Abstract
PurposeThe mechanisms for persistent and progressive loss of myocardial function in advanced heart failure (HF) remain incompletely characterized. In the current study, we sought to determine the impact of TGF-β on fibroblasts transcriptional profiles and assess if exosomes from TGF-β treated fibroblasts could induce a heart failure phenotype in co-cultured cardiomyocytes. MethodNormal heart fibroblasts were treated with TGF-β with a final conc. of 2.5 ng/ml in serum free media. HF fibroblasts were also obtained from patients undergoing implantation of left ventricular assist devices. Exosomes were collected using three-step ultracentrifugation. Cardiomyocytes were co-cultured with exosomes from TGF-β-treated, HF and control fibroblasts. RNA was extracted from the fibroblasts, exosomes, and the cardiomyocytes for a targeted panel of genes using Ion AmpliSeq. Fibroblast function was evaluated by collagen gel contraction. ResultsFibroblasts treated with TGF-β differentially express 21 of the 140 genes in our targeted panel. These fibroblasts exhibit enhanced collagen gel contraction similar to HF fibroblasts. Fifty of these targeted genes were also differentially expressed in fibroblast exosomes. Pathway analysis of these transcriptional changes suggest hypertrophic signaling to cardiac muscle. Cardiomyocytes, co-cultured with exosomes from TGF- β treated fibroblasts or heart failure patients, differentially expressed 40 genes compared to controls. Cardiomyocytes co-cultured with exosomes of TGF-β treated fibroblasts induced a molecular phenotype similar to cardiomyocytes co-cultured with exosomes from HF fibroblasts. These changes involve contractile proteins, adrenergic receptors, calcium signaling, metabolism and cell renewal. ConclusionTGF-β induces broad transcriptional changes in fibroblasts as well as their exosomes. These exosomes induce a heart failure phenotype in cardiomyocytes. Exosome signaling from fibroblasts likely contributes to disease progression in heart failure.
Highlights
Heart failure is a major cause of morbidity and mortality in the United States
In this study we determined the impact of TGF-β on transcriptional profiles of fibroblasts and their exosomes
We evaluated the impact of TGF-β on fibroblast function relative to heart failure and assessed the ability of exosomes from fibroblasts to alter myocyte phenotype
Summary
Heart failure is a major cause of morbidity and mortality in the United States. There are approximately 6.0 million Americans living with heart failure representing about 2.8% of the adult US population [1]. There are over 1 million hospitalizations for acutely decompensated heart failure every year, and it remains the largest federal Medicare expenditure. Heart failure can be genetic but is caused by numerous disease processes, including coronary artery disease, alcohol, viruses and thyroid disease [2]. Heart failure is characterized by transcriptional changes in myocytes that contribute to contractile dysfunction as well as an increase in fibrosis contributing to diastolic dysfunction and arrhythmia risk [3, 4, 5, 6, 7, 8]. Little is known about the interactions between cardiomyocytes and myocardial fibroblasts in heart failure
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