Assessment of Enterovirus Antibodies during Early Childhood Using a Multiplex Immunoassay

Enteroviruses are a group of positive single-stranded viruses that belong to the Picornaviridae family. They regularly infect humans and cause symptoms ranging from the common cold and hand-foot-and-mouth disease to life-threatening conditions, such as dilated cardiomyopathy and poliomyelitis. Enteroviruses have also been associated with chronic immune-mediated diseases, such as type 1 diabetes, celiac disease, and asthma. Studying these disease-pathogen connections is challenging due to the high prevalence of enterovirus infections in the population and the transient appearance of the virus during the acute infection phase, which limit the identification of the causative agent via methods based on the virus genome. Serological assays can detect the antibodies induced by acute and past infections, which is useful when direct virus detection is not possible. We describe in this immuno-epidemiological study how the antibody levels against VP1 proteins from eight different enterovirus types, representing all seven of the human infecting enterovirus species, vary over time. VP1 responses first significantly (P < 0.001) decline until 6 months of age, reflecting maternal antibodies, and they then start to increase as the infections accumulate and the immune system develops. All 58 children in this study were selected from the DiabImmnune cohort for having PCR-confirmed enterovirus infections. Additionally, we show that there is great, although not complete, cross-reactivity of VP1 proteins from different enteroviruses and that the response against 3C-pro could reasonably well reflect the recent Enterovirus infection history (ρ = 0.94, P = 0.017). The serological analysis of enterovirus antibodies in sera from children paves the way for the development of tools for monitoring the Enterovirus epidemics and associated diseases. IMPORTANCE Enteroviruses cause a wide variety of symptoms ranging from a mild rash and the common cold to paralyzing poliomyelitis. While enteroviruses are among the most common human pathogens, there is a need for new, affordable serological assays with which to study pathogen-disease connections in large cohorts, as enteroviruses have been linked to several chronic illnesses, such as type 1 diabetes mellitus and asthma exacerbations. However, proving causality remains an issue. In this study, we describe the use of an easily customizable multiplexed assay that is based on structural and nonstructural enterovirus proteins to study antibody responses in a cohort of 58 children from birth to 3 years of age. We demonstrate how declining maternal antibody levels can obscure the serological detection of enteroviruses before the age of six months and how antibody responses to nonstructural enterovirus proteins could be interesting targets for serodiagnosis.

Enhanced influenza A H1N1 T cell epitope recognition and cross-reactivity to protein-O-mannosyltransferase 1 in Pandemrix-associated narcolepsy type 1

Narcolepsy type 1 (NT1) is a chronic neurological disorder having a strong association with HLA-DQB1*0602, thereby suggesting an immunological origin. Increased risk of NT1 has been reported among children or adolescents vaccinated with AS03 adjuvant-supplemented pandemic H1N1 influenza A vaccine, Pandemrix. Here we show that pediatric Pandemrix-associated NT1 patients have enhanced T-cell immunity against the viral epitopes, neuraminidase 175-189 (NA175-189) and nucleoprotein 214-228 (NP214-228), but also respond to a NA175-189-mimic, brain self-epitope, protein-O-mannosyltransferase 1 (POMT1675-689). A pathogenic role of influenza virus-specific T-cells and T-cell cross-reactivity in NT1 are supported by the up-regulation of IFN-γ, perforin 1 and granzyme B, and by the converging selection of T-cell receptor TRAV10/TRAJ17 and TRAV10/TRAJ24 clonotypes, in response to stimulation either with peptide NA175-189 or POMT1675-689. Moreover, anti-POMT1 serum autoantibodies are increased in Pandemrix-vaccinated children or adolescents. These results thus identify POMT1 as a potential autoantigen recognized by T- and B-cells in NT1.

Perturbation of nuclear-cytosolic shuttling of Rx1 compromises extreme resistance and translational arrest of potato virus X transcripts

Many plant intracellular immune receptors mount a hypersensitive response (HR) upon pathogen perception. The concomitant localized cell death is proposed to trap pathogens, such as viruses, inside infected cells, thereby preventing their spread. Notably, extreme resistance (ER) conferred by the potato immune receptor Rx1 to potato virus X (PVX) does not involve the death of infected cells. It is unknown what defines ER and how it differs from HR-based resistance. Interestingly, Rx1 can trigger an HR, but only upon artificial (over)expression of PVX or its avirulence coat protein (CP). Rx1 has a nucleocytoplasmic distribution and both pools are required for HR upon transient expression of a PVX-GFP amplicon. It is unknown whether mislocalized Rx1 variants can induce ER upon natural PVX infection. Here, we generated transgenic Nicotiana benthamiana producing nuclear- or cytosol-restricted Rx1 variants. We found that these variants can still mount an HR. However, nuclear- or cytosol-restricted Rx1 variants can no longer trigger ER or restricts viral infection. Interestingly, unlike the mislocalized Rx1 variants, wild-type Rx1 was found to compromise CP protein accumulation. We show that the lack of CP accumulation does not result from its degradation but is likely to be linked with translational arrest of its mRNA. Together, our findings suggest that translational arrest of viral genes is a major component of ER and, unlike the HR, is required for resistance to PVX.

Unlike Many Disease Resistances, Rx1-Mediated Immunity to Potato Virus X Is Not Compromised at Elevated Temperatures

Specificity in the plant immune system is mediated by Resistance (R) proteins. Most R genes encode intracellular NLR-type immune receptors and these pathogen sensors require helper NLRs to activate immune signaling upon pathogen perception. Resistance conferred by many R genes is temperature sensitive and compromised above 28°C. Many Solanaceae R genes, including the potato NLR Rx1 conferring resistance to Potato Virus X (PVX), have been reported to be temperature labile. Rx1 activity, like many Solanaceae NLRs, depends on helper-NLRs called NRC's. In this study, we investigated Rx1 resistance at elevated temperatures in potato and in Nicotiana benthamiana plants stably expressing Rx1 upon rub-inoculation with GFP-expressing PVX particles. In parallel, we used susceptible plants as a control to assess infectiousness of PVX at a range of different temperatures. Surprisingly, we found that Rx1 confers virus resistance in N. benthamiana up to 32°C, a temperature at which the PVX::GFP lost infectiousness. Furthermore, at 34°C, an Rx1-mediated hypersensitive response could still be triggered in N. benthamiana upon PVX Coat-Protein overexpression. As the Rx1-immune signaling pathway is not temperature compromised, this implies that at least one N. benthamiana helper NRC and its downstream signaling components are temperature tolerant. This finding suggests that the temperature sensitivity for Solanaceous resistances is likely attributable to the sensor NLR and not to its downstream signaling components.

Circulating β cell-specific CD8+ T cells restricted by high-risk HLA class I molecules show antigen experience in children with and at risk of type 1 diabetes

In type 1 diabetes (T1D), autoreactive cytotoxic CD8+ T cells are implicated in the destruction of insulin-producing β cells. The HLA-B*3906 and HLA-A*2402 class I genes confer increased risk and promote early disease onset, suggesting that CD8+ T cells that recognize peptides presented by these class I molecules on pancreatic β cells play a pivotal role in the autoimmune response. We examined the frequency and phenotype of circulating preproinsulin (PPI)-specific and insulin B (InsB)-specific CD8+ T cells in HLA-B*3906+ children newly diagnosed with T1D and in high-risk HLA-A*2402+ children before the appearance of disease-specific autoantibodies and before diagnosis of T1D. Antigen-specific CD8+ T cells were detected using human leucocyte antigen (HLA) class I tetramers and flow cytometry was used to assess memory status. In HLA-B*3906+ children with T1D, we observed an increase in PPI5-12 -specific transitional memory CD8+ T cells compared to non-diabetic, age- and HLA-matched subjects. Furthermore, PPI5-12 -specific CD8+ T cells in HLA-B*3906+ children with T1D showed a significantly more antigen-experienced phenotype compared to polyclonal CD8+ T cells. In longitudinal samples from high-risk HLA-A*2402+ children, the percentage of terminal effector cells within the InsB15-24 -specific CD8+ T cells was increased before diagnosis relative to samples taken before the appearance of autoantibodies. This is the first study, to our knowledge, to report HLA-B*3906-restricted autoreactive CD8+ T cells in T1D. Collectively, our results provide evidence that β cell-reactive CD8+ T cells restricted by disease-associated HLA class I molecules display an antigen-experienced phenotype and acquire enhanced effector function during the period leading to clinical diagnosis, implicating these cells in driving disease.

