Lipopolysaccharide increases cell surface-associated fibronectin in fibroblasts in vitro

This study assessed the fibronectin expression by fibroblasts derived from noninflamed and inflamed gingiva by measuring the amount of cell surface-associated fibronectin and fibronectin released into the medium. The effects of added lipopolysaccharide from Porphyromonas gingivalis, Prevotella nigrescens and Escherichia coli on both types of fibroblasts were also studied. In the absence of lipopolysaccharide, the amounts of the two types of fibronectin were significantly larger in the fibroblasts from inflamed than from noninflamed gingiva. The specific lipopolysaccharide had no effect on the amount of fibronectin released into the medium by either fibroblast type. The amount of cell surface-associated fibronectin increased significantly when lipopolysaccharide (0.1 and 1 microgram/ml) was added to the cells from the noninflamed gingiva (the effect was evident in the order: P. gingivalis>P.nigrescens>E. coli). Lipopolysaccharide from P. gingivalis significantly increased the cell surface-associated fibronectin even at a low concentration of lipopolysaccharide (0.01 microgram/ml). In fibroblasts from the inflamed gingiva, only the lipopolysaccharide from P. gingivalis was effective in increasing the amount of cell surface-associated fibronectin. Our findings showed that the fibronectin expression was increased in the fibroblasts from inflamed gingiva and that lipopolysaccharide from P. gingivalis increased the cell surface-associated fibronectin.