Increase In Microvascular Permeability Research Articles

Capturing effects of blood flow on the transplanted decellularized nephron with intravital microscopy

Organ decellularization creates cell-free, collagen-based extracellular matrices that can be used as scaffolds for tissue engineering applications. This technique has recently gained much attention, yet adequate scaffold repopulation and implantation remain a challenge. Specifically, there still needs to be a greater understanding of scaffold responses post-transplantation and ways we can improve scaffold durability to withstand the in vivo environment. Recent studies have outlined vascular events that limit organ decellularization/recellularization scaffold viability for long-term transplantation. However, these insights have relied on in vitro/in vivo approaches that need enhanced spatial and temporal resolutions to investigate such issues at the microvascular level. This study uses intravital microscopy to gain instant feedback on their structure, function, and deformation dynamics. Thus, the objective of this study was to capture the effects of in vivo blood flow on the decellularized glomerulus, peritubular capillaries, and tubules after autologous and allogeneic orthotopic transplantation into rats. Large molecular weight dextran molecules labeled the vasculature. They revealed substantial degrees of translocation from glomerular and peritubular capillary tracks to the decellularized tubular epithelium and lumen as early as 12 h after transplantation, providing real-time evidence of the increases in microvascular permeability. Macromolecular extravasation persisted for a week, during which the decellularized microarchitecture was significantly and comparably compromised and thrombosed in both autologous and allogeneic approaches. These results indicate that in vivo multiphoton microscopy is a powerful approach for studying scaffold viability and identifying ways to promote scaffold longevity and vasculogenesis in bioartificial organs.

ALDH2 attenuates LPS-induced increase of brain microvascular endothelial cell permeability by promoting fusion and inhibiting fission of the mitochondria

To investigate the effect of aldehyde dehydrogenase 2 (ALDH2) on lipopolysaccharide (LPS)- induced damage of mouse brain microvascular endothelial barrier and explore the role of mitochondrial fusion and fission in maintaining the integrity of endothelial barrier. Mouse brain microvascular endothelial cells were treated with 1 μg/ mL LPS for 24 h with or without pretreatment with 20 μmol/mL Alda-1 (a ALDH2 agonist) for 1 h. The changes in cell viability were assessed using cell counting Kit-8 (CCK8) assay, and the cell permeability was evaluated using transendothelial cell resistance (TEER) and FITC-Dextran assay. The level of oxidative stress in the cells was assessed by detecting the levels of malondialdehyde (MDA) and superoxide dismutase (SOD), and the content of reactive oxygen species (ROS) was detected using a superoxide anion fluorescent probe (DHE). Western blotting was performed to detect the expressions of ALDH2, tight junction proteins ZO-1 and occludin, and mitochondrial fusion- and division-related proteins Mfn2, OPA1, Drp1 and Fis1. Compared with the untreated cells, the cells treated with LPS showed significantly decreased TEER, increased FITC-dextran leakage, MDA content and ROS production, decreased SOD activity expressions of ALDH2, ZO-1, occludin, Mfn2 and OPA1, and increased expressions of Drp1 and Fis1 (P < 0.05). Pretreatment with Alda-1 prior to LPS exposure strongly suppressed the increase of endothelial cell membrane permeability, reduced ROS production, increased the expressions of ALDH2, ZO-1, occludin, OPA1 and Mfn2, and lowered the expressions of Drp1 and Fis1 (P < 0.05). ALDH2 can alleviate LPS-induced damage of brain microvascular endothelial cell barrier by inhibiting the mitochondrial ROS production and promoting mitochondrial fusion and inhibiting mitochondrial fission.

