scholarly journals Vascular remodeling alters adhesion protein and cytoskeleton reactions to inflammatory stimuli resulting in enhanced permeability increases in rat venules

2012 ◽  
Vol 113 (7) ◽  
pp. 1110-1120 ◽  
Author(s):  
Dong Yuan ◽  
Pingnian He
Keyword(s):  
Endothelial Cells ◽  
Vascular Remodeling ◽  
Structural Changes ◽  
Platelet Activating Factor ◽  
Fiber Formation ◽  
Confocal Imaging ◽  
Perivascular Cell ◽  
Vascular Walls ◽  
Inflammatory Stimuli ◽  
Microvessel Permeability

Vascular remodeling has been implicated in many inflammation-involved diseases. This study aims to investigate the microvascular remodeling-associated alterations in cell-cell adhesion and cytoskeleton reactions to inflammatory stimuli and their impact on microvessel permeability. Experiments were conducted in individually perfused rat mesenteric venules. Microvessel permeability was determined by measuring hydraulic conductivity (Lp), and endothelial intracellular calcium concentration, [Ca2+]i, was measured in fura-2-perfused vessels. Alterations in VE-cadherin and F-actin arrangement were examined by confocal imaging. Vascular wall cellular composition and structural changes were evaluated by electron microscopy. Vessels exposed to platelet activating factor (PAF) on day 1 were reevaluated 3 days later in rats that had undergone survival surgery. Initial PAF exposure and surgical disturbance increased microvascular wall thickness along with perivascular cell proliferation and altered F-actin arrangement. Although basal permeability was not changed, upon reexposure to PAF, peak endothelial [Ca2+]i was augmented and the peak Lp was 9.3 ± 1.7 times higher than that of day 1. In contrast to patterns of PAF-induced stress fiber formation and VE-cadherin redistribution observed in day 1 vessels, the day 4 vessels at the potentiated Lp peak exhibited wide separations of VE-cadherin between endothelial cells and striking stress fibers throughout the vascular walls. Confocal images and ultrastructural micrographs also revealed that the largely separated VE-cadherin and endothelial gaps were completely covered by F-actin bundles in extended pericyte processes at the PAF-induced Lp peak. These results indicate that inflammation-induced vascular remodeling increased endothelial susceptibility to inflammatory stimuli with augmented Ca2+ response resulting in upregulated contractility and potentiated permeability increase. Weakened adhesions between the endothelial cells and contractile mechanisms are both involved in increasing permeability in the intact microvessels and are aggravated during remodeling. The perivascular cells play important roles in stabilizing the microvessel wall, while lessening an otherwise much greater magnitude of leakage during cytoskeletal contraction.

scholarly journals Temporal and spatial correlation of platelet-activating factor-induced increases in endothelial [Ca2+]i, nitric oxide, and gap formation in intact venules

2011 ◽  
Vol 301 (5) ◽  
pp. H1788-H1797 ◽  
Author(s):  
Xueping Zhou ◽  
Pingnian He
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Platelet Activating Factor ◽  
Cellular Level ◽  
Confocal Imaging ◽  
No Production ◽  
Molecular Signaling ◽  
Gap Formation ◽  
Microvessel Permeability ◽  
Endothelial Gaps

We have previously demonstrated that platelet-activating factor (PAF)-induced increases in microvessel permeability were associated with endothelial gap formation and that the magnitude of peak endothelial intracellular Ca2+ concentration ([Ca2+]i) and nitric oxide (NO) production at the single vessel level determines the degree of the permeability increase. This study aimed to examine whether the magnitudes of PAF-induced peak endothelial [Ca2+]i, NO production, and gap formation are correlated at the individual endothelial cell level in intact rat mesenteric venules. Endothelial gaps were quantified by the accumulation of fluorescent microspheres at endothelial clefts using confocal imaging. Endothelial [Ca2+]i was measured on fura-2- or fluo-4-loaded vessels, and 4,5-diaminofluorescein (DAF-2) was used for NO measurements. The results showed that increases in endothelial [Ca2+]i, NO production, and gap formation occurred in all endothelial cells when vessels were exposed to PAF but manifested a spatial heterogeneity in magnitudes among cells in each vessel. PAF-induced peak endothelial [Ca2+]i preceded the peak NO production by 0.6 min at the cellular level, and the magnitudes of NO production and gap formation linearly correlated with that of the peak endothelial [Ca2+]i in each cell, suggesting that the initial levels of endothelial [Ca2+]i determine downstream NO production and gap formation. These results provide direct evidence from intact venules that inflammatory mediator-induced increases in microvessel permeability are associated with the generalized formation of endothelial gaps around all endothelial cells. The spatial differences in the molecular signaling that were initiated by the heterogeneous endothelial Ca2+ response contribute to the heterogeneity in permeability increases along the microvessel wall during inflammation.

