Combined effects of proinflammatory cytokines and intermittent cyclic mechanical strain in inhibiting osteogenicity in human periodontal ligament cells.

Mechanical strain plays an important role in bone formation and resorption during orthodontic tooth movement. The mechanism has not been fully studied, and the process becomes complex with increased amounts of periodontal patients seeking orthodontic care. Our aims were to elucidate the combined effects of proinflammatory cytokines and intermittent cyclic strain (ICS) on the osteogenic capacity of human periodontal ligament cells. Cultured human periodontal ligament cells were exposed to proinflammatory cytokines (interleukin-1ß 5 ng/mL and tumor necrosis factor-α 10 ng/mL) for 1 and 5 days, and ICS (0.5 Hz, 12% elongation) was applied for 4 h per day. The autocrine of inflammatory cytokines was measured by enzyme-linked immunosorbent assay. The expression of osteoblast markers runt-related transcription factor 2 and rabbit collagen type I was determined using real-time polymerase chain reaction and Western blot. The osteogenic capacity was also detected by alkaline phosphatase (ALP) staining, ALP activity, and alizarin red staining. We demonstrated that ICS impaired the osteogenic capacity of human periodontal ligament cells when incubated with proinflammatory cytokines, as evidenced by the low expression of ALP staining, low ALP activity, reduced alizarin red staining, and reduced osteoblast markers. These data, for the first time, suggest that ICS has a negative effect on the inductive inhibition of osteogenicity in human PDL cells mediated by proinflammatory cytokines.

Mast cell degranulation in human periodontitis.

BACKGROUND: Mast cells are tissue-resident immune cells that participate in a variety of allergic and inflammatory conditions. Limited attention has been given to the role of mast cells in periodontal diseases, and the effects of mast cell degranulation on the chronic stages of non-allergic inflammation, particularly in periodontitis, are not known. The present study analyzes the relationship between the mast cell degranulation and human periodontal disease progression. METHODS: A total of 50 clinical specimens including moderate periodontitis (n = 17), advanced periodontitis (n = 18), and healthy control tissues (n = 15) were used in this study. All specimens were fixed in 10% buffered formalin and stained with hematoxylin and eosin for histopathology, with toluidine blue for identifying mast cells, and by immunohistochemistry for the expressions of mast cell tryptase in periodontal tissues. The total and degranulated mast cell densities (per high-power field) were quantified in the specimens. RESULTS: Compared with healthy controls, there were significantly increased both total and degranulated mast cell densities in human moderate (P <0.01) and advanced (P <0.01) periodontitis groups by toluidine blue staining, and there were significantly higher densities of both total and degranulated tryptase-positive mast cell subpopulation in the moderate periodontitis group (P <0.01) and even significantly higher subpopulation densities in the advanced periodontitis group by immunohistochemical staining, in which both total and degranulated mast cell densities were significantly higher in the advanced periodontitis group than those in the moderate periodontitis group (P <0.01) by both toluidine blue staining and immunohistochemical staining. There was significantly more severe periodontal inflammatory pathology in the advanced periodontitis group than in the moderate periodontitis group (P <0.01). CONCLUSION: These findings indicate a significant correlation among tryptase-positive mast cell density, the degree of their degranulation, and the human periodontitis severity, and the results of this study further indicate that mast cell degranulation appears to be associated with human periodontal disease.

Correlation of levels of interleukin-1ß in gingival crevicular fluid to the clinical parameters of chronic periodontitis.

BACKGROUND AND OBJECTIVES: IL-1ß is a potent stimulator of bone resorption and has been implicated in the pathogenesis of periodontal destruction. Therefore, this study was designed to compare the levels of IL-1ß of chronic periodontitis patients with the healthy subjects. Another objective of this study was to correlate IL-1ß levels with the clinical parameters of the periodontal disease progression. METHODS: For this study, total 60 subjects were chosen (30- healthy and 30-chronic periodontitis). Simplified oral hygiene index (OHI-S), gingival index (GI), periodontal disease index (PDI), probing depth (PD), tooth mobility, bleeding on probing (BOP) were recorded for all the subject. Gingival crevicular fluid (GCF) was collected and subjected for ELISA for estimation of IL-1ß. RESULTS: At the periodontal diseased sites, the IL-1ß levels increased at least 2-fold as compared with healthy subjects. This increase was highly significant (p = 0.0000). Within the test group, IL-1ß levels correlated positively and significantly with PDI, PD, BOP and tooth mobility. The correlations of IL-1ß with PD (p = 0.000) and IL-1ß with BOP (p = 0.0004) were highly significant. INTERPRETATION AND CONCLUSION: These data suggest that amount of GCF IL-1ß is closely associated with periodontal status. This relationship may be valuable in monitoring periodontal disease activity. CLINICAL SIGNIFICANCE: It could be stated from this study on IL- 1ß that there seem to be a strong correlation between periodontal tissue destruction and IL-1ß. Furthermore IL-1ß level could also differentiate between active and inactive periodontal lesions.

Antibody responses to suspected periodontal pathogens in elderly subjects with periodontal disease.

Little is known about the relationship of aging to periodontal disease. The immune response undergoes aging-related changes resulting in loss of functional capacity. The aim of this study was to investigate the relationship between levels of serum IgG antibodies against suspected periodontal pathogenic microorganisms to the presence or absence of periodontal disease in an elderly (65-75 yrs) population. From this study, we obtained information concerning: (1) the ability to differentiate elderly individuals without disease from those with disease by their levels of antibodies against periodontal pathogens and (2) which periodontal pathogen(s) triggered those responses. IgG anti- Porphyromonas gingivalis (strains W83 and 381) levels in the serum of elderly patients with severe periodontal disease were the only antibody responses measured which were elevated compared to the elderly control group of subjects with no periodontal disease. Anti- Prevotella intermedia IgG levels in both elderly patient groups were depressed compared to anti- P. intermedia levels in the young normal control subjects. Serum IgG antibody levels to six other plaque microorganisms did not differentiate between diseased and normal, elderly or young subjects. This data suggested that P. gingivalis was associated with periodontal disease in this elderly group of individuals and that those elderly individuals were able to respond with a normal IgG immune response.

Macrophage chemotaxis in experimental tooth movement in the rat.

Extracts from tissue surrounding teeth being moved contained chemotactic activity for peritoneal exudate cells (PEC). The tissue was homogenized, extracted and diafiltered using a 100,000 mol. wt cut-off filter. The filtrate contained statistically-significant chemotactic activity, whereas the retentate did not. Further fractionation of the filtrate using an isoelectric focusing column produced a filtrate fraction in the pH range between 5.0 and 6.8 which was chemotactically active. This sample was analysed for purity and mol. wt using sodium dodecylsulphate polyacrylamide-gradient gel electrophoresis (SDS-PAGE). Gels of the active fraction stained with Coomassie blue showed two distinct bands with molecular weights of 69,000 and 60,000.