Genetic risk factors for type 1 diabetes

Screening of monogenic autoimmune diabetes among children with type 1 diabetes and multiple autoimmune diseases: is it worth doing?

Background Paediatric type 1 diabetes (T1D) and rare syndromes of monogenic multi-organ autoimmunity share basic features such as full insulin dependency and the presence of circulating beta-cell autoantibodies. However, the aetiopathogenesis, natural course and treatment of these conditions differ; therefore, monogenic multi-organ autoimmunity requires early recognition. We aimed to search for these monogenic conditions among a large cohort of children with T1D. Methods Of 519 children with T1D followed-up in a single centre, 18 had multiple additional autoimmune conditions - either autoimmune thyroid disease (AITD) and coeliac disease (CD) or at least one additional organ-specific autoimmune condition in addition to AITD or CD. These 18 children were tested by direct Sanger sequencing (four patients with a suggestive phenotype of immune dysregulation, polyendocrinopathy, enteropathy, X-linked [IPEX] or signal transducer and activator of transcription 3 [STAT3]- and cytotoxic T-lymphocyte protein 4 [CTLA4]-associated syndromes) or by whole-exome sequencing (WES) focused on autoimmune regulator (AIRE), forkhead box protein 3 (FOXP3), CTLA4, STAT3, signal transducer and activator of transcription 1 (STAT1), lipopolysaccharide-responsive and beige-like anchor protein (LRBA) and interleukin-2 receptor subunit α (IL2RA) genes. In addition, we assessed their T1D genetic risk score (T1D-GRS). Results We identified novel variants in FOXP3, STAT3 and CTLA4 in four cases. All patients had a severe phenotype suggestive of a single gene defect. No variants were identified in the remaining 14 patients. T1D-GRS varied among the entire cohort; four patients had scores below the 25th centile including two genetically confirmed cases. Conclusions A monogenic cause of autoimmune diabetes was confirmed only in four patients. Genetic screening for monogenic autoimmunity in children with a milder phenotype and a combination of AITD and CD is unlikely to identify a monogenic cause. In addition, the T1D-GRS varied among individual T1D patients.

Endocrine-Related Adverse Events Related to Immune Checkpoint Inhibitors: Proposed Algorithms for Management

Immune checkpoint inhibitors have proven to be effective for various advanced neoplasia. Immune-related adverse events (irAEs) as a result of increased T cell activation are unique and potentially life-threating toxicities associated with the use of immune checkpoint inhibitors. Multiple endocrine irAEs, including primary hyperthyroidism and hypothyroidism, thyroiditis, primary adrenal insufficiency, type 1 diabetes mellitus, and hypophysitis, have been reported with the use of various immune checkpoint inhibitors. In some cases, these irAEs can lead to discontinuation of treatment. Here we propose for the general oncologist algorithms for managing endocrine irAEs to aid in the clinical care of patients receiving immunotherapy. KEY POINTS: There is a relative high risk of endocrine immune-related adverse events (irAEs) during therapy with checkpoint inhibitors, particularly when combination therapy is implemented. Patients treated with anti-CTLA-4 antibodies have an increased risk of hypophysitis, whereas patients treated with anti-PD-1/PD-L1 antibodies have a higher risk of primary thyroid dysfunction. Rarely, patients develop T1DM and central diabetes insipidus, and hypoparathyroidism is a rare occurrence. A growing clinical understanding of endocrine irAEs has led to effective treatment strategies with hormone replacement.

The Roles of Peyer's Patches and Microfold Cells in the Gut Immune System: Relevance to Autoimmune Diseases

Microfold (M) cells are located in the epithelium covering mucosa-associated lymphoid tissues, such as the Peyer's patches (PPs) of the small intestine. M cells actively transport luminal antigens to the underlying lymphoid follicles to initiate an immune response. The molecular machinery of M-cell differentiation and function has been vigorously investigated over the last decade. Studies have shed light on the role of M cells in the mucosal immune system and have revealed that antigen uptake by M cells contributes to not only mucosal but also systemic immune responses. However, M-cell studies usually focus on infectious diseases; the contribution of M cells to autoimmune diseases has remained largely unexplored. Accumulating evidence suggests that dysbiosis of the intestinal microbiota is implicated in multiple systemic diseases, including autoimmune diseases. This implies that the uptake of microorganisms by M cells in PPs may play a role in the pathogenesis of autoimmune diseases. We provide an outline of the current understanding of M-cell biology and subsequently discuss the potential contribution of M cells and PPs to the induction of systemic autoimmunity, beyond the mucosal immune response.

Onset of type 1 diabetes mellitus in rural areas of the USA

BACKGROUND

In the USA, the epidemiologic features of type 1 diabetes are not well-defined across all 50 states. However, the advent of large nationwide insurance databases enables the investigation of where type 1 diabetes cases occur throughout the country.

METHODS

An integrated database from a large nationwide health insurer in the USA (Clinformatics Data Mart Database) was used, from 2001 to 2017. The database contained longitudinal information on approximately 77 million people.

RESULTS

The incidence of type 1 diabetes was greatest in areas of low population density across the 50 states. Individuals in the lowest population density areas had rates that were 2.28 times (95% CI 2.08 to 2.50) that of persons living in high-density areas. This association was consistent across various measures of rural status (p<0.001 for population density; p<0.001 for per cent rural as defined by the US Census Bureau; p=0.026 for farmland). The association between rural areas and the incidence of type 1 diabetes was evident across all four general regions of the USA.

CONCLUSIONS

The predilection of type 1 diabetes in rural areas provides clues to potential factors associated with the onset of this autoimmune disease.

Influence of Vitamin D on Islet Autoimmunity and Beta-Cell Function in Type 1 Diabetes

Type 1 diabetes (T1D) is a chronic autoimmune disease leading to immune-mediated destruction of pancreatic beta cells, resulting in the need for insulin therapy. The incidence of T1D is increasing worldwide, thus prompting researchers to investigate novel immunomodulatory strategies to halt autoimmunity and modify disease progression. T1D is considered as a multifactorial disease, in which genetic predisposition and environmental factors interact to promote the triggering of autoimmune responses against beta cells. Over the last decades, it has become clear that vitamin D exerts anti-inflammatory and immunomodulatory effects, apart from its well-established role in the regulation of calcium homeostasis and bone metabolism. Importantly, the global incidence of vitamin D deficiency is also dramatically increasing and epidemiologic evidence suggests an involvement of vitamin D deficiency in T1D pathogenesis. Polymorphisms in genes critical for vitamin D metabolism have also been shown to modulate the risk of T1D. Moreover, several studies have investigated the role of vitamin D (in different doses and formulations) as a potential adjuvant immunomodulatory therapy in patients with new-onset and established T1D. This review aims to present the current knowledge on the immunomodulatory effects of vitamin D and summarize the clinical interventional studies investigating its use for prevention or treatment of T1D.