Regulation of coronary venular barrier function by blood borne inflammatory mediators and pharmacological tools: insights from novel microvascular wall models

2012 ◽  
Vol 302 (3) ◽  
pp. H567-H581 ◽  
Author(s):  
Gerd Juchem ◽  
Dominik R. Weiss ◽  
Maria Knott ◽  
Anton Senftl ◽  
Stefan Förch ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Inflammatory Mediators ◽  
Barrier Function ◽  
Platelet Activating Factor ◽  
Fold Increase ◽  
Human Myocardium ◽  
Polymorphonuclear Leucocytes ◽  
Inflammatory Conditions ◽  
Vascular Walls

We hypothesized that postcapillary venules play a central role in the control of the tightness of the coronary system as a whole, particularly under inflammatory conditions. Sandwich cultures of endothelial cells and pericytes of precapillary arteriolar or postcapillary venular origin from human myocardium as models of the respective vascular walls (sandwich cultures of precapillary arteriolar or postcapillary venular origin) were exposed to thrombin and components of the acutely activatable inflammatory system, and their hydraulic conductivity ( LP) was registered. LP of SC-PAO remained low under all conditions (3.24 ± 0.52·10−8cm·s−1·cmH2O−1). In contrast, in the venular wall model, PGE2, platelet-activating factor (PAF), leukotriene B4 (LTB4), IL-6, and IL-8 induced a prompt, concentration-dependent, up to 10-fold increase in LP with synergistic support when combined. PAF and LTB4 released by metabolically cooperating platelets, and polymorphonuclear leucocytes (PMNs) caused selectively venular endothelial cells to contract and to open their clefts widely. This breakdown of the barrier function was preventable and even reversible within 6–8 h by the presence of 50 μM quercetin glucuronide (QG). LTB4 synthesis was facilitated by biochemical involvement of erythrocytes. Platelets segregated in the arterioles and PMNs in the venules of blood-perfused human myocardium (histological studies on donor hearts refused for heart transplantation). Extrapolating these findings to the coronary microcirculation in vivo would imply that the latter's complex functionality after accumulation of blood borne inflammatory mediators can change rapidly due to selective breakdown of the postcapillary venular barrier. The resulting inflammatory edema and venulo-thrombosis will severely impair myocardial performance. The protection afforded by QG could be of particular relevance in the context of cardiosurgical intervention.

Angiopoietins can directly activate endothelial cells and neutrophils to promote proinflammatory responses

Blood ◽  
2005 ◽  
Vol 105 (4) ◽  
pp. 1523-1530 ◽  
Author(s):  
Caroline Lemieux ◽  
Ricardo Maliba ◽  
Judith Favier ◽  
Jean-François Théorêt ◽  
Yahye Merhi ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Vascular Remodeling ◽  
Platelet Activating Factor ◽  
Tyrosine Kinase Receptor ◽  
Neutrophil Adhesion ◽  
Β2 Integrin ◽  
Proinflammatory Responses ◽  
Vessel Maturation ◽  
Endothelial Growth Factors ◽  
Angiopoietin 1

AbstractAngiopoietin-1 (Ang1) and -2 (Ang2) are endothelial growth factors that bind to the tyrosine kinase receptor Tie2 and contribute to orchestrate blood vessel formation during angiogenesis. Ang1 mediates vessel maturation and integrity by the recruitment of pericytes. In contrast, Ang2 is classically considered as a Tie2 antagonist, counteracting the stabilizing action of Ang1. Inflammation exists in a mutually dependent association with angiogenesis and we have therefore studied the capacity of angiopoietins to modulate proinflammatory activities, namely P-selectin translocation and neutrophil adhesion onto endothelial cells. We observed that both Ang1 and Ang2 increased these biologic activities. Furthermore, combination of Ang1/Ang2 induced an additive effect on neutrophil adhesion but not on P-selectin translocation. In an attempt to clarify this phenomenon, we found that angiopoietins can directly activate neutrophils through Tie2 signaling as well as modulate platelet-activating factor (PAF) synthesis and β2 integrin functional up-regulation. Together, our data demonstrate that angiopoietins could promote acute recruitment of leukocytes, which might contribute to facilitate vascular remodeling and angiogenesis.

