[HTML][HTML] Impaired branched chain amino acid oxidation contributes to cardiac insulin resistance in heart failure
Cardiovascular diabetology, 2019•Springer
Background Branched chain amino acids (BCAA) can impair insulin signaling, and cardiac
insulin resistance can occur in the failing heart. We, therefore, determined if cardiac BCAA
accumulation occurs in patients with dilated cardiomyopathy (DCM), due to an impaired
catabolism of BCAA, and if stimulating cardiac BCAA oxidation can improve cardiac function
in mice with heart failure. Method For human cohorts of DCM and control, both male and
female patients of ages between 22 and 66 years were recruited with informed consent from …
insulin resistance can occur in the failing heart. We, therefore, determined if cardiac BCAA
accumulation occurs in patients with dilated cardiomyopathy (DCM), due to an impaired
catabolism of BCAA, and if stimulating cardiac BCAA oxidation can improve cardiac function
in mice with heart failure. Method For human cohorts of DCM and control, both male and
female patients of ages between 22 and 66 years were recruited with informed consent from …
Background
Branched chain amino acids (BCAA) can impair insulin signaling, and cardiac insulin resistance can occur in the failing heart. We, therefore, determined if cardiac BCAA accumulation occurs in patients with dilated cardiomyopathy (DCM), due to an impaired catabolism of BCAA, and if stimulating cardiac BCAA oxidation can improve cardiac function in mice with heart failure.
Method
For human cohorts of DCM and control, both male and female patients of ages between 22 and 66 years were recruited with informed consent from University of Alberta hospital. Left ventricular biopsies were obtained at the time of transplantation. Control biopsies were obtained from non-transplanted donor hearts without heart disease history. To determine if stimulating BCAA catabolism could lessen the severity of heart failure, C57BL/6J mice subjected to a transverse aortic constriction (TAC) were treated between 1 to 4-week post-surgery with either vehicle or a stimulator of BCAA oxidation (BT2, 40 mg/kg/day).
Result
Echocardiographic data showed a reduction in ejection fraction (54.3 ± 2.3 to 22.3 ± 2.2%) and an enhanced formation of cardiac fibrosis in DCM patients when compared to the control patients. Cardiac BCAA levels were dramatically elevated in left ventricular samples of patients with DCM. Hearts from DCM patients showed a blunted insulin signalling pathway, as indicated by an increase in P-IRS1ser636/639 and its upstream modulator P-p70S6K, but a decrease in its downstream modulators P-AKT ser473 and in P-GSK3β ser9. Cardiac BCAA oxidation in isolated working hearts was significantly enhanced by BT2, compared to vehicle, following either acute or chronic treatment. Treatment of TAC mice with BT2 significantly improved cardiac function in both sham and TAC mice (63.0 ± 1.8 and 56.9 ± 3.8% ejection fraction respectively). Furthermore, P-BCKDH and BCKDK expression was significantly decreased in the BT2 treated groups.
Conclusion
We conclude that impaired cardiac BCAA catabolism and insulin signaling occur in human heart failure, while enhancing BCAA oxidation can improve cardiac function in the failing mouse heart.
Springer