The influence of maternal body mass index, maternal diabetes mellitus, and maternal smoking during pregnancy on the risk of childhood-onset type 1 diabetes mellitus in the offspring: Systematic review and meta-analysis of observational studies

There is emerging evidence that events occurring before and shortly after birth may be important in determining the risk of childhood-onset type 1 diabetes mellitus (T1DM). We aimed to summarize and synthesize the associations between maternal body mass index (BMI), maternal diabetes mellitus (DM), and maternal smoking during pregnancy and the risk of childhood-onset T1DM in the offspring by performing a systematic review and meta-analysis of observational studies. A random effects model was used to generate the summary risk estimates. The PubMed and Web of Science databases were searched to identify relevant observational studies. Twenty one observational studies were included in the present meta-analysis. Compared with offspring of mothers with normal weight, offspring of women with overweight or obesity were at an increased risk of developing childhood-onset T1DM (overweight: relative risk [RR] 1.09, 95% confidence interval [CI], 1.03-1.15; obesity: RR 1.25, 95% CI, 1.16-1.34; per 5 kg m^-2 increase in BMI: RR 1.10, 95% CI, 1.06-1.13). No association was found for maternal underweight (RR 0.92, 95% CI, 0.75-1.13). Maternal DM was associated with an increased risk of childhood-onset T1DM (RR 3.26, 95% CI, 2.84-3.74). Regarding the type of maternal DM, the greatest risk of T1DM in the offspring appeared to be conferred by maternal T1DM (RR 4.46, 95% CI, 2.89-6.89), followed by maternal gestational diabetes mellitus (RR 1.66, 95% CI, 1.16-2.36), and lastly by maternal type 2 diabetes mellitus (RR 1.11, 95% CI, 0.69-1.80). Additional analysis of studies comparing maternal versus paternal T1DM within the same population revealed that offspring of fathers with T1DM had a 1.5 times higher risk of developing childhood-onset T1DM than offspring of mothers with T1DM (RR 9.58, 95% CI, 6.33-14.48 vs. RR 6.24, 95% CI, 5.52-7.07). Furthermore, a reduced risk of childhood-onset T1DM was observed in infants born to mothers who smoked during pregnancy compared with infants born to mothers who did not smoke during pregnancy (RR 0.79, 95% CI, 0.71-0.87). In summary, our findings add further evidence that early-life events or environmental factors may play a role in modulating infants' risk of developing T1DM later in life.

Identification of Novel T1D Risk Loci and Their Association With Age and Islet Function at Diagnosis in Autoantibody-Positive T1D Individuals: Based on a Two-Stage Genome-Wide Association Study

OBJECTIVE

Type 1 diabetes (T1D) is a highly heritable disease with much lower incidence but more adult-onset cases in the Chinese population. Although genome-wide association studies (GWAS) have identified >60 T1D loci in Caucasians, less is known in Asians.

RESEARCH DESIGN AND METHODS

We performed the first two-stage GWAS of T1D using 2,596 autoantibody-positive T1D case subjects and 5,082 control subjects in a Chinese Han population and evaluated the associations between the identified T1D risk loci and age and fasting C-peptide levels at T1D diagnosis.

RESULTS

We observed a high genetic correlation between children/adolescents and adult T1D case subjects (r _g = 0.87), as well as subgroups of autoantibody status (r _g ≥ 0.90). We identified four T1D risk loci reaching genome-wide significance in the Chinese Han population, including two novel loci, rs4320356 near BTN3A1 (odds ratio [OR] 1.26, P = 2.70 × 10^-8) and rs3802604 in GATA3 (OR 1.24, P = 2.06 × 10^-8), and two previously reported loci, rs1770 in MHC (OR 4.28, P = 2.25 × 10^-232) and rs705699 in SUOX (OR 1.46, P = 7.48 × 10^-20). Further fine mapping in the MHC region revealed five independent variants, including another novel locus, HLA-C position 275 (omnibus P = 9.78 × 10^-12), specific to the Chinese population. Based on the identified eight variants, we achieved an area under the curve value of 0.86 (95% CI 0.85-0.88). By building a genetic risk score (GRS) with these variants, we observed that the higher GRS were associated with an earlier age of T1D diagnosis (P = 9.08 × 10^-11) and lower fasting C-peptide levels (P = 7.19 × 10^-3) in individuals newly diagnosed with T1D.

CONCLUSIONS

Our results extend current knowledge on genetic contributions to T1D risk. Further investigations in different populations are needed for genetic heterogeneity and subsequent precision medicine.

Prediction and prevention of type 1 diabetes in children

Type 1 diabetes (T1D) is a chronic T-cell mediated autoimmune disease characterized by destruction of beta cells. Although new data have better defined the complex etiology underling the interrelation of genetic and environmental factors in the natural history of T1D, relevant pieces of the puzzle still are missing. Genetic predisposition is mainly associated to some histocompatibility leukocyte antigen (HLA) alleles; however, recent data suggest that new as well as still unknown genes might better define the complex multigenetic risk of the disease. In addition to the genetic effects, the concordance in familial aggregation in T1D indicates a pivotal role of environmental factors in the course of the disease, facilitating autoantibodies production. JDRF has recently proposed a new early stage of T1D according to which the detection of two or more autoantibodies in the blood, might describe those children at increased risk of developing T1D during the following years. In contrast to the improvements reached by prediction models, to date primary, secondary and tertiary prevention have still failed to achieve a safe and efficacious intervention strategies. Anyway, the most recent progresses in this field pave the way for future studies, with the aim of preventing T1D in children.

Chaperones may cause the focus of diabetes autoimmunity on distinct (pro)insulin peptides

It is still an enigma why T cell autoreactivity in type 1 diabetes targets few beta cell antigens only. Among these, one primary autoantigen is pro(insulin). Autoimmune T cells preferentially recognise three epitopes on the proinsulin molecule, of which the peptide region B:11-23 is the dominant one. Interestingly, the three regions superimpose with binding sites of the chaperone hsp70, the region B:11-23 being the strongest binding one. Absence of an intact core region B:15-17 prevents autoimmune diabetes in NOD as well as binding of hsp70. A role of hsp70 in selecting autoimmune epitopes is supported by the ability of this and other chaperones to deliver bound peptides to MHC class I and II molecules for efficient antigen presentation. Binding of hsp70 to receptors on antigen presenting cells such as TLR4 results in costimulatory signals for T cell activation. Strongest effects are seen for the mixture of hsp70 with the peptide B:11-23. Thus, hsp70 may assist in proinsulin epitope selection and efficient presentation to autoreactive T cells. The concept of chaperone guided immune reactivity may also apply to other autoimmune diseases.

The role of proteomics in assessing beta-cell dysfunction and death in type 1 diabetes

Introduction: Type 1 diabetes (T1D) is characterized by autoimmune-induced dysfunction and destruction of the pancreatic beta cells. Unfortunately, this process is poorly understood, and the current best treatment for type 1 diabetes is the administration of exogenous insulin. To better understand these mechanisms and to develop new therapies, there is an urgent need for biomarkers that can reliably predict disease stage. Areas covered: Mass spectrometry (MS)-based proteomics and complementary techniques play an important role in understanding the autoimmune response, inflammation and beta-cell death. MS is also a leading technology for the identification of biomarkers. This, and the technical difficulties and new technologies that provide opportunities to characterize small amounts of sample in great depth and to analyze large sample cohorts will be discussed in this review. Expert opinion: Understanding disease mechanisms and the discovery of disease-associated biomarkers are highly interconnected goals. Ideal biomarkers would be molecules specific to the different stages of the disease process that are released from beta cells to the bloodstream. However, such molecules are likely to be present in trace amounts in the blood due to the small number of pancreatic beta cells in the human body and the heterogeneity of the target organ and disease process.

Altered N-glycosylation profiles as potential biomarkers and drug targets in diabetes

N-glycosylation is a ubiquitous protein modification, and N-glycosylation profiles are emerging as both biomarkers and functional effectors in various types of diabetes. Genome-wide association studies identified glycosyltransferase genes as candidate causal genes for type 1 and type 2 diabetes. Studies focused on N-glycosylation changes in type 2 diabetes demonstrated that patients can be distinguished from healthy controls based on N-glycome composition. In addition, individuals at an increased risk of future disease development could be identified based on N-glycome profiles. Moreover, accumulating evidence indicates that N-glycans have a major role in preventing the impairment of glucose-stimulated insulin secretion by maintaining the glucose transporter in proper orientation, indicating that interindividual variation in protein N-glycosylation might be a novel risk factor contributing to diabetes development. Defective N-glycosylation of T cells has been implicated in type 1 diabetes pathogenesis. Furthermore, studies of N-glycan alterations have successfully been used to identify individuals with rare types of diabetes (such as the HNF1A-MODY), and also to evaluate functional significance of novel diabetes-associated mutations. In conclusion, both N-glycans and glycosyltransferases emerge as potential therapeutic targets in diabetes.

