Transcriptome signature of ventricular arrhythmia in dilated cardiomyopathy reveals increased fibrosis and activated TP53

Highlights

• About 1:3 of dilated cardiomyopathy patients experience ventricular tachycardia.

• Our understanding of the biological basis of these arrhythmias is incomplete.

• RNA-seq demonstrates discrete arrhythmia and non-arrhythmia expression profiles.

• These expression signatures are enriched for distinct biological pathways.

• TP53 and TGFβ1 pathways distinguish arrhythmia and non-arrhythmia cohorts.

Abstract

Aims

One-third of DCM patients experience ventricular tachycardia (VT), but a clear biological basis for this has not been established. The purpose of this study was to identify transcriptome signatures and enriched pathways in the hearts of dilated cardiomyopathy (DCM) patients with VT.

Methods and results

We used RNA-sequencing in explanted heart tissue from 49 samples: 19 DCM patients with VT, 16 DCM patients without VT, and 14 non-failing controls. We compared each DCM cohort to the controls and identified the genes that were differentially expressed in DCM patients with VT but not without VT. Differentially expressed genes were evaluated using pathway analysis, and pathways of interest were investigated by qRT-PCR validation, Western blot, and microscopy. There were 590 genes differentially expressed in DCM patients with VT that are not differentially expressed in patients without VT. These genes were enriched for genes in the TGFß1 and TP53 signaling pathways. Increased fibrosis and activated TP53 signaling was demonstrated in heart tissue of DCM patients with VT.

Conclusions

Our study supports that distinct biological mechanisms distinguish ventricular arrhythmia in DCM patients.

Introduction

Cardiac arrhythmias frequently complicate dilated cardiomyopathy (DCM), causing physical symptoms, a need for medications and/or device therapy, and sudden cardiac death [1]. In DCM, life-threatening arrhythmias can present early in disease [2], and approximately one-third of patients experience frequent ventricular arrhythmias, which may occur independent of left ventricular (LV) dysfunction [3]. Although arrhythmia-prone patients can be identified and stratified clinically once arrhythmias develop, there is a significant knowledge gap in understanding the biological mechanisms that contribute to ventricular arrhythmias in arrhythmogenic DCM patients.

Molecular and histological studies of human heart tissue from DCM patients with and without history of ventricular arrhythmias showed that patients with a positive history had increased hypertrophy, evidence of oxidative stress, and fibrosis. Microarray analysis showed differences in gene expression that included increased expression of select genes encoding extracellular matrix proteins (FGF18, COL4A2, COL12A1) and ion channels (KCNN2, TRPM7); a formal analysis for enrichment of differentially expressed genes in key biological pathways has not been performed and prior results were not compared against non-failing (NF) controls [4].

We and others have previously showed that although there is a common heart failure gene expression signature for heart failure, there are also distinct gene expression signatures that distinguish DCM from ischemic cardiomyopathy that suggest distinct disease mechanisms [[5], [6], [7], [8], [9]]. Here, we hypothesized that within DCM, sub-phenotypic gene expression signatures exist that distinguish the arrhythmogenic DCM (aDCM) from the non-arrhythmogenic DCM (naDCM) state. To test this hypothesis, we performed RNA-sequencing (RNA-seq) on 49 explanted human hearts and used a multi-analytic approach to discern aDCM- and naDCM-specific expression profiles. Using pathway analysis, our results support that distinct disease mechanisms exist within DCM that separate arrhythmogenic and non-arrhythmogenic biological sub-phenotypes of DCM, including activation of TGFβ1 and TP53 signaling.