Ruijun Li

Salubrinal protects against tunicamycin and hypoxia induced cardiomyocyte apoptosis via the PERK-eIF2α signaling pathway.

Objectives This study examined the protective effect of salubrinal and the mechanism underlying this protection against tunicamycin (TM)- and hypoxia-induced apoptosis in rat cardiomyocytes. Methods Neonatal rat cardiomyocytes were cultured from the ventricles of 1-day-old Wistar rats. Cells were exposed to different concentrations of salubrinal (10, 20, and 40 µmol/L) for 30 min followed by TM treatment or hypoxia for 36 h. Apoptosis was measured by a multiparameter HCS (high content screening) apoptosis assay, TUNEL assay and flow cytometry. The phosphorylation of eukaryotic translation initiation factor 2 subunit alpha (eIF2α) and the expression of cleaved caspase-12 were determined by Western blotting. C/EBP homologous protein (CHOP) was detected by immunocytochemistry. Results HCS, TUNEL assays and flow cytometry showed that salubrinal protected cardiomyocytes against apoptosis induced by TM or hypoxia. Western blotting showed that salubrinal protected cardiomyocytes against apoptosis by inducing eIF2α phosphorylation and down-regulating the expression of the endoplasmic reticulum stress-mediated apoptotic proteins, CHOP and cleaved caspase-12. Conclusions Our study suggests that salubrinal protects rat cardiomyocytes against TM- or hypoxia-associated apoptosis via a mechanism involving the inhibition of ER stress-mediated apoptosis.

Inhibition of serine/threonine protein phosphatase PP1 protects cardiomyocytes from tunicamycin-induced apoptosis and I/R through the upregulation of p-eIF2α.

The serine/threonine protein phosphatase PP1 mediates the dephosphorylation of phosphorylated eukaryotic translation initiation factor 2 subunit α (p-eIF2α), which is a central regulator of protein synthesis. In the present study, we examined the protective effects of PP1–12 (an inhibitor of the serine/threonine protein phosphatase PP1) against tunicamycin (TM)-induced apoptosis in cultured cardiomyocytes in vitro, as well as in an in vivo model of ischemia/reperfusion (I/R) injury in rat hearts. Neonatal cardiomyocytes cultured from the ventricles of the hearts of 1-day-old Wistar rats were exposed to various concentrations of PP1–12 (0.3, 1 and 3 μmol/l) for 30 min, followed by treatment with TM for 36 h. Cell viability was assessed by adenosine triphosphate (ATP) bioluminescence, and the results revealed that pre-treatment with PP1–12 protected cell viability. Western blot analysis revealed that PP1–12 induced eIF2α phosphorylation and immuncytochemistry indicated that PP1–12 downregulated the expression of C/EBP homologous protein (CHOP), which is related to apoptosis. PP1–12 suppressed cell apoptosis, with maximum protective effects displayed at the concentration of 3 μmol/l. For the in vivo experiments, male Sprague-Dawley rats were randomly divided into 5 groups: i) sham-operated; ii) vehicle (I/R + DMSO); iii) I/R + 1 mg/kg/day PP1–12; iv) I/R + 3 mg/kg/day PP1–12; and v) I/R + 10 mg/kg/day PP1–12. PP1–12 reduced the expression of cleaved caspase-12 and increased the phosphorylation of eIF2α, as revealed by western blot analysis. By calculating the apoptotic index (AI), we found that 10 mg/kg/day PP1–12 exerted the most pronounced anti-apoptotic effect. The infarction area was significantly decreased following treatment with this concentration of PP1–12, as revealed by 2,3,5-triphenyltetrazolium chloride (TTC) staining. Taken together, these data suggest that PP1–12 protects cardiomyocytes from TM- and I/R-induced apoptosis, and this effect is achieved at least in part through the inhibition of cell apoptosis and the induction of eIF2α phosphorylation.

