RESUMO
Zoledronic acid (ZOL), a nitrogen bisphosphonate (N-BP), is currently used to treat and control pediatric osteolytic diseases. Variations in the intensity of the effects and side effects of N-BPs have been reported with no clear explanations regarding their origins. We wonder if such variations could be associated with different levels of RANKL signaling activity in growing bone during and after the treatment with N-BPs. To answer this question, ZOL was injected into neonate C57BL/6J mice with different genetically-determined RANKL signaling activity levels (Opg+/+\RankTg-, Opg+/+\RankTg+, Opg+/-\RankTg-, Opg+/-\RankTg+, Opg-/-\RankTg- and Opg-/-\RankTg+ mice) following a protocol (4 injections from post-natal day 1 to 7 at the dose of 50⯵g/kg) that mimics those used in onco-pediatric patients. At the end of pediatric growth (1 and half months) and at an adult age (10â¯months), the bone morphometric and mineral parameters were measured using µCT in the tibia and skull for the different mice. A histologic analysis of the dental and periodontal tissues was also performed. At the end of pediatric growth, a delay in long bone and skull bone growth, a blockage of tooth eruption, some molar root alterations and a neoplasia-like structure associated with incisor development were found. Interestingly, the magnitude of these side effects was reduced by Opg deficiency (Opg-/-) but increased by Rank overexpression (RankTg). Analysis of the skeletal phenotype at ten months confirmed respectively the beneficial and harmful effects of Opg deficiency and Rank overexpression. These results validated the hypothesis that the RANKL signaling activity level in the bone microenvironment is implicated in the modulation of the response to ZOL. Further studies will be necessary to understand the underlying molecular mechanisms, which will help decipher the variability in the effects of N-BPs reported in the human population. SIGNIFICANT STATEMENTS: The present study establishes that in mice the RANKL signaling activity level is a major modulator of the effects and side-effects of bisphosphonates on the individual skeleton during growth. However, the modulatory actions are dependent on the ways in which this level of activity is increased. A decrease in OPG expression is beneficial to the skeletal phenotype observed at the end of growth, while RANK overexpression deteriorates it. Far removed from pediatric treatment, in adults, the skeletal phenotypes initially observed at the end of growth for the different levels of RANKL signaling activity were maintained, although significant improvement was associated only with reductions in OPG expression.
Assuntos
Conservadores da Densidade Óssea/farmacologia , Desenvolvimento Ósseo/efeitos dos fármacos , Osteoprotegerina/genética , Osteoprotegerina/metabolismo , Ácido Zoledrônico/farmacologia , Animais , Animais Recém-Nascidos , Conservadores da Densidade Óssea/administração & dosagem , Conservadores da Densidade Óssea/efeitos adversos , Técnicas de Inativação de Genes , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Ligante RANK/metabolismo , Crânio/diagnóstico por imagem , Crânio/efeitos dos fármacos , Crânio/patologia , Tíbia/diagnóstico por imagem , Tíbia/efeitos dos fármacos , Tíbia/patologia , Microtomografia por Raio-X , Ácido Zoledrônico/administração & dosagem , Ácido Zoledrônico/efeitos adversosRESUMO
Alterations in the balance of the osteoblastic-osteoclastic activity (osteopetrosis, osteolysis) have an impact on the dental development. The over activation of the osteoclastogenesis pathway RANK/RANKL/OPG in RANKTg mice produces an acceleration of tooth eruption and root elongation, suggesting this pathway could control the speed of tooth formation. Evaluate the effect of osteoclastic hyperactivity on the root formation of molars in RANKTg mice. Histologic study both descriptive and comparative of the impact of hyper-resorption of the alveolar bone in Hertwig's epithelial root sheath (HERS) of molars in both RANKTg mice and controls. This is done through the immuno-detection of matrical, epithelial and cellular proliferation proteins with histological, histoenzymology and inmunohistochemical techniques. Osteoclastic hiperactivity in alveolar bone does not alter the root structure and integrity of molars in RANKTg mice; the acceleration in root formation does not alter the HERS integrity. An area of cellular hyper-proliferation in the apical follicular tissue of HERS was found, which could regulate root growth in response to osteoclastic activity. The overexpressed RANK produces an inhibition of amelogenin expression at 5 days of age, suggesting an indirect regulation of these cells by RANK/RANKL. Exploring other molecular factors expressed in HERS, and the related engram, would make possible the use of new therapies for the control of osseous and inflammatory pathologies during root formation.
