Selective homocysteine-lowering gene transfer attenuates pressure overload-induced cardiomyopathy via reduced oxidative stress

Abstract

Plasma homocysteine levels predict heart failure incidence in prospective epidemiological studies. We evaluated whether selective homocysteine-lowering gene transfer beneficially affects cardiac remodeling and function in a model of pressure overload-induced cardiomyopathy induced by transverse aortic constriction (TAC). Female C57BL/6 low-density lipoprotein receptor (Ldlr (-/-)) cystathionine-β-synthase (Cbs (+/-)) mice were fed standard chow (control mice) or a folate-depleted, methionine-enriched diet to induce hyperhomocysteinemia (diet mice). Three weeks after initiation of thisdiet, mice were intravenously injected with 5 × 10(10) viral particles of an E1E3E4-deleted hepatocyte-specific adenoviral vector expressing Cbs (AdCBS), with the same dose of control vector, or with saline buffer. TAC or sham operation was performed 2 weeks later. AdCBS gene transfer resulted in 86.4 % (p < 0.001) and 84.6 % (p < 0.001) lower homocysteine levels in diet sham mice and diet TAC mice, respectively. Mortality rate was significantly reduced in diet AdCBS TAC mice compared to diet TAC mice during a follow-up period of 8 weeks (hazard ratio for mortality 0.495, 95 % CI 0.249 to 0.985). Left ventricular hypertrophy (p < 0.01) and interstitial myocardial fibrosis (p < 0.001) were strikingly lower in control TAC mice and diet AdCBS TAC mice compared to diet TAC mice. Diastolic function in diet AdCBS TAC mice was similar to that of control TAC mice and was significantly improved compared to diet TACmice. AdCBS gene transfer potently reduced oxidative stress as evidenced by a reduction of plasma TBARS and a reduction of myocardial 3-nitrotyrosine-positive area (%). In conclusion, selective homocysteine lowering potently attenuates pressure overload-induced cardiomyopathy via reduced oxidative stress.

Key message: Plasma homocysteine levels predict heart failure incidence in epidemiological studies. Transverse aortic constriction (TAC) induces pressure overload. Selective homocysteine-lowering gene therapy reduces mortality after TAC. Selective homocysteine lowering attenuates cardiac hypertrophy and fibrosis after TAC. Decreased homocysteine levels enhance diastolic function and lower oxidative stress.