Endothelial-to-mesenchymal transition: A novel therapeutic target for cardiovascular diseases

SARS-CoV-2-related peptides induce endothelial-to-mesenchymal transition in endothelial capillary cells derived from different body districts: focus on membrane (M) protein

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for the COVID-19, may lead to multiple organ dysfunctions and long-term complications. The induction of microvascular dysfunction is regarded as a main player in these pathological processes. To investigate the possible impact of SARS-CoV-2-induced endothelial-to-mesenchymal transition (EndMT) on fibrosis in "long-COVID" syndrome, we used primary cultures of human microvascular cells derived from the lungs, as the main infection target, compared to cells derived from different organs (dermis, heart, kidney, liver, brain) and to the HUVEC cell line. To mimic the virus action, we used mixed SARS-CoV-2 peptide fragments (PepTivator®) of spike (S), nucleocapsid (N), and membrane (M) proteins. TGFβ2 and cytokine mix (IL-1β, IL-6, TNFα) were used as positive controls. The percentage of cells positive to mesenchymal and endothelial markers was quantified by high content screening. We demonstrated that S+N+M mix induces irreversible EndMT in all analyzed endothelial cells via the TGFβ pathway, as demonstrated by ApoA1 treatment. We then tested the contribution of single peptides in lung and brain cells, demonstrating that EndMT is triggered by M peptide. This was confirmed by transfection experiment, inducing the endogenous expression of the glycoprotein M in lung-derived cells. In conclusion, we demonstrated that SARS-CoV-2 peptides induce EndMT in microvascular endothelial cells from multiple body districts. The different peptides play different roles in the induction and maintenance of the virus-mediated effects, which are organ-specific. These results corroborate the hypothesis of the SARS-CoV-2-mediated microvascular damage underlying the multiple organ dysfunctions and the long-COVID syndrome.

Inactivation of adenosine receptor 2A suppresses endothelial-to-mesenchymal transition and inhibits subretinal fibrosis in mice

Anti-vascular endothelial growth factor therapy has had a substantial impact on the treatment of choroidal neovascularization (CNV) in patients with neovascular age-related macular degeneration (nAMD), the leading cause of vision loss in older adults. Despite treatment, many patients with nAMD still develop severe and irreversible visual impairment because of the development of subretinal fibrosis. We recently reported the anti-inflammatory and antiangiogenic effects of inhibiting the gene encoding adenosine receptor 2A (Adora2a), which has been implicated in cardiovascular disease. Here, using two mouse models of subretinal fibrosis (mice with laser injury-induced CNV or mice with a deficiency in the very low-density lipoprotein receptor), we found that deletion of Adora2a either globally or specifically in endothelial cells reduced subretinal fibrosis independently of angiogenesis. We showed that Adora2a-dependent endothelial-to-mesenchymal transition contributed to the development of subretinal fibrosis in mice with laser injury-induced CNV. Deficiency of Adora2a in cultured mouse and human choroidal endothelial cells suppressed induction of the endothelial-to-mesenchymal transition. A metabolomics analysis of cultured human choroidal endothelial cells showed that ADORA2A knockdown with an siRNA reversed the increase in succinate because of decreased succinate dehydrogenase B expression under fibrotic conditions. Pharmacological inhibition of ADORA2A with a small-molecule KW6002 in both mouse models recapitulated the reduction in subretinal fibrosis observed in mice with genetic deletion of Adora2a. ADORA2A inhibition may be a therapeutic approach to treat subretinal fibrosis associated with nAMD.

Analysis of immunoinfiltration and EndoMT based on TGF-β signaling pathway-related genes in acute myocardial infarction

Acute myocardial infarction (AMI), a critical manifestation of coronary heart disease, presents a complex and not entirely understood etiology. This study investigates the potential role of immune infiltration and endothelial-mesenchymal transition (EndoMT) in AMI pathogenesis. We conducted an analysis of the GSE24519 and MSigDB datasets to identify differentially expressed genes associated with the TGF-β signaling pathway (DE-TSRGs) and carried out a functional enrichment analysis. Additionally, we evaluated immune infiltration in AMI and its possible link to myocardial fibrosis. Key genes were identified using machine learning and LASSO logistic regression. The expression of MEOX1 in the ventricular muscles and endothelial cells of Sprague-Dawley rats was assessed through RT-qPCR, immunohistochemical and immunofluorescence assays, and the effect of MEOX1 overexpression on EndoMT was investigated. Our study identified five DE-TSRGs, among which MEOX1, SMURF1, and SPTBN1 exhibited the most significant associations with AMI. Notably, we detected substantial immune infiltration in AMI specimens, with a marked increase in neutrophils and macrophages. MEOX1 demonstrated consistent expression patterns in rat ventricular muscle tissue and endothelial cells, and its overexpression induced EndoMT. Our findings suggest that the TGF-β signaling pathway may contribute to AMI progression by activating the immune response. MEOX1, linked to the TGF-β signaling pathway, appears to facilitate myocardial fibrosis via EndoMT following AMI. These novel insights into the mechanisms of AMI pathogenesis could offer promising therapeutic targets for intervention.

Overexpressed pigment epithelium-derived factor alleviates pulmonary hypertension in two rat models induced by monocrotaline and SU5416/hypoxia

BACKGROUND

Pulmonary hypertension (PH) is a progressive and fatal cardiopulmonary disease characterized by vascular remodeling and is associated with endothelial-to-mesenchymal transition (EndoMT). The pigment epithelium-derived factor (PEDF), a secretory protein widely distributed in multiple organs, has been shown to demonstrate anti-EndoMT activity in cardiovascular diseases. In the present study, the role of PEDF in PH was investigated.

METHODS

For PEDF overexpression, Sprague Dawley rats were infected with an adeno-associated virus through injection via the internal jugular vein. To establish PH models, the animals were subjected to monocrotaline or Sugen/hypoxia. Four weeks later, pulmonary artery angiography was performed, and hemodynamic parameters, right ventricular function, and vascular remodeling were evaluated. EndoMT and cell proliferation in the pulmonary arteries were assessed via immunofluorescence staining. Moreover, pulmonary artery endothelial cells (PAECs) isolated from experimental PH rats were cultured to investigate the underlying molecular mechanisms involved.

RESULTS

PEDF expression was significantly downregulated in PAECs from PH patients and PH model rats. Overexpressed PEDF alleviated the development of PH by improving pulmonary artery morphology and perfusion, reducing pulmonary artery pressure, improving right ventricular function, and alleviating vascular remodeling. PEDF inhibits EndoMT and reduces excessive PAEC proliferation. Moreover, PEDF overexpression reduced EndoMT in cultured PAECs by competitively inhibiting the binding of wnt to LRP6 and downregulating phosphorylation at the 1490 site of LRP6.

CONCLUSIONS

Our findings suggest that PEDF may be a potential therapeutic target for PH. We also found that PEDF can inhibit EndoMT in PAECs and may exert these effects by inhibiting the Wnt/LRP6/β-catenin pathway.

Increased expression of protein tyrosine phosphatase nonreceptor type 22 alters early T-cell receptor signaling and differentiation of CD4+ T cells in chronic heart failure

CD4+ T-cell counts are increased and activated in patients with chronic heart failure (CHF), whereas regulatory T-cell (Treg) expansion is inhibited, probably due to aberrant T-cell receptor (TCR) signaling. TCR signaling is affected by protein tyrosine phosphatase nonreceptor type 22 (PTPN22) in autoimmune disorders, but whether PTPN22 influences TCR signaling in CHF remains unclear. This observational case-control study included 45 patients with CHF [18 patients with ischemic heart failure versus 27 patients with nonischemic heart failure (NIHF)] and 16 non-CHF controls. We used flow cytometry to detect PTPN22 expression, tyrosine phosphorylation levels, zeta-chain-associated protein kinase, 70 kDa (ZAP-70) inhibitory residue tyrosine 292 and 319 phosphorylation levels, and CD4+ T cell and Treg proportions. We conducted lentivirus-mediated PTPN22 RNA silencing in isolated CD4+ T cells. PTPN22 expression increased in the CD4+ T cells of patients with CHF compared with that in controls. PTPN22 expression was positively correlated with left ventricular end-diastolic diameter and type B natriuretic peptide but negatively correlated with left ventricular ejection fraction in the NIHF group. ZAP-70 tyrosine 292 phosphorylation was decreased, which correlated positively with PTPN22 overexpression in patients with NIHF and promoted early TCR signaling. PTPN22 silencing induced Treg differentiation in CD4+ T cells from patients with CHF, which might account for the reduced frequency of peripheral Tregs in these patients. PTPN22 is a potent immunomodulator in CHF and might play an essential role in the development of CHF by promoting early TCR signaling and impairing Treg differentiation from CD4+ T cells.

