Identification of potential biomarkers for predicting the early onset of diabetic cardiomyopathy in a mouse model.

Type 2 diabetes (T2D) is characterized by metabolic derangements that cause a shift in substrate preference, inducing cardiac interstitial fibrosis. Interstitial fibrosis plays a key role in aggravating left ventricular diastolic dysfunction (LVDD), which has previously been associated with the asymptomatic onset of heart failure. The latter is responsible for 80% of deaths among diabetic patients and has been termed diabetic cardiomyopathy (DCM). Through in silico prediction and subsequent detection in a leptin receptor-deficient db/db mice model (db/db), we confirmed the presence of previously identified potential biomarkers to detect the early onset of DCM. Differential expression of Lysyl Oxidase Like 2 (LOXL2) and Electron Transfer Flavoprotein Beta Subunit (ETFß), in both serum and heart tissue of 6-16-week-old db/db mice, correlated with a reduced left-ventricular diastolic dysfunction as assessed by high-resolution Doppler echocardiography. Principal component analysis of the combined biomarkers, LOXL2 and ETFß, further displayed a significant difference between wild type and db/db mice from as early as 9 weeks of age. Knockdown in H9c2 cells, utilising siRNA of either LOXL2 or ETFß, revealed a decrease in the expression of Collagen Type I Alpha1 (COL1A1), a marker known to contribute to enhanced myocardial fibrosis. Additionally, receiver-operating curve (ROC) analysis of the proposed diagnostic profile showed that the combination of LOXL2 and ETFß resulted in an area under the curve (AUC) of 0.813, with a cut-off point of 0.824, thus suggesting the favorable positive predictive power of the model and further supporting the use of LOXL2 and ETFß as possible early predictive DCM biomarkers.

Aspalathin ameliorates doxorubicin-induced oxidative stress in H9c2 cardiomyoblasts.

Aspalathin (ASP) is a C-dihydrochalcone abundantly found in Aspalathus linearis. While we have provide evidence that ASP can protect H9c2 cardiomyoblasts against doxorubicin (Dox)-induced apoptosis through regulation of autophagy, the complete mechanism involved in the cardioprotective effect of this dihydrochalcone remains to be explored. Here we provide evidence that ASP reverses Dox-induced apoptosis through the amelioration of oxidative stress in H9c2 cardiomyoblasts. Cultured cells were treated with 0.2 µM Dox or co-treated with either 20 µM dexrazoxane (Dexra) or 0.2 µM ASP daily for five days, to a final dose of 1 µM Dox, 100 µM Dexra and 1 µM ASP, respectively. Superoxide dismutase, catalase, glutathione, malondialdehyde and dichloro-dihydro-fluorescein diacetate fluorescence were used as end-point measurements for oxidative stress, while JC-1 and TUNEL labeling were performed to assess mitochondria depolarization and apoptosis. Co-treatment with ASP attenuated Dox-induced cardiotoxicity by improving endogenous antioxidant levels and mitochondrial membrane potential, while inhibiting reactive oxygen species production and cellular apoptosis. These findings suggested that ASP can prevent Dox-induced oxidative stress and apoptosis and needs further assessment to confirm its therapeutic potential to prevent Dox-induced cardiotoxicity.