28 resultados para osteoprotegerina


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Ciências Fisiológicas - FOA

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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O nicho endosteal da medula óssea abriga as células-tronco hemopoéticas (CTH) em quiescência/autorrenovação. As CTH podem ser classificadas em dois grupos: células que reconstituem a hemopoese em longo prazo (LT-CTH) e curto prazo (CT-CTH). Investigamos, neste trabalho, os efeitos da desnutrição proteica (DP) no tecido ósseo e a participação do nicho endosteal na sinalização osteoblasto-CTH. Para tanto, utilizamos camundongos submetidos à DP induzida pelo consumo de ração hipoproteica. Os animais desnutridos apresentaram pancitopenia e diminuição nas concentrações de proteínas séricas e albumina. Quantificamos as CTH por citometria de fluxo e verificamos que os desnutridos apresentaram menor porcentagem de LT-CTH, CT-CTH e de progenitores multipotentes (PMP). Avaliamos a expressão das proteínas CD44, CXCR4, Tie-2 e Notch-1 nas LT-CTH. Observamos diminuição da expressão da proteína CD44 nos desnutridos. Isolamos as células LT-CTH por cell sorting e avaliamos a expressão gênica de CD44, CXCR4 e NOTCH-1. Verificamos que os desnutridos apresentaram menor expressão de CD44. Em relação ao ciclo celular, verificamos maior quantidade de LT-CTH nas fases G0/G1. Caracterizamos as alterações do tecido ósseo femoral, in vivo. Observamos diminuição da densidade mineral óssea e da densidade medular nos desnutridos. A desnutrição acarretou diminuição da área média das seções transversais, do perímetro do periósteo e do endósteo na cortical do fêmur dos animais. E na região trabecular, verificou-se diminuição da razão entre volume ósseo e volume da amostra e do número de trabéculas, aumento da distância entre as trabéculas e prevalência de trabéculas ósseas em formato cilíndrico. Avaliamos a expressão de colágeno, osteonectina (ON) e osteocalcina (OC) por imuno-histoquímica, e de osteopontina (OPN) por imunofluorescência no fêmur e verificamos diminuição da marcação para OPN, colágeno tipo I, OC e ON nos desnutridos. Evidenciamos, pela técnica do Picrosírius, desorganização na distribuição das fibras colágenas e presença de fibras tipo III nos fêmures dos desnutridos, além de maior número de osteoclastos evidenciados pela reação da fosfatase ácida tartarato resistente. Os osteoblastos da região femoral foram isolados por depleção imunomagnética, imunofenotipados por citometria de fluxo e cultivados em meio de indução osteogênica. Observamos menor positividade para fosfatase alcalina e vermelho de alizarina nas culturas dos osteoblastos dos desnutridos. Avaliamos, por Western Blotting, a expressão de colágeno tipo I, OPN, osterix, Runx2, RANKL e osteoprotegerina (OPG), e, por PCR em tempo real, a expressão de COL1A2, SP7, CXCL12, ANGPT1, SPP1, JAG2 e CDH2 nos osteoblastos isolados. Verificamos que a desnutrição acarretou diminuição da expressão proteica de osterix e OPG e menor expressão gênica de ANGPT1. Avaliamos a proliferação das células LSK (Lin-Sca1+c-Kit+) utilizando ensaio de CFSE (carboxifluoresceína succinimidil ester). Foi realizada cocultura de células LSK e osteoblastos (MC3T3-E1) na presença e ausência de anti-CD44. Após uma semana, verificamos menor proliferação das LSK dos desnutridos. O bloqueio de CD44 das LSK do grupo controle diminuiu a proliferação destas em três gerações. Entretanto, nos desnutridos, esse bloqueio não afetou a proliferação. Concluímos que a DP promoveu alterações no tecido ósseo e nas CTH. Entretanto, não podemos afirmar que as alterações observadas no sistema hemopoético foram decorrentes de alterações exclusivas do nicho endosteal.

