children (DanDiabKids) from 1997 to 2005. Children with newly diagnosed T1D (n = 482) were included, and healthy siblings (n = 479) were chosen as a control group. Leptin levels were significantly higher in recent years (in both patients and siblings), whereas for adiponectin, the levels were lower in recent years in the patient group. Leptin levels were lower in children with T1D (RR 0.74, p = 0.003) and in males (RR 0.52, p < 0.001) and increasing with age in both groups. For adiponectin, there was a negative association between level and age in patients. Both adipokines showed a significant correlation with BMI and lower levels in children with blood samples taken within the first 2 days after initiation of insulin treatment. There has been a change in leptin and adiponectin levels in children with or without T1D from 1997 to 2005. This is not explained by changes in BMI and may reflect changes in other factors like diet or physical activity.

Systemic levels of CCL2, CCL3, CCL4 and CXCL8 differ according to age, time period and season among children newly diagnosed with type 1 diabetes and their healthy siblings

The mechanisms by which antigen-specific T cells migrate to the islets of Langerhans in type 1 diabetes (T1D) are largely unknown. Chemokines attract immune cells to sites of inflammation. The aim was to elucidate the role of inflammatory chemokines in T1D at time of diagnosis. From a population-based registry of children diagnosed with T1D from 1997 to 2005, we studied five different inflammatory chemokines (CCL2, CCL3, CCL4, CCL5 and CXCL8). Four hundred and eighty-two cases and 479 sibling frequencies matched on age and sample year distribution were included. Patients showed lower levels of CCL4 compared to siblings, but this result was not significant after correction for multiple testing. CCL2, CCL3, CCL4 and CXCL8 levels were highest in the most recent cohorts (P < 0.01) in both patients and siblings. A significant seasonal variation - for most of the chemokines - was demonstrated with the highest level during the summer period in both patients and siblings. In addition, there was a significant inverse relationship between CCL4 levels and age. When comparing patients and siblings, remarkably few differences were identified, but interestingly chemokine levels varied with age, season and period for the entire study population. Such variations should be taken into account when studying chemokines in paediatric populations.

Differences in MBL levels between juvenile patients newly diagnosed with type 1 diabetes and their healthy siblings

The incidence of type 1 diabetes (T1D) has during the last few decades been increasing in children and juveniles. Multi-factorial courses combining genetic disposition and environmental factors might be in play, and through the years, there has been a mounting interest in the innate immune system's role in the development of T1D. The aim of this study was to determine mannose binding lectin (MBL) levels in newly diagnosed children with T1D (n=481) over a period of 10 years (1997-2005) and to compare these levels with corresponding levels in their healthy siblings (n=479). Furthermore, the aims were to evaluate if MBL-levels in patients and siblings were influenced by season, age autoimmunity and/or changed over time. The study found that MBL levels differed between patients and their healthy siblings when adjusted for age, gender, season and period. More patients than siblings had MBL levels above 0.8 μg/ml, associated with high producing MBL genotypes, and the elevated MBL levels were associated with high levels of four T1D related cytokines (IL-1β, IL-12, IL-18 and TNF-α). MBL levels increased during the study period and siblings had seasonal variance in concentrations with the lowest level during wintertime (Dec-Feb). In conclusion, more patients than siblings had a high MBL level, and high levels of MBL were related to high levels of T1D specific cytokines, supporting a role of the innate immune system and MBL on the risk of developing T1D.

Hypoglycemia, S-ACE and ACE genotypes in a Danish nationwide population of children and adolescents with type 1 diabetes

OBJECTIVE

High S-ACE levels have been shown to predispose to increased risk of hypoglycemia, however; some inconsistency relates to the risk of the ACE genotype. We investigated the association between S-ACE level at diagnosis and ACE genotype to long-term risk of severe hypoglycemia in more than 1000 children and adolescents with type 1 diabetes being part of the Danish Registry of Childhood diabetes over a 10-yr period.

RESEARCH DESIGN AND METHODS

The Registry provided annual registration of clinical data, e.g., HbA1c, blood glucose monitoring, insulin type and dosage and acute diabetic complications (hypoglycemia and DKA). A BioBank coupled to the Registry comprised serum for measuring S-ACE levels and DNA for ACE genotyping.

RESULTS

A total of 1037 individuals were included, aged 9.97 yr (SD 3.84). A total of 622 severe hypoglycemic episodes were observed in 270 individuals. Associations to increased risk of hypoglycemia generated from a negative binominal model were long diabetes duration (p < 0.0001) and high S-ACE level (p = 0.0497) when adjusted for ACE genotype. In the stratified analysis, S-ACE and insulin dosage were associated with hypoglycemia in girls (p = 0.026 and 0.028, respectively). An association of S-ACE level to ACE genotype was identified; however, no difference in the frequency of hypoglycemia, diabetes duration or HbA1c was demonstrated between ACE genotypes.

