Variation in Microbiome LPS Immunogenicity Contributes to Autoimmunity in Humans

According to the hygiene hypothesis, the increasing incidence of autoimmune diseases in western countries may be explained by changes in early microbial exposure, leading to altered immune maturation. We followed gut microbiome development from birth until age three in 222 infants in Northern Europe, where early-onset autoimmune diseases are common in Finland and Estonia but are less prevalent in Russia. We found that Bacteroides species are lowly abundant in Russians but dominate in Finnish and Estonian infants. Therefore, their lipopolysaccharide (LPS) exposures arose primarily from Bacteroides rather than from Escherichia coli, which is a potent innate immune activator. We show that Bacteroides LPS is structurally distinct from E. coli LPS and inhibits innate immune signaling and endotoxin tolerance; furthermore, unlike LPS from E. coli, B. dorei LPS does not decrease incidence of autoimmune diabetes in non-obese diabetic mice. Early colonization by immunologically silencing microbiota may thus preclude aspects of immune education.

Reduced β-cell function in early preclinical type 1 diabetes

OBJECTIVE

We aimed to characterize insulin responses to i.v. glucose during the preclinical period of type 1 diabetes starting from the emergence of islet autoimmunity.

DESIGN AND METHODS

A large population-based cohort of children with HLA-conferred susceptibility to type 1 diabetes was observed from birth. During regular follow-up visits islet autoantibodies were analysed. We compared markers of glucose metabolism in sequential intravenous glucose tolerance tests between 210 children who were positive for multiple (≥2) islet autoantibodies and progressed to type 1 diabetes (progressors) and 192 children testing positive for classical islet-cell antibodies only and remained healthy (non-progressors).

RESULTS

In the progressors, the first phase insulin response (FPIR) was decreased as early as 4-6 years before the diagnosis when compared to the non-progressors (P=0.001). The difference in FPIR between the progressors and non-progressors was significant (P<0.001) in all age groups, increasing with age (at 2 years: difference 50% (95% CI 28-75%) and at 10 years: difference 172% (95% CI 128-224%)). The area under the 10-min insulin curve showed a similar difference between the groups (P<0.001; at 2 years: difference 36% (95% CI 17-58%) and at 10 years: difference 186% (95% CI 143-237%)). Insulin sensitivity did not differ between the groups.

CONCLUSIONS

FPIR is decreased several years before the diagnosis of type 1 diabetes, implying an intrinsic defect in β-cell mass and/or function.

Serum 25-Hydroxyvitamin D Concentrations in Children Progressing to Autoimmunity and Clinical Type 1 Diabetes

CONTEXT

The role of vitamin D in the development of type 1 diabetes (T1D) remains controversial.

OBJECTIVE

The objective of the investigation was to study whether there are detectable differences in serum 25-hydroxyvitamin D (25[OH]D) concentrations between children who later progressed to T1D (cases) and matched children who remained nondiabetic and negative for islet autoantibodies (controls) when followed up from birth until disease onset.

DESIGN

A total of 3702 prospective serum samples from 252 children were measured for 25(OH)D from the age of 3 months onward using an enzyme immunoassay. Differences between the groups were compared by the mixed-model analysis of variance.

SETTING

T1D prediction and prevention study clinics in Turku, Oulu, and Tampere University Hospitals, Finland, participated in the study.

PARTICIPANTS

By the end of 2012, all 126 case children were diagnosed with T1D. The control children (n = 126) were matched for age, sex, study site, and human leukocyte antigen-HLA-DQ-conferred risk for T1D.

MAIN OUTCOME MEASURE

Median circulating 25(OH)D concentration (nanomoles per liter) was measured.

RESULTS

The patterns of variation in circulating 25(OH)D concentrations were similar between cases and controls and did not correlate with the age at seroconversion to autoantibody positivity (P = .79) or disease onset (P = .13). The median concentration of all collected samples did not differ between case and control children (66.6 nmol/L [range 14.0-262.8] vs 67.4 nmol/L [range 19.9-213.0]) P = .56).

CONCLUSIONS

This study shows that serum 25(OH)D concentrations are not associated with the development of T1D in Finland.

Positivity for Zinc Transporter 8 Autoantibodies at Diagnosis Is Subsequently Associated With Reduced β-Cell Function and Higher Exogenous Insulin Requirement in Children and Adolescents With Type 1 Diabetes

OBJECTIVE

This study assessed the relationship between autoantibodies against zinc transporter 8 (ZnT8A) and disease characteristics at diagnosis of type 1 diabetes and during the first 2 years.

