Increased expression of tissue plasminogen activator and its inhibitor and reduced fibrinolytic potential of human endothelial cells cultured in elevated glucose.
In diabetic patients, elevated plasma levels of t-PA and PAI-1 accompany impaired fibrinolysis. To identify mechanisms for these abnormalities, we examined whether vascular endothelial cells exposed to high glucose upregulate t-PA and PAI-1 production and whether ambient PA activity is decreased concomitantly. In 17 cultures of human umbilical vein endothelial cells grown to confluency in 30 mM glucose, the t-PA antigen released to the medium in 24 h was (median) 52 ng/10(6) cells (range 10-384) and the PAI-1 antigen was 872 ng/10(6) cells (range 217-2074)--both greater (P less than 0.02) than the amounts released by paired control cultures grown in 5 mM glucose--29 ng/10(6) cells (range 7.5-216) and 461 ng/10(6) cells (range 230-3215), respectively. In the presence of high glucose, the steady-state levels of t-PA and PAI-1 mRNAs were increased correspondingly (median 142 and 183% of control, respectively, P less than 0.05); high glucose per se and hypertonicity contributed to the upregulation in additive fashion. The PA activity of conditioned medium from cultures exposed to high glucose was 0.4 IU/ml (range 0.2-0.6), which was significantly lower (P less than 0.02) than the PA activity of control medium (0.5 IU/ml, range 0.2-0.9). No difference was observed when comparing the PA activities of acidified conditioned media, expected to be depleted of inhibitors. Thus, high glucose coordinately upregulates endothelial t-PA and PAI-1 expression through effects exerted at the pretranslational level and enhanced by even mild degrees of hypertonicity.(ABSTRACT TRUNCATED AT 250 WORDS)
Maiello
M
M
Department of Endocrinology and Metabolism, University of Genoa, Italy.
Boeri
D
D
Podesta
F
F
Cagliero
E
E
Vichi
M
M
Odetti
P
P
Adezati
L
L
Lorenzi
M
M
D002478:Cells, Cultured; D003470:Culture Media; D003920:Diabetes Mellitus / Q000097:blood / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects*; D005342:Fibrinolysis / Q000187:drug effects* / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects*; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D015849:Plasminogen Inactivators / Q000378:metabolism*; D010959:Tissue Plasminogen Activator / Q000096:biosynthesis / Q000187:drug effects*; D014158:Transcription, Genetic; D015854:Up-Regulation / Q000187:drug effects
D003470:Culture Media; D015849:Plasminogen Inactivators; D010959:Tissue Plasminogen Activator; D005947:Glucose