Abstract 2323: Protection of Diabetic Heart with Glutaredoxin Gene Therapy
Glutaredoxin-1 [Grx1], a redox regulator of thioredoxin superfamily has been implicated in myocardial ischemia reperfusion injury. Diabetes is a well-recognized cardiovascular risk factor. Grx1 has been shown to protect the heart from ischemia reperfusion induced injuries. The present study examined whether Grx1 gene therapy could render the diabetic hearts resistant to ischemia reperfusion injury. Diabetes was induced with streptozotocin, and after the diabetes was confirmed, male C57B1/J6 mice were assigned to one of the two groups and open heart surgery was performed. The mice received an intra-myocardial injection of 109 p.f.u. adenovirus encoding Grx1 or injected with empty vector or adenovirus with LacZ. Three days later, the animals were sacrificed and isolated hearts were subjected to 30 min ischemia followed by 2 hours of reperfusion. Ventricular function was examined, and myocardial infarct size and cardiomyocyte apoptosis were determined. Hemodynamic parameters of the Grx1 overexpressed hearts exhibited improved function compared to those treated with either empty vector or LacZ. Grx1 overexpressed hearts also exhibited reduced myocardial infarct size and cardiomyocyte apoptosis. We examined the protein level of ASK1 and the activation of its downstream target JNK, P38MAPK and the level of procaspase 3 as well as the activities of Akt, and c-Src. Grx1 gene therapy inhibited the phosphorylation of c-Src, as well as suppressed the activities of the ASK1 and JNK indicating a reduction of overall death signal. Grx1 overexpression restored the procaspase 3 level. Akt phosphorylation was significantly higher compared to control hearts. The expression of phase II enzyme heme oxygenase-1 was higher after GRX1 gene therapy. Interestingly thioredoxin (Trx)-1 and Trx-2 protein levels were also slightly higher after GRX-1 treatment. The results of this study indicate cardioprotection with Grx1 gene therapy in diabetic hearts as evidenced by improved post ischemic cardiac performance, reduction of myocardial infarct size and cardiomyocite apoptosis as well as significant reduction of ischemia-reperfusion induced death signal.