Abstract 11457: Overexpression of Thioredoxin-1 Ameliorates the Progression of Diabetic Cardiomyopathy by Preservation of Cardiac Function, Increased Survivability and Decreased Fibrosis in Aged Transgenic Mice

Abstract

Introduction: Increased production of reactive oxygen species contributes to the etiology of diabetic complications. It acts as an intracellular antioxidant by scavenging reactive oxygen species (ROS) and protect the cells against oxidative stress and cell death. Hypothesis: To determine the long-term effect of streptozotocin (STZ) induced type 1 diabetes on aging Trx-1 transgenic mice related to survivability, heart function, fibrosis, and apoptosis up to 180 days (d) compared to its corresponding wild-type (WT C57Bl/6J). Method: WT and Trx-1 overexpressed mice (Trx-1 Tg/+ ) (8-12 weeks old) were injected with STZ (i.p. 50mg/kg.body weight(bw)-male; 75mg/kg.bw-female for 5 consecutive days) for induction of diabetes (Dia). Fasting blood sugar level (FBS) was measured 30d after the final injection, and FBS >220mg/dL is used as the cut-off for diabetes. Echocardiography, Survival, FBS measurements were performed on 30, 60, 90, 120, 150, and 180d. Immunohistochemistry was performed on heart tissues (30, 90, and 180d). Results: Dia-Trx-1 Tg/+ mice maintained EF at 60d (61.14±2.3%), 120d (56.1±1.94%) and 180d (60.8±4.3%), when compared to 30d (64.4±1.94%) representing preserved cardiac functions. On the other hand, Dia-WT mice show significant progressive depression of EF at 60d (53.8±1.9%), 120d (48.8±2.1%), and 180d (48.9±1.5%), (p<0.05) when compared to 30d (68.4±6.1%) Dia-WT. Moreover, Dia-Trx-1 Tg/+ mice show significantly higher EF than their corresponding Dia-WT counterparts at each time point measured after diabetic induction (n=8-12, p<0.05). Dia-Trx-1 Tg/+ mice (n=71) also exhibited increased survival rate over Dia-WT (n=47) counterparts with a median survival of 150 days compared to 60 days (Log Rank test: p=0.004). Dia-Trx-1 Tg/+ mice also showed a significant reduction in cardiac fibrosis (4.18±1.08% vs. 17.5±5.1%; p=0.03, n=4) and TUNEL positive cells (3.81±1.49 vs. 7.66±1.46; p=0.03, n=4) when compared to their counterpart (Dia-WT) after 180d of diabetes. Conclusion: These results show that Trx-1 Tg/+ mice preserved cardiac functions, increased survival, decreased apoptosis and fibrosis up to 180d under diabetic conditions, and hence suggesting Trx-1 based treatment strategy could prevent heart failure in aging.