Melatonin as a therapeutic agent for alleviating endothelial dysfunction in cardiovascular diseases: Emphasis on oxidative stress

The vascular endothelium is vital in maintaining cardiovascular health by regulating vascular permeability and tone, preventing thrombosis, and controlling vascular inflammation. However, when oxidative stress triggers endothelial dysfunction, it can lead to chronic cardiovascular diseases (CVDs). This happens due to oxidative stress-induced mitochondrial dysfunction, inflammatory responses, and reduced levels of nitric oxide. These factors cause damage to endothelial cells, leading to the acceleration of CVD progression. Melatonin, a natural antioxidant, has been shown to inhibit oxidative stress and stabilize endothelial function, providing cardiovascular protection. The clinical application of melatonin in the prevention and treatment of CVDs has received widespread attention. In this review, based on bibliometric studies, we first discussed the relationship between oxidative stress-induced endothelial dysfunction and CVDs, then summarized the role of melatonin in the treatment of atherosclerosis, hypertension, myocardial ischemia-reperfusion injury, and other CVDs. Finally, the potential clinical use of melatonin in the treatment of these diseases is discussed.

Endothelial ILK induces cardioprotection by preventing coronary microvascular dysfunction and endothelial-to-mesenchymal transition

Endothelial dysfunction is an early event in coronary microvascular disease. Integrin-linked kinase (ILK) prevents endothelial nitric oxide synthase (eNOS) uncoupling and, thus, endothelial dysfunction. However, the specific role of endothelial ILK in cardiac function remains to be fully elucidated. We hypothesised that endothelial ILK plays a crucial role in maintaining coronary microvascular function and contractile performance in the heart. We generated an endothelial cell-specific ILK conditional knock-out mouse (ecILK cKO) and investigated cardiovascular function. Coronary endothelial ILK deletion significantly impaired cardiac function: ejection fraction, fractional shortening and cardiac output decreased, whilst left ventricle diastolic internal diameter decreased and E/A and E/E' ratios increased, indicating not only systolic but also diastolic dysfunction. The functional data correlated with extensive extracellular matrix remodelling and perivascular fibrosis, indicative of adverse cardiac remodelling. Mice with endothelial ILK deletion suffered early ischaemic-like events with ST elevation and transient increases in cardiac troponins, which correlated with fibrotic remodelling. In addition, ecILK cKO mice exhibited many features of coronary microvascular disease: reduced cardiac perfusion, impaired coronary flow reserve and arterial remodelling with patent epicardial coronary arteries. Moreover, endothelial ILK deletion induced a moderate increase in blood pressure, but the antihypertensive drug Losartan did not affect microvascular remodelling whilst only partially ameliorated fibrotic remodelling. The plasma miRNA profile reveals endothelial-to-mesenchymal transition (endMT) as an upregulated pathway in endothelial ILK conditional KO mice. Our results show that endothelial cells in the microvasculature in endothelial ILK conditional KO mice underwent endMT. Moreover, endothelial cells isolated from these mice and ILK-silenced human microvascular endothelial cells underwent endMT, indicating that decreased endothelial ILK contributes directly to this endothelial phenotype shift. Our results identify ILK as a crucial regulator of microvascular endothelial homeostasis. Endothelial ILK prevents microvascular dysfunction and cardiac remodelling, contributing to the maintenance of the endothelial cell phenotype.

Endothelial-to-mesenchymal transition: New insights into vascular calcification

With the continuous progress of atherosclerosis research, the significant pathological change of it--vascular calcification (VC), gains increasing attention. In recent years, numerous studies have demonstrated that it is an independent predictor of death risk of cardiovascular disease, and it has a strong correlation with poor clinical prognosis. As the world's population continues to age, the occurrence of VC is expected to reach its highest point in the near future. Therefore, it is essential to investigate ways to prevent or even reverse this process for clinical purposes. Endothelial-to-mesenchymal transition (EndMT) describes the progressive differentiation of endothelial cells into mesenchymal stem cells (MSCs) under various stimuli and acquisition of pluripotent cell characteristics. More and more studies show that EndMT plays a vital role in various cardiovascular diseases, including atherosclerosis, vascular calcification and heart valvular disease. EndMT is also involved in the formation and progression of VC. This review vividly describes the history, characteristics of EndMT and how it affects the endothelial cell process, then focuses on the relationship between vascular endothelium, EndMT, amino acid metabolism, and vascular calcification. Finally, it overviews the signal pathway of EndMT and drugs targeting EndMT, hoping to provide new ideas and a theoretical basis for studying potential therapeutic targets of VC.

The Role of TGF-β Signaling in Saphenous Vein Graft Failure after Peripheral Arterial Disease Bypass Surgery

Saphenous vein bypass grafting is an effective technique used to treat peripheral arterial disease (PAD). However, restenosis is the major clinical challenge for the graft vessel among people with PAD postoperation. We hypothesize that there is a common culprit behind arterial occlusion and graft restenosis. To investigate this hypothesis, we found TGF-β, a gene specifically upregulated in PAD arteries, by bioinformatics analysis. TGF-β has a wide range of biological activities and plays an important role in vascular remodeling. We discuss the molecular pathway of TGF-β and elucidate its mechanism in vascular remodeling and intimal hyperplasia, including EMT, extracellular matrix deposition, and fibrosis, which are the important pathways contributing to stenosis. Additionally, we present a case report of a patient with graft restenosis linked to the TGF-β pathway. Finally, we discuss the potential applications of targeting the TGF-β pathway in the clinic to improve the long-term patency of vein grafts.

Injured Endothelial Cell: A Risk Factor for Pulmonary Fibrosis

The pathological features of pulmonary fibrosis (PF) are the abnormal activation and proliferation of myofibroblasts and the extraordinary deposition of the extracellular matrix (ECM). However, the pathogenesis of PF is still indistinct. In recent years, many researchers have realized that endothelial cells had a crucial role in the development of PF. Studies have demonstrated that about 16% of the fibroblasts in the lung tissue of fibrotic mice were derived from endothelial cells. Endothelial cells transdifferentiated into mesenchymal cells via the endothelial-mesenchymal transition (E(nd)MT), leading to the excessive proliferation of endothelial-derived mesenchymal cells and the accumulation of fibroblasts and ECM. This suggested that endothelial cells, a significant component of the vascular barrier, played an essential role in PF. Herein, this review discusses E(nd)MT and its contribution to the activation of other cells in PF, which could provide new ideas for further understanding the source and activation mechanism of fibroblasts and the pathogenesis of PF.

Oxidative stress and valvular endothelial cells in aortic valve calcification

Calcified aortic valve disease (CAVD) is a common cardiovascular disease in elderly individuals. Although it was previously considered a degenerative disease, it is, in fact, a progressive disease involving multiple mechanisms. Aortic valve endothelial cells, which cover the outermost layer of the aortic valve and are directly exposed to various pathogenic factors, play a significant role in the onset and progression of CAVD. Hemodynamic changes can directly damage the structure and function of valvular endothelial cells (VECs). This leads to inflammatory infiltration and oxidative stress, which promote the progression of CAVD. VECs can regulate the pathological differentiation of valvular interstitial cells (VICs) through NO and thus affect the process of CAVD. Under the influence of pathological factors, VECs can also be transformed into VICs through EndMT, and then the pathological differentiation of VICs eventually leads to the formation of calcification. This review discusses the role of VECs, especially the role of oxidative stress in VECs, in the process of aortic valve calcification.

LncRNA DANCR deficiency promotes high glucose-induced endothelial to mesenchymal transition in cardiac microvascular cells via the FoxO1/DDAH1/ADMA signaling pathway

Cardiac fibrosis is the main pathological basis of diabetic cardiomyopathy (DCM), and endothelial-to-meschenymal transition (EndMT) is a key driver to cardiac fibrosis and plays an important role in the pathogenesis of DCM. Asymmetric dimethylarginine (ADMA), a crucial pathologic factor in diabetes mellitus, is involved in organ fibrosis. This study aims to evaluate underlying mechanisms of ADMA in DCM especially for EndMT under diabetic conditions. A diabetic rat model was induced by streptozotocin (STZ) injection, and human cardiac microvascular endothelial cells (HCMECs) were stimulated with high glucose to induce EndMT. Subsequently, the role of ADMA in EndMT was detected either by exogenous ADMA or by over-expressing dimethylarginine dimethylaminohydrolase 1 (DDAH1, degradation enzyme for ADMA) before high glucose stimulation. Furthermore, the relationships among forkhead box protein O1 (FoxO1), DDAH1 and ADMA were evaluated by FoxO1 over-expression or FoxO1 siRNA. Finally, we examined the roles of LncRNA DANCR in FoxO1/DDAH1/ADMA pathway and EndMT of HCMECs. Here, we found that EndMT in HCMECs was induced by high glucose, as evidenced by down-regulated expression of CD31 and up-regulated expression of FSP-1 and collagen Ⅰ. Importantly, ADMA induced EndMT in HCMECs, and over-expressing DDAH1 protected from developing EndMT by high glucose. Furthermore, we demonstrated that over-expression of FoxO1-ADA with mutant phosphorylation sites of T24A, S256D, and S316A induced EndMT of HCMECs by down-regulating of DDAH1 and elevating ADMA, and that EndMT of HCMECs induced by high glucose was reversed by FoxO1 siRNA. We also found that LncRNA DANCR siRNA induced EndMT of HCMECs, activated FoxO1, and inhibited DDAH1 expression. Moreover, over-expression of LncRNA DANCR could markedly attenuated high glucose-mediated EndMT of HCMECs by inhibiting the activation of FoxO1 and increasing the expression of DDAH1. Collectively, our results indicate that LncRNA DANCR deficiency promotes high glucose-induced EndMT in HCMECs by regulating FoxO1/DDAH1/ADMA pathway.

