Background Shift work is a feature of many occupations and has been associated with a range of adverse health outcomes, including obesity, diabetes, depression and cancer. The main proposed mechanism linking them is a disruption in circadian rhythms, particularly among night shift workers. DNA methylation may serve as a biomarker for circadian disruption and a potential mechanism by which shift work influences disease risk. In the context of a longitudinal study, we aimed to investigate whether shift work is associated with DNA methylation. Methods Methylation profiling was performed using Illumina EPIC micro-arrays on whole-blood DNA samples, obtained from British Household Panel Survey (BHPS) participants of Understanding Society from 2010–2012. BHPS comprises a clustered random sample of households recruited in 1991, with all members followed annually. After pre-processing, 1175 samples and 857,071 CpG sites remained for investigation. Shift work variables were derived from 17 time points between 1991 and 2009: ever (n=359), current (n=88) and long-term (3 3 years) shift work (n=154) (night and rotating). Epigenome-wide association analysis was performed using multivariable regression with adjustment for age, sex, batch and blood processing day. Further models were adjusted for cell-type composition and socio-economic variables. Methylation age was also estimated based on the Horvath epigenetic clock and the impact of shift work on 'epigenetic age acceleration' (EAA) was investigated. Results In epigenome-wide association analysis, 50 CpG sites were associated with shift work with a nominal p-value<1 × 10-5 across the 9 main analyses, with the strongest signal of association at cg12880856 (PPARG) identified in relation to ever working night shifts (p=7.3 × 10−8). There was nominal evidence for an inverse association between current shift and rotating work with accelerated ageing (EAA) (mean difference=-0.98 (-1.93, -0.39); p=0.041 and −1.11 (−2.19,–0.04); p=0.041, respectively). Conclusion Shift work was associated with differential methylation in blood, including a CpG site in PPARG. This CpG site is specific to the Illumina EPIC array, not being present on the predecessor 450 K array, and represents a potentially novel finding. PPAR-gamma has been implicated in the pathology of obesity, diabetes and cancer, although further work is required to appraise the causal effect of methylation on health outcomes. Furthermore, there was some evidence that current shift workers had decelerated methylation age compared with non-shift workers. However, the number of shift workers in this study was relatively small and further validation of findings is required.

Multiple epidemiological studies suggest a relationship between advanced paternal age (APA) at conception and adverse neurodevelopmental outcomes in offspring, particularly with regard to increased risk for autism and schizophrenia. Conclusive evidence about how age-related changes in paternal gametes, or age-independent behavioral traits affect neural development is still lacking. Recent evidence suggests that the origins of APA effects are likely to be multidimensional, involving both inherited predisposition and de novo events. Here we provide a review of the epidemiological and molecular findings to date. Focusing on the latter, we present the evidence for genetic and epigenetic mechanisms underpinning the association between late fatherhood and disorder in offspring. We also discuss the limitations of the APA literature. We propose that different hypotheses relating to the origins of the APA effects are not mutually exclusive. Instead, multiple mechanisms likely contribute, reflecting the etiological complexity of neurodevelopmental disorders.

In order to determine the impact of the epigenetic response to traumatic stress on post-traumatic stress disorder (PTSD), this study examined longitudinal changes of genome-wide blood DNA methylation profiles in relation to the development of PTSD symptoms in two prospective military cohorts (one discovery and one replication data set). In the first cohort consisting of male Dutch military servicemen (n=93), the emergence of PTSD symptoms over a deployment period to a combat zone was significantly associated with alterations in DNA methylation levels at 17 genomic positions and 12 genomic regions. Evidence for mediation of the relation between combat trauma and PTSD symptoms by longitudinal changes in DNA methylation was observed at several positions and regions. Bioinformatic analyses of the reported associations identified significant enrichment in several pathways relevant for symptoms of PTSD. Targeted analyses of the significant findings from the discovery sample in an independent prospective cohort of male US marines (n=98) replicated the observed relation between decreases in DNA methylation levels and PTSD symptoms at genomic regions in ZFP57, RNF39 and HIST1H2APS2. Together, our study pinpoints three novel genomic regions where longitudinal decreases in DNA methylation across the period of exposure to combat trauma marks susceptibility for PTSD.