Omentum-on-a-chip: A multicellular, vascularized microfluidic model of the human peritoneum for the study of ovarian cancer metastases

Epithelial ovarian cancer has the highest mortality rate of any gynecologic malignancy and most frequently metastasizes to the peritoneal cavity. Intraperitoneal metastases are highly associated with ascites, the pathologic accumulation of peritoneal fluid due to impaired drainage, increased peritoneal permeability, and tumor and stromal cytokine secretion. However, the relationship between ascites, vascular and mesothelial permeability, and ovarian cancer intraperitoneal metastases remains poorly understood. In this study, a vascularized in vitro model of the human peritoneal omentum and ovarian tumor microenvironment (TME) was employed to study stromal cell effects on tumor cell (TC) attachment and growth, as well as TC effects on vascular and mesothelial permeability in models of both early- and late-stage metastases. Control over the number of TCs seeded in the vascularized peritoneum revealed a critical cell density requirement for tumor growth, which was further enhanced by stromal adipocytes and endothelial cells found in the peritoneal omentum. This tumor growth resulted in both a physically-mediated decrease and cytokine-mediated increase in microvascular permeability, emphasizing the important and potentially opposing roles of tumor cells in ascites formation. This system provides a robust platform to elucidate TC-stromal cell interactions during intraperitoneal metastasis of ovarian cancer and presents the first in vitro vascularized model of the human peritoneum and ovarian cancer TME.

Redox Regulation of Microvascular Permeability: IL-1β Potentiation of Bradykinin-Induced Permeability Is Prevented by Simvastatin.

Antioxidant effects of statins have been implicated in the reduction in microvascular permeability and edema formation in experimental and clinical studies. Bradykinin (Bk)-induced increases in microvascular permeability are potentiated by IL-1β; however, no studies have examined the protection afforded by statins against microvascular hyperpermeability. We investigated the effects of simvastatin pretreatment on albumin–fluorescein isothiocyanate conjugate (FITC-albumin) permeability in post-capillary venules in rat cremaster muscle. Inhibition of nitric oxide synthase with L-NAME (10µM) increased basal permeability to FITC-albumin, which was abrogated by superoxide dismutase and catalase. Histamine-induced (1 µM) permeability was blocked by L-NAME but unaffected by scavenging reactive oxygen species with superoxide dismutase (SOD) and catalase. In contrast, bradykinin-induced (1–100 nM) permeability increases were unaffected by L-NAME but abrogated by SOD and catalase. Acute superfusion of the cremaster muscle with IL-1β (30 pM, 10 min) resulted in a leftward shift of the bradykinin concentration–response curve. Potentiation by IL-1β of bradykinin-induced microvascular permeability was prevented by the nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) inhibitor apocynin (1 µM). Pretreatment of rats with simvastatin (5 mg·kg−1, i.p.) 24 h before permeability measurements prevented the potentiation of bradykinin permeability responses by IL-1β, which was not reversed by inhibition of heme oxygenase-1 with tin protoporphyrin IX (SnPP). This study highlights a novel mechanism by which simvastatin prevents the potentiation of bradykinin-induced permeability by IL-1β, possibly by targeting the assembly of NADPH oxidase subunits. Our findings highlight the therapeutic potential of statins in the prevention and treatment of patients predisposed to inflammatory diseases.

Anisodamine Hydrobromide Protects Glycocalyx and Against the Lipopolysaccharide-Induced Increases in Microvascular Endothelial Layer Permeability and Nitric Oxide Production.

Anisodamine hydrobromide (Ani HBr) has been used to improve the microcirculation during cardiovascular disorders and sepsis. Glycocalyx plays an important role in preserving the endothelial cell (EC) barrier permeability and nitric oxide (NO) production. We aimed to test the hypothesis that Ani HBr could protect the EC against permeability and NO production via preventing glycocalyx shedding. A human cerebral microvascular EC hCMEC/D3 injury model induced by lipopolysaccharide (LPS) was established. Ani HBr was administrated to ECs with the LPS challenge. Cell viability was performed by Cell Counting Kit-8 assay. Cell proliferation and apoptosis were detected by EdU and Hoechst 33342 staining. Apoptosis and cell cycle were also assessed by flow cytometry with annexin V staining and propidium iodide staining, respectively. Then, adherens junction integrity was evaluated basing on the immunofluorescence staining of vascular endothelial cadherin (VE-cadherin). The glycocalyx component heparan sulfate (HS) was stained in ECs. The cell permeability was evaluated by leakage of fluorescein isothiocyanate (FITC)-dextran. Cellular NO production was measured by the method of nitric acid reductase. Ani HBr at 20 μg/mL significantly increased the viability of ECs with LPS challenge, but significantly inhibited the cell viability at 80 μg/mL, showing a bidirectional regulation of cell viability by Ani HBr. Ani HBr had not significantly change the LPS-induced EC proliferation. Ani HBr significantly reversed the induction of LPS on EC apoptosis. Ani HBr reinstated the LPS-induced glycocalyx and VE-cadherin shedding and adherens junction disruption. Ani HBr significantly alleviated LPS-induced EC layer permeability and NO production. Ani HBr protects ECs against LPS-induced increase in cell barrier permeability and nitric oxide production via preserving the integrity of glycocalyx. Ani HBr is a promising drug to rescue or protect the glycocalyx.

