Epigenome-scale comparison of DNA methylation between blood leukocytes and bronchial epithelial cells

Aim: Agreement in DNA methylation (DNAm) at the genome scale between blood leukocytes (BL) and bronchial epithelial cells (BEC) is unknown. We examine as to what extent DNAm in BL is comparable with that in BEC and serves as a surrogate for BEC. Materials & methods: Overall agreement (paired t-tests with false discovery rate adjusted p > 0.05) and consistency (Pearson's correlation coefficients >0.5) between two tissues, at each of the 767,412 CpGs, were evaluated. Results: We identified 247,721 CpGs showing overall agreement and 47,371 CpGs showing consistency in DNAm. Identified CpGs are involved in certain immune pathways, indicating the potential of using blood as a biomarker for BEC at those CpGs in lower airway-related diseases. Conclusion: CpGs showing overall agreement and those without overall agreement are distributed differently on the genome.