Despite moderate heritability estimates, progress in uncovering the molecular substrate underpinning major depressive disorder (MDD) has been slow. In this study, we used prefrontal cortex (PFC) gene expression from a genetic rat model of MDD to inform probe set prioritization in PFC in a human post-mortem study to uncover genes and gene pathways associated with MDD. Gene expression differences between Flinders sensitive (FSL) and Flinders resistant (FRL) rat lines were statistically evaluated using the RankProd, non-parametric algorithm. Top ranking probe sets in the rat study were subsequently used to prioritize orthologous selection in a human PFC in a case–control post-mortem study on MDD from the Stanley Brain Consortium. Candidate genes in the human post-mortem study were then tested against a matched control sample using the RankProd method. A total of 1767 probe sets were differentially expressed in the PFC between FSL and FRL rat lines at (q⩽0.001). A total of 898 orthologous probe sets was found on Affymetrix’s HG-U95A chip used in the human study. Correcting for the number of multiple, non-independent tests, 20 probe sets were found to be significantly dysregulated between human cases and controls at q⩽0.05. These probe sets tagged the expression profile of 18 human genes (11 upregulated and seven downregulated). Using an integrative rat–human study, a number of convergent genes that may have a role in pathogenesis of MDD were uncovered. Eighty percent of these genes were functionally associated with a key stress response signalling cascade, involving NF- κ B (nuclear factor kappa-light-chain-enhancer of activated B cells), AP-1 (activator protein 1) and ERK/MAPK, which has been systematically associated with MDD, neuroplasticity and neurogenesis.

Our study is the first investigation of the effects of advanced paternal age (APA) on the developmental trajectory of social behavior in rodent offspring. Given the strong epidemiological association between APA and sexually dimorphic neurodevelopmental disorders that are characterized by abnormalities in social behavior (autism, schizophrenia), we assessed sociability in male and female inbred mice (C57BL/6J) across postnatal development (N=104) in relation to paternal age. We found differences in early social behavior in both male and female offspring of older breeders, with differences in this social domain persisting into adulthood in males only. We showed that these social deficits were not present in the fathers of these offspring, confirming a de novo origin of an altered social trajectory in the offspring generation. Our results, highly novel in rodent research, support the epidemiological observations in humans and provide evidence for a causal link between APA, age-related changes in the paternal sperm DNA and neurodevelopmental disorders in their offspring.

Here, we leverage a unique collection of 708 prospectively collected autopsied brains to assess the methylation state of the brain's DNA in relation to Alzheimer's disease (AD). We find that the level of methylation at 71 of the 415,848 interrogated CpGs is significantly associated with the burden of AD pathology, including CpGs in the ABCA7 and BIN1 regions, which harbor known AD susceptibility variants. We validate 11 of the differentially methylated regions in an independent set of 117 subjects. Further, we functionally validate these CpG associations and identify the nearby genes whose RNA expression is altered in AD: ANK1, CDH23, DIP2A, RHBDF2, RPL13, RNF34, SERPINF1 and SERPINF2. Our analyses suggest that these DNA methylation changes may have a role in the onset of AD since (1) they are seen in presymptomatic subjects and (2) six of the validated genes connect to a known AD susceptibility gene network.