Leukocyte-platelet aggregate adhesion and vascular permeability in intact microvessels: role of activated endothelial cells

2006 ◽  
Vol 291 (2) ◽  
pp. H591-H599 ◽  
Author(s):  
Pingnian He ◽  
Hong Zhang ◽  
Longkun Zhu ◽  
Yanyan Jiang ◽  
Xueping Zhou
Keyword(s):  
Endothelial Cells ◽  
Tissue Injury ◽  
Leukocyte Adhesion ◽  
Single Cells ◽  
Autologous Blood ◽  
Blood Perfusion ◽  
Endothelial Activation ◽  
Confocal Imaging ◽  
Platelet Aggregate ◽  
Microvessel Permeability

Leukocyte-platelet aggregation and aggregate adhesion have been indicated as biomarkers of the severity of tissue injury during inflammation or ischemic reperfusion. The objective of this study is to investigate the mechanisms of the aggregate adhesion and quantitatively evaluate its relationship with microvessel permeability. A combined autologous blood perfusion with single microvessel perfusion technique was employed in rat mesenteric venular microvessels. The aggregate adhesion was induced by systemic application of TNF-α plus local application of platelet-activating factor (PAF). Changes in permeability were determined by measurements of hydraulic conductivity ( Lp) before and after aggregate adhesion in the same individually perfused microvessels. The compositions of the adherent aggregates were identified with fluorescent labeling and confocal imaging. In contrast to leukocyte adhesion as single cells resulting in no increase in microvessel permeability, aggregate adhesion induced prolonged increases in microvessel Lp(6.1 ± 0.9 times the control, n = 9) indicated by the initial Lpmeasurements after 3 h of blood perfusion, which is distinct from the transient Lpincrease caused by PAF-induced endothelial activation in the absence of blood. Isoproteronol (Iso) attenuated aggregate adhesion-mediated Lpincreases if applied after autologous blood perfusion and prevented the aggregate adhesion if the initial endothelial activation is inhibited by applying Iso before PAF administration but showed less effect on single leukocyte adhesion. This study demonstrated that leukocyte-platelet aggregate adhesion via a mechanism different from that of single leukocyte adhesion caused a prolonged increase in microvessel permeability. Our results also indicate that the initial activation of endothelial cells by PAF plays a crucial role in the initiation of leukocyte-platelet aggregate adhesion.

scholarly journals Enhanced permeability responses to inflammation in streptozotocin-induced diabetic rat venules: Rho-mediated alterations of actin cytoskeleton and VE-cadherin

2014 ◽  
Vol 307 (1) ◽  
pp. H44-H53 ◽  
Author(s):  
Dong Yuan ◽  
Sulei Xu ◽  
Pingnian He
Keyword(s):  
Endothelial Cells ◽  
Microvascular Complications ◽  
Diabetic Rats ◽  
Fiber Formation ◽  
Receptor Expression ◽  
Diabetic Patients ◽  
No Production ◽  
Significant Difference ◽  
Microvessel Permeability ◽  
The Impact

Diabetes is a progressive disease that often leads to microvascular complications. This study investigates the impact of diabetes on microvessel permeability under basal and inflammatory conditions. Streptozotocin-induced diabetic rats were used to mimic type 1 diabetes. Parallel experiments were conducted in intact mesenteric venules in normal rats and diabetic rats experiencing hyperglycemia for 2–3 wk. Microvessel permeability was determined by measuring hydraulic conductivity (Lp). The correlated changes in endothelial intracellular Ca2+ concentration ([Ca2+]i), adherens junctions, and cytoskeleton F-actin were examined with fluorescence imaging. Diabetic vessels showed moderately increased basal Lp, but upon platelet-activating factor (PAF) exposure, these vessels showed an ∼10-fold higher Lp increase than the normal vessels. Concomitantly, we observed higher increases in endothelial [Ca2+]i, enhanced stress fiber formation, vascular endothelial-cadherin separation, and larger gap formation between endothelial cells than those occurring in normal vessels. PAF receptor staining showed no significant difference between normal and diabetic vessels. The application of Rho kinase inhibitor Y27632 did not affect PAF-induced increases in endothelial [Ca2+]i but significantly reduced PAF-induced Lp increases by 90% in diabetic vessels. The application of both Y27632 and nitric oxide (NO) synthase inhibitor attenuated PAF-induced Lp increases more than using one inhibitor alone. Our studies indicate that diabetic conditions prime endothelial cells into a phenotype with increased susceptibility to inflammation without altering receptor expression and that the increased Rho activation and NO production play important roles in exaggerated permeability increases when diabetic vessels were exposed to inflammatory mediators, which may account for the exacerbated vascular dysfunction when diabetic patients are exposed to additional inflammation.

