Tongxinluo Attenuates Myocardiac Fibrosis after Acute Myocardial Infarction in Rats via Inhibition of Endothelial-to-Mesenchymal Transition.

Endothelial-to-mesenchymal transition (EndMT) is an essential mechanism in myocardial fibrosis (MF). Tongxinluo (TXL) has been confirmed to protect the endothelium against reperfusion injury after acute myocardial infarction (AMI). However, whether TXL can inhibit MF after AMI via inhibiting EndMT remained unknown. This study aims to identify the role of EndMT in MF after AMI as well as the protective effects and underlying mechanisms of TXL on MF. The AMI model was established in rats by ligating left anterior descending coronary artery. Then, rats were administered with high- (0.8 g·kg-1·d-1), mid- (0.4 g·kg-1·d-1), and low- (0.2 g·kg-1·d-1) dose Tongxinluo and benazepril for 4 weeks, respectively. Cardiac function, infarct size, MF, and related indicators of EndMT were measured. In vitro, human cardiac microvascular endothelial cells (HCMECs) were pretreated with TXL for 4 h and then incubated in hypoxia conditions for 3 days to induce EndMT. Under this hypoxic condition, neuregulin-1 (NRG-1) siRNA were further applied to silence NRG-1 expression. Immunofluorescence microscopy was used to assess expression of endothelial marker of vWF and fibrotic marker of Vimentin. Related factors of EndMT were determined by Western blot analysis. TXL treatment significantly improved cardiac function, ameliorated MF, reduced collagen of fibrosis area (types I and III collagen) and limited excessive extracellular matrix deposition (mmp2 and mmp9). In addition, TXL inhibited EndMT in cardiac tissue and hypoxia-induced HCMECs. In hypoxia-induced HCMECs, TXL increased the expression of endothelial markers, whereas decreasing the expression of fibrotic markers, partially through enhanced expressions of NRG-1, phosphorylation of ErbB2, ErbB4, AKT, and downregulated expressions of hypoxia inducible factor-1a and transcription factor snail. After NRG-1 knockdown, the protective effect of TXL on HCMEC was partially abolished. In conclusion, TXL attenuates MF after AMI by inhibiting EndMT and through activating the NRG-1/ErbB- PI3K/AKT signalling cascade.

Qiliqiangxin Attenuates Oxidative Stress-Induced Mitochondrion-Dependent Apoptosis in Cardiomyocytes via PI3K/AKT/GSK3ß Signaling Pathway.

Qiliqiangxin capsule (QLQX) is a well-known traditional Chinese medicine that exhibits cardioprotective effects in heart failure patients. However, it remains unclear whether and by which mechanism QLQX attenuates oxidative stress-induced mitochondria-dependent myocardial apoptosis. In vivo, Sprague Dawley (SD) rats received left anterior descending coronary artery ligation for 4 weeks to establish a model of heart failure after acute myocardial infarction, and then were treated with QLQX for another 4 weeks. We evaluated cardiac function, oxidative stress injury, as well as the expressions of mitochondria-dependent apoptosis and its signaling factors. The results indicated that QLQX protected cardiac function and attenuated oxidative stress-induced myocardial apoptosis. Meanwhile, QLQX elevated the Bcl-2 expression, declined the expressions of Bax, cytochrome c, apoptotic protease activating factor-1 (Apaf-1), cleaved-caspase 9 and cleaved-caspase 3, and up-regulated the ratios of phospho-AKT/AKT and phospho-glycogen synthase kinase-3ß (GSK3ß)/GSK3ß. In vitro, H9c2 cardiomyocytes were pretreated with QLQX, then exposed to H2O2 for 24 h. QLQX promoted the proliferation of H9c2 cardiomyocytes induced by H2O2 and reversed oxidative stress damage. Moreover, QLQX inhibited the apoptosis rate and the pro-apoptosis protein expressions, but improved the Bcl-2 expression as well as the ratios of phospho-AKT/AKT and phospho-GSK3ß/GSK3ß. Meanwhile, it further ameliorated mitochondrion-related apoptosis by inhibiting the mitochondrial fission, mitochondrial permeability transition pore (MPTP) opening, and mitochondrial membrane potential (MMP) decline in H9c2 cardiomyocytes induced by H2O2. In addition, all the effects of QLQX on H2O2-induced mitochondria-dependent apoptosis could be blocked by the phosphoinositide 3-kinase (PI3K) inhibitor, LY294002. We conclude that QLQX may ameliorate oxidative stress-induced mitochondria-dependent apoptosis in cardiomyocytes through PI3K/AKT/GSK3ß signaling pathway.

