Jinyu Chi

Cyclosporin A induces apoptosis in H9c2 cardiomyoblast cells through calcium-sensing receptor-mediated activation of the ERK MAPK and p38 MAPK pathways.

The cardiotoxicity of cyclosporine A (CsA) limits its clinical application in extensive and long-term therapies. Our group has shown that CsA induces myocardium cell apoptosis in vivo and increases calcium-sensing receptor (CaSR) expression. However, its molecular mechanism remains unknown. The purpose of this study was to determine whether CaSR plays an essential role in CsA-induced apoptosis in H9c2 cells and to investigate the role of the mitogen-activated protein kinase (MAPK) signaling cascade in this process. H9c2 cells were treated with CsA in a dose-dependent manner, and decreased Bcl-2 expression, increased Bax expression, and caspase-3 activation were observed. In a time-dependent manner, CsA increased CaSR expression, activated the extracellularly regulated kinase (ERK) and p38 MAPK pathways, and inactivated the c-Jun N-terminal kinase (JNK) MAPK signaling pathway. When H9c2 cardiomyoblast cells pretreated with gadolinium chloride (GdCl3), a CaSR activator, were treated with CsA, decreased phosphorylation of ERK1/2, increased phosphorylation of p38, decreased Bcl-2 expression, increased Bax expression, and activated caspase-3 were observed. Cells pretreated with the CaSR inhibitor NPS2390 inhibited this process. Furthermore, the MEK1/2 inhibitor U0126 and the p38 MAPK inhibitor SB203580 markedly blocked the effect of CsA on cell apoptosis, apoptotic-related protein expression, and caspase-3 activation. These findings showed that CsA induced apoptosis in H9c2 cells in vitro, and CaSR mediated the degradation of ERK MAPK and the upregulation of the p38 MAPK pathway involved in CsA-induced H9c2 cardiomyoblast cell apoptosis.

Activation in M1 but not M2 Macrophages Contributes to Cardiac Remodeling after Myocardial Infarction in Rats: a Critical Role of the Calcium Sensing Receptor/NRLP3 Inflammasome.

Aims: Macrophage (MΦ) infiltration during myocardial infarction (MI) amplifies cardiac inflammation and remodeling. We investigated whether activation of the NRLP3 inflammasome by a calcium sensing receptor (CaSR) in MΦ subsets contributes to cardiac remodeling following MI. Methods and Results: Infiltrated MΦ exhibited biphasic activation after MI; M1MΦ peaked at MI 3d and decreased until MI 14d, whereas M2MΦ peaked at MI 7d and decreased at MI 14d as shown via immunohistochemistry. IL-1β co-infiltrated with both M1MΦ and M2MΦ; IL-1β exhibited the same infiltrating tendency as M1MΦ, which was detected by immunohistochemistry. Increasing ventricular fibrosis was confirmed by Masson staining. CaSR and NLRP3 inflammasome in the MI group were upregulated in MΦ subsets in myocardium and peritoneal MΦ (p-MΦ) compared with the sham groups which were detected by immunofluorescence and western blotting. CaSR-activated NLRP3 inflammasome played a role in M1MΦ via PLC-IP3 but did not play a role in M2MΦ which were polarized by the THP-1 as shown by western blotting and intracellular calcium measurement. CaSR/NLRP3 inflammasome activation in M1MΦ led to the following effects: upregulated α-sma, MMP-2 and MMP-9, and collagen secretion; and downregulated TIMP-2 in cardiac fibroblasts via IL-1β-IL-1RI, which was detected by coculturing M1MΦ and cardiac fibroblasts. Conclusions: We suggest that the CaSR/NLRP3 inflammasome plays an essential role via the PLC-IP3 pathway in M1MΦ to promote cardiac remodeling post-MI in rats, including accelerated cardiac fibroblast phenotypic transversion, increased collagen and extracellular matrix (ECM) secretion; however, the CaSR/NLRP3 inflammasome does not play a role in this process in M2MΦ.

