Efeito de um curcumin modificado quimicamente sobre a reabsorção óssea inflamatória e apoptose: estudos in vivo e in vitro / Effect of a novel chemically modified curcumin in inflammatory bone resorption and apoptosis: in vivo and in vitro study

Curcumin (diferuloylmethane) é um composto polifenólico com efeito antiinflamatório e capacidade de prevenir a atividade osteolítica verificados em modelos in vitro e in vivo. No entanto, uma importante limitação no uso do curcumin são suas pobres propriedades farmacológicas, incluindo absorção e biodisponibilidade. Assim, é de grande interesse a síntese de análogos do curcumin com características bioquímicas que favoreçam suas propriedades farmacológicas, mantendo as características de segurança e efetividade. O objetivo foi avaliar o efeito de composto sintético análogo ao curcumin (CMC 2.24) sobre o processo inflamatório e osteoclastogênese em modelo de doença periodontal in vivo. A doença periodontal foi induzida em ratos por meio de injeção de 30 ug de LPS de Escherichia coli, realizadas 3x/semana durante 2 semanas. Os controles, contralaterais, receberam injeções do mesmo volume do veículo de diluição do LPS (PBS). A administração de CMC (30mg/kg) e curcumin (100mg/kg) foram feitas via intragástrica (gavagem oral) diariamente, durante 15 dias. A expressão de fosfatase ácida tartarato resistente (TRAP), indicativa de diferenciação osteoclástica, foi avaliada por meio de imunohistoquímica, a proporção de células inflamatórias e conteúdo de colágeno, em cortes corados com H/E, por estereometria, a fragmentação do DNA celular indicativa de apoptose foi avaliada por método TUNEL e a reabsorção óssea por análise de microtomografia computadorizada. Nos experimentos in vitro, células derivadas da medula óssea de camundongos C57BL/6, foram estimuladas com RANKL e tratadas com curcumin e CMC em concentração de 10µM, em diferentes períodos. O número de osteoclastos foi avaliado pela visualização do anel de actina, e a expressão gênica de MMP-9, indicativa de atividade osteoclástica, foi avaliada por RT-qPCR. De acordo com os resultados, tanto CMC quanto curcumin reduziram significativamente o infiltrado inflamatório (p<0.05) e aumentaram a proporção de fibras colágenas nos tecidos gengivais (p<0.05), em comparação ao controle-veículo. CMC, mas não curcumin, diminuiu significativamente (p<0.05) a quantidade de células TRAP positivas e a perda óssea alveolar; porém apenas curcumin reduziu significativamente (p<0.05) o número de células apoptóticas (TUNELpositivas). In vitro, tanto CMC quanto curcumin inibiram a diferenciação osteoclástica induzida por RANKL (p<0.05), independentemente do momento em que CMC e/ou curcumin foram adicionados às culturas. No entanto, apenas CMC reduziu significativamente (p<0.05) a expressão de MMP-9 nestas culturas induzidas por RANKL. Estes resultados sugerem que curcumin e CMC apresentam diferenças em seus efeitos biológicos relacionados à reabsorção óssea inflamatória neste modelo experimental de doença periodontal. Concluímos que CMC, mas não curcumin, inibe significativamente a reabsorção óssea inflamatória por um mecanismo que pode envolver a modulação da atividade de osteoclastos

Curcumin (diferuloylmethane) is a polyphenolic compound with anti-inflammatory properties and the ability to prevent the osteolytic activity both in vitro and in vivo models. The clinical use of curcumin is limited by its poor pharmacological properties, including absorption and bioavailability. This justifies the interest on the synthesis of curcumin analogues with improved pharmacological properties that retain both safety and biological properties of the natural compound. The aim was to evaluate the effect of a curcumin synthetic analogue (CMC 2.24) on RANKL-induced osteoclastogenesis in vitro and on inflammatory-driven bone resorption in a periodontal disease model in vivo. Periodontal disease was induced in rats by injections of LPS from Escherichia coli (30 ug/injection) directly on the gingival tissues, performed 3x/week during 2 weeks. The opposite site (controls) received injections of the same volume of vehicle (PBS). CMC (30 mg/kg) and curcumin (100 mg/kg) were administered by oral gavage daily, during this 2 week experimental period. Tartrate resistant acid phosphatase (TRAP) expression, which is indicative of osteoclast differentiation was assessed by immunohistochemistry, bone resorption was measured by microCT and the proportion of inflammatory cells and collagen was assessed by stereometry on H/E-stained section. Apoptosis was assessed in the gingival tissues and alveolar bone by TUNEL staining. Bone marrow stromal cells from C56Bl/7 mice were stimulated with RANKL in the presence of M-CSF and treated with 10 µM of curcumin or CMC 2.24 at different time points over a 6-day period. The number of the osteoclasts identified by actin-ring formation was counted and gene expression of MMP-9, indicative of osteoclast activity, was assessed by RT-qPCR. Both curcumin and CMC significantly reduced the inflammatory infiltrate (p<0.05 vs vehicle control); however only CMC significantly increased the proportion of collagen fibers in gingival tissues (p<0.05 vs vehicle control). CMC, but not curcumin, decreased the number of TRAP positive cells (p<0.05) and the alveolar bone loss (p<0.05); however only curcumin reduced the number of TUNEL positive cells (p<0.05). In vitro, both CMC and curcumin decreased the number of osteoclasts (p<0.05); but only CMC reduced MMP-9 gene expression (p <0.05). The data suggests that although curcumin and CMC have different biological mechanisms of action, both presented promising therapeutic properties in the treatment of inflammatory diseases, due to inhibition of inflammatory responses and improved healing process. However, only CMC was effective in reducing inflammatorydriven bone resorption in this experimental model

Instrumentation of dental implants: a literature review

Introduction and Objective: The aim of this study was to review the literature on the systems used to decontaminate the implant's surface. Different instruments have been proposed, but there is no agreement in the literature about which methods would be more efficient with no damage to the implant surface. It was reported the use of plastic, carbon fiber, stainless-steel and titanium curettes and also the use of other systems such as ultrasonic points with different tips, rubber cups and air abrasion. Literature review: In most of the studies, the injury caused on the titanium surface at the time of instrumentation was examined. In others, the cell adhesion on the titanium dental implants following instrumentation of the implant surface was observed. Moreover, to enhance cleaning around implants, ultrasonic systems were recently tested. Conclusion: Metal instruments can lead to major damage to implant surface, therefore, they are not indicated for decontamination of dental implants surfaces. Furthermore, non-metallic instruments, such as plastic curettes, rubber cups, air abrasion and some ultrasonic systems seem to be better choices to remove calculus and plaque of the sub- and supra-gingival peri-implant area. It is noteworthy that more studies evaluating the effects of these systems are required to establish best practices to be used in the treatment of patients with dental implants.