Simvastatin Mitigates Apoptosis and Transforming Growth Factor-Beta Upregulation in Stretch-Induced Endothelial Cells

New Dawn for Atherosclerosis: Vascular Endothelial Cell Senescence and Death

Endothelial cells (ECs) form the inner linings of blood vessels, and are directly exposed to endogenous hazard signals and metabolites in the circulatory system. The senescence and death of ECs are not only adverse outcomes, but also causal contributors to endothelial dysfunction, an early risk marker of atherosclerosis. The pathophysiological process of EC senescence involves both structural and functional changes and has been linked to various factors, including oxidative stress, dysregulated cell cycle, hyperuricemia, vascular inflammation, and aberrant metabolite sensing and signaling. Multiple forms of EC death have been documented in atherosclerosis, including autophagic cell death, apoptosis, pyroptosis, NETosis, necroptosis, and ferroptosis. Despite this, the molecular mechanisms underlying EC senescence or death in atherogenesis are not fully understood. To provide a comprehensive update on the subject, this review examines the historic and latest findings on the molecular mechanisms and functional alterations associated with EC senescence and death in different stages of atherosclerosis.

Mechanical stress induced EndoMT in endothelial cells through PPARγ downregulation

Portal hypertension is a group of clinical syndromes induced by increased portal system pressure due to various etiologies including cirrhosis. When portal hypertension develops, the portal vein dilates and endothelial cells (ECs) in the portal vein are subjected to mechanical stretch. In this study, elastic silicone chambers were used to simulate the effects of mechanical stretch on ECs under portal hypertension. We found that mechanical stretch decreased PPARγ expression in ECs by blocking the PI3K/AKT/CREB signaling pathway or increasing NEDD4-mediated ubiquitination and degradation of PPARγ. Moreover, PPARγ downregulation triggered Endothelial-to-mesenchymal transition (EndoMT) in ECs under stretch by promoting Smad3 phosphorylation. The PPARγ agonist rosiglitazone mitigated stretch-induced EndoMT in vitro and alleviated EndoMT of the portal vein endothelium in cirrhotic rats.

Platelet-derived TGF-β1 is related to portal vein thrombosis in cirrhosis by promoting hypercoagulability and endothelial dysfunction

Background

Portal vein thrombosis (PVT) is a serious complication of cirrhosis accompanied by unclear pathogenesis. Transforming growth factor-beta (TGF-β) has been implicated in atherosclerosis and venous thrombosis whereas study regarding its part in PVT is lacking. The aim of this study was to explore the role of cytokine TGF-β1 in PVT and the potential mechanism.

Materials and methods

We included patients with cirrhotic gastroesophageal varices and divided them into two groups according to the presence of PVT. Serum levels of TGF-β1 were detected using Cytometric Bead Array kit and compared between two groups. Coagulation status was assessed using thromboelastography (TEG). Primary liver sinusoidal endothelial cells were treated with TGF-β1 and evaluated for endothelial dysfunction by RT-PCR.

Results

Our results uncovered that TGF-β1 (6,866.55 vs. 3,840.60 pg/ml, P = 0.015) significantly increased in the PVT group. Splenectomy might promote PVT by increasing platelet-derived TGF-β1 levels. Other cytokines showed no difference between PVT and non-PVT groups. Besides, TGF-β1 was correlated with platelet, fibrinogen, TEG-CI, TEG-MA, and TEG-α (coef = 0.733, 0.494, 0.604, 0.608, and 0.511; P < 0.001, 0.027, 0.004, 0.004, and 0.021, respectively), which indicated a hypercoagulable state in PVT patients. RT-PCR of liver sinusoidal endothelial cells showed a markable increment of von Willebrand Factor (vWF), thrombomodulin(TM), intercellular adhesion moleclar-1(ICAM-1), and vascular endothelial growth factor(VEGF) after TGF-β1 treatment, suggesting the involvement of endothelial dysfunction.

Conclusion

Elevated platelet-derived TGF-β1 exhibited association with hypercoagulability and promoting effect on endothelial dysfunction, closely related with PVT in cirrhotic patients.

