Environmental determinants of islet autoimmunity (ENDIA): a pregnancy to early life cohort study in children at-risk of type 1 diabetes

Early Dysglycemia Is Detectable Using Continuous Glucose Monitoring in Very Young Children at Risk of Type 1 Diabetes

OBJECTIVE

Continuous glucose monitoring (CGM) can detect early dysglycemia in older children and adults with presymptomatic type 1 diabetes (T1D) and predict risk of progression to clinical onset. However, CGM data for very young children at greatest risk of disease progression are lacking. This study aimed to investigate the use of CGM data measured in children being longitudinally observed in the Australian Environmental Determinants of Islet Autoimmunity (ENDIA) study from birth to age 10 years.

RESEARCH DESIGN AND METHODS

Between January 2021 and June 2023, 31 ENDIA children with persistent multiple islet autoimmunity (PM Ab+) and 24 age-matched control children underwent CGM assessment alongside standard clinical monitoring. The CGM metrics of glucose SD (SDSGL), coefficient of variation (CEV), mean sensor glucose (SGL), and percentage of time >7.8 mmol/L (>140 mg/dL) were determined and examined for between-group differences.

RESULTS

The mean (SD) ages of PM Ab+ and Ab- children were 4.4 (1.8) and 4.7 (1.9) years, respectively. Eighty-six percent of eligible PM Ab+ children consented to CGM wear, achieving a median (quartile 1 [Q1], Q3) sensor wear period of 12.5 (9.0, 15.0) days. PM Ab+ children had higher median (Q1, Q3) SDSGL (1.1 [0.9, 1.3] vs. 0.9 [0.8, 1.0] mmol/L; P < 0.001) and CEV (17.3% [16.0, 20.9] vs. 14.7% [12.9, 16.6]; P < 0.001). Percentage of time >7.8 mmol/L was greater in PM Ab+ children (median [Q1, Q3] 8.0% [4.4, 13.0] compared with 3.3% [1.4, 5.3] in Ab- children; P = 0.005). Mean SGL did not differ significantly between groups (P = 0.10).

CONCLUSIONS

CGM is feasible and well tolerated in very young children at risk of T1D. Very young PM Ab+ children have increased SDSGL, CEV, and percentage of time >7.8 mmol/L, consistent with prior studies involving older participants.

Dietary patterns during pregnancy and maternal and birth outcomes in women with type 1 diabetes: the Environmental Determinants of Islet Autoimmunity (ENDIA) study

AIMS/HYPOTHESIS

Dietary patterns characterised by high intakes of vegetables may lower the risk of pre-eclampsia and premature birth in the general population. The effect of dietary patterns in women with type 1 diabetes, who have an increased risk of complications in pregnancy, is not known. The aim of this study was to investigate the relationship between dietary patterns and physical activity during pregnancy and maternal complications and birth outcomes in women with type 1 diabetes. We also compared dietary patterns in women with and without type 1 diabetes.

METHODS

Diet was assessed in the third trimester using a validated food frequency questionnaire in participants followed prospectively in the multi-centre Environmental Determinants of Islet Autoimmunity (ENDIA) study. Dietary patterns were characterised by principal component analysis. The Pregnancy Physical Activity Questionnaire was completed in each trimester. Data for maternal and birth outcomes were collected prospectively.

RESULTS

Questionnaires were completed by 973 participants during 1124 pregnancies. Women with type 1 diabetes (n=615 pregnancies with dietary data) were more likely to have a 'fresh food' dietary pattern than women without type 1 diabetes (OR 1.19, 95% CI 1.07, 1.31; p=0.001). In women with type 1 diabetes, an increase equivalent to a change from quartile 1 to 3 in 'fresh food' dietary pattern score was associated with a lower risk of pre-eclampsia (OR 0.37, 95% CI 0.17, 0.78; p=0.01) and premature birth (OR 0.35, 95% CI 0.20, 0.62, p<0.001). These associations were mediated in part by BMI and HbA1c. The 'processed food' dietary pattern was associated with an increased birthweight (β coefficient 56.8 g, 95% CI 2.8, 110.8; p=0.04). Physical activity did not relate to outcomes.

CONCLUSIONS/INTERPRETATION

A dietary pattern higher in fresh foods during pregnancy was associated with sizeable reductions in risk of pre-eclampsia and premature birth in women with type 1 diabetes.

A Review of Stage 0 Biomarkers in Type 1 Diabetes: The Holy Grail of Early Detection and Prevention?

Type 1 diabetes mellitus (T1D) is an incurable autoimmune disease characterized by the destruction of pancreatic islet cells, resulting in lifelong dependency on insulin treatment. There is an abundance of review articles addressing the prediction of T1D; however, most focus on the presymptomatic phases, specifically stages 1 and 2. These stages occur after seroconversion, where therapeutic interventions primarily aim to delay the onset of T1D rather than prevent it. This raises a critical question: what happens before stage 1 in individuals who will eventually develop T1D? Is there a "stage 0" of the disease, and if so, how can we detect it to increase our chances of truly preventing T1D? In pursuit of answers to these questions, this narrative review aimed to highlight recent research in the field of early detection and prediction of T1D, specifically focusing on biomarkers that can predict T1D before the onset of islet autoimmunity. Here, we have compiled influential research from the fields of epigenetics, omics, and microbiota. These studies have identified candidate biomarkers capable of predicting seroconversion from very early stages to several months prior, suggesting that the prophylactic window begins at birth. As the therapeutic landscape evolves from treatment to delay, and ideally from delay to prevention, it is crucial to both identify and validate such "stage 0" biomarkers predictive of islet autoimmunity. In the era of precision medicine, this knowledge will enable early intervention with the potential for delaying, modifying, or completely preventing autoimmunity and T1D in at-risk children.

Environmental Determinants of Islet Autoimmunity (ENDIA) longitudinal prospective pregnancy to childhood cohort study of Australian children at risk of type 1 diabetes: parental demographics and birth information

INTRODUCTION

The Environmental Determinants of Islet Autoimmunity (ENDIA) Study is an ongoing Australian prospective cohort study investigating how modifiable prenatal and early-life exposures drive the development of islet autoimmunity and type 1 diabetes (T1D) in children. In this profile, we describe the cohort's parental demographics, maternal and neonatal outcomes and human leukocyte antigen (HLA) genotypes.

RESEARCH DESIGN AND METHODS

Inclusion criteria were an unborn child, or infant aged less than 6 months, with a first-degree relative (FDR) with T1D. The primary outcome was persistent islet autoimmunity, with children followed until a T1D diagnosis or 10 years of age. Demographic data were collected at enrollment. Lifestyle, clinical and anthropometric data were collected at each visit during pregnancy and clinical pregnancy and birth data were verified against medical case notes. Data were compared between mothers with and without T1D. HLA genotyping was performed on the ENDIA child and all available FDRs.

