Novel insights in the pathomechanism of Brugada syndrome and fever-related type 1 ECG changes in a preclinical study using human induced pluripotent stem cell-derived cardiomyocytes

Y. Li (Mannheim)¹, H. Dinkel (Mannheim)¹, D. Pakalniskyte (Mannheim)¹, A. Busley (Göttingen)², L. Cyganek (Göttingen)³, R. Zhong (Mannheim)¹, F. Zhang (Mannheim)¹, Q. Xu (Mannheim)¹, L. Maywald (Mannheim)¹, A. Aweimer (Bochum)⁴, M. Huang (Mannheim)¹, Z. Liao (Mannheim)¹, Z. Meng (Mannheim)⁵, Z. Yang (Mannheim)¹, L. Qiao (Mannheim)¹, A. Mügge (Bochum)⁶, X. Zhou (Mannheim)⁵, I. Akin (Mannheim)⁵, I. El-Battrawy (Bochum)^7
1Universitätsklinikum Mannheim I. Medizinische Klinik Mannheim, Deutschland; ²Universitätsmedizin Göttingen Klinik für Kardiologie und Pneumologie Göttingen, Deutschland; ³Universitätsmedizin Göttingen Herzzentrum Göttingen - Stem Cell Unit Göttingen, Deutschland; ⁴Berufsgenossenschaftlliches Universitätsklinikum Bergmannsheil gGmbH Medizinische Klinik II, Kardiologie und Angiologie Bochum, Deutschland; ⁵Universitätsklinikum Mannheim GmbH I. Medizinische Klinik Mannheim, Deutschland; ⁶Institut für Physiologie, Institut für Forschung und Lehre (IFL), Ruhr-Universität Bochum Abteilung für Zelluläre und Translationale Physiologie, Molekulare und Experimentelle Kardiologie Bochum, Deutschland; ⁷Klinikum der Ruhr-Universität Bochum Medizinische Klinik II, Kardiologie Bochum, Deutschland

Background Brugada syndrome (BrS) is causing sudden cardiac death (SCD) mainly at young age. Studying the underlying mechanisms associated with BrS type I ECG changes in presence of fever and roles of autophagy for BrS remains lacking.

Objectives We sought to study the pathogenic role of a SCN5A gene variant for BrS with fever induced type 1 ECG phenotype. In addition, we studied the role of inflammation and autophagy in the pathomechanism of BrS.

Methods Human induced pluripotent stem cell (hiPSC) lines from a BrS patient harboring a pathogenic variant (c.3148G>A/p. Ala1050Thr) in SCN5A and two healthy donors (non-BrS) and a CRISPR/Cas9 site-corrected cell line (BrS-corr) were differentiated into cardiomyocytes (hiPSC-CMs) for the study.

Results A reduction of Na_v1.5 expression, peak sodium channel current (I_Na) and upstroke velocity (V_max) of action potentials, and an increase in arrhythmic events was detected in BrS compared to non-BrS and BrS-corr cells. Increasing the cell culture temperature from 37°C to 40°C (fever-like-state) exacerbated the phenotypic changes in BrS cells. The fever-effects were enhanced by protein kinase A (PKA) inhibitor but reversed by PKA activator. Lipopolysaccharides (LPS) but not increased temperature up to 40°C enhanced the autophagy level in BrS-hiPSC-CMs by increasing reactive oxidative species (ROS) and inhibiting PI3K/AKT signaling, and hence exacerbated the phenotypic changes. LPS enhanced high temperature related effect on peak I_Na shown in BrS hiPSC-CMs. Effects of LPS and high temperature were not detected in non-BrS cells.

Conclusions The study demonstrated that the SCN5A variant (c.3148G>A/p.Ala1050Thr) caused loss-of-function of sodium channels and increased the channel sensitivity to high temperature and LPS challenge in hiPSC-CMs from a BrS cell line with this variant but not in two non-BrS hiPSC-CM lines. The results suggest that LPS may exacerbate BrS phenotype via enhancing autophagy, whereas fever may exacerbate BrS phenotype via inhibiting PKA-signaling in BrS cardiomyocytes with but probably not limited to this variant.