Abstract 10973: Tenascin-C Deficiency Rescues the Effect of Diabetes on Cardiac and Vascular Dysfunction in Mice

Abstract

Introduction: Tenascin-C (TN-C) upregulation is linked to worse clinical outcome in diabetic patients. However, the role of TN-C in the development of diabetic cardiomyopathy is still unknown. Hypothesis: Whether TN-C plays a maladaptive role in diabetic cardiomyopathy. Methods: AJ (n=14) and TNC-KO (n=16) adult male mice were injected with streptozotocin (50mg/kg) to induce diabetes. Cardiac function was measured by echocardiography at 16-18 weeks follow-up. Additionally, cardiomyocyte passive stiffness , vascular endothelial function (aorta), and cardiac fibrosis were assessed. In addition, the hemodynamic effect of human recombinant TN-C (hrTN-C; 80 ng/ml) on the isolated working rat heart (n=3) was evaluated. Isolated primary mouse cardiomyocytes (IPMC) were used to assess TN-C expression. Human ventricular cardiac fibroblasts (HCF) were cultured and treated with 1) TGF-β (20ng/ml); 2) rhTN-C (10μg/ml) and TLR4 inhibitor (TAK-242, 50 mM) in combination with TN-C and mRNA expression of α-SMA, TN-C, Col-1, Col-3 and ACE1 were assessed by RT-qPCR. Finally, HUVEC were treated either with rhTN-C (10μg/ml) or combination with TLR-4 inhibitor and analysed of the expression of NADPH oxidase 1 and 4 (NOX1, NOX4). Results: TN-C deficiency was accompanied by preserved LV ejection fraction and endothelium function in aorta (p<0.05, respectively). Diabetic TN-C KO mice show reduction in cardiomyocyte stiffness and diastolic dysfunction as compared to AJ diabetic group (p<0.01). Histology revealed less cardiac and perivascular fibrosis in diabetic TN-C KO animals than in the AJ diabetic group (p<0.01). In addition, rhTN-C resulted in reduction in cardiac function in isolated rat hearts. mRNA expression of TN-C was increased in IPMC. Moreover, TGF-β treatment markedly upregulated TN-C expression (p<0.01) and rhTN-C promoted pro-fibrotic genes expression (p<0.05, respectively). HUVEC incubated with rhTN-C showed increased expression of IL-6 and NOX4 via TLR-4 signalling. Conclusions: TN-C promotes a hostile environment that facilitates fibrosis and oxidative stress leading to cardiomyocyte and endothelial cell dysfunction. Thus, TN-C may play a crucial role in cardiovascular dysfunction in diabetes as well as a potential target for therapy.