RESULTS

The final cohort comprised 1473 infants born to 1214 gestational mothers across 1453 pregnancies, with 80% enrolled during pregnancy. The distribution of familial T1D probands was 62% maternal, 28% paternal and 11% sibling. The frequency of high-risk HLA genotypes was highest in T1D probands, followed by ENDIA infants, and lowest among unaffected family members. Mothers with T1D had higher rates of pregnancy complications and perinatal intervention, and larger babies of shorter gestation. Parent demographics were comparable to the Australian population for age, parity and obesity. A greater percentage of ENDIA parents were Australian born, lived in a major city and had higher socioeconomic advantage and education.

CONCLUSIONS

This comprehensive profile provides the context for understanding ENDIA's scope, methodology, unique strengths and limitations. Now fully recruited, ENDIA will provide unique insights into the roles of early-life factors in the development of islet autoimmunity and T1D in the Australian environment.

TRIAL REGISTRATION NUMBER

ACTRN12613000794707.

Prediction of progression to type 1 diabetes with dynamic biomarkers and risk scores

Identifying biomarkers of functional β-cell loss is an important step in the risk stratification of type 1 diabetes. Genetic risk scores (GRS), generated by profiling an array of single nucleotide polymorphisms, are a widely used type 1 diabetes risk-prediction tool. Type 1 diabetes screening studies have relied on a combination of biochemical (autoantibody) and GRS screening methodologies for identifying individuals at high-risk of type 1 diabetes. A limitation of these screening tools is that the presence of autoantibodies marks the initiation of β-cell loss, and is therefore not the best biomarker of progression to early-stage type 1 diabetes. GRS, on the other hand, represents a static biomarker offering a single risk score over an individual's lifetime. In this Personal View, we explore the challenges and opportunities of static and dynamic biomarkers in the prediction of progression to type 1 diabetes. We discuss future directions wherein newer dynamic risk scores could be used to predict type 1 diabetes risk, assess the efficacy of new and emerging drugs to retard, or prevent type 1 diabetes, and possibly replace or further enhance the predictive ability offered by static biomarkers, such as GRS.

Feasibility and Validity of In-Home Self-Collected Capillary Blood Spot Screening for Type 1 Diabetes Risk

Aims: Self-collection of a blood sample for autoantibody testing has potential to facilitate screening for type 1 diabetes risk. We sought to determine the feasibility and acceptability of this approach and the performance of downstream antibody assays. Methods: People living with type 1 diabetes and their family members (N = 97) provided paired capillary blood spot and serum samples collected, respectively, by themselves and a health worker. They provided feedback on the ease, convenience, and painfulness of blood spot collection. Islet antibodies were measured in blood spots by antibody detection by agglutination PCR (ADAP) or multiplex enzyme-linked immunoassay (ELISA), and in serum by radioimmunoassay (RIA) or ELISA. Results: Using serum RIA and ELISA to define antibody status, 50 antibody-negative (Abneg) and 47 antibody-positive (Abpos) participants enrolled, of whom 43 and 47, respectively, returned testable blood spot samples. The majority indicated that self-collection was easier, more convenient, and less painful than formal venesection. The sensitivity and specificity for detection of Abpos by blood spot were, respectively, 85% and 98% for ADAP and 87% and 100% for multiplex ELISA. The specificities by ADAP for each of the four antigen specificities ranged from 98% to 100% and areas under the receiver operator curve from 0.841 to 0.986. Conclusions: Self-collected blood spot sampling is preferred over venesection by research participants. ADAP and multiplex ELISA are highly specific assays for islet antibodies in blood spots with acceptable performance for use alone or in combination to facilitate screening for type 1 diabetes risk. Clinical Trial Registration number: ACTRN12620000510943.

DNA Methylation Near DLGAP2 May Mediate the Relationship between Family History of Type 1 Diabetes and Type 1 Diabetes Risk

Given the differential risk of type 1 diabetes (T1D) in offspring of affected fathers versus affected mothers and our observation that T1D cases have differential DNA methylation near the imprinted DLGAP2 gene compared to controls, we examined whether methylation near DLGAP2 mediates the association between T1D family history and T1D risk. In a nested case-control study of 87 T1D cases and 87 controls from the Diabetes Autoimmunity Study in the Young, we conducted causal mediation analyses at 12 DLGAP2 region CpGs to decompose the effect of family history on T1D risk into indirect and direct effects. These effects were estimated from two regression models adjusted for the human leukocyte antigen DR3/4 genotype: a linear regression of family history on methylation (mediator model) and a logistic regression of family history and methylation on T1D (outcome model). For 8 of the 12 CpGs, we identified a significant interaction between T1D family history and methylation on T1D risk. Accounting for this interaction, we found that the increased risk of T1D for children with affected mothers compared to those with no family history was mediated through differences in methylation at two CpGs (cg27351978, cg00565786) in the DLGAP2 region, as demonstrated by a significant pure natural indirect effect (odds ratio (OR) = 1.98, 95% confidence interval (CI): 1.06-3.71) and nonsignificant total natural direct effect (OR = 1.65, 95% CI: 0.16-16.62) (for cg00565786). In contrast, the increased risk of T1D for children with an affected father or sibling was not explained by DNA methylation changes at these CpGs. Results were similar for cg27351978 and robust in sensitivity analyses. Lastly, we found that DNA methylation in the DLGAP2 region was associated (P<0:05) with gene expression of nearby protein-coding genes DLGAP2, ARHGEF10, ZNF596, and ERICH1. Results indicate that the maternal protective effect conferred through exposure to T1D in utero may operate through changes to DNA methylation that have functional downstream consequences.

A surge in serum mucosal cytokines associated with seroconversion in children at risk for type 1 diabetes

AIMS/INTRODUCTION

Autoantibodies to pancreatic islet antigens identify young children at high risk of type 1 diabetes. On a background of genetic susceptibility, islet autoimmunity is thought to be driven by environmental factors, of which enteric viruses are prime candidates. We sought evidence for enteric pathology in children genetically at-risk for type 1 diabetes followed from birth who had developed islet autoantibodies ("seroconverted"), by measuring mucosa-associated cytokines in their sera.

MATERIALS AND METHODS

Sera were collected 3 monthly from birth from children with a first-degree type 1 diabetes relative, in the Environmental Determinants of Islet Autoimmunity (ENDIA) study. Children who seroconverted were matched for sex, age, and sample availability with seronegative children. Luminex xMap technology was used to measure serum cytokines.

RESULTS

Of eight children who seroconverted, for whom serum samples were available at least 6 months before and after seroconversion, the serum concentrations of mucosa-associated cytokines IL-21, IL-22, IL-25, and IL-10, the Th17-related cytokines IL-17F and IL-23, as well as IL-33, IFN-γ, and IL-4, peaked from a low baseline in seven around the time of seroconversion and in one preceding seroconversion. These changes were not detected in eight sex- and age-matched seronegative controls, or in a separate cohort of 11 unmatched seronegative children.

