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Background & Aims: The pathophysiology of irritable bowel syndrome (IBS) is multifactorial and includes epithelial barrier dysfunction, a key element at the interface between the gut lumen and the deeper intestinal layers. Beneath the epithelial barrier there is the vascular one representing the last barrier to avoid luminal antigen dissemination The aims of this study were to correlate morpho-functional aspects of epithelial and vascular barriers with symptom perception in IBS., Methods: Seventy-eight healthy subjects (controls) and 223 patients with IBS were enrolled in the study and phenotyped according to validated questionnaires. Sugar test was used to evaluate in vivo permeability. Immunohistochemistry, western blot, and electron microscopy were used to characterize the vascular barrier. Vascular permeability was evaluated by assessing the mucosal expression of plasmalemma vesicle-associated protein-1 and vascular endothelial cadherin. Caco-2 or human umbilical vein endothelial cell monolayers were incubated with soluble mediators released by mucosal biopsies to highlight the mechanisms involved in permeability alteration. Correlation analyses have been performed among experimental and clinical data., Results: The intestinal epithelial barrier was compromised in patients with IBS throughout the gastrointestinal tract. IBS-soluble mediators increased Caco-2 permeability via a downregulation of tight junction gene expression. Blood vessel density and vascular permeability were increased in the IBS colonic mucosa. IBS mucosal mediators increased permeability in human umbilical vein endothelial cell monolayers through the activation of protease-activated receptor-2 and histone deacetylase 11, resulting in vascular endothelial cadherin downregulation. Permeability changes correlated with intestinal and behavioral symptoms and health-related quality of life of patients with IBS., Conclusions: Epithelial and vascular barriers are compromised in patients with IBS and contribute to clinical manifestations., (Copyright © 2024 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Protein S (PROS1) is a vitamin K-dependent anticoagulant factor, which also acts as an agonist for the TYRO3, AXL, and MERTK (TAM) tyrosine kinase receptors. PROS1 is produced by the endothelium which also expresses TAM receptors, but little is known about its effects on vascular function and permeability. Transwell permeability assays as well as Western blotting and immunostaining analysis were used to monitor the possible effects of PROS1 on both endothelial cell permeability and on the phosphorylation state of specific signaling proteins. We show that human PROS1, at its circulating concentrations, substantially increases both the basal and VEGFA-induced permeability of endothelial cell (EC) monolayers. PROS1 induces p38 MAPK (Mitogen Activated Protein Kinase), Rho/ROCK (Rho-associated protein kinase) pathway activation, and actin filament remodeling, as well as substantial changes in Vascular Endothelial Cadherin (VEC) distribution and its phosphorylation on Ser 665 and Tyr 685 . It also mediates c-Src and PAK-1 (p21-activated kinase 1) phosphorylation on Tyr 416 and Ser 144 , respectively. Exposure of EC to human PROS1 induces VEC internalization as well as its cleavage into a released fragment of 100 kDa and an intracellular fragment of 35 kDa. Using anti-TAM neutralizing antibodies, we demonstrate that PROS1-induced VEC and c-Src phosphorylation are mediated by both the MERTK and TYRO3 receptors but do not involve the AXL receptor. MERTK and TYRO3 receptors are also responsible for mediating PROS1-induced MLC (Myosin Light Chain) phosphorylation on a site targeted by the Rho/ROCK pathway. Our report provides evidence for the activation of the c-Src/VEC and Rho/ROCK/MLC pathways by PROS1 for the first time and points to a new role for PROS1 as an endogenous vascular permeabilizing factor., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Background: In the present study, we measured the serum vascular endothelial cadherin (VEC) and vinculin (Vcn) concentrations in patients with type B acute aortic dissection (TBAD) to evaluate their diagnostic value for this condition., Methods: A total of 100 patients with TBAD and 90 matched controls were included in the study. The serum concentrations of VEC and Vcn were measured using enzyme-linked immunosorbent assays., Results: The serum VEC and Vcn concentrations were significantly higher in participants with TBAD than in healthy controls. Compared with patients with acute myocardial infarction (AMI), the serum concentrations of VEC and Vcn in patients with TBAD were higher, and the Vcn showed significant difference, with statistical significance. Receiver operating characteristic analysis generated areas under the curves for VEC and Vcn that were diagnostic for TBAD (0.599 and 0.655, respectively). The optimal cut-off values were 3.975 ng/μL and 128.1 pg/mL, the sensitivities were 43.0% and 35.0%, and the specificities were 73.3% and 90.0%, respectively. In addition, the use of a combination of serum VEC and Vcn increased the AUC to 0.661, with a sensitivity of 33.0% and a specificity of 93.33%. A high serum Vcn concentration was associated with a higher risk of visceral malperfusion in participants with TBAD (odds ratio (OR) = 1.007, 95% confidence interval [CI]: 1.001-1.013, p = 0.014). In participants with refractory pain, the adjusted OR for the serum VEC concentration increased to 1.172 (95% CI: 1.010-1.361; p = 0.036), compared with participants without refractory pain., Conclusion: This study is the first to show the diagnostic value of serum VEC and Vcn for AAD and their relationships with the clinical characteristics of patients with TBAD. Thus, VEC and Vcn are potential serum markers of TBAD.

