Production of IL-6 and IL-8 in human fibroblasts stimulated with bacterial toxins

ABSTRACT

Cytokines are hormone-like proteins which mediate and regulate inflammatory and immune responses. Interleukin-6 (IL-6) is involved in the final differentiation of B cells into antibody-producing cells. Interleukin-8 (IL-8) is a neutrophil chemotactic factor that plays an important role in the recruitment of neutrophils to inflammatory loci. Inflammatory mediators produced by cells in the gingiva have been implicated in the initiation and progression of periodontitis and oral infection. The purpose of this study was conducted to investigate the effect of lipopolysaccharide (LPS), Staphylococcus enterotoxin B (SEB) on production of IL-6 and IL-8 by human gingival and facial dermal fibroblasts. Primary cultured human gingival and facial dermal fibroblasts were incubated with LPS (0.01, 0.1, 1.0 microgram/ml), SEB (0.01, 0.1, 1.0 microgram/ml) or LPS (0.1 microgram/ml) plus SEB (0.1 microgram/ml). Culture supernatants were collected at 24, 48, and 72 hrs and assessed for IL-6 and IL-8 production by enzyme-linked immunosorbent assay. IL-6 production in gingival fibroblasts stimulated with LPS was higher than that with SEB. IL-6 production by double exposure with LPS plus SEB was amplified in comparison with single exposure of LPS or SEB. IL-6 production in facial dermal fibroblasts was increased only by stimulation with a high concentration of LPS (1.0 microgram/ml). Its production in facial dermal fibroblasts by exposure with SEB was decreased in comparison with control, nontreated cells. Therefore, gingival fibroblasts showed higher sensitivity than facial dermal fibroblasts in response to low concentration of LPS. Also, IL-6 production by double exposure with LPS plus SEB was amplified in comparison with single exposure of LPS or SEB. IL-8 production in gingival fibroblasts was enhanced greatly only by stimulation of high concentration of LPS (1.0 microgram/ml). That by exposure with SEB was increased only in 24 hrs cultivation. IL-8 production by double exposure with LPS plus SEB was amplified in comparison with single exposure of LPS or SEB. IL-8 production in facial dermal fibroblasts was decreased by LPS and increased only in 48 hrs cultivation by SEB. IL-8 production by double exposure with LPS plus SEB was enhanced only in 48 hrs cultivation in comparison with single exposure of LPS or SEB. Therefore, IL-6 and IL-8 production were released at various quantities according to bacterial toxin applied and site of fibroblast harvested.These results suggest that gingival fibroblasts may be concerned with IL-6 and IL-8 related inflammatory response more than facial dermal fibroblasts.