CONCLUSIONS

In a cohort of children at risk for type 1 diabetes followed from birth, a transient, systemic increase in mucosa-associated cytokines around the time of seroconversion lends support to the view that mucosal infection, e.g., by an enteric virus, may drive the development of islet autoimmunity.

Possible heterogeneity of initial pancreatic islet beta-cell autoimmunity heralding type 1 diabetes

The etiology of type 1 diabetes (T1D) foreshadows the pancreatic islet beta-cell autoimmune pathogenesis that heralds the clinical onset of T1D. Standardized and harmonized tests of autoantibodies against insulin (IAA), glutamic acid decarboxylase (GADA), islet antigen-2 (IA-2A), and ZnT8 transporter (ZnT8A) allowed children to be followed from birth until the appearance of a first islet autoantibody. In the Environmental Determinants of Diabetes in the Young (TEDDY) study, a multicenter (Finland, Germany, Sweden, and the United States) observational study, children were identified at birth for the T1D high-risk HLA haploid genotypes DQ2/DQ8, DQ2/DQ2, DQ8/DQ8, and DQ4/DQ8. The TEDDY study was preceded by smaller studies in Finland, Germany, Colorado, Washington, and Sweden. The aims were to follow children at increased genetic risk to identify environmental factors that trigger the first-appearing autoantibody (etiology) and progress to T1D (pathogenesis). The larger TEDDY study found that the incidence rate of the first-appearing autoantibody was split into two patterns. IAA first peaked already during the first year of life and tapered off by 3-4 years of age. GADA first appeared by 2-3 years of age to reach a plateau by about 4 years. Prior to the first-appearing autoantibody, genetic variants were either common or unique to either pattern. A split was also observed in whole blood transcriptomics, metabolomics, dietary factors, and exposures such as gestational life events and early infections associated with prolonged shedding of virus. An innate immune reaction prior to the adaptive response cannot be excluded. Clarifying the mechanisms by which autoimmunity is triggered to either insulin or GAD65 is key to uncovering the etiology of autoimmune T1D.

A multi-centre investigation of macrovascular and non-ocular microvascular complications in children and adolescents with diabetes mellitus in southern Ghana

Objectives

To investigate the prevalence of macrovascular and non-ocular microvascular complications and the associated factors among children and adolescents with diabetes mellitus in selected hospitals in southern Ghana.

Design

A cross-sectional study.

Setting

The out-patient clinics of the Departments of Child Health, Medicine and Therapeutics, Family Medicine, Ophthalmology, and the National Diabetes Management and Research Centre, all at the Korle Bu Teaching Hospital, Accra, as well as from Cape-Coast Teaching Hospital in the Central Region of Ghana.

Participants

Fifty-eight children and adolescents aged 4-19 years who had been diagnosed with diabetes mellitus.

Main outcome measures

Macrovascular (peripheral artery disease and coronary heart disease) and non-ocular microvascular complications (neuropathy and nephropathy).

Results

Data from 58 children and adolescents with diabetes were analysed. The mean age of participants was 14.6±2.6 years, and a female preponderance was observed (45, 77.6%). The prevalence of macrovascular and non-ocular microvascular complications was 27.6% and 8.6%, respectively. Long duration of diabetes diagnosis (p=0.044) and low triglycerides (p=0.009) were associated with microvascular complications, while high triglycerides (p=0.032), lower HDL cholesterol (p=0.046), and abnormal body mass index (p=0.020) were associated with macrovascular complications.

Conclusions

Macrovascular and non-ocular microvascular complications are common among children and adolescents with diabetes in southern Ghana and are associated with a long duration of diabetes diagnosis, abnormal body mass index, low HDL cholesterol, and triglyceride levels. Therefore, the early institution of regular screening for diabetes-related complications to allow early detection and appropriate management is recommended.

Funding

University of Ghana Research Fund.

Parallel recovery of chromatin accessibility and gene expression dynamics from frozen human regulatory T cells

Epigenetic features such as DNA accessibility dictate transcriptional regulation in a cell type- and cell state- specific manner, and mapping this in health vs. disease in clinically relevant material is opening the door to new mechanistic insights and new targets for therapy. Assay for Transposase Accessible Chromatin Sequencing (ATAC-seq) allows chromatin accessibility profiling from low cell input, making it tractable on rare cell populations, such as regulatory T (Treg) cells. However, little is known about the compatibility of the assay with cryopreserved rare cell populations. Here we demonstrate the robustness of an ATAC-seq protocol comparing primary Treg cells recovered from fresh or cryopreserved PBMC samples, in the steady state and in response to stimulation. We extend this method to explore the feasibility of conducting simultaneous quantitation of chromatin accessibility and transcriptome from a single aliquot of 50,000 cryopreserved Treg cells. Profiling of chromatin accessibility and gene expression in parallel within the same pool of cells controls for cellular heterogeneity and is particularly beneficial when constrained by limited input material. Overall, we observed a high correlation of accessibility patterns and transcription factor dynamics between fresh and cryopreserved samples. Furthermore, highly similar transcriptomic profiles were obtained from whole cells and from the supernatants recovered from ATAC-seq reactions. We highlight the feasibility of applying these techniques to profile the epigenomic landscape of cells recovered from cryopreservation biorepositories.

Experiences of Caregivers and At-Risk Children Enrolled in a Prospective Pregnancy-Birth Cohort Study into the Causes of Type 1 Diabetes: The ENDIA Study

Background: We sought research experiences of caregivers and their children were enrolled in the Environmental Determinants of Islet Autoimmunity (ENDIA) study. Methods: ENDIA is a pregnancy–birth cohort investigating early-life causes of type 1 diabetes (T1D). Surveys were sent to 1090 families between June 2021 and March 2022 with a median participation of >5 years. Caregivers completed a 12-item survey. Children ≥ 3 years completed a four-item survey. Results: The surveys were completed by 550/1090 families (50.5%) and 324/847 children (38.3%). The research experience was rated as either “excellent” or “good” by 95% of caregivers, and 81% of children were either “ok”, “happy” or “very happy”. The caregivers were motivated by contributing to research and monitoring their children for T1D. Relationships with the research staff influenced the experience. The children most liked virtual reality headsets, toys, and “helping”. Blood tests were least liked by the children and were the foremost reason that 23.4% of the caregivers considered withdrawing. The children valued gifts more than their caregivers. Only 5.9% of responses indicated dissatisfaction with some aspects of the protocol. The self-collection of samples in regional areas, or during the COVID-19 pandemic restrictions, were accepted. Conclusions: This evaluation identified modifiable protocol elements and was conducted to further improve satisfaction. What was important to the children was distinct from their caregivers.