Activation of immune receptor Rx1 triggers distinct immune responses culminating in cell death after 4 hours

Intracellular nucleotide-binding leucine-rich repeat (NLR)-type immune receptors are a fundamental part of plant immune systems. As infection occurs at foci, activation of immune responses is typically non-uniform and non-synchronized, hampering the systematic dissection of their cellular effects and determining their phasing. We investigated the potato NLR Rx1 using the CESSNA (Controlled Expression of effectors for Synchronized and Systemic NLR Activation) platform. CESSNA-mediated Potato virus X coat protein (CP) expression allowed the monitoring of Rx1-mediated immune responses in a quantitative and reproducible manner. Rx1 was found to trigger a reactive oxygen species (ROS) burst and ion leakage within 1 h and a change in autofluorescence within 2 h after the induction of CP production. After 2 h, HIN1 expression was increased and single-stranded DNA (ssDNA) damage and loss of cellular integrity became apparent, followed by double-stranded DNA (dsDNA) damage after 3 h and increased PR-1a, LOX, ERF1 and AOX1B expression and cell death at 4 h. Nuclear exclusion of Rx1 resulted in increased basal levels of ROS and permitted Rx1 activation by an Rx1-breaking CP variant. In contrast, nuclear-targeted Rx1 showed diminished basal ROS levels, and only avirulent CP could trigger a compromised ROS production. Both nuclear-excluded and nuclear-targeted Rx1 triggered a delayed ion leakage compared with non-modified Rx1, suggesting that ion leakage and ROS production originate from distinct signalling pathways. This work offers novel insights into the influence of Rx1 localization on its activity, and the interplay between Rx1-triggered processes.

Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes

OBJECTIVE

There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.

RESEARCH DESIGN AND METHODS

Subjects from the TrialNet Pathway to Prevention Study (N = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.

RESULTS

At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all P < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all P ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.

CONCLUSIONS

Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.

Low-Dose Anti-Thymocyte Globulin (ATG) Preserves β-Cell Function and Improves HbA1c in New-Onset Type 1 Diabetes

OBJECTIVE

A pilot study suggested that combination therapy with low-dose anti-thymocyte globulin (ATG) and pegylated granulocyte colony-stimulating factor (GCSF) preserves C-peptide in established type 1 diabetes (T1D) (duration 4 months to 2 years). We hypothesized that 1) low-dose ATG/GCSF or 2) low-dose ATG alone would slow the decline of β-cell function in patients with new-onset T1D (duration <100 days).

RESEARCH DESIGN AND METHODS

A three-arm, randomized, double-masked, placebo-controlled trial was performed by the Type 1 Diabetes TrialNet Study Group in 89 subjects: 29 subjects randomized to ATG (2.5 mg/kg intravenously) followed by pegylated GCSF (6 mg subcutaneously every 2 weeks for 6 doses), 29 to ATG alone (2.5 mg/kg), and 31 to placebo. The primary end point was mean area under the curve (AUC) C-peptide during a 2-h mixed-meal tolerance test 1 year after initiation of therapy. Significance was defined as one-sided P value < 0.025.

RESULTS

The 1-year mean AUC C-peptide was significantly higher in subjects treated with ATG (0.646 nmol/L) versus placebo (0.406 nmol/L) (P = 0.0003) but not in those treated with ATG/GCSF (0.528 nmol/L) versus placebo (P = 0.031). HbA_1c was significantly reduced at 1 year in subjects treated with ATG and ATG/GCSF, P = 0.002 and 0.011, respectively.

CONCLUSIONS

Low-dose ATG slowed decline of C-peptide and reduced HbA_1c in new-onset T1D. Addition of GCSF did not enhance C-peptide preservation afforded by low-dose ATG. Future studies should be considered to determine whether low-dose ATG alone or in combination with other agents may prevent or delay the onset of the disease.

A Type 1 Diabetes Genetic Risk Score Predicts Progression of Islet Autoimmunity and Development of Type 1 Diabetes in Individuals at Risk

OBJECTIVE

We tested the ability of a type 1 diabetes (T1D) genetic risk score (GRS) to predict progression of islet autoimmunity and T1D in at-risk individuals.

RESEARCH DESIGN AND METHODS

We studied the 1,244 TrialNet Pathway to Prevention study participants (T1D patients' relatives without diabetes and with one or more positive autoantibodies) who were genotyped with Illumina ImmunoChip (median [range] age at initial autoantibody determination 11.1 years [1.2-51.8], 48% male, 80.5% non-Hispanic white, median follow-up 5.4 years). Of 291 participants with a single positive autoantibody at screening, 157 converted to multiple autoantibody positivity and 55 developed diabetes. Of 953 participants with multiple positive autoantibodies at screening, 419 developed diabetes. We calculated the T1D GRS from 30 T1D-associated single nucleotide polymorphisms. We used multivariable Cox regression models, time-dependent receiver operating characteristic curves, and area under the curve (AUC) measures to evaluate prognostic utility of T1D GRS, age, sex, Diabetes Prevention Trial-Type 1 (DPT-1) Risk Score, positive autoantibody number or type, HLA DR3/DR4-DQ8 status, and race/ethnicity. We used recursive partitioning analyses to identify cut points in continuous variables.

RESULTS

Higher T1D GRS significantly increased the rate of progression to T1D adjusting for DPT-1 Risk Score, age, number of positive autoantibodies, sex, and ethnicity (hazard ratio [HR] 1.29 for a 0.05 increase, 95% CI 1.06-1.6; P = 0.011). Progression to T1D was best predicted by a combined model with GRS, number of positive autoantibodies, DPT-1 Risk Score, and age (7-year time-integrated AUC = 0.79, 5-year AUC = 0.73). Higher GRS was significantly associated with increased progression rate from single to multiple positive autoantibodies after adjusting for age, autoantibody type, ethnicity, and sex (HR 2.27 for GRS >0.295, 95% CI 1.47-3.51; P = 0.0002).

CONCLUSIONS

The T1D GRS independently predicts progression to T1D and improves prediction along T1D stages in autoantibody-positive relatives.

Early childhood infections precede development of beta-cell autoimmunity and type 1 diabetes in children with HLA-conferred disease risk

BACKGROUND

The etiology of type 1 diabetes (T1D) is largely unknown. Infections and microbial exposures are believed to play a role in the pathogenesis and in the development of islet autoimmunity in genetically susceptible individuals.

OBJECTIVE

To assess the relationships between early childhood infections, islet autoimmunity, and progression to T1D in genetically predisposed children.

METHODS

Children with human leukocyte antigen (HLA)-conferred disease susceptibility (N=790; 51.5% males) from Finland (n = 386), Estonia (n = 322), and Russian Karelia (n = 82) were observed from birth up to the age of 3 years. Children attended clinical visits at the age of 3, 6, 12, 18, 24, and 36 months. Serum samples for analyzing T1D-associated autoimmune markers were collected and health data recorded during the visits.

RESULTS

Children developing islet autoimmunity (n = 46, 5.8%) had more infections during the first year of life (3.0 vs 3.0, mean rank 439.1 vs 336.2; P = .001) and their first infection occurred earlier (3.6 vs 5.0 months; P = .005) than children with no islet autoimmunity. By May 2016, 7 children (0.9%) had developed T1D (progressors). Compared with non-diabetic children, T1D progressors were younger at first infection (2.2 vs 4.9 months; P = .004) and had more infections during the first 2 years of life (during each year 6.0 vs 3.0; P = .001 and P = .027, respectively). By 3 years of age, the T1D progressors had twice as many infections as the other children (17.5 vs 9.0; P = .006).

CONCLUSIONS

Early childhood infections may play an important role in the pathogenesis of T1D. Current findings may reflect either differences in microbial exposures or early immunological aberrations making diabetes-prone children more susceptible to infections.

Serum carotenoid and tocopherol concentrations and risk of asthma in childhood: a nested case-control study

BACKGROUND

The antioxidant hypothesis regarding the risk of asthma in childhood has resulted in inconsistent findings. Some data indicate that the role of antioxidants in childhood asthma risk may have a critical time window of effect, but only a well-designed longitudinal cohort study can clarify this hypothesis.

OBJECTIVE

To study the longitudinal associations between serum carotenoid and tocopherol concentrations during the first 4 years of life and asthma risk by the age of 5 years.

