ENDOTOXIN, TUMOR-NECROSIS-FACTOR, AND DEXAMETHASONE EFFECTS ON HUMAN ENDOTHELIAL-CELL FIBRONECTIN DYNAMICS - SYNTHESIS, MATRIX ASSEMBLY, AND RECEPTOR EXPRESSION

The three inflammatory modulators endotoxin, tumor necrosis factor (TN F) alpha, and dexamethasone (DEX) were studied for their effects on fi bronectin (FN) dynamics in human umbilical vein endothelial cells. Cel l culture supernatants were analyzed for new soluble pool FN synthesis . Endotoxin (LPS) (10 mu g/mL) decreased the newly synthesized soluble pool of FN (p < 0.05). An increase in soluble FN was demonstrated wit h 1 and 10 ng/mL TNF alpha (p < 0.05). DEX decreased newly synthesized endothelial cell (EC) FN in the soluble pool at 4, 40, and 400 mu g/m L (p < 0.05). Extracellular matrix FN content was examined using immun ofluorescence. The thick FN mesh seen in control cells contrasted with a decreased FN matrix after treatment with each of the three study ag ents. Immunoprecipitation of the FN receptor alpha(5) beta(1) integrin from [S-35]methionine-labelled cell extracts demonstrated down regula tion of receptor expression by both TNF a and DEX as compared with con trol samples. These data indicate that LPS, TNF alpha and DEX may weak en EC-substratum adhesion by differential effects on FN synthesis and secretion, FN incorporation into the extracellular matrix, and down re gulation of FN receptor expression.