Notch signaling regulates strain-mediated phenotypic switching of vascular smooth muscle cells

Mechanical stimuli experienced by vascular smooth muscle cells (VSMCs) and mechanosensitive Notch signaling are important regulators of vascular growth and remodeling. However, the interplay between mechanical cues and Notch signaling, and its contribution to regulate the VSMC phenotype are still unclear. Here, we investigated the role of Notch signaling in regulating strain-mediated changes in VSMC phenotype. Synthetic and contractile VSMCs were cyclically stretched for 48 h to determine the temporal changes in phenotypic features. Different magnitudes of strain were applied to investigate its effect on Notch mechanosensitivity and the phenotypic regulation of VSMCs. In addition, Notch signaling was inhibited via DAPT treatment and activated with immobilized Jagged1 ligands to understand the role of Notch on strain-mediated phenotypic changes of VSMCs. Our data demonstrate that cyclic strain induces a decrease in Notch signaling along with a loss of VSMC contractile features. Accordingly, the activation of Notch signaling during cyclic stretching partially rescued the contractile features of VSMCs. These findings demonstrate that Notch signaling has an important role in regulating strain-mediated phenotypic switching of VSMCs.

Increased PD-L1 Restricts Liver Injury in Nonalcoholic Fatty Liver Disease

PD-L1 is a critical checkpoint that protects tissues from autoimmune injury. Nevertheless, the role of PD-L1 in nonalcoholic fatty liver disease- (NAFLD-) induced liver damage is still unclear. In this study, we examined the role and mechanism of PD-L1 expression on NAFLD-induced liver damage in vitro and in vivo. PD-L1 expression in the livers from patients with NAFLD, and LO2 cells treated by FFA, was significantly increased. FFA triggers a large amount of ROS (generated from NOX4 and damaged mitochondria), promoting the ZNF24 expression and suppressing ZN24 sumoylation, both of which enhance the PD-L1 transcription and expression. The knockdown of PD-L1 increases CD8 + T cells' damage to FFA-treated LO2 cells, while its upregulation limits the liver injury in NAFLD models. Collectively, we demonstrate that FFA promotes PD-L1 expression through the ROS/ZNF24 pathway and suppresses UBE2I-mediated ZNF24 sumoylation to enhance its transcriptional activity of PD-L1. PD-L1 upregulation limits FFA-induced injury of hepatocytes in vitro and in vivo.

Relationship between portal vein width and portal vein thrombosis in patients with hepatitis B cirrhosis

BACKGROUND

The early diagnosis of portal vein thrombosis (PVT) is still a difficult clinical problem. There is an urgent need to find noninvasive indexes that can predict PVT.

AIM

To investigate the relationship between portal vein width and PVT.

METHODS

A total of 418 patients with hepatitis B cirrhosis were collected. They were divided into a PVT group (n = 66) and a non-PVT group (n = 352) according to whether PVT occurred. The general data of the two groups were compared, and the risk factors affecting PVT were analyzed retrospectively by multivariate logistic regression. The effectiveness of different risk factors in predicting PVT was evaluated by receiver operating characteristic (ROC) curve analysis.

RESULTS

Compared with the non-PVT group, the PVT group had a significantly higher Child-Pugh score, lower rate of Child-Pugh A class, higher platelet count and D-dimer level, wider portal vein width, and slower portal vein blood flow (P < 0.05). Logistic regression showed that portal vein width (odds ratio [OR] = 3.941, P = 0.001), portal vein blood flow (OR = 0.841, P = 0.007), platelet count (OR = 1.024, P = 0.008), and D-dimer level (OR = 2.383, P = 0.000) were independent risk factors for PVT in patients with liver cirrhosis. The maximum area under the ROC curve of portal vein width in the diagnosis of PVT was 0.874, and the best diagnostic threshold was > 12.5 mm, with a predictive sensitivity and specificity of 78% and 82%, respectively.

CONCLUSION

The increase of portal vein diameter is a risk factor for PVT in patients with liver cirrhosis.

