Bacterial Infection Remodels the DNA Methylation Landscape of Human Dendritic Cells (Bisulfite-Seq)

Peripheral blood mononuclear cells (PBMCs) were isolated from buffy coats by Ficoll-Paque centrifugation. Blood monocytes were then purified from PBMCs by positive selection with magnetic CD14 MicroBeads (Miltenyi Biotech). Pure monocytes were cultured for 5 days in RPMI 1640 (Invitrogen) supplemented with 10% heat-inactivated FCS (Dutscher), L-glutamine (Invitrogen), GM-CSF (20 ng/mL; Immunotools), and IL-4 (20 ng/mL; Immunotools). Cell cultures were fed every 2 days with complete medium supplemented with the cytokines previously mentioned. Before infection, we systematically checked the differentiation/activation status of the monocyte-derived DCs by flow cytometry, using antibodies against CD1a, CD14, CD83, and HLA-DR. Only samples presenting the expected phenotype for non-activated DCs – CD1a+, CD14-, CD83-, and HLA-DRlow – were used in downstream experiments. Dendritic cells (DCs) were infected with a Mycobacterium tuberculosis (MTB) strain expressing green-fluorescent protein (H37Rv) for 18 h at a multiplicity of infection of 1-to-1. Full details can be found in Barreiro et al. (2012). Overall design: DNA methylation profiles of 6 non-infected and 6 MTB-infected dendritic cell samples.