Clinical Epigenetics

IntroductionThere is great current interest in the potential application of DNA methylation alterations in peripheral blood leukocytes (PBL) as biomarkers of susceptibility, progression and treatment response in inflammatory bowel disease (IBD). However, the intra-individual stability of PBL methylation in IBD has not been characterised. Here, we studied the long-term stability of all probes located on the Illumina HumanMethylation EPIC BeadChip array. MethodsWe followed a cohort of 46 adult IBD patients (36 Crohns disease (CD), 10 ulcerative colitis (UC), median age 44 (IQR: 27-56), 50% female) that received standard care without any intervention at the Amsterdam UMC. Paired PBL samples were collected at two time points with a median 7 (range: 2-9) years in between. Differential methylation and intra-class correlation (ICC) analyses were used to identify time-associated differences and temporally stable CpGs, respectively. ResultsAround 60% of all EPIC array loci presented poor intra-individual stability (ICC <0.50); 78.114 ({approx}9%) showed good (ICC 0.75 - 0.89); and 41.274 ({approx}5%) excellent (ICC [&ge;]0.90) stability. Focusing on previously identified consistently differentially methylated positions indicated that 22 CD-, 11 UC-, and 24 IBD-associated loci demonstrated high stability (ICC [&ge;]0.75) over time; of these, we observed a marked stability of CpG loci associated to the HLA genes. ConclusionOur data provide insight into the long-term stability of the PBL DNA methylome within an IBD context, facilitating the selection of biologically relevant and robust IBD-associated epigenetic biomarkers with increased potential for independent validation. These data also have potential implications in understanding disease pathogenesis.

BackgroundThe detection of alterations in DNA methylation (DNAm) in normal human tissues may provide molecular insights for cancer development, the estimation of personal cancer risk, and a basis for early diagnosis of malignancies to reduce cancer lethality. Thus, whether DNAm allows discrimination between healthy normal and normal tumor-adjacent renal tissues is an important question. MethodsDNAm of loci in the LINE1 repetitive sequence and ANKRD34B, NHLH2, TBR1, and ZIC1 was measured in a total of 493 tissue samples representing 342 normal autopsy and 151 histopathological normal tumor-adjacent renal tissues by pyro-sequencing a total of 22 CpG sites. ResultsUnsupervised k-means clustering demonstrated a significant imbalance of tissue samples in three stable tissue clusters. Random forest classification demonstrated discrimination of normal and normal tumor-adjacent renal tissues with a median area under the ROC curve of 0.81 (p=2.7x10-9, diagnostic odds ratio 10.4). Variable importance analysis revealed CpG sites in LINE1 and ANKRD34B as the most important model contributors. ConclusionsDNAm alterations in normal tissues allow detection of renal cancer with high diagnostic efficiency, defining a DNAm field effect in the kidney. The methylation signature may serve as a basis for an epigenetic DNAm clock permitting estimation of individual renal cancer risk.

BackgroundColorectal cancer (CRC) is associated with patient demographics, lifestyle exposures and molecular alterations. However, it is not possible to determine which adenomas will progress to CRC, as ethically it is unacceptable to leave and follow adenomas. We hypothesised that certain lifestyle exposures at high levels could precondition exposed bowel tissue by changing and aging it, increasing the risks of deleterious DNA methylation and genetic alterations. We used a novel study design comparing adenomas with concurrent CRC (thus more likely exposed to deleterious lifestyle effects) to single adenomas in bowels with no history of CRC; we called these high (HR) and low-risk (LR) adenomas respectively. MethodsWe carried out a discovery and replication epigenome-wide association study (EWAS) on 106 HR and 111 LR adenomas, profiled with MethylationEPIC BeadChips. In order, to identify differentially methylated positions (DMP), regions (DMR), and DNAm (DNAmethylation) lifestyle exposures and risks, with adjustment for confounders, and gene ontology (GO) and pathway enrichment. Then, two open-source gene expression omnibus (GEO) validation datasets (52, 57 and 49, 48 HR and LR normal bowel tissues respectively) were analysed for these DNAm lifestyle exposures and risks, with adjustment for confounders. ResultsOur EWAS found 5 Bonferroni significant DMPs with absolute delta betas [&ge;] 5%, and 14 significant DMRs with absolute mean DMR delta betas [&ge;] 5%, replicated in the GPX7, RGS3 and TMEM135 cancer-associated genes. DNAm high alcohol exposures were strongly associated with increased risk of HR adenomas (odds ratio (OR) per standard deviation (SD) = 2.16 (95% confidence interval (CI) 1.55 - 3.09, p-value = 9.7 x 10-6)). In the validation datasets, DNAm high alcohol (ORperSD = 2.12 (95% CI 1.35 - 3.55, p-value = 2.0 x 10-3) and ORperSD = 1.79 (95% CI 1.14 - 2.96, p-value = 1.7 x 10-2)), and high body mass index (BMI) exposures (ORperSD = 1.72 (95% CI 1.13 - 2.73, p-value = 1.5 x 10-2)) were associated with increased risk of HR normal bowel tissues. ConclusionsHigh alcohol and BMI exposures may precondition normal bowel tissues and adenomas for increased risk of DNA methylation alterations associated with CRC progression. The DNAm exposure signatures and our newly identified genes may be useful epigenetic biomarkers for CRC prevention.

