Project description:Rationale. Sickle cell cardiomyopathy is characterized by prolonged QTc, myocardial fibrosis, diastolic dysfunction, and vulnerability to ventricular tachycardia (VT). Based on previous reports, IL-18 mediates cardiac fibrosis and its promoter SNPs are associated with sudden cardiac death in a non-sickle population. We, therefore, hypothesized that IL-18 may mediate cardiomyopathy and VT in sickle cell disease. Findings. Sickle cell patients with evidence of myocardial fibrosis demonstrated greater IL18 expression. Patients with higher IL18 gene expression levels also exhibited increased QTc intervals and overall mortality. A novel SNP within IL-18, rs5744285, was associated with both QTc and IL-18 expression levels. Similar to sickle cell patients, sickle mice demonstrated increased cardiac fibrosis and prolonged action potential duration (APD) associated with higher VT inducibility. Administration of exogenous IL-18 acutely ex vivo to hearts resulted in increased triggered activity and VTs while inhibition of IL-18 resulted in reduced cardiac NFkB expression, fibrosis, and dysfunction in sickle mice. Conclusions. IL-18 is associated with prolonged QTc, myocardial fibrosis, and mortality in sickle cell patients, and prolonged APD associated with heightened VT susceptibility in sickle mice. Inhibition of IL-18 improves cardiac function, in part, via NFκB. Inflammatory cytokines contribute to the development of sickle cardiomyopathy and inducible VT.
Project description:Hypertrophic cardiomyopathy (HCM) caused by autosomal-dominant mutations in genes that code for the structural proteins of the sarcomere, is the most common inherited heart disease. HCM is associated with progressive myocardial hypertrophy and fibrosis, ventricular dysfunction, and arrhythmias. Disease onset during childhood and adolescence carries the risk of morbidity and sudden cardiac death. Hypoxia and the main regulator of the cellular hypoxic response hypoxia-inducible transcription factor-1a (HIF1A) have been associated with HCM, however their exact roles are not elucidated yet.
Project description:Mutations in RBM20, a splicing factor that targets multiple pivotal cardiac genes including TTN and CAMK2D, cause a clinically aggressive form of dilated cardiomyopathy (DCM) with a high risk of malignant ventricular arrhythmias. We hypothesized that the RBM20 target CAMK2D contributes critically to RBM20 cardiomyopathy. Here, we sequenced the hearts of Rbm20/Camk2d double knockout mice, as well as the hearts of Rbm20-R636Q knock-in mice treated with the CAMK2 inhibitor Hesperadin.
