Biology subjects

Dunger, D. B.

Publications and source records attributed to Dunger, D. B..

5 recordsLinked to original sources

bioRxiv2020

Fine-mapping, trans-ancestral and genomic analyses identify causal variants, cells, genes and drug targets for type 1 diabetes

We report the largest and most ancestrally diverse genetic study of type 1 diabetes (T1D) to date (61,427 participants), yielding 152 regions associated to false discovery rate < 0.01, including 36 regions associated to genome-wide significance for the first time. Credible sets of disease-associated variants are specifically enriched in immune cell accessible chromatin, particularly in CD4+ effector T cells. Colocalization with chromatin accessibility quantitative trait loci (QTL) in CD4+ T cells identified five regions where differences in T1D risk and chromatin accessibility are potentially driven by the same causal variant. Allele-specific chromatin accessibility further refined the set of putative causal variants with functional relevance in CD4+ T cells and integration of whole blood expression QTLs identified candidate T1D genes, providing high-yield targets for mechanistic follow-up. We highlight rs72938038 in BACH2 as a candidate causal T1D variant, where the T1D risk allele leads to decreased enhancer accessibility and BACH2 expression in T cells. Finally, we prioritise potential drug targets by integrating genetic evidence, functional genomic maps, and immune protein-protein interactions, identifying 12 genes implicated in T1D that have been targeted in clinical trials for autoimmune diseases. These findings provide an expanded genomic landscape for T1D, including proposed genetic regulatory mechanisms of T1D-associated variants and genetic support for therapeutic targets for immune intervention.

genetics↗

bioRxiv2019

Temporal Trends without Seasonal Effects on Gestational Diabetes Incidence Relate to Reductions in Indices of Insulin Secretion: The Cambridge Baby Growth Study

AimsThe incidence of gestational diabetes has been reported to have risen over the first decade of this century. Some studies have also found it to vary with seasons of the year. We therefore investigated temporal and seasonal trends on gestational diabetes incidence in a single centre cohort study from Cambridge, U.K., and attempted to explain trends using associations with risk factors. Materials and MethodsUsing a cosinor model we tested whether there were both temporal and seasonal trends in gestational diabetes incidence in 1,074 women recruited to the Cambridge Baby Growth Study in 2001-2009 who underwent oral glucose tolerance tests around week 28 of pregnancy. We also undertook risk factor analyses. ResultsThere was a temporal increase in gestational diabetes incidence over the course of recruitment to this study (p=2.1x10-3) but no seasonal effect (p=0.7). HOMA B (p=3.0x10-3; n=1,049) and the insulin disposition index (p=3.0x10-3; n=1,000) showed negative temporal trends. There was no negative association with HOMA S. Risk factor analyses showed a concomitant temporal slight increase in the index of multiple deprivation (p=4.6x10-10, n=1,068). This index was positively associated with HOMA B (p=6.1x10-5, n=955) but not directly with gestational diabetes (p=0.6, n=1,032), HOMA S (p=0.2, n=955) or the insulin disposition index (p=0.4, n=955). ConclusionsIn this population there were temporal but not seasonal increases in gestational diabetes incidence between the years 2001 and 2009, which appeared to be related more to reductions in insulin secretion than sensitivity. Possible mediators of this link include confounding factors related to deprivation.

epidemiology↗

bioRxiv2018

Frequent Monitoring of C-peptide Levels in Newly Diagnosed Type 1 Subjects Using Dried Blood Spots Collected at Home

ObjectiveTo evaluate a novel approach to measure {beta}-cell function by frequent testing of C-peptide concentrations in dried blood spots (DBS)\n\nPatientsThirty-two children, aged 7-17 years, recently diagnosed with type 1 diabetes.\n\nDesignMixed-meal-tolerance-test (MMTT) within 6 and again 12 months after diagnosis with paired venous and DBS C-peptide sampling at 0 and 90 minutes. Weekly DBS C-peptide before and after standardized breakfasts collected at home.\n\nResultsDBS and plasma C-peptide levels (n=115) correlated strongly (r=0{middle dot}91; p<0.001). The Bland-Altman plot indicated good agreement. The median number of home-collected DBS cards per participant was 24 over a median of 6.9 months. Repeated DBS C-peptide levels varied considerably within and between subjects. Adjustment for corresponding home glucose measurements reduced the variance permitting accurate description of changes over time. The correlation of the C-peptide slope over time assessed by repeated home DBS versus area under the curve during the two MMTTs was r=0{middle dot}73; p<0.001. Mixed models showed that a 1-month increase of diabetes duration was associated with 17 pmol/l decline in fasting DBS C-peptide, whereas increases of 1 mmol/l in glucose, 1 year older age-at-diagnosis and 100 pmol/l higher baseline plasma C-peptide were associated with 18, 17 and 61 pmol/l higher fasting DBS C-peptide levels, respectively. In addition, glucose responsiveness decreased with longer diabetes duration.\n\nConclusionOur approach permitted frequent assessment of C-peptide, making it feasible to monitor {beta}-cell function at home. Evaluation of changes in the slope of C-peptide using this method may permit short-term evaluation of promising interventions.

