Modulating effect of serum on the stimulation of plasminogen activator inhibitor 2 production in human gingival fibroblasts by lipopolysaccharide and interleukin-1beta.
OBJECTIVE
Plasminogen activator inhibitor-2 (PAI-2) is an important counter proteolysis factor which helps protect tissues from inflammatory stress. The expression of PAI-2 can be modulated by various inflammatory stimulants and mediators. The aim of the present study was to investigate how serum factors, might modulate the effects of lipopolysaccharide (LPS) and interleukin-1beta on PAI-2 production by human gingival fibroblasts.


METHODS
Human gingival fibroblasts were exposed to LPS derived from Actinobacillus actinomycetemcomitans or Escherichia coli and a commercial source of interleukin-1beta (IL-1beta). The expression of PAI-2 and its mRNA was monitored by Western blotting, RT-PCR, and Northern blotting.


RESULTS
The results showed that the distribution of PAI-2 synthesised by human gingival fibroblasts (HGF) was mostly as an intracellular protein (47kDa). The presence of serum in the culture media was absolutely necessary for both the secretion of PAI-2 and for the effect of the inflammatory mediators (LPS and IL-1beta). A pattern of PAI-2 response in HGF after LPS stimulation was detected with a quick up-regulation of the PAI-2 mRNA, which was down regulated when extracellular PAI-2 (60kDa mass) levels reached plateau levels. The synthesis of PAI-2 by HGF, in terms of mRNA expression and protein synthesis, was more sensitive to stimulation with lower concentrations of LPS (10 ng/ml) than with higher LPS concentrations.


CONCLUSIONS
PAI-2 is a serum dependent molecule with major cytosolic localisation in HGF. Its cellular accumulation and secretion can be modulated by bacterial LPS and IL-1beta through serum factors.
Xiao
Y
Y
School of Dentistry, The University of Queensland, Brisbane, Australia.
Bartold
P M
PM
D000704:Analysis of Variance; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D002417:Cattle; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D004305:Dose-Response Relationship, Drug; D005312:Fetal Blood / Q000502:physiology*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation; D005881:Gingiva / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D017396:Plasminogen Activator Inhibitor 2 / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation
D017077:Culture Media, Conditioned; D007375:Interleukin-1; D008070:Lipopolysaccharides; D017396:Plasminogen Activator Inhibitor 2