TNF-α and IL-6 Regulate Leucine-rich α2 Glycoprotein and Heat Shock Protein 70 Levels in Human Gingival Epithelial Ca9 - 22 Cells

Abstract

Leucine-rich α2 glycoprotein（LRG）, C-reactive protein（CRP）and heat shock proteins （HSPs）are inflammation-related proteins which accurately reflect disease activities and degree of tissue damage. Tumor necrosis factor-α（TNF-α）, interleukin-6（I L -6）and in terleukin-1β（IL-1β）are typical inflammatory cytokines that increase in periodontitis. Junctional epithelium （JE）lies immediately apical to the base of the pocket, and attaches to the enamel surface with hemidesmosomes. To analyze changes in the expressions of LRG, CRP and HSP70 mRNA and protein in inflamed periodontitis tissues, especially in the JE, human gingival epithelial Ca9-22 cells were treated with TNF-α（10 ng/ml）, IL-6（10 ng/ml）or IL-1β（1 ng/ml）to induce an inflammatory state. Total protein and RNA were extracted, and Western blot and real-time PCR were performed. Cytotoxic lactate dehydrogenase（LDH）assays were used to analyze the cytotoxicity of TNF-α, IL-6 or IL-1β on Ca9-22 cells. Cytotoxicity was detected for TNF-α, IL-6 and IL-1β a t 12 h, with the highest cytotoxicity at 24 h. IL-1β decreased LRG and HSP70 mRNA and protein levels at 12 h and 24 h. TNF-α increased LRG mRNA and protein levels at 12 h and suppressed HSP70 mRNA and protein levels at 24 h. IL-6 increased LRG mRNA and protein levels at 12 h and decreased HSP70 mRNA and protein levels at 12 h. These results suggest that TNF-α and IL-6 could be involved in the onset and progression of periodontitis by regulating the expression levels of LRG and HSP70 in the JE.