Efeitos da radioterapia no processo de neoformação óssea na interface osso/implante e na expressão de citocinas IL-6 e TGF-ß: estudo in vivo
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Data
2018-05-02
Autores
Costa, Bruno César Almeida
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Universidade Estadual Paulista (Unesp)
Resumo
No tecido ósseo, as injúrias decorrentes da radioterapia variam desde osteopenia até osteoradionecrose e devido a estas alterações, pacientes irradiados portadores de implantes vêm demonstrando maior taxa de insucesso. O objetivo neste estudo foi avaliar os efeitos da radioterapia, simulando uma dose total de um tratamento radioterápico convencional para pacientes oncológicos, na neoformação óssea ao redor de implantes instalados em fêmures de ratos, assim como na expressão de citocinas IL-6 e TGF-ß. Foram utilizados neste estudo 36 ratos que receberam implantes rosqueados de titânio grau V nos fêmures esquerdos. Os animais foram divididos em 3 grupos: a) Grupo controle (C): cirurgia de colocação dos implantes (tecido sadio sem irradiação); b) Grupo irradiação (I): irradiação e após 4 semanas cirurgia de colocação dos implantes c) Grupo irradiação imediata (IP): cirurgia de colocação dos implantes e depois de 24 horas irradiação. A irradiação foi realizada em duas etapas com doses de 15 Gy, totalizando ao final da segunda dose 30 Gy. Os animais foram eutanasiados nos períodos de 3 dias, 2 e 7 semanas após o tratamento. No momento da eutanásia, 0,5 ml de sangue foi coletado e os níveis séricos de IL-6 e TGF-β foram mensurados pelo método imunoenzimático (ELISA). Em cada período 04 animais foram submetidos à microtomografia computadorizada (µCT), visando avaliar a neoformação óssea na interface osso-implante. Os valores obtidos foram submetidos ao teste ANOVA um fator para análise estatística e quando necessário foi aplicado o teste de comparação múltipla de Tukey (p<0,05). Nos resultados obtidos por meio da análise de microtomografia em geral não foi observada diferença estatística entre os grupos (p>0,05). Contudo, no parâmetro volume ósseo observou-se no período de 2 semanas, diferença estatística (p<0,05) entre os grupos C e IP e o parâmetro separação de trabéculas mostrou no período de 2 e 7 semanas, diferença estatística (p<0,05) entre os grupos C e IP e Na avaliação de IL-6 o grupo C exibiu o maior valor e foi observada diferença estatisticamente significante (p<0,05) entre ele e os demais grupos em todos os períodos. Na avaliação de TGF-β foi observada diferença estatisticamente significante (p<0,05) entre o grupo I em comparação com os outros grupos nos períodos de 3 dias e 2 semanas, sendo o grupo I aquele que apresentou maior expressão. Concluiu-se que o osso irradiado recupera-se da irradiação com o decorrer do tempo, porém quando a irradiação ocorre imediata a cirurgia do implante o tecido ósseo exibe alterações mais significativas.
In bone tissue, the injuries resulting from radiotherapy vary from osteopenia to osteoradionecrosis and due to these alterations, irradiated patients with implants have been showing a higher rate of failure. The objective of this study was to evaluate the effects of radiotherapy, simulating a total dose of a conventional radiotherapy treatment for cancer patients, in the new bone formation around implants in rat femurs, as well as in the expression of IL-6 and TGF-β cytokines . Thirty-six rats receiving grade V titanium implants in the left femora were used in this study. The animals were divided into 3 groups: a) Control group (C): implant placement surgery (healthy tissue without irradiation); b) Group irradiation (I): irradiation and after 4 weeks implant placement surgery c) Immediate irradiation (IP) group: implant placement surgery and after 24 hours irradiation. Irradiation was performed in two steps with doses of 15 Gy, totaling at the end of the second dose 30 Gy. The animals were euthanized at 3 days, 2 and 7 weeks after treatment. At the time of euthanasia, 0.5 ml of blood was collected and serum levels of IL-6 and TGF-β were measured by the enzyme-linked immunosorbent assay (ELISA). In each period, 04 animals were submitted to computerized microtomography (μCT), aiming to evaluate the bone neoformation at the bone-implant interface. The obtained values were submitted to ANOVA a factor for statistical analysis and when necessary the Tukey multiple comparison test (p <0.05) was applied. In the results obtained through the microtomography analysis in general no statistical difference was observed between the groups (p> 0.05). However, the parameter separation of trabeculae showed, in the period of 2 and 7 weeks, statistical difference (p <0.05) between groups C and PI and in the bone volume parameter showed in the period of 2 weeks, statistical difference (p <0, 05) between groups C and IP. In the evaluation of IL-6, group C showed the highest value and a statistically significant difference (p <0.05) was observed between him and the other groups in all periods. In the evaluation of TGF-β, a statistically significant difference (p <0.05) was observed between group I in comparison with the other groups in the periods of 3 days and 2 weeks, with group I being the one with the highest expression. It was concluded that irradiated bone recovers from irradiation over time, but when irradiation occurs near implant surgery, the bone tissue exhibits more significant changes.
In bone tissue, the injuries resulting from radiotherapy vary from osteopenia to osteoradionecrosis and due to these alterations, irradiated patients with implants have been showing a higher rate of failure. The objective of this study was to evaluate the effects of radiotherapy, simulating a total dose of a conventional radiotherapy treatment for cancer patients, in the new bone formation around implants in rat femurs, as well as in the expression of IL-6 and TGF-β cytokines . Thirty-six rats receiving grade V titanium implants in the left femora were used in this study. The animals were divided into 3 groups: a) Control group (C): implant placement surgery (healthy tissue without irradiation); b) Group irradiation (I): irradiation and after 4 weeks implant placement surgery c) Immediate irradiation (IP) group: implant placement surgery and after 24 hours irradiation. Irradiation was performed in two steps with doses of 15 Gy, totaling at the end of the second dose 30 Gy. The animals were euthanized at 3 days, 2 and 7 weeks after treatment. At the time of euthanasia, 0.5 ml of blood was collected and serum levels of IL-6 and TGF-β were measured by the enzyme-linked immunosorbent assay (ELISA). In each period, 04 animals were submitted to computerized microtomography (μCT), aiming to evaluate the bone neoformation at the bone-implant interface. The obtained values were submitted to ANOVA a factor for statistical analysis and when necessary the Tukey multiple comparison test (p <0.05) was applied. In the results obtained through the microtomography analysis in general no statistical difference was observed between the groups (p> 0.05). However, the parameter separation of trabeculae showed, in the period of 2 and 7 weeks, statistical difference (p <0.05) between groups C and PI and in the bone volume parameter showed in the period of 2 weeks, statistical difference (p <0, 05) between groups C and IP. In the evaluation of IL-6, group C showed the highest value and a statistically significant difference (p <0.05) was observed between him and the other groups in all periods. In the evaluation of TGF-β, a statistically significant difference (p <0.05) was observed between group I in comparison with the other groups in the periods of 3 days and 2 weeks, with group I being the one with the highest expression. It was concluded that irradiated bone recovers from irradiation over time, but when irradiation occurs near implant surgery, the bone tissue exhibits more significant changes.
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Palavras-chave
Osseointegração, Implantes, Radioterapia, Citocinas, Neoformação, Osseointegration, Implants of titanium, Radiotherapy, Cytokines