The cardiac glycoside ouabain activates NLRP3 inflammasomes and promotes cardiac inflammation and dysfunction.

Motoi Kobayashi,Fujio Kayama,Nathan Mise,Tadayoshi Karasawa,Masafumi Takahashi,Naoyuki Hasebe,Hiroaki Kimura,Fumitake Usui-Kawanishi,Tadashi Kasahara,Sachiko Watanabe,Hiroyasu Nakano

doi:10.1371/journal.pone.0176676

Motoi Kobayashi, Fujio Kayama + Show 9 more

Open Access

https://doi.org/10.1371/journal.pone.0176676

Copy DOI

Journal: PloS one	Publication Date: May 11, 2017
Citations: 31	License type: CC BY 4.0

Affiliation: Jichi Medical University, Asahikawa Medical University

Abstract

Cardiac glycosides such as digoxin are Na+/K+-ATPase inhibitors that are widely used for the treatment of chronic heart failure and cardiac arrhythmias; however, recent epidemiological studies have suggested a relationship between digoxin treatment and increased mortality. We previously showed that nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasomes, which regulate caspase-1-dependent interleukin (IL)-1β release, mediate the sterile cardiovascular inflammation. Because the Na+/K+–ATPase is involved in inflammatory responses, we investigated the role of NLRP3 inflammasomes in the pathophysiology of cardiac glycoside-induced cardiac inflammation and dysfunction. The cardiac glycoside ouabain induced cardiac dysfunction and injury in wild-type mice primed with a low dose of lipopolysaccharide (LPS), although no cardiac dysfunction was observed in mice treated with either ouabain or LPS alone. Ouabain also induced cardiac inflammatory responses, such as macrophage infiltration and IL-1β release, when mice were primed with LPS. These cardiac manifestations were all significantly attenuated in mice deficient in IL-1β. Furthermore, deficiency of NLRP3 inflammasome components, NLRP3 and caspase-1, also attenuated ouabain-induced cardiac dysfunction and inflammation. In vitro experiments revealed that ouabain induced NLRP3 inflammasome activation as well as subsequent IL-1β release from macrophages, and this activation was mediated by K+ efflux. Our findings demonstrate that cardiac glycosides promote cardiac inflammation and dysfunction through NLRP3 inflammasomes and provide new insights into the mechanisms underlying the adverse effects of cardiac glycosides.

Highlights

The major findings of this study are as follows: (1) ouabain induces cardiac dysfunction and injury in WT mice primed with a low dose of LPS; (2) ouabain induces cardiac inflammatory responses, such as macrophage infiltration and IL-1β release; (3) the aforementioned cardiac manifestations are all significantly attenuated in mice deficient in NLRP3 inflammasomerelated molecules, such as NLRP3, Casp1, and IL-1β; (4) ouabain induces NLRP3 inflammasome activation and subsequent IL-1β release in macrophages primed with a low dose of LPS; NLRP3 inflammasomes in ouabain-induced cardiac dysfunction and (5) ouabain-induced activation of NLRP3 inflammasomes is mediated through K+ efflux
The results of the present study demonstrate that the Na+/K+-ATPase inhibitor ouabain induces NLRP3 inflammasome activation through K+ efflux, leading to cardiac inflammation and dysfunction
Because recent epidemiologic studies have suggested that digoxin therapy is associated with an increased risk of mortality, in patients with atrial fibrillation (AF) [3, 4], our findings demonstrate a novel action of cardiac glycosides and provide new insights into the causal link between the use of cardiac glycosides and their potential adverse effects

Summary

Introduction

CREST) (MT:16gm0610012h0103), and the Salt Science Research Foundation (MT:No.1541). Competing interests: The authors have declared that no competing interests exist. Recent investigations have suggested that in addition to its iron-pumping function, the Na+/K+-ATPase serves as a scaffold protein that interacts with neighboring proteins and potentiates multiple signaling pathways, leading to the activation of transcriptional factors, such as nuclear factor (NF)-κB and activator protein-1. These effects suggest that the Na+/K+-ATPase modulates inflammatory responses [5,6,7], but a causal link between the Na+/K+-ATPase and inflammation is not fully understood. Because the Na+/K+-ATPase modulates intracellular K+ concentrations [1, 6], we hypothesize that cardiac glycosides could influence NLRP3 inflammasome activation and subsequent IL-1β release in the heart. The findings of this study demonstrate a novel role of NLRP3 inflammasomes in the heart and provide new insights into the mechanisms underlying the adverse effects of cardiac glycosides

Materials and methods

Results

Discussion