RESEARCH DESIGN AND METHODS

Children, younger than 15 years of age (n = 723) who were newly diagnosed with diabetes, were analyzed for ZnT8A, other diabetes-associated autoantibodies, HLA DR-DQ alleles, and metabolic status, which was monitored by pH, plasma glucose, and occurrence of ketoacidosis at diagnosis and through follow-up of C-peptide concentrations, exogenous insulin dose, and glycosylated hemoglobin for 2 years after the diagnosis.

RESULTS

ZnT8A positivity was detected in 530 children (73%). Positivity for ZnT8A was associated with older age (median 8.9 vs. 8.2 years, P = 0.002) and more frequent ketoacidosis (24% vs. 15%, P = 0.013). Children carrying the HLA DR3 allele were less often ZnT8A positive (66% vs. 77%, P = 0.002) than others. ZnT8A-positive children had lower serum C-peptide concentrations (P = 0.008) and higher insulin doses (P = 0.012) over time than their ZnT8A-negative peers.

CONCLUSIONS

Positivity for ZnT8A at diagnosis seems to reflect a more aggressive disease process before and after diagnosis.

Food consumption and risk of childhood asthma

BACKGROUND

The consumption of foods rich in n-3 polyunsaturated fatty acids has been proposed to protect against childhood asthma. This study explores the association of food consumption (including cow's milk (CM)-free diet) in early life and the risk of atopic and non-atopic asthma.

METHODS

Food intake of 182 children with asthma and 728 matched controls was measured using 3-day food records, within the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) Nutrition Study cohort. The diagnoses of food allergies came both from the written questionnaire and from the registers of the Social Insurance Institution. Conditional logistic regression with generalized estimating equations framework was used in the analyses.

RESULTS

The diagnosis of cow's milk allergy (CMA) led to multiple dietary restrictions still evident at 4 yr of age. Even after adjusting for CMA, higher consumption of CM products was inversely associated with the risk of atopic asthma and higher consumption of breast milk and oats inversely with the risk of non-atopic asthma. Early consumption of fish was associated with a decreased risk of all asthma.

CONCLUSIONS

Dietary intake in early life combined with atopy history has a clear impact on the risk of developing asthma. Our results indicate that CM restriction due to CMA significantly increases and mediates the association between food consumption and childhood asthma risk.

Influenza A virus antibodies show no association with pancreatic islet autoantibodies in children genetically predisposed to type 1 diabetes

AIMS/HYPOTHESIS

Viral infections have long been considered potential triggers of beta cell autoimmunity and type 1 diabetes. Recent studies have suggested that influenza A virus might increase the risk of type 1 diabetes. The present study evaluates this risk association in prospectively observed children at the time when islet autoimmunity starts and autoantibodies are first detected.

METHODS

IgG class antibodies to influenza A virus were analysed in 95 case children whose antibody screening test turned permanently positive for two or more islet autoantibodies and from 186 autoantibody-negative and non-diabetic control children who were matched for time of birth, sex, date of sampling and HLA-conferred risk of diabetes in the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) study. Virus antibodies were measured from the first autoantibody-positive sample using an enzyme immunoassay. None of the children had been vaccinated against influenza A.

RESULTS

The prevalence of influenza A virus antibodies did not differ between the case and control children (42% vs 38%; p = 0.392) and the median antibody levels were also comparable in the two groups (3.0 vs 3.8 enzyme immunoassay units). A similar result was obtained when case and control children were compared separately in subgroups according to different sex, age and HLA-DQ genotype. However, girls had higher antibody levels than boys among both case and control children (median antibody levels 9.0 vs 2.3 enzyme immunoassay units; p = 0.01).

CONCLUSIONS/INTERPRETATION

Our results suggest that influenza A infections are not associated with the development of islet autoimmunity in young children with increased genetic susceptibility to type 1 diabetes.

B-Cell Responses to Human Bocaviruses 1-4: New Insights from a Childhood Follow-Up Study

Human bocaviruses (HBoVs) 1-4 are recently discovered, antigenically similar parvoviruses. We examined the hypothesis that the antigenic similarity of these viruses could give rise to clinically and diagnostically important immunological interactions. IgG and IgM EIAs as well as qPCR were used to study ~2000 sera collected from infancy to early adolescence at 3-6-month intervals from 109 children whose symptoms were recorded. We found that HBoV1-4-specific seroprevalences at age 6 years were 80%, 48%, 10%, and 0%, respectively. HBoV1 infections resulted in significantly weaker IgG responses among children who had pre-existing HBoV2 IgG, and vice versa. Furthermore, we documented a complete absence of virus type-specific immune responses in six viremic children who had pre-existing IgG for another bocavirus, indicating that not all HBoV infections can be diagnosed serologically. Our results strongly indicate that interactions between consecutive HBoV infections affect HBoV immunity via a phenomenon called "original antigenic sin", cross-protection, or both; however, without evident clinical consequences but with important ramifications for the serodiagnosis of HBoV infections. Serological data is likely to underestimate human exposure to these viruses.