High glucose levels contribute to vascular fibrosis via the activation of the endothelial-to-mesenchymal transition in periodontitis

OBJECTIVE

To determine the changes of Porphyromonas gingivalis (P. gingivalis) growth and metabolism and identify whether the vascular epithelium change could be induced in diabetic periodontitis.

BACKGROUND

Maintaining favourable vascular function is a precondition for periodontal regeneration. In diabetic periodontitis, high glucose levels could enhance the metabolism of pathogens, and a complex condition involving inflammation and high glucose levels would disrupt homeostasis of the epithelium and promote fibrosis by endothelial-to-mesenchymal transition (EndMT).

METHODS

Porphyromonas gingivalis was cultured with glucose to judge its metabolic activity. Human umbilical vein endothelial cells (HUVECs) were treated with P. gingivalis-lipopolysaccharide (LPS) (10 μg/ml) and/or high glucose concentrations (25 mM), and transforming growth factor (TGF)-β inhibitor was used to block EndMT. Inflammation level was assessed by flow cytometry. Multiple biological functions including EndMT, angiopoiesis, and cell migration were analysed. Additionally, gene expressions and protein levels were determined with qPCR and western blot, respectively. Finally, blood vessels were cultured ex vivo, and EndMT and fibrosis markers were detected by immunohistochemistry.

RESULTS

Glucose could promote P. gingivalis growth and biofilm formation as well as the expression of virulence factor genes including FimA, RgpA, RgpB, and Kgp. P. gingivalis-LPS and glucose could increase intracellular reactive oxygen species (ROS) and promote fibrosis via EndMT in HUVECs, along with attenuating angiopoiesis and cell migration, which could be resumed by blocking EndMT with TGF-β inhibitor. Vascular fibrosis was observed after the addition of glucose via EndMT regulation.

CONCLUSION

Glucose augmented the growth and metabolism of P. gingivalis and promoted fibrosis by the activation of EndMT, as well as the inhibition of angiopoiesis and cell migration.

The Interaction of Apelin and FGFR1 Ameliorated the Kidney Fibrosis through Suppression of TGFβ-Induced Endothelial-to-Mesenchymal Transition

Both epithelial-to-mesenchymal (EMT) and endothelial-to-mesenchymal (EndMT) transitions have shown to contribute to the development and progression of kidney fibrosis. It has been reported that apelin, a regulatory peptide, alleviates EMT by inhibiting the transforming growth factor β (TGFβ) pathway in renal diseases. Additionally, fibroblast growth factor receptor 1 (FGFR1) has been shown to be a key inhibitor of EndMT through suppression of the TGFβ/Smad pathway. In this study, we found that apelin and FGFR1 were spatially close to each other and that the apelin and FGFR1 complex displayed inhibitory effects on TGFβ/Smad signaling as well as associated EndMT in diabetic kidney fibrosis. In cultured human dermal microvascular endothelial cells (HMVECs), we found that the anti-EndMT and anti-TGFβ/Smad effects of apelin were dampened in FGFR1-deficient cells. Either siRNA- or an inhibitor-mediated deficiency of apelin induced the Smad3 phosphorylation and EndMT. Streptozotocin-induced CD-1 diabetic mice displayed EndMT and associated kidney fibrosis, which were restored by apelin treatment. The medium from apelin-deficient endothelial cells stimulated TGFβ/Smad-dependent EMT in cultured HK2 cells. In addition, depletion of apelin and the FGFR1 complex impaired CEBPA expression, and TGFβ-induced repression of CEBPA expression contributed to the initiation of EndMT in the endothelium. Collectively, these findings revealed that the interaction between apelin and FGFR1 displayed renoprotective potential through suppression of the TGFβ/Smad/CEBPA-mediated EndMT/EMT pathways.

Exosomal miR-3131 derived from endothelial cells with KRAS mutation promotes EndMT by targeting PICK1 in brain arteriovenous malformations

AIMS

To explore the underlying mechanism by which low-frequency KRAS mutations result in extensive EndMT occurrence.

METHODS

Exosomes derived from primarily cultured brain arteriovenous malformation (bAVMs) and human umbilical vein endothelial cells (HUVECs) transfected with KRAS^G12D , KRAS^WT , or KRAS^NC lentiviruses were isolated, and their effects on HUVECs were identified by western blotting and immunofluorescence staining. The expression levels of exosomal microRNAs (miRNAs) were evaluated by miRNA microarray, followed by functional experiments on miR-3131 and detection of its downstream target, and miR-3131 inhibitor in reversing the EndMT process induced by KRAS^G12D -transfected HUVECs and bAVM endothelial cells (ECs) were explored.

RESULTS

Exosomes derived from KRAS^G12D bAVM ECs and KRAS^G12D -transfected HUVECs promoted EndMT in HUVECs. MiR-3131 levels were highest in the exosomes of KRAS^G12D -transfected HUVECs, and HUVECs transfected with the miR-3131 mimic acquired mesenchymal phenotypes. RNA-seq and dual-luciferase reporter assays revealed that PICK1 is the direct downstream target of miR-3131. Exosomal miR-3131 was highly expressed in KRAS^G12D bAVM^exos compared with non-KRAS-mutant bAVM^exos or HUVEC^exos . Finally, a miR-3131 inhibitor reversed EndMT in HUVECs treated with exosomes or the supernatant of KRAS^G12D -transfected HUVECs and KRAS^G12D bAVM ECs.

CONCLUSION

Exosomal miR-3131 promotes EndMT in KRAS-mutant bAVMs, and miR-3131 might be a potential biomarker and therapeutic target in KRAS^G12D -mutant bAVMs.

Hydrogen Sulfide Modulates Endothelial-Mesenchymal Transition in Heart Failure

BACKGROUND

Hydrogen sulfide is a critical endogenous signaling molecule that exerts protective effects in the setting of heart failure. Cystathionine γ-lyase (CSE), 1 of 3 hydrogen-sulfide-producing enzyme, is predominantly localized in the vascular endothelium. The interaction between the endothelial CSE-hydrogen sulfide axis and endothelial-mesenchymal transition, an important pathological process contributing to the formation of fibrosis, has yet to be investigated.

METHODS

Endothelial-cell-specific CSE knockout and Endothelial cell-CSE overexpressing mice were subjected to transverse aortic constriction to induce heart failure with reduced ejection fraction. Cardiac function, vascular reactivity, and treadmill exercise capacity were measured to determine the severity of heart failure. Histological and gene expression analyses were performed to investigate changes in cardiac fibrosis and the activation of endothelial-mesenchymal transition.

RESULTS

Endothelial-cell-specific CSE knockout mice exhibited increased endothelial-mesenchymal transition and reduced nitric oxide bioavailability in the myocardium, which was associated with increased cardiac fibrosis, impaired cardiac and vascular function, and worsened exercise performance. In contrast, genetic overexpression of CSE in endothelial cells led to increased myocardial nitric oxide, decreased endothelial-mesenchymal transition and cardiac fibrosis, preserved cardiac and endothelial function, and improved exercise capacity.

CONCLUSIONS

Our data demonstrate that endothelial CSE modulates endothelial-mesenchymal transition and ameliorate the severity of pressure-overload-induced heart failure, in part, through nitric oxide-related mechanisms. These data further suggest that endothelium-derived hydrogen sulfide is a potential therapeutic for the treatment of heart failure with reduced ejection fraction.

ZPI prevents ox-LDL-mediated endothelial injury leading to inhibition of EndMT, inflammation, apoptosis, and oxidative stress through activating Pi3k/Akt signal pathway

Oxidized low-density lipoprotein (ox-LDL)-mediated endothelial dysfunction exerts an essential role in the development of atherosclerosis. Protein Z-dependent protease inhibitor (ZPI), a member of the serine protease inhibitor superfamily, could inhibit the function of activated coagulation factor X (FXa) via interaction with protein Z (PZ). Studies have pointed out that ZPI was statistically related to atherosclerotic diseases, which may have a robust cardiovascular protective effect. However, the underlying mechanism of ZPI on ox-LDL-mediated endothelial injury requires further elucidation. Human umbilical vein endothelial cells (HUVECs) were treated with ox-LDL (100 μg/ml) and ZPI (10 μg/ml). Cell viability was measured by the Cell Counting Kit-8 (CCK-8) assay. Cell apoptosis, oxidative stress, and endothelial-to-mesenchymal transition (EndMT) were analyzed by immunofluorescence (IF). Cell migration was measured using a wound-healing assay. Quantitative real-time polymerase chain reaction and western blot analysis were performed to determine messenger RNA and protein expression. Ox-LDL (100 μg/ml, 48 h) significantly reduced cell viability and migration, increased EndMT, inflammation, apoptosis, and oxidative stress. The related protein expression of phosphatidylinositol 3 kinase/protein kinase B (Pi3k/Akt) signal pathway in HUVECs was also simultaneously decreased. We also discovered that ZPI treatment could prevent ox-LDL-mediated endothelial injury through the improvement of cell viability and alleviation of apoptosis, oxidative stress, EndMT, and inflammation. Thus, the protective effect of ZPI on HUVECs may be mediated by activation of the Pi3k/Akt signal pathway. ZPI may exert an important protective role in HUVECs dysfunction triggered by ox-LDL via activation of the Pi3k/Akt signal pathway. Therefore, ZPI may possess potential therapeutic effects on atherosclerotic endothelial injury-related diseases.