BackgroundEpigenome-wide association studies (EWAS) have identified associations between DNA methylation and blood pressure, yet most rely on single-time-point data and cannot capture how methylation and blood pressure relationships change with age. MethodsWe conducted a longitudinal EWAS of 1,945 blood samples from 976 participants in the Multi-Ethnic Study of Atherosclerosis using a spline-based varying-coefficient model to detect age-dependent associations between DNA methylation in blood and blood pressure traits. Findings were evaluated for replication in 1,187 samples from the Framingham Heart Study. Models were adjusted for sex, ancestry, and leukocyte composition to account for cellular heterogeneity. ResultsSix CpG sites showed significant age-dependent associations with systolic or pulse pressure after correction for multiple testing. These included loci within STIP1, CSRP1, and KDM6A that replicated in the Framingham cohort. Several CpG sites demonstrated a reversal of effect direction with advancing age, where higher methylation was associated with higher systolic pressure in younger adults but lower pressure later in life. Pathway enrichment analyses identified focal adhesion, actin cytoskeleton remodeling, and Wnt/{beta}-catenin signaling, which are processes relevant to vascular aging. Drug target mapping identified 23 FDA-approved agents interacting with genes at these loci. ConclusionsBlood-derived DNA methylation shows dynamic age-related associations with blood pressure that likely reflect systemic or vascular aging processes rather than direct cellular mediation. Longitudinal analytical frameworks can reveal temporal patterns in epigenetic variation that are not detectable in single time point studies and may inform the discovery of biomarkers for age related cardiovascular risk.

BackgroundThe Developmental Origins of Adult Disease (DOAD) theory predicts that prenatal and early life events shape adult health outcomes. Birth weight is a useful indicator of the foetal experience, and has been associated with multiple adult health outcomes. DNA methylation (DNAm) is one plausible mechanism behind the relationship of birth weight to adult health. MethodsThe Generation Scotland study allows data linkage to historic Scottish birth cohorts, and birth records held through the NHS Information and Statistics Division. Data linkage with these sources yielded a sample of 4, 710 individuals. Health measures were related to birth weight in regression models. An epigenome-wide association study (EWAS) was performed in a subgroup (n=1, 395), relating adult DNAm from whole blood to birth weight, with replication in an independent sample (n=362). Associations between birth weight and epigenetic clocks were also assessed. FindingsHigher birth weight was significantly associated with reduced incidence of depression and osteoarthritis, higher body mass index, and higher general intelligence (absolute standardised effect size range 0{middle dot}04 to 0{middle dot}30, p(FDR)<0{middle dot}05). Meta-analysis of discovery and replication EWAS studies yielded one genome-wide significant CpG site (p=5{middle dot}97x10-9), cg00966482. Significant associations between birth weight and Grim Age (p=0{middle dot}0014) and DNAm-derived telomere length (p=3{middle dot}3x10-4) are also described. InterpretationOur results demonstrate associations between birth weight and adult health outcomes, with particularly striking effects for depression risk. It also provides support for an association between birth weight and DNAm, describing the first significant EWAS site associated with birth weight in an adult sample. FundingWellcome Trust Strategic Award 104036/Z/14/Z Research in ContextO_ST_ABSEvidence before this studyC_ST_ABSThe associations between birth weight and various adult health outcomes have been well established. DNA methylation is a plausible mechanism through which early life experiences may continue to affect health throughout the lifecourse; however, evidence for birth weight associations with DNA methylation in adulthood has not yet been robustly established. This is likely due to small sample sizes of previous samples, as well as the use of poor-quality birth weight data, such as binary low/normal variables or retrospective self-report. Alternatively, work has attempted to describe the persistence into adulthood of DNA methylation at sites identified at birth. Added value of this studyWe investigated genome-wide differential DNA methylation patterns from whole blood using data linkage-derived, continuous birth weight data, in the largest reported adult sample (n=1, 395) with replication (n=362) and meta-analysis. Meta-analysis revealed one epigenome-wide significant CpG site, to our knowledge the first significant EWAS result reported for birth weight in a an adult sample. In addition, we found associations between birth weight and GrimAge and a DNA methylation-derived measure of telomere length, demonstrating accelerated biological ageing in lower birth weight individuals. Together, these results suggest differential methylation exists in adulthood related to birth weight, and this may be relevant to health and mortality. Implications of all the available evidenceAlthough CpG sites differentially methylated with birth weight at parturition may not remain so throughout life, the adult epigenome may still provide information on the impact of birth weight on health outcomes. The adult epigenome, therefore, may represent a useful archive of the foetal experience which results in birth weight variability, and this information may provide clinically useful information in mid-life.

