DIFFERENTIAL EFFECTS OF TRANSFORMING GROWTH FACTOR-±1 ON LIPOPOLYSACCHARIDE INDUCTION OF ENDOTHELIAL ADHESION MOLECULES

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Abstract
In this report, we studied the effects of transforming growth factor (TGF)-beta 1 on lipopolysaccharide (LPS)-induced expression of endothelial cell (EC) adhesion molecules. Confluent human umbilical cord vein EC cultures were stimulated with Escherichia coli LPS and TGF-beta 1, alone or in combination for various times and evaluated for expression of ICAM-1, E-selectin, and VCAM-1 by immunofluorescence and radioimmunoassay. Effects of LPS and/or TGF-beta 1 on cell growth were also studied by 3H-thymidine incorporation. Both LPS and TGF-beta 1 alone stimulated EC expression of the adhesion molecules in a dose-dependent manner. The effects of TGF-beta 1 on LPS induction of the adhesion molecules varied with LPS concentration and treatment time, mode, and duration. Pretreatment with TGF-beta 1 for 24 h greatly augmented LPS induction of ICAM-1 and VCAM-1 expression, but decreased E-selectin expression. TGF-beta 1 also enhanced expression of the adhesion molecules in cells that were pretreated with 1 microgram/mL LPS for 60 min. Concomitant treatment with TGF-beta 1/LPS resulted in significant increases in ICAM-1 but decreases in VCAM-1 expression. TGF-beta 1 effects on LPS induction of the adhesion molecules were more prominent at lower LPS levels (.001, .01 microgram/mL). Both LPS and TGF-beta 1 suppressed thymidine incorporation in a dose-related pattern. These data suggest that TGF-beta 1 has additive and antagonistic effects on LPS induction of the adhesion molecules and that the cell responsiveness to the stimuli in the expression is related to growth condition of the cells. In conclusion, our findings suggest that TGF-beta 1 exhibits pro-inflammatory and anti-inflammatory activities in human endothelial cells and may play an important role in regulating leukocyte adherence and extravasation under LPS-induced inflammatory conditions.

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