In vitro suppression of transforming growth factor-beta induced stimulation of glycosaminoglycan synthesis by acetylsalicylic acid and its reversal by misoprostol.
OBJECTIVE
To determine if acetylsalicylic acid (ASA) suppresses the stimulatory effects of transforming growth factor-beta (TGF-beta) and insulin-like growth factor-1 (IGF-1) on glycosaminoglycan (GAG) synthesis by cultured bovine articular chondrocytes (BAC), and whether such a suppression can be counteracted by the addition of misoprostol, a prostaglandin (PG) E1 analog.


METHODS
Confluent cultures of BAC were pre-incubated for 2 days with ASA (Aspirin) (250 microg/ml), TGF-beta (10 ng/ml), IGF-1 (150 ng/ml), and misoprostol (80 ng/ml), separately and in different combinations, and for 2 more days with fresh medium and the same test agents in the presence of 35S-sulfate (10 microCi/ml). The radiolabelled GAG in the medium were then isolated, separated by cellulose acetate electrophoresis, and assayed for incorporated radioactivity, as a measure of GAG synthesis.


RESULTS
TGF-beta, IGF-1, at their optimal concentrations, and misoprostol (80 ng/ml) stimulated GAG synthesis 2.6, 1.8, and 2.4-fold, respectively, of the control value, but ASA (250 microg/ml) showed no significant effect. ASA in combination with TGF-beta or misoprostol markedly suppressed the stimulation of GAG synthesis observed with either TGF-beta or misoprostol alone, but had no effect on the stimulation of GAG synthesis by IGF-1. Addition of misoprostol together with TGF-beta potentiated the stimulation of GAG synthesis by TGF-beta and abolished the suppressive effect of ASA on the stimulation of GAG synthesis by TGF-beta. Also, the magnitude of the stimulatory effect of misoprostol varied from batch to batch of misoprostol as well as for the same batch when it was added to the cultures either directly or after diluting with serum-free medium.


CONCLUSIONS
In BAC cultures, ASA suppresses and misoprostol potentiates the stimulation of GAG synthesis by TGF-beta. Misoprostol also counteracts ASA induced suppression of the stimulation of GAG synthesis by TGF-beta.
Anastassiades
T
T
Department of Medicine, Queen's University, Kingston, Ontario, Canada.
Chopra
R
R
Law
C
C
Wong
E
E
D000818:Animals; D001241:Aspirin / Q000494:pharmacology*; D002358:Cartilage, Articular / Q000187:drug effects / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects* / Q000378:metabolism; D006025:Glycosaminoglycans / Q000096:biosynthesis*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D016595:Misoprostol / Q000494:pharmacology*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D006025:Glycosaminoglycans; D016212:Transforming Growth Factor beta; D016595:Misoprostol; D007334:Insulin-Like Growth Factor I; D001241:Aspirin