BackgroundThe mechanisms linking UV radiation and vitamin D exposure to the risk of acquiring the latitude and critical period dependent autoimmune disease, multiple sclerosis, is unclear. We examined the effect of vitamin D on DNA methylation as well as DNA methylation at vitamin D receptor binding sites in adult and paediatric myeloid cells. ResultsVery few DNA methylation changes occurred in adult and paediatric cells treated with calcitriol. However, several VDR binding sites across the genome demonstrated increased DNA methylation in cells of adult origin. Genes associated with these VDR binding sites were enriched for intracellular signalling and cell activation pathways, suggesting that age-dependent potential for myeloid cell differentiation and adaptive immune system regulation may be encoded for by DNA methylation. ConclusionsThese results suggest vitamin D exposure at critical periods in immune system development may contribute to the well characterised latitude related differences in autoimmune disease incidence.

BackgroundInflammatory bowel diseases (IBDs) are chronic inflammatory disorders with a dysregulated immune response partly influenced by environmental factors. DNA methylation (DNAm), a key epigenetic mechanism, is implicated in the etiology of complex diseases, including IBD. Epigenetic clocks, which use DNAm patterns to estimate biological aging, have been increasingly linked to various health and disease states. Previous studies have associated DNAm with IBD, and first- and second-generation epigenetic clocks with IBD subtypes. ResultsIn a discovery IBD cohort (n=149) with 8-year clinical follow-up data, we explored the relationship between DNAm variation, second- and third-generation epigenetic clocks, and IBD clinicopathological outcomes, including disease subtype, activity, and recurrence. One CpG site was significantly differentially methylated (Benjamini-Hochberg adjusted p-value<0.05) in patients with clinical recurrence of disease over the long term (i.e., after the first year of study) compared to non-recurrence (no treatment escalation after 8 years). Next, we assessed DNAm aging signatures and IBD outcomes using logistic regression. Individuals with IBD exhibited significantly increased epigenetic aging, as measured by GrimAge, GrimAge2, and DunedinPACE, compared with controls. These associations were replicated in two independent IBD cohorts (GSE87648 (n=377) and GSE112611 (n=238)). Additionally, in UC patients, the active disease group was associated with higher age acceleration (GrimAge (U=669, p=0.003)) and higher pace of aging (DunedinPACE (t=3.233, 0.002)) compared to the inactive group. In the discovery cohort, DunedinPACE outperforms CRP measures in discriminating activity in UC patients with an AUC, sensitivity and specificity of 0.71, 69.5% and 68.7% respectively, highlighting its potential as a useful biomarker of activity in UC. ConclusionsOverall, we present strong evidence that dynamic age-related DNAm changes can be used to differentiate between IBD (including separately by subtype) and controls. Furthermore, our study provides important new evidence that DunedinPACE may have utility as a biomarker for monitoring disease recurrence in IBD patients and may be a strong marker of disease activity in UC patients. Overall, this suggests that blood-based DNAm signatures could serve as biomarkers for detection and monitoring of IBD.