METHODS

Based on a case-control design nested within a Finnish birth cohort, 146 asthma cases were matched to 270 controls on birth time, sex, genetic risk, and birth place. Non-fasting blood samples were collected at the ages of 1, 1.5, 2, 3, and 4 years and serum carotenoids and tocopherols were analysed. Parents reported the presence and age at start of persistent doctor-diagnosed asthma in the child at the age of 5 years. Data analyses were conducted using generalized estimating equations.

RESULTS

We did not find strong associations between serum carotenoids and tocopherols and the risk of asthma based on age-specific and longitudinal analyses. Both lower and higher quarters of α-carotene and γ-tocopherol increased the risk of asthma.

CONCLUSIONS

The current findings do not support the suggestion that the increased prevalence of asthma may be a consequence of decreased intake of antioxidant nutrients. Moreover, we did not confirm any critical time window of impact of antioxidants on asthma risk. Replication of these findings in similar longitudinal settings will strengthen this evidence base.

Avoidance of Cow's Milk-Based Formula for At-Risk Infants Does Not Reduce Development of Celiac Disease: A Randomized Controlled Trial

BACKGROUND & AIMS

Feeding during the first months of life might affect risk for celiac disease. Individuals with celiac disease or type 1 diabetes have been reported to have high titers of antibodies against cow's milk proteins. Avoidance of cow's milk-based formula for infants with genetic susceptibility for type 1 diabetes reduced the cumulative incidence of diabetes-associated autoantibodies. We performed a randomized controlled trial in the same population to study whether weaning to an extensively hydrolyzed formula reduced the risk of celiac disease autoimmunity or celiac disease.

METHODS

We performed a double-blind controlled trial of 230 infants with HLA-defined predisposition to type 1 diabetes and at least 1 family member with type 1 diabetes. The infants were randomly assigned to groups fed a casein hydrolysate formula (n = 113) or a conventional formula (control, n = 117) whenever breast milk was not available during the first 6-8 months of life. Serum samples were collected over a median time period of 10 years and analyzed for antibodies to tissue transglutaminase (anti-TG2A) using a radiobinding assay, to endomysium using an immunofluorescence assay, and antibodies to a deamidated gliadine peptide using an immunofluorometry assay. Duodenal biopsies were collected if levels of anti-TG2A exceeded 20 relative units. Cow's milk antibodies were measured during the first 2 years of life.

RESULTS

Of the 189 participants analyzed for anti-TG2A, 25 (13.2%) tested positive. Of the 230 study participants observed, 10 (4.3%) were diagnosed with celiac disease. We did not find any significant differences at the cumulative incidence of anti-TG2A positivity (hazard ratio, 1.14; 95% confidence interval, 0.51-2.54) or celiac disease (hazard ratio, 4.13; 95% confidence interval, 0.81-21.02) between the casein hydrolysate and cow's milk groups. Children who developed celiac disease had increased titers of cow's milk antibodies before the appearance of anti-TG2A or celiac disease.

CONCLUSIONS

In a randomized controlled trial of 230 infants with genetic risk factors for celiac disease, we did not find evidence that weaning to a diet of extensively hydrolyzed formula compared with cow's milk-based formula would decrease the risk for celiac disease later in life. Increased titers of cow's milk antibody before anti-TG2A and celiac disease indicates that subjects with celiac disease might have increased intestinal permeability in early life. ClinicalTrials.gov Number: NCT00570102.

Maternal fatty acid intake during pregnancy and the development of childhood overweight: a birth cohort study

BACKGROUND

Maternal diet during pregnancy may contribute to the risk of offspring adiposity.

OBJECTIVES

The objective of the study is to explore the associations between maternal antenatal dietary fatty acid intake and the risk of offspring overweight and obesity at the ages of 2 to 7 years.

METHODS

In a prospective Finnish birth cohort with 3807 mother-child pairs, maternal diet in late pregnancy was assessed with a food frequency questionnaire. Intakes of total fatty acids and individual saturated, monounsaturated and polyunsaturated fatty acids (PUFAs) were calculated. Generalized estimating equation models were used to study the associations of maternal dietary variables with repeatedly measured offspring overweight and obesity.

RESULTS

In girls, maternal intake ratio of n-6:n-3 PUFAs had a U-shaped association with obesity (adjusted OR for the lowest 2.0 [95% CI 1.27-3.20] and the highest 1.7 [1.03-2.73] vs. the two middle quartiles of n-6:n-3 PUFAs, p = 0.01). In boys, arachidonic acid (20:4n-6): docosahexaenoic acid + eicosapentaenoic acid ratio was associated with obesity (adjusted OR for the lowest 1.0 [0.60-1.57] and the highest 0.5 [0.26-0.88] vs. the two middle quartiles, p = 0.02). Saturated fatty acids and monounsaturated fatty acids were not associated with overweight or obesity in either sex.

CONCLUSIONS

Maternal intakes of PUFAs in late pregnancy were associated with risk of later obesity differently in girls and boys.

A drop in the circulating concentrations of soluble receptor for advanced glycation end products is associated with seroconversion to autoantibody positivity but not with subsequent progression to clinical disease in children en route to type 1 diabetes

BACKGROUND

Advanced glycation end products (AGEs) and their interaction with the receptor for AGEs (RAGE) have been studied for their role in the pathogenesis and complications of type 1 diabetes. Decreased concentrations of soluble RAGE (sRAGE) have been reported in acute autoimmune inflammation. We set out to analyze the changes in sRAGE concentration during preclinical diabetes in children seroconverting to islet autoantibody positivity.

METHODS

We measured serum concentrations of sRAGE in 168 children who progressed to clinical disease and 43 children who turned positive for at least 2 diabetes-associated autoantibodies but remained nondiabetic. We analyzed the sRAGE before seroconversion in the first autoantibody-positive sample and annually thereafter until the diagnosis of type 1 diabetes or end of follow-up.

RESULTS

Both groups had similar sRAGE before seroconversion, but subsequently, sRAGE concentrations were lower (P < .001) in the progressors. The progressors had significantly higher sRAGE concentrations before than after seroconversion (P < .001). The nonprogressors did not experience a similar decrease. The sRAGE concentrations remained stable after seroconversion in both groups.

CONCLUSIONS

These data indicate that sRAGE may be involved in the initiation of beta-cell autoimmunity but not in the progression from beta-cell autoimmunity to clinical disease.

The association of the HLA-A*24:02, B*39:01 and B*39:06 alleles with type 1 diabetes is restricted to specific HLA-DR/DQ haplotypes in Finns

BACKGROUND

We analysed the previously reported association of the HLA-A*24:02, B*18 and B*39 alleles with type 1 diabetes and diabetes associated autoimmunity in the Finnish population applying HLA-DR/DQ stratification.

MATERIALS & METHODS

Haplotype transmission was analysed in 2424 nuclear families from the Finnish Paediatric Diabetes Register. Survival analysis was applied to study the development of islet autoantibodies and further progression to clinical diabetes in the prospective follow-up cohort from the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) Study. The subjects were genotyped for specific HLA class I alleles by sequence-specific hybridization using lanthanide labelled nucleotide probes.

RESULTS

The HLA-B*39:06 allele was found almost exclusively on the (DR8)-DQB1*04 haplotype in which its presence changed the disease risk status of the whole haplotype from neutral to predisposing. The HLA-A*24:02 and the B*39:01 alleles increased the diabetes-associated risk of the DRB1*04:04-DQA1*03-DQB1*03:02 haplotype but the alleles were in linkage disequilibrium and no independent effect could be detected. Within the DIPP cohort, neither the A*24:02 nor the B*39:01 allele were associated with seroconversion but were in contrast associated with increased progression from seroconversion to clinical disease.

DISCUSSION & CONCLUSIONS

The independent predisposing effect of the HLA-B*39:06 allele with type 1 diabetes was confirmed in the Finnish population but the association of the A*24:02 and B*39:01 alleles remained inconclusive whilst both A*24:02 and B*39:01 affected the progression rate from seroconversion to autoantibody positivity to overt type 1 diabetes.

