Reduced expression,of junctional adhesion molecule and platelet/endothelial cell adhesion molecule-1 (CD31) at human vascular endothelial junctions by cytokines tumor necrosis factor-alpha plus interferon-gamma does not reduce leukocyte transmigration under flow

The combination of tumor necrosis factor (TNF)-alpha plus interferon (IFN)- gamma has been shown previously to promote redistribution of platelet/endot helial cell adhesion molecule-1 (PECAM-1) (CD31), junctional adhesion molec ule (JAM), and VE-cadherin away from lateral junctions of human umbilical v ein endothelial cell monolayers. in parallel, neutrophil transmigration was significantly reduced. Because PECAM-1 and JAM have been implicated in leu kocyte transmigration, the observed redistribution by cytokine activation w as presumed to represent the mechanism causing decreased transmigration und er static conditions. The current results confirm that culture of human umb ilical vein endothelial cells with TNF-alpha plus IFN-gamma caused a decrea se in surface-expressed and junctional-localized JAM and PECAM-1, but did n ot cause decreased leukocyte transmigration in an in vitro flow assay. Furt hermore, blocking monoclonal antibody to PECAM-1 still significantly reduce d monocyte transmigration, demonstrating that it retains a functional role even though its levels were reduced and redistributed away from junctions, whereas a panel of monoclonal antibodies to JAM failed to reduce leukocyte transmigration. Given the alterations in junction protein location, permeab ility function was assessed. IFN-gamma alone or TNF-alpha plus IFN-gamma si gnificantly increased permeability, but TNF-alpha alone did not, suggesting lack of correlation between transmigration and loss of permeability. in co nclusion, cytokine activation Induced loss and redistribution of PECAM-1 an d JAM away from lateral junctions, but per se does not negatively regulate either neutrophil or monocyte transmigration under flow.