Abstract:
Periodontal disease is a chronic inflammatory disease of tooth supporting structures, which comprises of gingivitis and periodontitis. Gingivitis is predominated by T cells, whereas periodontitis is a B-cell dominated lesion. The shift of a T-cell lesion to a B-cell lesion was proposed to be pathogenesis of periodontal disease. Recently, novel subpopulations of T cells and tissue-resident memory T cells (CD103+ T cells) were reported in several diseases and possibly involved in their pathogenesis. However, study of these populations in periodontal tissues is limited. The aim of this study is to investigate the presence of novel T cell subsets in periodontal tissues. Periodontal tissues obtained from either individuals with severe chronic periodontitis or clinically healthy subjects were prepared as paraffin sections and then analyzed for CD3+, CD4+, CD8+ and CD103+ T cells by immunohistochemistry. Single cell suspensions were used to analyze T cell populations using 6-color flow cytometry. From immunohistochemical analysis, CD103+ T cells were detected in both epithelium and connective tissues. Flow cytometric analysis revealed that the majority of CD103 expressing cells were CD8+ T cells. CD8+CD103+ T cells in periodontitis tissues were 2-fold higher than those of healthy periodontal tissues (58.32±26.08% and 32.70±10.90% of total CD8+ T cells, p<0.05, respectively). The study also investigated other subsets of T cells in periodontal tissues i.e. naïve (TN), stem cell-like memory (TSCM), central memory (TCM), effector memory (TEM) and terminally differentiated effector memory T (TTE) cells. Our finding showed that these 5 novel populations were detected in both healthy and periodontitis groups. However, the majority of T cell populations were TCM cells. This is the first time that showed the existence of these T cell subsets in periodontal tissues. Further studies are required to gain an insight into their role on periodontal homeostasis or pathogenesis.