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.

OGTT and random plasma glucose in the prediction of type 1 diabetes and time to diagnosis

AIMS/HYPOTHESIS

We assessed the utility of the OGTT and random plasma glucose concentrations in predicting the time to diagnosis of type 1 diabetes.

METHODS

A population-derived cohort of 14,876 newborns with HLA-conferred risk of type 1 diabetes were invited to regular follow-up for islet autoantibodies. When two or more autoantibodies were detected, an OGTT was performed once a year and random plasma glucose analysed twice a year. During follow-up, 567 children developed multiple autoantibodies, 255 (45%) of whom were diagnosed with type 1 diabetes, while 312 remained non-diabetic by December 2011.

RESULTS

Impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) were risk factors for type 1 diabetes (HR 3.2 [95% CI 1.5, 7.0] and 8.3 [95% CI 6.0, 11.5], respectively). When a random plasma glucose value ≥ 7.8 mmol/l was observed, the HR for diabetes was 6.0 (95% CI 4.3, 8.6). The median time to diagnosis after the detection of IFG was 5.2 years (interquartile range [IQR] 3.4, 6.3); after IGT, 0.7 years (IQR 0.3, 1.9); and, after a random plasma glucose ≥ 7.8 mmol/l, 1.0 years (IQR 0.3, 1.5). In a retrospective analysis, both OGTT-derived 2 h plasma glucose and random plasma glucose started to increase 1.5 years before diagnosis (p < 0.001 and p = 0.004, respectively).

CONCLUSIONS/INTERPRETATION

Dysglycaemia detected in an OGTT or based on random plasma glucose is a useful marker in the prediction of time to onset of type 1 diabetes in high-risk children. Random plasma glucose is a simple and low-cost measurement with comparable predictive characteristics to that of OGTT-derived 2 h glucose.

Circulating IGF1 and IGFBP3 in relation to the development of β-cell autoimmunity in young children

OBJECTIVE

This study aimed at investigating the role of IGF1 and IGF binding protein 3 (IGFBP3) in the development of β-cell autoimmunity.

METHODS

Five hundred and sixty-three subjects with HLA-conferred susceptibility to type 1 diabetes (T1D) were monitored for signs of seroconversion to positivity for insulin and/or GAD, IA2, and zinc transporter 8 autoantibodies by the age of 3 years. In 40 subjects who developed at least one autoantibody, IGF1 and IGFBP3 plasma concentrations were measured and compared with 80 control subjects who remained negative for autoantibodies, and were matched for age, sex, country of origin, and HLA genotype. The increments of IGF1, IGFBP3, and IGF1/IGFBP3 molar ratio before and after seroconverison were compared with corresponding time intervals in controls.

RESULTS

The IGF1 concentrations at the age of 12 months and the IGF1/IGFBP3 ratio at the age of 24 months were lower in the autoantibody-positive children (P<0.05). The increase in circulating IGFBP3 was significantly higher in the autoantibody-positive children before seroconversion than in the corresponding time intervals in controls (0.43 mg/l; 95% CI 0.29-0.56 vs 0.22 mg/l; 95% CI 0.10-0.34 mg/l; P<0.01). Children carrying the high-risk HLA genotype had lower plasma IGF1 and IGFBP3 concentrations at the age of 24 months than those with low-risk genotypes (P<0.05 and < 0.01 respectively).

CONCLUSIONS

Circulating IGF1 and IGFBP3 appear to have a role in early development of β-cell autoimmunity. The decreased IGF1 concentrations in children with the high-risk HLA genotype may contribute to the reduced growth previously described in such children.

