PKC epsilon is involved in effects of lipopolysaccharide on phenotype of Brugada syndrome with SCN5A variant

Background Fever and inflammation can exacerbate the phenotype of Brugada syndrome (BrS). However, the underlying mechanisms of fever or inflammation in the pathogenesis of BrS are not clarified. This study aimed to study the potential roles of protein kinase C (PKC) in the effects of inflammation on the phenotype of BrS. Method The human induced pluripotent stem cell (hiPSC) lines were generated from fibroblasts of a BrS patient harboring a mutation (c.3148G>A, p.Ala1050Thr) in SCN5A, as well as from a healthy donor and a site-corrected (using CRISPR/Cas9) cell line. Western blot, qPCR, and patch clamp analyses were carried out. Result Lipopolysaccharide (LPS, 2 µg/ml 24 h) reduced peak INa and increased the number of cells displaying arrhythmic events in BrS-hiPSC-CMs but not in healthy donor-hiPSC-CMs, implying that LPS can exacerbate the BrS phenotype. Bisindolylmaleimide I (10 µM), a PKC α/β inhibitor, showed no impact on the LPS effect on peak INa, but Enzastaurin (10 µM), a PKC α/β/ε inhibitor, reversed the LPS effect on INa. Additionally, C2V1 (10 µM), a selective inhibitor of PKC-ε, reversed the LPS effect on INa. A selective PKC-ε activator, RACK (10 µM), could inhibit INa. These data suggest that PKC-ε but not PKC α/β mediated the reduction of INa caused by LPS challenge. Further study showed that LPS increased the expression level of PKC-α in healthy donor-hiPSC-CMs and isogenic cells, but not in BrS-hiPSC-CMs. PKC β/ε expression significantly increased in BrS-hiPSC-CMs. These data may suggest a dissociation between PKC isoform upregulation and sodium channel dysfunction, with PKC ε acting as a dominant effector. Conclusion LPS can exacerbate BrS phenotype through activating PKC-ε. LPS induced a dissociation between PKC isoform upregulation and functional sodium channel regulation.