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 (cTnI-G203S) 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 cTnI-G203S 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. cTnI-G203S or age-matched wt 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 cTnI-G203S hearts consistent with increased anaplerosis. We also reveal that AID-TAT treatment of precardiomyopathic cTnI-G203S 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.

Preventative therapeutic approaches for hypertrophic cardiomyopathy

“…Recent studies have investigated the use of AID‐TAT peptide as a potential HCM therapeutic (Viola et al . 2020 ). Unlike β‐blockers and Ca 2+ channel blockers, AID‐TAT peptide specifically targets the AID region of the cardiac I Ca‐L , immobilizing movement of the I Ca‐L β 2 subunit (Fig.…”

“… 2000 ; Viola et al . 2020 ). Twenty‐week‐old pre‐cardiomyopathic cTnI‐G203S mice were treated with AID‐TAT peptide (10 µ m ) three times a week for 5 weeks (Viola et al .…”

“…Treatment of 30‐week‐old post‐cardiomyopathic cTnI‐G203S mice with established hypertrophy with AID‐TAT peptide did not significantly improve mitochondrial metabolic activity, cell size, heart weight to body weight ratio (HW:BW) or echocardiographic parameters (Viola et al . 2020 ). These studies indicate that early therapeutic intervention with AID‐TAT peptide may represent a viable approach to restore structural–functional communication between I Ca‐L and mitochondria, normalize metabolic activity and prevent the development of HCM.…”

“…Studies utilizing transgenic mouse models of HCM indicate that a structural-functional 'breakdown' between the cardiac I Ca-L and mitochondria via sarcomeric proteins may lead to the development of a hypermetabolic mitochondrial state, which precedes development of HCM pathology (Viola et al 2016a,b). Recent studies have investigated the use of AID-TAT peptide as a potential HCM therapeutic (Viola et al 2020). Unlike β-blockers and Ca 2+ channel blockers, AID-TAT peptide specifically targets the AID region of the cardiac I Ca-L , immobilizing movement of the I Ca-L β 2 subunit (Fig.…”

“…Unlike β-blockers and Ca 2+ channel blockers, AID-TAT peptide specifically targets the AID region of the cardiac I Ca-L , immobilizing movement of the I Ca-L β 2 subunit (Fig. 1) (Hohaus et al 2000;Viola et al 2020). Twenty-week-old pre-cardiomyopathic cTnI-G203S mice were treated with AID-TAT peptide (10 µM) three times a week for 5 weeks (Viola et al 2020).…”