Periodontal Commensals and Pathogens Differentially Modulate Immuno-Inflammatory Response in Human Oral Keratinocytes.

OBJECTIVE: To investigate the immunoinflammatory response in the crosstalk of human oral keratinocytes (HOKs) with selected periodontal commensals and pathogens. METHODS: Four representative viable oral bacteria, including periodontal commensals (Streptococcus mutans, Sm; and Actinomyces israelii, Ai) and pathogens (Aggregatibacter actinomycetemcomitans, Aa; and Porphyromonas gingivalis, Pg), were selected. A viable bacteria-HOKs interactive model was tested under various conditions of oxygen, antibiotics, duration and multiplicity of infection (MOI). The expression of IL-6 and IL-8 in HOKs was assessed by real-time qPCR and ELISA. RESULTS: An MOI of 1 was determined to be the appropriate ratio of bacteria and HOKs with substantial amounts of viable bacterial cells and HOKs in an antibiotic-free medium under aerobic conditions for 2 h. Sm and Pg significantly upregulated the expression of IL-6 and IL-8 (P < 0.05), while Ai and Aa could not induce significant levels of these cytokines with reference to the control. CONCLUSION: Within the limitations of this study, the current findings suggest that periodontal commensals and pathogens may differentially modulate immunoinflammatory response in human oral keratinocytes.

[Mechanism of advanced glycation end-products in the inducement of apoptosis of human gingival fibroblast and related effect of puerarin in the process].

OBJECTIVE: To observe the effect of synthesized advanced glycation end-products (AGE) on reactive oxygen species formation and apoptosis of the cultured human gingival fibroblast and investigate the potential mechanisms of AGE in the modification of periodontal impairment. METHODS: AGE products with different concentrations [0, 50, 150 mg/L AGE-human serum albumin (AGE-HSA)] were incubated with human gingival fibroblast for 48 h, respestively. Flow cytometry was used to detect intracellular reactive oxygen species and cell apoptosis. The culture media with 50 mg/L AGE-HSA was exposed to 0.24 mmol/L puerarin for 48 h and then cell apoptosis was measured. RESULTS: The values of cellular apoptotic rate in 0, 50, 150 mg/L AGE-HSA groups were (1.60 ± 0.30)%, (29.43 ± 1.45)%, (49.20 ± 4.43)%, respectively. The differences between each AGE-HSA group and control were statistically significant (P < 0.05). AGE-HSA increased cell apoptosis in a dose-dependent manner (150 mg/L > 50 mg/L > 0 mg/L, P < 0.05). The cellular fluorescence intensity value was elevated as the concentration of AGE-HSA increased (P < 0.05). After incubation of human gingival fibroblast with AGE-HSA for 48 h, there was a significant decrease in apoptotic rate in puerarin group [(6.37 ± 3.02)%], compared with the control [(29.43 ± 1.45)%, P < 0.05]. CONCLUSIONS: AGE can stimulate apoptosis of human gingival fibroblast, which may be mediated by oxidative stress. Puerarin may protect periodontal tissues by inhibiting the apoptosis.