Project description:In this epigenome-wide association study (EWAS), we examined the associations between PCDD, PCDF, and PCB exposures and DNA methylation. Whole blood DNA methylation was measured using Illumina EPIC arrays (n=292). We modeled lipid-adjusted toxic equivalencies (TEQs) for: ΣDioxins (sum of 28 PCDDs, PCDFs, cPCBs, and mPCBs), PCDDs, PCDFs, cPCBs, and mPCBs using robust multivariable linear regression adjusting for age, race, sex, smoking, total lipids, and estimated percentages of six blood cell types.
Project description:An Epigenome-Wide Association Study (EWAS) was conducted to compare medication-free panic disorder (PD) patients (n=89) with healthy controls (n=76) in peripheral blood samples.
Project description:Tobacco smoking alters DNA methylation profiles of immune cells which may underpin some of the pathogenesis of smoking-associated diseases. However, approaches linking smoking-driven epigenetic effects in specific immune cell types with disease risk are limited. We isolated six leukocyte subtypes, CD14+ monocytes, CD15+ granulocytes, CD19+ B cells, CD4+ T cells, CD8+ T cells, and CD56+ natural killer cells, from whole blood of healthy adult smokers and nonsmokers for epigenome-wide association study (EWAS).
Project description:Confounding due to cellular heterogeneity represents one of the foremost challenges currently facing Epigenome-Wide Association Studies (EWAS). Statistical methods leveraging the tissue-specificity of DNA methylation for deconvoluting the cellular mixture of heterogeneous biospecimens such as whole blood, offer a promising solution. However, their performance depends entirely on the library of DNA methylation markers being used as the basis for deconvolution. The objective of this study was to train and validate an algorithm for the identification of optimal DNA methylation libraries for the deconvolution of adult human whole blood. Purified granulocytes, monocytes, CD4T, CD8T, natural killer cells, and B cells from normal human subjects were purchased from AllCells LLC (Emeryville, CA). DNA extracted from purified leukocyte subtypes were mixed in predetermined proportions to reconstruct two distinct sets of white blood cell (WBC) mixtures, each consisting of six samples. An additional six whole blood (WB) samples from disease-free adult donors with available immune cell profiling data from flow cytometry were purchased from All-Cells LLC and were included in this investigation. All DNA samples were bisulfite modified using the Zymo EZ DNA Methylation kit (Irvine, CA) and profiled for DNA methylation using the Illumina HumanMethylation450 array platform.
Project description:Using HELP-Tagging, we defined the cytosine methylation profiles of hematopoietic stem/progenitor cells (CD34+) from umbilical cord blood in 29 healthy newborns. We found substantial variation of DNA methylation to occur in human CD34+ hematopoietic stem and progenitor cells from different individuals. Empirical annotation of the genome of this cell type reveals the variability to be targeted to candidate promoters and to candidate enhancer sequences of genes expressed at lower levels. The variability of DNA methylation at candidate enhancers was low for housekeeping genes but high for genes associated with leukocyte differentiation. The enrichment of DNA methylation variability at loci with intermediate methylation values, occurring at apparently “poised” enhancers, suggests cell subpopulation heterogeneity between individuals as the basis for the epigenomic variability observed. The “meta-epigenome” present even in purified cells complicates the design and interpretation of epigenome-wide association studies, but also allows insights into the gene expression characteristics and the number of cell types comprising the cell population analyzed. One Sentence Summary: Variability in epigenomic patterns between different individuals occurs predominantly at promoters and enhancers, reflecting cell subpopulation heterogeneity.