CONCLUSION

This large nationwide cohort has identified an increased risk for hypoglycemia associated with higher S-ACE level, however only in girls. A strong association was found between ACE genotype and S-ACE levels, but ACE genotype was not related to risk of hypoglycemia.

Danish children born with glutamic acid decarboxylase-65 and islet antigen-2 autoantibodies at birth had an increased risk to develop type 1 diabetes

OBJECTIVE

A large, population-based case-control cohort was used to test the hypothesis that glutamic acid decarboxylase-65 (GAD65) and islet antigen-2 autoantibodies (IA-2A) at birth predict type 1 diabetes.

DESIGN AND METHODS

The design was an individually matched case-control study of all Danish type 1 diabetes patients born between 1981 and 2002 and diagnosed before May 1 2004 (median age at diagnosis was 8.8 years). Dried blood spot samples collected 5 days after birth in the 1981-2002 birth cohorts and stored at -25 °C were identified from 2023 patients and from two matched controls (n = 4042). Birth data and information on parental age and diabetes were obtained from Danish registers. GAD65A and IA-2A were determined in a radiobinding assay. HLA-DQB1 alleles were analyzed by PCR using time-resolved fluorescence.

RESULTS

GAD65A and IA-2A were found in 70/2023 (3.5%) patients compared to 21/4042 (0.5%) controls resulting in a hazard ratio (HR) of 7.49 (P < 0.0001). The HR decreased to 4.55 but remained significant (P < 0.0003) after controlling for parental diabetes and HLA-DQB1 alleles. Conditional logistic regression analysis showed a HR of 2.55 (P < 0.0001) for every tenfold increase in the levels of GAD65A and IA-2A. This HR decreased to 1.93 but remained significant (P < 0.001) after controlling for parental diabetes and HLA-DQB1 alleles.

CONCLUSION

These data suggest that GAD65A and IA-2A positivity at birth are associated with an increased risk of developing type 1 diabetes in Danish children diagnosed between 1981 and 2004.

Posttranslational Protein Modifications in Type 1 Diabetes - Genetic Studies with PCMT1, the Repair Enzyme Protein Isoaspartate Methyltransferase (PIMT) Encoding Gene

BACKGROUND

Posttranslational protein modifications have been implicated in the development of autoimmunity. Protein L-isoaspartate (D-aspartate) O-methyltransferase (PIMT) repairs modified proteins and is encoded by PCMT1, located in a region linked to type 1 diabetes (T1D), namely IDDM5.

AIM

To evaluate the association between genetic variations in the PCMT1 gene and T1D.

METHODS

Firstly, PCMT1 was sequenced in 26 patients with T1D (linked to IDDM5) and 10 control subjects. The variations found in PCMT1 were then tested (alone and interacting with a functional polymorphism in SUMO4 and with HLA) for association with T1D in 253 families (using transmission disequilibrium test). In a third step, the association of the functional variation in PCMT1 (rs4816) with T1D was analyzed in 778 T1D patients and 749 controls (using chi-square test). In vitro promoter activity was assessed by transfecting INS-1E cells with PCMT1 promoter constructs and a reporter gene, with or without cytokine stimulation.

RESULTS

Four polymorphisms in complete linkage disequilibrium were identified in PCMT1 (5' to the gene (rs11155676), exon 5 (rs4816) and exon 8 (rs7818 and rs4552)). In the whole cohort of 253 families, the allele associated with increased PIMT enzyme activity (rs4816, allele A) was less frequently transmitted to the affected than to the non-affected offspring (46% vs. 53%, p = 0.099). This finding was even more evident in the subset of families where the proband had high-risk SUMO4 (p = 0.069) or low-risk HLA (p = 0.086). Surprisingly, in the case-control study with 778 cases and 749 controls, an inverse trend was found (40.36% of patients and 36.98% of controls had the allele, p = 0.055). PCMT1 promoter activity increased with cytokine stimulation, but no differences were detected between the constructs adjacent to rs11155676.

CONCLUSION

PCMT1 was virtually associated with T1D in groups defined by other risk genes (SUMO4 and HLA). A general association in a not further defined sample of T1D patients was not evident. Verification in a larger population is needed.

A non-synonymous variant in SLC30A8 is not associated with type 1 diabetes in the Danish population

Genome-wide association scans in type 2 diabetes (T2D) have identified a risk variant, rs13266634 (Arg325Trp), in SLC30A8 on chromosome 8. SLC30A8 encodes a beta-cell specific zinc-ion transporter and rs13266634 has been shown to affect insulin secretion. Recently, autoantibodies for Slc30A8 with high predictive value were demonstrated in individuals with type 1 diabetes (T1D), making this gene an interesting T1D candidate gene. We genotyped rs13266634 in 3008 cases and controls and 246 families from Denmark. Association to T1D could not be demonstrated.