Microvascular Mimetics for the Study of Leukocyte-Endothelial Interactions.

The pathophysiological increase in microvascular permeability plays a well-known role in the onset and progression of diseases like sepsis and atherosclerosis. However, how interactions between neutrophils and the endothelium alter vesselpermeability is often debated. In this study, we introduce amicrofluidic, silicon-membrane enabled vascular mimetic (μSiM-MVM) for investigating the role of neutrophils in inflammation-associated microvascular permeability. In utilizing optically transparent silicon nanomembrane technology, we build on previous microvascular models byenabling in situ observations of neutrophil-endothelium interactions. To evaluate the effects of neutrophil transmigration on microvascular model permeability, we established and validated electrical (transendothelial electrical resistance and impedance) and small molecule permeability assays that allow for the in situ quantification of temporal changes in endothelium junctional integrity. Analysis of neutrophil-expressed β1 integrins revealed a prominent role of neutrophil transmigration and basement membrane interactions in increased microvascular permeability. By utilizing blocking antibodies specific to the β1 subunit, we found that the observed increase in microvascular permeability due to neutrophil transmigration is constrained when neutrophil-basement membrane interactions are blocked. Having demonstrated the value of in situ measurements of small molecule permeability, we then developed and validated a quantitative framework that can be used to interpret barrier permeability for comparisonsto conventional Transwell™ values. Overall, our results demonstrate the potential of the μSiM-MVM in elucidating mechanisms involved in the pathogenesis of inflammatory disease, and provide evidence fora role for neutrophils in inflammation-associated endothelial barrier disruption.

Corrigendum to "JAK2/STAT3 Pathway Was Associated with the Protective Effects of IL-22 on Aortic Dissection with Acute Lung Injury".

[This corrects the article DOI: 10.1155/2017/1917804.].

Resuscitation with centhaquin and 6% hydroxyethyl starch 130/0.4 improves survival in a swine model of hemorrhagic shock: a randomized experimental study.

To investigate the effects of the combination of centhaquin and 6% hydroxyethyl starch 130/0.4 (HES 130/0.4) in a swine model of hemorrhagic shock. Twenty Landrace-Large White pigs were instrumented and subjected to hemorrhagic shock. The animals were randomly allocated in two experimental groups, the control (group CO, n = 10) and the centhaquin groups (0.015mg/kg, n = 10, group CH). Acute hemorrhage was induced by stepwise blood withdrawal (18mL/min) from the internal jugular vein until MAP decreased to 40-45mmHg, whereas anesthesia remained constant. All animals received HES 130/0.4 solution in the resuscitation phase until their mean arterial pressure (MAP) reached 90% of the baseline. The animals were observed for 60min, during which no further resuscitation was attempted. The total amount of blood and the bleeding time did not differ significantly between group CO and group CH (120 ± 13 vs. 120 ± 14mL, p = 0.6; 20 ± 2 vs. 20 ± 1min, p = 0.62, respectively). During the hemorrhagic phase, only a difference in heart rate (97.6 ± 4.4 vs. 128.4 ± 3.6beats/min, p = 0.038) was observed between the two groups. The time required to reach the target MAP was significantly shorter in the centhaquin group compared to controls (13.7 ± 0.4 vs. 19.6 ± 0.84min, p = 0.012). During the resuscitation phase, a statistical significant difference was observed in MAP (75.2 ± 1.6 vs. 89.8 ± 2.1mmHg, p = 0.02) between group CO and group CH. During the observation phase, a statistical significant difference was observed in SVR (1109 ± 32.65 vs. 774.6 ± 21.82dyns/cm5, p = 0.039) and cardiac output (5.82 ± 0.31 vs. 6.9 ± 0.78L/min, p = 0.027) between the two groups. Two animals of group CO and seven animals of group CH survived for 24h (p = 0.008). We observed a marked increase in microvascular capillary permeability in group CO compared to group CH, with the wet/dry weight ratio being significantly higher in group CO compared to group CH (4.8 ± 1.6 vs. 3.08 ± 0.6, p < 0.001). The combination of centhaquin 0.015mg/kg and HES 130/0.4 resulted in shorter time to target MAP, lower wet-to-dry ratio, and better survival rates after resuscitation from hemorrhagic shock.

