Toll-like Receptor2and Toll-like Receptor4Expression On Mast Cells In Gingival Tissue Of Human Chronic Periodontitis

Background and objectivePeriodontal disease is an inflammatory condition affecting the tissues surroundinga tooth, and is the leading cause of tooth loss in adult. The mast cells (MCs) aretraditionally considered as the effector cells of allergic reactions. Recent studies haveshown that MCs plays an important role in the regulation of innate and adaptiveimmune response. Studies have shown that MCs were observed in the gingival tissuesof patients with chronic periodontitis, suggesting that MCs may be involved in theimmunopathogenesis of chronic periodontitis. As a kind of pathogen-associatedmolecular patterns (PAMPs) recognition receptors, Toll-like receptors (TLRs) play animportant role in the innate immune defense. As the important members of the TLRs,Toll-like receptor2(TLR2) and Toll-like receptor4(TLR4), can identify a variety ofmicroorganisms PAMPs, which mediates inflammation. Limited attention has beenpaid to the relationship of TLRs on MCs and chronic periodontitis. The present studywas aimed to observe the expression of TLR2and TLR4on MCs in the gingivaltissues of different stages of human chronic periodontitis, to analyze the role of TLR2and TLR4on MCs in the immunopathogenesis of human chronic periodontitis.MethodsA total of60donors included healthy control group (n=15), slight chronicperiodontitis group (n=15), moderate chronic periodontitis group (n=15) and severechronic periodontitis group (n=15). The gingival specimens were fixed in10%buffered formalin, stained with hematoxylin and eosin for histopathology, stained withimmunohistochemistry for identification of TLR2and TLR4in gingival tissues,stained with double-immunofluorescence for identification of tryptase-TLR2, TLR4double-positive MCs in gingival tissues, and calculating the densities (cells/mm2) oftryptase-TLR2, TLR4double-positive MCs in gingival tissues.Results1. Histological observations Compared with the healthy control, the specimens of chronic periodontitis groupsshowed an intense inflammatory infiltration, the score of gingival tissue pathologyinflammation was significantly increased in the chronic periodontitis groups (P <0.01).The score of gingival tissue pathology inflammation in moderate chronic periodontitisgroup was significantly higher than that of slight chronic periodontitis group (P<0.01). The score of gingival tissue pathology inflammation in severe chronicperiodontitis group was significantly higher than that of slight and moderate chronicperiodontitis group (P <0.01).2. Immunohistochemistry staining resultsCompared with the healthy control, both the average rate of TLR2and TLR4positive cells were significantly increased in human chronic periodontitis groups (P<0.01). Both the average rate of TLR2and TLR4in moderate chronic periodontitisgroup were significantly higher than those of the slight chronic periodontitis group (P<0.01). Both the average rate of TLR2and TLR4in severe chronic periodontitisgroup were significantly higher than those of the slight and moderate chronicperiodontitis group (P <0.01).3. Double-immunofluorescence staining resultsCompared with the healthy control, both the densities of tryptase-TLR2, TLR4double-positive MCs were significantly increased in human chronic periodontitisgroups (P <0.01). Both the densities of tryptase-TLR2, TLR4double-positive MCs inmoderate chronic periodontitis group were significantly higher than those of the slightchronic periodontitis group (P <0.01), and both the densities of tryptase-TLR2, TLR4double-positive MCs in severe chronic periodontitis group were significantly higherthan those of the slight and moderate chronic periodontitis group (P <0.01).4. The correlation of positive cells and tissue inflammation analysis resultsThe Pearson analysis showed that there was a strong correlation of the averagerate of TLR2, TLR4positive cells, the densities of tryptase-TLR2, TLR4double-positive MCs and the severity of human chronic periodontitis (P <0.01).Conclusions 1. The average rate of TLR2and TLR4positive cells in gingival tissues ofchronic periodontitis were increased with the severity of chronic periodontitis.2. The densities of tryptase-TLR2, TLR4double-positive MCs in gingivaltissues of chronic periodontitis, were increased with the severity of chronicperiodontitis.TLR2and TLR4expression on MCs may involved in chronic periodontitisinflammation. TLR2and TLR4on MCs may play a key role in the pathogenesis ofchronic periodontitis.