A Long-Term Evaluation of Facebook for Recruitment and Retention in the ENDIA Type 1 Diabetes Pregnancy-Birth Cohort Study

BACKGROUND

The Environmental Determinants of Islet Autoimmunity (ENDIA) study is an Australia-wide pregnancy-birth cohort study following children who have a first-degree relative with type 1 diabetes (ACTRN1261300794707). A dedicated ENDIA Facebook page was established in 2013 with the aim of enhancing recruitment and supporting participant retention through dissemination of study information. To measure the impact of Facebook, we evaluated the sources of referral to the study, cohort demographics, and withdrawal rates. We also investigated whether engagement with Facebook content was associated with specific post themes.

METHODS

Characteristics of Facebook versus conventional recruits were compared using linear, logistic, and multinomial logistic regression models. Logistic regression was used to determine the risk of study withdrawal. Data pertaining to 794 Facebook posts over 7.5 years were included in the analysis.

RESULTS

Facebook was the third largest source of referral (300/1511; 19.9%). Facebook recruits were more frequently Australian-born (P < .001) enrolling postnatally (P = .01) and withdrew from the study at a significantly lower rate compared with conventional recruits (4.7% vs 12.3%; P < .001) after a median of follow-up of 3.3 years. Facebook content featuring stories and images of participants received the highest engagement even though <20% of the 2337 Facebook followers were enrolled in the study.

CONCLUSIONS

Facebook was a valuable recruitment tool for ENDIA. Compared with conventional recruits, Facebook recruits were three times less likely to withdraw during long-term follow-up and had different sociodemographic characteristics. Facebook content featuring participants was the most engaging. These findings inform social media strategies for future cohort and type 1 diabetes studies.

TRIAL REGISTRATION

Australia New Zealand Clinical Trials Registry: ACTRN1261300794707.

Mental Health During Late Pregnancy and Postpartum in Mothers With and Without Type 1 Diabetes: The ENDIA Study

OBJECTIVE

Pregnancy and type 1 diabetes are each associated with increased anxiety and depression, but the combined impact on well-being is unresolved. We compared the mental health of women with and without type 1 diabetes during pregnancy and postpartum and examined the relationship between mental health and glycemic control.

RESEARCH DESIGN AND METHODS

Participants were women enrolled from 2016 to 2020 in the Environmental Determinants of Islet Autoimmunity (ENDIA) study, a pregnancy to birth prospective cohort following children with a first-degree relative with type 1 diabetes. Edinburgh Postnatal Depression Scale (EPDS) and Perceived Stress Scale (PSS) were completed during the third trimester (T3) (median [interquartile range] 34 [32, 36] weeks) and postpartum (14 [13, 16] weeks) by 737 women (800 pregnancies) with (n = 518) and without (n = 282) type 1 diabetes.

RESULTS

EPDS and PSS scores did not differ between women with and without type 1 diabetes during T3 and postpartum. EPDS scores were marginally higher in T3: predicted mean (95% CI) 5.7 (5.4, 6.1) than postpartum: 5.3 (5.0, 5.6), independent of type 1 diabetes status (P = 0.01). HbA1c levels in type 1 diabetes were 6.3% [5.8, 6.9%] in T3 and did not correlate with EPDS or PSS scores. Reported use of psychotropic medications was similar in women with (n = 44 of 518 [8%]) and without type 1 diabetes (n = 17 of 282 [6%]), as was their amount of physical activity.

CONCLUSIONS

Overall, mental health in late pregnancy and postpartum did not differ between women with and without type 1 diabetes, and mental health scores were not correlated with glycemic control.

Women with type 1 diabetes exhibit a progressive increase in gut Saccharomyces cerevisiae in pregnancy associated with evidence of gut inflammation

AIMS

Studies of the gut microbiome have focused on its bacterial composition. We aimed to characterize the gut fungal microbiome (mycobiome) across pregnancy in women with and without type 1 diabetes.

METHODS

Faecal samples (n = 162) were collected from 70 pregnant women (45 with and 25 without type 1 diabetes) across all trimesters. Fungi were analysed by internal transcribed spacer 1 amplicon sequencing. Markers of intestinal inflammation (faecal calprotectin) and intestinal epithelial integrity (serum intestinal fatty acid binding protein; I-FABP), and serum antibodies to Saccharomyces cerevisiae (ASCA) were measured.

RESULTS

Women with type 1 diabetes had decreased fungal alpha diversity by the third trimester, associated with an increased abundance of Saccharomyces cerevisiae that was inversely related to the abundance of the anti-inflammatory butyrate-producing bacterium Faecalibacterium prausnitzii. Women with type 1 diabetes had higher concentrations of calprotectin, I-FABP and ASCA.

CONCLUSIONS

Women with type 1 diabetes exhibit a shift in the gut mycobiome across pregnancy associated with evidence of gut inflammation and impaired intestinal barrier function. The relevance of these findings to the higher rate of pregnancy complications in type 1 diabetes warrants further study.

The virome in early life and childhood and development of islet autoimmunity and type 1 diabetes: A systematic review and meta-analysis of observational studies

Viruses are postulated as primary candidate triggers of islet autoimmunity (IA) and type 1 diabetes (T1D), based on considerable epidemiological and experimental evidence. Recent studies have investigated the association between all viruses (the 'virome') and IA/T1D using metagenomic next-generation sequencing (mNGS). Current associations between the early life virome and the development of IA/T1D were analysed in a systematic review and meta-analysis of human observational studies from Medline and EMBASE (published 2000-June 2020), without language restriction. Inclusion criteria were as follows: cohort and case-control studies examining the virome using mNGS in clinical specimens of children ≤18 years who developed IA/T1D. The National Health and Medical Research Council level of evidence scale and Newcastle-Ottawa scale were used for study appraisal. Meta-analysis for exposure to specific viruses was performed using random-effects models, and the strength of association was measured using odds ratios (ORs) and 95% confidence intervals (CIs). Eligible studies (one case-control, nine nested case-control) included 1,425 participants (695 cases, 730 controls) and examined IA (n = 1,023) or T1D (n = 402). Meta-analysis identified small but significant associations between IA and number of stool samples positive for all enteroviruses (OR 1.14, 95% CI 1.00-1.29, p = 0.05; heterogeneity χ2  = 1.51, p = 0.68, I2  = 0%), consecutive positivity for enteroviruses (1.55, 1.09-2.20, p = 0.01; χ2  = 0.19, p = 0.91, I2  = 0%) and number of stool samples positive specifically for enterovirus B (1.20, 1.01-1.42, p = 0.04; χ2  = 0.03, p = 0.86, I2  = 0%). Virome analyses to date have demonstrated associations between enteroviruses and IA that may be clinically significant. However, larger prospective mNGS studies with more frequent sampling and follow-up from pregnancy are required to further elucidate associations between early virus exposure and IA/T1D.