LncRNA MALAT1 modulates ox-LDL induced EndMT through the Wnt/ß-catenin signaling pathway.

BACKGROUND: Endothelial-to-mesenchymal transition (EndMT) plays significant roles in atherosclerosis, but the regulatory mechanisms involving lncRNAs remain to be elucidated. Here we sort to identify the role of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in ox-LDL-induced EndMT. METHODS: The atherosclerosis model was established by feeding ApoE-/- mice with high-fat diet, and the levels of lncRNA MALAT1 in mouse arterial tissue were detected by RT-qPCR. Cell model was established by treating human umbilical vein endothelial cells (HUVECs) with ox-LDL, and the levels of EndMT markers, such as CD31, vWF, α-SMA and Vimentin and lncRNA MALAT1 levels were detected and their correlations were analyzed. The role of MALAT1 in EndMT and its dependence on Wnt/ß-catenin signaling pathway was further detected by knocking down or overexpressing MALAT1. RESULTS: MALAT1 was upregulated in high-fat food fed ApoE-/- mice. HUVECs treated with ox-LDL showed a significant decrease in expression of CD31 and vWF, a significant increase in expression of α-SMA and vimentin, and upregulated MALAT1. An increased MALAT1 level facilitated the nuclear translocation of ß-catenin induced by ox-LDL. Inhibition of MALAT1 expression reversed nuclear translocation of ß-catenin and EndMT. Moreover, overexpression of MALAT1 enhanced the effects of ox-LDL on HUVEC EndMT and Wnt/ß-catenin signaling activation. CONCLUSIONS: Our study revealed that the pathological EndMT required the activation of the MALAT1-dependent Wnt/ß-catenin signaling pathway, which may be important for the onset of atherosclerosis. TRIAL REGISTRATION: Not applicable.

Tongxinluo Regulates Expression of Tight Junction Proteins and Alleviates Endothelial Cell Monolayer Hyperpermeability via ERK-1/2 Signaling Pathway in Oxidized Low-Density Lipoprotein-Induced Human Umbilical Vein Endothelial Cells.

Vascular hyperpermeability resulting from distortion of endothelial junctions is associated with a number of cardiovascular diseases. Endothelial tight junction regulates the paracellular permeability of macromolecules, a function of Human Umbilical Vein Endothelial Cells (HUVEC) monolayers that can be regulated by oxidized Low-density Lipoprotein (ox-LDL). However, the understanding of drug regulation of vascular hyperpermeability is so far limited. This study thus aimed to investigate the role of Tongxinluo (TXL) in the maintenance of the vascular endothelial paracellular permeability. Here, changes in permeability were determined by measuring the paracellular flux of FITC-dextran 40000 (FD40), while protein expression and intercellular distribution were examined by western blot and immunofluorescence assay, respectively. We found that TXL alleviated the ox-LDL-induced increase in flux of FD40 and then reduced the hyperpermeability. Moreover, ox-LDL-induced disruptions of ZO-1, occludin, and claudin1 were also restored. This is via the activation of ERK1/2 in the vascular endothelial cells. Our results provide insights into the molecular mechanism by which TXL alleviates ox-LDL-induced hyperpermeability and provide the basis for further investigations of TXL as regulators of vascular barrier function.