Knockdown of dishevelled-1 attenuates cyclosporine A-induced apoptosis in H9c2 cardiomyoblast cells

Cyclosporine (CsA) has become a mainstay for immune suppression of organ transplants. It is known that patients receiving CsA manifest increased growth of aggressive cardiotoxicity. We have demonstrated that CsA induces myocardium cell apoptosis in vivo and vitro. Recently, dishevelled-1 (Dvl-1) protein, which is a cytoplasmic mediator of Wnt/β-catenin signaling, was explored in cardiac diseases. However, whether Dvl-1 is involved in CsA-induced apoptosis remains to be determined. The aim of this study was to explore the role of Dvl-1 in CsA-induced apoptosis in H9c2 cardiomyoblast cells and to investigate the role of the Wnt/β-catenin signaling cascade in this progress. H9c2 cells were treated with CsA in dose and time-dependent manners. We found that the appropriate concentrations and time-points of CsA-induced the expression of Dvl-1 and subsequent up-regulation of β-catenin and c-Myc, which is consistent with previously demonstrated concentrations and time-points when H9c2 cells apoptosis occurred. Then, cells were transfected with small interfering RNA (siRNA) against Dvl-1 and stimulated with previously demonstrated concentration of CsA. Dvl-1 down-regulation decreased the apoptotic rate, caspase-3 activity, and the Bax/Bcl-2 ratio in H9c2 cells treated with CsA. Furthermore, knocking down the expression of Dvl-1 partially suppressed the activity of the Wnt/β-catenin pathway. Moreover, we further deleted the downstream member β-catenin by specific siRNA, and found that CsA-induced the Bax/Bcl-2 ratio and the expression of c-Myc, which were attenuated. Our results are the first to unveil this novel aspect of Dvl-1 signaling. In addition, these data provide insight into the pathogenesis and the therapeutic strategies of CsA-induced myocardial injury.

Adenovirus-mediated tissue factor pathway inhibitor gene transfer induces apoptosis by blocking the phosphorylation of JAK-2/STAT-3 pathway in vascular smooth muscle cells.

OBJECTIVE In our previous study, we have demonstrated that tissue factor pathway inhibitor (TFPI) gene could induce vascular smooth muscle cell (VSMC) apoptosis. This study was conducted to investigate whether the overexpression of the TFPI gene can induce VSMC apoptosis by inhibiting JAK-2/STAT-3 pathway phosphorylation and thereby inhibiting the expression of such downstream targets as the apoptotic protein Bcl-2 and cell cycle protein cyclin D1. The effect of TFPI on the expression of survivin, a central molecule in cell survival, was also investigated. METHODS Rat VSMCs were infected with recombinant adenovirus containing either the TFPI (Ad-TFPI) or LacZ (Ad-LacZ) gene or DMEM in vitro. TFPI expression was detected by ELISA. TUNEL staining and electron microscope were carried out to determine the apoptosis of VSMCs. The expression levels of JAK-2, p-JAK-2, STAT-3, p-STAT-3, cyclin D1, Bcl-2 and survivin were examined by western blot analysis. RESULTS TFPI protein was detected in the TFPI group after gene transfer and the peak expression was at the 3rd day. At the 3rd, 5th and 7th days after gene transfer, the apoptotic rates by TUNEL assay in the TFPI group were 10.91 ± 1.66%, 13.46 ± 1.28% and 17.04 ± 1.95%, respectively, whereas those in the LacZ group were 3.28 ± 0.89%, 4.01 ± 0.72% and 4.89 ± 1.17%, respectively. We observed cell contraction, slight mitochondrial swelling, nuclear pyknosis and apoptotic body formation in TFPI-treated VSMCs using electron microscopy. JAK-2, p-JAK-2, STAT-3, p-STAT-3, cyclin D1 and Bcl-2, which are all involved in the JAK-2/STAT-3 pathway, were detected in the VSMCs on the 3rd, 5th and 7th days after gene transfer, which is consistent with previously demonstrated time points when VSMCs apoptosis occurred. The expression levels of p-JAK-2, p-STAT-3, cyclin D1 and Bcl-2 were significantly decreased over time in the TFPI group (each P<0.05) but not in the Ad-LacZ and DMEM groups. However, this attenuation of expression was not observed for JAK-2 and STAT-3 in any of the groups at any time points after gene transfer (each P>0.05). The expression level of survivin in the TFPI group also weakened significantly over time compared with the levels in the Ad-LacZ and DMEM groups (each P<0.05) at the 3rd, 5th and 7th days after gene transfer. CONCLUSION The results demonstrated that TFPI played an apoptosis-inducing role in VSMCs in a manner that involves both the suppression of JAK-2/STAT-3 pathway phosphorylation and the down-regulation of survivin. Our data show for the first time that targeting the JAK-2/STAT-3 pathway and survivin by overexpressing TFPI may be a new avenue for the treatment of restenosis.

