Endothelial to mesenchymal transition in atherosclerotic vascular remodeling

Melatonin alleviates myocardial dysfunction through inhibition of endothelial-to-mesenchymal transition via the NF-κB pathway

Endothelial-to-mesenchymal transition (EndMT) is a complex biological process of cellular transdifferentiation by which endothelial cells (ECs) lose their characteristics and acquire mesenchymal properties, leading to cardiovascular remodeling and complications in the adult cardiovascular diseases environment. Melatonin is involved in numerous physiological and pathological processes, including aging, and has anti-inflammatory and antioxidant activities. This molecule is an effective therapeutic candidate for preventing oxidative stress, regulating endothelial function, and maintaining the EndMT balance to provide cardiovascular protection. Although recent studies have documented improved cardiac function by melatonin, the mechanism of action of melatonin on EndMT remains unclear. The present study investigated the effects of melatonin on induced EndMT by transforming growth factor-β2/interleukin-1β in both in vivo and in vitro models. The results revealed that melatonin reduced the migratory ability and reactive oxygen species levels of the cells and ameliorated mitochondrial dysfunction in vitro. Our findings indicate that melatonin prevents endothelial dysfunction and inhibits EndMT by activating related pathways, including nuclear factor kappa B and Smad. We also demonstrated that this molecule plays a crucial role in restoring cardiac function by regulating the EndMT process in the ischemic myocardial condition, both in vessel organoids and myocardial infarction (MI) animal models. In conclusion, melatonin is a promising agent that attenuates EC dysfunction and ameliorates cardiac damage compromising the EndMT process after MI.

Fluid shear stress induced-endothelial phenotypic transition contributes to cerebral ischemia-reperfusion injury and repair

Long-term ischemia leads to insufficient cerebral microvascular perfusion and dysfunction. Reperfusion restores physiological fluid shear stress (FSS) but leads to serious injury. The mechanism underlying FSS-induced endothelial injury in ischemia-reperfusion injury (IRI) remains poorly understood. In this study, a rat model of middle cerebral artery occlusion was constructed to explore cerebrovascular endothelial function and inflammation in vivo. Additionally, the rat brain microvascular endothelial cells (rBMECs) were exposed to a laminar FSS of 0.5 dyn/cm2 for 6 h and subsequently restored to physiological fluid shear stress level (2 dyn/cm2) for 2 and 12 h, respectively. We found that reperfusion induced endothelial-to-mesenchymal transition (EndMT) in endothelial cells, leading to serious blood-brain barrier dysfunction and endothelial inflammation, accompanied by the nuclear accumulation of Yes-associated protein (YAP). During the later stage of reperfusion, cerebral endothelium was restored to the endothelial phenotype with a distinct change in mesenchymal-to-endothelial transition (MEndT), while YAP was translocated and phosphorylated in the cytoplasm. Knockdown of YAP or inhibition of actin polymerization markedly impaired the EndMT in rBMECs. These findings suggest that ischemia-reperfusion increased intensity of FSS triggered an EndMT process and, thus, led to endothelial inflammation and tissue injury, whereas continuous FSS induced a time-dependent reversal MEndT event contributing to the endothelial repair. This study provides valuable insight for therapeutic strategies targeting IRI.

Insights into the Mechanism of Supramolecular Self-Assembly in the Astragalus membranaceus-Angelica sinensis Codecoction

Astragalus membranaceus (Fisch.) Bge. (AM) and Angelica sinensis (Oliv.) Diels (AS) constitute a classic herb pair in prescriptions to treat myocardial fibrosis. To date, research on the AM-AS herb pair has mainly focused on the chemical compositions associated with therapeutic efficacy. However, supermolecules actually exist in herb codecoctions, and their self-assembly mechanism remains unclear. In this study, supermolecules originating from AM-AS codoping reactions (AA-NPs) were first reported. The chemical compositions of AA-NPs showed a dynamic self-assembly process. AA-NPs with different decoction times had similar surface groups and amorphous states; however, the size distributions of these nanoparticles might be different. Taking the interaction between Z-ligustilide and astragaloside IV as an example to understand the self-assembly mechanism of AA-NPs, it was found that the complex could be formed with a molar ratio of 2:1. Later, AA-NPs were proven to be effective in the treatment of myocardial fibrosis both in vivo and in vitro, the in-depth mechanisms of which were related to the recovery of cardiac function, reduced collagen deposition, and inhibition of the endothelial-to-mesenchymal transition that occurred in the process of myocardial fibrosis. Thus, AA-NPs may be the chemical material basis of the molecular mechanism of the AM-AS decoction in treating isoproterenol-induced myocardial fibrosis. Taken together, this work provides a supramolecular strategy for revealing the interaction between effective chemical components in herb-pair decoctions.