Non-HLA gene effects on the disease process of type 1 diabetes: From HLA susceptibility to overt disease

In addition to the HLA region numerous other gene loci have shown association with type 1 diabetes. How these polymorphisms exert their function has not been comprehensively described, however. We assessed the effect of 39 single nucleotide polymorphisms (SNP) on the development of autoantibody positivity, on progression from autoantibody positivity to clinical disease and on the specificity of the antibody initiating the autoimmune process in 521 autoantibody-positive and 989 control children from a follow-up study starting from birth. Interestingly, PTPN2 rs45450798 gene polymorphism was observed to strongly affect the progression rate of beta-cell destruction after the appearance of humoral beta-cell autoimmunity. Moreover, primary autoantigen dependent associations were also observed as effect of the IKZF4-ERBB3 region on the progression rate of β-cell destruction was restricted to children with GAD antibodies as their first autoantibody whereas the effect of the INS rs 689 polymorphism was observed among subjects with insulin as the primary autoantigen. In the whole study cohort, INS rs689, PTPN22 rs2476601 and IFIH1 rs1990760 polymorphisms were associated with the appearance of beta-cell autoantibodies. These findings provide new insights into the role of genetic factors implicated in the pathogenesis of type 1 diabetes. The effect of some of the gene variants is restricted to control the initiation of β-cell autoimmunity whereas others modify the destruction rate of the β-cells. Furthermore, signs of primary autoantigen-related pathways were detected.

Serum proteomes distinguish children developing type 1 diabetes in a cohort with HLA-conferred susceptibility

We determined longitudinal serum proteomics profiles from children with HLA-conferred diabetes susceptibility to identify changes that could be detected before seroconversion and positivity for disease-associated autoantibodies. Comparisons were made between children who seroconverted and progressed to type 1 diabetes (progressors) and those who remained autoantibody negative, matched by age, sex, sample periodicity, and risk group. The samples represented the prediabetic period and ranged from the age of 3 months to 12 years. After immunoaffinity depletion of the most abundant serum proteins, isobaric tags for relative and absolute quantification were used for sample labeling. Quantitative proteomic profiles were then measured for 13 case-control pairs by high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). Additionally, a label-free LC-MS/MS approach was used to analyze depleted sera from six case-control pairs. Importantly, differences in abundance of a set of proteins were consistently detected before the appearance of autoantibodies in the progressors. Based on top-scoring pairs analysis, classification of such progressors was observed with a high success rate. Overall, the data provide a reference of temporal changes in the serum proteome in healthy children and children progressing to type 1 diabetes, including new protein candidates, the levels of which change before clinical diagnosis.

GIMAP GTPase family genes: potential modifiers in autoimmune diabetes, asthma, and allergy

GTPase of the immunity-associated protein (GIMAP) family members are differentially regulated during human Th cell differentiation and have been previously connected to immune-mediated disorders in animal studies. GIMAP4 is believed to contribute to the Th cell subtype-driven immunological balance via its role in T cell survival. GIMAP5 has a key role in BB-DR rat and NOD mouse lymphopenia. To elucidate GIMAP4 and GIMAP5 function and role in human immunity, we conducted a study combining genetic association in different immunological diseases and complementing functional analyses. Single nucleotide polymorphisms tagging the GIMAP haplotype variation were genotyped in Finnish type 1 diabetes (T1D) families and in a prospective Swedish asthma and allergic sensitization birth cohort. Initially, GIMAP5 rs6965571 was associated with risk for asthma and allergic sensitization (odds ratio [OR] 3.74, p = 0.00072, and OR 2.70, p = 0.0063, respectively) and protection from T1D (OR 0.64, p = 0.0058); GIMAP4 rs13222905 was associated with asthma (OR 1.28, p = 0.035) and allergic sensitization (OR 1.27, p = 0.0068). However, after false discovery rate correction for multiple testing, only the associations of GIMAP4 with allergic sensitization and GIMAP5 with asthma remained significant. In addition, transcription factor binding sites surrounding the associated loci were predicted. A gene-gene interaction in the T1D data were observed between the IL2RA rs2104286 and GIMAP4 rs9640279 (OR 1.52, p = 0.0064) and indicated between INS rs689 and GIMAP5 rs2286899. The follow-up functional analyses revealed lower IL-2RA expression upon GIMAP4 knockdown and an effect of GIMAP5 rs2286899 genotype on protein expression. Thus, the potential role of GIMAP4 and GIMAP5 as modifiers of immune-mediated diseases cannot be discarded.

Gut virome sequencing in children with early islet autoimmunity

OBJECTIVE

This study used next-generation sequencing (NGS) technologies to characterize the gut virome at the onset of islet autoimmunity.

RESEARCH DESIGN AND METHODS

We conducted a case-control study nested within the Finnish Diabetes Prediction and Prevention (DIPP) cohort. The stool virome in 19 case children, who turned islet autoantibody positive before the age of 2 years and later developed clinical type 1 diabetes, and 19 tightly matched control subjects was analyzed using NGS performed from stool samples collected 3, 6, and 9 months before the onset of islet autoimmunity. Human virus findings were verified using real-time PCR.

