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Abstract: Hydroxymethylglutaryl-coenzyme A reductase inhibitors (statins) are widely used cholesterol-lowering agents that also possess anti-inflammatory activities. Cysteine-rich 61 (Cyr61) and CCL2 are potential osteolytic mediators in inflammatory bone diseases. The study assessed the effect of simvastatin on tumor necrosis factor α (TNF- α)--induced synthesis of Cyr61 and CCL2 in MG-63 human osteoblastic cells. The therapeutic effect of simvastatin on rat apical periodontitis was also examined. The synthesis of Cyr61 in MG-63 was assessed by Western analysis. Expression of CCL2 was examined by an enzyme-linked immunosorbent assay. The effect of simvastatin on induced rat periapical lesion was examined radiographically and immunohistochemically. Western blot showed that TNF-α stimulated Cyr61 synthesis in MG-63, whereas simvastatin attenuated this effect in a dose-dependent manner. Simvastatin also reduced the levels of TNF-α–induced CCL2, and exogenous Cyr61 restored the inhibitory effects. Radiography and histopathology revealed that the administration of simvastatin markedly diminished the severity of induced rat periapical lesions. The numbers of Cyr61-synthesizing osteoblasts and CD-68–positive macrophages were also decreased. Simvastatin suppresses the progression of apical periodontitis, possibly by diminishing Cyr61 expression in osteoblasts and, subsequently, macrophage chemotaxis into the lesions. [Copyright &y& Elsevier]

Abstract: Recent investigations indicate that epigallocatechin-3-gallate (EGCG), the major polyphenol of green tea, has anti-inflammatory properties. This study assessed the effect of EGCG on oncostatin M (OSM)–induced synthesis of cysteine-rich 61 (Cyr61), a potential osteolytic mediator, in MG-63 human osteoblastic cells. The therapeutic effect of EGCG in apical periodontitis in rats was also examined. Western blot analysis showed that OSM stimulated Cyr61 synthesis in MG-63 in a time-dependent manner, whereas EGCG readily attenuated this effect. On the other hand, Cyr61 treatment of MG-63 cells induced the release of CCL2, a chemokine responsible for macrophage chemotaxis. In a rat model of induced apical periodontitis, radiography and histopathology revealed that administration of EGCG markedly diminished the severity of periapical lesions. The numbers of Cyr61-synthesizing osteoblasts and infiltrating macrophages were also decreased. Thus, EGCG suppresses the progression of apical periodontitis, possibly by diminishing Cyr61 expression in osteoblasts and, subsequently, macrophage chemotaxis into the lesions. [Copyright &y& Elsevier]

In this work, the influence of thermal oxidation treatments of Ti6Al4V at 500°C and 700°C for 1 h on the in vitro corrosion behaviour and osteoblast response is studied. The potential of these treatments, aimed to improve the wear surface performance as biomaterial, relies in the formation of an outer “ceramic” layer of rutile. The corrosion behaviour was evaluated in simulated human fluids by electrochemical impedance spectroscopy and anodic polarisation tests. The effect of these thermal oxidation treatments on osteoblastic behaviour was studied in primary cultures of human osteoblastic cells. Results show that thermal oxidation treatments do not decrease the high in vitro corrosion resistance of the Ti6Al4V alloy. Osteoblast adhesion studies indicate that thermal oxidation treatments do not impair the material biocompatibility. Moreover, the thermal oxidation at 700°C enhances the in vitro osteoblastic cell attachment compared to the thermal oxidation at 500°C. [Copyright &y& Elsevier]

The effect of two biomaterials, polyethylene and α-alumina, on interleukin-6 (IL-6) secretion and expression has been studied in human osteoblasts in primary culture. Human osteoblastic cells were derived from fresh trabecular bone explants removed during total knee arthroplasty. On reaching confluence, cells were subcultured in 6 well plates; the resulting subcultures were incubated until confluence and polyethylene or α-alumina particles were added to some while the rest were left as controls. The IL-6 mRNA levels were assessed by reverse transcription (RT) followed by polymerase chain reaction (PCR). IL-6 secretion was measured in the conditioned medium. The IL-6 expression was higher in the presence of both biomaterials. Maximum expression occurred in response to a dose of 50 mg particles/well with both biomaterials and was greater after polyethylene particle addition than after α-alumina particle addition at this dose. The maximum IL-6 secretion elicited by α-alumina was produced at 10 mg particles/well while maximum response with polyethylene required 50 mg/well. At a dose of 10 mg/well, α-alumina particles induced more secretion than 10 mg of polyethylene particles. Nevertheless, at a dose of 50 mg/well maximum secretion was produced with polyethylene particles. In conclusion and in our experimental conditions, polyethylene as well as α-alumina increased both the expression and the secretion of IL-6 in human osteoblastic cells in primary culture and stimulation from polyethylene appears stronger than that from α-alumina at the same dose. [Copyright &y& Elsevier]