Analyses of regulatory CD4+ CD25+ FOXP3+ T cells and observations from peripheral T cell subpopulation markers during the development of type 1 diabetes in children

Our aim was to study whether the aberrant amount or function of regulatory T cells is related to the development of type 1 diabetes (T1D) in children. We also set out to investigate the balance of different T cell subtype markers during the T1D autoimmune process. Treg cells were quantified with flow cytometric assay, and the suppression capacity was analysed with a carboxyfluorescein succinimidyl ester (CFSE)-based T cell suppression assay in children in various phases of T1D disease process and in healthy autoantibody-negative control children. The mRNA expression of different T cell subpopulation markers was analysed with real-time qPCR method. The proportion and suppression capacity of regulatory T cells were similar in seroconverted children at an early stage of beta cell autoimmunity and also in children with T1D when compared to healthy and autoantibody-negative children. Significant differences were observed in the mRNA expression of different T cell subpopulation markers in prediabetic children with multiple (≥ 2) autoantibodies and in children with newly diagnosed T1D when compared to the control children. In conclusion, there were no quantitative or functional differences in regulatory T cells between the case and control groups in any phase of the autoimmune process. Decreased mRNA expression levels of T cell subtype markers were observed in children with multiple islet autoantibodies and in those with newly diagnosed T1D, probably reflecting an exhaustion of the immune system after the strong immune activation during the autoimmune process or a generally aberrant immune response related to the progression of the disease.

Genetic susceptibility to type 1 diabetes in childhood - estimation of HLA class II associated disease risk and class II effect in various phases of islet autoimmunity

OBJECTIVE

The HLA-DR/DQ region remains the major determinant of susceptibility to type 1 diabetes (T1D) despite the more than 50 risk affecting loci outside human leukocyte antigen (HLA) region that have been identified. We aimed at developing a simple risk estimation based on HLA class II genotyping, which was also tested by analyzing HLA class II effect on the autoantibody seroconversion and further progression to diabetes.

SUBJECTS AND METHODS

A total of 2991 trio families with a diabetic child from the Finnish Pediatric Diabetes Register were genotyped and the risk contributed by each DR-DQ haplotype calculated through transmission analysis. The genotype risk was estimated based on the summary effect of haplotypes. Genotype grouping was further tested in a subcohort of the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) Study

RESULTS

The summary effect of haplotypes was generally seen in genotypes, while the expected synergistic effect of DR3-DQ2 and DR4-DQ8 (DRB1*04:03 excluded) combination was also clear in the T1D risk association analysis. This highest risk DR/DQ genotype was found in 21.6% of patients and 2.0% of controls, odds ratio (OR) = 13.2 (10.1-17.2), whereas the lowest risk genotype contained only 0.8% of patients and 28.0% of controls, OR = 0.02 (0.01-0.03). In the subcohort from the DIPP study the risk grades correlated clearly with seroconversion for islet autoantibodies and T1D development. In contrast, DR/DQ risk groups did not associate with the progression rate from advanced autoimmunity to clinical diabetes.

CONCLUSIONS

Class II HLA genotype groups improve the estimation of T1D risk. Class II effect is limited to the early phase of the disease process characterized by seroconversion for islet autoantibodies.

Characterization of human organ donors testing positive for type 1 diabetes-associated autoantibodies

In this study we aim to describe the characteristics of non-diabetic organ donors with circulating diabetes-associated autoantibodies collected within the Nordic Network for Islet Transplantation. One thousand and thirty organ donors have been screened in Uppsala for antibodies against glutamic acid decarboxylase (GADA) and islet antigen-2 (IA-2A). The 32 non-diabetic donors that tested positive for GADA (3.3% of all non-diabetic donors) were studied in more detail, together with 32 matched controls. Mean age among the autoantibody-positive donors was 52.6 (range 21-74), family history of type 1 diabetes (T1D) was unknown, and no donor was genetically predisposed for T1D regarding the human leucocyte antigen (HLA) locus. Subjects were analysed for islet cell antibodies (ICA), insulin autoantibodies (IAA) and zinc transporter 8 antibodies (ZnT8A), and pancreas morphology and clinical data were examined. Eight non-diabetic donors tested positive for two antibodies and one donor tested positive for four antibodies. No insulitis or other signs of a diabetic process were found in any of the donors. While inflammatory cells were present in all donors, subjects with high GADA titres had significantly higher CD45 cell numbers in exocrine tissue than controls. The extent of fibrosis was more pronounced in autoantibody-positive donors, even in subjects with lower GADA titres. Notably, it is possible that events not related directly to T1D (e.g. subclinical pancreatitis) may induce autoantibodies in some cases.

Maternal intake of fatty acids and their food sources during lactation and the risk of preclinical and clinical type 1 diabetes in the offspring

AIMS

We examined maternal dietary intake of fatty acids and foods which are sources of fatty acids during lactation and whether they are associated with the risk of preclinical and clinical type 1 diabetes in the offspring.

METHODS

The subjects comprised a cohort of 2,939 mother-child pairs from the prospective Type 1 Diabetes Prediction and Prevention Study. Composition of maternal diet during the third month of lactation was assessed by a validated food frequency questionnaire. Among the children with HLA-conferred susceptibility to type 1 diabetes, 172 developed preclinical and 81 clinical diabetes. Average follow-up for preclinical type 1 diabetes was 7.5 years (range 0.2-14.0 years) and for clinical type 1 diabetes 7.7 years (0.2-14.0 years).

RESULTS

Maternal intake of fatty acids during lactation was not associated with the risk of type 1 diabetes in the offspring. After adjusting for putative confounders, maternal total consumption of red meat and meat products during lactation was associated both with increased risk for preclinical [hazard ratio (HR) 1.19, 95 % CI 1.02-1.40, p = 0.038] and clinical type 1 diabetes (HR 1.27, 95 % CI 1.06-1.52, p = 0.025). In particular, consumption of processed meat products showed an association with increased risk for type 1 diabetes (HR 1.23, 95 % CI 1.02-1.48, p = 0.045). Maternal use of vegetable oils was associated with increased risk for preclinical type 1 diabetes (HR 1.21, 95 % CI 1.03-1.41, p = 0.023).

CONCLUSIONS

Maternal consumption of red meat, especially processed meat, during lactation may increase the risk of type 1 diabetes.

Green areas around homes reduce atopic sensitization in children

Background

Western lifestyle is associated with high prevalence of allergy, asthma and other chronic inflammatory disorders. To explain this association, we tested the ‘biodiversity hypothesis’, which posits that reduced contact of children with environmental biodiversity, including environmental microbiota in natural habitats, has adverse consequences on the assembly of human commensal microbiota and its contribution to immune tolerance.

Methods

We analysed four study cohorts from Finland and Estonia (n = 1044) comprising children and adolescents aged 0.5–20 years. The prevalence of atopic sensitization was assessed by measuring serum IgE specific to inhalant allergens. We calculated the proportion of five land-use types – forest, agricultural land, built areas, wetlands and water bodies – in the landscape around the homes using the CORINE2006 classification.

Results

The cover of forest and agricultural land within 2–5 km from the home was inversely and significantly associated with atopic sensitization. This relationship was observed for children 6 years of age and older. Land-use pattern explained 20% of the variation in the relative abundance of Proteobacteria on the skin of healthy individuals, supporting the hypothesis of a strong environmental effect on the commensal microbiota.

Conclusions

The amount of green environment (forest and agricultural land) around homes was inversely associated with the risk of atopic sensitization in children. The results indicate that early-life exposure to green environments is especially important. The environmental effect may be mediated via the effect of environmental microbiota on the commensal microbiota influencing immunotolerance.

No association between vitamin D and β-cell autoimmunity in Finnish and Estonian children

BACKGROUND

Vitamin D has immunomodulatory properties, such as regulation of FOXP3 expression and regulatory T-cell activity. Our aim was to investigate whether plasma 25-hydroxyvitamin D [25(OH)D] concentrations associate with the development of β-cell autoimmunity and the transcriptional activity of FOXP3 or vitamin D3 convertase gene (CYP27B1) in CD4+ memory T cells.

METHODS

We studied 83 Finnish and 32 Estonian children participating in the DIABIMMUNE and DIPP studies. Twenty-nine Finnish and six Estonian children tested positive for at least one diabetes-associated autoantibody. The plasma concentrations of 25(OH)D and 1,25(OH)₂D were analysed with an enzyme immunoassay. Gene expression of FOXP3 and CYP27B1 in the isolated CD4+ memory T cells was studied with reverse transcription quantitative polymerase chain reaction.

RESULTS

Vitamin D status did not differ between subjects positive and negative for β-cell autoantibodies. Finnish children had higher vitamin D status than Estonian children (p < 0.001). FOXP3 expression was higher in Estonian CD4+ memory T-cell samples than in Finnish samples (p < 0.01) even when including in both groups only children with serum 25(OH)D concentrations in the range of 50-80 nmol/L (p < 0.001).

CONCLUSIONS

These findings do not support a crucial role of circulating 25(OH)D as a regulator of β-cell autoimmunity or FOXP3 expression.