Loss of MafA and MafB expression promotes islet inflammation

Maf transcription factors are critical regulators of beta-cell function. We have previously shown that reduced MafA expression in human and mouse islets is associated with a pro-inflammatory gene signature. Here, we investigate if the loss of Maf transcription factors induced autoimmune processes in the pancreas. Transcriptomics analysis showed expression of pro-inflammatory as well as immune cell marker genes. However, clusters of CD4+ T and B220+ B cells were associated primarily with adult MafA^−/−MafB^+/−, but not MafA^−/− islets. MafA expression was detected in the thymus, lymph nodes and bone marrow suggesting a novel role of MafA in regulating immune-cell function. Analysis of pancreatic lymph node cells showed activation of CD4+ T cells, but lack of CD8+ T cell activation which also coincided with an enrichment of naïve CD8+ T cells. Further analysis of T cell marker genes revealed a reduction of T cell receptor signaling gene expression in CD8, but not in CD4+ T cells, which was accompanied with a defect in early T cell receptor signaling in mutant CD8+ T cells. These results suggest that loss of MafA impairs both beta- and T cell function affecting the balance of peripheral immune responses against islet autoantigens, resulting in local inflammation in pancreatic islets.

[Improving the management of children with type 1 diabetes and their families: What role for the advanced practice nurse, coordinator of complex care pathways? A qualitative, exploratory study using semi-directed interviews]

BACKGROUND

Type 1 diabetes in children in Switzerland is becoming increasingly prevalent. The coordination of care seems to be a determining element and is essential for effective and efficient care.

OBJECTIVE

Identify the difficulties and the levers of coordination faced by healthcare workers and families during the discovery of type 1 diabetes in children aged from birth to fifteen.

METHOD

Qualitative analysis using semi-directed interviews.

RESULTS

Three families and five healthcare workers participated in the study. Confirmation of the diagnosis was received badly and was a shock for the families. Nurses specializing in pediatric diabetes are recognized for being experts in diabetes care and education. Non-specialist nurses consider diabetes care to be stressful and complex. Collaboration between units is described as compartmentalized. ICT tools are not shared between units. Psychological support is considered to be unsatisfactory by the families.

DISCUSSION

Interdisciplinary nurses need to work together and with a structured coordination of care.

Lower Incidence Rate of Type 1 Diabetes after Receipt of the Rotavirus Vaccine in the United States, 2001-2017

We evaluated whether rotavirus vaccination is associated with the incidence of type 1 diabetes among children. We designed a cohort study of 1,474,535 infants in the United States from 2001–2017, using data from a nationwide health insurer. There was a 33% reduction in the risk of type 1 diabetes with completion of the rotavirus vaccine series compared to the unvaccinated (95% CI: 17%, 46%). Completion of the pentavalent vaccine series was associated with 37% lower risk of type 1 diabetes (95% CI: 22%, 50%). Partial vaccination (incompletion of the series) was not associated with the incidence of type 1 diabetes. There was a 31% reduction in hospitalizations in the 60-day period after vaccination (95% CI: 27%, 35%) compared to unvaccinated children. Overall, there was a 3.4% decrease in incidence annually in children ages 0–4 in the United States from 2006–2017 which coincides with the vaccine introduction in 2006. We conclude that rotavirus vaccination is associated with a reduced incidence of type 1 diabetes. Rotavirus vaccination may be the first practical measure that could play a role in the prevention of this disease.

The association between rs1893217, rs478582 in PTPN2 and T1D risk with different diagnosed age, and related clinical characteristics in Chinese Han population

OBJECTIVE

To investigate the association between polymorphisms in PTPN2 (rs1893217 and rs478582) and type 1 diabetes (T1D) risk with different diagnosed age, as well as related clinical characteristics in Chinese Han population.

METHODS

A total of 2270 Chinese Han individuals (1023 T1D patients and 1247 healthy controls) were genotyped for rs1893217 and rs478582. And 306 newly diagnosed T1D patients were measured for C-peptide levels based on a standard mixed-meal tolerance test. In addition, 40 healthy controls were analyzed for different T cell subsets by multi-color flow cytometry.

RESULTS

Neither rs1893217 nor rs478582 showed any association with T1D risk under an additive model. Stratified analysis for T1D diagnosed age revealed that rs1893217, but not rs478582, was significantly associated with T1D patients diagnosed age ≤18 (OR =0.80, 95% CI: 0.67-0.97, p = 0.02). For those diagnosed age >18, neither of them showed any association. We also found that rs1893217 had a higher positive rate of ZnT8A (CC vs. TT carrier, OR = 2.07, 95% CI: 1.07-4.03, p = 0.026) and IA-2A (CT vs. TT carrier, OR = 1.36, 95% CI: 1.02-1.80, p = 0.038). Furthermore, for rs478582, compared with TT, healthy individuals carrying CC/CT carriers had significantly lower frequency and Helios expression of naive Treg subsets (p = 0.049 and 0.048 respectively), but not secreting or activating Treg subsets. In addition, we did not find any association between these two polymorphisms and residual β-cell function in newly diagnosed T1D patients.

CONCLUSIONS

Our results suggest that rs1893217 may increase the risk of early-onset T1D and affect humoral immunity, while rs478582 may affect Treg subsets.

Maternal and Early Life Iron Intake and Risk of Childhood Type 1 Diabetes: A Danish Case-Cohort Study

Background: Iron overload has been associated with diabetes. Studies on iron exposure during pregnancy and in early life and risk of childhood type 1 diabetes (T1D) are sparse. We investigated whether iron supplementation during pregnancy and early in life were associated with risk of childhood T1D. Methods: In a case-cohort design, we identified up to 257 children with T1D (prevalence 0.37%) from the Danish National Birth Cohort through linkage with the Danish Childhood Diabetes Register. The primary exposure was maternal pure iron supplementation (yes/no) during pregnancy as reported in interview two at 30 weeks of gestation (n = 68,497 with iron supplement data). We estimated hazard ratios (HRs) using weighted Cox regression adjusting for multiple confounders. We also examined if offspring supplementation during the first 18 months of life was associated with later risk of T1D. Results: Maternal iron supplementation was not associated with later risk of T1D in the offspring HR 1.05 (95% CI: 0.76–1.45). Offspring intake of iron droplets during the first 18 months of life was inversely associated with risk of T1D HR 0.74 (95% CI: 0.55–1.00) (p_trend = 0.03). Conclusions: Our large-scale prospective study demonstrated no harmful effects of iron supplementation during pregnancy and in early life in regard to later risk of childhood T1D in the offspring.