RESULTS

One or more human viruses were present in 10.4% and bacteriophages were in 54% of the samples. The virome composition showed no association with islet autoimmunity. NGS was less sensitive and specific than real-time PCR.

CONCLUSIONS

The present data suggest no dramatic changes in the gut virome shortly before the emergence of islet autoimmunity and emphasize the need of verification of mass sequencing results when viral exposure is assessed in association studies.

CD4⁺ T-cell proliferation responses to wheat polypeptide stimulation in children at different stages of type 1 diabetes autoimmunity

AIMS

Our aim was to study whether immune responses to wheat-based proteins are related to the development of type 1 diabetes.

METHODS

We analysed proliferative T-cell responses after in vitro gliadin, gluten, whole wheat, and tetanus toxoid stimulation with a carboxyfluorescein succinimidyl ester (CFSE) based T-cell proliferation assay in children at various phases of type 1 diabetes autoimmunity and in healthy autoantibody-negative control children.

RESULTS

At an early stage of beta cell autoimmunity the strength and frequencies of positive proliferation responses to gliadin, gluten, and whole wheat did not differ between newly seroconverted children positive for one islet autoantibody and the controls. However, in prediabetic children with at least two islet autoantibodies and also in children with newly diagnosed type 1 diabetes positive T-cell responses to gliadin were significantly less frequent and the strength of gliadin responses was reduced when compared to the controls. No differences were seen in T-cell responses to wheat-based antigens when comparing children with long-lasting type 1 diabetes with healthy controls.

CONCLUSIONS/INTERPRETATION

Decreased in vitro T-cell responses to wheat-based antigens were observed in children with multiple islet autoantibodies and in those with newly diagnosed type 1 diabetes, probably reflecting a generally aberrant immune response during the development of type 1 diabetes.

HbA1c Predicts Time to Diagnosis of Type 1 Diabetes in Children at Risk

Prediction of type 1 diabetes is based on the detection of multiple islet autoantibodies in subjects who are at increased genetic risk. Prediction of the timing of diagnosis is challenging, however. We assessed the utility of HbA1c levels in predicting the clinical disease in genetically predisposed children with multiple autoantibodies. Cord blood samples from 168,055 newborn infants were screened for class II HLA genotypes in Finland, and 14,876 children with increased genetic risk for type 1 diabetes were invited to participate in regular follow-ups, including screening for diabetes-associated autoantibodies. When two or more autoantibodies were detected, HbA1c levels were analyzed at each visit. During follow-up, multiple (two or more) autoantibodies developed in 466 children; type 1 diabetes was diagnosed in 201 of these children (43%, progressors), while 265 children remained disease free (nonprogressors) by December 2011. A 10% increase in HbA1c levels in samples obtained 3-12 months apart predicted the diagnosis of clinical disease (hazard ratio [HR] 5.7 [95% CI 4.1-7.9]) after a median time of 1.1 years (interquartile range [IQR] 0.6-3.1 years) from the observed rise of HbA1c. If the HbA1c level was ≥5.9% (41 mmol/mol) in two consecutive samples, the median time to diagnosis was 0.9 years (IQR 0.3-1.5, HR 11.9 [95% CI 8.8-16.0]). In conclusion, HbA1c is a useful biochemical marker when predicting the time to diagnosis of type 1 diabetes in children with multiple autoantibodies.

Role of Type 1 Diabetes-Associated SNPs on Risk of Autoantibody Positivity in the TEDDY Study

The Environmental Determinants of Diabetes in the Young (TEDDY) study prospectively follows 8,677 children enrolled from birth who carry HLA-susceptibility genotypes for development of islet autoantibodies (IA) and type 1 diabetes (T1D). During the median follow-up time of 57 months, 350 children developed at least one persistent IA (GAD antibody, IA-2A, or micro insulin autoantibodies) and 84 of them progressed to T1D. We genotyped 5,164 Caucasian children for 41 non-HLA single nucleotide polymorphisms (SNPs) that achieved genome-wide significance for association with T1D in the genome-wide association scan meta-analysis conducted by the Type 1 Diabetes Genetics Consortium. In TEDDY participants carrying high-risk HLA genotypes, eight SNPs achieved significant association to development of IA using time-to-event analysis (P < 0.05), whereof four were significant after adjustment for multiple testing (P < 0.0012): rs2476601 in PTPN22 (hazard ratio [HR] 1.54 [95% CI 1.27-1.88]), rs2292239 in ERBB3 (HR 1.33 [95% CI 1.14-1.55]), rs3184504 in SH2B3 (HR 1.38 [95% CI 1.19-1.61]), and rs1004446 in INS (HR 0.77 [0.66-0.90]). These SNPs were also significantly associated with T1D in particular: rs2476601 (HR 2.42 [95% CI 1.70-3.44]). Although genes in the HLA region remain the most important genetic risk factors for T1D, other non-HLA genetic factors contribute to IA, a first step in the pathogenesis of T1D, and the progression of the disease.

