Abstract 13522: RNA Sequencing Identifies Differential Expression of ICAM1, NOS3, And BLVRB in Peripheral Blood of Patients after Left Ventricular Assist Device Insertion
Left ventricular assist devices (LVADs) have therapeutic benefit for patients with end stage heart failure. Mechanical unloading of the heart via continuous flow LVADs significantly alters systemic hemodynamics and is thought to influence endothelial function and nitric oxide metabolism. We tested the hypothesis that LVAD support alters the expression of genes involved in nitric oxide metabolism, heme catabolism, and inflammation in peripheral blood of patients with end stage heart failure. Nine patients (8 male, 1 female) with severe heart failure (6 ischemic, 3 non-ischemic) were selected for study. Blood samples were drawn prior to (t0) and 7 days after (t1) LVAD insertion. Illumina RNAseq technology was used to characterize the whole blood transcriptome of all patients at each time point. Sequences for each patient sample were aligned to human genomic reference using Tophat. Raw FPKM values were then generated using Cufflinks followed by Cuffmerge to create a common gtf reference. Cuffdiff was run on patient t0, t1 samples to obtain the final FPKM values for each patient time point. We then selected 30 well characterized genes associated with nitric oxide metabolism, heme catabolism, and inflammation to analyze. A paired t-test was employed to compare expression levels (FKPM, fragments per kilobase of exon model per million mapped reads) before and after LVAD insertion. To control for multiple hypothesis tests, q-values were calculated using the false discovery rate (FDR) approach and chose a cutoff of 0.10 for statistical significance. Three genes, intercellular adhesion molecule 2 (ICAM2), nitric oxide synthase 3 (NOS3), and biliverdin reductase B (BLVRB) demonstrated statistically significant changes in expression between t0 and t1. ICAM2 expression decreased 0.75 fold one week after LVAD implant (p = 0.00048, q= 0.027). NOS3 expression also decreased 0.47 fold (p = 0.0067, q = 0.085), and BLVRB increased 2.4 fold (p = 0.007, q = 0.08). Increased BLVRB expression would be expected with increased hemolysis that is known to occur after LVAD placement. To our knowledge this is the first study to look at circulating transcript expression one week post LVAD placement. Studies are on-going to assess cell type, and protein expression with ELISA.
- © 2012 by American Heart Association, Inc.