BackgroundAdverse childhood experiences (ACEs) are correlated with accelerated epigenetic aging, but it is not clear whether altered epigenetic aging from childhood adversities persists into adulthood and can be transmitted to the next generation. Thus, we tested whether mothers childhood adversity is associated with accelerated epigenetic aging during pregnancy and in their newborn offspring. MethodsData were from the Avon Longitudinal Study of Parents and Children (ALSPAC) sub-study, Accessible Resource for Integrated Epigenomic Studies (ARIES). Women provided retrospective self-reports during pregnancy of ACE exposure. DNA methylation was measured in mothers during pregnancy and cord blood at birth. Estimates of epigenetic age acceleration were calculated using Principal Components of Horvath, Hannum skin & blood, GrimAge, PhenoAge, and DunedinPACE epigenetic clocks for mothers; and the Knight and Bohlin cord blood clocks for newborns. Associations between a cumulative maternal ACE score and epigenetic age acceleration were estimated using linear regression models, adjusting for maternal age at pregnancy, smoking during pregnancy, education, and pre-pregnancy BMI. Models for offspring were stratified by sex and additionally adjusted for gestation age. ResultsMothers total ACE score was positively associated with accelerated maternal PhenoAge and GrimAge. In newborn offspring, mothers total ACE score was positively associated with accelerated epigenetic aging in males using the Bohlin clock, but not in females using either epigenetic clock. We found male offsprings epigenetic age was accelerated in those born to mothers exposed to neglect using the Knight clock; and parental substance abuse using the Bohlin clock. ConclusionOur results show that mothers ACE exposure is associated with DNAm age acceleration in male offspring, supporting the notion that DNAm age could be a marker of intergenerational biological embedding of mothers childhood adversity. This is consistent with findings on vulnerability of male fetuses to environmental insults.

IntroductionAberrant DNA methylation is frequently observed in colorectal cancer (CRC), but the underlying mechanisms are poorly understood. Ten-Eleven Translocation (TET) dioxygenases and DNA repair enzyme Thymine DNA Glycosylase (TDG) are involved in active DNA demethylation by generating and removing, respectively, novel oxidized cytosine species. Mutations of TET1 and TDG, and alterations of the levels of oxidized cytosine species have been identified in human CRC cases, but the biological significance of the TET-TDG demethylation axis in intestinal tumorigenesis is unclear.\n\nMaterial and MethodsWe generated ApcMin mice with additional inactivation of Tet1 and/or Tdg, and characterized the methylome and transcriptome of intestinal adenomas by DREAM and RNA sequencing, respectively.\n\nResultsTet1- and/or Tdg-deficient ApcMin mice show enhanced intestinal tumorigenesis in comparison to wild type Tet1 and Tdg ApcMin mice. Specifically, Tet1 and/or Tdg-deficient ApcMin adenomas manifested increased size or features of erosion and stroma activation. Methylome analysis revealed progressive loss of global DNA hypomethylation in colonic adenomas from Tet1- and Tdg-deficient ApcMin mice, and hypermethylation of CpG islands in Tet1-deficient ApcMin mice. In addition, RNA sequencing showed upregulation of genes in inflammatory and immune response pathways in Tet1-and Tdg-mutant colonic adenomas compared to control ApcMin adenomas.\n\nConclusionsTaken together, these findings demonstrate the important role of active DNA demethylation mediated by TET-TDG in reducing intestinal tumor formation, by modulating the epigenome and inflammatory/immune responses. This study highlights a novel mechanism of epigenetic deregulation during intestinal tumorigenesis with diagnostic, therapeutic and prognostic implications.

BackgroundEpigenetic changes in the form of DNA methylation (DNAm) may act as biological markers of risk factors or adverse health states. We investigated associations between night shift work and established DNAm predictors of lifestyle, and compared them with those observed between night shift work and self-reported or conventionally-measured phenotypes. MethodsIn two cohort studies, Generation Scotland (GS) (n=7,028) and Understanding Society (UKHLS) (n=1,175), we evaluated associations between night shift work and four lifestyle factors (body mass index, smoking, alcohol, education) using both conventionally-measured phenotypes and DNA methylation-based scores proxying the phenotypes. DNA methylation-based measures of biological ageing were also generated using six established "epigenetic clocks". Meta-analysis of GS and UKHLS results was conducted using inverse-variance weighted fixed effects. ResultsNight shift work was associated with higher BMI (0.79; 95%CI 0.02, 1.56; p=0.04) and lower education (-0.18; -0.30, -0.07; p=0.002). There was weak evidence of association between night shift work and DNAm scores for smoking (0.06, -0.03, 0.15; p=0.18) and education (-0.24; -0.49, 0.01; p=0.06) in fully adjusted models. Two of the epigenetic age measures demonstrated higher age acceleration among night shift workers (0.80; 0.42, 1.18; p<0.001 for GrimAge and 0.46; 0.00, 0.92; p=0.05 for PhenoAge). ConclusionsNight shift work is associated with phenotypic and DNAm-based measures of lower education. Night shift work was also related to DNAm predictors of smoking and ageing.

