Interleukin-4 stimulates expression of urokinase-type-plasminogen activator in cultured human foreskin microvascular endothelial cells.
The effect of interleukin-4 (IL-4) on the fibrinolytic system of human microvascular and macrovascular endothelial cells in culture was studied. Only foreskin microvascular endothelial cells (EC) responded to IL-4 treatment with a dose- and time-dependent increase in urokinase-type plasminogen activator (u-PA) (control: 3.0 +/- 0.8 ng/10(5) cells/24 h; 200 U/mL IL-4: 6.7 +/- 0.8 ng/10(5) cells/24 h), whereas human macrovascular EC remained unaffected. A maximum effect was achieved with 200 U/mL IL-4. Little u-PA activity was detected in the conditioned media of human foreskin microvascular EC (HFMEC) treated without and with IL-4 before plasmin treatment (control: 0.03 +/- 0.003 IU/10(5) cells/20 h; 200 U/mL IL-4: 0.09 +/- 0.007 IU/10(5) cells/20 h). These values increased to 0.18 +/- 0.02 IU/10(5) cells/20 h and 0.53 +/- 0.04 IU/10(5) cells/20 h, respectively, after plasmin treatment, indicating that u-PA is released by HFMEC predominantly in its inactive precursor form single-chain u-PA (scu-PA). u-PA activity increased also in the cell lysates of HFMEC up to 2.5-fold after IL-4 treatment. Plasminogen activator inhibitor type-1 (PAI-1) levels produced by HFMEC remained unaffected by IL-4, whereas tissue-type plasminogen activator (t-PA) levels were slightly decreased when HFMEC were treated with IL-4. These findings were also reflected in the specific mRNA levels as determined by Northern blotting. u-PA-specific mRNA increased significantly in HFMEC in the presence of IL-4, whereas t-PA mRNA and PAI-1-specific mRNA in HFMEC and u-PA specific mRNA in human saphenous vein EC (HSVEC) remained unaffected by IL-4 treatment. Our findings suggest a role for IL-4 in the process of angiogenesis, in addition to its known proliferative effect on human microvascular EC, by increasing the fibrinolytic potential of such EC, thereby facilitating extracellular proteolysis and cell migration.
Department of Diagnostic Haematology, Royal Melbourne Hospital, Parkville, Victoria, Australia.
J
J
Wojta
M
M
Gallicchio
H
H
Zoellner
E L
EL
Filonzi
J A
JA
Hamilton
K
K
McGrath
D015152:Blotting, Northern; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000201:enzymology*; D005341:Fibrinolysin / Q000494:pharmacology; D015870:Gene Expression; D006801:Humans; D015847:Interleukin-4 / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D008833:Microcirculation; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D010959:Tissue Plasminogen Activator / Q000235:genetics / Q000378:metabolism; D014568:Urokinase-Type Plasminogen Activator / Q000235:genetics / Q000378:metabolism*
D017395:Plasminogen Activator Inhibitor 1; D012333:RNA, Messenger; D003609:Dactinomycin; D015847:Interleukin-4; D003513:Cycloheximide; D010959:Tissue Plasminogen Activator; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator