Maternal exposure to air pollution and type 1 diabetes--Accounting for genetic factors.

BACKGROUND: Genetic and non-genetic factors probably act together to initiate and accelerate development of type 1 diabetes [T1D]. One suggested risk factor contributing to development of T1D is air pollution. OBJECTIVE: The aim of the study was to investigate whether maternal exposure during pregnancy to air pollution, measured as nitrogen oxides [NOx] and ozone, in a low-dose exposure area was associated with the child developing T1D. METHOD: In Scania (Skåne), the most southern county in Sweden, 84,039 infants were born during the period 1999-2005. By the end of April 2013, 324 of those children had been diagnosed with T1D. For each of those T1D children three control children were randomly selected and matched for HLA genotype and birth year. Individually modelled exposure data at residence during pregnancy were assessed for nitrogen oxides [NOx], traffic density and ozone. RESULTS: Ozone as well as NOx exposures were associated with T1D. When the highest exposure group was compared to the lowest group an odds ratios of 1.62 (95% confidence interval [CI] 0.99-2.65) was observed for ozone in the second trimester and 1.58 (95% CI 1.06-2.35) for NOx in the third trimester. CONCLUSION: This study indicates that living in an area with elevated levels of air pollution during pregnancy may be a risk factor for offspring T1D.

Islet cell antibodies (ICA) identify autoimmunity in children with new onset diabetes mellitus negative for other islet cell antibodies.

AIMS: The aim of this study was to explore whether islet cell antibodies (ICA) could be identified in children with newly onset diabetes mellitus but negative for autoantibodies against glutamic acid decarboxylase (GADA), islet antigen-2 (IA-2A), insulin (IAA), or any of the three variants with arginine (R), tryptophan (W), or glutamine (Q) at position 325 of the zinc transporter 8 (ZnT8A). METHODS: A population-based analysis of autoantibodies was performed from 1 May 2005 to 2 September 2010 in Swedish children newly diagnosed with diabetes. ICA was analyzed with an enzyme-linked immunosorbent assay and if positive, reanalyzed in the classical ICA immunofluorescence assay, in 341 samples among 3545 children who had been tested negative for all of GADA, IA-2A, IAA, or ZnT8A (R, W, Q). RESULTS: An isolated positivity for ICA was identified in 5.0% (17/341) of the newly diagnosed children. The levels of ICA in positive subjects ranged from 3 to 183 JDF-U (median 30). This finding increased the diagnostic sensitivity of islet autoimmunity as 3204/3545 patients (90.4%) were islet autoantibody positive without the ICA analyses and 3221 patients (90.9%) were positive with the inclusion of ICA. CONCLUSIONS: The finding of an isolated positivity for ICA despite negativity for GADA, IA-2A, IAA, and ZnT8A (R, W, Q) suggests that still another yet unidentified autoantigen(s) may contribute to the ICA immunofluorescence. Hence, ICA is important to analyze in type 1 diabetes children and adolescents that would otherwise be islet autoantibody negative.

Long-term outcomes of congenital cytomegalovirus infection in Sweden and the United Kingdom.

BACKGROUND: Congenital cytomegalovirus (CMV) is an important cause of neurological problems, particularly sensorineural hearing loss, but data on long-term sequelae and the impact of nonprimary maternal infection are limited. We report updated findings on childhood outcomes from 2 large prospective studies. METHODS: Pregnant women in Malmö, Sweden, and London, United Kingdom, were included between 1977 and 1986, and newborns were screened for CMV (virus culture of urine or saliva). Cases and matched controls underwent regular, detailed developmental assessments up to at least age 5 years. RESULTS: One hundred seventy-six congenitally infected infants were identified among >50 000 screened (Malmö: 76 [4.6/1000 births]; London: 100 [3.2/1000 births]); 214 controls were selected. Symptoms were recorded in 11% of CMV-infected neonates (19/176) and were mostly mild; only 1 neonate had neurological symptoms. At follow-up, 7% of infants (11/154) were classified as having mild, 5% (7/154) moderate, and 6% (9/154) severe neurological sequelae. Four of 161 controls (2%) had mild impairment. Among children symptomatic at birth, 42% (8/19) had sequelae, versus 14% (19/135) of the asymptomatic infants (P = .006). All moderate/severe outcomes were identified by age 1; mild sequelae were first identified at age 2-5 years in 6 children, and age 6-7 years in 3. Among the 16 children with moderate/severe outcomes, 2 had mothers with confirmed and 7 with presumed nonprimary infection. CONCLUSIONS: Moderate or severe outcomes were reported in 11% of children with congenital CMV identified through population screening, all by 1 year; all impairment detected after this age was mild. Nonprimary infections contributed substantially to the burden of childhood congenital CMV disease.

Glucose tolerance and beta-cell function in islet autoantibody-positive children recruited to a secondary prevention study.

AIMS: Children with type 1 diabetes (T1D) risk and islet autoantibodies are recruited to a secondary prevention study. The aims were to determine metabolic control in relation to human leukocyte antigen (HLA) genetic risk and islet autoantibodies in prepubertal children. METHODS: In 47 healthy children with GADA and at least one additional islet autoantibody, intravenous glucose tolerance test (IvGTT) and oral glucose tolerance test (OGTT) were performed 8-65 d apart. Hemoglobin A1c, plasma glucose as well as serum insulin and C-peptide were determined at fasting and during IvGTT and OGTT. RESULTS: All children aged median 5.1 (4.0-9.2) yr had autoantibodies to two to six of the beta-cell antigens GAD65, insulin, IA-2, and the three amino acid position 325 variants of the ZnT8 transporter. In total, 20/47 children showed impaired glucose metabolism. Decreased (≤ 30 µU/mL insulin) first-phase insulin response (FPIR) was found in 14/20 children while 11/20 had impaired glucose tolerance in the OGTT. Five children had both impaired glucose tolerance and FPIR ≤ 30 µU/mL insulin. Number and levels of autoantibodies were not associated with glucose metabolism, except for an increased frequency (p = 0.03) and level (p = 0.01) of ZnT8QA in children with impaired glucose metabolism. Among the children with impaired glucose metabolism, 13/20 had HLA-DQ2/8, compared to 9/27 of the children with normal glucose metabolism (p = 0.03). CONCLUSION: Secondary prevention studies in children with islet autoantibodies are complicated by variability in baseline glucose metabolism. Evaluation of metabolic control with both IvGTT and OGTT is critical and should be taken into account before randomization. All currently available autoantibody tests should be analyzed, including ZnT8QA.

Evaluation of the RSR 3 screen ICA™ and 2 screen ICA™ as screening assays for type 1 diabetes in Sweden.

AIM: The study aim was to evaluate the RSR 3 Screen ICA™ and 2 Screen ICA™ for detection of islet cell autoimmunity in healthy Swedish subjects and patients with newly diagnosed type 1 diabetes (T1D). METHODS: 3 Screen is designed for combined detection of autoantibodies to glutamic acid decarboxylase (GADA), to the islet antigen IA-2 (IA-2A) and to zinc transporter 8 (ZnT8A), while 2 Screen detects GADA and IA-2A. Serum samples from 100 T1D patients at onset and 200 healthy controls were studied. RESULTS: 3 Screen achieved 93% assay sensitivity and 97.5% specificity, while 2 Screen achieved 91% assay sensitivity and 98.5% specificity. Samples were also tested in assays for individual autoantibodies. There was only one 3 Screen positive healthy control sample (0.5%) that was positive for multiple autoantibodies (IA-2A and ZnT8A). In contrast, most of the 93 3 Screen positive patients were positive for multiple autoantibodies with 72% (67/93) positive for both GADA and IA-2A and 57% (53/93) positive for three autoantibodies (GADA, IA-2A and ZnT8A). Insulin autoantibodies (IAA, measured by radioimmunoassay) were positive in 13 patients and two healthy controls. CONCLUSION: 3 Screen achieved high sensitivity and specificity, suitable for islet cell autoimmunity screening in a healthy population. In the case of 3 Screen positivity, further assays for GADA, IA-2A and ZnT8A are required to check for multiple autoantibody positivity, a hallmark for progression to T1D. In addition, testing for IAA in children below two years of age is warranted.

A comparison of serum and EDTA plasma in the measurement of glutamic acid decarboxylase autoantibodies (GADA) and autoantibodies to islet antigen-2 (IA-2A) using the RSR radioimmunoassay (RIA) and enzyme linked immunosorbent assay (ELISA) kits.

