Role of IL-6 and STAT3 signaling in dihydropyridine-induced gingival overgrowth fibroblasts.

OBJECTIVES: This study analyzed the role of the interleukin (IL)-6/signal transducer and activator of transcription 3 (STAT3) pathway in dihydropyridine-induced gingival overgrowth (DIGO) fibroblasts. MATERIALS AND METHODS: Tissue samples were obtained through surgical dissection from five DIGO patients and five healthy individuals. Cell cultures were conditioned with nifedipine (Nif) (0.34 µM) and stimulated with IL-1ß (10 ng/ml) to clarify whether IL-6 upregulates extracellular matrix overproduction or has an impact on the cell proliferation rate of DIGO fibroblasts. STAT3 was knocked down using short hairpin (sh)RNA to determine its role in collagen (Col) type I alpha 1 (Colα1(I)) synthesis. RESULTS: Results showed that phosphorylated (p)STAT3 nuclear translocation was activated by a simulated autocrine concentration (50 ng/ml) of IL-6, and application of an anti-IL-6 antibody significantly decreased the pSTAT3/STAT3 ratio in DIGO fibroblasts. STAT3 knockdown significantly decreased STAT3 and Colα1(I) expressions in DIGO cells. DIGO tissues presented stronger proliferating cell nuclear antigen (PCNA) expression than did healthy individuals under the effect of IL-1ß/Nif treatment. CONCLUSIONS: Gingival inflammation (e.g., IL-1ß) and taking dihydropyridine (e.g., Nif) may additively stimulate Col overproduction through the IL-6-STAT3-Colα1(I) cascade in DIGO cells. IL-6-STAT3 signaling may be considered a target for the control of DIGO.

Bond strength of orthodontic light-cured resin-modified glass ionomer cement.

The purpose of this study was to compare the bond strengths and debonded interfaces achieved with light-cured resin-modified glass ionomer cement (RMGIC) and conventional light-cured composite resin. In addition, the effects of acid etching and water contamination were examined. One hundred human premolars were randomly divided into five equal groups. The mini Dyna-lock upper premolar bracket was selected for testing. The first four groups were treated with light-cured RMGIC with or without 15 per cent phosphoric acid-etching treatment and with or without water contamination preceding bracket bonding. The control samples were treated with the conventional light-cured Transbond composite resin under acid etching and without water contamination. Subsequently, the brackets were debonded by tensile force using an Instron machine. The modified adhesive remnant index (ARI) scores were assigned to the bracket base of the debonded interfaces using a scanning electron microscope. The bond strength and modified ARI scores were determined and analysed statistically by one-way analysis of variance and chi-square test. Under all four conditions, the bond strength of the light-cure RMGIC was equal to or higher than that of the conventional composite resin. The highest bond strength was achieved when using RMGIC with acid etching but without water contamination. The modified ARI scores were 2 for Fuji Ortho LC and 3 for Transbond. No enamel detachment was found in any group. Fifteen per cent phosphoric acid etching without moistening the enamel of Fuji Ortho LC provided the more favourable bond strength. Enamel surfaces, with or without water contamination and with or without acid etching, had the same or a greater bond strength than Transbond.

Measurement of gp130 cytokines oncostatin M and IL-6 in gingival crevicular fluid of patients with chronic periodontitis.

Several proinflammatory cytokines can induce periodontal tissue destruction and are thought to be useful indicators or diagnostic markers for periodontitis. Here, we aimed to investigate whether oncostatin M (OSM) was present in gingival crevicular fluid (GCF) and to clarify the correlation of GCF OSM and interleukin-6 (IL-6) levels with the severity of periodontitis. Sixty-two sites in 14 patients were divided into 4 groups based on probing depth (PD) and bleeding on probing (BOP). GCF was collected using paper strips from clinically health sites (PD < or = 3 mm, CAL: 1-3 mm, without BOP, n = 31), mildly diseased sites (PD < or = 3 mm, CAL: 3-5 mm, with BOP, n = 11), moderately diseased sites (PD = 4-6 mm, CAL: 5-8 mm, with BOP, n = 11), and severely diseased sites (PD > 6 mm, CAL: 8-12 mm, with BOP, n = 9). IL-6 and OSM in GCF were quantified by enzyme-linked immunosorbent assay and are expressed as concentrations (pg/ml) and total amounts (pg/site). Correlations of OSM and IL-6 levels with the severity of periodontitis in all groups were determined using Spearman rank correlation (r(s)). Our results showed that OSM and IL-6 were detected in most GCF samples. The total amounts of OSM and IL-6 were significantly positive correlated with severity of diseased sites (OSM: r(s) = 0.526, p < 0.01; IL-6: r(s) = 0.729, p < 0.01). No correlations of OSM or IL-6 concentration in GCF were found with disease severity. OSM and IL-6 levels in GCF were positively correlated to each other when expressed as either concentrations or total amounts (concentrations: r = 0.485, p < 0.01; total amounts r = 0.490, p < 0.01). In conclusion, our findings suggest that IL-6 and OSM may play a role in modulating the inflammatory cascade of chronic periodontitis.