Arctigenin attenuates paraquat-induced human lung epithelial A549 cell injury by suppressing ROS/p38 mitogen-activated protein kinases-mediated apoptosis

BACKGROUND

Paraquat (PQ)-induced acute lung injury (ALI) and pulmonary fibrosis are common diseases with high mortality but without effective antidotes in emergency medicine. Our previous study has proved that arctigenin suppressed pulmonary fibrosis induced by PQ. We wondered whether arctigenin could also have a protective effect on PQ-induced ALI.

METHODS

A PQ-induced A549 cell injury model was used, and the effect of arctigenin was determined by a cell counting kit-8 (CCK-8) cell viability assay. In addition, terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labelling (TUNEL) staining assays and mitochondrial membrane potential assays were performed to evaluate the level of cell apoptosis. The generation of reactive oxygen species (ROS) was reflected by dihydroethidium (DHE) staining and a 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) assay. Moreover, immunoblotting studies were used to assess the expression of mitogen-activated protein kinases (MAPKs) and p38 MAPK.

RESULTS

Arctigenin attenuated PQ-induced inhibition of A549 cell viability in a dose-dependent manner. Arctigenin also significantly reduced PQ-induced A549 cell apoptosis, as reflected by the TUNEL assay and mitochondrial membrane potential assay, which may result from suppressed ROS/p38 MAPK signaling because we found that arctigenin dramatically suppressed ROS generation and p38 MAPK phosphorylation.

CONCLUSION

Arctigenin could attenuate PQ-induced lung epithelial A549 cell injury in vitro by suppressing ROS/p38 MAPK-mediated cell apoptosis, and arctigenin might be considered a potential candidate drug for PQ-induced ALI.

Mechanism of cell death of endothelial cells regulated by mechanical forces

Cell death of endothelial cells (ECs) is a common devastating consequence of various vascular-related diseases. Atherosclerosis, hypertension, sepsis, diabetes, cerebral ischemia and cardiac ischemia/reperfusion injury, and chronic kidney disease remain major causes of morbidity and mortality worldwide, in which ECs are constantly subjected to a great amount of dynamic changed mechanical forces including shear stress, extracellular matrix stiffness, mechanical stretch and microgravity. A thorough understanding of the regulatory mechanisms by which the mechanical forces controlled the cell deaths including apoptosis, autophagy, and pyroptosis is crucial for the development of new therapeutic strategies. In the present review, experimental and clinical data highlight that nutrient depletion, oxidative stress, tumor necrosis factor-α, high glucose, lipopolysaccharide, and homocysteine possess cytotoxic effects in many tissues and induce apoptosis of ECs, and that sphingosine-1-phosphate protects ECs. Nevertheless, EC apoptosis in the context of those artificial microenvironments could be enhanced, reduced or even reversed along with the alteration of patterns of shear stress. An appropriate level of autophagy diminishes EC apoptosis to some extent, in addition to supporting cell survival upon microenvironment challenges. The intervention of pyroptosis showed a profound effect on atherosclerosis. Further cell and animal studies are required to ascertain whether the alterations in the levels of cell deaths and their associated regulatory mechanisms happen at local lesion sites with considerable mechanical force changes, for preventing senescence and cell deaths in the vascular-related diseases.

Mechano-regulated cell-cell signaling in the context of cardiovascular tissue engineering

Cardiovascular tissue engineering (CVTE) aims to create living tissues, with the ability to grow and remodel, as replacements for diseased blood vessels and heart valves. Despite promising results, the (long-term) functionality of these engineered tissues still needs improvement to reach broad clinical application. The functionality of native tissues is ensured by their specific mechanical properties directly arising from tissue organization. We therefore hypothesize that establishing a native-like tissue organization is vital to overcome the limitations of current CVTE approaches. To achieve this aim, a better understanding of the growth and remodeling (G&R) mechanisms of cardiovascular tissues is necessary. Cells are the main mediators of tissue G&R, and their behavior is strongly influenced by both mechanical stimuli and cell-cell signaling. An increasing number of signaling pathways has also been identified as mechanosensitive. As such, they may have a key underlying role in regulating the G&R of tissues in response to mechanical stimuli. A more detailed understanding of mechano-regulated cell-cell signaling may thus be crucial to advance CVTE, as it could inspire new methods to control tissue G&R and improve the organization and functionality of engineered tissues, thereby accelerating clinical translation. In this review, we discuss the organization and biomechanics of native cardiovascular tissues; recent CVTE studies emphasizing the obtained engineered tissue organization; and the interplay between mechanical stimuli, cell behavior, and cell-cell signaling. In addition, we review past contributions of computational models in understanding and predicting mechano-regulated tissue G&R and cell-cell signaling to highlight their potential role in future CVTE strategies.

