The cardiovascular and hypothalamus-pituitary-adrenal axis response to stress is controlled by glucocorticoid receptor sequence variants and promoter methylation

The relationship between self-reported chronic stress, physiological stress axis dysregulation and medically-unexplained symptoms

The positive feedback model of medically-unexplained symptoms posits that chronic stress affects the activity of the physiological stress axes, which in turn generates medically-unexplained symptoms. As a first step to empirically test its model assumptions, we investigated potential associations between chronic stress, physiological stress axis activity and medically-unexplained in a cross-sectional study. One hundred-ninety-nine healthy individuals provided self-reports on chronic stress and medically-unexplained symptoms, resting heart rate/variability (HR/HRV; e.g., root mean square of successive differences/RMSSD, low frequency/LF power), cortisol awakening response (CAR) and diurnal cortisol. Significant positive contributors to medically-unexplained symptoms were the chronic stress scales 'lack of social appreciation' and 'chronic worries', as well as CAR and LF HRV; diurnal cortisol was a negative contributor. Mediation analyses showed that the impact of neural indicators associated with physiological stress axis activity (HR/HRV) related to medically-unexplained symptoms, which was mediated by chronic stress, whereas the mediation effect as suggested by the positive feedback model was not significant. These cross-sectional findings do not support the positive feedback model. Longitudinal studies are required to conclude about potential mechanistic and causal relationships in the model. Nevertheless, our mediation analyses give first indication that the constitution of physiological stress axes may play a major role in how stressors are perceived and which kind of health-consequences (e.g., medically-unexplained symptoms) this may have.

Glucocorticoid Receptor Gene (NR3C1) Polymorphisms and Metabolic Syndrome: Insights from the Mennonite Population

The regulation of the hypothalamic-pituitary-adrenal (HPA) axis is associated with polymorphisms and the methylation degree of the glucocorticoid receptor gene (NR3C1) and is potentially involved in the development of metabolic syndrome (MetS). In order to evaluate the association between MetS with the polymorphisms, methylation, and gene expression of the NR3C1 in the genetically isolated Brazilian Mennonite population, we genotyped 20 NR3C1 polymorphisms in 74 affected (MetS) and 138 unaffected individuals without affected first-degree relatives (Co), using exome sequencing, as well as five variants from non-exonic regions, in 70 MetS and 166 Co, using mass spectrometry. The methylation levels of 11 1F CpG sites were quantified using pyrosequencing (66 MetS and 141 Co), and the NR3C1 expression was evaluated via RT-qPCR (14 MetS and 25 Co). Age, physical activity, and family environment during childhood were associated with MetS. Susceptibility to MetS, independent of these factors, was associated with homozygosity for rs10482605*C (OR = 4.74, pcorr = 0.024) and the haplotype containing TTCGTTGATT (rs3806855*T_ rs3806854*T_rs10482605*C_rs10482614*G_rs6188*T_rs258813*T_rs33944801*G_rs34176759*A_rs17209258*T_rs6196*T, OR = 4.74, pcorr = 0.048), as well as for the CCT haplotype (rs41423247*C_ rs6877893*C_rs258763*T), OR = 6.02, pcorr = 0.030), but not to the differences in methylation or gene expression. Thus, NR3C1 polymorphisms seem to modulate the susceptibility to MetS in Mennonites, independently of lifestyle and early childhood events, and their role seems to be unrelated to DNA methylation and gene expression.

How can early life adversity still exert an effect decades later? A question of timing, tissues and mechanisms

Exposure to any number of stressors during the first 1000 days from conception to age 2 years is important in shaping an individual's life trajectory of health and disease. Despite the expanding range of stressors as well as later-life phenotypes and outcomes, the underlying molecular mechanisms remain unclear. Our previous data strongly suggests that early-life exposure to a stressor reduces the capacity of the immune system to generate subsequent generations of naïve cells, while others have shown that, early life stress impairs the capacity of neuronal stem cells to proliferate as they age. This leads us to the "stem cell hypothesis" whereby exposure to adversity during a sensitive period acts through a common mechanism in all the cell types by programming the tissue resident progenitor cells. Furthermore, we review the mechanistic differences observed in fully differentiated cells and suggest that early life adversity (ELA) may alter mitochondria in stem cells. This may consequently alter the destiny of these cells, producing the lifelong "supply" of functionally altered fully differentiated cells.

Mild daily stress, in interaction with NR3C1 DNA methylation levels, is linked to alterations in the HPA axis and ANS response to acute stress in early adolescents

BACKGROUND

Daily Hassles (DH) or daily stress - is a mild type of stressor with unique contributions to psychological distress. Yet, most prior studies that investigate the effects of stressful life experiences focus on childhood trauma or on early life stress and little is known about the effects of DH on epigenetic changes in stress system related genes and on the physiological response to social stressors.

METHODS

In the present study, conducted among 101 early adolescents (mean age = 11.61; SD = 0.64), we investigated whether Autonomic Nervous System (ANS) (namely heart rate and heart rate variability) and Hypothalamic-Pituitary-Adrenal (HPA) axis functioning (measured as cortisol stress reactivity and recovery) are associated with DNA methylation (DNAm) in the glucocorticoid receptor gene (NR3C1), the level of DH and their interaction. To assess the stress system functioning the TSST protocol was used.

RESULTS

Our findings show that higher NR3C1 DNAm in interaction with higher levels of daily hassles, is associated with blunted HPA axis reactivity to psychosocial stress. In addition, higher levels of DH are associated with extended HPA axis stress recovery. In addition, participants with higher NR3C1 DNAm had lower ANS adaptability to stress, specifically lower parasympathetic withdrawal; for heart rate variability this effect was strongest for participants with higher level of DH.

CONCLUSIONS

The observation that interaction effects between NR3C1 DNAm levels and daily stress on the functioning of the stress-systems, are already detectable in young adolescents, highlights the importance of early interventions, not only in the case of trauma, but also daily stress. This might help to prevent stress-induced mental and physical disorders later in life.