Single-cell RNA-seq uncovers distinct pathways and genes in endothelial cells during atherosclerosis progression

Background: Atherosclerosis (AS) is a chronic inflammatory disease involving various cell types, cytokines, and adhesion molecules. Herein, we aimed to uncover its key molecular mechanisms by single-cell RNA-seq (scRNA-seq) analysis. Methods: ScRNA-seq data of cells from atherosclerotic human coronary arteries were analyzed using the Seurat package. Cell types were clustered, and differentially expressed genes (DEGs) were screened. GSVA (Gene Set Variation Analysis) scores of hub pathways were compared among different cell clusters. DEGs in endothelial cells between apolipoprotein-E (ApoE)^-/- mice and specific TGFbR1/2 KO ApoE^-/- mice fed with high-fat diet were overlapped with those from human AS coronary arteries. In fluid shear stress and AS, hub genes were determined based on the protein-protein interaction (PPI) network, which were verified in ApoE^-/- mice. Finally, hub genes were validated in three pairs of AS coronary arteries and normal tissues by histopathological examination. Results: ScRNA-seq identified nine cell clusters in human coronary arteries, namely, fibroblasts, endothelial cells, macrophages, B cells, adipocytes, HSCs, NK cells, CD8⁺ T cells, and monocytes. Among them, endothelial cells had the lowest fluid shear stress and AS and TGF-beta signaling pathway scores. Compared to ApoE^-/- mice fed with normal diet, fluid shear stress and AS and TGF-beta scores were both significantly lower in endothelial cells from TGFbR1/2 KO ApoE^-/- mice fed with normal or high-fat diet. Furthermore, the two hub pathways had a positive correlation. Three hub genes (ICAM1, KLF2, and VCAM1) were identified, and their expression was distinctly downregulated in endothelial cells from TGFbR1/2 KO ApoE^-/- mice fed with normal or high-fat diet than in those from ApoE^-/- mice fed with a normal diet, which were confirmed in human AS coronary artery. Conclusion: Our findings clarified the pivotal impacts of pathways (fluid shear stress and AS and TGF-beta) and genes (ICAM1, KLF2, and VCAM1) in endothelial cells on AS progression.

The PPAR-γ Agonist Pioglitazone Modulates Proliferation and Migration in HUVEC, HAOSMC and Human Arteriovenous Fistula-Derived Cells

The failure of arteriovenous fistulas (AVFs) following intimal hyperplasia (IH) increases morbidity and mortality rates in patients undergoing hemodialysis for chronic kidney disease. The peroxisome-proliferator associated receptor (PPAR-γ) may be a therapeutic target in IH regulation. In the present study, we investigated PPAR-γ expression and tested the effect of pioglitazone, a PPAR-γ agonist, in different cell types involved in IH. As cell models, we used Human Endothelial Umbilical Vein Cells (HUVEC), Human Aortic Smooth Muscle Cells (HAOSMC), and AVF cells (AVFCs) isolated from (i) normal veins collected at the first AVF establishment (T0), and (ii) failed AVF with IH (T1). PPAR-γ was downregulated in AVF T1 tissues and cells, in comparison to T0 group. HUVEC, HAOSMC, and AVFC (T0 and T1) proliferation and migration were analyzed after pioglitazone administration, alone or in combination with the PPAR-γ inhibitor, GW9662. Pioglitazone negatively regulated HUVEC and HAOSMC proliferation and migration. The effect was antagonized by GW9662. These data were confirmed in AVFCs T1, where pioglitazone induced PPAR-γ expression and downregulated the invasive genes SLUG, MMP-9, and VIMENTIN. In summary, PPAR-γ modulation may represent a promising strategy to reduce the AVF failure risk by modulating cell proliferation and migration.

Growth State-Dependent Expression of Arachidonate Lipoxygenases in the Human Endothelial Cell Line EA.hy926

Endothelial cells regulate vascular homeostasis through the secretion of various paracrine molecules, including bioactive lipids, but little is known regarding the enzymes responsible for generating these lipids under either physiological or pathophysiological conditions. Arachidonate lipoxygenase (ALOX) expression was therefore investigated in confluent and nonconfluent EA.h926 endothelial cells, which represent the normal quiescent and proliferative states, respectively. mRNAs for ALOX15, ALOX15B, and ALOXE3 were detected in EA.hy926 cells, with the highest levels present in confluent cells compared to nonconfluent cells. In contrast, ALOX5, ALOX12, and ALOX12B mRNAs were not detected. At the protein level, only ALOX15B and ALOXE3 were detected but only in confluent cells. ALOXE3 was also observed in confluent human umbilical artery endothelial cells (HUAEC), indicating that its expression, although previously unreported, may be a general feature of endothelial cells. Exposure to laminar flow further increased ALOXE3 levels in EA.hy926 cells and HUAECs. The evidence obtained in this study indicates that proliferative status and shear stress are both important factors that mediate endothelial ALOX gene expression. The presence of ALOX15B and ALOXE3 exclusively in quiescent human endothelial cells suggests their activity likely contributes to the maintenance of a healthy endothelium.