BackgroundCancer evolution depends on epigenetic and genetic diversity. Historically, in multiple myeloma (MM), subclonal diversity and tumor evolution have been investigated mostly from a genetic perspective. ResultsHere, we combined the notions of epipolymorphism and epiallele switching to analyze DNA methylation heterogeneity in MM patients. We show that MM is characterized by the continuous accumulation of stochastic methylation at the promoters of development-related genes. High entropy change is associated with poor outcomes and depends predominantly on partially methylated domains (PMDs). These PMDs, which represent the major source of inter- and intrapatient DNA methylation heterogeneity in MM, are linked to other key epigenetic aberrations, such as CpG island (CGI)/transcription start site (TSS) hypermethylation and H3K27me3 redistribution as well as 3D organization alterations. In addition, transcriptome analysis revealed that intratumor methylation heterogeneity was associated with low-level expression and high variability. ConclusionWe propose that disordered methylation in MM is responsible for high epigenetic and transcriptomic instability allowing tumor cells to adapt to environmental changes by tapping into a pool of evolutionary trajectories.

Epigenetic clocks are regression models that predict biological age based on the DNA methylation patterns. They are developed using DNA methylation array data; however, systematic differences in the predicted values between the Infinium Methylation Screening Array (MSA) and Infinium MethylationEPIC v2.0 BeadChip (EPICv2) platforms have not been evaluated. We quantified the systematic differences between the MSA and EPICv2 arrays for six major epigenetic clocks (Horvath, Hannum, PhenoAge, GrimAge, GrimAge v2, and DunedinPACE) using 166 identical human blood samples measured on both platforms. The mean differences (MSA - EPICv2) ranged from -7.99 years for PhenoAge to 21.8 years for the Hannum clock, despite strong correlations between platforms (r = 0.854 - 0.991). Based on these training data, we developed three linear regression models to correct the MSA-based epigenetic clocks: Model 1 (offset location correction), Model 2 (slope and location correction), and Model 3 (slope and location correction with covariates). Validation on 48 independent samples measured at a different institution showed that all models reduced cross-platform bias. Although Model 3 tended to achieve the lowest bias; 0.204 years for PhenoAge and 0.383 years for GrimAge v2, Model 1, which was the simplest, provided a sufficient correction: -0.541 years of bias for PhenoAge and 0.516 for GrimAge v2. These methods are expected to enable reliable comparisons of epigenetic age across platforms and facilitate large-scale epigenetic studies.

BackgroundThe mA modification is the most abundant RNA epigenetic mark in colorectal cancer (CRC). In this study, we focused on Hakai, a methyltransferase writer-associated protein whose molecular function within the complex and link to CRC immune regulation remain poorly characterized. MethodsWe performed RNA-seq to assess transcriptomic changes after Hakai silencing in CRC models and MeRIP-seq to profile methylation alterations. Validation was carried out by Western blot, flow cytometry, ELISA, and RT-qPCR. Protein interactions within the writer complex were analysed by co-immunoprecipitation, and changes in protein localization by cell fractionation assays. Peripheral blood from healthy donors and lamina propria mononuclear cells from CRC patients were incubated with supernatants from Hakai-silenced CRC cells to evaluate effects on immune responses. ResultsHakai silencing induced phenotypic changes in both monolayer and 3D CRC cultures, while its impact on the global transcriptome was limited. However, significant alterations in the methylation of immune response-related genes and reduced total mA levels were observed. Hakai interacted with the writer-associated protein VIRMA, and its silencing altered the subcellular localization of METTL3. Moreover, conditioned media from Hakai-silenced CRC cells modulated the expression of immune response markers in patient-derived gut immune cells. ConclusionsHakai acts as a component of the mA writer complex in CRC cells, influencing RNA methylation and the expression of immune-related genes. These findings suggest that Hakai silencing may enhance antitumour immune activity and represent a potential strategy to boost cancer immunity in colorectal cancer.