Vascular endothelial-cadherin (VE-cadherin), matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) have emerged as key-factors of atherogenesis. The aim of this study was to evaluate the effects of exercise training (ET) on those key-factors in relation to the progression of atherosclerotic lesions in hypercholesterolemic mice. Thirty male, apoE knockout (apoE -/- ) mice were randomly assigned to the following equivalent groups: 1) CO-control: High-fat diet (HFD) administration for 12 weeks. 2) EX-exercise: HFD administration as in CO, and during the last 4 weeks (9th -12th week) ET on treadmill (5sessions/week, 60min/session). At the end of study, blood samples were obtained and all mice were sacrificed. Aortic roots were excised and analysed regarding the percentage of aortic stenosis, and the relative concentrations of collagen, elastin, VE-cadherin, MMP-8,-9 and TIMP-1,-2 within the atherosclerotic lesions. Aortic stenosis was significantly lower in the EX than the CO group (39.63 ± 7.22% vs 62.04 ± 8.55%; p < 0.001), along with considerable increase in fibrous cap thickness and of collagen and elastin contents within plaques (p < 0.05). Compared to controls, exercised-treated mice showed reduced intra-plaque relative concentrations of VE-cadherin (15.09 ± 1.89% vs 23.49 ± 3.01%, p < 0.001), MMP-8 (8.51 ± 2.24% vs 18.51 ± 4.08%, p < 0.001) and MMP-9 (12.1 ± 4.86% vs 18.88 ± 6.23%, p < 0.001). Inversely, the relative concentrations of TIMP-1 and TIMP-2 in the ET group were considerably higher by 62.5% and 31.2% than in the EX group (p < 0.05), respectively. Finally, body weight and lipids concentrations did not differ between groups at the end of the study (p > 0.05). ET treatment induced regression of established atherosclerotic lesions in apoE -/- mice and improved their stability. Those effects seemed to be mediated by favourable modification of VE-cadherin, MMPs and TIMPs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Vascular endothelium is a target of cadmium (Cd), which is a global pollutant of the environment. However, the detailed effects and underlying mechanisms remain to be elucidated. In the present study, human umbilical vein endothelial cells (HUVECs) were treated with 0.1, 1, 5, 10, 50 µM cadmium chloride (CdCl 2 ) for 12 h. It was found that vascular endothelial (VE)-cadherin mRNA and protein expression was upregulated by Cd in HUVECs in a dose-dependent manner. Higher levels of VE-cadherin were detected at cell-to-cell junctions in HUVECs treated with 10 µM CdCl 2 compared with normal condition. The phosphorylation level of myosin-binding subunit of myosin phosphatase, a downstream substrate of Rho-associated protein kinase (ROCK), was reduced by 10 µM CdCl 2 , suggesting that Cd inhibited the Rho/ROCK pathway. Activation of ROCK by narciclasine reversed the Cd-induced increase of VE-cadherin expression. By contrast, ROCK pathway inhibitor Y27632 increased VE-cadherin expression in HUVECs. Following inhibition of the ROCK pathway, Cd did not significantly alter the level of VE-cadherin. Taken together, the results suggested that Cd exposure enhanced VE-cadherin expression in endothelial cells via suppression of ROCK signaling., Competing Interests: The authors declare that they have no competing interests., (Copyright © 2020, Spandidos Publications.)