Endothelial Dysfunction in the Context of Blood–Brain Barrier Modeling

Here, we discuss pathophysiological approaches to the defining of endothelial dysfunction criteria (i.e., endothelial activation, impaired endothelial mechanotransduction, endothelial-to-mesenchymal transition, reduced nitric oxide release, compromised endothelial integrity, and loss of anti-thrombogenic properties) in different in vitro and in vivo models. The canonical definition of endothelial dysfunction includes insufficient production of vasodilators, pro-thrombotic and pro-inflammatory activation of endothelial cells, and pathologically increased endothelial permeability. Among the clinical consequences of endothelial dysfunction are arterial hypertension, macro- and microangiopathy, and microalbuminuria. We propose to extend the definition of endothelial dysfunction by adding altered endothelial mechanotransduction and endothelial-to-mesenchymal transition to its criteria. Albeit interleukin-6, interleukin-8, and MCP-1/CCL2 dictate the pathogenic paracrine effects of dysfunctional endothelial cells and are therefore reliable endothelial dysfunction biomarkers in vitro, they are non-specific for endothelial cells and cannot be used for the diagnostics of endothelial dysfunction in vivo. Conceptual improvements in the existing methods to model endothelial dysfunction, specifically, in relation to the blood–brain barrier, include endothelial cell culturing under pulsatile flow, collagen IV coating of flow chambers, and endothelial lysate collection from the blood vessels of laboratory animals in situ for the subsequent gene and protein expression profiling. Combined with the simulation of paracrine effects by using conditioned medium from dysfunctional endothelial cells, these flow-sensitive models have a high physiological relevance, bringing the experimental conditions to the physiological scenario.

Endothelial Cell Phenotype, a Major Determinant of Venous Thrombo-Inflammation

Reduced blood flow velocity in the vein triggers inflammation and is associated with the release into the extracellular space of alarmins or damage-associated molecular patterns (DAMPs). These molecules include extracellular nucleic acids, extracellular purinergic nucleotides (ATP, ADP), cytokines and extracellular HMGB1. They are recognized as a danger signal by immune cells, platelets and endothelial cells. Hence, endothelial cells are capable of sensing environmental cues through a wide variety of receptors expressed at the plasma membrane. The endothelium is then responding by expressing pro-coagulant proteins, including tissue factor, and inflammatory molecules such as cytokines and chemokines involved in the recruitment and activation of platelets and leukocytes. This ultimately leads to thrombosis, which is an active pro-inflammatory process, tightly regulated, that needs to be properly resolved to avoid further vascular damages. These mechanisms are often dysregulated, which promote fibrinolysis defects, activation of the immune system and irreversible vascular damages further contributing to thrombotic and inflammatory processes. The concept of thrombo-inflammation is now widely used to describe the complex interactions between the coagulation and inflammation in various cardiovascular diseases. In endothelial cells, activating signals converge to multiple intracellular pathways leading to phenotypical changes turning them into inflammatory-like cells. Accumulating evidence suggest that endothelial to mesenchymal transition (EndMT) may be a major mechanism of endothelial dysfunction induced during inflammation and thrombosis. EndMT is a biological process where endothelial cells lose their endothelial characteristics and acquire mesenchymal markers and functions. Endothelial dysfunction might play a central role in orchestrating and amplifying thrombo-inflammation thought induction of EndMT processes. Mechanisms regulating endothelial dysfunction have been only partially uncovered in the context of thrombotic diseases. In the present review, we focus on the importance of the endothelial phenotype and discuss how endothelial plasticity may regulate the interplay between thrombosis and inflammation. We discuss how the endothelial cells are sensing and responding to environmental cues and contribute to thrombo-inflammation with a particular focus on venous thromboembolism (VTE). A better understanding of the precise mechanisms involved and the specific role of endothelial cells is needed to characterize VTE incidence and address the risk of recurrent VTE and its sequelae.

Targeting Oxidative Stress and Endothelial Dysfunction Using Tanshinone IIA for the Treatment of Tissue Inflammation and Fibrosis

Salvia miltiorrhiza Burge (Danshen), a member of the Lamiaceae family, has been used in traditional Chinese medicine for many centuries as a valuable medicinal herb with antioxidative, anti-inflammatory, and antifibrotic potential. Several evidence-based reports have suggested that Salvia miltiorrhiza and its components prevent vascular diseases, including myocardial infarction, myocardial ischemia/reperfusion injury, arrhythmia, cardiac hypertrophy, and cardiac fibrosis. Tanshinone IIA (TanIIA), a lipophilic component of Salvia miltiorrhiza, has gained attention because of its possible preventive and curative activity against cardiovascular disorders. TanIIA, which possesses antioxidative, anti-inflammatory, and antifibrotic properties, could be a key component in the therapeutic potential of Salvia miltiorrhiza. Vascular diseases are often initiated by endothelial dysfunction, which is accompanied by vascular inflammation and fibrosis. In this review, we summarize how TanIIA suppresses tissue inflammation and fibrosis through signaling pathways such as PI3K/Akt/mTOR/eNOS, TGF-β1/Smad2/3, NF-κB, JNK/SAPK (stress-activated protein kinase)/MAPK, and ERK/Nrf2 pathways. In brief, this review illustrates the therapeutic value of TanIIA in the alleviation of oxidative stress, inflammation, and fibrosis, which are critical components of cardiovascular disorders.

Bioactivities and mechanisms of natural medicines in the management of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive and rare disease without obvious clinical symptoms that shares characteristics with pulmonary vascular remodeling. Right heart failure in the terminal phase of PAH seriously threatens the lives of patients. This review attempts to comprehensively outline the current state of knowledge on PAH its pathology, pathogenesis, natural medicines therapy, mechanisms and clinical studies to provide potential treatment strategies. Although PAH and pulmonary hypertension have similar pathological features, PAH exhibits significantly elevated pulmonary vascular resistance caused by vascular stenosis and occlusion. Currently, the pathogenesis of PAH is thought to involve multiple factors, primarily including genetic/epigenetic factors, vascular cellular dysregulation, metabolic dysfunction, even inflammation and immunization. Yet many issues regarding PAH need to be clarified, such as the "oestrogen paradox". About 25 kinds monomers derived from natural medicine have been verified to protect against to PAH via modulating BMPR2/Smad, HIF-1α, PI3K/Akt/mTOR and eNOS/NO/cGMP signalling pathways. Yet limited and single PAH animal models may not corroborate the efficacy of natural medicines, and those natural compounds how to regulate crucial genes, proteins and even microRNA and lncRNA still need to put great attention. Additionally, pharmacokinetic studies and safety evaluation of natural medicines for the treatment of PAH should be undertaken in future studies. Meanwhile, methods for validating the efficacy of natural drugs in multiple PAH animal models and precise clinical design are also urgently needed to promote advances in PAH.

Shinjulactone A Blocks Vascular Inflammation and the Endothelial-Mesenchymal Transition

Objective

Methods

Results

Conclusion

Aspirin ameliorates pulmonary vascular remodeling in pulmonary hypertension by dampening endothelial-to-mesenchymal transition

Pulmonary vascular remodeling (PVR) is the pathological basis of pulmonary hypertension (PH). Incomplete understanding of PVR etiology has hindered drug development for this devastating disease, which exhibits poor prognosis despite the currently available therapies. Endothelial-to-mesenchymal transition (EndMT), a process of cell transdifferentiation, has been recently implicated in cardiovascular diseases, including PH. But the questions of how EndMT occurs and how to pharmacologically target EndMT in vivo have yet to be further answered. Herein, by performing hematoxylin-eosin and immunofluorescence staining, transmission electron microscopy and Western blotting, we found that EndMT plays a key role in the pathogenesis of PH, and importantly that aspirin, a FDA-approved widely used drug, was capable of ameliorating PVR in a preclinical rat model of hypoxia-induced PH. Moreover, aspirin exerted its inhibitory effects on EndMT in vitro and in vivo by suppressing HIF-1α/TGF-β1/Smads/Snail signaling pathway. Our data suggest that EndMT represents an intriguing drug target for the prevention and treatment of hypoxic PH and that aspirin may be repurposed to meet the urgent therapeutic needs of hypoxic PH patients.

