Quantification of tryptase-TIM-3 double-positive mast cells in human chronic periodontitis

Objectives: Mast cells (MCs) are implicated in the pathogenesis of allergic reactions and inflammatory conditions through the release of inflammatory mediators. So far limited attention has been given to the role of MCs in periodontitis. T cell immunoglobulin mucin domain (TIM)-3 is an immunomodulatory molecule and influences MC function. However, whether TIM-3 is expressed on MCs in the process of human periodontal disease has not been reported. Therefore, we identified MCs by toluidine blue staining and examined the expression of TIM-3 on tryptase-positive MCs in different severities of human chronic periodontitis using double-immunofluorescence staining in this study.

Material and methods: A total of 83 human periodontal specimens were involved in this study, including healthy control tissues (n=25), chronic moderate periodontitis (n=28), and chronic severe periodontitis (n=30). The gingival specimens were fixed in 10% buffered formalin, stained with haematoxylin and eosin for histopathology, with toluidine blue for MCs, and with double-immunofluorescence for identification of tryptase-TIM-3 double-positive MCs in gingival tissues.

Results: Compared with healthy controls, the score of gingival tissue inflammation was significantly increased in the chronic moderate periodontitis (P=0.013) and chronic severe periodontitis (P<0.0001), and the densities (cells/mm(2)) of tryptase-TIM-3 double-positive MCs were significantly increased in both the chronic moderate (P=0.011) and severe periodontitis groups (P<0.0001). However, compared with the chronic moderate periodontitis group, both the score of gingival tissue inflammation (P=0.012) and the density of tryptase-TIM-3 double-positive MCs (P=0.011) in gingival tissue were significantly increased in the severe periodontitis groups.

Conclusion: Significantly increased number of tryptase-TIM-3 double-positive MCs had the similar tendency as the severity of periodontitis inflammation in human chronic periodontitis. Our data suggest that TIM-3 may have a role on MCs in human chronic periodontitis.