Trans-kingdom cross-talk: small RNAs on the move

This review focuses on the mobility of small RNA (sRNA) molecules from the perspective of trans-kingdom gene silencing. Mobility of sRNA molecules within organisms is a well-known phenomenon, facilitating gene silencing between cells and tissues. sRNA signals are also transmitted between organisms of the same species and of different species. Remarkably, in recent years many examples of RNA-signal exchange have been described to occur between organisms of different kingdoms. These examples are predominantly found in interactions between hosts and their pathogens, parasites, and symbionts. However, they may only represent the tip of the iceberg, since the emerging picture suggests that organisms in biological niches commonly exchange RNA-silencing signals. In this case, we need to take this into account fully to understand how a given biological equilibrium is obtained. Despite many observations of trans-kingdom RNA signal transfer, several mechanistic aspects of these signals remain unknown. Such RNA signal transfer is already being exploited for practical purposes, though. Pathogen genes can be silenced by plant-produced sRNAs designed to affect these genes. This is also known as Host-Induced Genes Silencing (HIGS), and it has the potential to become an important disease-control method in the future.

Early postnatal growth in children with HLA-conferred susceptibility to type 1 diabetes

AIMS/HYPOTHESIS

An association between increased length/height and weight gain and risk of type 1 diabetes (T1D) has been reported in children. We set out to investigate the potential contribution of T1D human leukocyte antigen (HLA) risk genotypes to this association in two countries with a contrasting disease incidence.

METHODS

In Estonia and Finland, length and weight were monitored up to the age of 24 months in 688 subjects. According to their HLA genotypes, the children were divided into four groups, those with very high, high or moderate risk for T1D, as well as a neutral/control group. Relative length and weight (SDS) were assessed and compared at 3, 6, 12, 18 and 24 months using World Health Organization (WHO) growth curves.

RESULTS

The mean relative length at the age of 24 months was lower in the group with the very high risk HLA genotype compared to the controls (p < 0.05). The mean relative weight differed between those two groups at the age of 12, 18 and 24 months (p < 0.05). When Estonian and Finnish cohorts were analyzed separately, the relative length showed similar but non-significant trends in both countries, while in Estonia the changes in weight at some time points still remained significant (p < 0.05).

CONCLUSIONS

Children with the highest HLA-conferred risk for T1D gained less weight and length during the first 24 months of life, and this feature was more pronounced in the Estonian children.

DAYSLEEPER: a nuclear and vesicular-localized protein that is expressed in proliferating tissues

BACKGROUND

DAYSLEEPER is a domesticated transposase that is essential for development in Arabidopsis thaliana [Nature, 436:282-284, 2005]. It is derived from a hAT-superfamily transposon and contains many of the features found in the coding sequence of these elements [Nature, 436:282-284, 2005, Genetics, 158:949-957, 2001]. This work sheds light on the expression of this gene and localization of its product in protoplasts and in planta. Using deletion constructs, important domains in the protein were identified.

RESULTS

DAYSLEEPER is predominantly expressed in meristems, developing flowers and siliques. The protein is mainly localized in the nucleus, but can also be seen in discrete foci in the cytoplasm. Using several vesicular markers, we found that these foci belong to vesicular structures of the trans-golgi network, multivesicular bodies (MVB's) and late endosomes. The central region as well as both the N- and the C-terminus are essential to DAYSLEEPER function, since versions of DAYSLEEPER deleted for these regions are not able to complement the daysleeper phenotype. Like hAT-transposases, we show that DAYSLEEPER has a functionally conserved dimerization domain [J Biol Chem, 282:7563-7575, 2007].

CONCLUSIONS

DAYSLEEPER has retained the global structure of hAT transposases and it seems that most of these conserved features are essential to DAYSLEEPER's cellular function. Although structurally similar, DAYSLEEPER seems to have broadened its range of action beyond the nucleus in comparison to transposases.

Autoantibodies against zinc transporter 8 are related to age, metabolic state and HLA DR genotype in children with newly diagnosed type 1 diabetes

BACKGROUND

We set out to define the characteristics of humoral autoimmunity against ZnT8 in children and adolescents with newly diagnosed T1D in relation to age and metabolic status at diagnosis, human leucocyte antigen (HLA) genotype and family history of T1D.

METHODS

A total of 2115 subjects <15 years of age were analysed for antibodies against zinc transporter 8, ICA, GADA, IAA, IA-2A, HLA DR-DQ genotype, blood pH, plasma glucose and β-hydroxybutyrate concentrations. Their family history of T1D was also recorded.

RESULTS

Zinc transporter 8 antibodies (ZnT8A) were detected in 63% of the cases. ZnT8A positivity was associated with older age at diagnosis (mean 8.2 years versus 7.5 years, p < 0.001). Seven subjects (0.3%) had ZnT8A as their single autoantibody. Diabetic ketoacidosis at diagnosis was less common among subjects with ZnT8A than among those without (16% versus 20%, p = 0.012). The prevalence of ZnT8A was decreased in DR3/DR4 heterozygotes when compared with those with other DR combinations (p < 0.001). Subjects with the neutral DR13-DQB1*0604 haplotype tested more frequently positive for ZnT8A than the rest of the population (p < 0.001). A positive family history of T1D showed no association with ZnT8A prevalence or levels.

CONCLUSIONS

Antibodies for ZnT8 is related to age and metabolic status at diagnosis as well as HLA genotype but does not significantly improve the detection rate of β-cell autoimmunity in Finnish children and adolescents affected by T1D.

Associations of polymorphisms in non-HLA loci with autoantibodies at the diagnosis of type 1 diabetes: INS and IKZF4 associate with insulin autoantibodies

OBJECTIVE

More than 50 loci outside the human leukocyte antigen (HLA) region have been confirmed to affect type 1 diabetes (T1D) risk but their effect on β-cell autoimmunity is poorly defined. We analyzed the association of 35 single nucleotide polymorphism (SNP) markers previously associated with T1D with the presence of disease-predictive autoantibodies at the time of T1D diagnosis.

SUBJECTS AND METHODS

The study cohort comprised 1554 children diagnosed with T1D before the age of 15 yr. The associations between various genotypes and positivity for antibodies against islet cells [islet cell antibodies (ICA)], insulin [insulin autoantibodies (IAA)], glutamic acid decarboxylase (GADA), islet antigen 2 (IA2A), and zinc transporter 8 (ZnT8A) were analyzed.

RESULTS

INS gene polymorphism rs689 and IKZF4 polymorphism (rs1701704) were strongly associated with IAA positivity at the time of T1D diagnosis (p = 0.000004 and 0.00044, respectively). The presence of the T1D-risk conferring INS AA genotype was associated with IAA. In contrast, the presence of the susceptible C allele of the IKZF4 marker was inversely associated with IAA. The INS and IKZF4 polymorphisms were not significantly associated with ICA, GADA, IA2A, or ZnT8A positivity.

CONCLUSIONS

Both INS and IKZF4 polymorphisms modified the probability of IAA positivity at time of T1D onset but the inverse association of IKZF4 risk allele with IAA suggests that the IKZF4 polymorphism is involved in a pathway of β-cell autoimmunity alternate to the route characterized by IAA and development of T1D in early childhood. The IKZF4 gene encodes Eos, which is implicated to play an important role in Treg programming where this gene might exert its influence on T1D risk.

Introduction of complementary foods in infancy and atopic sensitization at the age of 5 years: timing and food diversity in a Finnish birth cohort

OBJECTIVE

To study the associations between timing and diversity of introduction of complementary foods during infancy and atopic sensitization in 5-year-old children.

METHODS

In the Finnish DIPP (type 1 diabetes prediction and prevention) birth cohort (n = 3781), data on the timing of infant feeding were collected up to the age of 2 years and serum IgE antibodies toward four food and four inhalant allergens measured at the age of 5 years. Logistic regression was used for the analyses.

RESULTS

Median duration of exclusive and total breastfeeding was 1.4 (interquartile range: 0.2-3.5) and 7.0 (4.0-11.0) months, respectively. When all the foods were studied together and adjusted for confounders, short duration of breastfeeding decreased the risk of sensitization to birch allergen; introduction of oats <5.1 months and barley <5.5 months decreased the risk of sensitization to wheat and egg allergens, and oats additionally associated with milk, timothy grass, and birch allergens. Introduction of rye <7.0 months decreased the risk of sensitization to birch allergen. Introduction of fish <6 months and egg ≤11 months decreased the risk of sensitization to all the specific allergens studied. The introduction of <3 food items at 3 months was associated with sensitization to wheat, timothy grass, and birch allergens; the introduction of 1-2 food items at 4 months and ≤4 food items at 6 months was associated with all endpoints, but house dust mite. These results were particularly evident among high-risk children when the results were stratified by atopic history, indicating the potential for reverse causality.