Las alteraciones en el balance de la actividad osteoblástica-osteoclástica (osteopetrosis, osteolisis) tienen un impacto en el desarrollo dental. La activación de la vía sobre la osteoclastogénesis RANK/RANKL/OPG en ratones RANKTg produce una aceleración de la erupción de los dientes y elongación de las raíces, lo que sugiere que esta vía podría controlar la velocidad de formación de los dientes. El objetivo de este estudio consiste en evaluar el efecto de la hiperactividad osteoclástica en la formación de las raíces de los molares en ratones RANKTg. Se realizó un estudio histológico descriptivo y comparativo del impacto de la hiper-reabsorción del hueso alveolar sobre la vaina epitelial radicular (de Hertwig - HERS) de molares en ratones RANKTg y controles. Se realizó la inmuno-detección de la proliferación matricial, epitelial y celular de proteínas, combinada con técnicas histológicas, inmunohistoquímicas e histoenzimológicas. La hiperactividad osteoclástica en el hueso alveolar no altera la estructura de la raíz dentaria y la integridad de los molares en ratones RANKTg; la aceleración de la formación de la raíz no altera la integridad de la misma. Se encontró un área de hiper-proliferación celular en el tejido folicular apical del HERS, que podría regular el crecimiento de la raíz en respuesta a la actividad osteoclástica. La sobreexpresión en los RANK produce una inhibición de la expresión de amelogenina a los 5 días de edad, lo que sugiere una regulación indirecta de estas células por RANK/RANKL. La exploración de otros factores moleculares expresados en HERS, y el engrama relacionado, haría posible el uso de nuevas terapias para el control de patologías óseas e inflamatorias durante la formación de la raíz dentaria.
Assuntos
Animais , Camundongos , Reabsorção da Raiz/etiologia , Reabsorção da Raiz/patologia , Reabsorção Óssea/imunologia , Imuno-Histoquímica , Perfilação da Expressão Gênica , Proliferação de Células , Modelos Animais de Doenças , Células Epiteliais , Grupos EtáriosRESUMO
Dental and periodontal tissue development is a complex process involving various cell-types. A finely orchestrated network of communications between these cells is implicated. During early development, communications between cells from the oral epithelium and the underlying mesenchyme govern the dental morphogenesis with successive bud, cap and bell stages. Later, interactions between epithelial and mesenchymal cells occur during dental root elongation. Root elongation and tooth eruption require resorption of surrounding alveolar bone to occur. For years, it was postulated that signaling molecules secreted by dental and periodontal cells control bone resorbing osteoclast precursor recruitment and differentiation. Reverse signaling originating from bone cells (osteoclasts and osteoblasts) toward dental cells was not suspected. Dental defects reported in osteopetrosis were associated with mechanical stress secondary to defective bone resorption. In the last decade, consequences of bone resorption over-activation on dental and periodontal tissue formation have been analyzed with transgenic animals (RANK (Tg) and Opg (-∕-) mice). Results suggest the existence of signals originating from osteoclasts toward dental and periodontal cells. Meanwhile, experiments consisting in transitory inhibition of bone resorption during root elongation, achieved with bone resorption inhibitors having different mechanisms of action (bisphosphonates and RANKL blocking antibodies), have evidenced dental and periodontal defects that support the presence of signals originating bone cells toward dental cells. The aim of the present manuscript is to present the data we have collected in the last years that support the hypothesis of a role of bone resorption in dental and periodontal development.
