Efeito do Fumarato de Dimetila (DMF), um ativador de Nrf2, sobre a destruição de tecido mineralizado e não mineralizado em modelo experimental de periodontite em ratos
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Data
2022-03-21
Autores
Costa, Vitória Bonan
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Universidade Estadual Paulista (Unesp)
Resumo
O estresse oxidativo, definido como o desequilíbrio entre a produção de espécies reativas de oxigênio (ROS) e os mecanismos antioxidantes, tem sido correlacionado a patogênese de uma série de doenças inflamatórias, incluindo a doença periodontal. A produção exagerada de ROS pode aumentar o dano oxidativo de proteínas no periodonto e contribuir para destruição tecidual. A produção de enzimas antioxidantes, necessária para contrabalancear os efeitos nocivos do estresse oxidativo, é em parte regulada pela via de sinalização Nrf2 (nuclear factorerythroid 2 related factor 2). Além de atuar na ativação de fatores antioxidantes, Nrf2 é capaz de inibir ativação de citocinas e quimiocinas inflamatórias, metaloproteinases da matriz e fatores de transcrição envolvidos na modulação de citocinas pró-inflamatórias, todos fatores envolvidos na patogênese de doenças inflamatórias. Em função de suas atividades biológicas e ausência de toxicidade, um ativador farmacológico de Nrf2, fumarato de dimetila (DMF), tem sido utilizado no tratamento clínico de doenças inflamatórias, como esclerose múltipla e psoríase, e diversos estudos clínicos têm avaliado seu potencial terapêutico em outras patologias inflamatórias como câncer, diabetes e artrite reumatoide. Além da função antioxidante, DMF têm demonstrado reduzir a ativação de vias de sinalização intracelular importantes na produção de mediadores inflamatórios, como NF-kB, além de inibir a osteoclastogênese in vitro e a reabsorção óssea in vivo. Na doença periodontal, poucos estudos têm avaliado o papel de Nrf2 sobre a progressão da doença, e até o momento, não há dados sobre os efeitos biológicos da administração de DMF na periodontite. A hipótese deste trabalho é que a administração de DMF pode reduzir a severidade da destruição do tecido conjuntivo e a reabsorção do osso alveolar associadas à periodontite, através da modulação de vias de sinalização intracelular necessárias para expressão e ativação de citocinas inflamatórias e homeostase redox. Para avaliar esta hipótese, a periodontite foi induzida pela colocação de ligaduras ao redor dos primeiros molares inferiores, bilateralmente, e DMF (100mg/kg) foi administrado por gavagem oral, diariamente, durante 10 dias. Água destilada foi administrada aos animais controle (com e sem ligadura). RT-qPCR foi usado para determinar a expressão de fator de necrose tumoral alfa (Tnf-α), prostaglandina endoperoxido-sintase-2 (Ptgs-2), óxido nítrico sintase induzível (iNOS), e superóxido dismutase (Sod1) nos tecidos gengivais. O processo inflamatório foi avaliado através da análise estereométrica, enquanto a modulação da sinalização Fator Nuclear κB (NF-kB) foi avaliada por western-blot (IKBα). A reabsorção óssea foi determinada por microtomografia computadorizada. Os resultados indicaram que DMF reduziu marcadamente a inflamação nos tecidos gengivais prevenindo o aumento do infiltrado celular e de vasos sanguíneos. Estes efeitos foram associados à redução dos níveis de mRNA de Tnf-alpha e iNOS e aumento da expressão antioxidante de Sod. A reabsorção óssea e os níveis de IKBα não foram modulados pelo composto. Estes resultados indicam que a administração oral de DMF inibiu a resposta inflamatória associada à periodontite, e pode ser útil no tratamento desta condição.