Probiotics and Prebiotics for the Amelioration of Type 1 Diabetes: Present and Future Perspectives

Type 1-diabetes (T1D) is an autoimmune disease characterized by immune-mediated destruction of pancreatic beta (β)-cells. Genetic and environmental interactions play an important role in immune system malfunction by priming an aggressive adaptive immune response against β-cells. The microbes inhabiting the human intestine closely interact with the enteric mucosal immune system. Gut microbiota colonization and immune system maturation occur in parallel during early years of life; hence, perturbations in the gut microbiota can impair the functions of immune cells and vice-versa. Abnormal gut microbiota perturbations (dysbiosis) are often detected in T1D subjects, particularly those diagnosed as multiple-autoantibody-positive as a result of an aggressive and adverse immunoresponse. The pathogenesis of T1D involves activation of self-reactive T-cells, resulting in the destruction of β-cells by CD8⁺ T-lymphocytes. It is also becoming clear that gut microbes interact closely with T-cells. The amelioration of gut dysbiosis using specific probiotics and prebiotics has been found to be associated with decline in the autoimmune response (with diminished inflammation) and gut integrity (through increased expression of tight-junction proteins in the intestinal epithelium). This review discusses the potential interactions between gut microbiota and immune mechanisms that are involved in the progression of T1D and contemplates the potential effects and prospects of gut microbiota modulators, including probiotic and prebiotic interventions, in the amelioration of T1D pathology, in both human and animal models.

DEXI, a candidate gene for type 1 diabetes, modulates rat and human pancreatic beta cell inflammation via regulation of the type I IFN/STAT signalling pathway

AIMS/HYPOTHESIS

The initial stages of type 1 diabetes are characterised by an aberrant islet inflammation that is in part regulated by the interaction between type 1 diabetes susceptibility genes and environmental factors. Chromosome 16p13 is associated with type 1 diabetes and CLEC16A is thought to be the aetiological gene in the region. Recent gene expression analysis has, however, indicated that SNPs in CLEC16A modulate the expression of a neighbouring gene with unknown function named DEXI, encoding dexamethasone-induced protein (DEXI). We therefore evaluated the role of DEXI in beta cell responses to 'danger signals' and determined the mechanisms involved.

METHODS

Functional studies based on silencing or overexpression of DEXI were performed in rat and human pancreatic beta cells. Beta cell inflammation and apoptosis, driven by a synthetic viral double-stranded RNA, were evaluated by real-time PCR, western blotting and luciferase assays.

RESULTS

DEXI-silenced beta cells exposed to a synthetic double-stranded RNA (polyinosinic:polycytidylic acid [PIC], a by-product of viral replication) showed reduced activation of signal transducer and activator of transcription (STAT) 1 and lower production of proinflammatory chemokines that was preceded by a reduction in IFNβ levels. Exposure to PIC increased chromatin-bound DEXI and IFNβ promoter activity. This effect on IFNβ promoter was inhibited in DEXI-silenced beta cells, suggesting that DEXI is implicated in the regulation of IFNβ transcription. In a mirror image of knockdown experiments, DEXI overexpression led to increased levels of STAT1 and proinflammatory chemokines.

CONCLUSIONS/INTERPRETATION

These observations support DEXI as the aetiological gene in the type 1 diabetes-associated 16p13 genomic region, and provide the first indication of a link between this candidate gene and the regulation of local antiviral immune responses in beta cells. Moreover, our results provide initial information on the function of DEXI.

Development and Standardization of an Improved Type 1 Diabetes Genetic Risk Score for Use in Newborn Screening and Incident Diagnosis

OBJECTIVE

Previously generated genetic risk scores (GRSs) for type 1 diabetes (T1D) have not captured all known information at non-HLA loci or, particularly, at HLA risk loci. We aimed to more completely incorporate HLA alleles, their interactions, and recently discovered non-HLA loci into an improved T1D GRS (termed the "T1D GRS2") to better discriminate diabetes subtypes and to predict T1D in newborn screening studies.

RESEARCH DESIGN AND METHODS

In 6,481 case and 9,247 control subjects from the Type 1 Diabetes Genetics Consortium, we analyzed variants associated with T1D both in the HLA region and across the genome. We modeled interactions between variants marking strongly associated HLA haplotypes and generated odds ratios to create the improved GRS, the T1D GRS2. We validated our findings in UK Biobank. We assessed the impact of the T1D GRS2 in newborn screening and diabetes classification and sought to provide a framework for comparison with previous scores.

RESULTS

The T1D GRS2 used 67 single nucleotide polymorphisms (SNPs) and accounted for interactions between 18 HLA DR-DQ haplotype combinations. The T1D GRS2 was highly discriminative for all T1D (area under the curve [AUC] 0.92; P < 0.0001 vs. older scores) and even more discriminative for early-onset T1D (AUC 0.96). In simulated newborn screening, the T1D GRS2 was nearly twice as efficient as HLA genotyping alone and 50% better than current genetic scores in general population T1D prediction.

CONCLUSIONS

An improved T1D GRS, the T1D GRS2, is highly useful for classifying adult incident diabetes type and improving newborn screening. Given the cost-effectiveness of SNP genotyping, this approach has great clinical and research potential in T1D.

Genotypes of HLA, TCF7L2, and FTO as potential modifiers of the association between sweetened beverage consumption and risk of LADA and type 2 diabetes

Purpose

Sweetened beverage consumption is associated with type 2 diabetes (T2D) and LADA. We investigated to what extent this association is mediated by BMI and whether it is modified by genotypes of HLA, TCF7L2 rs7903146, or FTO rs9939609.

Methods

Swedish case–control data including incident cases of LADA (n = 386) and T2D (n = 1253) with matched population-based controls (n = 1545) was used. We estimated adjusted ORs of diabetes (95% CI) in relation to sweetened beverage intake (per daily 200 mL serving) and genotypes. The impact of BMI was estimated using causal mediation methodology. Associations with HOMA-IR and HOMA-B were explored through linear regression.

Results

Sweetened beverage intake was associated with increased risk of LADA (OR 1.15, 95% CI 1.03–1.29) and T2D (OR 1.21, 1.11–1.32). BMI was estimated to mediate 17% (LADA) and 56% (T2D) of the total risk. LADA was associated with risk variants of HLA (3.44, 2.63–4.50) and TCF7L2 (1.27, 1.00–1.61) but not FTO. Only among non-carriers of high-risk HLA genotypes was sweetened beverage intake associated with risk of LADA (OR 1.32, 1.06–1.56) and HOMA-IR (beta = 0.162, p = 0.0047). T2D was associated with TCF7L2 and FTO but not HLA, and the risk conferred by sweetened beverages appeared modified by FTO (OR 1.45, 95% CI 1.21–1.73 in non-carriers).

Conclusions

Our findings suggest that sweetened beverages are associated with LADA and T2D partly through mediation by excess weight, but possibly also through other mechanisms including adverse effects on insulin sensitivity. These effects seem more pronounced in individuals without genetic susceptibility.

Electronic supplementary material

The online version of this article (10.1007/s00394-019-01893-x) contains supplementary material, which is available to authorized users.

Perceptions of patients regarding diabetes-related health communication strategies in the Free State, South Africa

BACKGROUND

This study researched the perceptions of patients diagnosed with diabetes concerning diabetes-related health communication strategies in the Free State province in South Africa. The prolongation and quality of life of patients diagnosed with diabetes are affected by lifestyle choices. An enabler of risk reduction is health communication which informs, influences and motivates individuals to adopted health-focused lifestyles.

AIM

This study sought to describe the perceptions of patients regarding diabetes-related health communication strategies in the Free State, South Africa.

SETTING

This study was carried out in primary health care centres and community health care centres within the Free State province in South Africa.

METHODS

A qualitative, descriptive and exploratory research design was used in this study. Thirty-four patients diagnosed with type two diabetes for at least a year were purposively included in this study. Semi-structured interviews in Afrikaans, English, Sotho and Xhosa were conducted. Data analysis was through inductive reasoning and thematic analysis.

RESULTS

The majority of the respondents were older women having been diagnosed with diabetes for more than 5 years, with at least primary school education and of diverse South African ethnicities. The main prompting questions operationalised the term 'perception', probing their feelings, experiences and knowledge of health-related communication strategies as presented by a variety of information sources. After recording interviews, data were analysed according to themes, categories and sub-categories.