Effects of prenatal exposure to the 1944-45 Dutch famine and glucocorticoid receptor polymorphisms on later life PTSD susceptibility

Background: Exposure to adversity in utero is thought to increase susceptibility to develop posttraumatic stress disorder (PTSD) following later life trauma, due to neurobiological programming effects during critical developmental periods. It remains unknown whether effects of prenatal adversity on PTSD susceptibility are modulated by genetic variations in neurobiological pathways implicated in PTSD susceptibility.Objective: We investigated whether genetic variation in the glucocorticoid receptor (GR) modulated effects of prenatal famine exposure on late adulthood PTSD symptom severity after trauma exposure in childhood and mid-to-late adulthood.Method: We included N = 439 term-born singleton adults (mean age: 72 years, 54.2% women) from the Dutch Famine Birth Cohort, born around the time of the Dutch Famine of 1944/1945, divided into exposure and control groups based on timing of the famine during gestation. Participants filled out self-report questionnaires on childhood (Childhood Trauma Questionnaire) and mid-to-late adulthood (Life Events Checklist for DSM-5) trauma, and current PTSD symptom severity (PTSD Checklist for DSM-5). GR haplotypes were determined from four functional GR single nucleotide polymorphisms (ER22/23EK, N363S, BclI and exon 9β) in previously collected DNA. Linear regression analyses were performed to investigate associations of GR haplotype and prenatal famine exposure in conjunction with later life trauma on PTSD symptom severity.Results: We observed a significant three-way interaction between the GR Bcll haplotype, famine exposure during early gestation, and adulthood trauma exposure on PTSD symptom severity in late adulthood. Only participants exposed to famine during early gestation without the GR Bcll haplotype showed a significantly stronger positive association between adulthood trauma and PTSD symptom severity than non-exposed participants, indicating increased PTSD susceptibility.Conclusions: Our results illustrate the importance of integrated approaches considering genetics and environmental contexts throughout various life periods, including the rarely investigated prenatal environment, to elucidate how PTSD susceptibility evolves throughout life.HIGHLIGHTS Adversity during pregnancy is thought to increase offspring's PTSD risk following later life trauma, but exact neurobiological mechanisms underlying this process remain unknown.We found that effects of prenatal famine exposure on PTSD symptom severity were influenced by genetic variation in the glucocorticoid receptor, which signals effects of the stress hormone cortisol.Integrated approaches considering genetics and environmental contexts throughout both early and later life are important to understand how PTSD risk evolves throughout life.

The interplay between DNA methylation and cardiac autonomic system functioning: a systematic review

Epigenetic marks, particularly DNA methylation (DNAm), are emerging as an important biological marker of susceptibility to cardiac autonomic dysfunction. This review summarizes recent discoveries about the association between DNAm and cardiac autonomic activity. A systematic literature search was performed through the Embase, Web of Science, Cochrane Library, Pubmed, PsycINFO, and Pilots databases. Twenty-two studies met inclusion criteria, of which 18 were human studies including a total of 2,686 participants. DNAm differences in multiple genes, such as NR3C1, TLR2, GPR133, EPO, PHGDH, OXTR, and SLC7A11, linked environmental stressors to physiological responses. For instance, exposure to psychosocial stressors increased NR3C1 methylation, which was associated with both decreased blood pressure and increased parasympathetic activity. Additionally, GPR133 played a potential role in cardiac autonomic dysfunction in an occupational setting, affecting the heart rate's deceleration capacity in welders. This review's findings suggest that DNAm is involved in cardiac autonomic regulation under different stress-mediated responses.

Genetic variability in exon 1 of the glucocorticoid receptor gene NR3C1 is associated with postoperative complications

Patients undergoing major surgery experience postoperative inflammation, which may contribute to postoperative morbidity. Endogenous glucocorticoids (GCs) are an essential part of the stress response, but this response varies between individuals, which may in turn affect clinical outcome and specifically postoperative inflammation. Exon 1 of the NR3C1 gene, encoding the GC receptor (GR), contains an established region of differential regulation. DNA methylation patterns in this region have been found to differ between individuals. The present study investigated the methylation status and genotype in the cytosine‑phosphate‑guanine (CpG) island in exon 1 of NR3C1 in 24 patients [Median age 65.5 (range 42‑81) years, 11 male, 13 female] who underwent major abdominal (12 pancreatic, 12 hepatic) surgery and explored its association with postoperative complications. DNA was extracted from peripheral blood leukocytes and underwent targeted bisulfite sequencing of the CpG island. Complications were graded according to the Clavien‑Dindo classification and 14 out of 24 patients had postoperative complications. Multifactorial and partial least square analyses were used to analyse the data. A homogenous demethylated pattern was observed in all patients and no single CpG methylation was associated with postoperative complications. Four SNPs were significantly associated with higher Clavien‑Dindo scores. Genetic variability in the chromosome 5:143,402,505‑143,405,805 region of exon 1 of the GR gene NR3C1, but not DNA methylation, was associated with more severe postoperative complications in patients having major abdominal surgery. These results indicated that the patients' response to GCs may be of clinical importance for inflammatory conditions.

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

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.

REVEALING THE MOLECULAR-GENETIC AND CLINICAL PREDICTORS OF GLUCOCORTICOID RESISTANCE IN PATIENTS WITH HAND ECZEMA

OBJECTIVE

The aim: To reveal the possible predictors of the glucocorticoid resistance in patients with hand eczema (HE) based on the demographic, clinical, and molecular-genetic data.

PATIENTS AND METHODS

Materials and methods: 143 patients with HE were included in the study. Demographic, clinical, biochemical (blood content of IgE, IL-17A, IL-2, 25(OH)D), and genetic (rs41423247 genotypes) data were obtained from all patients.

