Abstract 3925: A Novel Cationic Protein Reduced Infracted Size and Protected Myocytes From Oxidative Stress Through Modification of Akt Signaling
Background: Eosinophil cationic protein is a ribonuclease protein and thus it has been considered to have cytotoxic activity. Recently, we have found the novel function of recombinant human eosinophil cationic protein (rECP) demonstrating the increase of beating rate of cultured neonatal rat cardiomyocytes in a well-harmonized manner. Furthermore, rECP accelerated a differentiation of stem cell to cardiac cells and rECP induced atrial natriuretic factor (ANP) expression in H9c2 cells. The aim of this study was to examine the impact of rECP to protect myocytes under pathological conditions.
Method: Myocardial infarction model was prepared in rats and rECP or saline (PS) was injected. After 7 days, cardiac function was measured by echocardiography and heart was embedded in paraffin. The sections were stained with hematoxylin and eosin or Masson Trichrome and the effect of rECP on the ventricular remodeling after MI was investigated. Next, we examined the role of rECP in cell survival against H2O2 (200 μM)-induced apoptosis in H9c2 cells. Reactive oxygen species (ROS) were detected using chloromethyl-20,70-dichlorodihydrofluorescein diacetate (DCFH-DA) assay. Apoptosis was evaluated by Caspase-3 assay and TUNEL staining and cell viability was measured by MTS assay. Expression of Akt, pAkt, Bcl-2, ERK1/2, pERK1/2 was evaluated by Western blot analysis.
Result: Echocardiography demonstrated a preserved cardiac function after MI in ECP-treated rats compare with PS-treated rats (FS: 37.6±14.8% for rECP vs 12.5±7.0% for PS (p<0.01) and LVDd: 7.2±0.9mm for rECP vs 8.4±0.7mm for PS (p<0.01), respectively). rECP attenuated ventricular remodeling index after MI compared with control rats (1.03±0.10 for rECP and 2.94±0.37 for PS, p<0.05). In vitro, rECP significantly reduced ROS production and apoptosis was reduced in Caspase-3 (11.7% decrease by rECP), TUNEL staining (8.0% decrease by rECP). Cell viability was significantly improved by rECP (117% increase). PI3K/Akt pathways was significantly activated by rECP.
Conclusion: Our results indicate rECP has protecting effects on hearts in pathological condition such as myocardial infarction and oxidative stress and the mechanism of its action involves the modulation of PI3K/Akt pathways.