Epigallocatechin-3-Gallate (EGCG) Mitigates Endothelial and Circulating Cells Alterations Following PLLA Electrospun Mat Placement

Background. Synthetic vascular graft calcification is a serious complication of graft placement. Here, we analysed migration and osteogenic genes of human umbilical vein endothelial cells (HUVEC) cultured with a poly-L-lactic acid (PLLA) electrospun mat. The role of epigallo-catechin-3-gallate (EGCG) in pathogenic processes involving HUVEC and peripheral blood mononuclear cells (PBMCs) was also tested. Methods. HUVEC were cultured in indirect contact with PLLA for 48 h, with or without EGCG, and processed for mRNA expression. HUVEC proliferation, migration and osteogenic differentiation were evaluated after EGCG treatment. EGCG was also administrated to human PBMCs, to analyse proliferation and migration toward HUVEC cultured with PLLA. Results. HUVEC cultured with PLLA exhibited increased expression of SLUG, VIMENTIN, MMP-9 (migration, vascular remodelling) and RUNX-2 (osteogenic transcription factor). EGCG at 25 μM significantly reduced HUVEC migration, osteogenic differentiation, without affecting cell viability, and mitigated PLLA influence on SLUG, MMP-9, VIMENTIN and RUNX-2 expression. EGCG affected PBMC proliferation and migration toward PLLA in a transwell co-culture system with HUVEC. Conclusion. Our study suggests the pro-calcific effect of PLLA, proposing EGCG as an anti-inflammatory modulatory approach. Research efforts need to deepen PLLA-vascular wall interactions for preventing vascular graft failure.

Epithelial-mesenchymal transition in organ fibrosis development: current understanding and treatment strategies

Organ fibrosis is a process in which cellular homeostasis is disrupted and extracellular matrix is excessively deposited. Fibrosis can lead to vital organ failure and there are no effective treatments yet. Although epithelial–mesenchymal transition (EMT) may be one of the key cellular mechanisms, the underlying mechanisms of fibrosis remain largely unknown. EMT is a cell phenotypic process in which epithelial cells lose their cell-to-cell adhesion and polarization, after which they acquire mesenchymal features such as infiltration and migration ability. Upon injurious stimulation in different organs, EMT can be triggered by multiple signaling pathways and is also regulated by epigenetic mechanisms. This narrative review summarizes the current understanding of the underlying mechanisms of EMT in fibrogenesis and discusses potential strategies for attenuating EMT to prevent and/or inhibit fibrosis. Despite better understanding the role of EMT in fibrosis development, targeting EMT and beyond in developing therapeutics to tackle fibrosis is challenging but likely feasible.

Research Progress on the Role of Intermediate Filament Vimentin in Atherosclerosis

The cytoskeleton is a biopolymer network composed of intermediate filaments, actin, and microtubules, which is the main mechanical structure of cells. Vimentin is an intermediate filament protein that regulates the mechanical and contractile properties of cells, thereby reflecting their mechanical properties. In recent years, the "nonmechanical function" of vimentin inside and outside of cells has attracted extensive attention. The content of vimentin in atherosclerotic plaques is increased, and the serum secretion of vimentin in patients with coronary heart disease is remarkably increased. In this review, the mechanistic and nonmechanistic roles of vimentin in atherosclerosis progression were summarized on the basis of current studies.