RESULTS

Results: After 2 weeks of treatment by glucocorticoids, all subjects were divided into "responder" and "non-responder" groups according to change of the Hand Eczema Severity Index (HECSI). Statistical analysis was done using SPSS (version 22.0.). Binary logistic regression was used to identify predictors of glucocorticoid resistance. P-value 0.05). The results of the multivariate regression showed that Bcl-1 G-allele (OR =3.83; P = 0.033), and severe eczema (OR = 2.52; P = 0.023) are linked with an elevated risk of glucocorticoid resistance in patients with hand eczema.

CONCLUSION

Conclusions: Insensitivity to glucocorticoids in HE patients is associated with NR3C1 gene Bcl-1 polymorphism, eczema severity and blood level of IL-17, IL-2, 25(OH)D. The final adjustment showed that minor C-allele of the Bcl-1 polymorphism and severe eczema are the strongest predictors of the glucocorticoid resistance.

Glucocorticoid receptor signaling in leukocytes after early life adversity

Early life adversity (ELA) has been associated with inflammation and immunosenescence, as well as hyporeactivity of the HPA axis. Because the immune system and the HPA axis are tightly intertwined around the glucocorticoid receptor (GR), we examined peripheral GR functionality in the EpiPath cohort among participants who either had been exposed to ELA (separation from parents and/or institutionalization followed by adoption; n = 40) or had been reared by their biological parents (n = 72).Expression of the strict GR target genes FKBP5 and GILZ as well as total and 1F and 1H GR transcripts were similar between groups. Furthermore, there were no differences in GR sensitivity, examined by the effects of dexamethasone on IL6 production in LPS-stimulated whole blood. Although we did not find differences in methylation at the GR 1F exon or promoter region, we identified a region of the GR 1H promoter (CpG 1-9) that showed lower methylation levels in ELA.Our results suggest that peripheral GR signaling was unperturbed in our cohort and the observed immune phenotype does not appear to be secondary to an altered GR response to the perturbed HPA axis and glucocorticoid (GC) profile, although we are limited in our measures of GR activity and time points.

Stress & executive functioning: A review considering moderating factors

A multitude of studies investigating the effects of stress on cognition has produced an inconsistent picture on whether - and under which conditions - stress has advantageous or disadvantageous effects on executive functions (EF). This review provides a short introduction to the concept of stress and its neurobiology, before discussing the need to consider moderating factors in the association between stress and EF. Three core domains are described and discussed in relation to the interplay between stress and cognition: the influence of different paradigms on physiological stress reactivity, individual differences in demographic and biological factors, and task-related features of cognitive tasks. Although some moderating variables such as the endocrine stress response have frequently been considered in single studies, no attempt of a holistic overview has been made so far. Therefore, we propose a more nuanced and systematic framework to study the effects of stress on executive functioning, comprising a holistic overview from the induction of stress, via biological mechanisms and interactions with individual differences, to the influence of stress on cognitive performance.

Higher perceived stress is associated with lower cortisol concentrations but higher salivary interleukin-1beta in socially evaluated cold pressor test

The relationship between subjective stress perception and the objective stress response to acute stress stimuli is not sufficiently understood. The aim of the present study was to test the hypothesis that the neuroendocrine response in socially evaluated cold pressor test (CPT) depends on the extent of perceived stressfulness of the stimulus. The test was performed in 24 healthy male volunteers. Subjective stress perception was assessed using nine visual analog scales. The subjects were divided to low and high stress perception groups according to the median split of the scores. Subjects with high stress perception exhibited slightly lower values of systolic blood pressure and lower overall concentrations of salivary cortisol compared to subjects with low stress perception. Salivary alpha-amylase activity did not show significant changes. Salivary aldosterone decreased in time in subjects with low but increased early after the test in subjects with high stress perception. Interestingly, salivary concentrations of the pro-inflammatory cytokine interleukin-1beta were considerably higher in subjects with high stress perception, particularly immediately before the test. The differences in salivary cortisol and interleukin-1beta were confirmed by the analysis with distress as a continuous covariate. Distress scores correlated negatively with salivary cortisol and positively with interleukin-1beta. The rate pressure product, which is a global measure of energy consumption by the heart, was significantly higher immediately before than after the stress exposure. The present findings show that concentrations of interleukin-1beta are a sensitive component of the stress response at the time before the stressful event.Lay summaryIt is generally expected that higher perceived stressfulness of a stimulus is accompanied by higher activation of stress-related systems. This study evaluating a combined psychosocial and physical stress situation in healthy men provides evidence that individual parameters of the stress response are differently related to perceived stress intensity. Subjects with high stress perception exhibited lower systolic blood pressure and salivary cortisol, higher interleukin-1beta, marginal differences in alpha amylase and aldosterone compared to subjects with low stress perception, which might be important for stress coping.

Fetal programming in dairy cows: Effect of heat stress on progeny fertility and associations with the hypothalamic-pituitary-adrenal axis functions

Ambient temperatures that result in body temperatures beyond those of the thermo-neutral zone for dairy cattle can lead to reduced reproductive efficiencies that have negative effects on economic and productive efficiencies of dairy farms. In addition, in pregnant cows, ambient temperature-induced heat stress leads to modifications in the epigenome of the developing embryo, which, in turn, could lead to phenotypic variations in the sexually mature animal and its offspring. In the mammalian response to stress, adrenocorticotropic hormone stimulates the synthesis and secretion of glucocorticoids, which may have detrimental effects on the hypothalamic-pituitary-gonadal axis and the female estrous cycle. The aim of this review is to describe the effects of ambient heat stress on the reproductive system of dairy cattle and its potential trans-generational effects. There are many heat stress occurrences in dairy cattle during a large portion of the year in many countries and there is an increase in incidence with the onset of global warming. These heat stress conditions make it possible that the embryo/fetus of cows may be affected when heat stress conditions prevail in ways that there is impaired fertility of the sexually mature cows that develop from these embryos/fetuses. This is the outcome because of molecular changes in ovarian glucocorticoid response caused by epigenetic modifications established during fetal development.

