Background: A number of different theories have been postulated to explain the progression of gingivitis to periodontitis in the context of the Th1/Th2 paradigm. However, no consistent results have been obtained. Th17, a new T-cell subset producing IL-17, which is implicated in many aspect of inflammatory tissue destruction, overcomes many of the discrepant findings in the studies related to the Th1/Th2 hypothesis. We compared the gene expression profile of Th17-related molecules in gingivitis and periodontitis lesions showing distinct clinical entities.
Methods: Gingival tissue samples were obtained from 23 gingivitis and 24 periodontitis tissues. The gene expression was measured by using quantitative real-time PCR for IL-17A, IL-17F, CCR4, CCR6, IL-12 p35 and IL-23 p19. The difference of gene expressions between gingivitis and periodontitis was analyzed by Mann-Whitney U-test. Correlations between each gene expression were also analyzed.
Results: The expression level of IL-17A was higher than that of IL-17F and a significant difference in expression between gingivitis and periodontitis was observed only for IL-17A. CCR4 and CCR6 tended to be higher in periodontitis compared with gingivitis, although the differences were not statistically significant. Whereas the gene expression of IL-12 p35 was significantly higher in periodontitis compared with gingivitis, that of IL-23 p19 was not different between the two diseases.
Conclusion: This study demonstrates the elevated expression of IL-17 and IL-12 in periodontitis, i.e., the tissue destruction form of periodontal diseases, as compared with gingivitis, and provides new insight into the T-cell mediated immunopathogenesis of periodontal disease.