International Journal of Developmental NeuroscienceVolume 47, Issue Part_A p. 50-51 Article ISDN2014_0171: Dynamic and sex-specific changes in DNA methylation during human fetal brain development H. Spiers, Corresponding Author H. Spiers n/a@.dne King's College London, UKSearch for more papers by this authorN.J. Bray, N.J. Bray King's College London, UKSearch for more papers by this authorE. Hannon, E. Hannon Exeter University, UKSearch for more papers by this authorL.C. Schalkwyk, L.C. Schalkwyk King's College London, UKSearch for more papers by this authorC.C. Wong, C.C. Wong King's College London, UKSearch for more papers by this authorR. Pidsley, R. Pidsley King's College London, UKSearch for more papers by this authorR.G. Smith, R.G. Smith King's College London, UKSearch for more papers by this authorJ. Mill, J. Mill King's College London, UK Exeter University, UKSearch for more papers by this author H. Spiers, Corresponding Author H. Spiers n/a@.dne King's College London, UKSearch for more papers by this authorN.J. Bray, N.J. Bray King's College London, UKSearch for more papers by this authorE. Hannon, E. Hannon Exeter University, UKSearch for more papers by this authorL.C. Schalkwyk, L.C. Schalkwyk King's College London, UKSearch for more papers by this authorC.C. Wong, C.C. Wong King's College London, UKSearch for more papers by this authorR. Pidsley, R. Pidsley King's College London, UKSearch for more papers by this authorR.G. Smith, R.G. Smith King's College London, UKSearch for more papers by this authorJ. Mill, J. Mill King's College London, UK Exeter University, UKSearch for more papers by this author First published: 05 November 2015 https://doi.org/10.1016/j.ijdevneu.2015.04.142Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume47, IssuePart_AISDN 2014 AbstractsDecember 2015Pages 50-51 RelatedInformation

Chronic pain is a global public health problem, but the underlying molecular mechanisms are not fully understood. Here we examine genome-wide DNA methylation, first in 50 identical twins discordant for heat pain sensitivity and then in 50 further unrelated individuals. Whole-blood DNA methylation was characterized at 5.2 million loci by MeDIP sequencing and assessed longitudinally to identify differentially methylated regions associated with high or low pain sensitivity (pain DMRs). Nine meta-analysis pain DMRs show robust evidence for association (false discovery rate 5%) with the strongest signal in the pain gene TRPA1 ( P =1.2 × 10 −13 ). Several pain DMRs show longitudinal stability consistent with susceptibility effects, have similar methylation levels in the brain and altered expression in the skin. Our approach identifies epigenetic changes in both novel and established candidate genes that provide molecular insights into pain and may generalize to other complex traits.

Autism spectrum disorder (ASD) defines a group of common, complex neurodevelopmental disorders. Although the aetiology of ASD has a strong genetic component, there is considerable monozygotic (MZ) twin discordance indicating a role for non-genetic factors. Because MZ twins share an identical DNA sequence, disease-discordant MZ twin pairs provide an ideal model for examining the contribution of environmentally driven epigenetic factors in disease. We performed a genome-wide analysis of DNA methylation in a sample of 50 MZ twin pairs (100 individuals) sampled from a representative population cohort that included twins discordant and concordant for ASD, ASD-associated traits and no autistic phenotype. Within-twin and between-group analyses identified numerous differentially methylated regions associated with ASD. In addition, we report significant correlations between DNA methylation and quantitatively measured autistic trait scores across our sample cohort. This study represents the first systematic epigenomic analyses of MZ twins discordant for ASD and implicates a role for altered DNA methylation in autism.

Transcriptional differences in interleukin-11 (IL11) after antidepressant treatment have been found to correspond to clinical response in major depressive disorder (MDD) patients. Expression differences were partly mediated by a single-nucleotide polymorphism (rs1126757), identified as a predictor of antidepressant response as part of a genome-wide association study. Here we attempt to identify whether DNA methylation, another baseline factor known to affect transcription factor binding, might also predict antidepressant response, using samples collected from the Genome-based Therapeutic Drugs for Depression project (GENDEP). DNA samples from 113 MDD individuals from the GENDEP project, who were treated with either escitalopram (n=80) or nortriptyline (n=33) for 12 weeks, were randomly selected. Percentage change in Montgomery–Åsberg Depression Rating Scale scores between baseline and week 12 were utilized as our measure of antidepressant response. The Sequenom EpiTYPER platform was used to assess DNA methylation across the only CpG island located in the IL11 gene. Regression analyses were then used to explore the relationship between CpG unit methylation and antidepressant response. We identified a CpG unit predictor of general antidepressant response, a drug by CpG unit interaction predictor of response, and a CpG unit by rs1126757 interaction predictor of antidepressant response. The current study is the first to investigate the potential utility of pharmaco-epigenetic biomarkers for the prediction of antidepressant response. Our results suggest that DNA methylation in IL11 might be useful in identifying those patients likely to respond to antidepressants, and if so, the best drug suited to each individual.

