QUANTITATIVE ASSESSMENT OF INFLAMMATORY CYTOKINE GENE-EXPRESSION IN CHRONIC ADULT PERIODONTITIS

Adult periodontitis is a chronic destructive disease characterized by an interaction between gram-negative bacteria and the host inflammator y response. Microbial substances such as lipopolysaccharide can activa te host cells, e.g., macrophages, fibroblasts and keratinocytes, to se crete proinflammatory cytokines including tumor necrosis factor alpha and interleukin 1 beta (IL-1 beta). This study examined the hypothesis that periodontitis tissue contains increased levels of cytokines that promote osseous and connective tissue destruction. To test this hypot hesis, diseased and healthy gingival biopsies were examined for differ ences in the expression of cytokine mRNA for the pro-inflammatory cyto kines tumor necrosis factor a and IL-1 beta and the anti-inflammatory cytokine IL-1ra using quantitative reverse transcriptase polymerase ch ain reaction and in situ hybridization methods. The levels of tumor ne crosis factor alpha and IL-1ra mRNA were shown to be significantly hig her in diseased than healthy tissues. Additionally, a significantly co rrelated expression of IL-1 beta and IL-1ra mRNA was seen in all tissu e examined. Analysis of tissue sections by immunohistochemical and in situ hybridization techniques revealed a mononuclear cell infiltrate t hat consisted of a higher average number of cells staining positive fo r tumor necrosis factor a mRNA, CD14, and CD3 in the diseased than hea lthy tissues. Although both diseased and healthy tissues expressed IL- 1 beta and IL-1ra mRNA in the epithelium, the diseased tissue biopsies expressed more IL-1 beta and IL-1ra mRNA in the connective tissue. Th ese results implicate the potential involvement of both the pro-and an ti-inflammatory cytokines in the regulation of the chronic inflammator y disease adult periodontitis.