The aim of the present study was to investigate the protective effect of dexmedetomidine (Dex) on endothelial injury in a cecal ligation and puncture (CLP)-induced rat model of sepsis. A total of 36 male Sprague-Dawley rats were divided into three groups: Sham, CLP and CLP + Dex. The wet/dry (W/D) ratio of lung weight, hematoxylin and eosin (H&E) staining of lung tissue, plasma levels of angiopoietin (Ang)1 and 2, ratio of Ang2/1 and vascular endothelial (VE)-cadherin protein expression levels in lung tissue were determined. The W/D ratio of lung tissue in the CLP + Dex group was significantly lower than that in the CLP group (P<0.01). The H&E staining results indicated that Dex treatment reduced the levels of CLP-induced alveolar septum widening, infiltrating white blood cells and congestion, when compared with CLP alone. In addition, the expression levels of plasma Ang2 and the Ang2/1 ratio in the CLP + Dex group were significantly lower than those of the CLP rats (P<0.01). Furthermore, the level of VE-cadherin protein in lung tissue of the CLP + Dex group was higher than that of the CLP group (P<0.05). The results indicated that Dex had a protective effect against CLP-induced endothelial injury, through the ability to reduce expression of the endothelial injury factor Ang2 and increase the expression of the endothelial adhesion junction factor VE-cadherin in a septic rat model. These data suggest a potential application of Dex in the clinical treatment of sepsis., (Copyright: © Zhang et al.)

Background: Vascular permeability (VP) is a fundamental aspect of vascular biology. A growing number of studies have revealed that many signalling pathways govern VP in both physiological and pathophysiological conditions. Furthermore, emerging evidence identifies VP alteration as a pivotal pathogenic factor in acute kidney injury, chronic kidney disease, diabetic kidney disease, and other proteinuric diseases. Therefore, perceiving the connections between these pathways and the aetiology of kidney disease is an important task as such knowledge may trigger the development of novel therapeutic or preventive medical approaches. In this regard, the discussion summarizing VP-regulating pathways and associating them with kidney diseases is highly warranted., Summary: Major pathways of VP regulation comprise angiogenic factors including vascular endothelial growth factor/VEGFR, angiopoietin/Tie, and class 3 semaphorin/neuropilin and inflammatory factors including histamine, platelet-activating factor, and leukocyte extravasation. These pathways mainly act on vascular endothelial cadherin to modulate adherens junctions of endothelial cells (ECs), thereby augmenting VP via the paracellular pathway. Elevated VP in diverse kidney diseases involves EC apoptosis, imbalanced regulatory factors, and many other pathophysiological events, which in turn exacerbates renal structural and functional disorders. Measures improving VP effectively ameliorate the diseased kidney in terms of tissue injury, endothelial dysfunction, kidney function, and long-term prognosis. Key Messages: (1) Angiogenic factors, inflammatory factors, and adhesion molecules represent major pathways that regulate VP. (2) Vascular hyperpermeability links various pathophysiological processes and plays detrimental roles in multiple kidney diseases., (© 2021 S. Karger AG, Basel.)

Background: Lung ischemia reperfusion injury (LIRI) is a complex pathophysiological process activated by lung transplantation and acute lung injury. The p38 mitogen-activated protein kinase (MAPK) is involved in breakdown of the endothelial barrier during LIRI, but the mechanism is still unclear. Therefore, we investigated the function of p38 MAPK in LIRI in vivo and in vitro . Methods: Sprague-Dawley rats were subjected to ischemia reperfusion with or without pretreatment with a p38 MAPK inhibitor. Lung injury was assessed using hematoxylin and eosin staining, and pulmonary blood-air barrier permeability was evaluated using Evans blue staining. A rat pulmonary microvascular endothelial cell line was infected with lentiviral expressing short hairpin (sh)RNA targeting p38 MAPK and then cells were subjected to oxygen/glucose deprivation and reoxygenation (OGD/R). Markers of endothelial destruction were measured by western blot and immunofluorescence. Results: In vivo LIRI models showed structural changes indicative of lung injury and hyperpermeability of the blood-air barrier. Inhibiting p38 MAPK mitigated these effects. Oxygen/glucose deprivation and reoxygenation promoted hyperpermeability of the endothelial barrier in vitro , but knockdown of p38 MAPK attenuated cell injury; maintained endothelial barrier integrity; and partially reversed injury-induced downregulation of permeability protein AQP1, endothelial protective protein eNOS, and junction proteins ZO-1 and VE-cadherin while downregulating ICAM-1, a protein involved in destroying the endothelial barrier, and ET-1, a protein involved in endothelial dysfunction. Conclusion: Inhibition of p38 MAPK alleviates LIRI by decreasing blood-air hyperpermeability. Blocking p38 MAPK may be an effective treatment against acute lung injury., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2020 Wang, Pan, Liu, Li, Lin, He, Xiao, Li and Lin.)