Resident vascular endothelial progenitor definition and function: the age of reckoning

The cardiovascular system is composed around the central function of the endothelium that lines the inner surfaces of its vessels. In recent years, the existence of a progenitor population within the endothelium has been validated through the study of endothelial colony-forming cells (ECFCs) in human peripheral blood and certain vascular beds. However, our knowledge on endothelial populations in vivo that can give rise to ECFCs in culture has been limited. In this review we report and analyse recent attempts at describing progenitor populations in vivo from murine studies that reflect the self-renewal and stemness capacity observed in ECFCs. We pinpoint seminal discoveries within the field, which have phenotypically defined, and functionally scrutinised these endothelial progenitors. Furthermore, we review recent publications utilising single-cell sequencing technologies to better understand the endothelium in homeostasis and pathology.

Self-eating and Heart: The Emerging Roles of Autophagy in Calcific Aortic Valve Disease

Autophagy is a self-degradative pathway by which subcellular elements are broken down intracellularly to maintain cellular homeostasis. Cardiac autophagy commonly decreases with aging and is accompanied by the accumulation of misfolded proteins and dysfunctional organelles, which are undesirable to the cell. Reduction of autophagy over time leads to aging-related cardiac dysfunction and is inversely related to longevity. However, despite the increasing interest in autophagy in cardiac diseases and aging, the process remains an undervalued and disregarded object in calcific valvular disease. Neither the nature through which autophagy is triggered nor the interplay between autophagic machinery and targeted molecules during aortic valve calcification are fully understood. Recently, the upregulation of autophagy has been shown to result in cardioprotective effects against cell death as well as its origin. Here, we review the evidence that shows how autophagy can be both beneficial and detrimental as it pertains to aortic valve calcification in the heart.

HDAC3 inhibitor suppresses endothelial-to-mesenchymal transition via modulating inflammatory response in atherosclerosis

A total number of 18 different isoforms of histone deacetylases (HDACs) which were categorized into 4 classes have been identified in human. HDAC3 is categorized as class I HDACs and is closely related to the occurrence and development of atherosclerosis. Recent evidence has pointed to endothelial-to-mesenchymal transition (EndMT) as a key process in vascular inflammation in atherosclerosis. However, little is known about the effect of HDAC3 on EndMT in atherosclerosis. Therefore, we aimed to investigate the effect of HDAC3 specific inhibitor on EndMT in ApoE^-/- mice fed a Western diet and human umbilical vein endothelial cells (HUVECs) induced by inflammatory cytokines. Firstly, we found that HDAC3 expression was up-regulated and EndMT occurred in the aortas of ApoE^-/- mice compared with C57BL/6J mice. However, HDAC3 specific inhibitor RGFP966 alleviated atherosclerotic lesions and inhibited EndMT of the atherosclerotic plaque in ApoE^-/- mice. Then, in vitro study showed that inflammatory cytokines TNF-α and IL-1β co-treatment increased the expression of HDAC3 and induced EndMT in HUVECs. HDAC3 inhibition by siRNA or specific inhibitor RGFP966 suppressed EndMT in HUVECs stimulated with TNF-α and IL-1β. By contrast, HDAC3 overexpression by adenovirus further promoted EndMT of HUVECs. In addition, we found that HDAC3 also regulated the inflammatory response of HUVECs by modulating the expression of inflammatory cytokines and the number of monocytes attached to HUVECs. These above results suggest that HDAC3 inhibitor suppresses EndMT via modulating inflammatory response in ApoE^-/- mice and HUVECs.

Modulation of EndMT by Hydrogen Sulfide in the Prevention of Cardiovascular Fibrosis

Endothelial mesenchymal transition (EndMT) has been described as a fundamental process during embryogenesis; however, it can occur also in adult age, underlying pathological events, including fibrosis. Indeed, during EndMT, the endothelial cells lose their specific markers, such as vascular endothelial cadherin (VE-cadherin), and acquire a mesenchymal phenotype, expressing specific products, such as α-smooth muscle actin (α-SMA) and type I collagen; moreover, the integrity of the endothelium is disrupted, and cells show a migratory, invasive and proliferative phenotype. Several stimuli can trigger this transition, but transforming growth factor (TGF-β1) is considered the most relevant. EndMT can proceed in a canonical smad-dependent or non-canonical smad-independent manner and ultimately regulate gene expression of pro-fibrotic machinery. These events lead to endothelial dysfunction and atherosclerosis at the vascular level as well as myocardial hypertrophy and fibrosis. Indeed, EndMT is the mechanism which promotes the progression of cardiovascular disorders following hypertension, diabetes, heart failure and also ageing. In this scenario, hydrogen sulfide (H₂S) has been widely described for its preventive properties, but its role in EndMT is poorly investigated. This review is focused on the evaluation of the putative role of H₂S in the EndMT process.

miRNA-200c-3p promotes endothelial to mesenchymal transition and neointimal hyperplasia in artery bypass grafts

Increasing evidence has suggested a critical role for endothelial‐to‐mesenchymal transition (EndoMT) in a variety of pathological conditions. MicroRNA‐200c‐3p (miR‐200c‐3p) has been implicated in epithelial‐to‐mesenchymal transition. However, the functional role of miR‐200c‐3p in EndoMT and neointimal hyperplasia in artery bypass grafts remains largely unknown. Here we demonstrated a critical role for miR‐200c‐3p in EndoMT. Proteomics and luciferase activity assays revealed that fermitin family member 2 (FERM2) is the functional target of miR‐200c‐3p during EndoMT. FERMT2 gene inactivation recapitulates the effect of miR‐200c‐3p overexpression on EndoMT, and the inhibitory effect of miR‐200c‐3p inhibition on EndoMT was reversed by FERMT2 knockdown. Further mechanistic studies revealed that FERM2 suppresses smooth muscle gene expression by preventing serum response factor nuclear translocation and preventing endothelial mRNA decay by interacting with Y‐box binding protein 1. In a model of aortic grafting using endothelial lineage tracing, we observed that miR‐200c‐3p expression was dramatically up‐regulated, and that EndoMT contributed to neointimal hyperplasia in grafted arteries. MiR‐200c‐3p inhibition in grafted arteries significantly up‐regulated FERM2 gene expression, thereby preventing EndoMT and reducing neointimal formation. Importantly, we found a high level of EndoMT in human femoral arteries with atherosclerotic lesions, and that miR‐200c‐3p expression was significantly increased, while FERMT2 expression levels were dramatically decreased in diseased human arteries. Collectively, we have documented an unexpected role for miR‐200c‐3p in EndoMT and neointimal hyperplasia in grafted arteries. Our findings offer a novel therapeutic opportunity for treating vascular diseases by specifically targeting the miR‐200c‐3p/FERM2 regulatory axis. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Puerarin attenuates the endothelial-mesenchymal transition induced by oxidative stress in human coronary artery endothelial cells through PI3K/AKT pathway

Endothelial-mesenchymal transition (EndMT) is a process in which endothelial cells lose their specific morphology/markers and undergo a dramatic remodeling of the cytoskeleton. It has been implicated in the progression of cardiovascular diseases such as cardiac fibrosis and cardiac dysfunction. Recent study indicated that puerarin could inhibit EndMT against cardiac fibrosis. However, the precise role of puerarin in EndMT and the underlying molecular mechanisms remain unclear. EndMT was induced by H₂O₂ (150 μM) in human coronary artery endothelial cells (HCAECs). HCAECs were exposed to H₂O₂ for six days with or without puerarin pretreated 2 h. The protein changes of EndMT markers (CD31, VE-cadherin, FSP1 and α-SMA) in HCAECs were detected. The levels of phosphoinositide-3-kinase (PI3K) and protein kinase B (AKT) proteins were analyzed by Western Blot. Wound healing and transwell assay were carried out to examine cell chemotaxis. Puerarin mitigated H₂O₂-induced EndMT as indicated by alleviating the reduced expression of CD31 and VE-cadherin and inhibiting the upregulation of α-SMA and FSP1. Furthermore, the mechanisms study showed that puerarin activated the PI3K/AKT pathway by inhibiting reactive oxygen species and further attenuated EndMT. On the other hand, PI3K inhibitor LY294002 reversed this effect imposed by puerarin. Puerarin alleviated the migration of mesenchymal-like cells through reducing MMPs protein expression. These results implicated that puerarin exhibited cytoprotective effects against H₂O₂-induced EndMT in HCAECs through alleviating oxidative stress, activating the PI3K/AKT pathway and limiting cell migration.

Mechanisms of the Osteogenic Switch of Smooth Muscle Cells in Vascular Calcification: WNT Signaling, BMPs, Mechanotransduction, and EndMT

Characterized by the hardening of arteries, vascular calcification is the deposition of hydroxyapatite crystals in the arterial tissue. Calcification is now understood to be a cell-regulated process involving the phenotypic transition of vascular smooth muscle cells into osteoblast-like cells. There are various pathways of initiation and mechanisms behind vascular calcification, but this literature review highlights the wingless-related integration site (WNT) pathway, along with bone morphogenic proteins (BMPs) and mechanical strain. The process mirrors that of bone formation and remodeling, as an increase in mechanical stress causes osteogenesis. Observing the similarities between the two may aid in the development of a deeper understanding of calcification. Both are thought to be regulated by the WNT signaling cascade and bone morphogenetic protein signaling and can also be activated in response to stress. In a pro-calcific environment, integrins and cadherins of vascular smooth muscle cells respond to a mechanical stimulus, activating cellular signaling pathways, ultimately resulting in gene regulation that promotes calcification of the vascular extracellular matrix (ECM). The endothelium is also thought to contribute to vascular calcification via endothelial to mesenchymal transition, creating greater cell plasticity. Each of these factors contributes to calcification, leading to increased cardiovascular mortality in patients, especially those suffering from other conditions, such as diabetes and kidney failure. Developing a better understanding of the mechanisms behind calcification may lead to the development of a potential treatment in the future.