The 6 year incidence of diabetes-associated autoantibodies in genetically at-risk children: the TEDDY study

AIMS/HYPOTHESIS

Islet autoantibodies, in addition to elevated blood glucose, define type 1 diabetes. These autoantibodies are detectable for a variable period of time before diabetes onset. Thus, the occurrence of islet autoantibodies is associated with the beginning of the disease process. The age at, and order in, which autoantibodies appear may be associated with different genetic backgrounds or environmental exposures, or both.

METHODS

Infants with HLA-DR high-risk genotypes (DR3/4, DR4/4, DR4/8 and DR3/3) were enrolled and prospectively followed with standardised autoantibody assessments quarterly throughout the first 4 years of life and then semi-annually thereafter.

RESULTS

Autoantibodies appeared in 549/8,503 (6.5%) children during 34,091 person-years of follow-up. Autoantibodies at 3 (0.1%) and 6 (0.2%) months of age were rare. Of the 549, 43.7% had islet autoantibodies to insulin (IAA) only, 37.7% had glutamic acid decarboxylase autoantibodies (GADA) only, 13.8% had both GADA and IAA only, 1.6% had insulinoma antigen-2 only and 3.1% had other combinations. The incidence of IAA only peaked within the first year of life and declined over the following 5 years, but GADA only increased until the second year and remained relatively constant. GADA only were more common than IAA only in HLA-DR3/3 children but less common in HLA-DR4/8 children.

CONCLUSIONS/INTERPRETATION

Islet autoantibodies can occur very early in life and the order of appearance was related to HLA-DR-DQ genotype.

Decrease in circulating concentrations of soluble receptors for advanced glycation end products at the time of seroconversion to autoantibody positivity in children with prediabetes

OBJECTIVE

Dietary advanced glycation end products (AGEs) and their interactions with the receptor for AGEs (RAGE) may play a role in the pathogenesis of type 1 diabetes. This study set out to assess whether there is any association of circulating concentrations of soluble RAGE (sRAGE), AGEs, and their ratio with the appearance of diabetes-associated autoantibodies in children progressing to clinical diabetes.

RESEARCH DESIGN AND METHODS

Serum concentrations of sRAGE, N-ε(carboxymethyl)lysine (CML) adducts, and the sRAGE/CML ratio were analyzed in children who progressed to type 1 diabetes. The samples were taken at four time points: before seroconversion, at the time of the first autoantibody-positive sample, at the time of the first sample positive for multiple (>2) autoantibodies, and close to the disease diagnosis. Samples of autoantibody-negative controls matched for age, sex, and HLA-conferred diabetes risk were analyzed at corresponding time points.

RESULTS

The prediabetic children had higher sRAGE concentrations before seroconversion (Pc = 0.03), at the appearance of multiple autoantibodies (Pc = 0.008), and close to diagnosis (Pc = 0.04). Close to diagnosis, the cases had lower CML concentrations than the controls (Pc = 0.004). Prediabetic children had a higher sRAGE/CML ratio than the controls before seroconversion (Pc = 0.008) and at diagnosis (Pc < 0.001).

CONCLUSIONS

Prediabetic children have higher concentrations of sRAGE and a higher sRAGE/CML ratio than healthy controls. Circulating sRAGE concentrations seem to decline with the appearance of diabetes-predictive autoantibodies in children progressing to type 1 diabetes. The higher sRAGE/CML ratio in prediabetic children may reflect a higher AGE scavenger capacity.

Age-associated DNA methylation changes in immune genes, histone modifiers and chromatin remodeling factors within 5 years after birth in human blood leukocytes

Background

Age-related changes in DNA methylation occurring in blood leukocytes during early childhood may reflect epigenetic maturation. We hypothesized that some of these changes involve gene networks of critical relevance in leukocyte biology and conducted a prospective study to elucidate the dynamics of DNA methylation. Serial blood samples were collected at 3, 6, 12, 24, 36, 48 and 60 months after birth in ten healthy girls born in Finland and participating in the Type 1 Diabetes Prediction and Prevention Study. DNA methylation was measured using the HumanMethylation450 BeadChip.