Synergistic effects of depression and NR3C1 methylation on prognosis of acute coronary syndrome

High levels of methylation in the GR gene (nuclear receptor subfamily 3, group C, member 1; NR3C1) have been associated with depression and cardiovascular risk. This study aimed to investigate whether NR3C1 methylation status was associated with the long-term prognosis of acute coronary syndrome (ACS) considering depression and cardiovascular status at the early phase of ACS. A total of 969 patients with recent ACS were recruited at a tertiary university hospital in Korea. Baseline evaluations were made from 2007 to 2012, including DSM-IV depressive disorder, NR3C1 methylation, and various demographic and clinical characteristics such as cardiovascular risk markers. Over a 5~12 year follow-up after the index ACS, time to major adverse cardiac event (MACE) was investigated using Cox regression models. Higher NR3C1 methylation status was associated with depression and several cardiovascular risk markers at baseline. NR3C1 hypermethylation predicted worse long-term prognosis of ACS only in the presence of depressive disorder with significant synergistic interaction terms and independent of potential confounding factors. Synergistic effects of depressive disorder and NR3C1 hypermethylation on long-term cardiac outcomes in ACS were found. NR3C1 methylation status represents a candidate prognostic biomarker for ACS in combination with a diagnosis of depressive disorder. Further research is needed to ascertain the generalisability of these findings.

Contribution of DNA methylation in chronic stress-induced cardiac remodeling and arrhythmias in mice

It is recognized that stress can induce cardiac dysfunction, but the underlying mechanisms are not well understood. The present study aimed to test the hypothesis that chronic negative stress leads to alterations in DNA methylation of certain cardiac genes, which in turn contribute to pathologic remodeling of the heart. We found that mice that were exposed to chronic restraint stress (CRS) for 4 wk exhibited cardiac remodeling toward heart failure, as characterized by ventricular chamber dilatation, wall thinning, and decreased contractility. CRS also induced cardiac arrhythmias, including intermittent sinus tachycardia and bradycardia, frequent premature ventricular contraction, and sporadic atrioventricular conduction block. Circulating levels of stress hormones were elevated, and the cardiac expression of tyrosine hydroxylase, a marker of sympathetic innervation, was increased in CRS mice. Using reduced representation bisulfite sequencing, we found that although CRS did not lead to global changes in DNA methylation in the murine heart, it nevertheless altered methylation at specific genes that are associated with the dilated cardiomyopathy (DCM) (e.g., desmin) and adrenergic signaling of cardiomyocytes (ASPC) (e.g., adrenergic receptor-α1) pathways. We conclude that CRS induces cardiac remodeling and arrhythmias, potentially through altered methylation of myocardial genes associated with the DCM and ASPC pathways.-Zhang, P., Li, T., Liu, Y.-Q., Zhang, H., Xue, S.-M., Li, G., Cheng, H.-Y.M., Cao, J.-M. Contribution of DNA methylation in chronic stress-induced cardiac remodeling and arrhythmias in mice.

Socioeconomic Deprivation, Adverse Childhood Experiences and Medical Disorders in Adulthood: Mechanisms and Associations

Severe socioeconomic deprivation (SED) and adverse childhood experiences (ACE) are significantly associated with the development in adulthood of (i) enhanced inflammatory status and/or hypothalamic-pituitary-adrenal (HPA) axis dysfunction and (ii) neurological, neuroprogressive, inflammatory and autoimmune diseases. The mechanisms by which these associations take place are detailed. The two sets of consequences are themselves strongly associated, with the first set likely contributing to the second. Mechanisms enabling bidirectional communication between the immune system and the brain are described, including complex signalling pathways facilitated by factors at the level of immune cells. Also detailed are mechanisms underpinning the association between SED, ACE and the genesis of peripheral inflammation, including epigenetic changes to immune system-related gene expression. The duration and magnitude of inflammatory responses can be influenced by genetic factors, including single nucleotide polymorphisms, and by epigenetic factors, whereby pro-inflammatory cytokines, reactive oxygen species, reactive nitrogen species and nuclear factor-κB affect gene DNA methylation and histone acetylation and also induce several microRNAs including miR-155, miR-181b-1 and miR-146a. Adult HPA axis activity is regulated by (i) genetic factors, such as glucocorticoid receptor polymorphisms; (ii) epigenetic factors affecting glucocorticoid receptor function or expression, including the methylation status of alternative promoter regions of NR3C1 and the methylation of FKBP5 and HSD11β2; (iii) chronic inflammation and chronic nitrosative and oxidative stress. Finally, it is shown how severe psychological stress adversely affects mitochondrial structure and functioning and is associated with changes in brain mitochondrial DNA copy number and transcription; mitochondria can act as couriers of childhood stress into adulthood.

Methylation of the glucocorticoid receptor gene associated with depression in patients with acute coronary syndrome

OBJECTIVE

The present study investigated the longitudinal effects of NR3C1 1 F exon methylation on the risk of depression following ACS and treatment outcomes.

METHODS

In total, 969 patients admitted for recent ACS were recruited within 2 weeks of ACS; 711 of these patients were followed up at 1 year. Depressive disorder was diagnosed according to DSM-IV criteria and included prevalent depressive disorder at baseline and incident or persistent depressive disorder at follow-up based on depression status at the two examinations. Of the 378 baseline participants who were diagnosed with depression, 255 participated in a randomized double-blind placebo-controlled trial of escitalopram, while the remaining 123 were managed with the usual medical treatment for ACS.NR3C1 1 F exon methylation was measured using peripheral blood samples, and various demographic and clinical characteristics were assessed as covariates.

RESULTS

Higher NR3C1 1 F exon methylation levels were independently associated with prevalent depressive disorder at baseline but not with incident or persistent depressive disorder at follow-up based on logistic regression analyses adjusted for covariates. The effects of escitalopram on the remission of depressive symptoms was not influenced by NR3C1 1 F exon methylation status in ACS patients, but a placebo effect on the remission of depressive symptoms was observed, particularly in patients with lower methylation levels.