Atherosclerosis is associated with a compromised endothelial barrier, facilitating the accumulation of immune cells and macromolecules in atherosclerotic lesions. In this study, we investigate endothelial barrier integrity and the enhanced permeability and retention (EPR) effect during atherosclerosis progression and therapy in Apoe -/- mice using hyaluronan nanoparticles (HA-NPs). Utilizing ultrastructural and en face plaque imaging, we uncover a significantly decreased junction continuity in the atherosclerotic plaque-covering endothelium compared to the normal vessel wall, indicative of disrupted endothelial barrier. Intriguingly, the plaque advancement had a positive effect on junction stabilization, which correlated with a 3-fold lower accumulation of in vivo administrated HA-NPs in advanced plaques compared to early counterparts. Furthermore, by using super-resolution and correlative light and electron microscopy, we trace nanoparticles in the plaque microenvironment. We find nanoparticle-enriched endothelial junctions, containing 75% of detected HA-NPs, and a high HA-NP accumulation in the endothelium-underlying extracellular matrix, which suggest an endothelial junctional traffic of HA-NPs to the plague. Finally, we probe the EPR effect by HA-NPs in the context of metabolic therapy with a glycolysis inhibitor, 3PO, proposed as a vascular normalizing strategy. The observed trend of attenuated HA-NP uptake in aortas of 3PO-treated mice coincides with the endothelial silencing activity of 3PO, demonstrated in vitro. Interestingly, the therapy also reduced the plaque inflammatory burden, while activating macrophage metabolism. Our findings shed light on natural limitations of nanoparticle accumulation in atherosclerotic plaques and provide mechanistic insight into nanoparticle trafficking across the atherosclerotic endothelium. Furthermore, our data contribute to the rising field of endothelial barrier modulation in atherosclerosis.

Background: Vasculogenic mimicry (VM) plays an important role in invasion and metastasis of malignant tumor. High expression of vascular endothelial cadherin (VE-cahderin) in malignant tumor cells can promote the formation of VM. High expression of SOX4 (sex-determining region Y-related high-mobility group box 4) was found in esophageal squamous cell carcinoma (ESCC). It can promote the development of epithelial stromal transformation. Then, SOX4 can promote the formation of VM in ESCC., Methods: Paraffin-embedded specimens of ESCC (with complete clinicopathological data) and normal esophageal mucosa adjacent to carcinoma (> 5 cm) were collected from January to December 2013. CD34/PAS was used to detect VM. The expression of VE-cadherin and SOX4 was used by immunohistochemistry. The patients were followed up in detail (survival time and survival status)., Results: SOX4, VM, and VE-cadherin were highly expressed in ESCC. Moreover, they were positively correlated. Survival analysis shows that the expressions of SOX4, VM, and VE-cadherin are associated with the patient's prognosis and can be independent prognostic factors for ESCC., Conclusions: Studies suggests that SOX4, which is highly expressed in ESCC, is involved in the formation of VM. The combined detection of SOX4, VE-cadherin and VM expression can be used as biomarkers for invasion and metastasis of ESCC. These three markers can be used as powerful prognostic factors in patients with ESCC., Competing Interests: None., (IJCEP Copyright © 2019.)

Objective: The objective of our study was to determine levels of endothelial progenitor cells (EPCs) in preeclampsia and normotensive pregnant women., Study Design: Prospective cohort study of women with preeclampsia and normotensive pregnancies. EPCs were estimated by flow cytometry. Multiple linear regression was used to assess the association of EPCs with preeclampsia adjusting for maternal age, body mass index (BMI), gestation and ethnicity., Main Outcome Measure: Levels of EPCs in preeclampsia and normotensive pregnancies, with CD-34 and vascular endothelial (VE)-cadherin as markers of EPCs. VE-cadherin is an endothelial cell adhesion molecule used to delineate endothelial lineage of EPCs., Results: There were thirty women in the preeclampsia group and thirty-three in the normotensive group. The two groups were similar except for the BMI and blood pressures, which were higher in preeclampsia. On multiple linear regression, EPCs numbers were significantly higher by 29 (95% confidence interval 11.7-46.6, p = 0.001) in preeclampsia compared to the normotensive group. There was significant positive correlation between EPCs and systolic blood pressure in preeclampsia (Spearman correlation coefficient 0.39, p = 0.03)., Conclusion: Although widely used in cardiovascular disease other than preeclampsia, this is the first study using VE-cadherin as a marker of endothelial lineage to define EPCs in preeclampsia. Our results suggest the higher number of EPCs in preeclampsia may be a response of the bone marrow to endothelial injury., (Copyright © 2019 International Society for the Study of Hypertension in Pregnancy. Published by Elsevier B.V. All rights reserved.)