RESUMO
The MSX2 homeoprotein is implicated in all aspects of craniofacial skeletal development. During postnatal growth, MSX2 is expressed in all cells involved in mineralized tissue formation and plays a role in their differentiation and function. Msx2 null (Msx2 (-/-)) mice display complex craniofacial skeleton abnormalities with bone and tooth defects. A moderate form osteopetrotic phenotype is observed, along with decreased expression of RANKL (TNFSF11), the main osteoclast-differentiating factor. In order to elucidate the role of such an osteopetrosis in the Msx2 (-/-) mouse dental phenotype, a bone resorption rescue was performed by mating Msx2 (-/-) mice with a transgenic mouse line overexpressing Rank (Tnfrsf11a). Msx2 (-/-) Rank(Tg) mice had significant improvement in the molar phenotype, while incisor epithelium defects were exacerbated in the enamel area, with formation of massive osteolytic tumors. Although compensation for RANKL loss of function could have potential as a therapy for osteopetrosis, but in Msx2 (-/-) mice, this approach via RANK overexpression in monocyte-derived lineages, amplified latent epithelial tumor development in the peculiar continuously growing incisor.
Assuntos
Proteínas de Homeodomínio/fisiologia , Osteopetrose/fisiopatologia , Ligante RANK/fisiologia , Dente , Animais , Sequência de Bases , Primers do DNA , Proteínas de Homeodomínio/genética , Camundongos , Camundongos Knockout , Fenótipo , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Microtomografia por Raio-XRESUMO
The aim of this study was to compare the oxidation of L-[1-(13)C]phenylalanine ((13)C-PheOx) in patients with chronic liver failure due to different etiologies using L-[1-(13)C]phenylalanine breath test. Breath samples were collected before the administration of 100 mg L-[1-(13)C]phenylalanine, and every 10 min thereafter until completion of 1 h. Control subjects (n=9) presented a larger cumulative percentage of (13)C dose recovery (CPDR) than patients (n=124) with chronic liver disease, regardless of the etiology (7.5+/-0.7 vs. 4.2+/-0.2, p=0.001). No differences in CPDR were found considering the Child-Pugh (CP) class or etiology: alcoholic (CP A=7.7+/-0.7, CP B=4.1+/-0.5, CP C=2.0+/-0.3), hepatitis C virus (CP A=5.4+/-0.5, CP B=4.0+/-0.2, CP C=2.2+/-0.3), hepatocellular carcinoma (CP A=5.5+/-1.6, CP B=3.6+/-1.8, CP C=2.2+/-1.0); or cryptogenic cirrhotic patients (CP A=7.4+/-1.5, CP B=4.4+/-0.4, CP C=2.1+/-0.7). Results confirm that (13)C-PheOx decreases in patients with cirrhosis with respect to controls, notwithstanding the etiology.
Assuntos
Testes Respiratórios , Isótopos de Carbono , Hepatopatias/metabolismo , Fenilalanina/análise , Carcinoma Hepatocelular/metabolismo , Feminino , Hepatite C/metabolismo , Humanos , Fígado/metabolismo , Cirrose Hepática/metabolismo , Hepatopatias Alcoólicas/metabolismo , Neoplasias Hepáticas/metabolismo , Masculino , Pessoa de Meia-Idade , Oxirredução , Fatores de TempoRESUMO
The role of hepatitis C virus (HCV) is well established in the development of chronic hepatitis, cirrhosis and hepatic carcinoma, as well as in mixed type II cryoglobulinemia, membranoproliferative glomerulonephritis(MPGN) and porphyria cutanea tarda (PCT). Increasing evidence has been reported of a close association of HCV infection with autoimmune and hematological processes, mainly cytopenias and lymphoproliferative disorders such as B cell non-Hodgkin's lymphoma. We describe the demographic, clinical and histopathological findings of nine patients from the Mexican population with non-Hodgkin's lymphoma and HCV infection.