Detection of Atherosclerosis by Small RNA-Sequencing Analysis of Extracellular Vesicle Enriched Serum Samples

Atherosclerosis can occur throughout the arterial vascular system and lead to various diseases. Early diagnosis of atherosclerotic processes and of individual disease patterns would be more likely to be successful if targeted therapies were available. For this, it is important to find reliable biomarkers that are easily accessible and with little inconvenience for patients. There are many cell culture, animal model or tissue studies that found biomarkers at the microRNA (miRNA) and mRNA level describing atherosclerotic processes. However, little is known about their potential as circulating and liquid biopsy markers in patients. In this study, we examined serum-derived miRNA - profiles from 129 patients and 28 volunteers to identify potential biomarkers. The patients had four different atherosclerotic manifestations: abdominal aneurysm (n = 35), coronary heart disease (n = 34), carotid artery stenosis (n = 24) and peripheral arterial disease (n = 36). The samples were processed with an extracellular vesicle enrichment protocol, total-RNA extraction and small RNA-sequencing were performed. A differential expression analysis was performed bioinformatically to find potentially regulated miRNA biomarkers. Resulting miRNA candidates served as a starting point for an overrepresentation analysis in which relevant target mRNAs were identified. The Gene Ontology database revealed relevant biological functions in relation to atherosclerotic processes. In patients, expression of specific miRNAs changed significantly compared to healthy volunteers; 27 differentially expressed miRNAs were identified. We were able to detect a group-specific miRNA fingerprint: miR-122-5p, miR-2110 and miR-483-5p for abdominal aortic aneurysm, miR-370-3p and miR-409-3p for coronary heart disease, miR-335-3p, miR-381-3p, miR493-5p and miR654-3p for carotid artery stenosis, miR-199a-5p, miR-215-5p, miR-3168, miR-582-3p and miR-769-5p for peripheral arterial disease. The results of the study show that some of the identified miRNAs have already been associated with atherosclerosis in previous studies. Overrepresentation analysis on this data detected biological processes that are clearly relevant for atherosclerosis, its development and progression showing the potential of these miRNAs as biomarker candidates. In a next step, the relevance of these findings on the mRNA level is to be investigated and substantiated.

MiR-200c-3p promotes ox-LDL-induced endothelial to mesenchymal transition in human umbilical vein endothelial cells through SMAD7/YAP pathway

BACKGROUND

Endothelial to mesenchymal transition (EndMT) participates in the progression of atherosclerosis (AS). MiR-200c-3p has been implicated in EndMT. However, the functional role of miR-200c-3p in AS remains largely unknown. Here, we demonstrated the critical role of miR-200c-3p in regulating EndMT in AS.

METHODS

ApoE-/- mice were fed with high-fat diet to establish AS mouse model, and human umbilical vein endothelial cells (HUVECs) were treated with oxidized low-density lipoprotein (ox-LDL) to mimic AS cell model. The expression of miR-200c-3p, SMAD7 and YAP in ApoE-/- mice and HUVECs was detected by quantitative real-time PCR. Rhodamine phalloidin staining and Western blot were performed to observe cell morphology and EndMT marker expression of HUVECs. Luciferase reporter assay and Co-Immunoprecipitation were performed to verify the relationship among miR-200c-3p, SMAD7, and YAP.

RESULTS

MiR-200c-3p was highly expressed, and SMAD7 and YAP were down-regulated in the aortic tissues of ApoE-/- mice and ox-LDL-treated HUVECs. MiR-200c-3p overexpression promoted the transformation of ox-LDL-treated HUVECs from cobblestone-like epithelial phenotype to a spindle-like mesenchymal phenotype. Meanwhile, miR-200c-3p up-regulation repressed the expression of endothelial markers CD31 and vWF and promoted the expression of mesenchymal markers α-SMA and vimentin in the ox-LDL-treated HUVECs. MiR-200c-3p inhibited SMAD7 and YAP expression by interacting with 3' untranslated region of SMAD7. Moreover, miR-200c-3p promoted EndMT in ox-LDL-treated HUVECs by inhibiting SMAD7/YAP pathway.

CONCLUSION

This work demonstrated that MiR-200c-3p promoted ox-LDL-induced EndMT in HUVECs through SMAD7/YAP pathway, which may be important for the onset of atherosclerosis.

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.

A promising field: regulating imbalance of EndMT in cardiovascular diseases

Endothelial-mesenchymal transition (EndMT) is widely involved in the occurrence and development of cardiovascular diseases. Although there is no direct evidence, it is very promising as an effective target for the treatment of these diseases. Endothelial cells need to respond to the complex cardiovascular environment through EndMT, but sustained stimuli will cause the imbalance of EndMT. Blocking the signal transduction promoting EndMT is an effective method to control the imbalance of EndMT. In particular, we also discussed the potential role of endothelial cell apoptosis and autophagy in regulating the imbalance of EndMT. In addition, promoting mesenchymal-endothelial transformation (MEndT) is also a method to control the imbalance of EndMT. However, targeting EndMT to treat cardiovascular disease still faces many challenges. By reviewing the research progress of EndMT, we have put forward some insights and translated them into challenges and opportunities for new treatment strategies for cardiovascular diseases.