CONCLUSIONS

The introduction of complementary foods was consecutively done, and with respect to the timing of each food, early introduction of complementary foods may protect against atopic sensitization in childhood, particularly among high-risk children. Less food diversity as already at 3 months of age may increase the risk of atopic sensitization.

The SLEEPER genes: a transposase-derived angiosperm-specific gene family

BACKGROUND

DAYSLEEPER encodes a domesticated transposase from the hAT-superfamily, which is essential for development in Arabidopsis thaliana. Little is known about the presence of DAYSLEEPER orthologs in other species, or how and when it was domesticated. We studied the presence of DAYSLEEPER orthologs in plants and propose a model for the domestication of the ancestral DAYSLEEPER gene in angiosperms.

RESULTS

Using specific BLAST searches in genomic and EST libraries, we found that DAYSLEEPER-like genes (hereafter called SLEEPER genes) are unique to angiosperms. Basal angiosperms as well as grasses (Poaceae) and dicotyledonous plants possess such putative orthologous genes, but SLEEPER-family genes were not found in gymnosperms, mosses and algae. Most species contain more than one SLEEPER gene. All SLEEPERs contain a C2H2 type BED-zinc finger domain and a hATC dimerization domain. We designated 3 motifs, partly overlapping the BED-zinc finger and dimerization domain, which are hallmark features in the SLEEPER family. Although SLEEPER genes are structurally conserved between species, constructs with SLEEPER genes from grapevine and rice did not complement the daysleeper phenotype in Arabidopsis, when expressed under control of the DAYSLEEPER promoter. However these constructs did cause a dominant phenotype when expressed in Arabidopsis. Rice plant lines with an insertion in the RICESLEEPER1 or 2 locus displayed phenotypic abnormalities, indicating that these genes are functional and important for normal development in rice. We suggest a model in which we hypothesize that an ancestral hAT transposase was retrocopied and stably integrated in the genome during early angiosperm evolution. Evidence is also presented for more recent retroposition events of SLEEPER genes, such as an event in the rice genome, which gave rise to the RICESLEEPER1 and 2 genes.

CONCLUSIONS

We propose the ancestral SLEEPER gene was formed after a process of retro-transposition during the evolution of the first angiosperms. It may have acquired an important function early on, as mutation of two SLEEPER genes in rice, like the daysleeper mutant in A. thaliana gave a developmental phenotype indicative of their importance for normal plant development.

Maternal dietary fat and fatty acid intake during lactation and the risk of asthma in the offspring

AIM

To explore the association between maternal dietary fat and fatty acid (FA) intake during lactation, and the risk of asthma in the offspring by the age of 5 years.

METHODS

The subjects comprised 1798 mother-child pairs from the Type 1 Diabetes Prediction and Prevention (DIPP) Nutrition Study. Dietary intake was assessed by a validated 181-item food frequency questionnaire, which covered the third month of lactation. The cumulative incidence of asthma was assessed at the age of 5 years with a questionnaire modified from the International Study of Asthma and Allergies in Childhood (ISAAC). Cox proportional hazards regression was used for statistical analysis.

RESULTS

The maternal use of margarines during lactation was associated with a marginally increased risk of asthma [hazard ratio (HR) for user vs. nonuser 1.96, 95% confidence interval (CI) 1.01-3.82, p = 0.047] after adjusting for putative confounders. The maternal intakes of n-3 polyunsaturated FA (PUFA) and fish during lactation were not associated with the risk of asthma.

CONCLUSION

Maternal use of margarines during lactation was weakly associated with an increased risk of asthma in the offspring at the age of 5 years. Other fats or FAs during lactation were not associated with the risk of asthma. However, the nonadherence to dietary recommendations regarding especially fats of our study population may restrict the generalizability of our results.

Early seroconversion and rapidly increasing autoantibody concentrations predict prepubertal manifestation of type 1 diabetes in children at genetic risk

AIMS/HYPOTHESIS

The aim of the study was to investigate the timing of the appearance of autoantibodies associated with type 1 diabetes between birth and puberty, the natural fate of these autoantibodies and the predictive power of autoantibody concentrations for early progression to clinical diabetes.

METHODS

Children were recruited to the Type 1 Diabetes Prediction and Prevention Project, an ongoing study based on HLA-conferred genetic risk. Autoantibodies against islet cells, insulin, GAD65 and islet antigen 2 were analysed at 3-12 month intervals, starting from birth.

RESULTS

During the follow-up, 1,320 children (18.4% of the cohort of 7,165 children) were autoantibody positive in at least one sample. Altogether, 184 autoantibody-positive children progressed to type 1 diabetes. Seroconversion occurred at an early age in the progressors (median 1.5 years), among whom 118 (64%) and 150 (82%) seroconverted to autoantibody positivity before the age of 2 and 3 years, respectively. The incidence of seroconversion peaked at 1 year of age. Compared with other autoantibody-positive children, the median autoantibody levels were already markedly higher 3 to 6 months after the seroconversion in children who later progressed to diabetes.

CONCLUSIONS/INTERPRETATION

Early initiation of autoimmunity and rapid increases in autoantibody titres strongly predict progression to overt diabetes before puberty, emphasising the importance of early life events in the development of type 1 diabetes.

Descriptive epidemiology of type 1 diabetes--is it still in?

This edition of 'Then and now' discusses the valuable contribution made by Onkamo and colleagues to the field of type 1 diabetes epidemiology in their widely cited paper 'Worldwide increase in incidence of type I diabetes-the analysis of the data on published incidence trends', which was published 13 years ago (Diabetologia 1999;42:1395-1403). At the time, this represented the most extensive analysis of global trends in the epidemiology of type 1 diabetes, and covered/included a considerably larger geographical area than previous studies. The data confirmed that there was a worldwide increase in the incidence of childhood diabetes during the second half of the 20th century. Predictions made by the group for the incidence rates in 2010 pointed to large increases, but in retrospect these turned out to be too conservative, particularly among younger children. Whether the increase in incidence among children aged <15 years has started to level off is unknown. Looking to the future, more data on the epidemiology of type 1 diabetes over the whole lifespan are definitely needed. In addition, descriptive epidemiology needs to be complemented with 'aetiological' epidemiology generating information on the causes of the incidence and prevalence trends.

Prevalence and characteristics of diabetes among Somali children and adolescents living in Helsinki, Finland

OBJECTIVE

We compared the prevalence and characteristics of diabetes between Somali and Finnish children in the City of Helsinki.

SUBJECTS AND METHODS

Ten Somali and 310 non-Somali children <16 yr of age were treated for diabetes in Helsinki at the end of 2007. We analyzed autoantibodies, HLA alleles, and serum 25-hydroxy-vitamin D [S25(OH)D] concentrations.

RESULTS

The prevalence of diabetes was 40/10,000 (95% CI 19-73/10,000) for the Somali children and 37/10,000 (95% CI 33-41/10,000) for the background population. At least one autoantibody was detected in all seven Somali patients sampled within 18 months after the diagnosis. Most Somalis (75%) carried HLA-conferred susceptibility to type 1 diabetes (T1D), DR3-DQ2 being the dominating HLA haplotype. Low S25(OH)D levels (<40 nmol/L) were seen in 83% of the Somali patients and in 60% of their siblings.

CONCLUSIONS

These data show that (i) Somali children have autoimmune diabetes, (ii) the prevalence of T1D is similar among Somali and Finnish children, and (iii) both affected and unaffected Somali children have low concentrations of S25(OH)D.

Interaction of enterovirus infection and cow's milk-based formula nutrition in type 1 diabetes-associated autoimmunity

BACKGROUND

Enteral virus infections and early introduction of cow's milk (CM)-based formula are among the suggested triggers of type 1 diabetes (T1D)-associated autoimmunity, although studies on their role have remained contradictory. Here, we aimed to analyse whether interactions between these factors might clarify the controversies.

MATERIALS

The study population comprised 107 subjects developing positivity for at least two T1D-associated autoantibodies and 446 control subjects from the Finnish diabetes prediction and prevention cohort. Enterovirus, rotavirus, adenovirus, respiratory syncytial virus and bovine insulin-binding antibodies were analysed from prospective serum samples at 3-24 months of age. Data on infant cow's milk exposure were available for 472 subjects: 251 subjects were exposed to cow's milk before 3 months of age and 221 subjects later in infancy.

