Abstract 18041: RNAseq Identifies Differential Expression of Platelet Transcripts Between Hyper and Hypo-Aggregation to Collagen

Abstract

Background: Platelet aggregation plays an important role in the pathogenesis of myocardial infarction, and high platelet aggregability is associated with increased risk of events. We hypothesized that inter-individual variability in platelet function is associated with differences in the mRNA transcripts found in platelets from hyper-aggregators and hypo-aggregators. Methods: Ten individuals with family history of early onset coronary artery disease were enrolled. Individuals were divided into hyper- and hypo-aggregators based on maximal aggregation to collagen using whole blood impedance aggregometry. RNA was extracted from leukocyte-depleted platelet-rich plasma and approximately 70 million 100bp paired-end reads per sample were obtained using an Illumina HiSeq 2500. RNA-seq analysis was performed using Bowtie/TopHat/Cufflinks software pipeline. Genes with expression ≥ 0.3 fragments per kilobase of transcript per million reads (FPKM) were considered to be expressed. Genes with ≥ 2-fold change in expression on log2 scale and FDR<0.1 were considered to be significantly differentially expressed. Results: Study sample consisted of 2 females and 3 males in each group. Among the 12,105 expressed genes, the most highly expressed nonubiquitous genes included GPX1, PPBP, PF4, & TUBB1, confirming our methodologies. Hyper-aggregability was associated with up-regulation of 69 genes (such as MTRNR2L1 [anti-apoptotic], DEFA1 [innate immune response], and MYL4 [myosin light chain]). On the other hand, 50 genes were significantly down-regulated in hyper-aggregators (such as CCL3L1 [chemotactic for lymphocytes], CXCL5 [chemokine], and TUBB2A[beta-tubulin]). Gene ontology enrichment analysis found that genes related to innate immune response were up-regulated while genes related to B- and T-lymphocyte regulation were down-regulated in hyper-aggregators. Conclusion: RNA-seq and gene ontology analyses found that hyper- and hypo-aggregators have significant differences in gene expression. Increased expression of innate immune pathway genes in hyper-aggregators highlights the relationship of inflammation with increased platelet aggregation and suggests a role of platelets in innate immune response.