Characterization and validation of a preventative therapy for hypertrophic cardiomyopathy in a murine model of the disease.

Abstract

Currently there is an unmet need for treatments that can prevent hypertrophic cardiomyopathy (HCM). Using a murine model we previously identified that HCM causing cardiac troponin I mutation Gly203Ser (<i>cTnI-G203S</i>) is associated with increased mitochondrial metabolic activity, consistent with the human condition. These alterations precede development of the cardiomyopathy. Here we examine the efficacy of in vivo treatment of <i>cTnI-G203S</i> mice with a peptide derived against the α-interaction domain of the cardiac L-type calcium channel (AID-TAT) on restoring mitochondrial metabolic activity, and preventing HCM. <i>cTnI-G203S</i> or age-matched <i>wt</i> mice were treated with active or inactive AID-TAT. Following treatment, targeted metabolomics was utilized to evaluate myocardial substrate metabolism. Cardiac myocyte mitochondrial metabolic activity was assessed as alterations in mitochondrial membrane potential and flavoprotein oxidation. Cardiac morphology and function were examined using echocardiography. Cardiac uptake was assessed using an in vivo multispectral imaging system. We identified alterations in six biochemical intermediates in <i>cTnI-G203S</i> hearts consistent with increased anaplerosis. We also reveal that AID-TAT treatment of precardiomyopathic <i>cTnI-G203S</i> mice, but not mice with established cardiomyopathy, restored cardiac myocyte mitochondrial membrane potential and flavoprotein oxidation, and prevented myocardial hypertrophy. Importantly, AID-TAT was rapidly targeted to the heart, and not retained by the liver or kidneys. Overall, we identify biomarkers of HCM resulting from the cTnI mutation Gly203Ser, and present a safe, preventative therapy for associated cardiomyopathy. Utilizing AID-TAT to modulate cardiac metabolic activity may be beneficial in preventing HCM in "at risk" patients with identified Gly203Ser gene mutations.