Changwu Xu

Minocycline protects against myocardial ischemia and reperfusion injury by inhibiting high mobility group box 1 protein in rats

Minocycline has been shown to protect against myocardial ischemia and reperfusion injury. However, the mechanism remains unclear. This study was to investigate the role of high mobility group box 1 protein (HMGB1) in the cardioprotection of minocycline during myocardial ischemia and reperfusion in rats. Anesthetized male rats were once treated with minocycline (45 mg/kg, i.p.) 1h before ischemia, and then subjected to ischemia for 30 min followed by reperfusion for 4h. The lactate dehydrogenase (LDH), creatine kinase (CK) and infarct size were measured and the myocardial tissue apoptosis was assessed by TUNNEL assay. Neonatal rat ventricular myocytes were prepared and then cultured with recombinant HMGB1. Cell apoptosis was measured using an annexin V-FITC apoptosis detection kit. HMGB1 expression was assessed by immunoblotting. After 4h of reperfusion, minocycline could significantly decrease the infarct size, myocardium apoptosis and the levels of LDH and CK (all P<0.05). Meanwhile, minocycline could also significantly inhibit the HMGB1 expression during myocardial ischemia and reperfusion compared to that in ischemia and reperfusion group (P<0.05). In vitro, HMGB1 could significantly decrease the cell viability and promote the apoptosis of neonatal myocytes in a dose-dependent manner. The present study suggested that minocycline could protect against myocardial ischemia and reperfusion injury by inhibiting HMGB1 expression.

Increased serum HMGB1 is related to the severity of coronary artery stenosis

BACKGROUND High mobility group box 1 (HMGB1) protein has been identified as a novel pro-inflammatory cytokine in coronary artery disease (CAD). We investigated the relationship between serum HMGB1 level and the severity of coronary artery stenosis. METHODS Serum HMGB1 concentration in patients was measured by ELISA. All patients underwent coronary angiography and were assigned into groups according to the quartile of HMGB1 level. RESULTS HMGB1 level in USAP group was higher than that in control and SAP group. HMGB1 level in SAP group was higher than that in control group (p<0.05). Gensini scores in the highest quartile group (group IV), group III and group II were all significantly higher than that in the lowest quartile group (group I). There was significant correlation between angiographic Gensini score and serum level of HMGB1 (r=0.710, p<0.05). However, in subgroup analysis, we found that serum HMGB1 level was only correlated with angiographic Gensini score in SAP patients (r=0.786, p<0.05), but not USAP patients. CONCLUSIONS Serum HMGB1 level was markedly increased with the severity of coronary artery stenosis in patients with SAP and USAP, especially in SAP patients, which suggested that increased serum HMGB1 may involve in the pathogenesis of atherosclerotic CAD.

Resveratrol Attenuates Oxidative Stress Induced by Balloon Injury in the Rat Carotid Artery Through Actions on the ERK1/2 and NF-Kappa B Pathway

Background/Aim: Oxidative stress plays a critical role in pathogenesis of the neointimal arterial hyperplasia. The aim of the study was to evaluate effects of resveratrol (RSV) on the vascular hyperplasia stimulated by oxidative damage. Methods: Balloon vascular injury was induced in rats that were intraperitonealy exposed to resveratrol (1 mg/kg) on 7 or 14 days after surgical procedure. Animals were euthanized on 7 or 14 days after operation. The blood level of 8-iso-prostaglandin F2α, arterial morphology as well as expression of monocyte chemotactic protein-1 and interleukin-6 in carotid wall were measured. Vascular smooth muscle cells (VSMCs) were isolated from the thoracic aorta. Cellular proliferation and migration assays, reactive oxygen species (ROS), superoxide dismutase (SOD) and NADPH oxidative activity, protein level of β-actin, histone H3, NF-ĸB p65, IĸB, ERK1/2, phospho-ERK1/2, phospho-p38 as well as NF-ĸB transcription activity were evaluated in-vitro after angiotensin II stimulation and resveratrol (50-200 µmol/L) treatment. Results: Significant decreases in neointimal/medial area, serum prostaglandin level and genes expression were found in rats treated with resveratrol, when compared to the control group. Significant changes were also revealed for proliferation and migration rates, ROS level, as well as SOD, NADPH oxidase, ERK1/2 phosphorylation and NF-ĸB transcriptional activity in cell cultures exposed to highest dose of resveratrol. Insignificant changes were observed for NF-kappaB p65 translocation and IĸB degradation, p38 phosphorylation in MAPK pathway. Conclusion: Resveratrol significantly suppressed the neointimal hyperplasia after balloon injury through inhibition of oxidative stress and inflammation by blocking the ERK1/2/NF-kappa B pathway.