Type 1 diabetes in pregnancy is associated with distinct changes in the composition and function of the gut microbiome

BACKGROUND

The gut microbiome changes in response to a range of environmental conditions, life events and disease states. Pregnancy is a natural life event that involves major physiological adaptation yet studies of the microbiome in pregnancy are limited and their findings inconsistent. Pregnancy with type 1 diabetes (T1D) is associated with increased maternal and fetal risks but the gut microbiome in this context has not been characterized. By whole metagenome sequencing (WMS), we defined the taxonomic composition and function of the gut bacterial microbiome across 70 pregnancies, 36 in women with T1D.

RESULTS

Women with and without T1D exhibited compositional and functional changes in the gut microbiome across pregnancy. Profiles in women with T1D were distinct, with an increase in bacteria that produce lipopolysaccharides and a decrease in those that produce short-chain fatty acids, especially in the third trimester. In addition, women with T1D had elevated concentrations of fecal calprotectin, a marker of intestinal inflammation, and serum intestinal fatty acid-binding protein (I-FABP), a marker of intestinal epithelial damage.

CONCLUSIONS

Women with T1D exhibit a shift towards a more pro-inflammatory gut microbiome during pregnancy, associated with evidence of intestinal inflammation. These changes could contribute to the increased risk of pregnancy complications in women with T1D and are potentially modifiable by dietary means. Video abstract.

Viruses and Type 1 Diabetes: From Enteroviruses to the Virome

For over a century, viruses have left a long trail of evidence implicating them as frequent suspects in the development of type 1 diabetes. Through vigorous interrogation of viral infections in individuals with islet autoimmunity and type 1 diabetes using serological and molecular virus detection methods, as well as mechanistic studies of virus-infected human pancreatic β-cells, the prime suspects have been narrowed down to predominantly human enteroviruses. Here, we provide a comprehensive overview of evidence supporting the hypothesised role of enteroviruses in the development of islet autoimmunity and type 1 diabetes. We also discuss concerns over the historical focus and investigation bias toward enteroviruses and summarise current unbiased efforts aimed at characterising the complete population of viruses (the “virome”) contributing early in life to the development of islet autoimmunity and type 1 diabetes. Finally, we review the range of vaccine and antiviral drug candidates currently being evaluated in clinical trials for the prevention and potential treatment of type 1 diabetes.

Epigenetic Changes Induced by Maternal Factors during Fetal Life: Implication for Type 1 Diabetes

Organ-specific autoimmune diseases, such as type 1 diabetes, are believed to result from T-cell-mediated damage of the target tissue. The immune-mediated tissue injury, in turn, is known to depend on complex interactions between genetic and environmental factors. Nevertheless, the mechanisms whereby environmental factors contribute to the pathogenesis of autoimmune diseases remain elusive and represent a major untapped target to develop novel strategies for disease prevention. Given the impact of the early environment on the developing immune system, epigenetic changes induced by maternal factors during fetal life have been linked to a likelihood of developing an autoimmune disease later in life. In humans, DNA methylation is the epigenetic mechanism most extensively investigated. This review provides an overview of the critical role of DNA methylation changes induced by prenatal maternal conditions contributing to the increased risk of immune-mediated diseases on the offspring, with a particular focus on T1D. A deeper understanding of epigenetic alterations induced by environmental stressors during fetal life may be pivotal for developing targeted prevention strategies of type 1 diabetes by modifying the maternal environment.

Diagnosis and treatment of type 1 diabetes at the dawn of the personalized medicine era

Type 1 diabetes affects millions of people globally and requires careful management to avoid serious long-term complications, including heart and kidney disease, stroke, and loss of sight. The type 1 diabetes patient cohort is highly heterogeneous, with individuals presenting with disease at different stages and severities, arising from distinct etiologies, and overlaying varied genetic backgrounds. At present, the “one-size-fits-all” treatment for type 1 diabetes is exogenic insulin substitution therapy, but this approach fails to achieve optimal blood glucose control in many individuals. With advances in our understanding of early-stage diabetes development, diabetes stratification, and the role of genetics, type 1 diabetes is a promising candidate for a personalized medicine approach, which aims to apply “the right therapy at the right time, to the right patient”. In the case of type 1 diabetes, great efforts are now being focused on risk stratification for diabetes development to enable pre-clinical detection, and the application of treatments such as gene therapy, to prevent pancreatic destruction in a sub-set of patients. Alongside this, breakthroughs in stem cell therapies hold great promise for the regeneration of pancreatic tissues in some individuals. Here we review the recent initiatives in the field of personalized medicine for type 1 diabetes, including the latest discoveries in stem cell and gene therapy for the disease, and current obstacles that must be overcome before the dream of personalized medicine for all type 1 diabetes patients can be realized.

Early Nutrition and Risk of Type 1 Diabetes: The Role of Gut Microbiota

Type 1 diabetes (T1D) appears most frequently in childhood, with an alarming increasing incidence in the last decades. Although the genetic predisposition is a major risk factor, it cannot solely explain the complex etiology of T1D which is still not fully understood. In this paper, we reviewed the most recent findings on the role of early nutrition and the involvement of the gut microbiota in the etiopathogenesis of T1D. The main conclusions that are withdrawn from the current literature regarding alleviating the risk of developing T1D through nutrition are the encouragement of long-term breast-feeding for at least the first 6 months of life and the avoidance of early complementary foods and gluten introduction (before 4 months of age) as well as cow milk introduction before 12 months of life. These detrimental feeding habits create a gut microbiota dysbiotic state that can contribute to the onset of T1D in infancy. Finally, we discussed the possibility to introduce probiotics, prebiotics and post-biotics in the prevention of T1D.

Type 1 diabetes can present before the age of 6 months and is characterised by autoimmunity and rapid loss of beta cells

AIMS/HYPOTHESIS

Diabetes diagnosed at <6 months of age is usually monogenic. However, 10-15% of affected infants do not have a pathogenic variant in one of the 26 known neonatal diabetes genes. We characterised infants diagnosed at <6 months of age without a pathogenic variant to assess whether polygenic type 1 diabetes could arise at early ages.

METHODS

We studied 166 infants diagnosed with type 1 diabetes at <6 months of age in whom pathogenic variants in all 26 known genes had been excluded and compared them with infants with monogenic neonatal diabetes (n = 164) or children with type 1 diabetes diagnosed at 6-24 months of age (n = 152). We assessed the type 1 diabetes genetic risk score (T1D-GRS), islet autoantibodies, C-peptide and clinical features.