A Rat Burn Injury Model for Studying Changes in Microvascular Permeability.

The management of burn patients is an extremely complex and clinically challenging for patient care. Aside from the increasing reports of burn injury and morbidity and mortality directly related to it, the pathobiology of burn trauma is not clearly understood. The rat model of burn trauma described here is currently used in research laboratories to study various aspects of burn injury, including vascular dysfunctions. This model demonstrates the infliction of thermal injury in Sprague-Dawley rats using a well-established boiled water approach. We have utilized intravital microscopy to examine the microvascular hyperpermeability, the excessive leakage of proteins and fluids from the intravascular space to the extravascular space in mesenteric postcapillary venules using this model. An increase in microvascular permeability is a strong indicator of microvascular dysfunctions leading to tissue edema in burn trauma.

The role of PP2A in an inflammatory induced increase in Brain Microvascular Permeability

The role of PP2A in an inflammatory induced increase in Brain Microvascular Permeability

Vascular endothelial cell changes in postcardiac surgery acute kidney injury.

Acute kidney injury (AKI) is common complication of cardiac surgery; however, the phenotype of this condition is poorly defined. The aim of this study was to characterize changes in endothelial structure and function that underlie postcardiopulmonary bypass (post-CPB) AKI. Adult pigs ( n = 16) were randomized to undergo the following procedures ( n = 8 per group): group 1: sham operation, neck dissection with 2.5 h of general anesthesia; and group 2: CPB, 2.5 h of cardiopulmonary bypass. CPB resulted in the depletion of specific epitopes of glycosaminoglycans side chains of the endothelial glycocalyx: Dolichos biflorus agglutinin: mean difference (MD) [95% confidence interval (CI)], P value: -0.26 (-0.42, -0.09), P = 0.0024, Triticum vulgaris (wheat germ) agglutinin: -0.83 (-1.2, -0.38), P = 0.0005, and Ulex europaeus agglutinin 1: -0.25 (-0.49, -0.009), P = 0.041; endothelial membrane protein: thrombomodulin: -3.13 (-5.6, -0.65), P = 0.02; and adherens junction: VE-cadherin: -1.06 (-1.98, -0.145), P = 0.02. CPB also resulted in reductions in microvascular cortical perfusion: -0.62 (-1.02, -0.22), P = 0.006, and increased renal cortex adenosine levels: 2.32 (0.83, 3.8), P = 0.0059. These changes were accompanied by significant reduction in creatinine clearance at 1.5 h postintervention, MD 95% CI; -51.7 (-99.7, -3.7), P = 0.037, and at 24 h, MD (95% CI): -47.3 (-87.7, -7.6), P = 0.023, and proteinuria immediately postintervention MD (95% CI): 18.79 (2.17, 35.4), P = 0.03 vs. sham. In our experimental CPB model, endothelial injury was associated with loss of autoregulation, increase in microvascular permeability, and reduced glomerular filtration. Interventions that promote endothelial homeostasis may have clinical utility in the prevention of postcardiac surgery AKI.

Adverse Heart-Lung Interactions in Ventilator-induced Lung Injury.