CONCLUSIONS

ACS patients with higher NR3C1 1 F exon methylation levels were at higher risk of developing depressive disorder within 2 weeks of ACS. Additionally, adequate antidepressant treatment may be effective for the remission of depressive symptoms regardless of NR3C1 1 F exon methylation status.

Epigenetic and Neurological Impairments Associated with Early Life Exposure to Persistent Organic Pollutants

The incidence of neurodevelopmental and neurodegenerative diseases worldwide has dramatically increased over the last decades. Although the aetiology remains uncertain, evidence is now growing that exposure to persistent organic pollutants during sensitive neurodevelopmental periods such as early life may be a strong risk factor, predisposing the individual to disease development later in life. Epidemiological studies have associated environmentally persistent organic pollutant exposure to brain disorders including neuropathies, cognitive, motor, and sensory impairments; neurodevelopmental disorders such as autism spectrum disorder (ASD) and attention-deficit hyperactivity disorder (ADHD); and neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis (ALS). In many ways, this expands the classical “Developmental Origins of Health and Disease” paradigm to include exposure to pollutants. This model has been refined over the years to give the current “three-hit” model that considers the individual's genetic factors as a first “hit.” It has an immediate interaction with the early-life exposome (including persistent organic pollutants) that can be considered to be a second “hit.” Together, these first two “hits” produce a quiescent or latent phenotype, most probably encoded in the epigenome, which has become susceptible to a third environmental “hit” in later life. It is only after the third “hit” that the increased risk of disease symptoms is crystallised. However, if the individual is exposed to a different environment in later life, they would be expected to remain healthy. In this review, we examine the effect of exposure to persistent organic pollutants and particulate matters in early life and the relationship to subsequent neurodevelopmental and neurodegenerative disorders. The roles of those environmental factors which may affect epigenetic DNA methylation and therefore influence normal neurodevelopment are then evaluated.

Promoter haplotypes of the corticotropin-releasing hormone encoding gene modulate the physiological stress response in vitro and in vivo

The corticotropin-releasing hormone (CRH) is a neuropeptide mediating stress responses. CRH exerts effects via the hypothalamus pituitary adrenal axis as well as immediate effects on the sympathetic-adrenal-medullary system. Genetic variants of the CRH promoter were previously found to be associated with altered CRH promoter activity and physiological reactions. Functional characterization of three CRH promoter haplotypes have been performed in vitro using a reporter gene assay under different stimulation conditions. Furthermore, 232 healthy subjects were genotyped and the influence of CRH haplotypes on basal parameters such as post-awakening cortisol and blood pressure as well as on stress reactivity measured after socially evaluated cold pressor test (SeCPT) was investigated. In vitro, CRH haplotype 2 showed the highest promoter activity under baseline conditions and after forskolin stimulation compared with other haplotypes. Forskolin treatment resulted in a two fold increase of haplotype 2 promoter activity compared with the baseline condition. Cell line-dependent promoter activation was found after hydrocortisone treatment. In vivo, CRH haplotype 2 carriers showed significant higher baseline blood pressure (p = .002) and blood pressure after SeCPT (p < .001), but did not differ in cortisol levels. This study provides converging evidence for the importance of CRH promoter variants on physiological stress response parameters.

Recollections of positive early caregiving relate to sympathetic nervous system activation and chronic inflammation in subsequent generations

To understand links between early experience and biomarkers of peripheral physiology in adulthood, this study examined associations between quality of early caregiving and markers of sympathetic activation and chronic inflammation in a sample of 52 low-income mothers and their preschool-aged children. Mothers reported on levels of positive caregiving experienced during childhood using the Structural Analysis of Social Behavior-Intrex. Mother and child sympathetic activation was indexed via pre-ejection period (PEP) at rest, during a dyadic social engagement task, and for children, while interacting with an unfamiliar adult. C-reactive protein (CRP) was collected using whole blood spots to assess levels of low-grade chronic inflammation. Results showed that mothers who reported experiencing more warm guidance and support for autonomy in early childhood displayed lower resting sympathetic nervous system activation (i.e., longer PEP) and lower chronic inflammation (i.e., CRP levels). Further, lower maternal chronic inflammation levels were associated with lower sympathetic activation (i.e., longer PEP) in their children at rest, and during social interactions with mother and a female stranger.

Quantitative DNA Methylation Analysis of DLGAP2 Gene using Pyrosequencing in Schizophrenia with Tardive Dyskinesia: A Linear Mixed Model Approach

Tardive dyskinesia (TD) is a side effect of antipsychotic medications used to treat schizophrenia (SCZ) and other mental health disorders. No study has previously used pyrosequencing to quantify DNA methylation levels of the DLGAP2 gene; while the quantitative methylation levels among CpG sites within a gene may be correlated. To deal with the correlated measures among three CpG sites within the DLGAP2 gene, this study analyzed DNA methylation levels of the DLGAP2 gene using a linear mixed model (LMM) in a Chinese sample consisting of 35 SCZ patients with TD, 35 SCZ without TD (NTD) and 34 healthy controls (HCs) collected in Beijing, China. The initial analysis using the non-parametric Kruskal-Wallis test revealed that three groups (TD, NTD and HC) had significant differences in DNA methylation level for CpG site 2 (p = 0.0119). Furthermore, the average methylation levels among the three CpG sites showed strong correlations (all p values < 0.0001). In addition, using the LMM, three groups had significant differences in methylation level (p = 0.0027); while TD, NTD and TD + NTD groups showed higher average methylation levels than the HC group (p = 0.0024, 0.0151, and 0.0007, respectively). In conclusion, the LMM can accommodate a covariance structure. The findings of this study provide first evidence of DNA methylation levels in DLGAP2 associated with SCZ with TD in Chinese population. However, TD just showed borderline significant differences to NTD in this study.