CONCLUSIONS

The study highlights factors that encourage patients to seek help and foster attitudes of compliance. Practical problems regarding the management of diabetes are underlined. The role of family, as well as the patient-caregiver relationship, in the acceptance and management of the disease is revealed. Societal perception of male symptomology is shown. The study offers information to stakeholders and health care workers for continued successful management of diabetes in communities.

Polymorphisms in NLRP1 Gene Are Associated with Type 1 Diabetes

OBJECTIVE

The aim of this study was to clarify the association of two single-nucleotide polymorphisms (SNPs) (rs11651270 and rs2670660) in the NLRP1 (NLR family pyrin domain containing 1) gene with type 1 diabetes (T1D) in the Chinese Han population. We hypothesize that mutations in the NLRP1 gene may affect the susceptibility to T1D.

MATERIALS AND METHODS

A case control study was designed, and participants fulfilling the diagnostic criteria of classical T1D as well as nondiabetic controls were enrolled in the study. The polymorphisms rs11651270 and rs2670660 were genotyped by polymerase chain reaction (PCR) and Sanger sequencing. Chi-squared test and logistic regression analysis were performed to compare the distributions of the allele and genotype between cases and controls. Kruskal-Wallis one-way ANOVA was used to compare the characteristics of different genotypes in participants with T1D.

RESULTS

A total of 510 participants with classical T1D as well as 531 nondiabetic controls were enrolled in the study. The two groups were matched in sex (p = 0.418). The age (p < 0.001) and BMI (p < 0.001) were significantly lower in cases compared to controls. Significantly higher values were observed for fasting plasma glucose (FPG) (p < 0.001) and 2 h postprandial plasma glucose (PPG) (p < 0.001) in individuals with T1D. Regarding the allelic model, the minor allele C of rs11651270 was significantly associated with lower risk of T1D compared with the T allele (OR = 0.714, 95% CI = 0.579-0.882). Both rs11651270 and rs2670660 polymorphisms were associated with T1D in the Chinese Han population under a dominant model (OR = 0.648, 95% CI = 0.503-0.834 and OR = 0.716, 95% CI = 0.549-0.934, respectively) and an overdominant model (OR = 0.663, 95% CI = 0.511-0.860 and OR = 0.711, 95% CI = 0.541-0.935, respectively). Additionally, the polymorphism rs11651270 was also related to T1D in an additive model (OR = 0.719, 95% CI = 0.583-0.887). Most importantly, when we analyzed the clinical characteristics of T1D individuals with different genotypes, we found that the age of onset with the TT genotype at rs11651270 was younger than those with the other two genotypes (p = 0.001).

CONCLUSIONS

SNPs in the NLRP1 gene were associated with T1D, as well as the age of onset in the Chinese Han T1D individuals. Our study indicated that the NLRP1 gene might play a pivotal role in the etiopathogenesis of T1D and could be applied to genetic screening of T1D in the Chinese Han population.

Diabetes causal attributions among affected and unaffected individuals

OBJECTIVE

The present study aims to describe and compare causal attributions for type 1 diabetes (T1D) and type 2 diabetes (T2D) among affected and unaffected individuals and to investigate the relationships among attributions, attitudes, and beliefs.

RESEARCH DESIGN AND METHODS

Adults with no diabetes (N=458), T1D (N=192), or T2D (N=207) completed an online survey. Measures assessed diabetes conceptual knowledge, causal attributions for T1D and T2D, perceived control over diabetes onset, and favorability judgements of individuals affected by each type.

RESULTS

Results indicate general agreement on causal attributions for T1D and T2D among all respondent groups, with some divergences by disease status. All respondents attributed both T1D and T2D to genetics, and genetic attributions were positively associated with favorability judgements of individuals with T2D, but not those with T1D.

CONCLUSIONS

This report sets the stage for investigations into how and why attributions for T1D and T2D differ and the implications of these differences including stigmatization of individuals with diabetes and diabetes-related self-concept. Additionally, this work can inform efforts towards clinical and public health education to prevent and optimize treatment of T1D and T2D.

Incidence and trend of type 1 diabetes and the underlying environmental determinants

A wealth of epidemiological studies concerning the distribution of type 1 diabetes (T1D) around the world have pointed to the appreciable variation in the incidence of T1D among disparate age groups, ethnicities, and geographical locations. On the whole, the incidence of childhood T1D has been on the rise, and a plausible inverse relationship between the initial incidence rate and the following annual increase in incidence has been raised. Countries that used to exhibit lower incidences tend to have steep annual increase whereas those with already-established high incidences are more likely to show a modest increase or even stabilization in T1D incidence. Environmental agents considered responsible for the current evolving pattern of T1D incidence will be detailed, mainly including the increasing prevalence of childhood obesity, viral infections in a chronic manner, maternal-child interaction such as breastfeeding, and latitude-ultraviolet B-vitamin D pathway. Certain rationale has been put forward in an attempt to explain the potential association between environmental agents and development of T1D. For instance, accelerator hypothesis regards insulin resistance as the promoter of earlier disease onset in obese children whereas the negative correlation of microbial infections in background populations with incidence of T1D represents the basic component of the hygiene hypothesis. Further investigations are still warranted to verify these theories across multiple ethnic groups and to identify additional contributors to the variation in T1D incidence.

Immunomodulatory Effect of Vitamin D and Its Potential Role in the Prevention and Treatment of Type 1 Diabetes Mellitus-A Narrative Review

Type 1 diabetes mellitus is a chronic autoimmune disease associated with degeneration of pancreatic β-cells that results in an inability to produce insulin and the need for exogenous insulin administration. It is a significant global health problem as the incidence of this disorder is increasing worldwide. The causes are still poorly understood, although it certainly has genetic and environmental origins. Vitamin D formed profusely in the skin upon exposure to sunlight, as well as from dietary sources, exhibits an immunomodulatory effect based on gene transcription control. Indeed, vitamin D can downregulate mechanisms connected with adaptive immunity, induce immunological tolerance and decrease auto-aggression-related inflammation. These properties provide the basis for a preventive and therapeutic role of vitamin D. As many studies have demonstrated, appropriate supplementation with vitamin D reduces the risk of autoimmune diseases, including type 1 diabetes mellitus, and alleviates disease symptoms in patients. The aim of this narrative review is to present the molecular mechanisms for the vitamin D immunomodulatory effect as well as review human clinical studies on the use of vitamin D as adjuvant therapy in type 1 diabetes mellitus.

The prognostic role of depression as a predictor of chronic somatic diseases manifestation

The negative impact of depression on the course and outcome of somatic disorders is well-known and has a solid theoretical basis. The analyses of prospective studies confirm the role of depression as an independent and significant risk factor for widespread chronic somatic disorders including such severe and life-threatening conditions as cardiovascular diseases, diabetes and oncological pathology. The majority of somatic disorders and depression are the part of the big class of hereditary diseases with multifactorial character and polygenic nature. It is likely, that the genetic risk diversity of these diseases in population is close. There is also a high probability of genetic risks levels overlap (or of common «cluster») of two or more diseases in one individual, with one disorder being major depression. In that case such diseases could be considered «genetically comorbid» and manifestation of one disease could alter the risks of other. Precise and informative diagnostic tools could detect subsyndromal depression that could be the prognostic sign of the high risk and rapid manifestation of somatic diseases. Thus, patients with depressive disorder could be considered as a group with high risks of diverse range of somatic pathology. The coalescence of fundamental biomedical scientists and internists (psychiatrists and other physicians) could lead to the elaboration of specific complex preventative measures including social ones.