Objective: The blood-brain barrier (BBB) of patients with moyamoya angiopathy (MMA) is unstable, which may contribute to transient neurologic symptoms (TNS) after direct bypass surgery. However, BBB-related proteins have never been investigated. The purpose of this study was to evaluate the perioperative serum levels of biomarkers representing BBB function in MMA patients based on the hypothesis that postoperative hemodynamic change may disrupt the BBB., Methods: A total of 12 hemispheres in 11 patients with MMA were prospectively examined. Direct revascularization surgery was performed for all cases. The serum levels of tight junction (occludin and claudin 5), adherens junction (vascular endothelial-cadherin) proteins, and matrix metalloproteinase (MMP)-2 and MMP-9 were measured quantitatively 1 day before surgery and on postoperative days 1, 4, and 7., Results: Successful patency of the direct bypass was achieved in all. The serum level of occludin was significantly increased on postoperative day 1, and the levels in 2 cases with TNS were markedly elevated over 10-fold higher than baseline. Furthermore, the postoperative MMP-9 levels were significantly elevated on each day. On the other hand, there was no significant fluctuation in claudin 5, vascular endothelial-cadherin, and MMP-2 level., Conclusions: Marked changes in biomarkers representing the tight junction of the BBB were observed. These preliminary results suggest that marked hemodynamic change and TNS in some patients are associated with disruption of the BBB after direct bypass surgery for MMA., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Per- and polyfluoroalkyl substances (PFASs) are ubiquitous and high persistent in human blood, thus potentially inducing a myriad of deleterious consequences. Plasma kallikrein-kinin system (KKS), which physiologically regulates vascular permeability, is vulnerable to exogenous stimulators, like PFASs with long-chain alkyl backbone substituted by electronegative fluorine. The study on the interactions of PFASs with the KKS and the subsequent effects on vascular permeability would be helpful to illustrate how the chemicals penetrate the biological vascular barriers to reach different tissues. In present study, three representative PFASs, including perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and perfluorohexadecanoic acid (PFHxDA), were investigated for their effects on the activation of the KKS, paracellular permeability in human retina endothelial cells (HRECs) and integrity of the adherens junctions. In contrast to either PFOS or PFOA, PFHxDA efficiently triggered KKS activation in a concentration-dependent manner based on protease activity assays. The plasma activated by PFHxDA significantly increased paracellular permeability of HRECs through the degradation of adherens junctions. As evidenced by the antagonistic effect of aprotinin, PFHxDA-involved effects on vascular permeability were mediated by KKS activation. The results herein firstly revealed the mechanistic pathway for PFHxDA induced effects on vascular endothelial cells. Regarding the possible structure-related activities of the chemicals, this finding would be of great help in the risk assessment of PFASs., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Dense monolayers of living cells display intriguing relaxation dynamics, reminiscent of soft and glassy materials close to the jamming transition, and migrate collectively when space is available, as in wound healing or in cancer invasion. Here we show that collective cell migration occurs in bursts that are similar to those recorded in the propagation of cracks, fluid fronts in porous media, and ferromagnetic domain walls. In analogy with these systems, the distribution of activity bursts displays scaling laws that are universal in different cell types and for cells moving on different substrates. The main features of the invasion dynamics are quantitatively captured by a model of interacting active particles moving in a disordered landscape. Our results illustrate that collective motion of living cells is analogous to the corresponding dynamics in driven, but inanimate, systems., Competing Interests: The authors declare no conflict of interest.