BackgroundAging is linked to hypermethylation of CpG sites on promoters and enhancers, along with loss of methylation in intergenic zones. That such changes are not necessarily a continuous process is exemplified by the extensive changes in DNA methylation during development with another significant time of change during adolescence. However, the relation between age and DNA methylation during adult life has not been systematically evaluated. In particular, potential changes in methylation trends in the same CpGs over the years that may occur with aging remain largely unexplored. MethodsHere we set out to determine the average trends by age of the CpG sites represented in the Illumina 450 platform, based on data from 2143 subjects of the age range of 20 to 80 years, compiled from 24 different cohorts. Using several mathematical procedures, we initially separated stationary probes from probes whose methylation changes with age. Among the latter, representing [~]20% of the probes, we then focused on the identification of CpG sites with switch points, i.e., a point where a stable trend of change in the age-averaged methylation is replaced by another linear trend. ResultsUsing several mathematical modeling steps, we generated a machine learning model that identified 5175 CpG sites with switch points in age-related changes in the trend of methylation over the years. Switch points reflect acceleration, deceleration or change of direction of the alteration of methylation with age. The 5175 switch points were limited to 2813 genes in three waves, 80% of which were identical in men and women. A medium-size wave was seen in the early forties, succeeded by a dominant wave as of the late fifties, lasting up to 8 years each. Waves appeared[~]4-5 years earlier in men. No switch points were detected on CpGs mapped to the X chromosome. ConclusionIn non-stationary CpG sites, concomitant switch points in age related changes in methylations can be seen in a defined group of sites and genes, which cluster in 3 age- and sex-specific waves.

PurposeHGSOC patients with BRCA1/2 mutations show HRD and PARPi sensitivity. Notably, HRD and PARPi response can occur without BRCA mutations, suggesting other factors are involved. Loss of CCDC6 function can lead to HRD and PARPi sensitivity in HGSOC cells, making CCDC6 a potential therapeutic target and biomarker. Three CCDC6 missense mutations in HGSOC prompted investigation into their impact on HRD. Analyzing CCDC6 expression, localization and HRD data in the MITO16A trial aims to clarify the CCDC6-HRD relationship in a large cohort. Experimental DesignThe biochemical and morphological effects of CCDC6 mutants on the native protein were examined using pull-down assays and immunofluorescence. HR-reporter and cell viability assays determined the impact of these mutants on HRD and PARPi sensitivity. CCDC6 histochemical score and intracellular-localization were assessed in MITO16A samples after immunostaining and digitalization. ResultsCCDC6-mutated isoforms act as dominant-negative, preventing native CCDC6 nuclear translocation, disrupting RAD51 foci and HR-repair, and increasing PARPi sensitivity. In the MITO16A patient sample set, 66 of 185 (35%) showed barely detectable CCDC6 or nuclear exclusion ("CCDC6-inactive"). CCDC6 impairment in these "CCDC6-inactive" samples was associated with HRD in 75% (30/40) of suitable samples analyzed by the RAD51 test and in 52% (34/65) of suitable samples analyzed by genomic HRD testing, even in the presence of wild-type BRCA1/BRCA2 genes. ConclusionThe association between CCDC6 inactivity and HRD, both at genomic and functional level, occurred even in presence of wild-type BRCA1/BRCA2 genes, suggesting that CCDC6 may play a crucial role in DNA repair pathways independent of these well-known genes.

