Abstract
Chronic periodontitis is a major dental disease associated with continuous inflammation and the mediation of cytokines and chemokines such as Interleukin (IL)-8. Periodontitis processes may also be associated with quantitative changes in IL-8 gene expression. We examined the transcriptional activation and mediation of a novel single nucleotide polymorphism (SNP) at position -845 (from the transcription initiation site) of the IL8 promoter. Moreover, we investigated whether the frequencies of this SNP were associated with susceptibility to chronic periodontitis among Japanese. The fragments of cloned IL8 promoter (-866 to +30) containing the novel SNP (-845T and -845C) were ligated to the luciferase gene. A luciferase assay was then conducted using these reporter plasmids in SCCTM cells. The presence and molecular weight of the -845T-specific binding proteins were analyzed by gel mobility shift and UV-crosslinking competition assays, respectively. SNP analysis was performed with DNA from 56 control subjects and 52 patients by a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method and disease associations were analyzed by a Chi-square test. These results indicate that transcriptional activity of the IL8 promoter containing -845T was approximately 9-fold higher than when the promoter contained -845C. -845T-specific binding proteins (approximately 55 and 60 kDa) were present in SCCTM cells. Genotype frequencies (T/T and T/C) between the control and patient groups were not significantly different (P = 0.586). These results suggest that transcription of the IL8 gene, particularly mediation of -845T/C, appears to be strictly regulated. This SNP was not associated with chronic periodontitis in the Japanese population.