Circulating miRNAs as molecular markers of occupational grain dust exposure

Dust from grain and feed production may cause adverse health effects in exposed workers. In this study we explored circulating miRNAs as potential biomarkers of occupational grain dust exposure. Twenty-two serum miRNAs were analyzed in 44 grain dust exposed workers and 22 controls. Exposed workers had significantly upregulated miR-18a-5p, miR-124-3p and miR-574-3p, and downregulated miR-19b-3p and miR-146a-5p, compared to controls. Putative target genes for the differentially expressed miRNAs were involved in a range of Kyoto Encyclopedia of Genes and Genomes signaling pathways, and ‘Pathways in cancer’ and ‘Wnt signaling pathway’ were common for all the five miRNAs. MiRNA-diseases association analysis showed a link between the five identified miRNAs and several lung diseases terms. A positive correlation between miR-124-3p, miR-18a-5p, and miR-574-3p and IL-6 protein level was shown, while miR-19b-3p was inversely correlated with CC-16 and sCD40L protein levels. Receiver-operating characteristic analysis of the five miRNA showed that three miRNAs (miR-574-3p, miR-124-3p and miR-18a-5p) could distinguish the grain dust exposed group from the control group, with miR-574-3p as the strongest predictor of grain dust exposure. In conclusion, this study identified five signature miRNAs as potential novel biomarkers of grain dust exposure that may have potential as early disease markers.

Non-coding RNA in endothelial-to-mesenchymal transition

Endothelial-to-mesenchymal transition (EndMT) is the process wherein endothelial cells lose their typical endothelial cell markers and functions and adopt a mesenchymal-like phenotype. EndMT is required for development of the cardiac valves, the pulmonary and dorsal aorta, and arterial maturation, but activation of the EndMT programme during adulthood is believed to contribute to several pathologies including organ fibrosis, cardiovascular disease, and cancer. Non-coding RNAs, including microRNAs, long non-coding RNAs, and circular RNAs, modulate EndMT during development and disease. Here, we review the mechanisms by which non-coding RNAs facilitate or inhibit EndMT during development and disease and provide a perspective on the therapeutic application of non-coding RNAs to treat fibroproliferative cardiovascular disease.

Identification of atheroprone shear stress responsive regulatory elements in endothelial cells

AIMS

Oscillatory shear stress (OSS) is an atheroprone haemodynamic force that occurs in areas of vessel irregularities and is implicated in the pathogenesis of atherosclerosis. Changes in signalling and transcriptional programme in response to OSS have been vigorously studied; however, the underlying changes in the chromatin landscape controlling transcription remain to be elucidated. Here, we investigated the changes in the regulatory element (RE) landscape of endothelial cells under atheroprone OSS conditions in an in vitro model.

METHODS AND RESULTS

Analyses of H3K27ac chromatin immunoprecipitation-Seq enrichment and RNA-Seq in primary human umbilical vein endothelial cells 6 h after onset of OSS identified 2806 differential responsive REs and 33 differentially expressed genes compared with control cells kept under static conditions. Furthermore, gene ontology analyses of putative RE-associated genes uncovered enrichment of WNT/HIPPO pathway and cytoskeleton reorganization signatures. Transcription factor (TF) binding motif analysis within RE sequences identified over-representation of ETS, Zinc finger, and activator protein 1 TF families that regulate cell cycle, proliferation, and apoptosis, implicating them in the development of atherosclerosis. Importantly, we confirmed the activation of EGR1 as well as the YAP/TAZ complex early (6 h) after onset of OSS in both cultured human vein and artery endothelial cells and, by undertaking luciferase assays, functionally verified their role in RE activation in response to OSS.

CONCLUSIONS

Based on the identification and verification of specific responsive REs early upon OSS exposure, we propose an expanded mechanism of how OSS might contribute to the development of atherosclerosis.

miR-448-3p alleviates diabetic vascular dysfunction by inhibiting endothelial-mesenchymal transition through DPP-4 dysregulation

Diabetes mellitus (DM) often causes vascular endothelial damage and alters vascular microRNA (miR) expression. miR-448-3p has been reported to be involved in the development of DM, but whether miR-448-3p regulates diabetic vascular endothelial dysfunction remains unclear. To investigate the molecular mechanism of diabetic vascular endothelial dysfunction and the role of miR-448-3p therein, Sprague-Dawley rats were injected with streptozotocin (STZ) to establish diabetic animal model and the rat aortic endothelial cells were treated with high glucose to establish diabetic cell model. For the treatment group, after the induction of diabetes, the miR-448-3p levels in vivo and in vitro were upregulated by adeno-associated virus serotype 2 (AAV2)-miR-448-3p injection and miR-448-3p mimic transfection, respectively. Our results showed that AAV2-miR-448-3p injection alleviated the body weight loss and blood glucose level elevation induced by STZ injection. The miR-448-3p level was significantly decreased and the dipeptidyl peptidase-4 (DPP-4) messenger RNA level was increased in diabetic animal and cell models, which was reversed by miR-448-3p treatment. Moreover, the diabetic rats exhibited endothelial damage and endothelial-mesenchymal transition (EndMT), while AAV2-miR-448-3p injection relieved those situations. In vitro experiments demonstrated that miR-448-3p overexpression in endothelial cells alleviated endothelial damage by inhibiting EndMT through blocking the transforming growth factor-β/Smad pathway. We further proved that miR-448-3p negatively regulated DPP-4 by binding to its 3'-untranslated region, and DPP-4 overexpression reversed the effect of miR-448-3p overexpression on EndMT. Overall, we conclude that miR-448-3p overexpression inhibits EndMT via targeting DPP-4 and further ameliorates diabetic vascular endothelial dysfunction, indicating that miR-448-3p may serve as a promising therapeutic target for diabetic endothelial dysfunction.

Nur77 deficiency exacerbates cardiac fibrosis after myocardial infarction by promoting endothelial-to-mesenchymal transition

Cardiac fibrosis is a reparative process after myocardial infarction (MI), which leads to cardiac remodeling and finally heart failure. Endothelial-to-mesenchymal transition (EndMT) is induced after MI and contributes to cardiac fibrosis after MI. Orphan nuclear receptor Nur77 is a key regulator of inflammation, angiogenesis, proliferation, and apoptosis in vascular endothelial cells. Here, we investigated the role of orphan nuclear receptor Nur77 in EndMT and cardiac fibrosis after MI. Cardiac fibrosis was induced through MI by ligation of the left anterior descending coronary artery. We demonstrated that Nur77 knockout aggravated cardiac dysfunction and cardiac fibrosis 30 days after MI. Moreover, Nur77 deficiency resulted in enhanced EndMT as shown by increased expression of FSP-1, SM22α, Snail, and decreased expression of PECAM-1 and eNOS compared with wild-type mice after MI. Then, we found overexpression Nur77 in human coronary artery endothelial cells significantly inhibited interleukin 1β and transforming growth factor β2-induced EndMT, as shown by a reduced transition to a fibroblast-like phenotype and preserved angiogenesis potential. Mechanistically, we demonstrated that Nur77 downregulated EndMT by inhibiting the nuclear factor-κB-dependent pathway. In conclusion, Nur77 is involved in cardiac fibrosis by inhibiting EndMT and may be a promising target for therapy of cardiac fibrosis after MI.

Endothelial-to-Mesenchymal Transition in Calcific Aortic Valve Disease

Calcific aortic valve disease (CAVD) represents a significant threat to cardiovascular health worldwide, and the incidence of this sclerocalcific valve disease has rapidly increased along with a rise in life expectancy. Compelling evidence has suggested that CAVD is an actively and finely regulated pathophysiological process even though it has been referred to as "degenerative" for decades. A striking similarity has been noted in the etiopathogenesis between CAVD and atherosclerosis, a classical proliferative sclerotic vascular disease.1 Nevertheless, pharmaceutical trials that attempted to target inflammation and dyslipidemia have produced disappointing results in CAVD. While senescence is a well-documented risk factor, the sophisticated regulatory networks have not been adequately explored underlying the aberrant calcification and osteogenesis in CAVD. Valvular endothelial cells (VECs), a type of resident effector cells in aortic leaflets, are crucial in maintaining valvular integrity and homeostasis, and dysfunctional VECs are a major contributor to disease initiation and progression. Accumulating evidence suggests that VECs undergo a phenotypic and functional transition to mesenchymal or fibroblast-like cells in CAVD, a process known as the endothelial-to-mesenchymal transition (EndMT) process. The relevance of this transition in CAVD has recently drawn great interest due to its importance in both valve genesis at an embryonic stage and CAVD development at an adult stage. Hence EndMT might be a valuable diagnostic and therapeutic target for disease prevention and treatment. This mini-review summarized the relevant literature that delineates the EndMT process and the underlying regulatory networks involved in CAVD.