BackgroundSmall intestinal neuroendocrine tumours (SI-NETs) are the most common malignancy of the small intestine and around 50% of patients present in clinic with multifocal disease. Recent investigations into the genomic architecture of multifocal SI-NETs have found evidence that these synchronous primary tumours evolve independently of each other. They also have extremely low mutational burden and few known driver genes, suggesting that epigenetic dysregulation may be driving tumorigenesis. Very little is known about epigenetic gene regulation, metabolism and ageing in these tumours, and how these traits differ across multiple tumours within individual patients. MethodsIn this study, we performed the first investigation of genome-wide DNA methylation in multifocal SI-NETs, assessing multiple primary tumours within each patient (n=79 primary tumours from 14 patients) alongside matched metastatic tumours (n=12) and normal intestinal epithelial tissue (n=9). We assessed multifocal SI-NET differential methylation using a novel method, comparing primary tumours with matched normal epithelial tissue and an enterochromaffin-enriched cell line to enrich for tumour-specific effects. This method reduced the identification of false positive methylation differences driven by cell composition differences between tumour and normal epithelial tissue. We also assessed tumour ageing using epigenetic clocks and applied metabolic predictors in the dataset to assess methylation variation across key metabolic genes. ResultsWe have identified 12,392 tumour-specific differentially methylated positions (Bonferroni corrected p<0.05) which were enriched for neural pathways. The expression levels of the genes associated with top sites were also found to be significantly altered in SI-NETs. Age acceleration was observed across SI-NETs and a variability in epigenetic age of tumours within each patient, which we believe is reflecting the order in which tumours have developed. This is supported by the correlation of age acceleration with somatic mutational count in the tumours. We have identified SI-NET associated alterations to the methylation patterns in key metabolic genes compared to matched normal tissue, which is more pronounced in metastatic tumours and tumours harbouring chromosome 18 loss of heterozygosity, indicating metabolic differences in these tumour subtypes. ConclusionsWe have identified accelerated ageing and changes to regulation of metabolic genes, alongside an epigenetic signature of multifocal SI-NETs. These findings add to our understanding of multifocal SI-NET biology and their molecular differences which may be instrumental in the development of these elusive tumours.

Multi-locus signatures of blood-based DNA methylation are well-established biomarkers for lifestyle and health outcomes. Here, we focus on two CpGs that are strongly associated with age and smoking behaviour. Imputing these loci via epigenome-wide CpGs results in stronger associations with outcomes in external datasets compared to directly measured CpGs. If extended epigenome-wide, CpG imputation could augment historic arrays and recently-released, inexpensive but lower-content arrays, thereby yielding better-powered association studies.

Post-traumatic stress disorder (PTSD) is associated with increased cardiovascular disease (CVD) risk, yet the epigenetic mechanisms underlying this link remain unclear. We investigated whether DNA methylation (DNAm) within Conserved Regions of Systemic Interindividual Variation (CoRSIVs), genomic regions showing stable within-individual, but variable between-individual methylation, mediates the association between PTSD symptom severity (PTSS) and CVD. We analyzed blood-derived DNAm from three cohorts (DNHS: discovery; GTP and NHS: replication), focusing on 7,694 CoRSIV CpGs profiled with the Illumina MethylationEPIC BeadChip. Logistic regression related CpGs to PTSS and CVD, adjusting for demographic and trauma-related covariates. CpGs nominally associated (p<0.05) with both PTSS and CVD in DNHS were then tested using causal mediation analysis. In DNHS, 27 CpGs were nominally associated with both PTSS and CVD, with seven showing nominal mediation (p<0.05). Across cohorts, six of these seven displayed mediation effects in a consistent direction in at least one replication cohort, and three CpGs showed concordant mediation directions across all three cohorts. Notably, cg07941916 (C5orf56/IRF1-AS1) and cg20545458 (intergenic) exhibited positive mediation in DNHS with the same direction in GTP, implying that higher PTSS is associated with methylation changes that correspond to higher CVD risk, whereas all mediation effects in NHS were negative, consistent with its healthier, lower-risk profile. These loci map to immune and inflammatory pathways, alongside other mediators annotated to neuronal/stress-aging and autonomic processes. Overall, DNAm variation within CoRSIVs may partially mediate PTSD-related CVD risk and nominates specific CpGs as hypothesis-generating epigenetic biomarkers that require validation in larger, ancestrally diverse longitudinal cohorts.