Results

After filtering for the presence of polymorphisms and cell-lineage-specific signatures, 794 CpG sites showed significant DNA methylation differences as a function of age in all children (41.6% age-methylated and 58.4% age-demethylated, Bonferroni-corrected P value <0.01). Age-methylated CpGs were more frequently located in gene bodies and within +5 to +50 kilobases (kb) of transcription start sites (TSS) and enriched in developmental, neuronal and plasma membrane genes. Age-demethylated CpGs were associated to promoters and DNAse-I hypersensitivity sites, located within −5 to +5 kb of the nearest TSS and enriched in genes related to immunity, antigen presentation, the polycomb-group protein complex and cytoplasm.

Conclusions

This study reveals that susceptibility loci for complex inflammatory diseases (for example, IRF5, NOD2, and PTGER4) and genes encoding histone modifiers and chromatin remodeling factors (for example, HDAC4, KDM2A, KDM2B, JARID2, ARID3A, and SMARCD3) undergo DNA methylation changes in leukocytes during early childhood. These results open new perspectives to understand leukocyte maturation and provide a catalogue of CpG sites that may need to be corrected for age effects when performing DNA methylation studies in children.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-015-0064-6) contains supplementary material, which is available to authorized users.

Risk genes and autoantibodies in Egyptian children with type 1 diabetes - low frequency of autoantibodies in carriers of the HLA-DRB1*04:05-DQA1*03-DQB1*02 risk haplotype

BACKGROUND

The study aimed to define the frequencies of type 1 diabetes-associated gene polymorphisms and their associations with various diabetes-associated autoantibodies in Egyptian children.

METHODS

One hundred and one children with type 1 diabetes and 160 healthy controls from the same region were studied for HLA-DQB1, HLA-DQA1, and HLA-DRB1 (DR4 subtypes) alleles; for INS and protein tyrosine phosphatase, non-receptor type 22 gene polymorphisms (rs689 and rs2476601); and for diabetes-associated autoantibodies.

RESULTS

Most children with diabetes (77.2%) were positive for the HLA-(DR3)-DQA1*05-DQB1*02 (DR3-DQ2) haplotype compared with 26.2% of the controls (OR = 9.5; p < 0.001). HLA-DRB1*04:02-DQA1*03-DQB1*03:02 (DR4-DQ8) (26.7%, OR = 3.3; p < 0.001), DRB1*04:05-DQA1*03-DQB1*02 (DR4-DQ2) (23.8%, OR 5.2; p < 0.001), and DRB1*04:05-DQA1*03-DQB1*03:02 (DR4-DQ8) (8.9%, OR = 7.7; p = 0.007) were also significantly increased. HLA-(DR15)-DQB1*06:01, (DR13)-DQB1*06:03, and DRB1*04:03-DQA1*03-DQB1*03:02 were the most protective haplotypes with OR values from 0.04 to 0.06. Patients positive for DR3-DQ2 but negative for DR4 haplotypes had a high frequency of glutamic acid decarboxylase antibodies (78%; p < 0.001 versus other genotypes), but only 26.6% of those with DR3-DQ2/DR4-DQ2 tested positive for glutamic acid decarboxylase antibodies (p = 0.006 versus other genotypes). Subjects with the DR4-DQ8 haplotype without DR3-DQ2 or DR4-DQ2 were more often positive for islet antigen-2 and zinc transporter 8 antibodies (55.5%, p = 0.007 and 55.5%, p = 0.01 respectively). The AA genotype of the INS gene was more common in patients than in controls (75.2 versus 59.5%, OR = 2.07; p = 0.018).

CONCLUSIONS

Besides a strong HLA-DR3-DQ2 association, a relatively high frequency of the DR4-DQ2 haplotype characterized the diabetic population. The low frequency of autoantibodies in children with HLA-DR4-DQ2 may indicate specific pathogenetic pathways associated with this haplotype.

