Cytokine-induced expression of tPA is differentially modulated by NO and ROS in rat mesangial cells.
BACKGROUND
Dysregulated expression of diverse proteases and their specific inhibitors is critical for the increase in extracellular matrix accumulation that accompanies chronic inflammatory and sclerotic processes within the renal mesangium. Within the activating cascade of several proteases, the plasminogen system plays an important role.


METHODS
We tested for modulatory effects of the nitric oxide (NO) donors S-nitroso-N-acetyl-D,L-penicillamine and DETA-NONOate, and the superoxide-generating system hypoxanthine/xanthine oxidase (HXXO) on the expression and activity of tissue plasminogen activator (tPA) by ELISA and Northern blotting.


RESULTS
Interleukin-1beta (IL-1beta)-induced tPA and plasminogen activator inhibitor (PAI)-1 mRNA and supernatant tPA antigen were significantly inhibited by both NO donors, which resulted in a net decrease in the IL-1beta-evoked tPA enzyme activity in the conditioned media. Addition of the NO-synthase inhibitor N-monomethyl l-arginine markedly increased the cytokine-triggered tPA- and PAI-1 mRNA levels, respectively. In contrast, HXXO caused a marked amplification of the IL-1beta-induced steady-state tPA mRNA level and tPA enzyme activity that was blocked by catalase. Since MnTBAP, a superoxide dismutase mimetic, had no effects on the amplification of mRNA levels, we suggest that H2O2 is the candidate reactive oxygen species (ROS) responsible for the potentiation of IL-1beta-triggered tPA and PAI-1 expression.


CONCLUSIONS
The temporal relationship between NO and ROS generation is a critical step in the modulation of tPA and PAI-1 expression in mesangial cells and may account for a dysregulation of matrix turnover during inflammatory processes in the renal mesangium.
Eberhardt
Wolfgang
W
Pharmazentrum Frankfurt, Klinikum der Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany.
Beck
Karl-Friedrich
KF
Pfeilschifter
Josef
J
D000818:Animals; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D005920:Glomerular Mesangium / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology*; D020780:Matrix Metalloproteinase 9 / Q000235:genetics; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009603:Nitroso Compounds / Q000494:pharmacology; D016877:Oxidants / Q000494:pharmacology; D010396:Penicillamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000235:genetics; D010959:Tissue Plasminogen Activator / Q000235:genetics* / Q000378:metabolism
D007375:Interleukin-1; D020030:Nitric Oxide Donors; D009603:Nitroso Compounds; D016877:Oxidants; D017395:Plasminogen Activator Inhibitor 1; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; C110881:S-nitro-N-acetylpenicillamine; D019715:Tissue Inhibitor of Metalloproteinase-1; C094210:2,2'-(hydroxynitrosohydrazono)bis-ethanamine; D009569:Nitric Oxide; D006861:Hydrogen Peroxide; D010959:Tissue Plasminogen Activator; D020780:Matrix Metalloproteinase 9; D010396:Penicillamine; D006152:Cyclic GMP