Remote Ischemic Conditioning Alters Methylation and Expression of Cell Cycle Genes in Aneurysmal Subarachnoid Hemorrhage

Background and purposeRemote ischemic conditioning (RIC) is a phenomenon in which short periods of non-fatal ischemia in one tissue confers protection to distant tissues. Here we performed a longitudinal human pilot study in patients with aneurysmal subarachnoid hemorrhage (aSAH) undergoing RIC by limb ischemia to compare changes in DNA methylation and transcriptome profiles before and after RIC.MethodsThirteen patients underwent 4 RIC sessions over 2–12 days after rupture of an intracranial aneurysm. We analyzed whole blood transcriptomes using RNA sequencing and genome-wide DNA methylomes using reduced representation bisulfite sequencing, both before and after RIC. We tested differential expression (DE) and differential methylation (DM) using an intra-individual paired study design, and then overlapped the DE and DM results for analyses of functional categories and protein-protein interactions.ResultsWe observed 164 DE genes and 3,493 DM CpG sites after RIC, of which 204 CpG sites overlapped with 103 genes, enriched for pathways of cell cycle (P<3.8×10−4) and inflammatory responses (P<1.4×10−4). The cell cycle pathway genes form a significant protein-protein interaction network of tightly co-expressed genes (P<0.00001).ConclusionsGene expression and DNA methylation changes in aSAH patients undergoing RIC are involved in coordinated cell cycle and inflammatory responses