A novel common variant in DCST2 is associated with length in early life and height in adulthood

Common genetic variants have been identified for adult height, but not much is known about the genetics of skeletal growth in early life. To identify common genetic variants that influence fetal skeletal growth, we meta-analyzed 22 genome-wide association studies (Stage 1; N = 28 459). We identified seven independent top single nucleotide polymorphisms (SNPs) (P < 1 × 10(-6)) for birth length, of which three were novel and four were in or near loci known to be associated with adult height (LCORL, PTCH1, GPR126 and HMGA2). The three novel SNPs were followed-up in nine replication studies (Stage 2; N = 11 995), with rs905938 in DC-STAMP domain containing 2 (DCST2) genome-wide significantly associated with birth length in a joint analysis (Stages 1 + 2; β = 0.046, SE = 0.008, P = 2.46 × 10(-8), explained variance = 0.05%). Rs905938 was also associated with infant length (N = 28 228; P = 5.54 × 10(-4)) and adult height (N = 127 513; P = 1.45 × 10(-5)). DCST2 is a DC-STAMP-like protein family member and DC-STAMP is an osteoclast cell-fusion regulator. Polygenic scores based on 180 SNPs previously associated with human adult stature explained 0.13% of variance in birth length. The same SNPs explained 2.95% of the variance of infant length. Of the 180 known adult height loci, 11 were genome-wide significantly associated with infant length (SF3B4, LCORL, SPAG17, C6orf173, PTCH1, GDF5, ZNFX1, HHIP, ACAN, HLA locus and HMGA2). This study highlights that common variation in DCST2 influences variation in early growth and adult height.

The dynamics of the human infant gut microbiome in development and in progression toward type 1 diabetes

Colonization of the fetal and infant gut microbiome results in dynamic changes in diversity, which can impact disease susceptibility. To examine the relationship between human gut microbiome dynamics throughout infancy and type 1 diabetes (T1D), we examined a cohort of 33 infants genetically predisposed to T1D. Modeling trajectories of microbial abundances through infancy revealed a subset of microbial relationships shared across most subjects. Although strain composition of a given species was highly variable between individuals, it was stable within individuals throughout infancy. Metabolic composition and metabolic pathway abundance remained constant across time. A marked drop in alpha-diversity was observed in T1D progressors in the time window between seroconversion and T1D diagnosis, accompanied by spikes in inflammation-favoring organisms, gene functions, and serum and stool metabolites. This work identifies trends in the development of the human infant gut microbiome along with specific alterations that precede T1D onset and distinguish T1D progressors from nonprogressors.

Vitamin D3 administration to MS patients leads to increased serum levels of latency activated peptide (LAP) of TGF-beta

BACKGROUND

Deficiency of vitamin D is an environmental risk factor for MS. Vitamin D has immunomodulatory effects, including promotion of T-cell differentiation into T-regulatory cells, which produces regulatory cytokines including TGF-β. Increasing serum vitamin D levels have been associated with decreased disease activity in MS patients, but there are only few studies concerning the immunological effects of vitamin D supplementation in MS. In this study we investigated the effect of weekly supplementation of vitamin D3 or placebo on serum levels of multiple cytokines in patients with relapsing remitting MS.

METHODS

The study was conducted on the patient cohort of the Finnish Vitamin D study. All patients were using IFN-beta-1b and were randomized to add-on treatment with either cholecalciferol 20,000 IU/week or placebo. Concentrations of LAP (TGF-β), INF-γ, IL-17A, IL-2, IL-10, IL-9, IL-22, IL-6, IL-13, IL-4, IL-5, IL-1β and TNF-α were determined at screening and at 12 months using commercial fluorescent bead immunoassay kits.

RESULTS

LAP (TGF-β) levels increased significantly in the vitamin D treated group from a mean of 47 (SE 11) pg/ml to 55 (SE 14) pg/ml in 12 months (p-value=0.0249). Placebo treatment had no significant effect on LAP levels. The levels of the other cytokines did not change significantly in either group.

CONCLUSIONS

We showed increased serum latency activated peptide (LAP) of TGF-β levels in MS patients treated with vitamin D3. The immune regulatory effects of TGF-beta may play a role in the improved MRI outcomes that we observed earlier in the vitamin D treated group of patients.

Heterogeneity in diabetes-associated autoantibodies and susceptibility to Type 1 diabetes: lessons for disease prevention

Autoantibodies against pancreatic islets are strong predictors of Type 1 diabetes. When persistent β-cell autoantibodies against at least two autoantigens are detected, the probability of diabetes is extremely high, although the time period before disease development can vary from days up to more than 20 years. Insulin autoantibodies or antibodies specific to glutamate decarboxylase 65 enzyme are in most cases, the first autoantibodies to appear. Insulin autoantibodies typically emerge very early with a peak at the age of 1.5 years, whereas the onset of glutamic acid decarboxylase 65 antibody positivity has a more even distribution, peaking later in childhood. These differences in the timing of appearance suggest that different environmental factors might be involved in the initiation of β-cell autoimmunity beginning either already in infancy or later on. This should be taken into account in studies aimed at identifying environmental factors triggering islet cell-specific autoimmunity and also in the design of prevention trials.