Mechanical forces regulate endothelial-to-mesenchymal transition and atherosclerosis via an Alk5-Shc mechanotransduction pathway

The response of endothelial cells to mechanical forces is a critical determinant of vascular health. Vascular pathologies, such as atherosclerosis, characterized by abnormal mechanical forces are frequently accompanied by endothelial-to-mesenchymal transition (EndMT). However, how forces affect the mechanotransduction pathways controlling cellular plasticity, inflammation, and, ultimately, vessel pathology is poorly understood. Here, we identify a mechanoreceptor that is sui generis for EndMT and unveil a molecular Alk5-Shc pathway that leads to EndMT and atherosclerosis. Depletion of Alk5 abrogates shear stress-induced EndMT responses, and genetic targeting of endothelial Shc reduces EndMT and atherosclerosis in areas of disturbed flow. Tensional force and reconstitution experiments reveal a mechanosensory function for Alk5 in EndMT signaling that is unique and independent of other mechanosensors. Our findings are of fundamental importance for understanding how mechanical forces regulate biochemical signaling, cell plasticity, and vascular disease.

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.

Ginsenosides in vascular remodeling: Cellular and molecular mechanisms of their therapeutic action

Evidence is mounting that abnormal vascular remodeling (VR) is a vital pathological event that precedes many cardiovascular diseases (CVD). This provides us with a new research perspective that VR can be a pivotal target for CVD treatment and prevention. However, the current drugs for treating CVD do not fundamentally reverse VR and repair vascular function. The reason may be that a complicated regulatory network is formed between the various signaling pathways involved in VR. Recently, ginsenoside, the main active substance of ginseng, has become increasingly the focus of many researchers for its multiple targets, multiple pathways, and few side effects. Several data have revealed that ginsenosides can improve VR caused by vasodilation dysfunction, abnormal vascular structure and blood pressure. This review is intended to discuss the therapeutic effects and mechanisms of ginsenosides in some diseases involved in VR. Besides, we herein also give a new and contradictory insight into intracellular and molecular signaling of ginsenosides in all kinds of vascular cells. Most importantly, we also discuss the feasibility of ginsenosides Rb1/Rg1/Rg3 in drug development by combining the pharmacodynamics and pharmacokinetics of ginsenosides, and provide a pharmacological basis for the development of ginsenosides in clinical applications.

Attenuating Effects of Dieckol on Hypertensive Nephropathy in Spontaneously Hypertensive Rats

Hypertension induces renal fibrosis or tubular interstitial fibrosis, which eventually results in end-stage renal disease. Epithelial-to-mesenchymal transition (EMT) is one of the underlying mechanisms of renal fibrosis. Though previous studies showed that Ecklonia cava extracts (ECE) and dieckol (DK) had inhibitory action on angiotensin (Ang) I-converting enzyme, which converts Ang I to Ang II. It is known that Ang II is involved in renal fibrosis; however, it was not evaluated whether ECE or DK attenuated hypertensive nephropathy by decreasing EMT. In this study, the effect of ECE and DK on decreasing Ang II and its down signal pathway of angiotensin type 1 receptor (AT1R)/TGFβ/SMAD, which is related with the EMT and restoring renal function in spontaneously hypertensive rats (SHRs), was investigated. Either ECE or DK significantly decreased the serum level of Ang II in the SHRs. Moreover, the renal expression of AT1R/TGFβ/SMAD was decreased by the administration of either ECE or DK. The mesenchymal cell markers in the kidney of SHRs was significantly decreased by ECE or DK. The fibrotic tissue of the kidney of SHRs was also significantly decreased by ECE or DK. The ratio of urine albumin/creatinine of SHRs was significantly decreased by ECE or DK. Overall, the results of this study indicate that ECE and DK decreased the serum levels of Ang II and expression of AT1R/TGFβ/SMAD, and then decreased the EMT and renal fibrosis in SHRs. Furthermore, the decrease in EMT and renal fibrosis could lead to the restoration of renal function. It seems that ECE or DK could be beneficial for decreasing hypertensive nephropathy by decreasing EMT and renal fibrosis.

