Immune mechanisms in periodontitis � effect of IL-4 gene polymorphisms on cytokine production

Abstract

Introduction: Periodontitis is a chronic inflammatory disease of the teeth-supporting tissues in which genetic predisposition, dental plaque bacteria and immune mechanisms play important roles. The aim of this study was to assess the influence of IL-4 gene polymorphisms on cytokine production Methods: Cytokine production (IL-1alpha, IL-1beta, IL-4, IL-5, IL-6, IL-8 , IL-10, TNF–alpha, INF–gamma) was studied after in vitro stimulation of isolated peripheral blood mononuclear cells (PBMC) by mitogens and dental plaque bacteria (Aggregatibacter actinomycetemcomitans, Escherichia coli, Tannerrella forsythensis, Porphyromonas gingivalis and Heat Shock Protein 60). Cytokine production was detected by multiplex cytokine analysis system Luminex. The results were correlated with IL-4 genotypes in patients with chronic periodontitis (CP) and healthy controls. Results: We found that mononuclear cells isolated from peripheral blood of CP patients with investigated IL-4 polymorphisms (-589C/T, -33C/T, VNTR in intron 3) significantly changed production of IFN-gamma, IL-10, IL-1alpha and IL-1beta, TNF-alpha, IL-10, MCP-1, IL-6 after stimulation by all selected bacteria and HSP (p<0.05). Conclusion: In patients with CP, IL-4 polymorphisms may influence the function of mononuclear cells to produce not only IL-4 but also other cytokines. The results of this study support Seymour’s hypothesis (1999) about the role of TH2 produced cytokines such as IL-4 in genetic predisposition to chronic periodontitis.