DNA methylation of the glucocorticoid receptor gene promoter in the placenta is associated with blood pressure regulation in human pregnancy

BACKGROUND

Blood pressure (BP) regulation during pregnancy is influenced by hormones of placental origin. It was shown that the glucocorticoid system is altered in hypertensive pregnancy disorders such as preeclampsia. Epigenetic mechanism might influence the activity of genes involved in placental hormone/hormone receptor synthesis/action during pregnancy.

METHOD

In the current study, we analyzed the association of 5'-C-phosphate-G-3' (CpG) site methylation of different glucocorticoid receptor gene (NR3C1) promoter regions with BP during pregnancy. The study was performed as a nested case-control study (n = 80) out of 1045 mother/child pairs from the Berlin Birth Cohort. Placental DNA was extracted and bisulfite converted. Nested PCR products from six NR3C1 proximal promoter regions [glucocorticoid receptor gene promotor region B (GR-1B), C (GR-1C), D (GR-1D), E (GR-1E), F (GR-1F), and H (GR-1H)] were analyzed by next generation sequencing.

RESULTS

NR3C1 promoter regions GR-1D and GR-1E had a much higher degree of DNA methylation as compared to GR-1B, GR-1F or GR-1H when analyzing the entire study population. Comparison of placental NR3C1 CpG site methylation among hypotensive, normotensive and hypertensive mothers revealed several differently methylated CpG sites in the GR-1F promoter region only. Both hypertension and hypotension were associated with increased DNA methylation of GR-1F CpG sites. These associations were independent of confounding factors, such as family history of hypertension, smoking status before pregnancy and prepregnancy BMI. Assessment of placental glucocorticoid receptor expression by western blot showed that observed DNA methylation differences were not associated with altered levels of placental glucocorticoid receptor expression. However, correlation matrices of all NR3C1 proximal promoter regions demonstrated different correlation patterns of intraregional and interregional DNA methylation in the three BP groups, putatively indicating altered transcriptional control of glucocorticoid receptor isoforms.

CONCLUSION

Our study provides evidence of an independent association between placental NR3C1 proximal promoter methylation and maternal BP. Furthermore, we observed different patterns of NR3C1 promoter methylation in normotensive, hypertensive and hypotensive pregnancy.

The role of genetic variation in the glucocorticoid receptor (NR3C1) and mineralocorticoid receptor (NR3C2) in the association between cortisol response and cognition under acute stress

Although HPA - axis reactivity has repeatedly been related to cognitive functioning, ambiguity remains regarding the direction of the effect, i.e. whether it benefits or impairs functioning. Genetic factors that contribute to HPA - axis reactivity on the one hand and to cognitive functioning on the other could therefore help clarify the association between stress and cognition. We genotyped 10 single nucleotide polymorphisms (SNPs) on the NR3C1 gene (rs10482682, rs33389, rs10482633, rs10515522, rs2963156, rs4128428, rs9324918, rs41423247, rs6189, rs10052957) coding for the glucocorticoid receptor (GR) and 4 SNPs on the NR3C2 gene (rs6810951, rs4635799, rs11099695, rs2070950) coding for the mineralocorticoid receptor (MR) and required N=126 healthy males to perform tasks assessing attention and reasoning before and after experiencing an acute laboratory stressor (the Socially Evaluated Cold Pressor Test, SECPT). Haplotype analyses revealed significant effects of NR3C1 (p=0.011) and NR3C2 (p=0.034) on cortisol stress response. NR3C2 also influenced attentional performance via an interaction with stress-induced cortisol response (p<0.001). Neither NR3C1 haplotype nor NR3C2 haplotype was associated with reasoning abilities. Results suggest that the association between stress induced cortisol reactivity and cognition strongly depends on genetic variation. The idea of an optimal arousal level depending on stress reactivity and genetic disposition is discussed.

The role of DNA methylation in the association between childhood adversity and cardiometabolic disease

Growing evidence suggests that adverse environmental stimuli, especially during sensitive periods in early life, may lead to cardiometabolic disease in later life. However, the underlying biological mechanisms remain a mystery. Recent studies inferred that epigenetic modifications are likely involved. We review recent studies, primarily focused on the findings from human studies, to indicate the role of DNA methylation in the associations between childhood adversity and cardiometabolic disease in adulthood. In particular, we focused on DNA methylation modifications in genes regulating the hypothalamus-pituitary-adrenal axis as well as the immune system.

Critical Illness-Related Corticosteroid Insufficiency (CIRCI): A Narrative Review from a Multispecialty Task Force of the Society of Critical Care Medicine (SCCM) and the European Society of Intensive Care Medicine (ESICM)

OBJECTIVE

To provide a narrative review of the latest concepts and understanding of the pathophysiology of critical illness-related corticosteroid insufficiency (CIRCI).

PARTICIPANTS

A multi-specialty task force of international experts in critical care medicine and endocrinology and members of the Society of Critical Care Medicine and the European Society of Intensive Care Medicine.

DATA SOURCES

Medline, Database of Abstracts of Reviews of Effects (DARE), Cochrane Central Register of Controlled Trials (CENTRAL) and the Cochrane Database of Systematic Reviews.

RESULTS

Three major pathophysiologic events were considered to constitute CIRCI: dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, altered cortisol metabolism, and tissue resistance to glucocorticoids. The dysregulation of the HPA axis is complex, involving multidirectional crosstalk between the CRH/ACTH pathways, autonomic nervous system, vasopressinergic system, and immune system. Recent studies have demonstrated that plasma clearance of cortisol is markedly reduced during critical illness, explained by suppressed expression and activity of the primary cortisol-metabolizing enzymes in the liver and kidney. Despite the elevated cortisol levels during critical illness, tissue resistance to glucocorticoids is believed to occur due to insufficient glucocorticoid alpha-mediated anti-inflammatory activity.

CONCLUSIONS

Novel insights into the pathophysiology of CIRCI add to the limitations of the current diagnostic tools to identify at-risk patients and may also impact how corticosteroids are used in patients with CIRCI.