Inhibition of neointimal hyperplasia in the rat carotid artery injury model by a HMGB1 inhibitor

OBJECTIVE High mobility group box 1 protein (HMGB1) is expressed in atherosclerotic lesions. However, its role in vascular system is unknown. In this study, we explore whether the inhibition of HMGB1 attenuates neointimal formation in animal models. METHODS AND RESULTS Experiments were performed with VSMCs from thoracic aorta of SD rats in vitro, and a rat carotid artery balloon injury model in vivo. HMGB1 levels were increased after stimulation of angiotensin II (Ang II) and 10% serum in cultured VSMCs. HMGB1 inhibitor (glycyrrhizin) significantly inhibited the proliferation and migration of Ang II-treated VSMCs, which was accompanied with decreased oxidative stress and inflammation. The underlying mechanisms were related with the promotion of antioxidant systems activity and deactivation of p38 MAPK/NF-κB signaling pathway, respectively. Furthermore, inhibition of HMGB1 blunted Notch signaling pathway during VSMCs phenotypic transition, and correspondingly restored VSMCs differentiated phenotype under 10% serum stimulation. In vivo study, HMGB1 expression was elevated after artery injury. Meanwhile, glycyrrhizin treatment suppressed HMGB1 expression, which was accompanied with blunted inflammation and oxidative stress after 7 days of balloon injury. Moreover, the area of neointimal to media area ratio was significantly decreased in glycyrrhizin group compared with injury group at 14 days after balloon injury. CONCLUSIONS Inhibition of HMGB1 activity attenuated VSMCs activation and neointimal formation after carotid injury. Therefore, blockage of HMGB1 might represent a novel therapeutic strategy for vascular injury.

Anti‑inflammatory effect of sodium butyrate preconditioning during myocardial ischemia/reperfusion

High mobility group box 1 protein (HMGB1) has an important role in myocardial ischemia/reperfusion (I/R) injury. Sodium butyrate, an inhibitor of histone deacetylase, has been shown to inhibit HMGB1 expression. In the present study, the effect of sodium butyrate on myocardial I/R injury in rats was investigated. Anesthetized male rats were intraperitoneally administered sodium butyrate (100 or 300 mg/kg) 30 min prior to the induction of ischemia. The rats were then subjected to ischemia for 30 min followed by reperfusion for 4 h. Infarct size, lactate dehydrogenase (LDH), creatine kinase (CK) and superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels were then measured. The expression of HMGB1 was assessed using western blot analysis. The results demonstrated that pretreatment with sodium butyrate (300 mg/kg) significantly reduced the infarct size, as well as the levels of LDH and CK (P<0.05). In addition, sodium butyrate (300 mg/kg) was shown to significantly inhibit the I/R-induced increase in the level of MDA and reduction in the level of SOD (P<0.05). Furthermore, treatment with sodium butyrate (300 mg/kg) was found to significantly inhibit the expression of TNF-α, IL-6 and HMGB1 induced by I/R injury (P<0.05). In conclusion, the results from the present study suggest that preconditioning with sodium butyrate may attenuate myocardial I/R injury by inhibition of the expression of inflammatory mediators during myocardial I/R.

Preconditioning with high mobility group box 1 protein protects against myocardial ischemia–reperfusion injury

Abstract Objective To investigate whether preconditioning with high mobility group box 1 protein (HMGB1) could reduce myocardial ischemia–reperfusion (I/R) injury. Methods and results Infarct size, lactate dehydrogenase (LDH), creatine kinase (CK), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were assessed. HMGB1 preconditioning reduced significantly the infarct size induced by I/R. The LDH, CK, TNF-α and IL-6 levels were significantly decreased by HMGB1 preconditioning compared to those in the I/R group. Conclusion The present study suggested that preconditioning with HMGB1 could induce HMGB1 tolerance and protect against myocardial I/R injury.

Exogenous High-Mobility Group Box 1 Protein Injection Improves Cardiac Function after Myocardial Infarction: Involvement of Wnt Signaling Activation

Exogenous high-mobility group box 1 protein (HMGB1) injection could prevent left ventricular remodeling and enhance left ventricular function during myocardial infarction (MI). However, the mechanism remains unclear. This paper was to investigate in the mechanism of cardioprotection of HMGB1 during MI in rats. Anesthetized male rats were treated once with HMGB1 (200 ng) 4 h after MI and then executed after 7 and 28 days, respectively. Cardiac function, collagen deposition, and dishevelled-1 and β-catenin protein expression were measured. After MI 7 days or 28 days, the left ventricular ejection fraction (LVEF) was significantly decreased compared to that of sham-operated control group (P < 0.05). However, the LVEF HMGB1-treated groups were significantly higher compared to those of the MI group in both 7 days and 28 days (P < 0.05). The collagen volume fraction was significantly reduced in the HMGB1-treated group in infarcted border zone. HMGB1 could activate the expression of dishevelled-1 and β-catenin proteins (P < 0.05). Our study suggested that exogenous high-mobility group box 1 protein injection improves cardiac function after MI, which may be involved in Wnt/β-catenin signaling activation.