Oxidative stress, defined as the imbalance between the production of reactive oxygen species (ROS) and antioxidant mechanisms, has been correlated with the pathogenesis of a number of inflammatory diseases, including periodontal disease. The exaggerated production of ROS can increase the oxidative damage of proteins in the periodontium and contribute to tissue destruction. The production of antioxidant enzymes, necessary to counterbalance the harmful effects of oxidative stress, is in part regulated by the Nrf2 (nuclear factor-erythroid 2 related factor 2) signaling pathway. In addition to acting on the activation of antioxidant factors, Nrf2 is capable of inhibiting the activation of inflammatory cytokines and chemokines, matrix metalloproteinases and transcription factors involved in the modulation of pro-inflammatory cytokines, all factors involved in the pathogenesis of inflammatory diseases. Due to its biological activities and lack of toxicity, a pharmacological activator of Nrf2, dimethyl fumarate (DMF), has been used in the clinical treatment of inflammatory diseases, such as multiple sclerosis and psoriasis, and several clinical studies have evaluated its therapeutic potential in other inflammatory pathologies such as cancer, diabetes and rheumatoid arthritis. In addition to its antioxidant function, DMF has been shown to reduce the activation of intracellular signaling pathways important in the production of inflammatory mediators, such as NF-kB, in addition to inhibiting osteoclastogenesis in vitro and bone resorption in vivo. In periodontal disease, few studies have evaluated the role of Nrf2 on disease progression, and to date, there are no data on the biological effects of DMF administration in periodontitis. The hypothesis of this work is that the administration of DMF can reduce the severity of connective tissue destruction and alveolar bone resorption associated with periodontitis, through the modulation of intracellular signaling pathways necessary for the expression and activation of inflammatory cytokines and redox homeostasis. To assess this hypothesis, periodontitis was induced by placing ligatures around the first molars, and DMF (100mg/kg) was administered by oral gavage daily for 10 days. Distilled water was administered to control animals (with and without ligature). RT-qPCR was used to determine the expression of Tnf-alpha, prostaglandin-endoperoxide synthase-2 (Ptgs-2), iNOS and superoxide dismutase (Sod1) in gingival tissues. The inflammatory process was evaluated by stereometric analysis, while the modulation of NF-kB (IKBα) signaling was evaluated by western-blot. Bone resorption was determined by computed microtomography. The results indicated that DMF did not prevent bone resorption, but markedly reduced inflammation in gingival tissues by preventing increased cell and blood vessel infiltration, and decreasing Tnf-alpha and iNOS mRNA levels. The pharmacological agent also increased the antioxidant expression of Sod in periodontal tissues. Interestingly, IKBα levels were not modulated by DMF. These results indicate that oral administration of DMF inhibited the inflammatory response associated with periodontitis, and may be useful in the treatment of this condition.
Oxidative stress, defined as the imbalance between the production of reactive oxygen species (ROS) and antioxidant mechanisms, has been correlated with the pathogenesis of a number of inflammatory diseases, including periodontal disease. The exaggerated production of ROS can increase the oxidative damage of proteins in the periodontium and contribute to tissue destruction. The production of antioxidant enzymes, necessary to counterbalance the harmful effects of oxidative stress, is in part regulated by the Nrf2 (nuclear factor-erythroid 2 related factor 2) signaling pathway. In addition to acting on the activation of antioxidant factors, Nrf2 is capable of inhibiting the activation of inflammatory cytokines and chemokines, matrix metalloproteinases and transcription factors involved in the modulation of pro-inflammatory cytokines, all factors involved in the pathogenesis of inflammatory diseases. Due to its biological activities and lack of toxicity, a pharmacological activator of Nrf2, dimethyl fumarate (DMF), has been used in the clinical treatment of inflammatory diseases, such as multiple sclerosis and psoriasis, and several clinical studies have evaluated its therapeutic potential in other inflammatory pathologies such as cancer, diabetes and rheumatoid arthritis. In addition to its antioxidant function, DMF has been shown to reduce the activation of intracellular signaling pathways important in the production of inflammatory mediators, such as NF-kB, in addition to inhibiting osteoclastogenesis in vitro and bone resorption in vivo. In periodontal disease, few studies have evaluated the role of Nrf2 on disease progression, and to date, there are no data on the biological effects of DMF administration in periodontitis. The hypothesis of this work is that the administration of DMF can reduce the severity of connective tissue destruction and alveolar bone resorption associated with periodontitis, through the modulation of intracellular signaling pathways necessary for the expression and activation of inflammatory cytokines and redox homeostasis. To assess this hypothesis, periodontitis was induced by placing ligatures around the first molars, and DMF (100mg/kg) was administered by oral gavage daily for 10 days. Distilled water was administered to control animals (with and without ligature). RT-qPCR was used to determine the expression of Tnf-alpha, prostaglandin-endoperoxide synthase-2 (Ptgs-2), iNOS and superoxide dismutase (Sod1) in gingival tissues. The inflammatory process was evaluated by stereometric analysis, while the modulation of NF-kB (IKBα) signaling was evaluated by western-blot. Bone resorption was determined by computed microtomography. The results indicated that DMF did not prevent bone resorption, but markedly reduced inflammation in gingival tissues by preventing increased cell and blood vessel infiltration, and decreasing Tnf-alpha and iNOS mRNA levels. The pharmacological agent also increased the antioxidant expression of Sod in periodontal tissues. Interestingly, IKBα levels were not modulated by DMF. These results indicate that oral administration of DMF inhibited the inflammatory response associated with periodontitis, and may be useful in the treatment of this condition.
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Palavras-chave
Periodontite, Fumarato de dimetilo, Inflamação, Ratos