Increased portal vein diameter is predictive of portal vein thrombosis development in patients with liver cirrhosis

Background

Cirrhotic patients with portal vein thrombosis (PVT) may have a high risk of hepatic decompensation and increased mortality. This study aimed to investigate if increased portal vein diameter is associated with PVT development.

Methods

A total of 174 cirrhotic patients were enrolled between February 1 and August 31, 2017. All participants were divided into PVT (n=62) and non-PVT (n=112) groups based on the thrombus that was detected by ultrasonography and confirmed by computed tomography angiography (CTA).

Results

The study participants, aged 54.7±10.5 years (PVT) and 55.8±11.6 years (non-PVT), were included in this analysis. The Child-Pugh score of PVT or non-PVT was 6.6±1.3 and 5.8±0.9, respectively. Hepatitis B virus (HBV) is the primary etiological agent of cirrhosis. Logistic regression, receiver operating characteristic (ROC), and nomograph analysis designated portal diameter as the strongest independent risk factor for predicting PVT development [odds ratio (OR): 3.96, area under the ROC curve (AUC): 0.88; P<0.01], and the cutoff with predictive value for PVT development was >12.5 mm. No differences were observed in the overall survival (OS) in cirrhosis with or without PVT or stratifying on portal diameter based on the cutoff value.

Conclusions

Increased portal diameter is associated with an increased risk of PVT development. Patients with cirrhosis and increased portal diameter are a high-risk subgroup that may need thromboprophylaxis.

Wenxin Granule Ameliorates Hypoxia/Reoxygenation-Induced Oxidative Stress in Mitochondria via the PKC-δ/NOX2/ROS Pathway in H9c2 Cells

Myocardial infarction and following reperfusion therapy-induced myocardial ischemia/reperfusion (I/R) injury have been recognized as an important subject of cardiovascular disease with high mortality. As the antiarrhythmic agent, Wenxin Granule (WXG) is widely used to arrhythmia and heart failure. In our pilot study, we found the antioxidative potential of WXG in the treatment of myocardial I/R. This study is aimed at investigating whether WXG could treat cardiomyocyte hypoxia/reoxygenation (H/R) injury by inhibiting oxidative stress in mitochondria. The H9c2 cardiomyocyte cell line was subject to H/R stimuli to mimic I/R injury in vitro. WXG was added to the culture medium 24 h before H/R exposing as pretreatment. Protein kinase C-δ (PKC-δ) inhibitor rottlerin or PKC-δ lentivirus vectors were conducted on H9c2 cells to downregulate or overexpress PKC-δ protein. Then, the cell viability, oxidative stress levels, intracellular and mitochondrial ROS levels, mitochondrial function, and apoptosis index were analyzed. In addition, PKC-δ protein expression in each group was verified by western blot analysis. Compared with the control group, the PKC-δ protein level was significantly increased in the H/R group, which was remarkably improved by WXG or rottlerin. PKC-δ lentivirus vector-mediated PKC-δ overexpression was not reduced by WXG. WXG significantly improved H/R-induced cell injury, lower levels of SOD and GSH/GSSG ratio, higher levels of MDA, intracellular and mitochondrial ROS content, mitochondrial membrane potential and ATP loss, mitochondrial permeability transition pore opening, NOX2 activation, cytochrome C release, Bax/Bcl-2 ratio and cleaved caspase-3 increasing, and cell apoptosis. Similar findings were obtained from rottlerin treatment. However, the protective effects of WXG were abolished by PKC-δ overexpression, indicating that PKC-δ was a potential target of WXG treatment. Our findings demonstrated a novel mechanism by which WXG attenuated oxidative stress and mitochondrial dysfunction of H9c2 cells induced by H/R stimulation via inhibitory regulation of PKC-δ/NOX2/ROS signaling.