RESULTS

We found an excess of infants with high T1D-GRS: 38% (63/166) had a T1D-GRS >95th centile of healthy individuals, whereas 5% (8/166) would be expected if all were monogenic (p < 0.0001). Individuals with a high T1D-GRS had a similar rate of autoantibody positivity to that seen in individuals with type 1 diabetes diagnosed at 6-24 months of age (41% vs 58%, p = 0.2), and had markedly reduced C-peptide levels (median <3 pmol/l within 1 year of diagnosis), reflecting rapid loss of insulin secretion. These individuals also had reduced birthweights (median z score -0.89), which were lowest in those diagnosed with type 1 diabetes at <3 months of age (median z score -1.98).

CONCLUSIONS/INTERPRETATION

We provide strong evidence that type 1 diabetes can present before the age of 6 months based on individuals with this extremely early-onset diabetes subtype having the classic features of childhood type 1 diabetes: high genetic risk, autoimmunity and rapid beta cell loss. The early-onset association with reduced birthweight raises the possibility that for some individuals there was reduced insulin secretion in utero. Comprehensive genetic testing for all neonatal diabetes genes remains essential for all individuals diagnosed with diabetes at <6 months of age. Graphical abstract.

Changes in pancreatic exocrine function in young at-risk children followed to islet autoimmunity and type 1 diabetes in the ENDIA study

BACKGROUNDS

We aimed to monitor pancreatic exocrine function longitudinally in relation to the development of islet autoimmunity (IA) and type 1 diabetes (T1D) in at-risk children with a first-degree relative with T1D, who were followed prospectively in the Environmental Determinants of Islet Autoimmunity (ENDIA) study.

METHODS

Fecal elastase-1 (FE-1) concentration was measured longitudinally in 85 ENDIA children from median age 1.0 (IQR 0.7,1.3) year. Twenty-eight of 85 children (progressors) developed persistent islet autoantibodies at median age of 1.5 (IQR 1.1,2.5) years, of whom 11 went on to develop clinical diabetes. The other 57 islet autoantibody-negative children (non-progressors) followed similarly were age and gender-matched with the progressors. An adjusted linear mixed model compared FE-1 concentrations in progressors and non-progressors.

RESULTS

Baseline FE-1 did not differ between progressors and non-progressors, or by HLA DR type or proband status. FE-1 decreased over time in progressors in comparison to non-progressors (Wald statistic 5.46, P = .02); in some progressors the fall in FE-1 preceded the onset of IA.

CONCLUSIONS

Pancreatic exocrine function decreases in the majority of young at-risk children who progress to IA and T1D.

Pancreas size and exocrine function is decreased in young children with recent-onset Type 1 diabetes

AIMS

To measure pancreatic area and exocrine function in young children with recent-onset Type 1 diabetes to determine whether the exocrine pancreas is also affected in the pathophysiology of early childhood diabetes.

METHODS

Thirty-two children (14 boys) aged 5.5 (4.5, 7.3) median (IQR) years presenting with recent-onset Type 1 diabetes and 90 controls (44 boys) of similar age had ultrasound imaging of the pancreas. Children with Type 1 diabetes were receiving insulin and were without ketosis. Transverse and longitudinal areas of the pancreas were measured by digitalized outline. Pancreatic faecal elastase-1 was analysed using an enzyme-linked immunosorbent assay kit in recent-onset Type 1 diabetes and 38 first-degree relative control children.

RESULTS

Pancreatic area and exocrine function were reduced in Type 1 diabetes. Mean transverse area (SD) in Type 1 diabetes was 6.82 cm² (1.61) vs. 8.31 cm² (1.74) in controls, adjusted estimate (95% CI) 1.45 (-2.12, -0.79), P < 0.001; longitudinal area was 1.28 cm² (0.44) vs. 1.55 cm² (0.43), adjusted estimate (95% CI) -0.27 (-0.45, -0.09), P = 0.003. Faecal elastase-1 levels in Type 1 diabetes were 455 (323, 833) ug/g, median (IQR) vs. 1408 μg/g (1031, 1989) in controls, P < 0.001.

CONCLUSION

Pancreatic area and accompanying subclinical exocrine function were reduced in very young children with recent-onset Type 1 diabetes. This supports changes in the exocrine pancreas in the pathophysiology of Type 1 diabetes presenting in early life.

Effect of maternal smoking during pregnancy on childhood type 1 diabetes: a whole-of-population study

AIMS/HYPOTHESIS

Evidence of an association between maternal smoking during pregnancy (prenatal smoking) and childhood type 1 diabetes is mixed. Previous studies have been small and potentially biased due to unmeasured confounding. The objectives of this study were to estimate the association between prenatal smoking and childhood type 1 diabetes, assess residual confounding with a negative control design and an E-value analysis, and summarise published effect estimates from a meta-analysis.

METHODS

This whole-of-population study (births from 1999 to 2013, participants aged ≤15 years) used de-identified linked administrative data from the South Australian Early Childhood Data Project. Type 1 diabetes was diagnosed in 557 children (ICD, tenth edition, Australian Modification [ICD-10-AM] codes: E10, E101-E109) during hospitalisation (2001-2014). Families not given financial assistance for school fees was a negative control outcome. Adjusted Cox proportional HRs were calculated. Analyses were conducted on complete-case (n = 264,542, type 1 diabetes = 442) and imputed (n = 286,058, type 1 diabetes = 557) data. A random-effects meta-analysis was used to summarise the effects of prenatal smoking on type 1 diabetes.

RESULTS

Compared with non-smokers, children exposed to maternal smoking only in the first or second half of pregnancy had a 6% higher type 1 diabetes incidence (adjusted HR 1.06 [95% CI 0.73, 1.55]). Type 1 diabetes incidence was 24% lower (adjusted HR 0.76 [95% CI 0.58, 0.99]) among children exposed to consistent prenatal smoking, and 16% lower for exposure to any maternal smoking in pregnancy (adjusted HR 0.84 [95% CI 0.67, 1.08]), compared with the unexposed group. Meta-analytic estimates showed 28-29% lower risk of type 1 diabetes among children exposed to prenatal smoking compared with those not exposed. The negative control outcome analysis indicated residual confounding in the prenatal smoking and type 1 diabetes association. E-value analysis indicated that unmeasured confounding associated with prenatal smoking and childhood type 1 diabetes, with a HR of 1.67, could negate the observed effect.

CONCLUSIONS/INTERPRETATION

Our best estimate from the study is that maternal smoking in pregnancy was associated with 16% lower childhood type 1 diabetes incidence, and some of this effect was due to residual confounding.