RESULTS

Signs of an enterovirus infection by 12 months of age were associated with the appearance of autoimmunity among children who were exposed to cow's milk before 3 months of age. Cox regression analysis revealed a combined effect of enterovirus infection and early cow's milk exposure for the development of ICA and any of the biochemically defined autoantibodies (p = 0.001), of IAA (p = 0.002), GADA (p = 0.001) and IA-2A (p = 0.013).

CONCLUSIONS

The effect of enterovirus infection on the appearance of T1D-associated autoimmunity seems to be modified by exposure to cow's milk in early infancy suggesting an interaction between these factors. Moreover, these results provide an explanation for the controversial findings obtained when analysing the effect of any single one of these factors on the appearance of T1D-associated autoimmunity.

Strategies for the prevention of autoimmune type 1 diabetes

European experts on autoimmune Type 1 diabetes met for 2 days in October 2010 in Cambridge, to review the state-of-the-art and to discuss strategies for prevention of Type 1 diabetes (http://www-gene.cimr.cam.ac.uk/todd/sub_pages/T1D_prevention_Cambridge_workshop_20_21Oct2010.pdf). Meeting sessions examined the epidemiology of Type 1 diabetes; possible underlying causes of the continuing and rapid increase in Type 1 diabetes incidence at younger ages; and lessons learned from previous prevention trials. Consensus recommendations from the meeting were: 1. Resources such as national diabetes registries and natural history studies play an essential role in developing and refining assays to be used in screening for risk factors for Type 1 diabetes. 2. It is crucial to dissect out the earliest physiological events after birth, which are controlled by the susceptibility genes now identified in Type 1 diabetes, and the environmental factors that might affect these phenotypes, in order to bring forward a mechanistic approach to designing future prevention trials. 3. Current interventions at later stages of disease, such as in newly diagnosed Type 1 diabetes, have relied mainly on non-antigen-specific mechanisms. For primary prevention-preventing the onset of autoimmunity-interventions must be based on knowledge of the actual disease process such that: participants in a trial would be stratified according the disease-associated molecular phenotypes; the autoantigen(s) and immune responses to them; and the manipulation of the environment, as early as possible in life. Combinations of interventions should be considered as they may allow targeting different components of disease, thus lowering side effects while increasing efficacy.

Early introduction of root vegetables in infancy associated with advanced ß-cell autoimmunity in young children with human leukocyte antigen-conferred susceptibility to Type 1 diabetes

AIMS

Early introduction of supplementary foods has been implicated to play a role in the development of ß-cell autoimmunity. We set out to study the effects of breastfeeding and age at introduction of supplementary foods on the development of ß-cell autoimmunity.

METHODS

A prospective birth cohort of 6069 infants with HLA-DQB-conferred susceptibility to Type 1 diabetes was recruited between 1996 and 2004. Antibodies against islet cells, insulin, glutamate dehydroxylase and islet antigen 2 were measured at 3- to 12-month intervals. The families recorded at home the age at introduction of new foods and, for each visit, completed a structured dietary questionnaire. The endpoint was repeated positivity for islet cell antibodies plus at least one other antibody and/or clinical Type 1 diabetes (n = 265).

RESULTS

Early introduction of root vegetables (by the age of 4 months) was related to increased risk of developing positivity for the endpoint [hazard ratio (95% CI) for the earliest third 1.75 (1.11-2.75) and for the middle third 1.79 (1.22-2.62) compared with the last third (> 4 months), likelihood ratio test P = 0.006], independently of the introduction of other foods and of several putative socio-demographic and perinatal confounding factors. Introducing wheat, rye, oats and/or barley cereals (P = 0.013) and egg (P = 0.031) early was related to an increased risk of the endpoint, but only during the first 3 years of life.

CONCLUSIONS

Early introduction of root vegetables during infancy is independently associated with increased risk of ß-cell autoimmunity among Finnish children with increased genetic susceptibility to Type 1 diabetes.

Receptor for advanced glycation end-products (RAGE) provides a link between genetic susceptibility and environmental factors in type 1 diabetes

AIMS/HYPOTHESIS

This group of studies examines human genetic susceptibility conferred by the receptor for advanced glycation end-products (RAGE) in type 1 diabetes and investigates how this may interact with a western environment.

METHODS

We analysed the AGER gene, using 13 tag SNPs, in 3,624 Finnish individuals from the FinnDiane study, followed by AGER associations with a high risk HLA genotype (DR3)-DQA1*05-DQB1*02/DRB1*0401-DQB1*0302 (n = 546; HLA-DR3/DR4), matched in healthy newborn infants from the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) Study (n = 373) using allelic analysis. We also studied islets and circulating RAGE in NODLt mice.

RESULTS

The rs2070600 and rs17493811 polymorphisms predicted increased risk of type 1 diabetes, whereas the rs9469089 SNP was related to decreased risk, on a high risk HLA background. Children from the DIPP study also showed a decline in circulating soluble RAGE levels, at seroconversion to positivity for type 1 diabetes-associated autoantibodies. Islet RAGE and circulating soluble RAGE levels in prediabetic NODLt mice decreased over time and were prevented by the AGE lowering therapy alagebrium chloride. Alagebrium chloride also decreased the incidence of autoimmune diabetes and restored islet RAGE levels.

CONCLUSIONS/INTERPRETATION

These studies suggest that inherited AGER gene polymorphisms may confer susceptibility to environmental insults. Declining circulating levels of soluble RAGE, before the development of overt diabetes, may also be predictive of clinical disease in children with high to medium risk HLA II backgrounds and this possibility warrants further investigation in a larger cohort.

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.

Maternal food consumption during pregnancy and risk of advanced β-cell autoimmunity in the offspring

BACKGROUND

Evidence for a putative role of maternal diet during pregnancy in the development of β-cell autoimmunity in the child is scarce. The authors study the association of food consumption during pregnancy and the development of β-cell autoimmunity in the offspring.

SUBJECTS AND METHODS

A prospective Finnish birth cohort of 4297 infants with human leukocyte antigen (HLA)-DQB1-conferred susceptibility to type 1 diabetes and their mothers. Blood samples were collected from the children at 3-12 months intervals to measure type 1 diabetes-associated antibodies: antibodies against islet cells (ICA), insulin, glutamate dehydroxylase, and islet antigen 2. The mothers completed a validated food frequency questionnaire. The end-point was repeated positivity for ICA together with at least one of the other three antibodies. Piecewise-exponential survival models were used. The effective sample size was 3723, with 138 end-points. The median follow-up time was 4.4 years.

RESULTS

Maternal consumption of butter, low-fat margarines, berries, and coffee were inversely associated with the development of advanced β-cell autoimmunity in the offspring, adjusted for genetic risk group and familial diabetes. These associations for low-fat margarines (use vs. non-use HR 0.60, 95% CI: 0.38-0.93, p = 0.02), berries (continuous variable HR 0.90, 95% CI: 0.83-0.98, p = 0.02) and coffee (highest quarter vs. lowest HR 0.62, 95% CI: 0.40-0.97, p = 0.04), remained significant when adjusting for potential confounding sociodemographic, perinatal, and other dietary factors.

CONCLUSIONS

In this study assessing total food consumption of the mother during pregnancy, only few among the 27 food groups tested were weakly related to the development of advanced β-cell autoimmunity in Finnish children.

Sensor-augmented pump therapy from the diagnosis of childhood type 1 diabetes: results of the Paediatric Onset Study (ONSET) after 12 months of treatment

AIMS/HYPOTHESIS

The value of managing children with type 1 diabetes using a combination of insulin pump and continuous glucose monitoring starting from diagnosis for improving subsequent glycaemic control and preserving residual beta cell function was determined.

METHODS

A total of 160 children (aged 1-16 years, mean ± SD: 8.7 ± 4.4 years; 47.5% girls) were randomised to receive insulin pump treatment with continuous glucose monitoring or conventional self-monitoring blood glucose measurements. The primary outcome was the level of HbA(1c) after 12 months. Other analyses included fasting C-peptide, glycaemic variability, sensor usage, adverse events, children's health-related quality of life and parent's wellbeing.