H3 Relaxin Protects Against Myocardial Injury in Experimental Diabetic Cardiomyopathy by Inhibiting Myocardial Apoptosis, Fibrosis and Inflammation

Background/Aims: Apoptosis, fibrosis and NLRP3 inflammasome activation are involved in the development of diabetic cardiomyopathy (DCM). Human recombinant relaxin-3 (H3 relaxin) is a novel bioactive peptide that inhibits cardiac injury; however, whether H3 relaxin prevents cardiac injury in rats with DCM and the underlying mechanisms are unknown. Methods: To investigate the effect of H3 relaxin on DCM, we performed a study using H3 relaxin treatment in male Sprague-Dawley (SD) rats with streptozotocin (STZ)-induced diabetes (DM). We measured apoptosis, fibrosis and NLRP3 inflammasome markers in the rat hearts four and eight weeks after the rats were injected with STZ (65 mg/kg) by western blot analysis. Subsequently, 2 or 6 weeks after the STZ treatment, the rats were treated with H3 relaxin [2 µg/kg/d (A group) or 0.2 µg/kg/d (B group)] for 2 weeks. Cardiac function was evaluated by echocardiography to determine the extent of myocardial injury in the DM rats. The protein levels of apoptosis, fibrosis and NLRP3 inflammasome markers were used to assess myocardial injury. In addition, we determined the plasma levels of IL-1β and IL-18 using a Milliplex MAP Rat Cytokine/Chemokine Magnetic Bead Panel kit. Results: The protein expression of cleaved caspase-8, caspase-9 and caspase-3 as well as fibrosis markers increased at 4 and 8 weeks in the STZ-induced diabetic hearts compared with the levels in the control group. Furthermore, the NLRP3 inflammasome was substantially activated in STZ-induced diabetic hearts, leading to increased IL-1β and IL-18 levels. Compared with the DM group, the A group exhibited substantially better cardiac function. The protein levels of apoptosis markers were attenuated by H3 relaxin, indicating that H3 relaxin inhibited myocardial apoptosis in the hearts of diabetic rats. The protein expression of fibrosis markers was inhibited by H3 relaxin. Additionally, the protein expression and activation of the NLRP3 inflammasome were also effectively attenuated by H3 relaxin. Conclusions: This study is the first to demonstrate that H3 relaxin plays an anti-apoptotic, anti-fibrotic and anti-inflammatory role in DCM.

Role of the calcium sensing receptor in cardiomyocyte apoptosis via mitochondrial dynamics in compensatory hypertrophied myocardium of spontaneously hypertensive rat

Calcium sensing receptor (CaSR) mediates pathological cardiac hypertrophy. Mitochondria maintain their function through fission and fusion and disruption of mitochondrial dynamic is linked to various cardiac diseases. This study examined how inhibition of CaSR by the inhibitor Calhex231 affected the mitochondrial dynamics in a hypertensive model in rats. Spontaneously hypertensive rats (SHRs) and Wistar Kyoto (WKY) rats were used in this study. Cardiac function and blood pressure was evaluated at the end of the study. SHRs showed increases in the ratio of heart weight to body weight and the levels of CaSR; all of these increases were suppressed by Calhex231. Additionally, Calhex231 treatment of SHRs changed the expression of proteins involved in mitochondrial dynamics. Our results demonstrated that CaSR activation induced cardiomyocyte apoptosis through the mitochondrial dynamics mediated apoptotic pathway in hypertensive hearts.

Tissue factor pathway inhibitor gene transfer prevents vascular smooth muscle cell proliferation by interfering with the MCP-3/CCR2 pathway.