biochemistry↗

bioRxiv2017

GDF15 Concentrations in Maternal Serum Associated with Vomiting in Pregnancy: the Cambridge Baby Growth Study

Nausea and vomiting in pregnancy (NVP) affects 70-90% of all pregnant women but its pathogenesis is unknown. Growth and Differentiation Factor 15 (GDF15), secreted from the trophoblast and decidual stromal cells, is present at high levels in the blood of pregnant women. The receptor for GDF15 has recently been identified and is specifically expressed in the hindbrain where it transmits aversive signals including nausea and conditioned taste aversion. We explored the relationship between GDF15 concentrations in maternal serum during pregnancy and self-reported NVP. In a study of 791 women from the Cambridge Baby Growth Study maternal GDF15 concentrations were higher in women who reported vomiting in the 2nd trimester (geometric mean: 11,670 pg/mL; 95% confidence interval: 11,056-12,318) and were even higher in the eleven women who reported taking anti-emetics during pregnancy (13,376 (10,821-16,535) compared to those who reported no nausea or vomiting during pregnancy (10,657 (10,121-11,222); P=0.02 and P=0.04, respectively, adjusted for gestational age at sampling and maternal BMI). In conclusion serum GDF15 concentrations early in the second trimester of pregnancy are significantly and positively associated with second trimester vomiting and with maternal anti-emetic use. In the context of the recently revealed biology of GDF15 this data suggests that antagonism of GDF15 may have some potential for therapeutic benefit in NVP.

developmental biology↗

bioRxiv2017

Cells With Treg-Specific FOXP3 Demethylation But Low CD25 Are Prevalent In Autoimmunity

Identification of alterations in the cellular composition of the human immune system is key to understanding the autoimmune process. Recently, a subset of FOXP3+ cells with low CD25 expression was found to be increased in peripheral blood from systemic lupus erythematosus (SLE) patients, although its functional significance remains controversial. Here we find in comparisons with healthy donors that the frequency of FOXP3+ cells within CD127lowCD25low CD4+ T cells (here defined as CD25lowFOXP3+ T cells) is increased in patients affected by autoimmune disease of varying severity, from combined immunodeficiency with active autoimmunity, SLE to type 1 diabetes. We show that CD25lowFOXP3+ T cells share phenotypic features resembling conventional CD127lowCD25highFOXP3+ Tregs, including demethylation of the Treg-specific epigenetic control region in FOXP3 that is highly enriched in HELIOS+ cells, and lack of IL-2 production. As compared to conventional Tregs, more CD25lowFOXP3+HELIOS+ T cells are in cell cycle (33.0% vs 20.7% Ki-67+; P = 1.3 x 10-9) and express the late-stage inhibitory receptor PD-1 (67.2% vs 35.5%; P = 4.0 x 10-18), while having reduced expression of the early-stage inhibitory receptor CTLA-4, as well as other Treg markers, such as FOXP3 and CD15s. The number of CD25lowFOXP3+ T cells are highly correlated (P = 1.2 x 10-19) with the proportion of CD25highFOXP3+ T cells in cell cycle (Ki-67+). These findings suggest that CD25lowFOXP3+ T cells represent a subset of Tregs that are derived from CD25highFOXP3+ T cells, and are a peripheral marker of recent Treg expansion in response to an autoimmune reaction in tissues.\n\nHighlights- FOXP3+ compartment within CD127lowCD25low T cells is expanded in autoimmune patients.\n\n- Increased numbers of CD25lowFOXP3+ T cells are a circulating marker of autoimmunity.\n\n- CD25lowFOXP3+ HELIOS+ T cells are fully demethylated at the FOXP3 TSDR.\n\n- CD25lowFOXP3+ T cells could represent a terminal stage of regulatory T cells.

immunology↗