ATAC-Seq of healthy and IBD blood samples

PBMCs from blood samples of 9 age- and gender-matched healthy subjects and 25 IBD patients were isolated through a Ficoll density gradient and used to isolate live CD4 T cells through a magnetic cell isolation kit (Miltenyi Biotec). Twelve thousand live CD4 T cells were then used to prepare ATAC-Seq libraries. Briefly, crude nuclei of live CD4+ T cells were treated with Tagment DNA buffer and Tagment DNA Enzyme (Nextera DNA Library Prep Kit, Illumina), and then the DNA was purified by MinElute PCR Purification Kit (Qiagen). Transposed DNA fragments were amplified using specific adapters followed by purification with MinElute PCR Purification Kit (Qiagen). Fragments from 240-360pb were selected in the PippinHT system (Sage Science). The quality of the library and its DNA concentration were assessed by Bioanalyzer instruments (Agilent Technologies) and ultimately submitted for sequencing using Illumina HiSeq 2500 sequencer, V4 chemistry.EGA study EGAS00001007343