Treatment of Danish adolescent diabetic patients with CSII - a matched study to MDI

OBJECTIVE

To compare two intensified insulin therapy regimens - continuous subcutaneous insulin infusion (CSII) against multiple daily insulin injection (MDI) - in Danish adolescents examined in a prospective, matched controlled study design.

RESEARCH DESIGN AND METHODS

Thirty type 1 diabetic adolescents at CSII and 26 matched MDI controls were included in this open intention-to-treat study. Actrapid was used in both groups. Before study entry, all participants followed a brush-up course in order to minimize study effect. At each visit, the following parameters were recorded: hemoglobin A1c (HbA1c), insulin dose, weight, number of hypoglycemic and diabetic ketoacidosis (DKA) events, and the time resources used. At entry and exit of the study, diet registration and validated quality-of-life (QoL) questionnaires were filled by the participants.

RESULTS

A non-significant decline in HbA1c was seen in both groups (p = 0.468); HbA1c decreased from 9.5 to 8.9% and from 9.7 to 9.5% in the CSII and MDI group, respectively. The insulin dose and the number of severe hypoglycemic events per patient were lower (non-significant) in the CSII group. Both groups showed increased body mass index - highest in the CSII group - and mild to moderate DKA episodes were only seen among CSII users. No differences could be demonstrated within the QoL or diet registrations.

CONCLUSIONS

CSII treatment is beneficial as an intensified insulin therapy for selected type 1 diabetic patients and both MDI and CSII can be offered by the professional diabetes team to better tailor therapy. In future, there is a strong need to identify the characteristics of responders to CSII treatment in order to increase the efficacy and safety of CSII treatment.

Type 1 diabetes risk analysis on dried blood spot samples from population-based newborns: design and feasibility of an unselected case-control study

Development of type 1 diabetes mellitus (T1D) may be triggered pre- or perinatally by multiple factors. Identifying new predisposing T1D markers or combinations of markers in a large, well-characterised case-control collection may be important for future T1D prevention. The present work describes the design and feasibility of a large and unselected case-control study, which will define and evaluate prediction criteria for T1D at the time of birth. Danish registries (Biological Specimen Bank for Neonatal Screening, and the National Discharge Registry) made it possible to identify and collect dried blood spots (DBS) from newborns who later developed T1D (cases) born 1981-2002. DBS samples from 2086 cases and two matching control subjects per case were analysed for genetic and immune factors that are associated with T1D: (a) candidate genes (HLA, INS and CTLA4), (b) cytokines and inflammatory markers, (c) islet auto-antibodies (GAD65A, IA-2A). The objective of the study was to define reliable prediction tools for T1D using samples available at the time of birth. In a unique approach, the study linked a large unselected and population-based sample resource to well-ascertained clinical databases and advanced technology. It combined genetic, immunological and demographic data to develop prediction algorithms. It also provided a resource for future studies in which new genetic markers can be included as they are identified.

[First 10 years with the Danish Registry of Childhood Diabetes]

The nation-wide Danish Registry of Childhood Diabetes and associated biological bank were established in 1996. All children diagnosed with insulin-dependent diabetes mellitus (IDDM) under the age of 15 years are included. In the period 1996-2004 the incidence of IDDM in childhood and adolescence (0-15 years) has increased by 3.5% per year and was 25.7/100.000 in 2004. The average measured glycosylated haemoglobin (HbA1c) value has decreased over the period and was 8.4% in 2005. A registry of type 1 diabetes with a high degree of completeness is feasible, provides useful information about the quality of patient care and is a valuable resource for research.

[Comparison of registration of data from the Danish Childhood Diabetes Register and The National Discharge Register]

In 1996 The Danish Childhood Diabetes Register (DIA-REG B&U) was established. Data are validated yearly against The National Discharge Register (NDR). In the first seven years, 1509 cases were found either in the DSBD or in the NDR. Four percent did not have diabetes. Two percent had another code than DE10. In 5.2% cases, the first registration dates in NDR were a half year or more after onset of diabetes. In addition, there were 29 cases only found in the DSBD. In conclusion, the sensitivity and specificity is high in the NDR, but there is some misclassification and the first admission dates are not equal to the date of disease onset. Thus, studies of diabetes in childhood should be based on a validated register such as the DIA-REG B&U.

