Activation of endothelial extracellular signal-regulated kinase is essential for neutrophil transmigration: potential involvement of a soluble neutrophil factor in endothelial activation.
During an inflammatory response induced by infection or injury, leukocytes traverse the endothelial barrier into the tissue space. Extravasation of leukocytes is a multistep process involving rolling, tethering, firm adhesion to the endothelium, and finally, transendothelial migration, the least characterized step in the process. The resting endothelium is normally impermeable to leukocytes; thus, during inflammation, intracellular signals that modulate endothelial permeability are activated to facilitate the paracellular passage of leukocytes. Using a static in vitro assay of neutrophil transmigration across human umbilical vein endothelium, a panel of inhibitors of intracellular signaling was screened for their ability to inhibit transmigration. PD98059, a specific inhibitor of extracellular signal-regulated kinase (ERK) 1/2 activation, inhibited both transmigration across TNF-alpha-activated endothelium and transmigration induced by the chemoattractant fMLP in a dose-dependent manner. PD98059 did not inhibit neutrophil chemotaxis in the absence of an endothelial barrier nor neutrophil adhesion to the endothelium, suggesting that its effect was on the endothelium, and furthermore, that endothelial ERK activation may be important for transmigration. We demonstrate in this study that endothelial ERK is indeed activated during neutrophil transmigration and that its activation is dependent on the addition of neutrophils to the endothelium. Further characterization showed that the trigger for endothelial ERK activation is a soluble protein of molecular mass approximately 30 kDa released from neutrophils after activation.
Stein
Brian N
BN
Hanson Institute, Institute of Medical and Veterinary Science, and Department of Medicine, University of Adelaide, Adelaide, Australia.
Gamble
Jennifer R
JR
Pitson
Stuart M
SM
Vadas
Mathew A
MA
Khew-Goodall
Yeesim
Y
D019138:Antibodies, Blocking / Q000494:pharmacology; D018821:CD18 Antigens / Q000276:immunology / Q000502:physiology; D002448:Cell Adhesion / Q000187:drug effects; D002464:Cell Migration Inhibition; D002478:Cells, Cultured; D002634:Chemotaxis, Leukocyte / Q000187:drug effects; D017077:Culture Media, Conditioned / Q000032:analysis / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D048728:MAP Kinase Kinase Kinase 1; D020930:MAP Kinase Kinase Kinases / Q000037:antagonists & inhibitors; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008970:Molecular Weight; D018375:Neutrophil Activation / Q000187:drug effects / Q000502:physiology*; D020556:Neutrophil Infiltration / Q000187:drug effects / Q000502:physiology*; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects / Q000201:enzymology* / Q000502:physiology; D012995:Solubility
D019138:Antibodies, Blocking; D018821:CD18 Antigens; D017077:Culture Media, Conditioned; D004791:Enzyme Inhibitors; D005419:Flavonoids; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; D020930:MAP Kinase Kinase Kinases; C482576:MAP3K1 protein, human; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one