scholarly journals Pericyte migration and proliferation are tightly synchronized to endothelial cell sprouting dynamics

2021 ◽  
Author(s):  
Laura Beth Payne ◽  
Jordan Darden ◽  
Ariana D Suarez-Martinez ◽  
Huaning Zhao ◽  
Alissa Hendricks ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Vascular Remodeling ◽  
Vessel Wall ◽  
Time Lapse ◽  
Confocal Imaging ◽  
Cell Behaviors ◽  
Directional Movement ◽  
Developing Mouse Brain

Abstract Pericytes are critical for microvascular stability and maintenance, among other important physiological functions, yet their involvement in vessel formation processes remains poorly understood. To gain insight into pericyte behaviors during vascular remodeling, we developed two complementary tissue explant models utilizing ‘double reporter’ animals with fluorescently-labeled pericytes and endothelial cells (via Ng2:DsRed and Flk-1:eGFP genes, respectively). Time-lapse confocal imaging of active vessel remodeling within adult connective tissues and embryonic skin revealed a subset of pericytes detaching and migrating away from the vessel wall. Vessel-associated pericytes displayed rapid filopodial sampling near sprouting endothelial cells that emerged from parent vessels to form nascent branches. Pericytes near angiogenic sprouts were also more migratory, initiating persistent and directional movement along newly forming vessels. Pericyte cell divisions coincided more frequently with elongating endothelial sprouts, rather than sprout initiation sites, an observation confirmed with in vivo data from the developing mouse brain. Taken together, these data suggest that (i) pericyte detachment from the vessel wall may represent an important physiological process to enhance endothelial cell plasticity during vascular remodeling, and (ii) pericyte migration and proliferation are highly synchronized with endothelial cell behaviors during the coordinated expansion of a vascular network.

Platelet-activating factor increases endothelial [Ca2+]i and NO production in individually perfused intact microvessels

2005 ◽  
Vol 288 (6) ◽  
pp. H2869-H2877 ◽  
Author(s):  
Longkun Zhu ◽  
Pingnian He
Keyword(s):  
Endothelial Cells ◽  
Platelet Activating Factor ◽  
No Production ◽  
Caveolin 1 ◽  
Microvessel Permeability ◽  
Nos Inhibitor ◽  
The Mean ◽  
Induced Changes ◽  
Dependent Signaling Pathway ◽  
Peak Value

We have demonstrated that inhibition of NO synthase (NOS) in endothelial cells by either the NOS inhibitor Nω-monomethyl-l-arginine (l-NMMA) or the internalization of caveolin-1 scaffolding domain attenuated platelet-activating factor (PAF)-induced increases in microvessel permeability ( Am J Physiol Heart Circ Physiol 286: H195–H201, 2004) indicating the involvement of an NO-dependent signaling pathway. To investigate whether an increase in endothelial cytoplasmic Ca2+ concentration ([Ca2+]i) is the initiating event and Ca2+-dependent NO production is crucial for permeability increases, PAF (10 nM)-induced changes in endothelial [Ca2+]i and NO production were measured in individually perfused rat mesenteric venular microvessels via fluorescence microscopy. When venular microvessels were exposed to PAF, endothelial [Ca2+]i increased from 69 ± 8 nM to a peak value of 374 ± 26 nM within 3 min and then declined to a sustained level at 190 ± 12 nM after 15 min. Inhibition of NOS did not modify PAF-induced increases in endothelial [Ca2+]i. PAF-induced NO production was visualized and quantified at cellular levels in individually perfused microvessels using 4,5-diaminofluorescein diacetate and fluorescence imaging. Increased fluorescence intensity (FI), which is an indication of increased NO production, occurred in 75 ± 7% of endothelial cells in each vessel. The mean maximum FI increase was 140 ± 7% of baseline value. This increased FI was abolished by pretreatment of the vessel with l-NMMA and attenuated in the absence of extracellular Ca2+. These results provide direct evidence from intact microvessels that increased endothelial [Ca2+]i is the initial signal that activates endothelial NOS, and the subsequent increased NO production contributes to PAF-induced increases in microvessel permeability.

