Efeito do estrógeno (E2) e da Triiodotironina (T3) na síntese proteica de RANKL e TNF-α em células osteoblásticas derivadas do tecido adiposo
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2017-02-16
Autores
Costa, Sarah Maria Barneze [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A regulação da remodelação óssea ocorre por meio de fatores locais e sistêmicos. Entre os fatores locais estão as citocinas: Receptor Activator of Nuclear Factor Kappa B Ligand (RANKL), presente nos osteoblastos, e Receptor Activator of Nuclear Factor Kappa B (RANK), presente nos osteoclastos, além de outras citocinas como o Tumor Necrosis Factor Alpha (TNF-α) que podem agir no processo de deposição e/ou reabsorção óssea in vivo. Entre os fatores sistêmicos que participam da remodelação óssea estão os hormônios estrógeno (E2) e triiodotironina (T3). O objetivo do trabalho foi verificar a ação do E2, infrafisiológico (simulando a menopausa) e T3, suprafisiológico (simulando hipertireoidismo) em osteoblastos humanos derivados de células troncos mesenquimais (CTMs) na síntese proteica de RANKL e TNF-α. Os osteoblastos foram incubados por 72 horas na presença de E2 em dose fisiológica (E2F/10-8M) e infrafisiológica (E2I/10-9M), e T3 em dose fisiológica (T3F/10-9M) e suprafisiológica (T3S/10-8M), e quantificada a matriz mineralizada óssea e a síntese proteica de RANKL e TNF-α por Western Blot. A análise estatística dos dados foi realizada pelo teste de variância ANOVA complementada pelo teste de Tukey, sendo o nível de significância considerado p<0,05. O tratamento de E2 em dose E2F (1,96± 0,48; p<0,05) e E2I (3,18±0,31; p<0,001) elevou a síntese proteica de RANKL comparado ao controle (C) (1,00±0,32), e de TNF-α em dose de E2F (3,61±0,45; p<0,05) e E2I (2,45±0,07; p<0,05) também aumentou em relação ao C (1,13±0,19). Assim como o E2, o T3 elevou os níveis proteicos de RANKL em T3F (1,18±0,10; p<0,05) e T3S (1,14±0,004; p<0,05) comparado ao controle (1,00±0,02), porém, TNF-α diminui em dose de T3S (0,82±0,09; p<0,05) relacionado ao T3F (1,00±0,09) e C (0,99±0,04). Com isso, E2I diminuiu a matriz mineralizada óssea e aumentou a síntese de ambas as proteínas estudadas, o que nos leva a especulação de que a reabsorção óssea observada na menopausa seja via RANKL e TNF-α. Por outro lado, na mimetização de hipertireoidismo com o T3S, observamos diminuição da matriz mineralizada óssea, supressão da síntese proteica de TNF-α e aumento de RANKL, o que nos leva a inferir que o mecanismo de reabsorção óssea no hipertireoidismo seja via RANKL.