BACKGROUND: Glutamic acid decarboxylase antibodies (GADA) and tyrosine phosphatase antibodies (islet antigen-2 antibodies; IA-2A) are used in clinical practise to identify type 1 diabetes. METHODS: GADA and IA-2A were measured with RSR-ELISA kits in samples from 76 newly diagnosed type 1 diabetic children and 120 healthy controls. The aim was to evaluate performance of RSR-ELISA kits for GADA and IA-2A when serum and Ca2+ treated plasma were used. RESULTS: GADA achieved high area under the curve (AUC) both for serum 0.95 (95% CI 0.90-0.99) and for Ca2+ treated plasma 0.95 (95% CI 0.91-0.99). At specificity 98%, sensitivity was 84% for serum and 87% for Ca2+ treated plasma. IA-2A achieved AUC 0.92 (95% CI 0.87-0.97) for serum and 0.94 (95% CI 0.90-0.98) for Ca2+ treated plasma. Using the lowest standard (15 WHO-Units/ml) as cut-off, specificity for serum was 100% and for Ca2+ treated plasma 99% with sensitivity 74% in both cases. Sensitivity was higher in ELISA compared to RIA (74%; p = 0.0080) for GADA measurement and similar for ELISA and RIA IA-2A measurements (76%; p = 0.50). CONCLUSION: Both RSR-ELISAs, GADA and IA-2A showed excellent performance for serum as well as for Ca2+ treated plasma.

Thyroid and Islet Autoantibodies Predict Autoimmune Thyroid Disease at Type 1 Diabetes Diagnosis.

Context: Screening of autoimmune thyroid disease in children with type 1 diabetes is important but varies between clinics. Objective: To determine the predictive value of thyroid autoantibodies, thyroid function, islet autoantibodies, and HLA-DQ at diagnosis of type 1 diabetes for autoimmune thyroid disease during follow-up. Setting: Forty-three Swedish pediatric endocrinology units. Design, Patients, and Main Outcome Measures: At diagnosis of type 1 diabetes, autoantibodies against thyroid peroxidase (TPOAb), thyroglobulin (TGAb), glutamic acid decarboxylase (GADA), insulin, insulinoma-associated protein-2, and 3 variants of zinc transporter 8 (ZnT8W/R/QA) HLA-DQA1-B1 genotypes and thyroid function were analyzed in 2433 children. After 5.1 to 9.5 years, information on thyroxine treatment was gathered from the Swedish National Board of Health and Welfare's Prescribed Drug Register. Results: Thyroxine was prescribed to 6% of patients. In patients <5 years of age, female sex [hazard ratio (HR) = 4.60; P = 0.008] and GADA (HR = 5.80; P = 0.02) were predictors. In patients 5 to 10 years old, TPOAb (HR = 20.56; P < 0.0001), TGAb (HR = 3.40; P = 0.006), and thyroid-stimulating hormone (TSH) (HR = 3.64; P < 0.001) were predictors, whereas in 10 to 15 year olds, TPOAb (HR = 17.00; P < 0.001) and TSH (HR = 4.11; P < 0.001) predicted thyroxine prescription. Conclusion: In addition to TPOAb and TSH, GADA at diagnosis of type 1 diabetes is important for the prediction of autoimmune thyroid disease in children <5 years of age.

Thyroid autoantibodies in cord blood sera from children and adolescents with autoimmune thyroiditis.

Autoimmune thyroid disease is common among women of childbearing age. Thyroid autoantibodies are predominantly of the immunoglobulin G (IgG)-type and pass the placental barrier from mother to child. Recent studies have suggested a pathogenetic role for transplacentally transmitted autoantibodies in the development of autoimmune disease. The aim of the present study was to investigate if children and adolescents with autoimmune thyroiditis (AIT) have been exposed to thyroid autoantibodies already in utero. Cord blood sera taken at delivery from 34 newborns who had developed AIT during childhood and adolescence, and sera from 31 of their mothers, were analyzed for the presence of autoantibodies against thyroid peroxidase (TPOAb) and thyroglobulin (TgAb), and compared to 233 randomly selected control children and their mothers. The prevalence of TPOAb in cord blood sera was elevated among the children and adolescents with AIT compared to controls (38% versus 14%; odds ratio [OR] 4.12, p < 0.001). An increased prevalence of TPOAb was also found among their mothers (29% versus 15%; OR 2.17, p < 0.048). No significant difference in the prevalence of TgAb was found either between children with AIT and the control children (18% versus 9%; OR 2.16, p < 0.15), or between their mothers and the control mothers (23% versus 12%; OR 2.17, p < 0.16). Most of the TPOAb-positive children had TPOAb-positive mothers, indicating the maternal origin of their TPOAb. In conclusion, a large proportion of children who later developed AIT had already been exposed to transplacentally transmitted TPOAb in utero. Whether these autoantibodies have any pathogenetic role in the development of AIT in offspring or if they simply mirror the inheritance of AIT, remains to be investigated.