Resveratrol-Elicited PKC Inhibition Counteracts NOX-Mediated Endothelial to Mesenchymal Transition in Human Retinal Endothelial Cells Exposed to High Glucose

Diabetes-associated long-term hyperglycaemia leads to oxidative stress-mediated fibrosis in different tissues and organs. Endothelial-to-mesenchymal-transition (EndMT) appears to play a role in diabetes-associated fibrotic conditions. Here, we investigate whether EndMT is implicated in the diabetic retinopathy fibrotic process and evaluate the possibility that resveratrol could counteract EndMT by inhibiting high glucose (HG)-induced increases in ROS. Primary Human Retinal Endothelial Cells (HRECs) were either pre-treated for 24 h with 1 µM resveratrol or left untreated, then glucose (30 mM) was applied at 3-day intervals for 10 days. qRT-PCR and ELISA were used to detect mRNA or protein expression of endothelial markers (CD31, CDH5, vWF) or mesenchymal markers (VIM, αSMA and collagen I), respectively. Intracellular ROS levels were measured with carboxy-DCFDA, while NOX-associated ROS levels were evaluated using the NADPH-specific redox biosensor p47-roGFP. Treatment of HRECs with HG increased intracellular ROS levels and promoted phenotype shifting towards EndMT, evidenced by decreased expression of endothelial markers concomitant with increased expression of mesenchymal ones. HG-induced EndMT appears to be mediated by NADPH-associated ROS generation as pre-treatment of HRECs with resveratrol or the NADPH inhibitor, diphenyleneiodonium chloride (DPI), attenuated ROS production and EndMT transition, suggesting that the effect of resveratrol on HG-induced ROS occurs via down-regulation of NADPH oxidase. It is worth noting that resveratrol or Chelerythrine, a Protein kinase C (PKC) inhibitor, reduce ROS and EndMT in HG-exposed cells, suggesting that NADPH activation occurs via a PKC-dependent mechanism. Taken together, our results provide the basis for a resveratrol-based potential protective therapy to prevent diabetic-associated complications.

Pyrogallol-Phloroglucinol-6 6-Bieckol on Attenuates High-Fat Diet-Induced Hypertension by Modulating Endothelial-to-Mesenchymal Transition in the Aorta of Mice

Endothelial-to-mesenchymal transition (EndMT), which is involved in the development of various cardiovascular diseases, is induced by dyslipidemia or obesity. In dyslipidemia, the increased levels of oxidized low-density lipoproteins (oxLDL) upregulated the lectin-type oxidized LDL receptor 1 (Lox-1), which then upregulated the down signaling pathways of PKC-α/MMPs/TGF-β/SMAD2 or 3 and increased the EndMT. In this study, we investigated the effect of pyrogallol-phloroglucinol-6,6-bieckol (PPB), which is a compound of Ecklonia cava (E. cava), on decreased blood pressure (BP) by attenuating the EndMT in a high-fat diet- (HFD-) fed animal model. We also investigated PPB's attenuation effect on EndMT in oxLDL-treated mouse endothelial cells as an in vitro model. The results indicated that, in the aorta or endothelial cells of mice, the HFD or oxLDL treatment significantly increased the expression of Lox-1/PKC-α/MMP9/TGF-β/SMAD2/SMAD3. The PPB treatment significantly decreased its expression. In contrast, the HFD or oxLDL treatment significantly decreased the expression of the EC markers (PECAM-1 and vWF) while the PPB treatment significantly increased them. Moreover, the HFD or oxLDL treatment significantly increased the expression of the mesenchymal cell markers (α-SMA and vimentin) while PPB treatment significantly decreased them. PPB decreased the intima-media thickness and extracellular matrix amount of the aorta and attenuated the BP, which was increased by the HFD. In conclusion, PPB attenuated the upregulation of Lox-1/PKC-α/MMP9/TGF-β/SMAD2 and 3 and restored the EndMT in HFD-fed animals. Moreover, PPB showed a restoring effect on HFD-induced hypertension.

Activation of activin/Smad2 and 3 signaling pathway and the potential involvement of endothelial‑mesenchymal transition in the valvular damage due to rheumatic heart disease