Correlation between polymorphisms of the NR3C1 gene and glucocorticoid effectiveness in patients with pemphigus vulgaris

Glucocorticoid (GC) resistance is the major obscule in the treatment of pemphigus vulgaris (PV) for both patients and clinicans with unclear mechanism. A hypotheis for this resistance is the mutations or polymorphisms present in the nuclear receptor subfamily 3, group C, member 1 (NR3C1) gene that encodes receptors for steroid hormones. This study aimed to investigate the association between NR3C1 gene polymorphisms and GC effectiveness in PV patients. 94 PV patients (64 GC-sensitive and 30 GC-resistant) and 100 healthy volunteers were enrolled in this case-control study. The genotyping of single nucleotide polymorphisms (SNPs) in BCL1, Arg23Lys, Asn363Ser 1548 t-insert, and le747Met, together with tag-SNP sites of the NR3C1 gene were evaluated. No significant differences were observed in genotypic and allelic frequencies of the 16 SNPs between PV patients and healthy volunteers. However, SNPs rs 11745958 C/T (OR: 8.95) and rs17209237 A/G (OR: 4.07) may be associated with an increased risk of GC resistance, while rs 33388 A/T (OR: 0.45) and rs7701443 A/G (OR: 0.51) may indicate a decreased risk of GC resistance in PV patients. NR3C1 gene variation may be associated with GC resistance in PV patients. More extensive genetic analyses and mechanistic analysis are required for further exploration.

Biological determinants of health: Genes, microbes, and metabolism exemplars of nursing science

BACKGROUND

Increasingly, nurse scientists are incorporating "omics" measures (e.g., genomics, transcriptomics, proteomics, and metabolomics) in studies of biologic determinants of health and behavior. The role of omics in nursing science can be conceptualized in several ways: (a) as a portfolio of biological measures (biomarkers) to monitor individual risk, (b) as a set of combined data elements that can generate new knowledge based on large and complex patient data sets, (c) as baseline information that promotes health education and potentially personalized interventions, and (d) as a platform to understand how environmental parameters (e.g., diet) interact with the individual's physiology.

PURPOSE

In this article, we provide exemplars of nursing scientists who use omics to better understand specific health conditions.

METHODS

We highlight various ongoing nursing research investigations incorporating omics technologies to study chronic pain vulnerability, risk for a pain-related condition, cardiometabolic complications associated with pregnancy, and as biomarkers of response to a dietary intervention.

DISCUSSION

Omics technologies add an important dimension to nursing science across many foci of investigation. However, there are also challenges and opportunities for nurse scientists who consider using omics in their research.

CONCLUSION

The integration of omics holds promise for increasing the impact of nursing research and practice on population health outcomes.

Allostatic load and comorbidities: A mitochondrial, epigenetic, and evolutionary perspective

Stress-related pathophysiology drives comorbid trajectories that elude precise prediction. Allostatic load algorithms that quantify biological "wear and tear" represent a comprehensive approach to detect multisystemic disease processes of the mind and body. However, the multiple morbidities directly or indirectly related to stress physiology remain enigmatic. Our aim in this article is to propose that biological comorbidities represent discrete pathophysiological processes captured by measuring allostatic load. This has applications in research and clinical settings to predict physical and psychiatric comorbidities alike. The reader will be introduced to the concepts of allostasis, allostasic states, allostatic load, and allostatic overload as they relate to stress-related diseases and the proposed prediction of biological comorbidities that extend rather to understanding psychopathologies. In our transdisciplinary discussion, we will integrate perspectives related to (a) mitochondrial biology as a key player in the allostatic load time course toward diseases that "get under the skin and skull"; (b) epigenetics related to child maltreatment and biological embedding that shapes stress perception throughout lifespan development; and

Longitudinal changes in glucocorticoid receptor exon 1F methylation and psychopathology after military deployment

Several cross-sectional studies have demonstrated the relevance of DNA methylation of the glucocorticoid receptor exon 1_F region (GR-1_F) for trauma-related psychopathology. We conducted a longitudinal study to examine GR-1_F methylation changes over time in relation to trauma exposure and the development of post-deployment psychopathology. GR-1_F methylation (52 loci) was quantified using pyrosequencing in whole blood of 92 military men 1 month before and 6 months after a 4-month deployment period to Afghanistan. GR-1_F methylation overall (mean methylation and the number of methylated loci) and functional methylation (methylation at loci associated with GR exon 1_F expression) measures were examined. We first investigated the effect of exposure to potentially traumatic events during deployment on these measures. Subsequently, changes in GR-1_F methylation were related to changes in mental health problems (total Symptom Checklist-90 score) and posttraumatic stress disorder (PTSD) symptoms (Self-Report Inventory for PTSD). Trauma exposure during deployment was associated with an increase in all methylation measures, but development of mental health problems 6 months after deployment was only significantly associated with an increased functional methylation. Emergence of post-deployment PTSD symptoms was not related to increased functional methylation over time. Pre-deployment methylation levels did not predict post-deployment psychopathology. To our knowledge, this is the first study to prospectively demonstrate trauma-related increases in GR-1_F methylation, and it shows that only increases at specific functionally relevant sites predispose for post-deployment psychopathology.

HPA axis dysregulation, NR3C1 polymorphisms and glucocorticoid receptor isoforms imbalance in metabolic syndrome

CONTEXT

Metabolic syndrome (MetS) shares several similarities with hypercortisolism.

OBJECTIVES

To evaluate hypothalamic-pituitary-adrenal (HPA) axis sensitivity to dexamethasone (DEX), NR3C1 single nucleotide polymorphisms (SNPs), and expression of glucocorticoid receptor (GR) isoforms and cytokines in peripheral immune cells of MetS patients and controls.

DESIGN

Prospective study with 40 MetS patients and 40 controls was conducted at the Ribeirão Preto Medical School University Hospital.

