Project description:Extensive epigenetic remodelling takes place during early life; however, the alterations of DNA methylation that occur during this period have not been sufficiently addressed by longitudinal studies. We made use of the most recent Illumina MethylationEPIC Beadchip platform to characterize genome-wide DNA methylation changes observed through the first 10 years of life in longitudinal blood samples of 11 subjects. We described numerous changes during the first 5 years, while many less alterations in the following 5 year period. Interestingly, we identified a subset of persistent DNA methylation changes of considerable magnitude along the first 10 years of life. Moreover, our data demonstrated that genes that suffer simultaneous hyper- and hypomethylation are functionally different from genes that are exclusively hyper- or hypomethylated. Furthermore, our results evidence that enhancer-associated methylation changes are different for the gain or loss of methylation. throughout hematopoietic maturation by analyzing multiple hematopoietic cell types at different developmental stages. We identified a plethora of DNA methylation changes that occur during human hematopoietic differentiation. Interestingly, we observed that T lymphocytes display a substantial enhancement of de novo CpG hypermethylation as compared to other hematopoietic cell populations.
Project description:Background: Early life epigenetic programming influences adult health outcomes. Moreover, DNA methylation levels have been found to change more rapidly during the first years of life. Our aim was the identification and characterization of the CpG sites that are modified with time during the first years of life. We hypothesize that these DNA methylation changes would lead to the detection of genes that might be epigenetically modulated by environmental factors during early childhood and which, if disturbed, might contribute to susceptibility to diseases later in life. Methods: The study of the DNA methylation pattern of 485577 CpG sites was performed on 30 blood samples from 15 subjects, collected both at birth and at 5 years old, using Illumina® Infinium 450 k array. To identify differentially methylated CpG (dmCpG) sites, the methylation status of each probe was examined using linear models and the Empirical Bayes Moderated t test implemented in the limma package of R/Bioconductor. Surogate variable analysis was used to account for batch effects. Results: DNA methylation levels significantly changed from birth to 5 years of age in 6641 CpG sites. Of these, 36.79 % were hypermethylated and were associated with genes related mainly to developmental ontology terms, while 63.21 % were hypomethylated probes and associated with genes related to immune function. Conclusions: Our results suggest that DNA methylation alterations with age during the first years of life might play a significant role in development and the regulation of leukocyte-specific functions. This supports the idea that blood leukocytes experience genome remodeling related to their interaction with environmental factors, underlining the importance of environmental exposures during the first years of life and suggesting that new strategies should be take into consideration for disease prevention. Longitudinal study including 15 samples
Project description:We measured the DNA methylation levels at ~800,000 CpG sites from ethnically admixed children in CBMCs at birth and PBMCs age 7 to study the longitudinal dynamics of methylation marks. We found that self-reported race-dependent methylation levels were conserved over time, which helped to suggest that blood methylation levels are robust to environmental exposures during the first 7 years of life.
Project description:Background: Early life epigenetic programming influences adult health outcomes. Moreover, DNA methylation levels have been found to change more rapidly during the first years of life. Our aim was the identification and characterization of the CpG sites that are modified with time during the first years of life. We hypothesize that these DNA methylation changes would lead to the detection of genes that might be epigenetically modulated by environmental factors during early childhood and which, if disturbed, might contribute to susceptibility to diseases later in life. Methods: The study of the DNA methylation pattern of 485577 CpG sites was performed on 30 blood samples from 15 subjects, collected both at birth and at 5 years old, using Illumina® Infinium 450 k array. To identify differentially methylated CpG (dmCpG) sites, the methylation status of each probe was examined using linear models and the Empirical Bayes Moderated t test implemented in the limma package of R/Bioconductor. Surogate variable analysis was used to account for batch effects. Results: DNA methylation levels significantly changed from birth to 5 years of age in 6641 CpG sites. Of these, 36.79 % were hypermethylated and were associated with genes related mainly to developmental ontology terms, while 63.21 % were hypomethylated probes and associated with genes related to immune function. Conclusions: Our results suggest that DNA methylation alterations with age during the first years of life might play a significant role in development and the regulation of leukocyte-specific functions. This supports the idea that blood leukocytes experience genome remodeling related to their interaction with environmental factors, underlining the importance of environmental exposures during the first years of life and suggesting that new strategies should be take into consideration for disease prevention.
