Role of Soluble ST2 as a Marker for Rejection after Heart Transplant

BACKGROUND AND OBJECTIVES: Endomyocardial biopsy is obligatory during the first year after heart transplant (HTx) for the surveillance of acute rejection. Previous attempts using cardiac biomarkers for the detection of rejection failed to show enough evidence to substitute endomyocardial biopsy. Therefore, this study sought the possibility of using soluble ST2 (sST2), a novel cardiovascular marker, as a surrogate marker for acute allograft rejection after HTx. SUBJECTS AND METHODS: A total of 494 blood samples acquired at the time of endomyocardial biopsy were analyzed in 67 HTx cases from September 2006 to August 2014. Significant rejection was defined as International Society of Heart and Lung Transplant (ISHLT) score ≥2R and humoral rejection accompanied by hemodynamic instability. RESULTS: Twenty cases of HTx with 22 blood samples showed significant rejection in endomyocardial biopsy at 4.0 (2.0-9.0) months after HTx. The level of sST2 showed positive correlation with cardiac troponin I, and N-terminal pro-B-type natriuretic peptide (all p<0.001), and negative correlation with post-HTx months (p<0.001). The levels of sST2 according to the ISHLT scores were 36 (19-98), 28 (18-62), 15 (16-37), and 191 (85-343) ng/mL, consecutively 0R, 1R, 2R, and 3R+ (3R plus hemodynamically-unstable humoral rejection) (p=0.003). However, when we studied within-subject effects of sST2 using a mixed model, the sST2 level according to the predefined time point was not different according to the presence of significant rejection (p for interaction=0.94). CONCLUSION: Although sST2 is known as a promising predictor for cardiovascular events, its role in HTx patients to predict acute allograft rejection seems to be limited.

Effects of Cardiotrophin-1 on Adriamycin-Induced Apoptosis in H9c2 Cardiomyoblasts

BACKGROUND AND OBJECTIVES: Adriamycin (doxorubicin, ADR) is a highly effective anti-neoplastic drug, but its clinical use is limited by its adverse side effects on the heart. Cardiotrophin (CT-1), a potent cardiac survival factor, is capable of inhibiting apoptosis in cardiac myocytes. The aim of this study was to investigate the cyto-protective effects of CT-1 against ADR-induced apoptosis in vitro. MATERIALS AND METHODS: We determined a reasonable ADR concentration for inducing cell death by utilizing a cell survival test performed in a dose-dependent manner. To determine the requirements for apoptosis in ADR-treated cardiac myocytes (H9c2 cells), we examined the effect of CT-1 on survival and apoptotic changes using a cell counting kit (CCK), RT-PCR, and Western blotting. RESULTS: In analyzing cell survival as determined by CCK, ADR-induced cell death was found to occur in a dose-dependent manner (50% death at 24 hours after 2 micrometer of ADR), and ADR was shown to decrease procaspase-3. On RT-PCR, expression of Bax-alpha mRNA increased and Bcl-2 decreased during the 24 hours after ADR treatment. Consequently, the ratio of Bax-alpha/Bcl-2 mRNA peaked at 24 hours after ADR treatment. In contrast, CT-1 effectively attenuated the ADR-induced cell death in a dose-dependent manner. The changes in Bax-alpha and Bcl-2 mRNA expression after ADR treatment were reversed by CT-1 (1 ng/mL) treatment. The protein levels of procaspase-3 decreased after ADR treatment, an effect which was reversed by CT-1 treatment. Akt phosphorylation was also increased by CT-1, demonstrating that CT-1 inhibited apoptosis induced by ADR. CONCLUSION: These data demonstrated that ADR-induced apoptosis of cardiomyocytes can be prevented by CT-1; therefore, it may be possible to use CT-1 as a cardioprotective agent during ADR chemotherapy in patients with cancer.