Relationship between Ljungan virus antibodies, HLA-DQ8, and insulin autoantibodies in newly diagnosed type 1 diabetes children.

Environmental factors, including viral infections, may explain an increasing and fluctuating incidence of childhood type 1 diabetes (T1D). Ljungan virus (LV) isolated from bank voles have been implicated, but it is unclear whether LV contributes to islet autoimmunity, progression to clinical onset, or both, of T1D. The aim was to test whether LV antibodies (LVAb) were related to HLA-DQ and islet autoantibodies in newly diagnosed T1D patients (n=676) and controls (n=309). Patients, 0-18 years of age, diagnosed with T1D in 1996-2005 were analyzed for LVAb, HLA-DQ genotypes, and all seven known islet autoantibodies (GADA, IA-2A, IAA, ICA, ZnT8RA, ZnT8WA, and ZnT8QA). LVAb at 75(th) percentile, defined as cut off, was 90 (range 6-3936) U/mL and 4(th) quartile LVAb were found in 25% (170/676) of which 64% were <10 (n=108, p<0.0001), and 27% were<5 (n=45; p<0.0001) years old. The 4(th) quartile LVAb in children <10 years of age correlated to HLA DQ2/8, 8/8, and 8/X (p<0.0001). Furthermore, in the group with 4(th) quartile LVAb, 55% were IAA positive (p=0.01) and correlation was found between 4(th) quartile LVAb and IAA in children <10 years of age (p=0.035). It is concluded that 1) LVAb were common among the young T1D patients and LVAb levels were higher in the younger age groups; 2) 4(th) quartile LVAb correlated with IAA; and 3) there was a correlation between 4(th) quartile LVAb and HLA-DQ8, particularly in the young patients. The presence of LVAb supports the notion that prior exposure to LV may be associated with T1D.

HTR1A a novel type 1 diabetes susceptibility gene on chromosome 5p13-q13.

BACKGROUND: We have previously performed a genome-wide linkage study in Scandinavian Type 1 diabetes (T1D) families. In the Swedish families, we detected suggestive linkage (LOD≤2.2) to the chromosome 5p13-q13 region. The aim of our study was to investigate the linked region in search for possible T1D susceptibility genes. METHODOLOGY/PRINCIPAL FINDINGS: Microsatellites were genotyped in the Scandinavian families to fine-map the previously linked region. Further, SNPs were genotyped in Swedish and Danish families as well as Swedish sporadic cases. In the Swedish families we detected genome-wide significant linkage to the 5-hydroxytryptamine receptor 1A (HTR1A) gene (LOD 3.98, p<9.8×10(-6)). Markers tagging two separate genes; the ring finger protein 180 (RNF180) and HTR1A showed association to T1D in the Swedish and Danish families (p<0.002, p<0.001 respectively). The association was not confirmed in sporadic cases. Conditional analysis indicates that the primary association was to HTR1A. Quantitative PCR show that transcripts of both HTR1A and RNF180 are present in human islets of Langerhans. Moreover, immunohistochemical analysis confirmed the presence of the 5-HTR1A protein in isolated human islets of Langerhans as well as in sections of human pancreas. CONCLUSIONS: We have identified and confirmed the association of both HTR1A and RFN180, two genes in high linkage disequilibrium (LD) to T1D in two separate family materials. As both HTR1A and RFN180 were expressed at the mRNA level and HTR1A as protein in human islets of Langerhans, we suggest that HTR1A may affect T1D susceptibility by modulating the initial autoimmune attack or either islet regeneration, insulin release, or both.

Seroconversion to islet autoantibodies between early pregnancy and delivery in non-diabetic mothers.

