Abstract 526: A Transcriptomic Analysis of Cardiac Myofibroblasts Reveals Novel Anti-fibrotic and Immunomodulatory Genes Modulated by CDC-Derived Exosomes

Abstract

Background: Cardiac fibroblasts are the most prevalent cell in the heart and play an important role in both the healthy and diseased myocardium. Following myocardial infarction, TGF-β secretion promotes a phenotype transition of fibroblasts to activated myofibroblasts. We have previously shown that CDC-derived exosomes promote cardiomyocyte proliferation and survival, stimulate angiogenesis, and polarize cardiac macrophages to a unique Arg1-high phenotype. We hypothesized that CDC-derived exosomes modulate the gene expression of myofibroblasts to attenuate fibrosis in the remodeling heart. Methods: We took a genomics-based approach to investigate CDC-exosome mediated differential gene expression and regulation of operant signaling pathways in TGF-β induced ventricular myofibroblasts. Cardiac fibroblasts were isolated from C57BL/6 mice (n=3) using a Langendorff-free method of in situ enzymatic dissociation. Cells were plated at 1x10 5 cells/mL, serum depleted to induce cell cycle arrest and exposed to 4 different conditions: media alone, TGF-β (4 ng/ml) “myofibroblasts”, CDC-exosomes (20 μg/ml), or TGF-β and CDC-exosomes. After 24 hours, RNA was extracted and analyzed by RNA-seq. Results/Conclusions: Gene ontology analysis showed attenuation of a pro-fibrotic gene expression profile in the TGF-β + CDC-exo group relative to TGF-β treatment alone. Genes involved in blunting of the pro-fibrotic response ( Mmp14 and Qsox1) , as well those implicated in attenuating the transition of fibroblasts to myofibroblasts ( Gsto1 ) were also upregulated in CDC-exosome treated myofibroblasts (edgeR; FDR-corrected p<0.05). Interesting, we found a highly significant enrichment of genes involved in macrophage migration ( Kars , Mmp14 , and Tnfsf18 ) in the CDC-exosome treated myofibroblasts relative to the TGF-β group (GO:1905523, p=8.42x10 -6 ). These data suggest active cross talk between myofibroblasts and macrophages and highlight a novel immunomodulatory role of CDC-derived exosomes on myofibroblasts post MI.