Differential adipokine DNA methylation and gene expression in subcutaneous adipose tissue from adult offspring of women with diabetes in pregnancy

Research Open Access Differential adipokine DNA methylation and gene expression in subcutaneous adipose tissue from adult offspring of women with diabetes in pregnancy Azadeh Houshmand-Oeregaard1, 2, 3Email author, Ninna S. Hansen2, 3, 4, Line Hjort2, 3, 4, Louise Kelstrup1, 3, Christa Broholm2, Elisabeth R. Mathiesen1, 3, 5, Tine D. Clausen3, 6, Peter Damm1, 3 and Allan Vaag2, 3, 7 Clinical EpigeneticsThe official journal of the Clinical Epigenetics Society20179:37 https://doi.org/10.1186/s13148-017-0338-2 ©  The Author(s). 2017 Received: 29 October 2016Accepted: 31 March 2017Published: 13 April 2017 Abstract Background Offspring of women with diabetes in pregnancy are at increased risk of type 2 diabetes mellitus (T2DM), potentially mediated by epigenetic mechanisms. The adipokines leptin, adiponectin, and resistin (genes: LEP, ADIPOQ, RETN) play key roles in the pathophysiology of T2DM. We hypothesized that offspring exposed to maternal diabetes exhibit alterations in epigenetic regulation of subcutaneous adipose tissue (SAT) adipokine transcription. We studied adipokine plasma levels, SAT gene expression, and DNA methylation of LEP, ADIPOQ, and RETN in adult offspring of women with gestational diabetes (O-GDM, N = 82) or type 1 diabetes (O-T1DM, N = 67) in pregnancy, compared to offspring of women from the background population (O-BP, N = 57). Results Compared to O-BP, we found elevated plasma leptin and resistin levels in O-T1DM, decreased gene expression of all adipokines in O-GDM, decreased RETN expression in O-T1DM, and increased LEP and ADIPOQ methylation in O-GDM. In multivariate regression analysis, O-GDM remained associated with increased ADIPOQ methylation and decreased ADIPOQ and RETN gene expression and O-T1DM remained associated with decreased RETN expression after adjustment for potential confounders and mediators. Conclusions In conclusion, offspring of women with diabetes in pregnancy exhibit increased ADIPOQ DNA methylation and decreased ADIPOQ and RETN gene expression in SAT. However, altered methylation and expression levels were not reflected in plasma protein levels, and the functional implications of these findings remain uncertain. Keywords EpigeneticsMethylationDiabetesPregnancyGestational diabetesFetal programming Background Early-life exposures may cause persisting changes in offspring metabolism, a concept known as fetal programming [1–3]. Offspring of women with diabetes in pregnancy have an increased risk of obesity, metabolic syndrome, and type 2 diabetes mellitus (T2DM) [1, 2, 4–6]. The risk appears higher than can be explained by genetics [7, 8], implicating a key role for the intrauterine environment. The molecular mechanisms underlying transmission of diabetes risk from mother to offspring are unknown, but may involve modulation of circulating adipokines, which are hormones secreted by adipose tissue. Leptin (gene: LEP), adiponectin (gene: ADIPOQ), and resistin (gene: RETN) are candidate adipokines for investigation of metabolic diseases, as all three are involved in regulation of metabolism, appetite, and insulin sensitivity [9]. High leptin levels are associated with obesity, insulin resistance, and metabolic syndrome, and conversely elevated plasma adiponectin levels are associated with decreased risk of T2DM [10, 11], while associations for resistin are contradictory [11–14]. The changes in offspring metabolism induced by exposure to a detrimental fetal environment are thought to be mediated partly by epigenetic mechanisms, with DNA methylation being the best understood of these mechanisms [15]. Targeted and global epigenetic changes, including changes in methylation of genes encoding adipokines, have been reported in placenta (a central organ in the flux of nutrition from mother to fetus, important for mediating the impact of maternal GDM) and cord blood from newborn offspring in response to prenatal exposure to maternal obesity, hyperglycemia, and GDM [16–27], but the extent to which these changes persist into adulthood is unknown. Studies of the association between maternal glycemia or BMI and offspring adipokine methylation have rendered contradictory results, showing decreased LEP and ADIPOQ methylation on the fetal side of the placenta with increasing maternal blood glucose concentrations [17, 18] or increased placental LEP DNA methylation with exposure to gestational diabetes mellitus (GDM) and maternal obesity [23]. Results on RETN methylation are lacking, as are studies of adipokine methylation in adulthood. The aim of our study was to investigate whether exposure to maternal diabetes causes changes in methylation and gene expression in these adipokines, with corresponding changes in plasma levels, and thereby to test the hypothesis that epigenetic mechanisms controlling adipokine gene expression and secretion are involved in the fetal programming of T2DM. We measured adipokine plasma levels, gene expression, and DNA methylation in subcutaneous adipose tissue (SAT) in a unique cohort of adult offspring of women with either GDM or type 1 diabetes mellitus (T1DM) in pregnancy, compared to control offspring of women from the background population. Methods Study design The study was an observational follow-up of adult offspring of women with diabetes. Details of the study design, maternal inclusion criteria. and baseline data have been described previously [5, 6, 28]. The original cohort consisted of 1066 adult offspring born between 1978 and 1985 at Rigshospitalet, Denmark. All offspring born to women with either GDM or T1DM, or to women from the background population in this period, were invited (Fig. 1). The participants in this study were between 26 and 35 years old. Of the 597 eligible offspring from the first cross-sectional study, 456 were eligible for participation in this round of follow-up. Fig. 1 Study design—flowchart of subjects participating and lost to follow-up. O-GDM offspring of women with gestational diabetes in pregnancy, O-NoGDM offspring of women with risk factors for gestational diabetes but normal glucose tolerance in pregnancy, O-T1DM offspring of women with type 1 diabetes in pregnancy, O-BP offspring of women from the background population. *In the original cohort, 812 offspring were from the three groups, O-GDM, O-T1DM, and O-BP, due to the fact that O-NoGDM (n = 254) were not invited for the second follow-up (1066 − 254 = 812) Participants belonged to one of three groups depending on exposure to maternal diabetes: offspring of women with diet-treated gestational diabetes (O-GDM, N = 82), offspring of women with type 1 diabetes (O-T1DM, N = 67), and offspring of women from the background population (O-BP, N = 57). Of the 456 eligible offspring from the second follow-up, a total of 45% (49% O-GDM, 42% O-T1DM, and 45% O-BP) participated in this round of follow-up, and there was no inter-group difference in participation rate (p = 0.445). (...truncated)