Early-life factors contributing to type 1 diabetes

The incidence of type 1 diabetes has increased since the mid-twentieth century at a rate that is too rapid to be attributed to genetic predisposition alone. While the disease can occur at any age, mounting evidence from longitudinal cohort studies of at-risk children indicate that type 1 diabetes associated autoantibodies can be present from the first year of life, and that those who develop type 1 diabetes at a young age have a more aggressive form of the disease. This corroborates the hypothesis that environmental exposures in early life contribute to type 1 diabetes risk, whether related to maternal influences on the fetus during pregnancy, neonatal factors or later effects during infancy and early childhood. Studies to date show a range of environmental triggers acting at different time points, suggesting a multifactorial model of genetic and environmental factors in the pathogenesis of type 1 diabetes, which integrally involves a dialogue between the immune system and pancreatic beta cells. For example, breastfeeding may have a weak protective effect on type 1 diabetes risk, while use of an extensively hydrolysed formula does not. Additionally, exposure to being overweight pre-conception, both in utero and postnatally, is associated with increased risk of type 1 diabetes. Epidemiological, clinical and pathological studies in humans support a role for viral infections, particularly enteroviruses, in type 1 diabetes, but definitive proof is lacking. The role of the early microbiome and its perturbations in islet autoimmunity and type 1 diabetes is the subject of investigation in ongoing cohort studies. Understanding the interactions between environmental exposures and the human genome and metagenome, particularly across ethnically diverse populations, will be critical for the development of future strategies for primary prevention of type 1 diabetes.

Distinct Gut Virome Profile of Pregnant Women With Type 1 Diabetes in the ENDIA Study

Background

The importance of gut bacteria in human physiology, immune regulation, and disease pathogenesis is well established. In contrast, the composition and dynamics of the gut virome are largely unknown; particularly lacking are studies in pregnancy. We used comprehensive virome capture sequencing to characterize the gut virome of pregnant women with and without type 1 diabetes (T1D), longitudinally followed in the Environmental Determinants of Islet Autoimmunity study.

Methods

In total, 61 pregnant women (35 with T1D and 26 without) from Australia were examined. Nucleic acid was extracted from serial fecal specimens obtained at prenatal visits, and viral genomes were sequenced by virome capture enrichment. The frequency, richness, and abundance of viruses were compared between women with and without T1D.

Results

Two viruses were more prevalent in pregnant women with T1D: picobirnaviruses (odds ratio [OR], 4.2; 95% confidence interval [CI], 1.0–17.1; P = .046) and tobamoviruses (OR, 3.2; 95% CI, 1.1–9.3; P = .037). The abundance of 77 viruses significantly differed between the 2 maternal groups (≥2-fold difference; P < .02), including 8 Enterovirus B types present at a higher abundance in women with T1D.

Conclusions

These findings provide novel insight into the composition of the gut virome during pregnancy and demonstrate a distinct profile of viruses in women with T1D.

Minimal variation of the plasma lipidome after delayed processing of neonatal cord blood

BACKGROUND

Cord blood lipids are potential disease biomarkers. We aimed to determine if their concentrations were affected by delayed blood processing.

METHOD

Refrigerated cord blood from six healthy newborns was centrifuged every 12 h for 4 days. Plasma lipids were analysed by liquid chromatography/mass spectroscopy.

RESULTS

Of 262 lipids identified, only eight varied significantly over time. These comprised three dihexosylceramides, two phosphatidylserines and two phosphatidylethanolamines whose relative concentrations increased and one sphingomyelin that decreased.

CONCLUSION

Delay in separation of plasma from refrigerated cord blood has minimal effect overall on the plasma lipidome.

Influence of fecal collection conditions and 16S rRNA gene sequencing at two centers on human gut microbiota analysis

To optimise fecal sampling for reproducible analysis of the gut microbiome, we compared different methods of sample collection and sequencing of 16S rRNA genes at two centers. Samples collected from six individuals on three consecutive days were placed in commercial collection tubes (OMNIgeneGut OMR-200) or in sterile screw-top tubes in a home fridge or home freezer for 6-24 h, before transfer and storage at -80 °C. Replicate samples were shipped to centers in Australia and the USA for DNA extraction and sequencing by their respective PCR protocols, and analysed with the same bioinformatic pipeline. Variation in gut microbiome was dominated by differences between individuals. Minor differences in the abundance of taxa were found between collection-processing methods and day of collection, and between the two centers. We conclude that collection with storage and transport at 4 °C within 24 h is adequate for 16S rRNA analysis of the gut microbiome. Other factors including differences in PCR and sequencing methods account for relatively minor variation compared to differences between individuals.

Type 1 diabetes: a disease of developmental origins

The incidence of type 1 diabetes globally has increased dramatically over the last 50 years. Proposed environmental reasons for this increase mirror the modern lifestyle. Type 1 diabetes can be viewed as part of the non- communicable disease epidemic in our modern society. Meanwhile rapidly evolving new technologies are advancing our understanding of how human microbial communities interface with the immune system and metabolism, and how the modern pro-inflammatory environment is changing these communities and contributing to the rapid rise of non-communicable disease. The majority of children who present with clinical type 1 diabetes are of school age; however 80% of children who develop type 1 diabetes by 18 years of age will have detectable islet autoantibodies by 3 years of age. The evolving concept that type 1 diabetes in many children has developmental origins has directed research questions in search of prevention back to pregnancy and early life. To this end the world's first pregnancy to early childhood cohort study in at-risk children has commenced.

Modulation of type 1 and type 2 diabetes risk by the intestinal microbiome

The prevalence of type 1 and type 2 diabetes have both risen dramatically over the last 50 years. Recent findings point towards the gut microbiota as a potential contributor to these trends. The hundred trillion bacteria residing in the mammalian gut have established a symbiotic relation with their host and influence many aspects of host metabolism, physiology, and immunity. In this review, we examine recent data linking gut microbiome composition and function to anti-pancreatic immunity, insulin-resistance, and obesity. Studies in rodents and human longitudinal studies suggest that an altered gut microbiome characterized by lower diversity and resilience is associated with type 1 and type 2 diabetes. Through its metabolites and enzymatic arsenal, the microbiota shape host metabolism, energy extracted from the diet and contribute to the normal development of the immune system and to tissue inflammation. Increasing evidence underscores the importance of the maternal microbiome, the gestational environment and the conditions of newborn delivery in establishing the gut microbiota of the offspring. Perturbations of the maternal microbiome during gestation, or that of the offspring during early infant development may promote a pro-inflammatory environment conducive to the development of autoimmunity and metabolic disturbance. Collectively the findings reviewed herein underscore the need for mechanistic investigations in rodent models and in human studies to better define the relationships between microbial and host inflammatory activity in diabetes, and to evaluate the potential of microbe-derived therapeutics in the prevention and treatment of both forms of diabetes.