High prevalence of humoral autoimmunity in first-degree relatives of Mexican type 1 diabetes patients

AIMS

To assess the prevalence of autoantibodies (Aab) to insulin (IAA), glutamic acid decarboxylase 65 (GADA) and insulinoma antigen 2 (IA-2A), as well as human leukocyte antigen (HLA) class II alleles, in first degree relatives (FDR) of Mexican patients with type 1 diabetes (T1D), and to explore whether these parameters mirror the low incidence of T1D in the Mexican population.

METHODS

Aab titers were determined by ELISA in 425 FDR, 234 siblings, 40 offspring and 151 parents of 197 patients with T1D. Typing of HLA-DR and -DQ alleles was performed in 41 Aab-positive FDR using polymerase chain reaction with allele-specific oligotyping.

RESULTS

Seventy FDR (16.47%) tested positive for Aab. The siblings (19.2%) and the offspring (25%) had significantly higher prevalence of Aab than the parents (9.9%). GADA was the most frequent Aab. Almost half of the Aab-positive FDR had two different Aab (45.7%), and none tested positive for three Aab. The highest prevalence of Aab was found among women in the 15-29 years age group. Moreover, the positivity for two Aab was significantly more frequent among females. A considerable number of FDR (48.8%) carried the susceptible HLA-DR3, -DR4, -DQB1*0201 or -DQB1*0302 alleles, but almost none had the high risk genotype HLA-DR3/DR4.

CONCLUSIONS

FDR of Mexican T1D patients have high prevalence of islet Aab, comparable to countries with the highest incidence of T1D. However, Aab positivity does not seem to be associated with HLA risk genotypes, which may have an impact on the low incidence of T1D in Mexico.

Influence of Disease Duration on Circulating Levels of miRNAs in Children and Adolescents with New Onset Type 1 Diabetes

Circulating microRNAs (miRNAs) have been implicated in several pathologies including type 1 diabetes. In the present study, we aimed to identify circulating miRNAs affected by disease duration in children with recent onset type 1 diabetes. Forty children and adolescents from the Danish Remission Phase Cohort were followed with blood samples drawn at 1, 3, 6, 12, and 60 months after diagnosis. Pancreatic autoantibodies were measured at each visit. Cytokines were measured only the first year. miRNA expression profiling was performed by RT-qPCR. The effect of disease duration was analyzed by mixed models for repeated measurements adjusted for sex and age. Eight miRNAs (hsa-miR-10b-5p, hsa-miR-17-5p, hsa-miR-30e-5p, hsa-miR-93-5p, hsa-miR-99a-5p, hsa-miR-125b-5p, hsa-miR-423-3p, and hsa-miR-497-5p) were found to significantly change in expression (adjusted p-value < 0.05) with disease progression. Three pancreatic autoantibodies, ICA, IA-2A, and GAD65A, and four cytokines, IL-4, IL-10, IL-21, and IL-22, were associated with the miRNAs at different time points. Pathway analysis revealed associations with various immune-mediated signaling pathways. Eight miRNAs that were involved in immunological pathways changed expression levels during the first five years after diagnosis and were associated with variations in cytokine and pancreatic antibodies, suggesting a possible effect on the immunological processes in the early phase of the disease.

Possible Prevention of Diabetes with a Gluten-Free Diet

Gluten seems a potentially important determinant in type 1 diabetes (T1D) and type 2 diabetes (T2D). Intake of gluten, a major component of wheat, rye, and barley, affects the microbiota and increases the intestinal permeability. Moreover, studies have demonstrated that gluten peptides, after crossing the intestinal barrier, lead to a more inflammatory milieu. Gluten peptides enter the pancreas where they affect the morphology and might induce beta-cell stress by enhancing glucose- and palmitate-stimulated insulin secretion. Interestingly, animal studies and a human study have demonstrated that a gluten-free (GF) diet during pregnancy reduces the risk of T1D. Evidence regarding the role of a GF diet in T2D is less clear. Some studies have linked intake of a GF diet to reduced obesity and T2D and suggested a role in reducing leptin- and insulin-resistance and increasing beta-cell volume. The current knowledge indicates that gluten, among many environmental factors, may be an aetiopathogenic factors for development of T1D and T2D. However, human intervention trials are needed to confirm this and the proposed mechanisms.

Innate immune activity as a predictor of persistent insulin secretion and association with responsiveness to CTLA4-Ig treatment in recent-onset type 1 diabetes

AIMS/HYPOTHESIS

The study aimed to determine whether discrete subtypes of type 1 diabetes exist, based on immunoregulatory profiles at clinical onset, as this has significant implications for disease treatment and prevention as well as the design and analysis of clinical trials.

METHODS

Using a plasma-based transcriptional bioassay and a gene-ontology-based scoring algorithm, we examined local participants from the Children's Hospital of Wisconsin and conducted an ancillary analysis of TrialNet CTLA4-Ig trial (TN-09) participants.

RESULTS

The inflammatory/regulatory balance measured during the post-onset period was highly variable. Notably, a significant inverse relationship was identified between baseline innate inflammatory activity and stimulated C-peptide AUC measured at 3, 6, 12, 18 and 24 months post onset among placebo-treated individuals (p ≤ 0.015). Further, duration of persistent insulin secretion was negatively related to baseline inflammation (p ≤ 0.012) and positively associated with baseline abundance of circulating activated regulatory T cells (CD4⁺/CD45RA^-/FOXP3^high; p = 0.016). Based on these findings, data from participants treated with CTLA4-Ig were stratified by inflammatory activity at onset; in this way, we identified pathways and transcripts consistent with inhibition of T cell activation and enhanced immunoregulation. Variance among baseline plasma-induced signatures of TN-09 participants was further examined with weighted gene co-expression network analysis and related to clinical metrics. Four age-independent subgroups were identified that differed in terms of baseline innate inflammatory/regulatory bias, rate of C-peptide decline and response to CTLA4-Ig treatment.

CONCLUSIONS/INTERPRETATION

These data support the existence of multiple type 1 diabetes subtypes characterised by varying levels of baseline innate inflammation that are associated with the rate of C-peptide decline.

DATA AVAILABILITY

Gene expression data files are publicly available through the National Center for Biotechnology Information Gene Expression Omnibus (accession number GSE102234).

A systematic review of non-genetic predictors and genetic factors of glycated haemoglobin in type 1 diabetes one year after diagnosis

Type 1 diabetes (T1D) results from autoimmune destruction of the pancreatic βcells. Although all T1D patients require daily administration of exogenous insulin, their insulin requirement to achieve good glycaemic control may vary significantly. Glycated haemoglobin (HbA1c) level represents a stable indicator of glycaemic control and is a reliable predictor of long-term complications of T1D. The purpose of this article is to systematically review the role of non-genetic predictors and genetic factors of HbA1c level in T1D patients after the first year of T1D, to exclude the honeymoon period. A total of 1974 articles published since January 2011 were identified and 78 were finally included in the analysis of non-genetic predictors. For genetic factors, a total of 277 articles were identified and 14 were included. The most significantly associated factors with HbA1c level are demographic (age, ethnicity, and socioeconomic status), personal (family characteristics, parental care, psychological traits...) and features related to T1D (duration of T1D, adherence to treatment …). Only a few studies have searched for genetic factors influencing HbA1c level, most of which focused on candidate genes using classical genetic statistical methods, with generally limited power and incomplete adjustment for confounding factors and multiple testing. Our review shows the complexity of explaining HbA1c level variations, which involves numerous correlated predictors. Overall, our review underlines the lack of studies investigating jointly genetic and non-genetic factors and their interactions to better understand factors influencing glycaemic control for T1D patients.

