The presence, function and regulation of IL-17 and Th17 cells in periodontitis

Periodontitis (PD) is a chronic inflammatory disease characterised by tissue inflammation and destruction of the associated alveolar bone. It is caused by the colonisation of the bacterial plaque biofilm and the resultant host immune responses in the surrounding periodontal tissues. The pro-inflammatory cytokine IL-17, and IL-17 producing CD4+ T cells (also called Th17 cells) have been shown to play an important role in many inflammatory diseases. There is increasing evidence of the presence of IL-17 and Th17 cells in human PD lesions and this may be associated with disease severity. Moreover, several animal studies indicate the potential role of IL-17 and Th17 cells in gingival inflammation and the resultant bone destruction in PD. Here we review recent findings regarding the presence, function and regulation of IL-17 and Th17 cells in PD, and we highlight potential areas of future research interest.