In the original 1974 in vivo study of ventilator-induced lung injury, Webb and Tierney reported that high Vt with zero positive end-expiratory pressure caused overwhelming lung injury, subsequently shown by others to be due to lung shear stress. To reproduce the lung injury and edema examined in the Webb and Tierney study and to investigate the underlying mechanism thereof. Sprague-Dawley rats weighing approximately 400 g received mechanical ventilation for 60 minutes according to the protocol of Webb and Tierney (airway pressures of 14/0, 30/0, 45/10, 45/0 cm H2O). Additional series of experiments (20 min in duration to ensure all animals survived) were studied to assess permeability (n = 4 per group), echocardiography (n = 4 per group), and right and left ventricular pressure (n = 5 and n = 4 per group, respectively). The original Webb and Tierney results were replicated in terms of lung/body weight ratio (45/0 > 45/10 ≈ 30/0 ≈ 14/0; P < 0.05) and histology. In 45/0, pulmonary edema was overt and rapid, with survival less than 30 minutes. In 45/0 (but not 45/10), there was an increase in microvascular permeability, cyclical abolition of preload, and progressive dilation of the right ventricle. Although left ventricular end-diastolic pressure decreased in 45/10, it increased in 45/0. In a classic model of ventilator-induced lung injury, high peak pressure (and zero positive end-expiratory pressure) causes respiratory swings (obliteration during inspiration) in right ventricular filling and pulmonary perfusion, ultimately resulting in right ventricular failure and dilation. Pulmonary edema was due to increased permeability, which was augmented by a modest (approximately 40%) increase in hydrostatic pressure. The lung injury and acute cor pulmonale is likely due to pulmonary microvascular injury, the mechanism of which is uncertain, but which may be due to cyclic interruption and exaggeration of pulmonary blood flow.

Evaluation of Plasma Albumin as a Potential Prognostic Biomarker in Patients with Traumatic SIRS

Hypoalbuminemia occurs in about 90% of critically ill patients admitted in the intensive care unit (ICU), this is caused by an increase in microvascular permeability (capillary and venous wall) as a result of systemic inflammatory reaction (SIRS) and decreased synthesis of hepatic albumin in acute liver response. The aim of this study is to determine the incidence of hypoalbuminaemia in patients with non-septic SIRS (induced by surgical trauma or multiple trauma) and to assess the plasma albumin level as a potential biomarker of severity in the prognosis of these patients. The albumin plasma level of ICU admitted patients were determined every 24h and 48h, patients were continuously monitored for complications. Hypoalbuminemia is probably the cause of prolonged ileus, gastroparesis, sepsis, fistula and acute renal failure). The statistical processing of data consisted in compiling descriptive statistics on values of albumin, highlighting the albumin-age relationship by the regression method. Calculation of mean plasma albumin values for groups of patients without clinical complications, those with clinical complications or with complications and who died and performing the Scheffe( multiple comparison test), correlation tests between albumin value at 48h and APACHE II score (prediction score Of the critical patient) as well as a descriptive analysis taking into account the 3 g / dl albumin value (factor that differentiates mild to moderate hypoalbuminemia in clinical practice) and performing the non-parametric Chi-Square test for validation of statistical analysis.

Role of β-arrestin-1 in penehyclidine hydrochloride-induced inhibition of LPS-caused increase in pulmonary microvascular permeability in human pulmonary microvascular endothelial cells

