Abstract
This study tested the hypothesis that SS31 therapy could effectively protect the heart against transverse aortic constriction (TAC)-induced hypertrophic cardiomyopathy (HCM) damage. Adult-male B6 mice (n=36) were equally divided into sham-operated control (group 1), TAC only (group 2) and TAC+SS31 (group) (2.0 mg/kg/day by intra-peritoneal administration from day 28 after TAC induction) and euthanized by day 60. In vitro results showed that SS31 markedly suppressed angiotensin-II induced protein expressions of BNP/β-MHC, ATM, p-P38 and P53 and ATP damage in H9C2 cells, and protein expression of pro-collagen-I/CTGF in fibroblasts (all P<0.001). By day 60, left ventricular ejection fraction (LVEF) and sarcomere length were significantly lower in group 2 than groups 1 and 3, and significantly lower in group 3 than in group 1, whereas the LEVDd/LVESd and ratio of heart weight to tibial length showed an opposite pattern to LVEF (all P<0.0001). Microscopic findings of numbers of apoptotic nuclei, inflammatory (CD14+, F4/80+) and oxidative-stress (H2DCFDA+) biomarkers, disorganized score of endocardium, and fibrotic and collagen-deposition areas showed an opposite pattern to LVEF among the three groups (all P<0.0001). The protein expressions of inflammatory (PDGF/TNF-α/NF-κB/COX-2), oxidative-stress (NOX-1/NOX-2/oxidized protein), fibrotic (TGF-β/Smad3) apoptotic (cleaved-caspase-3/cleaved-PARP), pressure/volume overload (BNP/β-MHC), CTGF, mitochondrial-damaged (cytosolic cytochrome-C), p-ERK1/2, p-Akt and PI3K signaling showed an opposite pattern to LVEF among the three groups (all P<0.001). The protein expression of anti-oxidants (HO-1/Nrf2) were significantly progressively increased in groups 1 to 3 (all P<0.001). In conclusion, SS31 therapy effectively protected the heart against TAC-induced damage.