Usefulness of the Neutrophil-to-Lymphocyte Ratio in Predicting Adverse Events in Elderly Patients With Chronic Heart Failure

The neutrophil-to-lymphocyte (N/L) ratio has been associated with poor outcomes in patients with cardiovascular diseases, but it has not been studied in elderly patients with chronic heart failure (CHF).In this study, we analyzed 1355 elderly patients admitted with CHF. A multivariate logistic regression model was used to assess the independent association of the N/L ratio with chronic kidney disease (CKD). The patients were then divided into tertiles according to the N/L ratios. We used Cox regression analysis to assess the association between the N/L ratio and subsequent major cardiovascular events (MCE), including cardiac death and rehospitalization for heart failure.In the multiple logistic regression analysis, the N/L ratio was identified as a risk factor for CKD in elderly patients with CHF (odds ratio [OR] = 1.170, 95% confidence interval [CI] 1.054 to 1.298, P = 0.003). The median follow-up period was 18 months. In a multivariate analysis with the lowest tertile as the reference, the highest tertile of the N/L ratio remained significantly associated with MCE (hazard ratio [HR] = 1.425, 95% CI 1.109 to 1.832, P = 0.006), cardiac death (HR = 1.747, 95% CI 1.032 to 2.958, P = 0.038), and rehospitalization for heart failure (HR = 1.461, 95% CI 1.108 to 1.927, P = 0.007).In elderly patients with CHF, the N/L ratio is one of the important risk factors for CKD and the highest tertile of the N/L ratio is associated with an increased risk for MCE.

Usefulness of S100A12 as a prognostic biomarker for adverse events in patients with heart failure.

OBJECTIVES S100A12 has been proposed as a novel pivotal factor in inflammation produced by granulocytes. The purpose of this study was to investigate the relationship between S100A12 and chronic heart failure (CHF). DESIGN AND METHODS One hundred and seventy-seven patients with CHF and 66 subjects without CHF were included in this study. Plasma levels of S100A12 and high-sensitivity C-reactive protein (hs-CRP) were measured in all participants. After a follow-up period of 18months for CHF patients, major cardiovascular events (MCE), including cardiac death and rehospitalization for heart failure, were recorded. RESULTS Plasma levels of S100A12 were significantly higher in CHF patients than in control subjects (P<0.001) and positively correlated with hs-CRP (r=0.316, P<0.001). S100A12 levels were also higher in MCE patients than in MCE-free patients. The occurrence of MCE increased with advancing plasma S100A12 levels by stratification according to quartiles (Q4 vs Q1, P=0.015). Cox proportional hazards regression analysis revealed that S100A12 was an independent risk factor for MCE in CHF patients (P=0.009). CONCLUSIONS S100A12 is a potential biomarker of CHF that may provide important information regarding the prediction of MCE in patients with CHF.

Salubrinal attenuates right ventricular hypertrophy and dysfunction in hypoxic pulmonary hypertension of rats.

The phosphorylation of eukaryotic translation initiation factor 2 alpha (p-eIF2α) is essential for cell survival during hypoxia. The aim of this study was to investigate whether salubrinal, an inhibitor of p-eIF2α dephosphorylation could attenuate pulmonary arterial hypertension (PAH) and right ventricular (RV) hypertrophy in rats exposed to hypobaric hypoxia. PAH of rats was induced by hypobaric hypoxia. Salubrinal supplemented was randomized in either a prevention or a reversal protocol. At the end of the follow-up point, we measured echocardiography, hemodynamics, hematoxylin-eosin and Massons trichrome stainings. RNA-seq analysis is explored to identify changes in gene expression associated with hypobaric hypoxia with or without salubrinal. Compared with vehicle-treatment rats exposed to hypobaric hypoxia, salubrinal prevented and partly reversed the increase of the mean pulmonary artery pressure and RV hypertrophy. Whats more, salubrinal reduced the percentage wall thickness (WT%) of pulmonary artery and RV collagen volume fraction (CVF) in both prevention and reversal protocols. We also found that salubrinal was capable of reducing endoplasmic reticulum stress and oxidative stress. The result of RNA-seq analysis revealed that chronic hypoxia stimulated the differential expression of a series of genes involved in cell cycle regulation and ventricular hypertrophy and so on. Some of these genes could be ameliorated by salubrinal. These results indicate that salubrinal could prevent and reverse well-established RV remodeling, and restore the genes and pathways altered in the right ventricles of rats exposed to hypobaric hypoxia.