Abstract
[Background] Tumstatin, a cleaved C-terminal fragment of type IV collagen α3 chain, is known as an endogenous bioactive peptide inducing anti-angiogenic and anti-tumor effects. The expression level of tumstatin was reported to decrease in the cardiac tissue of experimental ischemia-reperfusion (I/R) model pigs. We also clarified that the expression level of tumstatin decreased in the infarcted area of myocardial infarction model rats. I/R injury induces apoptosis of cardiomyocytes through the production of reactive oxygen species (ROS). Recently, we have demonstrated that T3 peptide, an active fragment of tumstatin, inhibited H2O2-induced apoptosis through the suppression of ROS production in rat H9c2 cardiomyoblasts. In the present study, we examined whether T3 peptide inhibits I/R injury through the inhibition of ROS-induced cardiomyocyte death by using in vitro and ex vivo I/R models.
[Methods] In vitro I/R model was created by oxygen and glucose deprivation (OGD) for 12 hours followed by reoxygenation for 1-3 hours (OGD/R) in H9c2 cardiomyoblasts. T3 peptide (30-1000 ng/ml) was treated during the OGD. Cell counting assay was performed to examine a cell viability. The 2', 7'-dichlorodihydrofluorescein diacetate staining was performed to detect intracellular ROS production. To create ex vivo model, the isolated heart of male Wistar rats was perfused by using Langendorff apparatus. Ten minutes after the pre-incubation of T3 peptide (300 ng/ml), the heart was exposed to a global ischemia for 30 min followed by 60 min of reperfusion. Left ventricular (LV) function and electrocardiogram were measured during I/R. The infarcted area was measured by using triphenyltetrazolium chloride staining.
[Results] T3 peptide significantly inhibited OGD/R-induced cell death and intracellular ROS production in H9c2 cardiomyoblasts.T3 peptide significantly decreased the infarcted area induced by I/R injury in the isolated rat heart. Consistently, T3 peptide tended to reverse I/R-induced LV dysfunction and changes in electrocardiogram.
[Conclusions] In this study, we demonstrated for the first time that T3 peptide inhibited I/R injury in cardiomyocytes. These results suggest that T3 peptide can be a novel therapeutic target for ischemic heart diseases.
