| Background and objectivePeriodontal diseases are a diverse group of clinical entities in which induction of inflammation results in destruction of the attachment apparatus of the teeth resulting in loss of tooth, if left untreated. Periodontal disease is one of the most common diseases of the oral cavity and is the major cause of tooth loss in adults. The role of the host response in periodontitis is complex, which has been considered to be mediated mainly by a variety of immune cells and cytokines. It is generally accepted that dental biofilms is the primary etiologic factor for periodontal diseases. Substances released from this biofilm such as lipopolysaccharides, antigens and other virulence factors, gain access to the gingival tissue and initiate an inflammatory and immune response, leading to the activation of host defence cells. As a result of cellular activation, inflammatory mediators, including cytokines, chemokines, arachidonic acid metabolites and proteolytic enzymes collectively contribute to tissue destruction and bone resorption.Recent studies have shown that MCs plays an important role in the regulation of innate and adaptive immune response and most notably in connection with innate immune responses, wound healing, and inflammatory disease. Mediators release from degranulation of MCs cause inflammation and participate in body defense. Studies have shown that MCs were observed in the gingival tissues of both healthy and chronic periodontitis patients with increased in number and degranulated obviously in human periodontitis, tryptase is the most abundant protein constituent of the secretory granules of human MCs. The T cell immunoglobulin and mucin domain(TIM) gene family, a group of cell surface receptors, have indicated that plays a critical role in regulating immune responses. TIM-1 and TIM-3 are differentially expressed by effector Th2 and Th1 cells; TIM-1 enhances Th2 cell activation and TIM-3 down-regulates Th1 cell function. So far limited attention has been given to the immune role and the mechanism of the tryptase-TIM-1, TIM-3 double-positive MCs in the evolution of periodontal disease. The present study was aimed to observe theexpression of TIM-1 and TIM-3 on MCs in the gingival tissues of different stages of human chronic periodontitis, to analyze the role of TIM-1 and TIM-3 on MCs in the immunopathogenesis of human chronic periodontitis.MethodsA total of 80 donors included healthy control(n=20), slight chronic periodontitis group(n=20), moderate chronic periodontitis group(n=20) and severe chronic periodontitis group(n=20). The gingival specimens were fixed in 10 % buffered formalin, stained with hematoxylin and eosin for histopathology, stained with toluidine blue and immunohistochemistry for identifying mast cells accumulation and degranulation, stained with double-immunofluorescence for identification of tryptase-TIM-1, TIM-3 double-positive MCs in gingival tissues, and calculating the densities(cells/mm2) of tryptase-TIM-1, TIM-3 double-positive MCs in gingival tissues. Wilcoxon signed-rank test, Kruskal-Wallis H test, Nemenyi test, one-way ANOVA and Pearson correlation analysis, were applied for analysis using satatistical software programme(SPSS 13.0) for windows. P <0.05 was considered statistically significant.Results1. Histological observationsCompared with the healthy control, the specimens of chronic periodontitis groups showed an intense inflammatory infiltration, the score of gingival tissue pathology inflammation was significantly increased in the chronic periodontitis groups(P <0.01). The score of gingival tissue pathology inflammation in moderate chronic periodontitis group was significantly higher than that of slight chronic periodontitis group(P <0.01). The score of gingival tissue pathology inflammation in severe chronic periodontitis group was significantly higher than that of slight and moderate chronic periodontitis group(P <0.01).2. Toluidine blue and immunohistochemistry staining resultsThe positive cells in both toluidine blue staining and immunohistochemical staining were distributed roughly the same. The percentage of MCs with degranulation with immunohistochemical staining were higher than that with toluidineblue staining(P <0.05), and the degranulation phenomenon was more obvious.Compared to healthy controls, there were significantly higher percentage of both MCs and MCs with degranulation in human periodontitis groups(P <0.01). The percentage of MCs with degranulation were signigicantly higher in moderate chronic periodontitis group than that in slight periodontitis group(P <0.01). The percentage of MCs with degranulation were signigicantly higher in severe chronic periodontitis group than that in slight and moderate periodontitis group(P <0.01). 3. Double-immunofluorescence staining results Compared with the healthy control, both the densities of tryptase-TIM-1, TIM-3 double-positive MCs were significantly increased in human chronic periodontitis groups(P <0.01). Both the densities of tryptase-TIM-1, TIM-3 double-positive MCs in moderate chronic periodontitis group were significantly higher than those of the slight chronic periodontitis group(P <0.01), and both the densities of tryptase-TIM-1, TIM-3 double-positive MCs in severe chronic periodontitis group were significantly higher than those of the slight and moderate chronic periodontitis group(P <0.01).4. The correlation analysis resultsThe Pearson analysis showed that there was a strong correlation of the percentage of MCs with degranulation, the densities of tryptase-TIM-1, TIM-3 double-positive MCs and the severity of human chronic periodontitis(P <0.01).Conclusions1. The average percentage of MCs and MCs with degranulation in gingival tissues of chronic periodontitis was increased with the severity of chronic periodontitis. 2. The densities of tryptase-TIM-1, TIM-3 double-positive MCs in gingival tissues of chronic periodontitis, were increased with the severity of chronic periodontitis. 3. MCs accumulation and degranulation may play a key role in the progression of chronic periodontitis; TIM-1 and TIM-3 expression on MCs may involve in chronic periodontitis inflammation, and may play an important role in the pathogenesis of chronic periodontitis. |
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