Immunopathogenesis Of Mast Cells Accumulation And Degranulation In Human Periodontitis

Background and objectivePeriodontal disease refers to the inflammatory processes that occur in thetissues surrounding the teeth in response to bacterial accumulations，which arecharacterized by the destruction of tooth-supporting tissue, including the gingiva,alveolar bone and the teeth themselves, finally leading to the tooth loss. Mast cells aretissue resident immune cells that participate in a variety of allergic and inflammatoryprocesses. Limited attention has been paid to the role of mast cells in periodontaldiseases. and the effects of mast cell degranulation at the chronic stages ofnon-allergic inflammation, particularly in periodontitis, are not known. The presentstudy was undertaken to analyze the relationship between the mast cell degranulationand human periodontal disease severity. In our study, results from this study willprovide valuable insight into the role of immunopathogenesis of mast cellsaccumulation and degranulation in human periodontitis.MethodsA total of60donors included mild periodontitis group (n=15), moderateperiodontitis group (n=15), advanced periodontitis group (n=15) and healthy controltissues (n=15). The specimens were stained with HE for histopathology, withtoluidine blue for identifying mast cells accumulation and degranulation, and withimmunohistochemistry for identifying the mast cell subtypes and calculating thenumber of mast cells and degranulation rate in periodontal tissue.Results1. Histological observations:1) compared to healthy controls, the specimens ofperiodontitis groups showed an intense inflammatory infiltration;2) the score ofpathology inflammatory severity was signigicantly higher in advanced periodontitisgroup than that in mild and moderate periodontitis group（P <0.01).2. Toluidine blue staining results:1) compared to healthy controls, there weresignificantly higher densities of both total and degranulated mast cells in human periodontitis groups（P <0.01）;2) the number and the percentage of degranulatedmast cells were signigicantly higher in advanced periodontitis group than tthat in mildand moderate periodontitis group（P <0.01).3. Immunohistochemical staining results:1) compared to healthy controls, agreater number of tryptase-positive mast cells and the higher densities oftryptase-positive mast cells were observed in periodontitis group;2) the number andthe percentage of degranulated tryptase-positive mast cells were signigicantly higherin advanced periodontitis group than that in mild and moderate periodontitis group（P<0.01);3) there were only a few chymase-positive mast cells observed in periodontitisgroups.4. There was a close correlation among the percentage of degranulated mastcells, the densities of tryptase-positive mast cells and the severity of humanperiodontitis.Conclusions1. In human periodontitis, the numbers of both total and degranulated mast cellwere increased with the severity of chronic periodontitis.2. The major mast cell subtype is mucosal mast cells in human periodontitis.Immunohistochemical staining is a highly efficient and simple method for identifyingthe subtypes of mast cells.3. Mast cells accumulation and degranulation may play a key role in theprogression of chronic periodontitis.