Pet exposure in the family during pregnancy and risk for type 1 diabetes-The prospective ABIS study

BACKGROUND

The autoimmune process later leading to type 1 diabetes (T1D) seems to start very early in life. Different viruses have been suspected to contribute to the development of T1D, some already during pregnancy. As viruses may be hosted by animals and from them transferred to humans we decided to investigate if exposure to pets during pregnancy is related to later development of T1D.

METHODS

ABIS (All Babies in Southeast Sweden)-is a prospective population-based cohort study of unselected children born in southeast Sweden between Oct first 1997 to Oct first 1999. Parents of 16 384 children answered a questionnaire within 3 days after birth including information about exposure to different pets. The ABIS registry has been connected to the National Registry of diagnosis and also the national Registry of Drug prescriptions so we know that 137 children have got T1D, and they were compared with the non-diabetic population.

RESULTS

During pregnancy, 45.5% of the mothers had pet animals at home. Most common were cats (25.0%) and dogs (18.7%). Neither exposure to dogs (OR = 1.27, P = 0.23) or cats (OR = 0.81, P = 0.31) were associated to later T1D risks. However, exposure to hamsters increased the T1D risk (OR 4.21, P = 0.0007). In a multiple regression this association remained (P = 0.005) when adjusted for other possible risk factors.

CONCLUSIONS

Exposure to hamster during pregnancy seems to increase the risk of T1D in the child. One possibility could be infection by virus hosted by the pet.

Abnormal T Cell Frequencies, Including Cytomegalovirus-Associated Expansions, Distinguish Seroconverted Subjects at Risk for Type 1 Diabetes

We analyzed T cell subsets from cryopreserved PBMC obtained from the TrialNet Pathway to Prevention archives. We compared subjects who had previously seroconverted for one or more autoantibodies with non-seroconverted, autoantibody negative individuals. We observed a reduced frequency of MAIT cells among seroconverted subjects. Seroconverted subjects also possessed decreased frequencies of CCR4-expressing CD4 T cells, including a regulatory-like subset. Interestingly, we found an elevation of CD57+, CD28–, CD127–, CD27– CD8 T cells (SLEC) among seroconverted subjects that was most pronounced among those that progressed to disease. The frequency of these SLEC was strongly correlated with CMV IgG abundance among seroconverted subjects, associated with IA-2 levels, and most elevated among CMV+ seroconverted subjects who progressed to disease. Combined, our data indicate discrete, yet profound T cell alterations are associated with islet autoimmunity among at-risk subjects.

Epigenetics Variation and Pathogenesis in Diabetes

PURPOSE OF REVIEW

Great strides have recently been made in elucidating the role of genetic sequence variation in diabetes pathogenesis. Increasingly, studies are focusing on other factors that may contribute to the pathogenesis of diabetes, such as epigenetics, a term "traditionally" encompassing changes to the DNA that do not alter sequence and are heritable (primary methylation and histone modification) but often expanded to include microRNAs. This review summarizes latest findings on the role of epigenetics in diabetes pathogenesis.

RECENT FINDINGS

Recent studies illustrate roles for methylation changes, histone modification, imprinting, and microRNAs across several diabetes types and complications. Notably, methylation changes in the human leukocyte antigen (HLA) region have been found to precede the development of type 1 diabetes. In type 2 diabetes, lifestyle factors appear to interact with epigenetic mechanisms in pathogenesis. Emerging technologies have allowed increasingly comprehensive descriptive analysis of the role of epigenetic mechanisms in diabetes pathogenesis which have yielded meaningful insights into effects on expression of relevant genes. These findings have the potential to inform future development of predictive testing to enable primary prevention and further work to uncover the complex pathogenesis of diabetes.

Obesity in Type 1 Diabetes: Pathophysiology, Clinical Impact, and Mechanisms

There has been an alarming increase in the prevalence of obesity in people with type 1 diabetes in recent years. Although obesity has long been recognized as a major risk factor for the development of type 2 diabetes and a catalyst for complications, much less is known about the role of obesity in the initiation and pathogenesis of type 1 diabetes. Emerging evidence suggests that obesity contributes to insulin resistance, dyslipidemia, and cardiometabolic complications in type 1 diabetes. Unique therapeutic strategies may be required to address these comorbidities within the context of intensive insulin therapy, which promotes weight gain. There is an urgent need for clinical guidelines for the prevention and management of obesity in type 1 diabetes. The development of these recommendations will require a transdisciplinary research strategy addressing metabolism, molecular mechanisms, lifestyle, neuropsychology, and novel therapeutics. In this review, the prevalence, clinical impact, energy balance physiology, and potential mechanisms of obesity in type 1 diabetes are described, with a special focus on the substantial gaps in knowledge in this field. Our goal is to provide a framework for the evidence base needed to develop type 1 diabetes-specific weight management recommendations that account for the competing outcomes of glycemic control and weight management.

The human gut microbiome in early-onset type 1 diabetes from the TEDDY study

Type 1 diabetes (T1D) is an autoimmune disease that targets pancreatic islet beta cells and incorporates genetic and environmental factors1, including complex genetic elements2, patient exposures3 and the gut microbiome4. Viral infections5 and broader gut dysbioses6 have been identified as potential causes or contributing factors; however, human studies have not yet identified microbial compositional or functional triggers that are predictive of islet autoimmunity or T1D. Here we analyse 10,913 metagenomes in stool samples from 783 mostly white, non-Hispanic children. The samples were collected monthly from three months of age until the clinical end point (islet autoimmunity or T1D) in the The Environmental Determinants of Diabetes in the Young (TEDDY) study, to characterize the natural history of the early gut microbiome in connection to islet autoimmunity, T1D diagnosis, and other common early life events such as antibiotic treatments and probiotics. The microbiomes of control children contained more genes that were related to fermentation and the biosynthesis of short-chain fatty acids, but these were not consistently associated with particular taxa across geographically diverse clinical centres, suggesting that microbial factors associated with T1D are taxonomically diffuse but functionally more coherent. When we investigated the broader establishment and development of the infant microbiome, both taxonomic and functional profiles were dynamic and highly individualized, and dominated in the first year of life by one of three largely exclusive Bifidobacterium species (B. bifidum, B. breve or B. longum) or by the phylum Proteobacteria. In particular, the strain-specific carriage of genes for the utilization of human milk oligosaccharide within a subset of B. longum was present specifically in breast-fed infants. These analyses of TEDDY gut metagenomes provide, to our knowledge, the largest and most detailed longitudinal functional profile of the developing gut microbiome in relation to islet autoimmunity, T1D and other early childhood events. Together with existing evidence from human cohorts7,8 and a T1D mouse model9, these data support the protective effects of short-chain fatty acids in early-onset human T1D.

System network analysis of genomics and transcriptomics data identified type 1 diabetes-associated pathway and genes

Genome-wide association studies (GWASs) have discovered >50 risk loci for type 1 diabetes (T1D). However, those variations only have modest effects on the genetic risk of T1D. In recent years, accumulated studies have suggested that gene-gene interactions might explain part of the missing heritability. The purpose of our research was to identify potential and novel risk genes for T1D by systematically considering the gene-gene interactions through network analyses. We carried out a novel system network analysis of summary GWAS statistics jointly with transcriptomic gene expression data to identify some of the missing heritability for T1D using weighted gene co-expression network analysis (WGCNA). Using WGCNA, seven modules for 1852 nominally significant (P ≤ 0.05) GWAS genes were identified by analyzing microarray data for gene expression profile. One module (tagged as green module) showed significant association (P ≤ 0.05) between the module eigengenes and the trait. This module also displayed a high correlation (r = 0.45, P ≤ 0.05) between module membership (MM) and gene significant (GS), which indicated that the green module of co-expressed genes is of significant biological importance for T1D status. By further describing the module content and topology, the green module revealed a significant enrichment in the "regulation of immune response" (GO:0050776), which is a crucially important pathway in T1D development. Our findings demonstrated a module and several core genes that act as essential components in the etiology of T1D possibly via the regulation of immune response, which may enhance our fundamental knowledge of the underlying molecular mechanisms for T1D.

