Formation of periodontal pocket by cadmium exposure - Induction of KGF by cadmium in tobacco -

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The cadmium (Cd, as CdCl_2) sensitivity of human-derived gingival fibroblasts (GF cells) and gingival keratinocytes (GK cells) was studied by cultivating in media containing Cd, and assessing the effects of the Cd on the cells using an MTT assay and DNA synthesis. The results of the MTT assay revealed there were no clear differences between any of the Cd groups (10^<-8> mM to 10 mM) and the control group for either type of cell. DNA synthesis was inhibited at Cd concentrations of 10^<-6> mM and above, although there were differences in the degree of inhibition between the two types of cells. Under the above conditions, IL-6 and IL-8 were induced at a Cd concentration of 10^<-3> mM in GF cells, while in GK cells slight inhibition was observed. This result suggests that GF cells and GK cells have different cellular responses to Cd. In contrast to this, induction of the above cytokines was not observed at any Cd concentration in GK cells. These findings indicate that the cellular responses of GF and GK cells to Cd are different. In GF cells, it was found that apoptosis was induced in 10% to 20% of cells exposed to 10^<-2> to 10^<-4> mM Cd for 48 hours. The production of KGF-1 in GF cells exposed to Cd (10^<-3> mM), IL-6 (20 ng/mL), or LPS (E. coli, 0.1 g/mL) for 24 hours was also studied. KGF-1 could not be detected in control group cells, however, KGF-1 production was detected in treated cells. The highest concentration was observed in the Cd group, followed by the IL-6 group, and finally the LPS group.Based on the above results, it is believed that Cd contained in cigarettes injures gingival cells and contributes to the formation of periodontal pockets.