EOFAZ inhibits endothelial‑to‑mesenchymal transition through downregulation of KLF4

Essential oil from Alpinia zerumbet rhizome (EOFAZ), which is termed Yan shanjiang in China, is extensively used as an herbal medicine in the Guizhou area and has been shown to protect against the damaging effects of cardiovascular injury in vitro and in vivo. In the present study, it was hypothesized that the protective effects of EOFAZ on transforming growth factor (TGF)-β1-induced endothelial-to-mesenchymal transition (EndMT) in human umbilical vein endothelial cells (HUVECs) were mediated by inhibition of Krüppel-like factor 4 (KLF4). Cell motility was assessed using wound healing and Transwell assays. The expression of endothelial markers and mesenchymal markers were determined by reverse transcription-quantitative PCR, immunofluorescence staining and western blotting, and additionally, phosphorylated NF-κB p65 expression was determined by western blotting. Furthermore, the involvement of KLF4 in EndMT was determined using RNA interference to knockdown the expression of KLF4. TGF-β1 treatment significantly promoted EndMT, as evidenced by downregu-lation of vascular endothelial-cadherin and upregulation of α-smooth muscle actin in HUVECs, and by enhancing cell migration. Small interfering RNA-mediated knockdown of KLF4 reversed TGF-β1-induced EndMT. Additionally, treatment with EOFAZ inhibited TGF-β1-induced EndMT in a dose-dependent manner. These results suggest that TGF-β1 may induce EndMT through upregulation of KLF4, and this may be reversed by EOFAZ. Therefore, EOFAZ was shown to inhibit TGF-β1-induced EndMT through regulation of KLF4.

A Computational Model of the Endothelial to Mesenchymal Transition

Endothelial cells (ECs) form the lining of lymph and blood vessels. Changes in tissue requirements or wounds may cause ECs to behave as tip or stalk cells. Alternatively, they may differentiate into mesenchymal cells (MCs). These processes are known as EC activation and endothelial-to-mesenchymal transition (EndMT), respectively. EndMT, Tip, and Stalk EC behaviors all require SNAI1, SNAI2, and Matrix metallopeptidase (MMP) function. However, only EndMT inhibits the expression of VE-cadherin, PECAM1, and VEGFR2, and also leads to EC detachment. Physiologically, EndMT is involved in heart valve development, while a defective EndMT regulation is involved in the physiopathology of cardiovascular malformations, congenital heart disease, systemic and organ fibrosis, pulmonary arterial hypertension, and atherosclerosis. Therefore, the control of EndMT has many promising potential applications in regenerative medicine. Despite the fact that many molecular components involved in EC activation and EndMT have been characterized, the system-level molecular mechanisms involved in this process have not been elucidated. Toward this end, hereby we present Boolean network model of the molecular involved in the regulation of EC activation and EndMT. The simulated dynamic behavior of our model reaches fixed and cyclic patterns of activation that correspond to the expected EC and MC cell types and behaviors, recovering most of the specific effects of simple gain and loss-of-function mutations as well as the conditions associated with the progression of several diseases. Therefore, our model constitutes a theoretical framework that can be used to generate hypotheses and guide experimental inquiry to comprehend the regulatory mechanisms behind EndMT. Our main findings include that both the extracellular microevironment and the pattern of molecular activity within the cell regulate EndMT. EndMT requires a lack of VEGFA and sufficient oxygen in the extracellular microenvironment as well as no FLI1 and GATA2 activity within the cell. Additionally Tip cells cannot undergo EndMT directly. Furthermore, the specific conditions that are sufficient to trigger EndMT depend on the specific pattern of molecular activation within the cell.

Rapamycin promotes endothelial-mesenchymal transition during stress-induced premature senescence through the activation of autophagy

Background

Rapamycin is known to be effective in suppressing senescence and the senescence-associated secretory phenotype (SASP). Therefore, it is highly expected to represent an anti-aging drug. Its anti-aging effect has been demonstrated at the mouse individual level. However, there are not many clinical findings with respect to its activity in humans. Here, we aimed to clarify the effect of rapamycin on human endothelial cells (ECs) as an in vitro model of human blood vessels.

Methods

Over the course of oxidative stress-induced senescence using hydrogen peroxide, we examined the effect of rapamycin on human coronary artery ECs (HCAECs). Senescence was evaluated by detecting senescence-associated β-galactosidase (SA-β-Gal) activity and the real-time PCR analysis of p16^INK4a. Furthermore, expression levels of SASP factors were examined by real-time PCR and the expression of senescence-related antigens, such as intercellular adhesion molecule-1 (ICAM-1) and ganglioside GM1, were examined by fluorescence-activated cell sorting analysis and immunostaining. The inhibitory effect of rapamycin on mTOR signaling was examined by immunoblotting. The adhesion of leukocytes to HCAECs was evaluated by adhesion assays. Endothelial–mesenchymal transition (EndMT) induced by rapamycin treatment was evaluated by real-time PCR analysis and immunostaining for EndMT markers. Finally, we checked the activation of autophagy by immunoblotting and examined its contribution to EndMT by using a specific inhibitor. Furthermore, we examined how the activation of autophagy influences TGF-β signaling by immunoblotting for Smad2/3 and Smad7.

Results

A decrease in SA-β-Gal activity and the suppression of SASP factors were observed in HCAECs undergoing stress-induced premature senescence (SIPS) after rapamycin treatment. In contrast, ICAM-1 and ganglioside GM1 were upregulated by rapamycin treatment. In addition, leukocyte adhesion to HCAECs was promoted by this treatment. In rapamycin-treated HCAECs, morphological changes and the promotion of EndMT were also observed. Furthermore, we found that autophagy activation induced by rapamycin treatment, which led to activation of the TGF-β pathway, contributed to EndMT induction.

Conclusions

We revealed that although rapamycin functions to inhibit senescence and suppress SASP in HCAECs undergoing SIPS, EndMT is induced due to the activation of autophagy.

Gremlin-1 is a key regulator of endothelial-to-mesenchymal transition in human pulmonary artery endothelial cells

BACKGROUND

Endothelial-to-mesenchymal transition (EndMT) has been implicated in initiation and progression of pulmonary arterial hypertension (PAH). Gremlin-1 promotes vascular remodeling of PAH and mediates epithelial-mesenchymal transition, which is similar to EndMT. In the present study we investigated the potential role of gremlin-1 plays in EndMT of pulmonary artery endothelial cells (PAECs).

METHODS

Immunofluorescence staining was performed to detect the expression of alpha smooth muscle actin (α-SMA) and von Willebrand factor (VWF). Migration and angiogenic responses of PAECs were determined by transwell assay and tube formation assay, respectively. Protein expression levels were determined by western blotting.

RESULTS

Gremlin-1 induced EndMT of PAECs in a phospho-smad2/3-dependent manner. This was characterized by the loss of platelet endothelial cell adhesion molecule 1 and an increase in protein levels of a-SMA, nerve-cadherin, and matrix metalloproteinase 2. It was also determined that gremlin-1 facilitated the migration and angiogenic responses of PAECs in a dose-dependent manner. Bone morphogenetic protein 7 (BMP-7) was found to attenuate gremlin-1-mediated EndMT, migration and angiogenesis of PAECs by inducing phosphorylation of Smad1/5/8 and suppressing phosphorylation of Smad2/3.

CONCLUSION

Gremlin-1 mediates EndMT in PAECs, and BMP-7 reverses gremlin-1-induced EndMT by an induction of p-Smad1/5/8 and suppression of p-Smad2/3.

Endothelial Dysfunction in Obesity-Induced Inflammation: Molecular Mechanisms and Clinical Implications

Obesity is characterized by the excessive deposition of fat that may interfere with the normal metabolic process of the body. It is a chronic condition associated with various metabolic syndromes, whose prevalence is grossly increasing, and affects both children and adults. Accumulation of excessive macronutrients on the adipose tissues promotes the secretion and release of inflammatory mediators, including interleukin-6 (IL-6), interleukin 1β, tumor necrotic factor-α (TNF-α), leptin, and stimulation of monocyte chemoattractant protein-1 (MCP-1), which subsequently reduce the production of adiponectin thereby initiating a proinflammatory state. During obesity, adipose tissue synthesizes and releases a large number of hormones and cytokines that alter the metabolic processes, with a profound influence on endothelial dysfunction, a situation associated with the formation of atherosclerotic plaque. Endothelial cells respond to inflammation and stimulation of MCP-1, which is described as the activation of adhesion molecules leading to proliferation and transmigration of leukocytes, which facilitates their increase in atherogenic and thromboembolic potentials. Endothelial dysfunction forms the cornerstone of this discussion, as it has been considered as the initiator in the progression of cardiovascular diseases in obesity. Overexpression of proinflammatory cytokines with subsequent reduction of anti-inflammatory markers in obesity, is considered to be the link between obesity-induced inflammation and endothelial dysfunction. Inhibition of inflammatory mechanisms and management and control of obesity can assist in reducing the risks associated with cardiovascular complications.