Project description:Children develop rapidly during the first years of life, and understanding the different sources and levels of variation in serum proteome of young children is important when using serum proteins as markers for childhood diseases. We have performed label/free quantitative proteomics for longitudinal serum samples collected from a group of children during the first years of life.
Project description:Fifteen-year-old adolescents (N = 109) in a longitudinal study of child development were recruited to examine differences in DNA methylation in relation to parent reports of adversity during the adolescents’ infancy and preschool periods. Microarray technology applied to 28,000 cytosine–guanine dinucleotide sites within DNA derived from buccal epithelial cells showed differential methylation among adolescents whose parents reported high levels of stress during their children’s early lives. Maternal stressors in infancy and paternal stressors in the preschool years were most strongly predictive of differential methylation, and the patterning of such epigenetic marks varied by children’s gender. To the authors’ knowledge, this is the first report of prospective associations between adversities in early childhood and the epigenetic conformation of adolescents’ genomic DNA.
Project description:The prevalence of respiratory allergy in children is increasing. Epigenetic changes (e.g. DNA methylation) are plausible underlying molecular mechanisms. Longitudinal birth cohorts are instrumental to study the relation between early-life environmental factors and the development of complex diseases. Our AXA Research Fund and Cefic-LRI supported project explores the hypothesis that chemical exposures during pregnancy can influence the immune system and development of allergy in children. Questionnaire data, as well as cord blood, plus blood and saliva samples at age 11 years, were collected in substudies of two longitudinal birth cohorts in Belgium (FLEHS1 & FLEHS2) and analyzed with Illumina Methylation 450K BeadChips as well as gene targeted iPLEX MassArrays analysis. The project aims to answer the following questions: 1) can we identify specific changes in epigenetic modifications on DNA from allergic compared to not-allergic children; 2) are these allergy-related epigenetic changes a result of chemical exposure during pregnancy; and 3) did the early life exposures leave an epigenetic “mark” that is maintained through childhood. If chemicals exposures and resulting predictive markers of allergic diseases can be detected early, prevention strategies, particularly in children or before pregnancy, could be developed.
Project description:Fifteen-year-old adolescents (N = 109) in a longitudinal study of child development were recruited to examine differences in DNA methylation in relation to parent reports of adversity during the adolescents’ infancy and preschool periods. Microarray technology applied to 28,000 cytosine–guanine dinucleotide sites within DNA derived from buccal epithelial cells showed differential methylation among adolescents whose parents reported high levels of stress during their children’s early lives. Maternal stressors in infancy and paternal stressors in the preschool years were most strongly predictive of differential methylation, and the patterning of such epigenetic marks varied by children’s gender. To the authors’ knowledge, this is the first report of prospective associations between adversities in early childhood and the epigenetic conformation of adolescents’ genomic DNA. Genomic DNA was extracted from 109 Buccal DNA samples, bisulphite converted and hybridized, along with 4 technical replicates to the Illumina Infinium HumanMethylation27 Beadchip v1.2 for genome wide DNA methylation profiling. Processed signal intensity data and Detection Pvalues for individual replicates of Samples 006 (reps a,b), 099 (reps a,b,c), 106 (reps a,b) reported in the supplementary file "processed_individual reps.txt."
Project description:Early life social experiences are believed to confer persistent effects on individual’s biology and subsequent functioning and health. Using a diverse, longitudinal community sample of 178 children, we show that three different types of early life social experience: family income, parental education, and family psychosocial adversity, each predict DNA methylation within buccal epithelial cells. Each predictor was significantly associated with DNA methylation within a unique set of genomic CpG sites, with income showing the greatest number of associations. Findings were independently verified using pyrosequencing. Our results provide evidence for longitudinal associations between early life social environment and variation in DNA methylation during childhood, after adjusting for genetic ancestry and self-reported ethnic minority status. Gene ontology analyses of top, differentially methylated CpG sites point to genes serving immune and developmental regulation functions, suggesting potential pathways for the biological embedding of early life stress and its association with later development and health.
Project description:Genome-wide DNA methylation profiling of DNA extracted from dried blood spots from preterm and term subjects using longitudinal samples collected at birth and 18 years of age. Infinium HM450 arrays were used to measure methylation at 347,789 autosomal CpGs. DNA was analysed from individuals at birth and 18-years and included 12 preterm and 12 term controls. Bisulphite converted DNA from the 48 samples were hybridised to the Illumina Infinium 450K Human Methylation Beadchip