IL-6 and soluble IL-6 receptor stimulate the production of MMPs and their inhibitors via JAK-STAT and ERK-MAPK signalling in human chondrocytes.

Elevated concentrations of IL-6 (interleukin-6) and sIL-6r (soluble IL-6 receptor) in the synovial fluid and serum of patients with arthritis have been implicated in joint cartilage destruction. This study examined the effects of IL-6 and sIL-6r on the expression of MMPs (matrix metalloproteinases), TIMPs (tissue inhibitor of metalloproteinases), the plasminogen activation system including tPA (tissue-type PA), uPA (urokinase-type PA) and PAI-1 (PA inhibitor type 1) using chondrocytes derived from normal human femur cartilage. The cells were cultured with or without 50 ng/ml IL-6 and/or 30 ng/ml sIL-6r in the presence or absence of the JAK3 (Janus kinase 3) inhibitor WHI-P131 or the MEK [MAPK (mitogen-activated protein kinase)/ERK (extracellular signal protein kinase) kinase] inhibitor PD98059 for up to 28 days. The expression of MMPs, TIMPs, uPA, tPA and PAI-1 was investigated at the mRNA and protein levels. MMP protein expression and pSTAT3 (phosphorylation of signal transducer and activator of transcription 3) and pERK (phosphorylation of ERK) were also measured. Treatment with both IL-6 and sIL-6r markedly increased the expression of MMP-1, MMP-13, TIMP-1 and PAI-1, while significantly decreasing the expression of tPA and uPA and stimulating pSTAT3 and pERK. Adding WHI-P131 or PD98059 decreased IL-6 and sIL-6r enhancement of MMP-1, -3 and -13. The results suggest that IL-6 and sIL-6r stimulate the production of MMPs and their inhibitor via JAK-STAT and ERK-MAPK signalling in chondrocytes.

Associations among distributions of dental postgraduate residents, dentists and clinical training facilities in Japan.

The purpose of this study was to evaluate the correlation and distribution of dental postgraduate residents, dentists and clinical training facilities in each prefecture to analyze the regional distribution and supply of dentists in Japan. The results were also compared with referential data for medicine. The coefficient of correlation between the dentist index and dental postgraduate resident index was r = 0.76 (P < 0.001) in 2006. The distribution (coefficient of variation) was greatest for the dental postgraduate resident index. The numbers of dentists per 100,000 population in prefectures with dental colleges were significantly higher in 1986, 1996 and 2006 for each comparison (P < 0.001). Coefficients of correlation between dentist index and dental postgraduate resident index were r = 0.65 (P < 0.01) in prefectures with dental colleges and r = 0.11 in those without dental colleges in 2006. The prefectures with high level of numbers of cooperative-type clinical training facilities had dental colleges.

Receptor activator of NF-kappaB ligand induces the expression of carbonic anhydrase II, cathepsin K, and matrix metalloproteinase-9 in osteoclast precursor RAW264.7 cells.

Interleukin-1 (IL-1) is a proinflammatory cytokine that is a potent stimulator of bone resorption and an inhibitor of bone formation, whereas macrophage colony-stimulating factor (M-CSF) and receptor activator of NF-kappaB (RANK) ligand (RANKL) are essential and sufficient for osteoclast differentiation. Recently, we showed that IL-1alpha affects mineralized nodule formation in vitro and halts bone matrix turnover. We also showed that IL-1alpha stimulates osteoclast formation via the interaction of RANKL with RANK by increasing M-CSF and prostaglandin E(2) and decreasing osteoprotegerin. Here, we examined the effects of IL-1alpha or RANKL and/or M-CSF in the presence of IL-1alpha on the expression of carbonic anhydrase II (CAII), cathepsin K, matrix metalloproteinase-9 (MMP-9), RANK, M-CSF receptor (c-fms), and c-fos transcription factor using RAW264.7 cells as osteoclast precursors. Cells were cultured for up to 14 days in 0 or 100 U/ml IL-1alpha and either 50 ng/ml RANKL, 10 ng/ml M-CSF, or 50 ng/ml RANKL+10 ng/ml M-CSF in the presence of 100 U/ml IL-1alpha. The formation of osteoclast-like cells was estimated using tartrate-resistant acid phosphatase staining. Expression of the genes coding for the six proteins of interest was determined using real-time PCR, and the expression of the three enzymes was examined using Western blotting or ELISA. In the presence of IL-1alpha, expression of CAII, cathepsin K, and MMP-9 was markedly increased in cells cultured with RANKL or M-CSF+RANKL, whereas expression was difficult to detect in cells cultured with IL-1alpha alone and M-CSF. RANK and c-fos expression was also increased in cells cultured with RANKL or M-CSF+RANKL in the presence of IL-1alpha, whereas c-fms expression did not change. These results indicate that the expression of CAII, cathepsin K, and MMP-9 in RAW264.7 cells is not induced by M-CSF, but by RANKL in the presence of IL-1alpha.

