Major surgery induces acute changes in DNA methylation associated with immune response pathways

Using a longitudinal study design, we quantified DNA methylation across the genome in a cohort of 30 elderly patients (average age = 77.9 years (range 62-91)) undergoing major surgery (either elective colorectal surgery, elective hip replacement surgery, and emergency hip surgery following fracture). From each individual, detailed clinical blood measures were collected and DNA methylation was profiled using the Illumina Human Methylation 450 array (g450K arrayh) (Illumina Inc. San Diego, California) in DNA samples isolated from purified PBMCs collected at three time-points: i) immediately before surgery (baseline (BL)), ii) in the morning of post-operative day 1 (POD1) and iii) between post-operative day 4 and 7 (POD4/7) prior to discharge from hospital. Using a longitudinal study design, we quantified DNA methylation across the genome in a cohort of 30 elderly patients undergoing major surgery. DNA methylation was profiled using the Illumina Human Methylation 450 array.