Transcriptome analysis of peripheral blood mononuclear cells from stroke survivors

Background and purpose: The simultaneous analysis of thousends of different RNA species by GeneChip analysis (expression profiling) enables the study of functionally coordinated genetic pathways rather than the analysis of single genes. In this study we aimed to identify differences in gene expression in circulating white blood cells from stroke survivors and healthy control subjects.

Methods: RNA from peripheral blood mononuclear cells (PBMCs) of 15 stroke survivors and 15 healthy referent subjects was analyzed with GeneChips. Gene expression was studied either immediately after blood sampling or after 2 hours in vitro endotoxin stimulation.

Results: Detectable amounts of transcripts in PBMCs were found in 10124 out of 22283 probe sets of the Affymetrix U133A GeneChip. Endotoxin stimulation induced dramatic changes in the transcriptome with 22 genes more than tenfold up-regulated and 6 genes over tenfold down-regulated. None of the probe sets showed significantly different values in stroke survivors and healthy subjects, but the study of ontologic gene groups revealed differences between stroke survivors and patients. Upon endotoxin stimulation genes involved in inflammatory response, as well as genes involved in acute stroke genes showed differential expression in stroke survivors and controls. In non-stimulated cells differential gene regulation was only observed for a group of genes recently identified as stroke-relevant by Tang et al (2006). Our data suggest mild up-regulation of S100P, CDA, IL1R2, MMP9 and F5 in the cirulation of stroke survivors and mild down regulation of Hist2H2AA.

Conclusions: The PBMC transcriptomes from stroke survivors and control subjects are very similar. However, the analysis of ontologic gene groups revealed significant differences between cells from stroke survivors and controls. A group of genes identified as very early responders to ischemic stroke (by Tang et al 2006) was found differentially expressed in our sample of stroke survivors. We therefore think that these genes are not involved in the very early response on brain ischemia, but in the pre-ischemic risk profile.