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Although photodynamic therapy have been used as a useful tool over the past 30 years in oncology, few clinical trials have been conducted in dentistry. Photodynamic therapy (PDT) uses non - toxic photosensitizers and selective which are administered in target cells followed by local application of visible light, producing reactive oxygen species capable of causing cell death by apoptosis or necrosis, injured the local vasculature, and exert important effects on the im mune system. New generations of photosensitizing agents, such as nanoparticulate phthalocyanines, has shown excellent results in antitumor and antibacterial activity . In this context, the present work constitutes the first clinical protocol of local appli cation of nanoemulsion chloro - aluminum phthalocyanine (AlClFc) followed by irradiation in human gingiva, and analyzed descriptively and comparatively , by means of immunohistochemistry , the expression of RANK , RANKL , OPG and VEGF in a split - mouth model . Eight healthy volunteers with clinical indication for extraction were included in the study . Seven days before the extraction, was injected in the gingiva of participants, 5 μ M of nanoemulsion AlClFc followed by irra diation with diode laser (660nm , 7 J/cm2 ), the contralateral side was used as control. Tissue specimens were removed seven days after the TFD is performed. Tissues sample were divided into two groups (test and con trol groups) for histological and immunohistochemical analysis. Patients were monitored at days, 0, 7, 14 and 30 to assess adverse effects of the therapy. Vascular alterations were seen in gingival samples that received PDT. Areas of edema and vascular con gestion, and intense vascularization were viewed . Additionally, dystrophic calcification in subepithelial region were observed in the test group. The results showed a similar pattern of immunostaining scores of RANK, RANKL and VEGF between the test and co ntrol groups, with no statistically significant difference (p = 0.317, p = 0.777, p = 0 .814, respectively). RANK and RANKL exhibited weak or absent immunostaining in most specimens analyzed. There was n o immunostaining for OPG. VEGF showed moderate to stro ng immunostaining in specimens from the test group. In addition, the clinical study showed that therapy was well tolerated by all patients. Adverse effects were short - time and completely reversible. Taken together, the results presented in this study showe d that PDT mediated by nanoemulsion containing AlClPc is safe for clinical application in gingival tissue and suggests that a strong immunostaining for VEGF after therapy .

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The RANK / RANKL / OPG sy stem plays an important role in bone formation and resorption . This finding has been regarded as one of the m ost important advances in the understanding of bone biology with respect to osteoclastogenesis. The aim of this study was to investigate the expression of RANKL / RANK / OPG markers in reimplanted t eeth of rats, and to observe the relationship between the expression of these markers and to oth and bone resorption. Thirty male Wistar rats (Rattus norvegicus albinos) had their maxillary right incisors extrac ted , and were divided into 2 groups according to the period that the extracted teeth were kept in dry air before reimplantation : G1 (n = 15) - 5 minutes , and G2 (n = 15) - 60 minutes . After reimplantation, teeth were analyzed at intervals of 1, 3 and 7 da ys. After these experimental periods, the animals were euthanized. Longitudinal sections with 5μm thick were obtained and stained with Hematoxylin and Eosin for histological analysis , while 3μm thick sections were subjected to immunohistochemical analysis of OPG , RANK and RANKL. The results showed that the RANK / RANKL / OPG system actively participates in both the repair process, as well as tooth and bone resorption . Extr a - alveolar time of 60 minutes before replantation caused minor expressions of RANKL a nd OPG, not influencing the expression of RANK; RANKL immunostaining showed higher in both groups when compared to other biomarkers, participating in all phases of bone and tooth resorption; RANKL was associated to both osteoclastogenesis and c ell ular proliferation , and was expressed in both groups.

