CYTOKINE MESSENGER-RNA EXPRESSION IN CHRONIC INFLAMMATORY PERIODONTAL-DISEASE

It has previously been reported that, in periodontitis lesions, T cell s with a memory/activated phenotype and with a type 2 cytokine profile accumulate in an oligoclonal fashion. Delineation of the role of cyto kines in periodontal inflammation has, however, been complicated becau se of cross-regulation and because of their overlapping and often redu ndant effects. The aim of this study was to examine messenger RNA leve ls for interferon gamma, interleukin 4 (IL-4), IL-10, IL-12 and IL-13 in gingival tissues and peripheral blood mononuclear cells of patients with adult periodontitis. Reverse transcription polymerase chain reac tion and subsequent image analysis was used to determine the level of mRNA for each cytokine. The mean expression of interferon gamma mRNA w as significantly higher in peripheral blood mononuclear cells than in gingival tissues. In contrast, the mean expression of IL-10 mRNA was h igher in gingival tissues than in peripheral blood mononuclear cells. This high expression of IL-IO mRNA was, in fact, seen in only 7 gingiv al tissue samples with the majority of samples showing levels similar to peripheral blood mononuclear cells. There was no difference in the mean expression of IL-12 p35 mRNA between gingival tissues and periphe ral blood mononuclear cells. However, IL-12 p40 mRNA was expressed hig her in gingival tissues than in peripheral blood mononuclear cells in 6 out of 16 samples with significant difference of mean expression. Li ke IL-10, gingival tissue samples and peripheral blood mononuclear cel ls expressed similar levels of IL-12 p40 mRNA. There was no difference in the mean expression of IL-13 in gingival tissues and peripheral bl ood mononuclear cells. Nevertheless, more peripheral blood mononuclear cell samples demonstrated high IL-13 mRNA expression than gingival ti ssue samples. IL-4 mRNA was weak but detectable in 3 gingival tissue s amples. These results support the concept that cytokines form complex networks in periodontitis lesions and that their overlapping and redun dant effects should be taken into account when considering the patholo gy of inflammatory periodontal disease. Dichotomous expression of IL-1 0 and IL-12 p40 mRNA in the periodontal lesion may be associated with disease entity.