Faculty Opinions recommendation of ESAM supports neutrophil extravasation, activation of Rho, and VEGF-induced vascular permeability.

✓ Administration of the mucopolysaccharide, carrageenan (CAR), into the hind paw of the rat or mouse induces a local inflammation characterized by increased arachidonic acid metabolism, increased vascular permeability, edema, and neutrophil extravasation. Carrageenan-induced hind-paw inflammation is inhibited by prostaglandin synthesis inhibitors, and this assay predicts the clinical success of anti-inflammatory agents in reducing peripheral inflammation. The purpose of this study was to determine if intraventricular injection of CAR would induce brain inflammation similar to that evoked by CAR in peripheral tissues. The present study demonstrates that CAR injection into the ventricles of the mouse brain does in fact induce an inflammatory response very similar to that caused by injection of CAR into the peripheral tissues. The brain response to CAR was dose-dependent, with the maximum increase in cerebrovascular permeability to iodine-125-labeled human serum albumin and percent brain water occurring after injection of 50 µg CAR. As is seen in CAR-induced inflammation of the hind paw, the maximum increase in brain vascular permeability occurred 4 hours after CAR injection. Histological analysis of brains 4 hours after CAR administration showed global neutrophil extravasation into the subarachnoid space and evidence of focal neuronal swelling. Methotrexate-induced neutropenia, however, failed to diminish the permeability response to CAR. Gas chromatographic and mass spectrometric measurements of brain prostaglandins 4 hours after CAR injection revealed a significantly increased level of 6-keto-prostaglandin F1α. These results indicate that a significant increase in prostacyclin, the pro-inflammatory arachidonic acid metabolite, during CAR-induced brain inflammation is likely. These studies suggest that CAR-induced brain inflammation may be a useful model on which to test the efficacy of anti-inflammatory agents in the brain, as well as providing information concerning the mediators and mechanisms by which the brain may sustain inflammatory injury.

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Dynamics of neutrophil extravasation and vascular permeability are uncoupled during aseptic cutaneous wounding

AJP Cell Physiology ◽

10.1152/ajpcell.00520.2008 ◽

2009 ◽

Vol 296 (4) ◽

pp. C848-C856 ◽

Cited By ~ 65

Author(s):

Min-Ho Kim ◽

Fitz-Roy E. Curry ◽

Scott I. Simon

Keyword(s):

Vascular Permeability ◽

Enhanced Green Fluorescent Protein ◽

Fluorescent Protein ◽

Imaging Technique ◽

Rho Kinase ◽

Polymorphonuclear Neutrophils ◽

Molecular Junction ◽

Neutrophil Extravasation ◽

Green Fluorescent ◽

Transport Of Macromolecules

Transport of macromolecules and transmigration of leukocytes across vascular endothelium are regulated by a tight molecular junction, but the mechanisms by which these two inflammatory events are differentially controlled in time and magnitude during aseptic cutaneous wounding remain elusive. A real-time fluorescence imaging technique was developed to simultaneously track influx of Alexa 680-labeled albumin and genetically tagged enhanced green fluorescent protein-neutrophils [polymorphonuclear neutrophils (PMN)] within the wound bed. Vascular permeability increased approximately threefold more rapidly than the rate of PMN influx, reaching a maximum at 12 h, on the order of ∼0.15% per minute versus ∼0.05% per minute for PMN influx, which peaked at 18 h. Systemic depletion of PMN with antibody blocked their extravasation to the wound but did not alter the increase in vascular permeability. In contrast, pretreatment with antiplatelet GPIb decreased permeability by 25% and PMN influx by 50%. Hyperpermeability stimulated by the endothelium-specific agonists VEGF or thrombin at 24 h postwounding was completely inhibited by blocking Rho-kinase-dependent signaling, whereas less inhibition was observed at 1 h and neutrophil influx was not perturbed. These data suggest that in aseptic wounds, the endothelium maintains a tight junctional barrier to protein leakage that is independent of neutrophil transmigration, partially dependent on circulating platelets, and associated with Rho-kinase-dependent signaling.

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ESAM supports neutrophil extravasation, activation of Rho, and VEGF-induced vascular permeability

Journal of Experimental Medicine ◽

10.1084/jem.20060565 ◽

2006 ◽

Vol 203 (7) ◽

pp. 1671-1677 ◽

Cited By ~ 153

Author(s):

Frank Wegmann ◽

Björn Petri ◽

Alexander Georg Khandoga ◽

Christian Moser ◽

Andrej Khandoga ◽

...

