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

Abstract

Background and purpose: Remote ischemic conditioning (RIC) is a phenomenon in which short periods of nonfatal ischemia in 1 tissue confers protection to distant tissues. Here we performed a longitudinal human pilot study in patients with aneurysmal subarachnoid hemorrhage undergoing RIC by limb ischemia to compare changes in DNA methylation and transcriptome profiles before and after RIC.

Methods: Thirteen patients underwent 4 RIC sessions over 2 to 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 and differential methylation using an intraindividual paired study design and then overlapped the differential expression and differential methylation results for analyses of functional categories and protein-protein interactions.

Results: We observed 164 differential expression genes and 3493 differential methylation 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 coexpressed genes (P<0.00001).

Conclusions: Gene expression and DNA methylation changes in aneurysmal subarachnoid hemorrhage patients undergoing RIC are involved in coordinated cell cycle and inflammatory responses.

Keywords: DNA methylation; aneurysm; genomics; preconditioning; subarachnoid hemorrhage; transcriptome.

© 2015 American Heart Association, Inc.

Figures

Figure 1

A schematic overview of study design and results.

Figure 2

The differentially expressed (DE) genes between the aSAH baseline and a week after RIC treatment. Red dots indicate DE genes with an FDR

Figure 3

Protein-protein interactions (PPIs) of the 103 differentially expressed (DE) genes using String. We observed a statistically significant (P

Figure 4

Co-expression analysis of the 14 mitotic cell cycle genes identified in the Protein-protein interactions (PPIs) and functional enrichment analyses.