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Periodontal diseases, highly prevalent disease in worldwide population, manifest primarily in two distinct entities: plaque-induced gingivitis and periodontitis. Periodontitis is a chronic inflammatory disease characterized of different levels of collagen, cementum, and alveolar bone destruction. Recent experimental studies demonstrated anti-inflammatory and antirreabsortive effect of antihypertensive agents of the angiotensin II receptor blockers class on periodontal disease. The aim of this study was to evaluate the effects of azilsartan (AZT), a potent inhibitor of the angiotensin II receptor which has minimal adverse effects on bone loss, inflammation, and the expression of matrix metallo proteinases (MMPs), receptor activator of nuclear factor kB ligand (RANKL), receptor activator of nuclear factor kB (RANK), osteoprotegerin (OPG), cyclooxygenase-2 (COX-2), and cathepsin K in periodontal tissue in a rat model of ligature-induced periodontitis. Male Wistar albino rats were randomly divided into 5 groups of 20 rats each: (1) nonligated, water; (2) ligated, water; (3) ligated, 1 mg/kg AZT; (4) ligated, 5 mg/kg AZT; and (5) ligated, 10 mg/kg AZT. All groups were treated with water or AZT for 10 days. Periodontal tissues were analyzed by morphometric exam, histopathology and immunohistochemical detection of MMP-2, MMP-9, COX-2, RANKL, RANK, OPG, and cathepsin K. Levels of IL-1b, IL-10, TNF-a, myeloperoxidase (MPO), and glutathione (GSH) were determined by ELISA. Treatment with 5 mg/kg AZT resulted in reduced MPO (p˂0.05) and IL-1b (p˂0.05) levels and increased in Il-10 levels (p˂0.05). It was observed a reduced expression of MMP-2, MMP-9, COX-2, RANK, RANKL, cathepsin K, and a increased expression of OPG in the animals subjected to experimental periodontitis and threated with AZT (5 mg/kg). Conclusions: These findings suggest an anti-inflammatory and anti-reabsortive effects of AZT on ligature-induced periodontitis in rats.

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Dissertação para obtenção do grau de Mestre no Instituto Superior de Ciências da Saúde Egas Moniz

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Introducción. Los factores de crecimiento polipéptidos son una clase de mediadores biológicos naturales que regulan los eventos celulares clave en la reparación tisular, incluyendo la proliferación celular, quimiotaxis, diferenciación y síntesis de la matriz mediante la union a receptores de superficie específicos. El hueso es una fuente rica en factores de crecimiento con acciones importantes en la regulación de la formación y reabsorción ósea, entre los que se encuentran, las proteinnas morfogenéticas óseas (BMPs), el factor de crecimiento derivado de plaquets (PDGF), entre otros. El objetivo de esta investigación fue evaluar el potencial de regeneración ósea (osteoide) y osteoinducción (factores de mineralización) del rhPDGF-BB y rhBMP-2 en defectos de tamaño crítico en el cráneo de ratas Sprague-Dawley a las 4 semanas de cicatrización Materiales y Métodos. El diseño de esta investigación fue comparativo, abierto, experimental y longitudinal. La mustra consistió en 16 ratas Sprague-Dawley, las cuales se dividieron en grupos de 4, conformando así un grupo Control, un grupo Experimental 1 al cual se le colocó esponja de colágeno + 30μl a una concentración de 100 μg/ml de rhPDGFBB; un grupo Experimental 2 al que se le colocó esponja de colágeno + 30μl a una concentración de 100 μg/ml de rhBMP-2; y un grupo Experimental 3, cual cual consistió en la colocación de esponja de colágeno + 30μl a una concentración de 100 μg/ml de rhPDGF-BB + 30μl a una concentración de 100 μg/ml de rhBMP-2. Se dejó un período de cicatrización de 4 semanas y posteriormente se sacrificaron los especímenes. Resultados Resultados. Tanto rhPDGF-BB como rhBMP-2 incrementaron la producción de osteoprotegerina y de osteopontina (p<0.05). La combinación de ambos factores de crecimiento también incremento la producción de ambos factores de mineralización (p<0.01). Resultados semejantes fueron encontrados en la producción de osteoide por ambos factores. Conclusión. La combinación de ambos factores de crecimiento aumenta la regeneración ósea demostrado por el incremento en la producción de osteoide y de los factores de mineralización osteopontina y osteoprotegerina.