JDRF's vision and strategy for prevention of type 1 diabetes

The increasing incidence and lower threshold of developing type 1 diabetes (T1D) increases the urgency of its prevention. Insights from past and current natural history studies have provided the framework for a compelling strategy for primary and secondary prevention. Primary prevention of T1D should target the general childhood population with vaccines (viral or tolerogenic) or by altering microbiota-induced immunoregulation. Secondary prevention will likely require combination therapies (anti-inflammatories, immunomodulatory agents, beta cell survival agents, and/or agents improving glucose control) used sequentially or simultaneously to preserve residual beta cell function and prevent symptomatic disease. Critical gaps and challenges for prevention of T1D include an incomplete understanding of disease pathogenesis and heterogeneity, the lack of cost-effective risk screening and validated biomarkers for precise staging of disease and optimizing design of shorter and smaller prevention clinical trials, and the lack of appreciation of the impact and burden of T1D and the potential for its prevention. A comprehensive and concerted effort of funders, academia, industry, regulatory authorities, payers, government bodies, health care providers, and the T1D community will be required to deliver on JDRF's vision and strategy for prevention of T1D.

Analysis of antigen specific T cells in diabetes - Lessons from pre-clinical studies and early clinical trials

Antigen-specific immune tolerance promises to provide safe and effective therapies to prevent type 1 diabetes (T1D). Antigen-specific therapy requires two components: well-defined, clinically relevant autoantigens; and safe approaches to inducing tolerance in T cells specific for these antigens. Proinsulin is a critical autoantigen in both NOD mice, based on knockout mouse studies and induction of immune tolerance to proinsulin preventing disease whereas most antigens cannot, and also in human T1D based on proinsulin-specific T cells being found in the islets of affected individuals and the early appearance of insulin autoantibodies. Effective antigen-specific therapies that prevent T1D in humans have not yet been developed although doubt remains about the best molecular form of the antigen, the dose and the route of administration. Preclinical studies suggest that antigen specific therapy is most useful when administered before onset of autoimmunity but this time-window has not been tested in humans until the recent "pre-point" study. There may be a 'window of opportunity' during the neonatal period when 'vaccine' like administration of proinsulin for a short period may be sufficient to prevent diabetes. After the onset of autoimmunity, naive antigen-specific T cells have differentiated into antigen-experienced memory cells and the immune responses have spread to multiple antigens. Induction of tolerance at this stage becomes more difficult although recent studies have suggested generation of antigen-specific TR1 cells can inhibit memory T cells. Preclinical studies are required to identify additional 'help' that is required to induce tolerance to memory T cells and develop protocols for effective therapy in individuals with established autoimmunity.

Recent advances in type 1 diabetes

Type 1 diabetes (T1D) is caused by an autoimmune attack on pancreatic beta cells that leads to insulin deficiency. The incidence of T1D in Australia has doubled over the past 20 years. T1D treatment focuses on physiological insulin replacement, aiming for near-normal blood glucose levels. Hypoglycaemia is a significant cause of morbidity and mortality in T1D. Optimal T1D management is complex, and is enhanced by empowering individuals in all aspects of managing diabetes. New technologies, including insulin pumps, continuous glucose monitors and sensor-augmented pumps, can assist people achieve better glycaemic control and reduce the risk of severe hypoglycaemia. Women with T1D can achieve significantly better outcomes during pregnancy and for their infants by planning for their pregnancy and by intensive glycaemic control. Several trials are underway that seek to identify the determinants of autoimmunity and to develop therapies that prevent T1D in at-risk individuals. Pancreatic and islet cell transplants are proven therapies, but are only offered to individuals with diabetes and renal failure (pancreas) or severe hypoglycaemia unawareness (islet cell transplants). Although T1D is still associated with considerable premature mortality, recent findings show that a significant improvement in life expectancy has occurred.

Asthma, type 1 and type 2 diabetes mellitus, and inflammatory bowel disease amongst South Asian immigrants to Canada and their children: a population-based cohort study

BACKGROUND

There is a high and rising rate of immune-mediated diseases in the Western world. Immigrants from South Asia have been reported to be at higher risk upon arrival to the West. We determined the risk of immune-mediated diseases in South Asian and other immigrants to Ontario, Canada, and their Ontario-born children.

METHODS

Population-based cohorts of patients with asthma, type 1 diabetes (T1DM), type 2 diabetes (T2DM), and inflammatory bowel disease (IBD) were derived from health administrative data. We determined the standardized incidence, and the adjusted risk of these diseases in immigrants from South Asia, immigrants from other regions, compared with non-immigrant residents of Ontario. The risk of these diseases in the Ontario-born children of immigrants were compared to the children of non-immigrants.

RESULTS

Compared to non-immigrants, adults from South Asia had higher risk of asthma (IRR 1.56, 95%CI 1.51-1.61) and T2DM (IRR 2.59, 95%CI 2.53-2.65). Adults from South Asia had lower incidence of IBD than non-immigrants (IRR 0.32, 95%CI 0.22-0.49), as did immigrants from other regions (IRR 0.29, 95%CI 0.20-0.42). Compared to non-immigrant children, the incidence of asthma (IRR 0.66, 95%CI 0.62-0.71) and IBD (IRR 0.47, 95%CI 0.33-0.67) was low amongst immigrant children from South Asia. However, the risk in Ontario-born children of South Asian immigrants relative to the children of non-immigrants was higher for asthma (IRR 1.75, 95%CI 1.69-1.81) and less attenuated for IBD (IRR 0.90, 95%CI 0.65-1.22).

CONCLUSION

Early-life environmental exposures may trigger a genetic predisposition to the development of asthma and IBD in South Asian immigrants and their Canada-born children.

The intestinal microbiome in type 1 diabetes

Few concepts in recent years have garnered more disease research attention than that of the intestinal (i.e. 'gut') microbiome. This emerging interest has included investigations of the microbiome's role in the pathogenesis of a variety of autoimmune disorders, including type 1 diabetes (T1D). Indeed, a growing number of recent studies of patients with T1D or at varying levels of risk for this disease, as well as in animal models of the disorder, lend increasing support to the notion that alterations in the microbiome precede T1D onset. Herein, we review these investigations, examining the mechanisms by which the microbiome may influence T1D development and explore how multi-disciplinary analysis of the microbiome and the host immune response may provide novel biomarkers and therapeutic options for prevention of T1D.

Non-alcoholic fatty liver disease, diet and gut microbiota

Non-alcoholic fatty liver disease (NAFLD) is a severe liver disease that is increasing in prevalence with the worldwide epidemic of obesity and its related insulin-resistance state. Evidence for the role of the gut microbiota in energy storage and the subsequent development of obesity and some of its related diseases is now well established. More recently, a new role of gut microbiota has emerged in NAFLD. The gut microbiota is involved in gut permeability, low-grade inflammation and immune balance, it modulates dietary choline metabolism, regulates bile acid metabolism and produces endogenous ethanol. All of these factors are molecular mechanisms by which the microbiota can induce NAFLD or its progression toward overt non-alcoholic steatohepatitis. Modification of the gut microbiota composition and/or its biochemical capacity by specific dietary or pharmacological interventions may advantageously affect host metabolism. Large-scale intervention trials, investigating the potential benefit of prebiotics and probiotics in improving cardiometabolic health in high-risk populations, are fervently awaited.