Expression of Epithelial-Mesenchymal Transition Associated Markers in Peri-implant Tissues

Peri-implantitis is an inflammation of bacterial etiology characterized by inflammation of mucous membranes and bone loss around the dental implant. A specific dental plaque bacteria could stimulate host cells, including the junctional epithelium, to secrete a range of pro-inflammatory cytokines involved in initiating the epithelial-mesenchymal transition (EMT) process. EMT has been described as the transdifferentiation of epithelial cells into motile mesenchymal cells. Moreover, cytokines and bacterial products have been highlighted as EMT-predisposing factors. The EMT process could render epithelial cells to lose their cell-cell adhesion and cell polarity that lend these cells to lose their function as an integrated epithelial barrier. E-cadherin is a calcium-dependent cell adhesion molecule that establishes cell-cell adhesion that plays a critical role in maintaining a barrier function in the human epithelium, including gingiva. The loss of E-cadherin is one of the most common biological indicators for EMT. In contrast, vimentin is an intermediate filament expressed in mesenchymal cells and is a canonical marker for EMT, which also promotes cell motility and an invasive phenotype. It is largely reported that EMT is regulated by various transcriptional factors such as Snail Family Transcriptional Repressor SNAIL1 and SNAIL2, zinc-finger E-box-binding (ZEB)1 and ZEB2 and TWIST transcription factors that suppress epithelial marker genes, and activate genes related with the mesenchymal phenotype. Recently, in vivo study has investigated the level of EMT markers in the gingival tissues of periodontitis patients. It was found that the expression of E-cadherin was downregulated while vimentin expression was upregulated. Despite the similarities and differences between the pathogenesis of periodontal and peri-implant diseases, the role of dental biofilm in the etiopathogenesis of the aforementioned diseases was studied largely. While it is now accepted that EMT may potentially play a role in periodontal disease pathogenicity, the possible role of EMT in the disintegration of the peri-implant epithelial barrier and the pathogenesis of peri-implant disease has not yet been investigated.