The generation of a confluent and functional endothelium at the luminal surface of cardiovascular devices represents the ideal solution to avoid contact between blood and synthetic materials thus allowing the long-term body integration of the implants. Due to the foreseen paucity of source cells in cardiovascular patients, surface engineering strategies to achieve full endothelialization, while minimizing the amount of endothelial cells required to seed the surface leading to prompt and full coverage with an endothelium are necessary. A stable endothelialization is the result of the interplay between endothelial cells, the flow-generated walls shear stress and the substrate topography. Here a novel strategy is designed and validated based on the use of engineered surface textures combined with confined islands of seeded endothelial cells. Upon release of the confinement, the cell island populations are able to migrate on the texture and merge under physiological flow conditions to promptly generate a fully connected endothelium. The interaction between endothelial cells and surface textures supports the process of endothelialization through the stabilization of cell-to-substrate adhesions and cell-to-cell junctions. It is shown that with this approach, when ≈50% of a textured surface is initially covered with cell seeding, the time to full endothelialization compared to an untextured surface is almost halved, underpinning the viability and effectiveness of the method for the quick and stable coverage of cardiovascular implants., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Aim: To explore the effects and mechanism of vascular endothelial cadherin (VE-cadherin) on experimental corneal neovascularization (CRNV)., Methods: Mouse corneas were burned with sodium hydroxide to build a CRNV model. The burned corneas were locally administrated with anti-mouse VE-cadherin neutralizing antibody. Annexin V and cluster of differentiation 31 (CD31) double staining was used to measure vascular endothelial cell apoptosis with the use of flow cytometry (FCM). The protein expression of NADPH oxidase 2 (Nox2), caspase-3, and protein kinase C (PKC) in the burned corneas were examined by Western blot. Human retinal endothelial cell (HREC) proliferation was detected using a Cell Counting Kit 8 (CCK-8) assay in vitro., Results: The amount of CRNV peaked two weeks after the alkali burn. FCM confirmed that VE-cadherin neutralizing antibody treatment increased CD31 positive cell apoptosis. Western blot revealed that the intracorneal protein expression of Nox2 and caspase-3 were up-regulated, while PKC was down-regulated in the VE-cadherin neutralizing antibody administrated group. CCK-8 assay showed that VE-cadherin neutralizing antibody markedly inhibited HREC proliferation., Conclusion: VE-cadherin exhibited an anti-apoptosis effect through enhanced PKC signaling and an enhanced cell proliferation pathway.

Tyrosine kinase receptor B (TrkB) is a high-affinity receptor for brain-derived neurotrophic factor (BDNF). In addition to its nervous system functions, TrkB is also expressed in the aortic endothelium. However, the effects of endothelial TrkB signaling on atherosclerosis remained unknown. Immunofluorescence analysis revealed that TrkB expression is downregulated in the endothelium of atherosclerotic lesions from ApoE-/- mice compared with the atheroma-free aorta of WT mice. Endothelial TrkB knockdown led to increased lesion size, lipid deposition and inflammatory responses in the atherosclerotic lesions of the ApoE-/- mice compared with the control mice. Mechanistic studies showed that TrkB activation prevented VE-cadherin shedding by enhancing the interaction between vascular endothelial protein tyrosine phosphatase and VE-cadherin, maintaining VE-cadherin in a dephosphorylated state. Our data demonstrate that TrkB is an endothelial injury-response molecule in atherogenesis. Endothelial BDNF/TrkB signaling reduces VE-cadherin shedding and protects against atherosclerotic lesion development in ApoE-/- mice.

Endothelial barrier restoration reverses microvessel hyperpermeability and facilitates recovery from lung injury. Because inhibiting connexin 43 (Cx43)-dependent interendothelial communication blunts hyperpermeability in single microvessels, we determined whether endothelial Cx43 levels correlate with changes in microvessel permeability during recovery from lung injury. Toward this, bacterial endotoxin was instilled intratracheally into rat lungs, and at different durations postinstillation the lungs were isolated and blood perfused. Microvessel Cx43 expression was quantified by in situ immunofluorescence and microvessel permeability via a fluorescence method. To supplement the immunofluorescence data, protein levels were determined by immunoblots of lung tissue from endotoxin-instilled rats. Immunofluorescence and immunoblot together revealed that both Cx43 expression and microvessel permeability increased above baseline within a few hours after endotoxin instillation but declined progressively over the next few days. On day 5 postendotoxin, microvessel Cx43 declined to negligible levels, resulting in complete absence of intermicrovessel communication determined by photolytic uncaging of Ca(2+). However, by day 14, both Cx43 expression and microvessel permeability returned to baseline levels. In contrast to Cx43, expression of microvessel vascular endothelial (VE)-cadherin, a critical determinant of vascular barrier integrity, exhibited an inverse trend by initially declining below baseline and then returning to baseline at a longer duration. Knockdown of vascular Cx43 by tail vein injection of Cx43 shRNA increased VE-cadherin expression, suggesting that reduction in Cx43 levels may modulate VE-cadherin levels in lung microvessels. Together, the data suggest that endotoxin challenge initiates interrelated changes in microvessel Cx43, VE-cadherin, and microvessel permeability, with changes in Cx43 temporally leading the other responses., (Copyright © 2015 the American Physiological Society.)

