Apremilast improves cardiomyocyte cohesion and arrhythmia in different models for arrhythmogenic cardiomyopathy

Abstract

Background Arrhythmogenic cardiomyopathy (ACM) is a genetically inherited desmosome heart disease leading to life-threatening arrhythmias and sudden cardiac death. Currently, ACM treatment paradigms are merely symptom targeting. Recently, apremilast was shown to stabilize keratinocyte adhesion in the desmosomal disease pemphigus vulgaris. Therefore, this study investigated whether apremilast can be a therapeutic option for ACM. Methods Human induced pluripotent stem cells from a healthy control (hiPSC) and an ACM index patient (ACM-hiPSC) carrying a heterozygous desmoplakin (DSP) gene mutation (c.2854G > T, p.Glu952Ter), confirmed by whole exome sequencing (WES), were established. Cyclic-AMP ELISA, dissociation assay, immunostaining, and Western blotting analyses were performed in human iPSC-derived cardiomyocytes (hiPSC-CMs), murine HL-1 cardiomyocytes, and cardiac slices derived from wild-type (WT) mice, plakoglobin (PG, Jup) knockout (Jup−/−) (murine ACM model) or PG Serine 665 phosphodeficient (JUP-S665A) mice. Microelectrode array (MEA) analyses in ventricular cardiac slices and Langendorff heart perfusion were performed to analyze heart rate variability and arrhythmia. Results ACM-hiPSC derived cardiomyocytes (ACM-hiPSC-CMs) revealed a significant loss of cohesion, which was rescued by apremilast. Further, treatment with apremilast strengthened basal cardiomyocyte cohesion in HL-1 cells and WT murine cardiac slices, paralleled by phosphorylation of PG at Serine 665 in human and murine models. In HL-1 cells, apremilast in addition activated ERK1/2, inhibition of which abolished apremilast-enhanced cardiomyocyte cohesion. Further, dissociation assays in slice cultures from JUP-S665A and Jup−/− mice revealed that PG is crucial for apremilast's effects. Additionally, apremilast reduced arrhythmic events in ventricular cardiac slices and Langendorff-perfused hearts. Conclusion Apremilast improves cardiomyocyte cohesion and reduces arrhythmia in different models of ACM, suggesting a novel therapeutic strategy for this disease.

1. Introduction

Arrhythmogenic cardiomyopathy (ACM) is an uncommon hereditary heart condition that can lead to sudden cardiac death (SCD), particularly among young athletes (Corrado, Basso et al. [9], Corrado, Link et al. [10]. The estimated prevalence of this condition ranges from 1 in 1000 to 1 in 5000 individuals (Peters, Trummel et al. [37], Groeneweg, Bhonsale et al. [4]). Notably, SCD can even occur in the initial concealed phase without observable structural changes in the ventricles, and it may be the first manifestation of the disease in approximately 5–10% of cases (Peters, Trummel et al. [37], Bhonsale, Groeneweg et al. [4], Groeneweg, Bhonsale et al. [4]). Approximately 60% of ACM patients carry pathogenic variants in genes encoding desmosomal proteins encompassing both plaque proteins like plakophilin 2 (PKP2), desmoplakin (DSP), and plakoglobin (JUP), as well as cadherin-type adhesion molecules such as desmoglein 2 (DSG2) and desmocollin 2 (DSC2) [14], Marcus, McKenna et al. [30], Vimalanathan, Ehler et al. [55], Costa, Cerrone et al. [12], Gasperetti, Carrick et al. [19]. Hence, ACM is recognized primarily as a desmosomal disease.

Current therapeutic options for ACM include lifestyle changes, anti-arrhythmic drugs, catheter ablation, implantable cardioverter-defibrillators, and ultimately heart transplantation for refractory cases. However, these approaches are symptomatic and do not address the underlying molecular defects. Recent advancements suggest that enhancing intracellular cAMP could be beneficial in treating desmosomal diseases, offering a potential targeted therapy. In this context, apremilast, a phosphodiesterase-4 inhibitor, has been shown to stabilize keratinocyte adhesion in pemphigus vulgaris, another desmosomal disease. This study investigates whether apremilast can similarly improve cardiomyocyte cohesion and reduce arrhythmia in models of ACM, potentially providing a novel treatment strategy.