Objective To evaluate the role of β-arrestin-1 in penehyclidine hydrochloride(PHC)-induced inhibition of lipopolysaccharide(LPS)-caused increase in pulmonary microvascular permeability in human pulmonary microvascular endothelial cells(PMVECs). Methods Human PMVECs were seeded in 6-well plates(2 ml/well)or in culture flasks(4 ml/flask)at the density of 1×105 cells/ml and divided into 5 groups(n=15 each)using a random number table: empty plasmid transfection group(group C), LPS plus empty plasmid transfection group(LPS group), PHC plus LPS plus empty plasmid transfection group(P+ LPS group), LPS plus β-arrestin-1 short hairpin RNA(shRNA)transfection group(LPS+ shRNA group)and PHC plus LPS plus β-arrestin-1 shRNA transfection group(P+ LPS+ shRNA group). In LPS and LPS+ shRNA groups, the cells were transfected with empty plasmid 1.5 μg or with plasmid containing 15 nmol/L β-arrestin-1 shRNA, LPS with the final concentration of 0.1 μg/ml was added at 24 h of incubation, and the cells were then incubated for 1 h. In P+ LPS and P+ LPS+ shRNA groups, the cells were transfected with empty plasmid 1.5 μg or with plasmid containing 15 nmol/L β-arrestin-1 shRNA, PHC with the final concentration of 2 μg/ml was added at 24 h of incubation, LPS with the final concentration of 0.1 μg/ml was added at 1 h of incubation, and the cells were then incubated for 1 h. The cell permeability was measured using Transwell chambers.The expression of heat shock protein(HSP27)was detected by immunofluorescence.The expression of β-arrestin-1, p38 mitogen-activated protein kinase(p38MAPK)and phosphorylated p38MAPK(p-p38MAPK)was detected by Western blot.The ratio of p-p38MAPK/p38MAPK was calculated. Results Compared with group C, the cell permeability was significantly increased, the expression of HSP27 was up-regulated, p-p38MAPK/p38MAPK ratio was increased, and the expression of β-arrestin-1 was down-regulated in LPS, LPS+ shRNA and P+ LPS+ shRNA groups(P 0.05). Compared with group LPS, the cell permeability was significantly decreased, the expression of HSP27 was down-regulated, p-p38MAPK/p38MAPK ratio was decreased, and the expression of β-arrestin-1 was up-regulated in group P+ LPS, and p-p38MAPK/p38MAPK ratio was significantly increased(P 0.05). Compared with group P+ LPS, the cell permeability was significantly increased, the expression of HSP27 was up-regulated, p-p38MAPK/p38MAPK ratio was increased, and the expression of β-arrestin-1 was down-regulated in group P+ LPS+ shRNA(P<0.05). Conclusion The mechanism by which PHC inhibits LPS-induced increase in pulmonary microvascular permeability is totally related to β-arrestin-1 in human PMVECs. Key words: Arrestins; Cholinergic antagonists; Endotoxins; Lung; Capillary permeability

Nintedanib reduces ventilation-augmented bleomycin-induced epithelial-mesenchymal transition and lung fibrosis through suppression of the Src pathway.

Mechanical ventilation (MV) used in patients with acute respiratory distress syndrome (ARDS) can increase lung inflammation and pulmonary fibrogenesis. Src is crucial in mediating the transforming growth factor (TGF)‐β1‐induced epithelial–mesenchymal transition (EMT) during the fibroproliferative phase of ARDS. Nintedanib, a multitargeted tyrosine kinase inhibitor that directly blocks Src, has been approved for the treatment of idiopathic pulmonary fibrosis. The mechanisms regulating interactions among MV, EMT and Src remain unclear. In this study, we suggested hypothesized that nintedanib can suppress MV‐augmented bleomycin‐induced EMT and pulmonary fibrosis by inhibiting the Src pathway. Five days after administrating bleomycin to mimic acute lung injury (ALI), C57BL/6 mice, either wild‐type or Src‐deficient were exposed to low tidal volume (VT) (6 ml/kg) or high VT (30 ml/kg) MV with room air for 5 hrs. Oral nintedanib was administered once daily in doses of 30, 60 and 100 mg/kg for 5 days before MV. Non‐ventilated mice were used as control groups. Following bleomycin exposure in wild‐type mice, high VT MV induced substantial increases in microvascular permeability, TGF‐β1, malondialdehyde, Masson's trichrome staining, collagen 1a1 gene expression, EMT (identified by colocalization of increased staining of α‐smooth muscle actin and decreased staining of E‐cadherin) and alveolar epithelial apoptosis (P < 0.05). Oral nintedanib, which simulated genetic downregulation of Src signalling using Src‐deficient mice, dampened the MV‐augmented profibrotic mediators, EMT profile, epithelial apoptotic cell death and pathologic fibrotic scores (P < 0.05). Our data indicate that nintedanib reduces high VT MV‐augmented EMT and pulmonary fibrosis after bleomycin‐induced ALI, partly by inhibiting the Src pathway.

S-nitrosylation of VASP at cysteine 64 mediates the inflammation-stimulated increase in microvascular permeability.

