Abstract 11474: Pro-Inflammatory Environment and Oxidized LDL Convert “Early” Endothelial Progenitor Cells Into Antigen Presenting Cells With Distinct Gene Expression Profiles
Background: We previously found that exposure to pro-inflammatory environment or oxidized-LDL (oxLDL), an atherogenic autoantigen, converts human peripheral blood-derived “early” endothelial progenitor cells (EPCs) into functional antigen presenting cells (APCs). In the present work we assessed whether exposure to the two distinct environments causes specific changes in gene expression potentially affecting their function as pro-atherogenic cells.
Methods and Results: EPCs were derived by culturing mononuclear cells of human healthy donors into EGM-2 for 7 days. EPCs were primed for 3 days with GM-CSF and IL4 (10 ng/ml) in 10% FBS containing medium, followed by culture in 10% FBS, IL1β and TNFα (10ng/ml) [APC], or in 1% FBS and oxLDL (80ng/ml) [APCox] containing media. EPCs, APCs and APCox RNA (n=6) was hybridized onto HumanHT-12 v4 microarrays (Illumina). Data were pre-processed (VST and RSN) and genes were filtered-out when the 25th percentile of intensities had a P-value detection level <0.01 and the log-ratio variation had a P>0.01. The ANOVA F-test identified 2571 genes differentially expressed among groups with a significance level P<0.001 (FDR<5‰). Pairwise comparisons (alpha=0.01) revealed that 1157 genes were up- and 1103 were down-regulated in APCs vs. EPCs, 902 were up- and 952 were down-regulated in oxAPCs vs. EPCs, and 590 were up- and 618 were down-regulated in oxAPCs vs. APCs. Gene Ontology set expression comparisons (LS/KS permutation test and Efron-Tibshirani’s GSA maxmean test; P=0.005) were then performed to assess gene set expression changes related to specific functions. Results showed a significant increase in gene sets expression related to innate immunity, cytokine production/response and lymphocyte activation in APCs vs. EPCs (24 gene sets) and oxAPCs vs. EPCs (6 gene sets). A reduced immunomodulatory and cholesterol metabolism gene sets expression in oxAPCs vs. APCs (64 gene sets) was observed. Finally, 3 gene sets related to TNFalpha signaling were upregulated in oxAPCs.
Conclusions: Conversion of human EPCs into APCs is associated to robust modifications in gene expression profile. This establishes the basis for a functional divergence of pro-angiogenic cells primed in an inflammatory vs. an atherogenic environment.
- © 2013 by American Heart Association, Inc.