Minocycline attenuates ischemia-induced ventricular arrhythmias in rats

Minocycline has been shown to protect against myocardial ischemia-reperfusion injury. This study investigated the effects of minocycline on ischemia-induced ventricular arrhythmias in rats. Anesthetized male rats were once treated with minocycline (45mg/kg, i.p.) 1h before ischemia in the absence and/or presence of 2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one hydrochloride (LY294002, 0.3mg/kg, i.v., a PI3K inhibitor) and 5-hydroxydecanoic acid [5-HD, 10mg/kg, i.v., a specific inhibitor of mitochondrial ATP-sensitive potassium (K(ATP)) channels] which were once injected 10min before ischemia and then subjected to ischemia for 30min. Ventricular arrhythmias were assessed. L-type Ca(2+) current was measured by the patch-clamp technique. During the 30-minute ischemia, minocycline significantly reduced the incidence of ventricular fibrillation (VF) (P<0.05). The duration of VT+VF, the number of VT+VF episodes and the severity of arrhythmias were all significantly reduced by minocycline compared to those in myocardial ischemia group (P<0.05 for all). Administration of LY294002 or 5-HD abolished the protective effects of minocycline on VF incidence, the duration of VT+VF, the number of VT+VF episodes and the severity of arrhythmias (P<0.05 for all). In addition, minocycline inhibited L-type Ca(2+) currents of normal myocardial cell membrane in a dose-dependent manner. This study suggested that minocycline could attenuate ischemia-induced ventricular arrhythmias in rats in which PI3K/Akt signaling pathway, mitochondrial K(ATP) channels and L-type Ca(2+) channels may be involved.

Similarities between ischemic preconditioning and postconditioning in myocardial ischemia/reperfusion injury

Abstract Objective To determine whether a combination of ischemic preconditioning (IPreC) and ischemic postconditioning (IPostC) provided synergistic protection in myocardial ischemia/reperfusion injury. Methods and results IPreC and IPostC could not provide synergistically protective effects on reducing infarct size, inhibiting the increase of lactate dehydrogenase, creatine kinase and malondialdehyde and inhibiting the decrease of superoxide dismutase, and inhibiting myocardium apoptosis induced by ischemia/reperfusion. Conclusion The present study indicated that the combination of IPreC and IPostC could not provide a synergistic protection in myocardial 1ischemia/reperfusion injury, they may share common signaling pathways.

IOX1, a JMJD2A inhibitor, suppresses the proliferation and migration of vascular smooth muscle cells induced by angiotensin II by regulating the expression of cell cycle-related proteins

The epigenetic modification of vascular smooth muscle cell (VSMC) phenotypic switching, proliferation, migration, apoptosis and extracellular matrix synthesis is known to occur in atherosclerosis. The aim of the present study was to investigate the effects of IOX1, a Jumonji domain-containing 2A (JMJD2A) inhibitor, on regulation of the cell cycle in angiotensin II (Ang II)-stimulated VSMCs and to elucidate the possible mechanisms involved. The proliferation and migration of the Ang II-stimulated VSMCs in the presence or absence of IOX1 were evaluated in vitro. Flow cytometric analysis was used to determine the effects of IOX1 on cell cycle progression. RT-qPCR and western blot analysis were carried out to measure the expression levels of cell cycle-related genes. The trimethylation of histone H3 lysine 9 (H3K9me3) at the promoters of these genes was detected by chromatin immunoprecipitation (ChIP) assay. We confirmed that the JMJD2A levels were increased, whereas the H3K9me3 levels were decreased in the Ang II-stimulated VSMCs. The inhibition of JMJD2A by IOX1 suppressed the Ang II-induced cell proliferation, migration and cell cycle progression by inhibiting cyclin D1 expression and increasing p21 expression. The underlying mechanisms were related to the restoration of the H3K9me3 levels at the promoters of these genes. In conclusion, the findings of our study indicate that IOX1 exerts its anti-proliferative and anti-migratory effects by regulating the expression of the cell cycle-related proteins, cyclin D1 and p21.