The Role of Platelet-Activating Factor in Endothelial Cells

1990 ◽  
Vol 64 (01) ◽  
pp. 099-103 ◽  
Author(s):  
Stephen M Prescott ◽  
Thomas M McIntyre ◽  
Guy A Zimmerman
Keyword(s):  
Endothelial Cells ◽  
Platelet Activating Factor

scholarly journals Automated computational analysis reveals structural changes in the enteric nervous system of nNOS deficient mice

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ben R. Cairns ◽  
Benjamin Jevans ◽  
Atchariya Chanpong ◽  
Dale Moulding ◽  
Conor J. McCann
Keyword(s):  
Machine Learning ◽  
Nervous System ◽  
Enteric Nervous System ◽  
Structural Changes ◽  
Computational Analysis ◽  
Confocal Imaging ◽  
Learning Approaches ◽  
Composition And Structure ◽  
Oxide Synthase ◽  
Computational Image Analysis

AbstractNeuronal nitric oxide synthase (nNOS) neurons play a fundamental role in inhibitory neurotransmission, within the enteric nervous system (ENS), and in the establishment of gut motility patterns. Clinically, loss or disruption of nNOS neurons has been shown in a range of enteric neuropathies. However, the effects of nNOS loss on the composition and structure of the ENS remain poorly understood. The aim of this study was to assess the structural and transcriptional consequences of loss of nNOS neurons within the murine ENS. Expression analysis demonstrated compensatory transcriptional upregulation of pan neuronal and inhibitory neuronal subtype targets within the Nos1−/− colon, compared to control C57BL/6J mice. Conventional confocal imaging; combined with novel machine learning approaches, and automated computational analysis, revealed increased interconnectivity within the Nos1−/− ENS, compared to age-matched control mice, with increases in network density, neural projections and neuronal branching. These findings provide the first direct evidence of structural and molecular remodelling of the ENS, upon loss of nNOS signalling. Further, we demonstrate the utility of machine learning approaches, and automated computational image analysis, in revealing previously undetected; yet potentially clinically relevant, changes in ENS structure which could provide improved understanding of pathological mechanisms across a host of enteric neuropathies.

scholarly journals Vascular Inflammation Is Associated with Loss of Aquaporin 1 Expression on Endothelial Cells and Increased Fluid Leakage in SARS-CoV-2 Infected Golden Syrian Hamsters

Viruses ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 639
Author(s):  
Lisa Allnoch ◽  
Georg Beythien ◽  
Eva Leitzen ◽  
Kathrin Becker ◽  
Franz-Josef Kaup ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Vascular Inflammation ◽  
Intercellular Junctions ◽  
Edema Formation ◽  
Vascular Integrity ◽  
Syrian Hamsters ◽  
Aquaporin 1 ◽  
Vascular Walls ◽  
Transmission Electron ◽  
Mock Infection

Vascular changes represent a characteristic feature of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection leading to a breakdown of the vascular barrier and subsequent edema formation. The aim of this study was to provide a detailed characterization of the vascular alterations during SARS-CoV-2 infection and to evaluate the impaired vascular integrity. Groups of ten golden Syrian hamsters were infected intranasally with SARS-CoV-2 or phosphate-buffered saline (mock infection). Necropsies were performed at 1, 3, 6, and 14 days post-infection (dpi). Lung samples were investigated using hematoxylin and eosin, alcian blue, immunohistochemistry targeting aquaporin 1, CD3, CD204, CD31, laminin, myeloperoxidase, SARS-CoV-2 nucleoprotein, and transmission electron microscopy. SARS-CoV-2 infected animals showed endothelial hypertrophy, endothelialitis, and vasculitis. Inflammation mainly consisted of macrophages and lower numbers of T-lymphocytes and neutrophils/heterophils infiltrating the vascular walls as well as the perivascular region at 3 and 6 dpi. Affected vessels showed edema formation in association with loss of aquaporin 1 on endothelial cells. In addition, an ultrastructural investigation revealed disruption of the endothelium. Summarized, the presented findings indicate that loss of aquaporin 1 entails the loss of intercellular junctions resulting in paracellular leakage of edema as a key pathogenic mechanism in SARS-CoV-2 triggered pulmonary lesions.

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