Rheumatic heart disease (RHD) is an autoimmune disease caused by rheumatic fever following group A hemolytic streptococcal infection and primarily affects the mitral valve. RHD is currently a major global health problem. However, the exact pathological mechanisms associated with RHD-induced cardiac valve damage remain to be elucidated. The endothelial-mesenchymal transition (EndMT) serves a key role in a number of diseases with an important role in cardiac fibrosis and the activin/Smad2 and 3 signaling pathway is involved in regulating the EndMT. Nevertheless, there are no studies to date, to the best of the authors' knowledge, investigating the association between RHD and EndMT. Thus, the aim of the current study was to investigate the potential role of EndMT in cardiac valve damage and assess whether activin/Smad2 and 3 signaling was activated during RHD-induced valvular injury in a rat model of RHD induced by inactivated Group A streptococci and complete Freund's adjuvant. Inflammation and fibrosis were assessed by hematoxylin and eosin and Sirius red staining. Serum cytokine and rheumatoid factor levels were measured using ELISA kits. Expression levels of activin/Smad2 and 3 signaling pathway-related factors [activin A, Smad2, Smad3, phosphorylated (p-)Smad2 and p-Smad3], EndMT-related factors [lymphoid enhancer factor-1 (LEF-1), Snail1, TWIST, zinc finger E-box-binding homeobox (ZEB)1, ZEB2, α smooth muscle actin (α-SMA) and type I collagen α 1 (COL1A1)], apoptosis-related markers (BAX and cleaved caspase-3) and valvular inflammation markers (NF-κB and p-NF-κB) were detected using reverse transcription-quantitative PCR and western blot analyses. Compared with the control group, the degree of valvular inflammation and fibrosis, serum levels of IL-6, IL-17, TNF-α and expression of apoptosis-related markers (BAX and cleaved caspase-3) and valvular inflammation marker (p-NF-κB), activin/Smad2 and 3 signaling pathway-related factors (activin A, p-Smad2 and p-Smad3), EndMT-related factors (LEF-1, Snail1, TWIST, ZEB 1, ZEB2, α-SMA and COL1A1) were significantly increased in the RHD group. These results suggested that the activin/Smad2 and 3 signaling pathway was activated during the development of valvular damage caused by RHD and that the EndMT is involved in RHD-induced cardiac valve damage.

Ephrin B2 mediates high glucose induced endothelial-to-mesenchymal transition in human aortic endothelial cells

Background

Previous study revealed that high glucose (HG) induced endothelial cell (EC) damage via endothelial-to-mesenchymal transition (EndMT). Recent studies suggested the role of Ephrin B2 in mediate ECs damage. However, the underlying mechanism remains unclear. The aim of the present study was to investigate whether Ephrin B2 mediates HG-induced EndMT in human aortic ECs (HAECs) and to determine the possible downstream signaling effector.

Methods

Primary HAECs were exposed to normal glucose (NG, 5.5 mM), HG (30 mM) and HG+Ephrin B2 small interfering RNA (siRNA), respectively. The pathological changes were investigated by light microscope and confocal microscopy. To study the effects of focal adhesion kinase (FAK) activation on Ephrin B2 in HAECs, cells were incubated with FAK siRNA in HG group. The expression of EndMT-related markers (CD31 and FSP1), Ephrin B2 and FAK were detected by qRT-PCR and western blot.

Results

The results showed that HG significantly inhibited the expression of CD31 and increased FSP1 compared with NG group. Moreover, Ephrin B2 was increased after HG incubation. Ephrin B2 siRNA attenuated HG-induced expression of EndMT-related markers. Furthermore, HG increased the expression of FAK and phosphorylated FAK (pho-FAK) in HAECs. In contrast, blocking Ephrin B2 could partially attenuate HG-induced FAK activation. And FAK siRNA further inhibited the EndMT-related markers in HAECs treated with HG.

Conclusions

HG-induced EndMT in HAECs might be partially mediated by Ephrin B2 and the downstream FAK pathway.

Knockdown of LINC00657 inhibits ox-LDL-induced endothelial cell injury by regulating miR-30c-5p/Wnt7b/β-catenin

Long noncoding RNAs (lncRNAs) play pivotal roles in the pathogenesis, development, and treatment of atherosclerosis (AS). The endothelial cell injury is a feature of AS. However, the role and mechanism of lncRNA LINC00657 in oxidized low-density lipoprotein (ox-LDL)-induced endothelial cell injury remain unclear. The serum samples were collected from 32 AS patients and normal volunteers. Ox-LDL-treated human umbilical vein endothelial cells (HUVEC) were used for the experiments in vitro. The levels of LINC00657, microRNA (miR)-30c-5p and Wnt family member 7B (Wnt7b) were measured by quantitative real-time polymerase chain reaction or western blot. The expression levels of proteins in Wnt7b/β-catenin pathway or endothelial-mesenchymal transition (EndMT) were detected by western blot. The secretion of inflammatory cytokine was examined by enzyme linked immunosorbent assay (ELISA). Cell viability and apoptosis were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide, flow cytometry, and western blot. The target association of miR-30c-5p and LINC00657/Wnt7b was analyzed via dual-luciferase reporter assay and RNA pull-down assay. LINC00657 expression was increased in AS serum and ox-LDL-treated HUVEC cells. LINC00657 knockdown suppressed ox-LDL-induced Wnt7b/β-catenin activation, EndMT, inflammatory response, and apoptosis in HUVEC cells. MiR-30c-5p was bound to LINC00657 and it knockdown reversed the role of LINC00657 inhibition in ox-LDL-induced HUVEC cell injury. MiR-30c-5p targeted Wnt7b to inhibit ox-LDL-induced Wnt7b/β-catenin activation, EndMT, inflammatory response, and apoptosis in HUVEC cells. Silence of LINC00657 repressed ox-LDL-induced injury via inhibiting EndMT, inflammatory response, and apoptosis in HUVEC cells by regulating miR-30c-5p/Wnt7b/β-catenin, indicating a potential target for treatment of AS.

