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Abstract

Keratinocyte growth factor (KGF) and fibroblast growth factor-10 (FGF-10) are two highly homologous members of the fibroblast growth factor family that are expressed by fibroblast cells and are know to be paracrine mediators that induce epithelial cell proliferation in psoriasis, Crohn's disease, and ulcerative colitis. KGF expression is highly upregulated during wound healing and chronic inflammation. Periodontitis is a chronic inflammatory disease that has associated with it proliferation of the oral sulcular and junctional epithelium during disease onset. However, the KGF and FGF-10 expression in human gingival fibroblasts has not yet been confirmed by any study. Therefore, we examined the KGF and FGF-10 protein and gene expression using serum, pro-inflammatory cytokines (EL-lα, IL-iβ, IL-6, TNF-α) and drugs associated with gingival overgrowth (Cyclosporine-A (CSA), Dilantin, and Nifedipine). Northern results showed that treatment of fibroblast cells with 10.0% FBS, IL-lα, IL-β, and CSA increased KGF expression by 1.2, 1.2, 1.13, and 1.2 fold at 3 hours and by 1.6, 1.6, 1.4, and 2 fold at 6 hours, respectively. On the other hand, TNF-α and IL-6 increased the KGF expression by 1.25 and 1.2 at 3 hours but decreased to 1.16 and 1.1 at 6 hours, respectively. However, these treatments did not change FGF-10 mRNA expression levels. In addition to Northern analysis, the sandwich ELISA technique was used to investigate protein expression. Using this technique, we found that KGF protein level in human gingival fibroblasts was maximally increased by 24 hours and decreased over time, when treated with pro-inflammatory cytokines. In addition, treatment of six different gingival fibroblast cell lines (3 isolated from sites of periodontal health and 3 from chronic periodontitis) with proinflammatory cytokines and drugs associated gingival overgrowth, illustrated that pro-inflammatory cytokines and CSA treatment increased KGF protein expression in all six-cell lines similarly. However, Nifedipine and Dilantin failed to do so. Lastly, in a combination study, the presence of one cytokine with CSA induced KGF protein expression but no additive effect was found. The result of this study illustrated that the upregulation of KGF expression, may play an important role during epithelial proliferation in periodontitis and CSA associated gingival overgrowth.