Immune Mechanisms and Pathways Targeted in Type 1 Diabetes

PURPOSE OF REVIEW

The immunosuppressive agent cyclosporine was first reported to lower daily insulin dose and improve glycemic control in patients with new-onset type 1 diabetes (T1D) in 1984. While renal toxicity limited cyclosporine's extended use, this observation ignited collaborative efforts to identify immunotherapeutic agents capable of safely preserving β cells in patients with or at risk for T1D.

RECENT FINDINGS

Advances in T1D prediction and early diagnosis, together with expanded knowledge of the disease mechanisms, have facilitated trials targeting specific immune cell subsets, autoantigens, and pathways. In addition, clinical responder and non-responder subsets have been defined through the use of metabolic and immunological readouts. Herein, we review emerging T1D biomarkers within the context of recent and ongoing T1D immunotherapy trials. We also discuss responder/non-responder analyses in an effort to identify therapeutic mechanisms, define actionable pathways, and guide subject selection, drug dosing, and tailored combination drug therapy for future T1D trials.

Urinary bisphenol-A levels in children with type 1 diabetes mellitus

BACKGROUND

Bisphenol-A (BPA) is one of the most abundantly produced chemicals globally. Concerns have been raised about BPA's possible role in the pathogenesis of type 1 diabetes mellitus (T1DM). The main aim of the current study was to evaluate the possible association between BPA exposure and T1DM. The second aim was to investigate children's possible BPA exposure routes in Turkey.

METHODS

A total of 100 children aged between 5 and 18 years including 50 children with T1DM and 50 healthy children were included. Urinary BPA levels of all children were measured using high-performance liquid chromatography. Mothers of children enrolled in the study were also requested to complete a survey that included questions on the sociodemographic characteristics, medical history and possible BPA exposure routes of their children.

RESULTS

In the T1DM group, urinary BPA levels were slightly higher compared to the control group, but this difference was not significant (p=0.510). However, there was an inverse relationship between current urinary BPA levels and birth weight. It was found that the use of plastic kettles and the consumption of dairy products in plastic boxes significantly increased the urinary BPA concentrations in all subjects.

CONCLUSIONS

Although there was no significant association between urinary BPA levels and T1DM, we found an inverse relationship between current urinary BPA levels and birth weight. This finding might be important for prenatal exposure, and further prospective research must be conducted. Also, the use of plastic kettles, which has not been mentioned much in the literature before, was found to be an important exposure route for BPA.

Bioinformatics Assembling and Assessment of Novel Coxsackievirus B1 Genome

The human microbiome project via application of metagenomic next-generation sequencing techniques has found surprising large and diverse amounts of microbial sequences across different body sites. There is a wave of investigators studying autoimmune related diseases designing from birth case and control studies to elucidate microbial associations and potential direct triggers. Sequencing analysis, considered big data as it typically includes millions of reads, is challenging but particularly demanding and complex is virome profiling due to its lack of pan-viral genomic signature. Impressively thousands of virus complete genomes have been deposited and these high-quality references are core components of virus profiling pipelines and databases. Still it is commonly known that most viral sequences do not map to known viruses. Moreover human viruses, particularly RNA groups, are notoriously heterogeneous due to high mutation rates. Here, we present the related assembling challenges and a series of bioinformatics steps that were applied in the construction of the complete consensus genome of a novel clinical isolate of Coxsackievirus B1. We further demonstrate our effort in calling mutations between prototype Coxsackievirus B1 sequence from GenBank and serial clinical isolate genome grown in cell culture.

Rs2227982 and rs2227981 in PDCD1 gene are functional SNPs associated with T1D risk in East Asian

AIMS

To investigate whether PDCD1 gene polymorphisms are functional, and their associations with T1D risk and related clinical characteristics.

METHODS

A total of 3060 Chinese Han individuals (1019 T1D patients and 2041 healthy controls) were genotyped for 4 tag single nucleotide polymorphisms (SNPs) within the PDCD1 region (rs2227982, rs7421861, rs10204525, and rs6710479) and another most studied synonymous SNP, rs2227981. In addition, 251 healthy individuals underwent an oral glucose tolerance test (OGTT); measures of insulin release and sensitivity were estimated from insulinogenic, BIGTT, Matsuda. Further, we performed in silico bioinformatics analysis to explore potential functional annotation of the investigated SNPs in PDCD1 gene.

RESULTS

Both rs2227982 and rs2227981 polymorphisms were associated with T1D risk in Chinese Han population under additive model (OR = 0.84, 95% CI 0.75-0.93 and OR = 1.23, 95% CI 1.08-1.40, respectively), but not the other three SNPs in PDCD1 gene. Our meta-analysis revealed that rs2227982 and rs2227981 polymorphisms also have significant associations with T1D risk in East Asians (OR = 0.82, 95% CI 0.74-0.90 and OR = 1.23, 95% CI 1.12-1.36, respectively), but not Europeans. And the T allele of rs2227982 polymorphism is associated with increased 30 min post OGTT glucose level (P = 0.023) and 120 min post OGTT insulin level (P = 0.033). Furthermore, the genetic and regulatory architecture suggested all the 5 investigated SNPs in PDCD1 are putatively functional.

CONCLUSIONS

Both rs2227982 and rs2227981 polymorphisms were associated with T1D risk in East Asians, and rs2227982 also had a significant association with glycemic traits, which suggested PDCD1 gene polymorphisms might participate in facilitating T1D risk.

Class II HLA Genotype Association With First-Phase Insulin Response Is Explained by Islet Autoantibodies

CONTEXT

A declining first-phase insulin response (FPIR) is characteristic of the disease process leading to clinical type 1 diabetes. It is not known whether reduced FPIR depends on class II human leukocyte antigen (HLA) genotype, islet autoimmunity, or both.

OBJECTIVE

To dissect the role of class II HLA DR-DQ genotypes and biochemical islet autoantibodies in the compromised FPIR.

DESIGN, SETTING, PARTICIPANTS

A total of 438 children with defined HLA DR-DQ genotype in the prospective Finnish Type 1 Diabetes Prediction and Prevention Study were analyzed for FPIR in a total of 1149 intravenous glucose tolerance tests and were categorized by their HLA DR-DQ genotype and the number of biochemical islet autoantibodies at the time of the first FPIR. Age-adjusted hierarchical linear mixed models were used to analyze repeated measurements of FPIR.

MAIN OUTCOME MEASURE

The associations between class II HLA DR-DQ genotype, islet autoantibody status, and FPIR.

RESULTS

A strong association between the degree of risk conferred by HLA DR-DQ genotype and positivity for islet autoantibodies existed (P < 0.0001). FPIR was inversely associated with the number of biochemical autoantibodies (P < 0.0001) irrespective of HLA DR-DQ risk group. FPIR decreased over time in children with multiple autoantibodies and increased in children with no biochemical autoantibodies (P < 0.0001 and P = 0.0013, respectively).

CONCLUSIONS

The class II HLA DR-DQ genotype association with FPIR was secondary to the association between HLA and islet autoimmunity. Declining FPIR was associated with positivity for multiple islet autoantibodies irrespective of class II HLA DR-DQ genotype.