RESULTS

HbA(1c) was not significantly different between the two groups, but patients with regular sensor use had lower values (mean 7.1%, 95% CI 6.8-7.4%) compared with the combined group with no or low sensor usage (mean 7.6%, 95% CI 7.3-7.9%; p=0.032). At 12 months, glycaemic variability was lower in the sensor group (mean amplitude of glycaemic excursions 80.2 ± 26.2 vs 92.0 ± 33.7; p=0.037). Higher C-peptide concentrations were seen in sensor-treated 12- to 16-year-old patients (0.25 ± 0.12 nmol/l) compared with those treated with insulin pump alone (0.19 ± 0.07 nmol/l; p=0.033). Severe hypoglycaemia was reported only in the group without sensors (four episodes).

CONCLUSION/INTERPRETATION

Sensor-augmented pump therapy starting from the diagnosis of type 1 diabetes can be associated with less decline in fasting C-peptide particularly in older children, although regular sensor use is a prerequisite for improved glycaemic control.

TRIAL REGISTRATION

ISRCTN.org ISRCTN05450731

FUNDING

Medtronic International Trading Sàrl, Tolochenaz, Switzerland.

DNA methylation and normal chromosome behavior in Neurospora depend on five components of a histone methyltransferase complex, DCDC

Methylation of DNA and of Lysine 9 on histone H3 (H3K9) is associated with gene silencing in many animals, plants, and fungi. In Neurospora crassa, methylation of H3K9 by DIM-5 directs cytosine methylation by recruiting a complex containing Heterochromatin Protein-1 (HP1) and the DIM-2 DNA methyltransferase. We report genetic, proteomic, and biochemical investigations into how DIM-5 is controlled. These studies revealed DCDC, a previously unknown protein complex including DIM-5, DIM-7, DIM-9, CUL4, and DDB1. Components of DCDC are required for H3K9me3, proper chromosome segregation, and DNA methylation. DCDC-defective strains, but not HP1-defective strains, are hypersensitive to MMS, revealing an HP1-independent function of H3K9 methylation. In addition to DDB1, DIM-7, and the WD40 domain protein DIM-9, other presumptive DCAFs (DDB1/CUL4 associated factors) co-purified with CUL4, suggesting that CUL4/DDB1 forms multiple complexes with distinct functions. This conclusion was supported by results of drug sensitivity tests. CUL4, DDB1, and DIM-9 are not required for localization of DIM-5 to incipient heterochromatin domains, indicating that recruitment of DIM-5 to chromatin is not sufficient to direct H3K9me3. DIM-7 is required for DIM-5 localization and mediates interaction of DIM-5 with DDB1/CUL4 through DIM-9. These data support a two-step mechanism for H3K9 methylation in Neurospora.

Maternal intake of vitamin D during pregnancy and risk of advanced beta cell autoimmunity and type 1 diabetes in offspring

AIMS/HYPOTHESIS

We evaluated the intake of vitamin D by pregnant Finnish women and examined associations between maternal intake of vitamin D and the development of advanced beta cell autoimmunity and type 1 diabetes in their offspring.

METHODS

The research was carried out within the Diabetes Prediction and Prevention study (DIPP), which is a population-based birth cohort of infants at genetic risk of type 1 diabetes. Mothers of 3,723 infants born between 1997 and 2002 completed a validated 181-item food frequency questionnaire, which included questions on dietary supplements. The offspring were observed at 3 to 12 month intervals for the appearance of autoantibodies associated with type 1 diabetes and for the development of clinical type 1 diabetes.

RESULTS

Maternal mean daily intake of vitamin D was 5.1 microg from food and 1.3 microg from supplements. The maternal intake of vitamin D, either from food or from supplements, was not associated with the risk of advanced beta cell autoimmunity/type 1 diabetes in offspring (HR [95% CI] for intake of vitamin D from food 1.25 [0.80-1.95], for vitamin D intake from supplements 1.05 [0.95-1.16]), or with the risk of type 1 diabetes alone (HR [95% CI] for intake of vitamin D from food 0.84 [0.41-1.72], for vitamin D intake from supplements 1.09 [0.99-1.20]).

CONCLUSIONS/INTERPRETATION

Maternal intake of vitamin D either from food or supplements during pregnancy is not associated with advanced beta cell autoimmunity/type 1 diabetes or with type 1 diabetes alone in Finnish offspring carrying increased genetic susceptibility to type 1 diabetes.

The interferon-induced helicase IFIH1 Ala946Thr polymorphism is associated with type 1 diabetes in both the high-incidence Finnish and the medium-incidence Hungarian populations

AIMS/HYPOTHESIS

The rs1990760 polymorphism (Ala946Thr) of interferon induced with helicase C domain 1 (IFIH1) has been proposed to associate with type 1 diabetes. In this study, association between IFIH1 Ala946Thr and type 1 diabetes was investigated in two distinct white populations, the Hungarians and Finns.

METHODS

The rs1990760 polymorphism was genotyped in 757/509 Hungarian/Finnish childhood-onset cases, 499/250 Hungarian/Finnish control individuals and in 529/924 Hungarian/Finnish nuclear family trios. Disease association was tested using case-control and family-based approaches. A meta-analysis of data from 9,546 cases and 11,000 controls was also performed.

RESULTS

In the Hungarian dataset, the A allele was significantly more frequent among cases than among controls (OR 1.29, 95% CI 1.10-1.52; p = 0.002). Combined analysis of Hungarian and Finnish datasets revealed a strong disease association (OR 1.235, 95% CI 1.083-1.408; p = 0.002). Furthermore, the A allele was significantly overtransmitted in both family trio datasets (p = 0.017 in Hungarians; p = 0.007 in Finns). The A allele was increased in Hungarian vs Finnish cases (64.9% vs 60.8% in Finns; p = 0.003). The meta-analysis yielded a significant effect for IFIH1 rs1990760 A allele on type 1 diabetes risk (OR 1.176, 95% CI 1.130-1.225; p = 5.3 x 10(-15)) with significant heterogeneity between effect sizes across the studied populations (p = 0.023).

CONCLUSIONS/INTERPRETATION

This study represents the first independent confirmation of the association between type 1 diabetes and the IFIH1 gene in Hungarian and Finnish populations. Summarising the data published so far, a clear association between the Ala946Thr polymorphism and type 1 diabetes was detected, with an apparent difference in the contribution to disease susceptibility in different populations of European ancestry.

Maternal vitamin D intake during pregnancy is inversely associated with asthma and allergic rhinitis in 5-year-old children

BACKGROUND

Vitamin D is known to have a number of immunological effects and it may play a role in preventing allergic diseases. Objectives To study the effect of maternal intake of vitamin D during pregnancy on the emergence of asthma, allergic rhinitis (AR), and atopic eczema by the age of 5 years in children with HLA-DQB1-conferred susceptibility for type 1 diabetes.

METHODS

Children (1669) participating in the population-based birth cohort study were followed for asthma, AR, and atopic eczema assessed by validated questionnaire at 5 years. Maternal diet was assessed by a food-frequency questionnaire.

RESULTS

The mean maternal intake of vitamin D was 5.1 (SD 2.6) microg from food and 1.4 (2.6) microg from supplements. Only 32% of the women were taking vitamin D supplements. When adjusted for potential confounders, maternal intake of vitamin D from food was negatively related to risk of asthma [hazard ratio (HR) 0.80; 95% confidence interval (CI) 0.64-0.99] and AR [HR 0.85; 95% CI 0.75-0.97]. Vitamin D supplements alone were not associated with any outcome. Adjustment for maternal intake of other dietary factors did not change the results.

CONCLUSION

Maternal vitamin D intake from foods during pregnancy may be negatively associated with risk of asthma and AR in childhood.

Evidence for linkage to and association with type 1 diabetes at the 3q21 region in the Finnish population

IDDM9-region on chromosome 3q has shown suggestive evidence for linkage to type 1 diabetes in some but not all genome scans. We analyzed 22 microsatellite markers in 121 Finnish type 1 diabetes multiplex families across the IDDM9-region. Two-point maximum LOD scores of 3.4 and 2.5 were detected with markers D3S1589 and D3S3606, respectively. Two markers were further tested for association using the transmission disequilibrium test in 384 Finnish type 1 diabetes simplex families. Marker AFM203wd10 showed association with type 1 diabetes (P = 0.0002 for allele R16). Association was present in families with children carrying the HphI-23 AA risk genotype at IDDM2 but not in families with children carrying protective AT or TT genotypes implying interaction between the two loci. Our data gives credence to earlier findings of linkage in this region and suggests a location for a polymorphism affecting type 1 diabetes susceptibility in the area surrounding AFM203wd10.