Cardiomyocyte Senescence and Cellular Communications Within Myocardial Microenvironments

Cardiovascular diseases have become the leading cause of human death. Aging is an independent risk factor for cardiovascular diseases. Cardiac aging is associated with maladaptation of cellular metabolism, dysfunction (or senescence) of cardiomyocytes, a decrease in angiogenesis, and an increase in tissue scarring (fibrosis). These events eventually lead to cardiac remodeling and failure. Senescent cardiomyocytes show the hallmarks of DNA damage, endoplasmic reticulum stress, mitochondria dysfunction, contractile dysfunction, hypertrophic growth, and senescence-associated secreting phenotype (SASP). Metabolism within cardiomyocytes is essential not only to fuel the pump function of the heart but also to maintain the functional homeostasis and participate in the senescence of cardiomyocytes. The senescence of cardiomyocyte is also regulated by the non-myocytes (endothelial cells, fibroblasts, and immune cells) in the local microenvironment. On the other hand, the senescent cardiomyocytes alter their phenotypes and subsequently affect the non-myocytes in the local microenvironment and contribute to cardiac aging and pathological remodeling. In this review, we first summarized the hallmarks of the senescence of cardiomyocytes. Then, we discussed the metabolic switch within senescent cardiomyocytes and provided a discussion of the cellular communications between dysfunctional cardiomyocytes and non-myocytes in the local microenvironment. We also addressed the functions of metabolic regulators within non-myocytes in modulating myocardial microenvironment. Finally, we pointed out some interesting and important questions that are needed to be addressed by further studies.

Vascular Diseases and Gangliosides

Vascular diseases, such as myocardial infarction and cerebral infarction, are most commonly caused by atherosclerosis, one of the leading causes of death worldwide. Risk factors for atherosclerosis include lifestyle and aging. It has been reported that lifespan could be extended in mice by targeting senescent cells, which led to the suppression of aging-related diseases, such as vascular diseases. However, the molecular mechanisms underlying the contribution of aging to vascular diseases are still not well understood. Several types of cells, such as vascular (endothelial cell), vascular-associated (smooth muscle cell and fibroblast) and inflammatory cells, are involved in plaque formation, plaque rupture and thrombus formation, which result in atherosclerosis. Gangliosides, a group of glycosphingolipids, are expressed on the surface of vascular, vascular-associated and inflammatory cells, where they play functional roles. Clarifying the role of gangliosides in atherosclerosis and their relationship with aging is fundamental to develop novel prevention and treatment methods for vascular diseases based on targeting gangliosides. In this review, we highlight the involvement and possible contribution of gangliosides to vascular diseases and further discuss their relationship with aging.

Systems-wide analysis unravels the new roles of CCM signal complex (CSC)

Cerebral cavernous malformations (CCMs) are characterized by abnormally dilated intracranial capillaries that result in increased susceptibility to stroke. Three genes have been identified as causes of CCMs; KRIT1 (CCM1), MGC4607 (CCM2) and PDCD10 (CCM3); one of them is disrupted in most CCM cases. It was demonstrated that both CCM1 and CCM3 bind to CCM2 to form a CCM signaling complex (CSC) to modulate angiogenesis. In this report, we deployed both RNA-seq and proteomic analysis of perturbed CSC after depletion of one of three CCM genes to generate interactomes for system-wide studies. Our results demonstrated a unique portrait detailing alterations in angiogenesis and vascular integrity. Interestingly, only in-direct overlapped alterations between RNA and protein levels were detected, supporting the existence of multiple layers of regulation in CSC cascades. Notably, this is the first report identifying that both β4 integrin and CAV1 signaling are downstream of CSC, conveying the angiogenic signaling. Our results provide a global view of signal transduction modulated by the CSC, identifies novel regulatory signaling networks and key cellular factors associated with CSC.

rhBMP‑7 suppresses TGF‑β1‑induced endothelial to mesenchymal transition in circulating endothelial cells by regulating Smad5

Endothelial to mesenchymal transition (EndMT) has been confirmed to participate in several cardiovascular diseases. In addition, EndMT of circulating endothelial cells (CECs) contributes to the pathology of musculoskeletal injury. However, little is known about the molecular mechanism of CECs undergoing EndMT. In the present study, human CECs were isolated and identified using anti‑CD146‑coupled magnetic beads. CECs were exposed to transforming growth factor (TGF)‑β1 or TGF‑β1 + recombinant human bone morphogenetic protein 7 (rhBMP‑7) or TGF‑β1 + rhBMP‑7 + Smad5 antagonist Jun activation domain‑binding protein 1. Vascular endothelial (VE)‑cadherin and vimentin expression were detected by immunofluorescence staining in TGF‑β1‑treated CECs. The expression levels of von Willebrand factor (vWF), E‑selectin, VE‑cadherin, vimentin, fibronectin, α smooth muscle actin (α‑SMA) and Smad2/3 were detected by reverse transcription‑quantitative PCR or western blot analysis. It was identified that rhBMP‑7 attenuated TGF‑β1‑induced endothelial cell injury. TGF‑β1 could induce the EndMT process in CECs, as confirmed by the co‑expression of VE‑cadherin and vimentin. TGF‑β1 significantly reduced the expression of VE‑cadherin, and induced the expression of vimentin, fibronectin and α‑SMA. rhBMP‑7 reversed the effects of TGF‑β1 on the expression of these genes. Additionally, Smad5 antagonist reversed the effects of rhBMP‑7 on TGF‑β1‑induced EndMT, and upregulated rhBMP‑7‑inhibited Smad2/3 expression. In conclusion, TGF‑β1 could induce EndMT in CECs and rhBMP‑7 may suppress this process by regulating Smad5.

Inhibition of miR-21 alleviated cardiac perivascular fibrosis via repressing EndMT in T1DM

In type 1 and type 2 diabetes mellitus, increased cardiac fibrosis, stiffness and associated diastolic dysfunction may be the earliest pathological phenomena in diabetic cardiomyopathy. Endothelial-mesenchymal transition (EndMT) in endothelia cells (ECs) is a critical cellular phenomenon that increases cardiac fibroblasts (CFs) and cardiac fibrosis in diabetic hearts. The purpose of this paper is to explore the molecular mechanism of miR-21 regulating EndMT and cardiac perivascular fibrosis in diabetic cardiomyopathy. In vivo, hyperglycaemia up-regulated the mRNA level of miR-21, aggravated cardiac dysfunction and collagen deposition. The condition was recovered by inhibition of miR-21 following with improving cardiac function and decreasing collagen deposition. miR-21 inhibition decreased cardiac perivascular fibrosis by suppressing EndMT and up-regulating SMAD7 whereas activating p-SMAD2 and p-SMAD3. In vitro, high glucose (HG) up-regulated miR-21 and induced EndMT in ECs, which was decreased by inhibition of miR-21. A highly conserved binding site of NF-κB located in miR-21 5'-UTR was identified. In ECs, SMAD7 is directly regulated by miR-21. In conclusion, the pathway of NF-κB/miR-21/SMAD7 regulated the process of EndMT in T1DM, in diabetic cardiomyopathy, which may be regarded as a potential clinical therapeutic target for cardiac perivascular fibrosis.

Nintedanib ameliorates experimental pulmonary arterial hypertension via inhibition of endothelial mesenchymal transition and smooth muscle cell proliferation

Neointimal lesion and medial wall thickness of pulmonary arteries (PAs) are common pathological findings in pulmonary arterial hypertension (PAH). Platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF) signaling contribute to intimal and medial vascular remodeling in PAH. Nintedanib is a tyrosine kinase inhibitor whose targets include PDGF and FGF receptors. Although the beneficial effects of nintedanib were demonstrated for human idiopathic pulmonary fibrosis, its efficacy for PAH is still unclear. Thus, we hypothesized that nintedanib is a novel treatment for PAH to inhibit the progression of vascular remodeling in PAs. We evaluated the inhibitory effects of nintedanib both in endothelial mesenchymal transition (EndMT)-induced human pulmonary microvascular endothelial cells (HPMVECs) and human pulmonary arterial smooth muscle cells (HPASMCs) stimulated by growth factors. We also tested the effect of chronic nintedanib administration on a PAH rat model induced by Sugen5416 (a VEGF receptor inhibitor) combined with chronic hypoxia. Nintedanib was administered from weeks 3 to 5 after Sugen5416 injection, and we evaluated pulmonary hemodynamics and PAs pathology. Nintedanib attenuated the expression of mesenchymal markers in EndMT-induced HPMVECs and HPASMCs proliferation. Phosphorylation of PDGF and FGF receptors was augmented in both intimal and medial lesions of PAs. Nintedanib blocked these phosphorylation, improved hemodynamics and reduced vascular remodeling involving neointimal lesions and medial wall thickening in PAs. Additionally, expressions Twist1, transcription factors associated with EndMT, in lung tissue was significantly reduced by nintedanib. These results suggest that nintedanib may be a novel treatment for PAH with anti-vascular remodeling effects.