Increased vascular smooth muscle cell (VSMC) proliferation substantially contributes to the pathogenesis of atherosclerosis and intimal hyperplasia after vascular injury. The importance of inflammation in VSMC proliferation is now being recognized. Preventing the inflammatory response is one therapeutic strategy that can be used to inhibit atherosclerosis in the clinic. The present study, using RNA interference and gene transfer techniques, was conducted to investigate the effect of monocyte chemotactic protein-3 (MCP-3) on VSMC proliferation that is a result of TNF-α stimulation, and whether overexpression of the tissue factor pathway inhibitor (TFPI) gene could prevent VSMC proliferation by blocking the MCP-3/CC chemokine receptor 2 (CCR2) pathway. Mouse VSMCs were infected in vitro with recombinant adenoviruses containing either mouse MCP-3-shRNA (Ad-MCP-3-shRNA), the TFPI gene (Ad-TFPI), or the negative control, which was shRNA encoding the sequence for EGFP (Ad-EGFP) or DMEM only. The cells were then stimulated with TNF-α for different time periods on the third day after gene transfer. The data show that VSMC proliferation in the Ad-MCP-3-shRNA and Ad-TFPI groups was markedly decreased using BrdU ELISA and MTT assays; MCP-3-shRNA and TFPI inhibited the expression of MCP-3 and CCR2 after long-term stimulation and inhibited the phosphorylation of ERK1/2 and AKT after short-term stimulation, as shown by ELISA and western blot analysis. This study provides convincing evidence that clarifies the effect of the proinflammatory factor MCP-3 in promoting VSMC proliferation. Our data also show, for the first time, that TFPI has an anti-proliferative role in TNF-α stimulated-VSMCs at least partly by interfering with the MCP-3/CCR2 pathway and then via suppression of the ERK1/2 and PI3K/AKT signaling pathways. We conclude that TFPI gene transfer may be a safe and effective therapeutic tool for treating atherosclerosis and intimal hyperplasia.

Cyclosporin A induces autophagy in cardiac fibroblasts through the NRP-2/WDFY-1 axis

Cyclosporin A (CsA) is an effective immunosuppressive agent, but its myocardial toxicity limits its widespread and long-term clinical application. In this study, CsA treatment led to damages in myocardial fiber structure, an increase in myocardial fibrosis, and changes in heart size and shape; moreover, the degree of damage was exacerbated with prolonged drug application and increases in dose. However, the mechanism is not clear; therefore, the purpose of this study was to reveal the mechanism of CsA-induced myocardial fibrosis and identify a new target for the prevention and treatment of CsA-induced myocardial injury. Cardiac fibroblasts were treated with CsA (5, 10, or 20 μg/mL) for 24 h. Autophagy was observed by electron microscopy and immunofluorescence. The expression of NRP-2/WDFY-1, autophagy-related proteins (Beclin1 and LC3B), fibrosis-related proteins (MMP2/9), and fibroblast phenotype conversion factor (α-SMA) was evaluated by Western blot. The expression of collagen I was determined by ELISA. Then, we used the gene interference technique to alter WDFY-1 expression with or without CsA or 3-MA treatment for 24 h, and the effects on autophagy and the expression of autophagy-related proteins, fibrosis-associated proteins, IFN-α, TNF-α, and IL-6 were determined. The results showed the following: (1) CsA induced fibrosis-related protein (MMP2/9), fibroblast phenotype conversion factor (α-SMA), and collagen I up-regulation in a dose-dependent manner. (2) CsA induced the formation of autophagosomes and up-regulated the expression of Beclin1, LC3B, and the ERK/MAPK pathway in cardiac fibroblasts. (3) CsA induced NRP-2 down-regulation and WDFY-1 up-regulation. (4) Depletion of WDFY-1 inhibited CsA-induced autophagy, TNF-α and IFN-α up-regulation, and fibrosis. (5) The autophagy inhibitor 3-MA inhibited CsA-induced TNF-α and IFN-α up-regulation and fibrosis. Overall, cyclosporin A induces autophagy in cardiac fibroblasts through the NRP-2/WDFY-1 axis, which promotes the progression of myocardial fibrosis.

Cortistatin inhibits arterial calcification in rats via GSK3ß/ß-catenin and protein kinase C signalling but not c-Jun N-terminal kinase signalling.

Cortistatin (CST) is a newly discovered endogenous active peptide that exerts protective effects on the cardiovascular system. However, the relationship between CST and aortic calcification and the underlying mechanism remain obscure. Therefore, we investigated effects of CST on aortic calcification and its signalling pathways.