IntroductionSex hormones are hypothesized to drive sex-specific health disparities. Here, we study the association between sex steroid hormones and DNA methylation-based (DNAm) biomarkers of age and mortality risk including Pheno Age Acceleration (AA), Grim AA, and DNAm-based estimators of Plasminogen Activator Inhibitor 1 (PAI1), and leptin concentrations. MethodsWe pooled data from three population-based cohorts, the Framingham Heart Study Offspring Cohort (FHS), the Baltimore Longitudinal Study of Aging (BLSA), and the InCHIANTI Study, including 1,062 postmenopausal women without hormone therapy and 1,612 men of European descent. Sex hormone concentrations were standardized with mean 0 and standard deviation of 1, for each study and sex separately. Sex-stratified analyses using a linear mixed regression were performed, with a Benjamini-Hochberg (BH) adjustment for multiple testing. Sensitivity analysis was performed excluding the previously used training-set for the development of Pheno and Grim age. ResultsSex Hormone Binding Globulin (SHBG) is associated with a decrease in DNAm PAI1 among men (per 1 standard deviation (SD): -478 pg/mL; 95%CI: -614 to -343; P:1e-11; BH-P: 1e-10), and women (-434 pg/mL; 95%CI: -589 to -279; P:1e-7; BH-P:2e-6). The testosterone/estradiol (TE) ratio was associated with a decrease in Pheno AA (-0.41 years; 95%CI: -0.70 to -0.12; P:0.01; BH-P: 0.04), and DNAm PAI1 (-351 pg/mL; 95%CI: -486 to -217; P:4e-7; BH-P:3e-6) among men. In men, 1 SD increase in total testosterone was associated with a decrease in DNAm PAI1 (-481 pg/mL; 95%CI: -613 to -349; P:2e-12; BH-P:6e-11). ConclusionSHBG was associated with lower DNAm PAI1 among men and women. Higher testosterone and testosterone/estradiol ratio were associated with lower DNAm PAI and a younger epigenetic age in men. A decrease in DNAm PAI1 is associated with lower mortality and morbidity risk indicating a potential protective effect of testosterone on lifespan and conceivably cardiovascular health via DNAm PAI1. Graphic abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=141 SRC="FIGDIR/small/23285997v2_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@9d3a2corg.highwire.dtl.DTLVardef@562946org.highwire.dtl.DTLVardef@afe30corg.highwire.dtl.DTLVardef@1635f8c_HPS_FORMAT_FIGEXP M_FIG Visual representation of our main results stratified by sex There were four outcomes of interest in the rectangular shapes in the middle of this figure, Pheno-Age Acceleration (AA), Grim AA, DNAm-based PAI1, and DNAm-based leptin. We measured five hormone concentrations (testosterone, estrone, estradiol, DHEAS, and Sex Hormone Binding Globulin (SHBG)). In addition, one hormone level ratio (testosterone / estradiol) was estimated. Associations were calculated by linear mixed regression models between sex hormones and the outcomes of interests. The associations are represented by colored arrows with the lines thickness representing the strength of the association. As the association was measured mainly cross-sectional, the directionality of the association cannot be established. Hormone levels were inversely associated with epigenetic estimators of mortality risk. Abbreviations: E1: total estrone; E2: total estradiol; SHBG: Sex Hormone Binding Globulin; TotT: total testosterone; TE ratio: Total testosterone divided by total estradiol concentration C_FIG

BackgroundChronic inflammation and DNA methylation are potential mechanisms in dementia etiology. The linkage between inflammation and DNA methylation age acceleration in shaping dementia risk is understudied. We explored the association of inflammatory cytokines with cognitive impairment and whether DNA methylation age acceleration mediates this relationship. MethodsIn a subset of the 2016 wave of the Health and Retirement Study (n=3,346, age>50), we employed logistic regression to estimate the associations between each inflammatory cytokine (interleukin-6 (IL-6), C-reactive protein (CRP), and insulin-like growth factor-1 (IGF-1)), and both Langa-Weir classified cognitive impairment non-dementia and dementia, respectively. We calculated DNA methylation age acceleration residuals by regressing GrimAge on chronologic age. We tested if DNA methylation age acceleration mediated the relationship between systemic inflammation and cognitive impairment, adjusting for sociodemographic, behavioral factors, chronic conditions, and cell type proportions. ResultsThe prevalence of cognitive impairment was 16%. In the fully-adjusted model, participants with a doubling of IL-6 levels had 1.12 (95% CI: 1.02-1.22) times higher odds of cognitive impairment. Similar associations were found for CRP and IGF-1. Participants with a doubling of IL-6 levels had 0.77 (95% CI: 0.64, 0.90) years of GrimAge acceleration. In mediation analyses with each cytokine as predictor separately, 17.7% (95% CI: 7.0%, 50.9%) of the effect of IL-6 on cognitive impairment was mediated through DNA methylation age acceleration. Comparable mediated estimates were found for CRP and IGF-1. ConclusionsSystemic inflammation is associated with cognitive impairment, with suggestive evidence that this relationship is partially mediated through DNA methylation age acceleration.