Stressful events early in life have been widely linked to behavioral phenotypes and have been implicated in the development of psychiatric disorders. Using a maternal separation paradigm, we investigated phenotypic and epigenetic changes following early life stress in two inbred strains of mice, C57BL/6J and DBA/2J. We found an increase in the corticosterone response to stress in male, C57BL/6J mice that had undergone maternal separation compared to controls. In addition, early life stress induced a number of mild but significant behavioral changes, many of which were sex and strain dependent. Following maternal separation anxiety was decreased in males but increased in DBA/2J females, DBA/2J males displayed reduced exploration of a novel object, and baseline activity was altered in males of both strains. Finally, we examined DNA methylation levels in the hippocampus across promoter regions of Nr3c1, Avp, and Nr4a1, and found altered levels at several CpG sites in maternally separated male mice compared to controls. This study contributes to a growing body of recent literature suggesting that epigenetic changes may mediate the impact of early life stress on behavior. In particular, we establish that the phenotypic and epigenetic responses to an adverse environment differ as a function of genetic background.

increased levels of IgG in the shocked animals (Student’s t-test: t = 2.453, df = 20, p = 0.023). This supported our previous findings and strengthens the hypothesis of IgG as a biomarker of stress. Next, we wanted to know if pharmacological treatment of traumatized mice also affects IgG levels. Preliminary data, obtained by treating traumatized and control mice with the mood stabilizer valproic acid, indicate that the stress associated increase in IgG is diminished in treated mice. In conclusion, in this study we detected increased IgG expression in stressed animals. This might indicate a possible unspecific immune activation, which is in agreement with findings of other studies analyzing inflammatory parameters in PTSD [3]. Interestingly, IgG levels were restored by pharmacological treatment. Altogether, these results lead us to propose IgG as a novel potential biomarker for traumatic stress: IgG levels are measurable in the blood and thus are easily applicable in the clinical practice.

Communication between various ovarian cell types is a prerequisite for folliculogenesis and ovulation. In antral follicles granulosa cells divide into two distinct populations of mural and cumulus granulosa cells (CGC), enveloping the antrum and surrounding the oocyte, respectively. Both cell types, with the mural compartment in excess, contribute to the floating granulosa cell (FGC) population in the follicular fluid. The aim of this study was to compare the transcriptomes of FGC and CGC in stimulated antral follicles obtained from 19 women undergoing IVF-ICSI procedure. FGC were obtained from follicular fluid during the follicle puncture procedure and CGC were acquired after oocyte denudation for micromanipulation. Gene expression analysis was conducted using the genome-wide Affymetrix transcriptome array. The expression profile of the two granulosa cell populations varied significantly. Out of 28 869 analysed transcripts 4480 were differentially expressed (q-value < 10(-4)) and 489 showed > or =2-fold difference in the expression level with 222 genes up-regulated in FGC and 267 in CGC. The transcriptome of FGC showed higher expression of genes involved in immune response, hematological system function and organismal injury, although CGC had genes involved in protein degradation and nervous system function up-regulated. Cell-to-cell signalling and interaction pathways were noted in both cell populations. Furthermore, numerous novel transcripts that have not been previously described in follicular physiology were identified. In conclusion, our results provide a solid basis for future studies in follicular biology that will help to identify molecular markers for oocyte and embryo viability in IVF.