Islet autoantibodies are currently used to classify type 1 diabetes at diagnosis as they reflect the autoimmune pathogenesis of the disease. The presence of maternal autoantibodies reactive with pancreatic islet antigens is thought to increase the risk for type 1 diabetes in the offspring. The objective of this study was to determine seroconversion to islet autoantibodies in non-diabetic mothers during pregnancy. Screening of 33,682 mothers between September 2000 and August 2004 in the Diabetes Prediction in Skåne (DiPiS) study showed that at delivery, 242 non-diabetic mothers had increased titers of islet autoantibodies reactive with glutamic acid decarboxylase (GADA), islet antigen-2 (IA-2A) or insulin (IAA), alone or in combination. Control mothers (n=1419), who were islet autoantibody negative at delivery, were randomly selected and matched by age, parity and pregnancy sampling date. Mothers positive for GADA (92%), IA-2A (84%) or IAA (65%) at delivery had increased titers already evident in early pregnancy. Titers declined for GADA (p<0.0001), IA-2A (p<0.0001) and IAA (p<0.0001). Seroconversion during pregnancy was observed for GADA in 10 (8%), IA-2A in 3 (16%) and IAA in 37 (35%) mothers. It is concluded that non-diabetic mothers with islet autoantibodies at delivery had significantly higher titers during early pregnancy than at delivery. As the statistical power in the seroconverting mothers was insufficient, further studies are needed to determine if the risk for type 1 diabetes in the offspring differs between mothers who already had increased titers of islet autoantibodies during early pregnancy or acquired them during pregnancy.

Maternal enterovirus infection during pregnancy as a risk factor in offspring diagnosed with type 1 diabetes between 15 and 30 years of age.

Maternal enterovirus infections during pregnancy may increase the risk of offspring developing type 1 diabetes during childhood. The aim of this study was to investigate whether gestational enterovirus infections increase the offspring's risk of type 1 diabetes later in life. Serum samples from 30 mothers without diabetes whose offspring developed type 1 diabetes between 15 and 25 years of age were analyzed for enterovirus-specific immunoglobulin M (IgM) antibodies and enterovirus genome (RNA), and compared to a control group. Among the index mothers, 9/30 (30%) were enterovirus IgM-positive, and none was positive for enterovirus RNA. In the control group, 14/90 (16%) were enterovirus IgM-positive, and 4/90 (4%) were positive for enterovirus RNA (n.s.). Boys of enterovirus IgM-positive mothers had approximately 5 times greater risk of developing diabetes (OR 4.63; 95% CI 1.22-17.6), as compared to boys of IgM-negative mothers (P < .025). These results suggest that gestational enterovirus infections may be related to the risk of offspring developing type 1 diabetes in adolescence and young adulthood.

Autoantibodies against soluble and immobilized human recombinant tissue transglutaminase in children with celiac disease.

OBJECTIVES: The conformation of tissue transglutaminase might influence the performance of immunoassays to detect autoantibodies from patients with celiac disease. The present study investigated how the exposure of tissue transglutaminase kept in a liquid phase and fixed to a solid support affected the binding of immunoglobulin (Ig)A and IgG autoantibodies in children with untreated and treated celiac disease. METHODS: Included were 73 untreated celiac disease children, 50 controls and 80 children with treated celiac disease. IgA and IgG antitissue transglutaminase were measured with solid phase enzyme-linked immunoassay (ELISA) and liquid phase radioligand binding assays. For IgG antitissue transglutaminase detection with radioligand binding assays antihuman IgG and protein A were used. IgA endomysial autoantibodies were measured by indirect immunofluorescence. RESULTS: Both ELISA and radioligand binding assays detected IgA antitissue transglutaminase in 65 of 73 untreated celiac disease children and in 2 of 50 controls. One additional control child was detected with radioligand binding assays. Endomysial autoantibodies were present in 62 of 73 celiac disease children and in 2 of 50 controls. IgG antitissue transglutaminase was detected with both ELISA and radioligand binding assays in 40 of 73 untreated celiac disease children and in 2 of 50 controls. Radioligand binding assays using protein A detected 20 of 73 additional untreated celiac disease children and one control child with increased IgG antitissue transglutaminase. In treated celiac disease children, 21 of 80 were IgA antitissue transglutaminase positive with radioligand binding assays, 3 of 80 with ELISA, whereas none had endomysial autoantibodies. CONCLUSIONS: No qualitative differences between radioligand binding assays and ELISA in IgA or IgG antitissue transglutaminase binding from untreated celiac disease children was demonstrated. However, discrepancies in the binding of IgA antitissue transglutaminase from a subgroup of treated celiac disease children indicated that alterations of tissue transglutaminase might occur on fixation of the antigen. Protein A used for radioligand binding assays seemed not to assess IgG autoantibodies exclusively. IgA antitissue transglutaminase detection in screening of childhood celiac disease can be performed either by ELISA or radioligand binding assays because the two assays are interchangeable.