METHODS

Plasma and salivary cortisol were measured in basal conditions and after 0.25, 0.5, and 1 mg of DEX given at 2300 h. In addition, p.N363S (rs6195), p.ER22/23EK (rs6189-6190), and BclI (rs41423247) SNPs were evaluated by quantitative polymerase chain reaction allelic discrimination. Exons 3 to 9 and exon/intron boundaries of NR3C1 were sequenced. GR isoforms and cytokines (IL1B, IL2, IL4, IL6, IL8, IL10, IFNγ, TNFα) expression were assessed by quantitative polymerase chain reaction.

RESULTS

Plasma and salivary cortisol (nmol/L) after 1-mg DEX were higher in MetS patients compared with controls (PF: 70.2 ± 17.3 vs 37.9 ± 2.6, P = .02, and SF: 4.9 ± 1.7 vs 2.2 ± 0.3, P < .0001). After all DEX doses, a lower number of MetS patients suppressed plasma and salivary cortisol compared with controls. The BclI genotypic frequencies (%) differed between patients (CC:56/CG:44) and controls (CC:50/CG:32.5/GG:17.5) (P = .03). The GRβ was overexpressed (fold = 100.0; P = .002) and IL4 (fold = -265.0; P < .0001) was underexpressed in MetS.

CONCLUSION

MetS patients exhibited decreased HPA sensitivity to glucocorticoid feedback. Moreover, the BclI polymorphism lower frequency, GRβ overexpression, and IL4 underexpression might underlie the molecular mechanism of glucocorticoid resistance in MetS. Thus, HPA axis dysregulation might contribute to MetS pathogenesis.

Translational relevance of rodent models of hypothalamic-pituitary-adrenal function and stressors in adolescence

Elevations in glucocorticoids that result from environmental stressors can have programming effects on brain structure and function when the exposure occurs during sensitive periods that involve heightened neural development. In recent years, adolescence has gained increasing attention as another sensitive period of development, a period in which pubertal transitions may increase the vulnerability to stressors. There are similarities in physical and behavioural development between humans and rats, and rats have been used effectively as an animal model of adolescence and the unique plasticity of this period of ontogeny. This review focuses on benefits and challenges of rats as a model for translational research on hypothalamic-pituitary-adrenal (HPA) function and stressors in adolescence, highlighting important parallels and contrasts between adolescent rats and humans, and we review the main stress procedures that are used in investigating HPA stress responses and their consequences in adolescence in rats. We conclude that a greater focus on timing of puberty as a factor in research in adolescent rats may increase the translational relevance of the findings.

DNA methylation: conducting the orchestra from exposure to phenotype?

DNA methylation, through 5-methyl- and 5-hydroxymethylcytosine (5mC and 5hmC), is considered to be one of the principal interfaces between the genome and our environment, and it helps explain phenotypic variations in human populations. Initial reports of large differences in methylation level in genomic regulatory regions, coupled with clear gene expression data in both imprinted genes and malignant diseases, provided easily dissected molecular mechanisms for switching genes on or off. However, a more subtle process is becoming evident, where small (<10 %) changes to intermediate methylation levels are associated with complex disease phenotypes. This has resulted in two clear methylation paradigms. The latter “subtle change” paradigm is rapidly becoming the epigenetic hallmark of complex disease phenotypes, although we are currently hampered by a lack of data addressing the true biological significance and meaning of these small differences.

Our initial expectation of rapidly identifying mechanisms linking environmental exposure to a disease phenotype led to numerous observational/association studies being performed. Although this expectation remains unmet, there is now a growing body of literature on specific genes, suggesting wide ranging transcriptional and translational consequences of such subtle methylation changes. Data from the glucocorticoid receptor (NR3C1) has shown that a complex interplay between DNA methylation, extensive 5′UTR splicing, and microvariability gives rise to the overall level and relative distribution of total and N-terminal protein isoforms generated. Additionally, the presence of multiple AUG translation initiation codons throughout the complete, processed mRNA enables translation variability, hereby enhancing the translational isoforms and the resulting protein isoform diversity, providing a clear link between small changes in DNA methylation and significant changes in protein isoforms and cellular locations. Methylation changes in the NR3C1 CpG island alters the NR3C1 transcription and eventually protein isoforms in the tissues, resulting in subtle but visible physiological variability.

This review addresses the current pathophysiological and clinical associations of such characteristically small DNA methylation changes, the ever-growing roles of DNA methylation and the evidence available, particularly from the glucocorticoid receptor of the cascade of events initiated by such subtle methylation changes, as well as addressing the underlying question as to what represents a genuine biologically significant difference in methylation.

Dehydroepiandrosterone-sulfate is associated with cardiovascular reactivity to stress in women

Cardiovascular stress reactivity is a predictor of atherosclerosis and cardiac events. Dehydroepiandrosterone (DHEA) protects against cardiovascular diseases, but results among previous studies have been inconsistent. We investigated the association between dehydroepiandrosterone-sulfate (DHEA-s) and cardiovascular stress reactivity in Japanese women and men. Among 979 healthy Japanese subjects (641 women and 338 men), serum levels of DHEA-s, systolic blood pressure (SBP) and diastolic blood pressure (DBP), heart rate, heart rate variability, and peripheral blood flow were measured under rest and two types of task. Mean differences in measured variables during tasks and a post-task period were calculated as changes in stress reactivity. Variables of stress reactivity were adjusted for multiple potential confounding factors. In women, DHEA-s levels showed positive associations with changes in SBP and DBP (standardized beta=0.12, p=0.020; 0.17, 0.002, respectively). Stratification by menopausal status and other lifestyle factors (e.g., smoking status, alcohol consumption) were conducted. Significant positive associations remained in pre-menopausal (standardized beta=0.13, p=0.037; 0.18, 0.005), non-smoking (0.12, 0.010; 0.18, <0.001), and non-drinking women (0.14, 0.021; 0.21, 0.001), and women without a medical history (0.15, 0.020; 0.20, 0.001). In men, there was no significant association between DHEA-s levels and changes in stress reactivity. DHEA-s levels were positively associated with high blood-pressure reactivity to stress in women, and being menopausal, smoking, and alcohol consumption modified this association.