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PLoS One. 2018 Dec 6;13(12):e0208321. doi: 10.1371/journal.pone.0208321. eCollection 2018.

Interleukin-6 inhibition of hERG underlies risk for acquired long QT in cardiac and systemic inflammation.

Author information

1
Cardiovascular Research Program, VA New York Harbor Healthcare System, Brooklyn, New York, United States of America.
2
Department of Cell Biology and Pharmacology, State University of New York Downstate Medical Center, Brooklyn, New York, United States of America.
3
Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy.
4
Centre de Recherche, Institut Universitaire en Santé Mentale de Québec, Department of Medicine, Université Laval, Quebec City, Quebec, Canada.
5
Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Siena, Italy.
6
Departments of Medicine, State University of New York Downstate Medical Center, Brooklyn, New York, United States of America.
7
Department of Medicine, New York University School of Medicine, New York, United States of America.

Abstract

Increased proinflammatory interleukin-6 (IL-6) levels are associated with acquired long QT-syndrome (LQTS) in patients with systemic inflammation, leading to higher risks for life-threatening polymorphic ventricular tachycardia such as Torsades de Pointes. However, the functional and molecular mechanisms of this association are not known. In most cases of acquired LQTS, the target ion channel is the human ether-á-go-go-related gene (hERG) encoding the rapid component of the delayed rectifier K current, IKr, which plays a critical role in cardiac repolarization. Here, we tested the hypothesis that IL-6 may cause QT prolongation by suppressing IKr. Electrophysiological and biochemical assays were used to assess the impact of IL-6 on the functional expression of IKr in HEK293 cells and adult guinea-pig ventricular myocytes (AGPVM). In HEK293 cells, IL-6 alone or in combination with the soluble IL-6 receptor (IL-6R), produced a significant depression of IKr peak and tail current densities. Block of IL-6R or Janus kinase (JAK) reversed the inhibitory effects of IL-6 on IKr. In AGPVM, IL-6 prolonged action potential duration (APD) which was further prolonged in the presence of IL-6R. Similar to heterologous cells, IL-6 reduced endogenous guinea pig ERG channel mRNA and protein expression. The data are first to demonstrate that IL-6 inhibition of IKr and the resulting prolongation of APD is mediated via IL-6R and JAK pathway activation and forms the basis for the observed clinical QT interval prolongation. These novel findings may guide the development of targeted anti-arrhythmic therapeutic interventions in patients with LQTS and inflammatory disorders.

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