We tested the hypothesis that platelet-activating factor (PAF) induces S-nitrosylation of vasodilator-stimulated phosphoprotein (VASP) as a mechanism to reduce microvascular endothelial barrier integrity and stimulate hyperpermeability. PAF elevated S-nitrosylation of VASP above baseline levels in different endothelial cells and caused hyperpermeability. To ascertain the importance of endothelial nitric oxide synthase (eNOS) subcellular location in this process, we used ECV-304 cells transfected with cytosolic eNOS (GFPeNOSG2A) and plasma membrane eNOS (GFPeNOSCAAX). PAF induced S-nitrosylation of VASP in cells with cytosolic eNOS but not in cells wherein eNOS is anchored to the cell membrane. Reconstitution of VASP knockout myocardial endothelial cells with cysteine mutants of VASP demonstrated that S-nitrosylation of cysteine 64 is associated with PAF-induced hyperpermeability. We propose that regulation of VASP contributes to endothelial cell barrier integrity and to the onset of hyperpermeability. S-nitrosylation of VASP inhibits its function in barrier integrity and leads to endothelial monolayer hyperpermeability in response to PAF, a representative proinflammatory agonist.NEW & NOTEWORTHY Here, we demonstrate that S-nitrosylation of vasodilator-stimulated phosphoprotein (VASP) on C64 is a mechanism for the onset of platelet-activating factor-induced hyperpermeability. Our results reveal a dual role of VASP in endothelial permeability. In addition to its well-documented function in barrier integrity, we show that S-nitrosylation of VASP contributes to the onset of endothelial permeability.

Valproic Acid Treatment Inhibits Vasopermeability and Improves Survival in Rats With Lethal Scald Injury.

The aim of this study was to examine whether administration of valproic acid (VPA), a histone deacetylase inhibitor, inhibits proinflammatory mediators and ameliorate visceral vasopermeability both in a rat model of major burn, and also in rat cultured endothelial cells stimulated with permeability evoking mediators. SD rats were subjected to a 50% TBSA full-thickness scald injury, and treated with either saline or VPA (300 mg/kg) intraperitoneally. Pulmonary vascular endothelial growth factor (VEGF), myeloperoxidase (MPO), pulmonary microvascular permeability, water content, and acetylation of histone H3K9 of lungs were evaluated. In addition, pulmonary microvascular endothelial cells (PMECs) from male SD rats were cultured. With then, MPO, VEGF, histone acetylation, and the permeability of PMECs were investigated. Lethal scald injury resulted in a significant increase in microvascular permeability and water content of lung, accompanied by a significant elevation of the content of VEGF and activity of MPO, and a decrease of histone acetylation. VPA treatment significantly alleviated the microvascular permeability and water content of lung, lowered the levels of VEGF and MPO, and promoted acetylation of histone H3K9 following scald injury. Moreover, VPA reduced permeability of monolayer PMECs subjected to scald serum challenge, reduced the level of MPO and VEGF in supernatants, and promoted acetylation of histone H3K9 in PMECs. These results indicated that VPA can protect pulmonary microvascular endothelial barrier, alleviate proinflammatory mediators-evoked vascular hyperpermeability and tissue edema and improve the survival rate of rats subjected to lethal scald injury.

Dasatinib inhibits actin fiber reorganization and promotes endothelial cell permeability through RhoA-ROCK pathway.

