FoxP3+ regulatory T cells, interleukin 17 and mast cells in chronic inflammatory periodontal disease

Background and Objective T cells are known to play a pivotal role in periodontal disease; however, less is known about the T‐helper subsets of regulatory T cells (Tregs) and Th17 cells. The aim of this study was to investigate the cell types expressing FoxP3 and interleukin ( IL )‐17A within periodontal disease tissues and to determine gene and protein expression profiles associated with periodontitis. Material and Methods A total of 10 healthy/gingivitis and 10 chronic periodontitis tissues were investigated. Immunohistochemistry and immunofluorescence techniques were used to identify the FoxP3 and IL 17‐positive cells and to determine the cell types respectively. Gene expression was determined using semi‐quantitative polymerase chain reaction array technology that allowed the analysis of 84 pathway‐focused genes known to be associated with Tregs and Th17 cells. Transforming growth factor ( TGF )‐β1, IL 10 and IL 17A protein levels were determined using enzyme‐linked immunosorbent assay. Results Double immunofluorescence labeling revealed that all FoxP3 + cells were CD 4 + , while IL 17 + cells were neither CD 4 + nor CD 8 + but were tryptase + , suggestive of mast cells. More FoxP3 + cells than IL 17 + cells were found in all the tissues examined and overall there were few IL 17 + cells. Statistically significant increases in gene expression were found for STAT 5A, STAT 3, SOCS 1, TGF β1 and IL 10 in the chronic periodontitis specimens predominantly infiltrated with B cells and plasma cells when compared with healthy/gingivitis specimens predominantly infiltrated with T cells. Protein analysis demonstrated higher levels of the TGF β1 and IL 10 cytokines in periodontitis tissues and in B‐cell and plasma cell predominant gingival tissues than in healthy/gingivitis tissues and T‐cell predominant gingival tissues. IL 17A gene and protein expression was not detected in any of the tissues. Conclusion Based on the findings of this study, we suggest that the source of low levels of IL 17A in periodontal tissues is mast cells not Th17 cells and that Tregs may have a more prominent role in the pathogenesis of periodontal disease than Th17 cells.