Inducible expression of A Disintegrin and Metalloproteinase 8 in chronic periodontitis and gingival epithelial cells.

BACKGROUND AND OBJECTIVES: The expression of A Disintegrin and Metalloproteinase 8 (ADAM8) is associated with several inflammatory diseases. Elevated ADAM8 levels have been shown in gingival crevicular fluid of patients with chronic periodontitis. The objective of this study was to investigate ADAM8 expression in chronic periodontitis tissues compared with that in normal tissues. ADAM8 expression and its inductive mechanism were examined in human gingival epithelial cells (HGECs) and human gingival fibroblasts. MATERIAL AND METHODS: Total RNA and protein were extracted from gingival biopsies of 33 patients with chronic periodontitis and those of 23 healthy volunteers. ADAM8 mRNA and protein expression was analyzed by real-time polymerase chain reaction, immunoblotting and immunohistochemistry. ADAM8 expression in control and stimulated cells in the presence or absence of specific inhibitors for mitogen-activated protein kinase pathways was assayed by real-time polymerase chain reaction, immunoblotting, flow cytometry and immunofluorescence. RESULTS: ADAM8 mRNA and protein expression in chronic periodontitis tissues was significantly greater than that in normal tissues (p < 0.01). Significantly increased ADAM8 expression was detected in the gingival epithelium of chronic periodontitis tissues (p < 0.001). ADAM8 mRNA expression in HGECs, but not in human gingival fibroblasts, was significantly induced by stimulation with Fusobacterium nucleatum (p < 0.05), partially via the p44/42 mitogen-activated protein kinase pathway. ADAM8 expression in the cell lysates and on the surface of HGECs was induced by stimulation with F. nucleatum. CONCLUSION: ADAM8 expression is increased in inflamed chronic periodontitis tissues and localized within gingival epithelium, consistent with an upregulation of ADAM8 expression in F. nucleatum-stimulated HGECs, suggesting a possible role of ADAM8 in innate immunity of periodontal tissue.

Streptococcus mutans and Streptococcus sobrinus colonization and caries experience in 3- and 5-year-old Thai children.

OBJECTIVES: The aim of this study was to examine the colonization of Streptococcus mutans and Streptococcus sobrinus in supra-gingival plaque samples and to determine their correlation with the prevalence of early childhood caries (ECC) in Thai children. MATERIALS AND METHODS: A total of 344 Thai children, ages 3 and 5 years, were invited to participate in this study. Caries status of the children was examined. Supra-gingival plaque samples were collected. Quantitative real-time PCR was performed to evaluate DNA levels of S. mutans and S. sobrinus. RESULTS: Eighty-five percent of the children were colonized by S. mutans and 50.9% of them were colonized by S. sobrinus. The prevalence of ECC was 43.8% and 56.2% among 3- and 5-year-old children, respectively, and was significantly associated with the presence of S. mutans and S. sobrinus. The severity of ECC was significantly correlated with increased DNA levels of the two bacteria. Children who were positive for S. mutans and S. sobrinus (Sm+/Sb+) were 8 times or 44 times more likely to experience ECC than children who were Sm-/Sb + or were Sm-/Sb-. CONCLUSIONS: The study evidence further suggest that children colonized by both S. mutans and S. sobrinus are at the higher risk for ECC. CLINICAL RELEVANCE: Molecular-based qPCR can be used to detect and quantify S. mutans and S. sobrinus colonization for epidemiological and clinical studies for ECC risk assessment.

Mode of delivery, mutans streptococci colonization, and early childhood caries in three- to five-year-old Thai children.

OBJECTIVE: To investigate whether mode of delivery is associated with mutans streptococci (MS) colonization and early childhood caries (ECC) in preschool Thai children. METHODS: Three hundred and fifty mothers and their 3- to 5-year-old children (184 born vaginally and 166 born by Caesarean section) participated in the study. Data included a dental examination, MS colonization assessed by the Dentocult(®) SM Strip Mutans method, and a questionnaire survey of family socio-demographic information, as well as children's birth history, dietary habits, and oral health practices. RESULTS: Overall, ECC prevalence was 56% in 3-year-old and 78% in 5-year-old Thai children. Compared to children delivered by C-section, vaginally born children experienced increased ECC prevalence (73.8% versus 59.6%; P = 0.009) and were more likely to have higher MS scores (OR = 1.8, 95% CI = 1.1-2.9), adjusting for mother's gestational age, MS score, feeding practice habits; child's age and tooth brushing habits. Children's MS scores were highly correlated with their mothers' MS scores (P < 0.001). Additionally, children's age, MS colonization, and mothers' prechewing feeding habits were the most significant risk indicators for ECC in Thai children. CONCLUSION: Our findings suggest that mode of delivery is significantly correlated with MS colonization and caries outcomes in young Thai children. Future studies are needed to further understand the possible biological mechanisms linking mode of child delivery to the colonization of cariogenic microbiota and development of ECC.

Human beta-defensin-3 up-regulates cyclooxygenase-2 expression and prostaglandin E2 synthesis in human gingival fibroblasts.

BACKGROUND AND OBJECTIVE: Oral epithelial cells express three antimicrobial peptide human beta-defensins (hBDs) that have previously been demonstrated to exert proinflammatory effects on various immune cells. We wanted to examine whether hBDs could induce cyclooxygenase-2 (COX-2) expression and prostaglandin E(2) (PGE(2)) synthesis in non-immune cells, such as human gingival fibroblasts. MATERIAL AND METHODS: Cultured fibroblasts were treated with different concentrations of hBD-1, -2, -3 or interleukin-1 beta, as a positive control, for various times, in the presence or absence of NS-398, a specific COX-2 inhibitor. The levels of COX-1 and COX-2 mRNA expression were analyzed using RT-PCR and real-time PCR. Whole cell lysates were analyzed for COX-1 and COX-2 protein expression by western blotting. Cell-free culture supernatants were assayed for PGE(2) levels by ELISA. The lactate dehydrogenase assay was performed to determine the cytotoxicity of hBDs. RESULTS: Ten and 40 microg/mL of hBD-3 up-regulated COX-2 mRNA and protein expression, consistent with COX-2 up-regulation by interleukin-1 beta, whereas hBD-1 and hBD-2 did not. However, COX-1 mRNA and protein were constitutively expressed. The time-course study revealed that hBD-3 up-regulated COX-2 mRNA and protein expression at 6 and 12 h, respectively. Consistent with COX-2 up-regulation, 10 and 40 microg/mL of hBD-3 significantly increased PGE(2) levels in cell-free culture supernatants (p < 0.05), and this was inhibited by NS-398 in a dose-dependent manner. Neither of the hBD concentrations tested in this study was toxic to the cells. CONCLUSION: These findings indicate that epithelial human beta-defensin-3 functions as a proinflammatory mediator in controlling arachidonic acid metabolism in underlying fibroblasts.