The effect of IL-1beta on the expression of inflammatory cytokines and their receptors in human chondrocytes.

Cytokines released at sites of inflammation and infection can alter the normal processes of cartilage turnover, resulting in pathologic destruction or formation. Interleukin (IL)-1beta plays a central role in the pathophysiology of cartilage damage and degradation in arthritis. In the present study, we examined the effect of IL-1beta on the expression of IL-1beta, IL-6, IL-8, IL-11, tumor necrosis factor-alpha (TNF-alpha), and their receptors in human chondrocytes. The cells were cultured either with or without 100 U/ml of IL-1beta for up to 28 days. The level of expression of the cytokines and their receptors was estimated by determining mRNA levels using real-time PCR or by determining protein levels using ELISA. The expression of IL-1beta, IL-8, and TNF-alpha markedly increased in the presence of IL-1beta after day 14 of culture. The expression of IL-6 and IL-11 increased greatly in the presence of IL-1beta on day 1 and after day 14 of culture. The expression of IL-1beta, IL-8, IL-11, and TNF-alpha receptors significantly decreased in the presence of IL-1beta after day 14 of culture, whereas the expression of IL-6 receptor significantly increased. The expression of these cytokines, except for IL-6, decreased with the addition of human IL-1 receptor antagonist. These results suggest that IL-1beta promotes the resolution system of cartilage matrix turnover through an increase in inflammatory cytokine production by chondrocytes and that it also may promote the autocrine action of IL-6 through an increase in IL-6 receptor expression in the cells.

Fibronectin immobilization using water-soluble carbodiimide on poly-L-lactic acid for enhancing initial fibroblast attachment.

The aim of this study is to evaluate the influence of fibronectin immobilization on poly-L-lactic acid (PLA) films on the initial attachment of human gingival fibroblasts. Carboxylic acid groups are chemically introduced on the PLA films' surface by surface hydrolysis with 0.5 M NaOH. The contact angle of PLA surface with respect to double-distilled water decreases significantly after NaOH hydrolysis. X-ray photoelectron spectroscopy (XPS) also reveals significantly higher intensities of C(C=O)/C(C-O) after NaOH hydrolysis. Fibronectin is immobilized onto the hydrolyzed PLA surface through a condensation reaction between the carboxylic acid groups on the hydrolyzed PLA surface and the amino groups of fibronectin using water-soluble carbodiimide. XPS analysis shows that the fibronectin-immobilized PLA surface is enriched with nitrogen atoms. The immobilization of fibronectin significantly enhances the number of initially attached human gingival fibroblasts on the PLA surface. No obvious differences in morphology are noted between fibroblasts cultured on native PLA and on fibronectin-immobilized PLA. Fibronectin can be immobilized onto the PLA surface after NaOH hydrolysis and this is effective in enhancing the initial attachment of human gingival fibroblasts.

Improvement of periodontal status by green tea catechin using a local delivery system: a clinical pilot study.

The purpose of this study was to determine the usefulness of green tea catechin for the improvement of periodontal disease. The minimum inhibitory concentration (MIC) and bactericidal activity of green tea catechin against black-pigmented, Gram-negative anaerobic rods (BPR) were measured. Hydroxypropylcellulose strips containing green tea catechin as a slow release local delivery system were applied in pockets in patients once a week for 8 weeks. The clinical, enzymatic and microbiological effects of the catechin were determined. Green tea catechin showed a bactericidal effect against Porphyromonas gingivalis and Prevotella spp. in vitro with an MIC of 1.0 mg/ml. In the in vivo experiment, the pocket depth (PD) and the proportion of BPR were markedly decreased in the catechin group with mechanical treatment at week 8 compared with the baseline with significant difference. In contrast, PD and BPR were similar to the baseline and the value at the end of the experimental period in the placebo sites of scaled groups. The peptidase activities in the gingival fluid were maintained at lower levels during the experimental period in the test sites, while it reached 70% of that at baseline in the placebo sites. No morbidity was observed in the placebo and catechin groups without mechanical treatment. Green tea catechin showed a bactericidal effect against BPR and the combined use of mechanical treatment and the application of green tea catechin using a slow release local delivery system was effective in improving periodontal status.