Vascular endothelial cadherin and β-catenin play a key role in establishment and maintenance of the endothelial monolayer integrity, regulation of vascular barrier function, and initiation of angiogenesis. The cadherin-catenin complex has been shown to be reduced in type 1 diabetic placenta, but the exact relationship between histopathologic findings and clinical data is not known. Immunohistochemistry of placental tissue from type 1, type 2, and gestational diabetes showed that diabetes per se might be compatible with normal levels of vascular endothelial (VE)-cadherin and β-catenin in fetoplacental vessels as long as the patient has not been treated with insulin. Immunoreactivity of VE-cadherin did correlate poorly with maternal glycemic control, as was investigated in this study, by birth weight, body mass index, and hemoglobin A1c (HbA1c). There was no correlation found between the immunoreactivity of β-catenin and birth weight, body mass index, or HbA1c. However our data did show a strong correlation between immunoreactivity and whether or not the patient had been treated with insulin. Patients diagnosed with gestational diabetes who had not been treated with insulin had similar levels of VE-cadherin and β-catenin to the control group, thus indicating that diabetes per se must not necessarily lead to a reduction. Our study suggests that therapeutic intervention using insulin in pregnancies complicated by diabetes might have potentially harmful effects on placental morphology. Future studies should further investigate these findings.

Interaction between platelets and artificial materials within cardiovascular devices triggers blood coagulation and represents a frequent adverse response to implant deployment. Avoidance of this interaction is obtained through the generation and sustenance under flow of a confluent and stable endothelial monolayer covering the luminal device surface, altogether defined as the process of endothelialization. Supraphysiological wall shear stress (WSS) levels generated within vascular assist devices (VADs) constitute a major challenge toward endothelialization. Here we report the experimental demonstration that stable endothelialization can be achieved at supraphysiological WSS levels by pure means of appropriate surface micro-structuring. Using a custom-designed flow bioreactor we exposed endothelial monolayers to physiological and supraphysiological WSS levels and investigated the resulting integrity of cell-to-cell junctions, the cell density and the cell polarization. At physiological WSS levels, optimal endothelialization was obtained independently from surface topography. However, at higher WSS levels, only monolayers grown on appropriately micro-structured surfaces preserved optimal integrity. Under these flow conditions, endothelial cells polarized by the contact with the micro-structure and, interestingly, oriented themselves in the direction perpendicular to flow. Such endothelial layers withstood WSS levels exceeding of 100% or more the thresholds detected on flat substrates., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Background: Vascular endothelial growth factors (VEGFs) are potential therapeutic agents for treatment of ischemic diseases. Their angiogenic effects are mainly mediated through VEGF receptor 2 (VEGFR2)., Methods: Receptor binding, signaling, and biological efficacy of several VEGFR2 ligands were compared to determine their characteristics regarding angiogenic activity and vascular permeability., Results: Tested VEGFR2 ligands induced receptor tyrosine phosphorylation with different efficacy depending on their binding affinities. However, the tyrosine phosphorylation pattern and the activation of the major downstream signaling pathways were comparable. The maximal angiogenic effect stimulated by different VEGFR2 ligands was dependent on their ability to bind to co-receptor Neuropilin (Nrp), which was shown to form complexes with VEGFR2. The ability of these VEGFR2 ligands to induce vascular permeability was dependent on their concentration and VEGFR2 affinity, but not on Nrp binding., Conclusions: VEGFR2 activation alone is sufficient for inducing endothelial cell proliferation, formation of tube-like structures and vascular permeability. The level of VEGFR2 activation is dependent on the binding properties of the ligand used. However, closely similar activation pattern of the receptor kinase domain is seen with all VEGFR2 ligands. Nrp binding strengthens the angiogenic potency without increasing vascular permeability., General Significance: This study sheds light on how different structurally closely related VEGFR2 ligands bind to and signal via VEGFR2/Nrp complex to induce angiogenesis and vascular permeability. The knowledge of this study could be used for designing VEGFR2/Nrp ligands with improved therapeutic properties., (© 2013.)

