Epidermal growth factor-like domain 7 suppresses intercellular adhesion molecule 1 expression in response to hypoxia/reoxygenation injury in human coronary artery endothelial cells.
BACKGROUND
Epidermal growth factor-like domain 7 (Egfl7) is a chemoattractant for endothelial cells, and its expression is restricted to endothelial cells. Hypoxia/reoxygenation (H/R) induced endothelial injury that occurs during transplantation contributes to the subsequent development of allograft vasculopathy. We investigated the effect of Egfl7 on endothelial cell intercellular adhesion molecule 1 expression in response to H/R injury.


RESULTS
Human coronary artery endothelial cells were submitted to hypoxia (0.1% O(2)) followed by normoxia (21% O(2)) in the presence or absence of Egfl7 (100 ng/mL). Hypoxia alone increased the expression of Egfl7×140±8% of control at 3 hours (n=6; P<0.05) and 385±50% of control at 6 hours (n=6; P<0.001). Incubation with Egfl7 during the reoxygenation period prevented intercellular adhesion molecule 1 upregulation (mean fluorescence intensity: 5.37±0.92 versus 3.81±0.21; P<0.05; n=4 per group). Nuclear factor-κB nuclear localization on H/R injury was blocked by Egfl7 administration (cytosolic/nuclear ratio of 0.93±0.01 versus 1.44±0.24; P<0.05; n=4 per group). Inhibitor of nuclear factor-κB protein level was significantly reduced on H/R injury (26±4.6% of control expression; P<0.05; n=4 per group); however, concurrent incubation with Egfl7 attenuated this reduction (46±6.2% of control expression; P<0.05 when compared with H/R injury alone; n=4 per group).


CONCLUSIONS
Our study reveals the novel observation that hypoxia upregulates human coronary artery endothelial cells expression of Egfl7 and that Egfl7 inhibits expression of intercellular adhesion molecule 1 subsequent to H/R injury. Mechanistically, Egfl7 prevented nuclear factor-κB nuclear localization and augmented inhibitor of nuclear factor-κB protein levels, suggesting that it inhibits nuclear factor-κB activation, a key step in the inflammatory activation of endothelial cells. Egfl7 may be protective against H/R injury incurred during transplantation and may modulate the events that lead to the development of graft vasculopathy.
Badiwala
Mitesh V
MV
Division of Cardiovascular Surgery, Toronto General Hospital, University Health Network, Toronto, Ontario, Canada.
Tumiati
Laura C
LC
Joseph
Jemy M
JM
Sheshgiri
Rohit
R
Ross
Heather J
HJ
Delgado
Diego H
DH
Rao
Vivek
V
D021581:Active Transport, Cell Nucleus; D002135:Calcium-Binding Proteins; D015687:Cell Hypoxia; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000378:metabolism* / Q000473:pathology; D066255:EGF Family of Proteins; D042783:Endothelial Cells / Q000378:metabolism* / Q000473:pathology; D016228:Endothelial Growth Factors / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis*; D016328:NF-kappa B / Q000378:metabolism; D015427:Reperfusion Injury / Q000378:metabolism / Q000473:pathology
D002135:Calcium-Binding Proteins; D066255:EGF Family of Proteins; C527877:EGFL7 protein, human; D016228:Endothelial Growth Factors; D020672:I-kappa B Proteins; D016328:NF-kappa B; D018799:Intercellular Adhesion Molecule-1