No long-term effects of antenatal synthetic glucocorticoid exposure on epigenetic regulation of stress-related genes

Abstract

Antenatal synthetic glucocorticoid (sGC) treatment is a potent modifier of the hypothalamic-pituitary-adrenal (HPA) axis. In this context, epigenetic modifications are discussed as potential regulators explaining how prenatal exposure to GCs might translate into persistent changes of HPA axis "functioning". The purpose of this study was to investigate whether DNA methylation and gene expression profiles of stress-associated genes (NR3C1; FKBP5; SLC6A4) may mediate the persistent effects of sGC on cortisol stress reactivity that have been previously observed. In addition, hair cortisol concentrations (hairC) were investigated as a valid biomarker of long-term HPA axis activity. This cross-sectional study comprised 108 term-born children and adolescents, including individuals with antenatal GC treatment and controls. From whole blood, DNA methylation was analyzed by targeted deep bisulfite sequencing. Relative mRNA expression was determined by RT-qPCR experiments and qBase analysis. Acute stress reactivity was assessed by the Trier Social Stress Test (TSST) measuring salivary cortisol by ELISA and hairC concentrations were determined from hair samples by liquid chromatography coupled with tandem mass spectrometry. First, no differences in DNA methylation and mRNA expression levels of the stress-associated genes between individuals treated with antenatal sGC compared to controls were found. Second, DNA methylation and mRNA expression levels were neither associated with cortisol stress reactivity nor with hairC. These findings do not corroborate the belief that DNA methylation and mRNA expression profiles of stress-associated genes (NR3C1; FKBP5; SLC6A4) play a key mediating role of the persistent effects of sGC on HPA axis functioning.

Fig. 1. Effects of antenatal sGC treatment on DNA methylation and mRNA expression.

Upper part: There were no significant differences in mean DNA methylation levels between the three groups (pathological pregnancy group with antenatal synthetic glucocorticoid treatment (PP/GC), pathological pregnancy group without antenatal synthetic glucocorticoid treatment (PP/non-GC), untreated control group from physiological pregnancies). Data show mean with 95% confidence interval. A Mean DNA methylation of FKBP5. B Mean DNA methylation of SLC6A4. Lower part: There were no significant differences in mRNA expression levels between the three groups. C mRNA expression of FKBP5. D mRNA expression of SLC6A4. E mRNA expression of NR3C1.

Fig. 2. Association of DNA methylation and mRNA expression with cortisol stress reactivity.

Upper part: Mean DNA methylation levels were not significantly related to cortisol stress reactivity (indexed by the cortisol AUCi). A Mean DNA methylation of FKBP5. B Mean DNA methylation of SLC6A4. Lower part: mRNA expression levels were not significantly related to cortisol stress reactivity. C mRNA expression of FKBP5. D mRNA expression of SLC6A4. E mRNA expression of NR3C1.

Fig. 3. Association of DNA methylation and mRNA expression with hairC.

Upper part: Mean DNA methylation levels were not significantly related to hair cortisol concentration (hairC). A Mean DNA methylation of FKBP5. B Mean DNA methylation of SLC6A4. Lower part: mRNA expression levels were not significantly related to hairC. C mRNA expression of FKBP5. D mRNA expression of SLC6A4. E mRNA expression of NR3C1.