Lipopolysaccharide Modifies Sodium Current Kinetics through ROS and PKC Signalling in Induced Pluripotent Stem-Derived Cardiomyocytes from Brugada Syndrome Patient

Abstract

Studies have suggested a connection between inflammation and arrhythmogenesis of Brugada syndrome (BrS). However, experimental studies regarding the roles of inflammation in the arrhythmogenesis of BrS and its underlying mechanism are still lacking. This study aimed to investigate the influence of inflammation on BrS-phenotype features using human-induced stem cell-derived cardiomyocytes (hiPSC-CMs) from a BrS-patient carrying an SCN10A variant (c.3749G > A). After LPS treatment, the peak sodium current decreased significantly in SCN10A-hiPSC-CMs, but not in healthy donor-hiPSC-CMs. LPS also changed sodium channel gating kinetics, including activation, inactivation, and recovery from inactivation. NAC (N-acetyl-l-cysteine), a blocker of ROS (reactive oxygen species), failed to affect the sodium current, but prevented the LPS-induced reduction of sodium channel currents and changes in gating kinetics, suggesting a contribution of ROS to the LPS effects. Hydrogen peroxide (H2O2), a main form of ROS in cells, mimicked the LPS effects on sodium channel currents and gating kinetics, implying that ROS might mediate LPS-effects on sodium channels. The effects of H2O2 could be attenuated by a PKC blocker chelerythrine, indicating that PKC is a downstream factor of ROS. This study demonstrated that LPS can exacerbate the loss-of-function of sodium channels in BrS cells. Inflammation may play an important role in the pathogenesis of BrS.

Septic Cardiomyopathy: From Pathophysiology to the Clinical Setting

“…Detrimental effects of endotoxemia on cardiac contractility are largely due to mitochondrial dysfunction that leads to abnormal calcium handling, disruption of ATP synthesis, endothelium reticulum stress, and autophagy. Furthermore, LPS leads to electrophysiological dysfunctions through a both a direct and cytokine-mediated effect on sodium current kinetics and non-selective cation channel transient receptor potential vanilloid 1 (TRPV1) [ 34 , 35 , 36 , 37 ]. Furthermore, LPS and its downstream mediator TNF-α, IL-1β, IL-6, and C5a and ROS [ 38 , 39 ] critically alter calcium (Ca ++ ) homeostasis by blunting the amplitude of intracellular currents and concentrations.…”

Automated Patch-Clamp and Induced Pluripotent Stem Cell-Derived Cardiomyocytes: A Synergistic Approach in the Study of Brugada Syndrome

“…These include long-term culture, culture on a rigid substrate [ 65 , 66 ], electrical and mechanical stimulation [ 67 , 68 ], and the use of biochemical cues such as the growth hormone Tri-iodo-L-thyronine [ 69 ]. These advancements refined the iPS-CM technique and have allowed the production and characterisation of iPSCs leading to a deeper understanding of different ion channels involved in BrS, including L-type Ca 2+ channels [ 70 , 71 ], the tetrodotoxin (TTX)-resistant Na + voltage-gated channel alpha subunit 10 ( SCN10A ) [ 72 , 73 ], and K + channels including the K + voltage-gated channel subfamily Q member 1 ( KCNQ1 ) and the K + voltage-gated channel subfamily H member 2 ( KCNH2 ) [ 3 , 74 ].…”

“…The data showed that after 48 h of incubation, the patient-derived cells displayed a decrease in the already impaired Na + peak current density and small but significant changes in channel kinetics compared to control cells derived from three healthy donors. Additionally, the effect was prevented by the protein kinase C (PKC) inhibitor chelerythrine, indicating that inflammation may worsen LoF Na + variants in BrS patients through enhanced reactive oxygen species (ROS)-PKC signalling [ 73 ]. In a separate study, Belbachir and colleagues identified a variant in the Ras associated with diabetes (RAD) guanosine triphosphatases (GTPase) gene ( RRAD ) in a BrS patient, derived iPSC-CMs and found a reduction in the velocity of the AP upstroke, prolonged AP duration, and increased probability of early afterdepolarisations (EADs), as well as a reduction in Na + and Ca 2+ peak current densities and increased late I Na .…”