The regulation of bone remodeling is intermediated by local and systemic factors. The cytokines are among the local factors: Receptor Activator of Nuclear Factor Kappa B Ligand (RANKL), present in osteoblasts, and Receptor Activator of Nuclear Factor Kappa B (RANK), present in osteoclasts, in addition to other cytokines such as Tumor Necrosis Factor Alpha (TNF-α) that can act in the process of bone deposition and/or resorption in vivo. Hormones are among the systemic factors involved in bone remodeling, estrogen (E2) and triiodothyronine (T3). The aim of the study was to verify the action of E2, infraphysiological (simulating menopause) and T3, supraphysiological (simulating hyperthyroidism) in human osteoblasts derived from mesenchymal stem cells (CTMs) in the protein synthesis of RANKL and TNF-α. Osteoblasts were incubated during 72 hours in the presence of E2 at physiological dose (E2F/10 -8 M) and infraphysiological (E2I/10 -9 M), and T3 at physiological (T3F/10 -9 M) and supraphysiological (T3S/10-8 M) and quantified the bone mineralized matrix and the protein synthesis of RANKL and TNF-α by Western Blot. Statistical analysis of the data was performed by the ANOVA variance test complemented by the Tukey test, and the significance level was considered p<0.05. The treatment of E2F in E2F dose (1.96 ± 0.48, p<0.05) and E2I (3.18 ± 0.31; p <0.001) increased RANKL protein synthesis compared to control (C) (1.00 ± 0.32), and TNF-α in the dose of E2F (3.61 ± 0.45; p<0.05) and E2I (2.45 ± 0.07; p <0.05) also increased in relation to C (1.13 ± 0.19). As with E2, T3 increased RANKL protein levels in T3F (1.18 ± 0.10, p <0.05) and T3S (1.14 ± 0.004; p <0.05) compared to control (1 , 00 ± 0.02), but TNF-α decreased in dose T3S (0.82 ± 0.09; p <0.05) related to T3F (1.00 ± 0.09) and C (0, 99 ± 0.04). Thus, E2I decreased the bone mineralized matrix and increased the synthesis of both proteins studied which leads to speculation that bone resorption observed at menopause by RANKL and TNF-α pathway. On the other hand, in the mimicry of hyperthyroidism with T3S, we observed a reduction of the bone mineralized matrix, suppression of TNF-α protein synthesis and increase of RANKL, which leads us to infer that the mechanism of action for bone resorption in hyperthyroidism is by RANKL.
The regulation of bone remodeling is intermediated by local and systemic factors. The cytokines are among the local factors: Receptor Activator of Nuclear Factor Kappa B Ligand (RANKL), present in osteoblasts, and Receptor Activator of Nuclear Factor Kappa B (RANK), present in osteoclasts, in addition to other cytokines such as Tumor Necrosis Factor Alpha (TNF-α) that can act in the process of bone deposition and/or resorption in vivo. Hormones are among the systemic factors involved in bone remodeling, estrogen (E2) and triiodothyronine (T3). The aim of the study was to verify the action of E2, infraphysiological (simulating menopause) and T3, supraphysiological (simulating hyperthyroidism) in human osteoblasts derived from mesenchymal stem cells (CTMs) in the protein synthesis of RANKL and TNF-α. Osteoblasts were incubated during 72 hours in the presence of E2 at physiological dose (E2F/10 -8 M) and infraphysiological (E2I/10 -9 M), and T3 at physiological (T3F/10 -9 M) and supraphysiological (T3S/10-8 M) and quantified the bone mineralized matrix and the protein synthesis of RANKL and TNF-α by Western Blot. Statistical analysis of the data was performed by the ANOVA variance test complemented by the Tukey test, and the significance level was considered p<0.05. The treatment of E2F in E2F dose (1.96 ± 0.48, p<0.05) and E2I (3.18 ± 0.31; p <0.001) increased RANKL protein synthesis compared to control (C) (1.00 ± 0.32), and TNF-α in the dose of E2F (3.61 ± 0.45; p<0.05) and E2I (2.45 ± 0.07; p <0.05) also increased in relation to C (1.13 ± 0.19). As with E2, T3 increased RANKL protein levels in T3F (1.18 ± 0.10, p <0.05) and T3S (1.14 ± 0.004; p <0.05) compared to control (1 , 00 ± 0.02), but TNF-α decreased in dose T3S (0.82 ± 0.09; p <0.05) related to T3F (1.00 ± 0.09) and C (0, 99 ± 0.04). Thus, E2I decreased the bone mineralized matrix and increased the synthesis of both proteins studied which leads to speculation that bone resorption observed at menopause by RANKL and TNF-α pathway. On the other hand, in the mimicry of hyperthyroidism with T3S, we observed a reduction of the bone mineralized matrix, suppression of TNF-α protein synthesis and increase of RANKL, which leads us to infer that the mechanism of action for bone resorption in hyperthyroidism is by RANKL.
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Palavras-chave
Células-tronco mesenquimais, Triiodotironina, Estrógeno, RANKL, TNF-α, Osteoblastos