Treatment with dasatinib, a tyrosine kinase inhibitor, is associated with edema, pleural effusion, and pulmonary edema. We investigated the effect of dasatinib on the barrier function of human microvascular endothelial cells‐1 (HMEC‐1) in vitro and in vivo. The permeability of HMEC‐1 to fluorescein isothiocyante (FITC)‐dextran increased in Transwell chambers within 5 min following the addition of therapeutic concentrations of dasatinib. The change in permeability was associated with increased activation of RhoA GTPase and its effector Rho‐associated coiled‐coil kinase 1(ROCK1). RhoA inhibitor C3 transferase almost completely inhibited dasatinib‐induced increase in permeability. Under similar conditions, imatinib had no effect on permeability or activation of RhoA. Since integrin‐induced cell spreading suppresses RhoA activation, we examined the effect of dasatinib on cell spreading on fibronectin substrate. Dasatinib impaired endothelial cell spreading in a concentration‐dependent manner and induced disorganization of actin fibers. Tyrosine kinases play an essential role in transmitting signals from integrins to RhoA and we examined tyrosine phosphorylation of several cytoskeletal proteins. Dasatinib markedly inhibited tyrosine phosphorylation of p130 Crk‐associated substrate (p130cas), paxillin and vinculin. These results suggest that the inhibition of tyrosine phosphorylation of the focal adhesion plaque components by dasatinib may alter the assembly of actin fibers resulting in the activation of RhoA/ROCK pathway. Consistent with these findings, dasatinib‐induced increase in the permeability was blocked by ROCK inhibitor y27632. In vivo administration of y27632, significantly inhibited the dasatinib‐induced extravasation of Evans blue in mice and dasatinib‐induced increase in microvascular permeability was attenuated in ROCK1‐deficient mice. These findings suggest that ROCK inhibitors could serve as therapeutic modalities to ameliorate the dasatinib‐induced pulmonary changes.

Dexamethasone reverses the effects of high glucose on human retinal endothelial cell permeability and proliferation in vitro

Diabetic macular oedema (DMO), a leading cause of preventable visual loss in the working population, is caused by an increase in microvascular endothelial cell permeability, and its prevalence is on the increase in parallel with the rising worldwide prevalence of diabetes. It is known that retinal vascular leakage in DMO is contributed to by VEGF upregulation as well as non-VEGF dependent inflammatory pathways, and the potential use of anti-inflammatory agents such as the glucocorticoids, including dexamethasone are being extensively studied. However, the mechanisms of action of dexamethasone in DMO reduction are not fully understood. Using human primary retinal endothelial cells (REC) the in vitro effect of dexamethasone in modulating the proliferation, permeability and gene expression of key tight and adheren junction components, and the expression of angiopoietins (Ang) 1 and 2 in high (25 mM) glucose conditions were investigated. High glucose decreased REC proliferation, an effect that was reversed by dexamethasone. High glucose conditions significantly increased REC permeability and decreased claudin-5, occludin and JAM-A gene expression; dexamethasone was effective in partially reversing these changes, restoring EC permeability to the normal or near normal state. High glucose levels resulted in reduction of Ang1 secretion, although Ang2 levels were consistently high. DEX increased Ang1 and decreased Ang2, indicating that the balance of Ang1/Ang2 may be important in determining functional changes in REC under high glucose conditions.

The mechanism underlying alpinetin-mediated alleviation of pancreatitis-associated lung injury through upregulating aquaporin-1.

Characterized by its acute onset, critical condition, poor prognosis, and high mortality rate, severe acute pancreatitis (SAP) can cause multiple organ failure at its early stage, particularly acute lung injury (ALI). The pathogenesis of ALI is diffuse alveolar damage, including an increase in pulmonary microvascular permeability, a decrease in compliance, and invasion of many inflammatory cells. Corticosteroids are the main treatment method for ALI; however, the associated high toxicity and side effects induce pain in patients. Recent studies show that the effective components in many traditional Chinese medicines can effectively inhibit inflammation with few side effects, which can decrease the complications caused by steroid consumption. Based on these observations, the main objective of the current study is to investigate the effect of alpinetin, which is a flavonoid extracted from Alpinia katsumadai Hayata, on treating lung injury induced by SAP and to explore the mechanism underlying the alpinetin-mediated decrease in the extent of ALI. In this study, we have shown through in vitro experiments that a therapeutic dose of alpinetin can promote human pulmonary microvascular endothelial cell proliferation. We have also shown via in vitro and in vivo experiments that alpinetin upregulates aquaporin-1 and, thereby, inhibits tumor necrosis factor-α expression as well as reduces the degree of lung injury. Overall, our study shows that alpinetin alleviates SAP-induced ALI. The likely molecular mechanism includes upregulated aquaporin expression, which inhibits tumor necrosis factor-α and, thus, alleviates SAP-induced ALI.