Keyword(s):

Endothelial Cell ◽

Vascular Permeability ◽

Tight Junctions ◽

Inhibitory Effect ◽

Leukocyte Rolling ◽

Vascular Endothelial ◽

Cremaster Muscle ◽

Neutrophil Extravasation ◽

Leukocyte Extravasation ◽

Endothelial Growth Factor

Endothelial cell–selective adhesion molecule (ESAM) is specifically expressed at endothelial tight junctions and on platelets. To test whether ESAM is involved in leukocyte extravasation, we have generated mice carrying a disrupted ESAM gene and analyzed them in three different inflammation models. We found that recruitment of lymphocytes into inflamed skin was unaffected by the gene disruption. However, the migration of neutrophils into chemically inflamed peritoneum was inhibited by 70% at 2 h after stimulation, recovering at later time points. Analyzing neutrophil extravasation directly by intravital microscopy in the cremaster muscle revealed that leukocyte extravasation was reduced (50%) in ESAM−/− mice without affecting leukocyte rolling and adhesion. Depletion of >98% of circulating platelets did not abolish the ESAM deficiency–related inhibitory effect on neutrophil extravasation, indicating that it is only ESAM at endothelial tight junctions that is relevant for the extravasation process. Knocking down ESAM expression in endothelial cells resulted in reduced levels of activated Rho, a GTPase implicated in the destabilization of tight junctions. Indeed, vascular permeability stimulated by vascular endothelial growth factor was reduced in ESAM−/− mice. Collectively, ESAM at endothelial tight junctions participates in the migration of neutrophils through the vessel wall, possibly by influencing endothelial cell contacts.

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ESAM supports neutrophil extravasation, activation of Rho, and VEGF-induced vascular permeability

The Journal of Cell Biology ◽

10.1083/jcb1742oia2 ◽

2006 ◽

Vol 174 (2) ◽

pp. i2-i2

Author(s):

Frank Wegmann ◽

Björn Petri ◽

Alexander Georg Khandoga ◽

Christian Moser ◽

Andrej Khandoga ◽

...

Keyword(s):

Vascular Permeability ◽

Neutrophil Extravasation

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Cortactin deficiency is associated with reduced neutrophil recruitment but increased vascular permeability in vivo

Journal of Experimental Medicine ◽

10.1084/jem.20101920 ◽

2011 ◽

Vol 208 (8) ◽

pp. 1721-1735 ◽

Cited By ~ 96

Author(s):

Michael Schnoor ◽

Frank P.L. Lai ◽

Alexander Zarbock ◽

Ruth Kläver ◽

Christian Polaschegg ◽

...

Keyword(s):

Endothelial Cells ◽

Vascular Permeability ◽

Intercellular Adhesion Molecule ◽

Intercellular Adhesion Molecule 1 ◽

Rolling Velocity ◽

Molecular Events ◽

Neutrophil Extravasation ◽

Integrin Ligands ◽

Guanosine Triphosphatase

Neutrophil extravasation and the regulation of vascular permeability require dynamic actin rearrangements in the endothelium. In this study, we analyzed in vivo whether these processes require the function of the actin nucleation–promoting factor cortactin. Basal vascular permeability for high molecular weight substances was enhanced in cortactin-deficient mice. Despite this leakiness, neutrophil extravasation in the tumor necrosis factor–stimulated cremaster was inhibited by the loss of cortactin. The permeability defect was caused by reduced levels of activated Rap1 (Ras-related protein 1) in endothelial cells and could be rescued by activating Rap1 via the guanosine triphosphatase (GTPase) exchange factor EPAC (exchange protein directly activated by cAMP). The defect in neutrophil extravasation was caused by enhanced rolling velocity and reduced adhesion in postcapillary venules. Impaired rolling interactions were linked to contributions of β2-integrin ligands, and firm adhesion was compromised by reduced ICAM-1 (intercellular adhesion molecule 1) clustering around neutrophils. A signaling process known to be critical for the formation of ICAM-1–enriched contact areas and for transendothelial migration, the ICAM-1–mediated activation of the GTPase RhoG was blocked in cortactin-deficient endothelial cells. Our results represent the first physiological evidence that cortactin is crucial for orchestrating the molecular events leading to proper endothelial barrier function and leukocyte recruitment in vivo.

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