Submitted to: Journal of Leukocyte Biology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/8/2006
Publication Date: 3/1/2007
Citation: Gonzalez, A.L., El-Bjeirami, W., West, J.L., McIntire, L.V., Smith, C.W. 2007. Transendothelial migration enhances integrin-dependent human neutrophil chemokinesis. Journal of Leukocyte Biology. 81:686-695. Interpretive Summary: Tissue injury results in inflammation at the site of the injury. While inflammation is helpful in protecting against infection and promoting healing, it may delay healing or cause further tissue injury if the inflammation is excessive. This is believed to be the case with chronic diabetic wounds where inflammation continues as if the shut-off mechanisms are defective. To investigate the mechanisms that prevent resolution of inflammation, we studied a model of inflammation in tissue culture using some bioengineering techniques to create an artificial tissue surface on which to analyze the behavior of one cell type that is very important in inflammation, the blood neutrophil. We collected neutrophils after they crawled through endothelial cells (the cells that line the blood vessels) and determined their ability to migrate on specific molecules attached to the artificial tissue surface. The studies demonstrated that blood neutrophils change the cell surface molecules they use to interact with tissues molecules when they migrate through the endothelial cells. A neutrophil cell surface molecule called alpha M integrin (or Mac-1) is very important, and new types of integrins are increased in function after neutrophils migration through endothelial cells. These basic studies provide information that will be used in the analysis of obesity induced alterations in the inflammatory response to tissue injury.
Technical Abstract: Transendothelial migration of neutrophils induces phenotypic changes that influence the interactions of neutrophils with extravascular tissue components. To assess the influence of transmigration on neutrophil chemokinetic motility, we used polyethylene glycol hydrogels covalently modified with specific peptide sequences relevant to extracellular matrix proteins. We evaluated fMLP-stimulated human neutrophil motility on peptides Arg-Gly-Asp-Ser (RGDS) and TMKIIPFNRTLIGG (P2), alone and in combination. RGDS is a bioactive sequence found in a number of proteins, and P2 is a membrane-activated complex-1 (Mac-1) ligand located in the gamma-chain of the fibrinogen protein. We evaluated, via video microscopy, cell motility by measuring cell displacement from origin and total accumulated distance traveled and then calculated average velocity. Results indicate that although adhesion and shape change were supported by hydrogels containing RGD alone, motility was not. Mac-1-dependent motility was supported on hydrogels containing P2 alone. Motility was enhanced through combined presentation of RGD and P2, engaging Mac-1, alpha(V)beta(3), and beta(1) integrins. Naïve neutrophil motility on combined peptide substrates was dependent on Mac-1, and alpha(4)beta(1) while alpha(6)beta(1) contributed to speed and linear movement. Transmigrated neutrophil motility was dependent on alpha(v)beta(3) and alpha(5)beta(1), and alpha(4)beta(1), alpha(6)beta(1), and Mac-1 contributed to speed and linear motion. Together, the data demonstrate that efficient neutrophil migration, dependent on multi-integrin interaction, is enhanced after transendothelial migration.