Notch signaling is an evolutionarily conserved pathway involved in cell fate control during development, stem cell self-renewal and postnatal tissue differentiation. Roles for Notch in carcinogenesis, in the biology of cancer stem cells, tumor angiogenesis and epithelial-to-mesenchymal transition (EMT) have been reported. This mini-review describes the role of Notch signaling deregulation in EMT and tumor aggressiveness. We describe how accumulated evidence suggests that Notch inhibition is an attractive strategy for the treatment of several cancers, at least in part because of its potential to reverse or prevent EMT., (Published by Elsevier Ireland Ltd.)

Blood levels of triglyceride-rich lipoproteins (TRL) increase postprandially, and a delay in their clearance results in postprandial hyperlipidemia, an important risk factor in atherosclerosis development. Atherosclerosis is a multifactorial inflammatory disease, and its initiation involves endothelial dysfunction, invasion of the artery wall by leukocytes and subsequent formation of foam cells. TRL are implicated in several of these inflammatory processes, including the formation of damaging free radicals, leukocyte activation, endothelial dysfunction and foam cell formation. Recent studies have provided insights into the mechanisms of uptake and the signal transduction pathways mediating the interactions of TRL with leukocytes and vascular cells, and how they are modified by dietary lipids. Multiple receptor and non-receptor mediated pathways function in macrophage uptake of TRL. TRL also induce expression of adhesion molecules, cyclooxygenase-2 and heme-oxygenase-1 in endothelial cells, and activate intracellular signaling pathways involving mitogen-activated protein kinases, NF-κB and Nrf2. Many of these effects are strongly influenced by dietary components carried in TRL. There is extensive evidence indicating that raised postprandial TRL levels are a risk factor for atherosclerosis, but the molecular mechanisms involved are only now becoming appreciated. Here, we review current understanding of the mechanisms by which TRL influence vascular cell function., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Elevated permeability of retinal endothelial cells (REC), as observed in diabetic retinopathy (DR), is induced by extended exposure to ≥25 ng/ml vascular endothelial growth factor A165 (VEGF165) for up to 3 d and this effect is more pronounced when equimolar amounts of basic fibroblast growth factor (bFGF) and insulin-like growth factor (IGF-1) are present. Down-regulation of the tight-junction protein claudin-1 and its loss from the plasma membrane is associated with induced higher permeability, whereas other tight-junction proteins (e.g. claudin-3, claudin-5, ZO-1) show only subtle changes in our experimental setting. Using immortalized bovine REC (iBREC) as a well-established model, we investigated effects of other members of the VEGF family, i.e. VEGF121, placental growth factor (PlGF-1 and PlGF-2) and viral VEGF-E which activate different sets of VEGF receptors, on barrier function after extended treatment: iBREC were incubated with 1-100 ng/ml of the growth factors for up to 2 days before barrier function was assessed by measuring transendothelial resistance (TER). Presence of TJ-proteins was determined by western blot analyses and immunofluorescence staining. Similar experiments were performed to evaluate whether the primary actions of PlGF-1, PlGF-2 or VEGF121 are modulated by bFGF or IGF-1 when all growth factors (each at 25 ng/ml, but 10 ng/ml IGF-1) act simultaneously at equimolar concentrations. We also studied the potential normalization of the barrier disturbed with combinations of growth factors by addition of the VEGF-specific Fab fragment ranibizumab or the recombinant protein aflibercept which binds VEGF and PlGF. Whereas 1 ng/ml VEGF-E were sufficient to impair the iBREC barrier, a higher concentration of 100 ng/ml VEGF121 was needed to reduce TER and expression of claudin-1 over 2 days. By PlGF-1 or PlGF-2, the barrier was not affected even at the highest concentration tested (100 ng/ml) and these factors also did not modulate the effect of VEGF165. The weak barrier derangement caused by VEGF121 was slightly enhanced by bFGF and IGF-1. After induction of the barrier breakdown with various combinations of all growth factors included in the study, normal TER and claudin-1 expression was re-established by ranibizumab. Both VEGF inhibitors ranibizumab and aflibercept similarly reinstated lost claudin-1, even when applied at a small fraction of the clinically relevant concentrations. These results show that VEGF-A, but not PlGF impairs the barrier function of iBREC and that the longer isoform VEGF165 is more potent than VEGF121. To induce barrier dysfunction in iBREC, activation of VEGF receptor 2 - probably in concert with neuropilin-1 - seems to be sufficient because VEGF-E and VEGF165, but not PlGF-1/-2 reduced TER or claudin-1 expression., (Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.)