Increased prevalence of Down's syndrome in individuals with type 1 diabetes in Denmark: A nationwide population-based study

AIMS/HYPOTHESIS

In patients with Down's syndrome, dogma has long held that the prevalence of diabetes is increased. The aim of the present study was to determine the actual prevalence of Down's syndrome among type 1 diabetic patients.

SUBJECTS, MATERIALS AND METHODS

The background population included all children born in Denmark between 1981 and 2000. Registry-validated and clinical data on type 1 diabetes and Down's syndrome diagnoses were obtained from the National Disease Register and Danish Cytogenetic Central Register, respectively.

RESULTS

The prevalence of Down's syndrome in the background population was 0.09%, whereas we identified a prevalence of Down's syndrome in type 1 diabetes patients of 0.38% (95% CI 0.17-0.75), corresponding to a 4.2-fold increased prevalence compared with the background population (p = 7.3 x 10(-5)).

CONCLUSIONS/INTERPRETATION

To the best of our knowledge this is the first population-based study addressing the prevalence of Down's syndrome among verified type 1 diabetes patients. A more than fourfold increased prevalence of Down's syndrome among type 1 diabetes patients supports the notion that genes on chromosome 21 may confer risk for type 1 diabetes, probably also in the general population.

CBLB variants in type 1 diabetes and their genetic interaction with CTLA4

Type 1 diabetes (T1D) is a multifactorial disease with genetic and environmental components involved. Recent studies of an animal model of T1D, the Komeda diabetes-prone rat, have demonstrated that the Casitas-B-lineage lymphoma b (cblb) gene is a major susceptibility gene in the development of diabetes and other autoimmune features of this rat. As a result of the inhibitory role of Cbl-b in T cell costimulation, dysregulation of Cbl-b may also contribute to autoimmune diseases in man. Different isoforms of Cbl-b exist; we evaluated expression levels of two known transcript variants. Constitutive expression of both isoforms was demonstrated, as well as an increased expression, after cytokine exposure, of an isoform lacking exon 16, suggesting a possible role of this variant in the pathogenesis of autoimmunity. We screened coding regions of the human CBLB gene for mutations in a panel of individuals affected with several autoimmune diseases. Eight single nucleotide polymorphisms (SNPs) were detected. One SNP in exon 12 of the CBLB gene was significantly demonstrated to be associated to T1D in a large Danish T1D family material of 480 families. Evidence for common genetic factors underlying several autoimmune diseases has come from studies of cytotoxic T lymphocyte antigen 4 (CTLA4), which encodes another negatively regulatory molecule in the immune system. Gene-gene interactions probably play substantial roles in T1D susceptibility. We performed stratification of CBLB exon 12 SNP data, according to an established CTLA4 marker, CT60, and evidence for a genetic interaction between the CTLA4 and CBLB genes, involved in the same biological pathway of T cell receptor signaling, was observed.

Decreasing incidence of severe diabetic microangiopathy in type 1 diabetes

OBJECTIVE

Conflicting evidence of a decline in incidence of microvascular complications in type 1 diabetes during the last decades has been reported. To assess recent trends in the cumulative incidence of diabetic microangiopathy in type 1 diabetes, we analyzed data from long-term prospective observational studies lasting >/=20 years.

RESEARCH DESIGN AND METHODS

A total of 600 Caucasian patients with onset of type 1 diabetes between 1965 and 1984 were followed until death or until the year 2000. Patients were divided into four groups based on the year of diabetes onset: group A, 1965-1969 (n = 113); group B, 1970-1974 (n = 130); group C, 1975-1979 (n = 113); and group D, 1979-1984 (n = 244). Group A, B, and C are prevalence cohorts identified in 1984; group D is an inception cohort.

RESULTS

In patients followed for >/=20 years, the cumulative incidence (95% CI) of diabetic nephropathy after 20 years of diabetes (urinary albumin excretion >300 mg/24 h) was reduced in patients with more recent diabetes onset (groups A-D): 31.1% (22.5-39.7) vs. 28.4% (19.8-37.0) vs. 18.9% (10.9-26.9) vs. 13.7% (6.2-21.2) (P = 0.015). Similarly, the cumulative incidence of proliferative retinopathy was as follows: 31.2% (22.2-39.8) vs. 30.3% (22.2-38.4) vs. 19.3% (11.2-27.4) vs. 12.5% (5.2-19.8) (P < 0.01). In the latter groups, antihypertensive treatment was started earlier, blood pressure and HbA(1c) were lower, and fewer patients smoked.

CONCLUSIONS

Our study demonstrates a decrease in the cumulative incidence of diabetic microangiopathy in type 1 diabetes over the past 35 years. Improved glycemic control, lower blood pressure (in part due to early aggressive antihypertensive treatment), and reduced prevalence of smoking rates were associated with the improved prognosis.