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.

HuangqiGuizhiWuwu Decoction Prevents Vascular Dysfunction in Diabetes via Inhibition of Endothelial Arginase 1

Hyperglycemia induces vascular endothelial dysfunction, which contributes to the development of vascular complication of diabetes. A classic prescription of traditional medicine, HuangqiGuizhiWuwu Decoction (HGWWD) has been used for the treatment of various cardiovascular and cerebrovascular diseases, which all are related with vascular pathology. The present study investigated the effect of HGWWD treatment in streptozocin (STZ)-induced vascular dysfunction in mouse models. In vivo studies were performed using wild type mice as well as arginase 1 knockout specific in endothelial cells (EC-A1-/-) of control mice, diabetes mice and diabetes mice treated with HGWWD (60 g crude drugs/kg/d) for 2 weeks. For in vitro studies, aortic tissues were treated with mice serum containing HGWWD with or without adenoviral arginase 1 (Ad-A1) transduction in high glucose (HG) medium. We found that HGWWD treatment restored STZ-induced impaired mean velocity and pulsatility index of mouse left femoral arteries, aortic pulse wave velocity and vascular endothelial relaxation accompanied by elevated NO production in the aorta and plasma, as well as reduced endothelial arginase activity and aortic arginase 1 expression. The protective effect of HGWWD is reversed by an inhibitor of nitric oxide synthesis. Meanwhile, the preventive effect of serum containing HGWWD in endothelial vascular dysfunction is completely blocked by Ad-A1 transduction in HG incubated aortas. HGWWD treatment further improved endothelial vascular dysfunction in STZ induced EC-A1-/- mice. This study demonstrates that HGWWD improved STZ-induced vascular dysfunction through arginase 1 - NO signaling, specifically targeting endothelial arginase 1.

Endothelial Aldehyde Dehydrogenase 2 as a Target to Maintain Vascular Wellness and Function in Ageing

Endothelial cells are the main determinants of vascular function, since their dysfunction in response to a series of cardiovascular risk factors is responsible for disease progression and further consequences. Endothelial dysfunction, if not resolved, further aggravates the oxidative status and vessel wall inflammation, thus igniting a vicious cycle. We have furthermore to consider the physiological manifestation of vascular dysfunction and chronic low-grade inflammation during ageing, also known as inflammageing. Based on these considerations, knowledge of the molecular mechanism(s) responsible for endothelial loss-of-function can be pivotal to identify novel targets of intervention with the aim of maintaining endothelial wellness and vessel trophism and function. In this review we have examined the role of the detoxifying enzyme aldehyde dehydrogenase 2 (ALDH2) in the maintenance of endothelial function. Its impairment indeed is associated with oxidative stress and ageing, and in the development of atherosclerosis and neurodegenerative diseases. Strategies to improve its expression and activity may be beneficial in these largely diffused disorders.

NAD+ repletion inhibits the endothelial-to-mesenchymal transition induced by TGF-β in endothelial cells through improving mitochondrial unfolded protein response

Endothelial-to-mesenchymal transition (EndMT) plays an important role in the progression of cardiac fibrosis but its mechanism and treatment need to be further understood. Herein, we have found that mitochondrial unfolded protein response (mtUPR) played a critical role in transforming growth factor beta 1 (TGF-β1)-induced EndMT in endothelial cells (ECs). MtUPR was repressed in endothelial cells after exposure to TGF-β1. NAD + precursor nicotinamide riboside (NR) could attenuate TGF-β1-induced EndMT and improve the levels of mtUPR. Significantly, prohibitin proteins (PHB and PHB2) was also regulated by nicotinamide riboside. Moreover, we found that inhibition of prohibitin proteins could prevent the protective effect of nicotinamide riboside on mtUPR and TGF-β1-induced EndMT. Overexpression of prohibitin proteins could alleviate mitochondrial function and TGF-β1-induced EndMT through improving mtUPR. In vivo, The EndMT of ECs induced by Transverse aortic constriction (TAC) in mouse was inhibited by NR. In conclusion, our results indicate that nicotinamide riboside improved the expression of prohibitin proteins to ameliorate EndMT via promotion of mtUPR. Nicotinamide riboside is a potential therapeutic target for cardiac fibrosis.