Estudio de las alteraciones del metabolismo mineral y de los trastornos óseos asociados a la enfermedad renal crónica

Chronic Kidney Disease (CKD) affects million people worldwide and is a risk factor for morbidity and mortality. CKD patients have poor bone mineral density due to mineral metabolism imbalance and secondary hyperparathyroidism resulting in an increased fracture incidence. Bone, despite its well-known function on mineral storage and organ protection, plays an important role as endocrine organ controlling several system functions and metabolic pathways. In this respect, bone status have been associated with cardiovascular diseases and mortality in both, the general and CKD populations. Moreover, Fibroblast Growth Factor 23 (FGF23), a phosphaturic hormone secreted by osteocytes and mature osteoblasts has been associated with increased mortality and left ventricular hypertrophy. In clinical practice, mineral abnormalities are commonly treated with calcitriol, phosphate binders and calcimimetics, to maintain plasma parathyroid hormone (PTH) and phosphate levels within the normal range. Among the distinct types of phosphate binders available, those based on magnesium have additional benefits, preventing vascular smooth muscle cells calcification. As bone disorders are involved in adverse outcomes, we consider of interest the study of the abnormalities of mineral and bone disorders associated with CKD and how calcitriol, magnesium, calcimimetic and FGF23 affect bone cells and bone homeostasis in the context of renal insufficiency. To address this issue we used animal models of renal insuficiency and in vitro models of osteoblasts and osteoclasts and we found that 1) moderate doses of calcitriol decrease osteoblast acitivity and increase mineralization in vivo whereas high doses of calcitriol impair osteogenic differentiation in vitro; 2) dietary magnesium supplementation increases osteoblast activity and may impair mineralization in vivo and magnesium supplementation promotes osteogenic differentiation in vitro through Notch signaling activation; 3) treatment with calcimimetic maintains bone turnover despite the concomitant decrease in PTH concentration in vivo and increased steogenesis and mineralization in vitro and 4) high FGF23 concentrations produce bone changes in a model of uni-nefrectomized rats and impair osteocyte maturation whereas promote osteoclast differentiation in vitro. Altogether, our results demonstrate a potential role of these molecules on bone homeostasis in CKD by targeting directly bone cells.La Enfermedad Renal Crónica (ERC) afecta a millones de personas mundialmente y es un factor de riesgo para morbilidad y mortalidad. Los pacientes con ERC tienen pérdida de densidad mineral ósea debido al desequilibrio del metabolismo mineral y al hiperparatiroidismo secundario que resulta en un incremento del índice de fracturas. El hueso, además de sus conocidas funciones como almacén de minerales y soporte y protección de órganos, juega un importante papel como órgano endocrino controlando el funcionamiento de varios sistemas y procesos metabólicos. En este sentido, el estado del hueso ha sido asociado con enfermedades cardiovasculares y mortalidad tanto en la población general como en pacientes con ERC. Además, el Factor de Crecimiento Fibroblástico 23 (FGF23), una hormona fosfatúrica secretada por osteocitos y osteoblastos maduros ha sido asociada con el incremento de mortalidad y la hipertrofia de ventrículo izquierdo. En la clínica, el tratamiento con calcitriol, quelantes de fósforo y calcimiméticos es a menudo usado para controlar los niveles plasmáticos de hormona paratiroidea (PTH) y fósforo. Entre los distintos quelantes de fósforo, los que contienen magnesio ofrecen beneficios adicionales, previniendo la calcificación de células de músculo liso vascular. Ya que los trastornos óseos están implicados en eventos adversos, consideramos de interés el estudio de las alteraciones del metabolismo mineral y los trastornos óseos asociados con la ERC y como el calcitriol, magnesio, calcimimético y FGF23 afectan las células del hueso y la homeostasis ósea en el contexto de la insuficiencia renal. Para abordar este trabajo usamos modelos animales de insuficiencia renal y modelos in vitro de osteoblastos y osteoclastos y encontramos que 1) dosis moderadas de calcitriol mejoran la mineralización y disminuyen la actividad osteoblástica in vivo mientras altas dosis bloquean la diferenciación osteogénica in vitro; 2) el alto magnesio en la dieta incrementa la actividad osteoblástica y puede afectar la mineralización in vivo, mientras que in vitro el suplemento con magnesio promueve la diferenciación osteogénica a tráves de la activación de la ruta Notch; 3) el tratamiento con calcimimético mantiene el remodelado óseo a pesar de la consecuente disminución de los nivels de PTH in vivo e incrementa la osteogénesis y la mineralización in vitro y 4) altas concentraciones de FGF23 provocan cambios en el hueso en un modelo de ratas uninefrectomizadas mientras que in vitro inhiben la maduración de los osteocitos y promueven la diferenciación osteoclástica. En general, nuestros resultados demuestran el potencial papel de estas moléculas en la homeostasis del hueso en la ERC, afectando directamente las células del hueso

Procaine Inhibits Osteo/Odontogenesis through Wnt/β-Catenin Inactivation

Introduction Periodontitis is a complex pathology characterized by the loss of alveolar bone. The causes and the mechanisms that promote this bone resorption still remain unknown. The knowledge of the critical regulators involved in the alteration of alveolar bone homeostasis is of great importance for developing molecular therapies. Procaine is an anesthetic drug with demethylant properties, mainly used by dentists in oral surgeries. The inhibitor role of Wnt signaling of procaine was described in vitro in colon cancer cells. Methods In this work we evaluated the role of procaine (1 uM) in osteo/odontogenesis of rat bone marrow mesenchymal stem cells. Similarly, the mechanisms whereby procaine achieves these effects were also studied. Results Procaine administration led to a drastic decrease of calcium content, alkaline phosphatase activity, alizarin red staining and an increase in the expression of Matrix Gla Protein. With respect to osteo/odontogenic markers, procaine decreased early and mature osteo/odontogenic markers. In parallel, procaine inhibited canonical Wnt/β-catenin pathway, observing a loss of nuclear β-catenin, a decrease in Lrp5 and Frizzled 3, a significant increase of sclerostin and Gsk3β and an increase of phosphorylated β-catenin. The combination of osteo/ odontogenic stimuli and Lithium Chloride decreased mRNA expression of Gsk3β, recovered by Procaine. Furthermore it was proved that Procaine alone dose dependently increases the expression of Gsk3β and β-catenin phosphorylation. These effects of procaine were also observed on mature osteoblast. Interestingly, at this concentration of procaine no demethylant effects were observed. PLO

Elimination of Vitamin D Signaling Causes Increased Mortality in a Model of Overactivation of the Insulin Receptor: Role of Lipid Metabolism

Vitamin D (VD) deficiency has been associated with cancer and diabetes. Insulin signaling through the insulin receptor (IR) stimulates cellular responses by activating the PI3K/AKT pathway. PTEN is a tumor suppressor and a negative regulator of the pathway. Its absence enhances insulin signaling leading to hypoglycemia, a dangerous complication found after insulin overdose. We analyzed the effect of VD signaling in a model of overactivation of the IR.We generated inducible double KO (DKO) mice for the VD receptor (VDR) and PTEN. DKO mice showed severe hypoglycemia, lower total cholesterol and increased mortality. No macroscopic tumors were detected. Analysis of the glucose metabolism did not show clear differences that would explain the increased mortality. Glucose supplementation, either systemically or directly into the brain, did not enhance DKO survival. Lipidic liver metabolism was altered as there was a delay in the activation of genes related to -oxidation and a decrease in lipogenesis in DKO mice. High-fat diet administration in DKO significantly improved its life span. Lack of vitamin D signaling increases mortality in a model of overactivation of the IR by impairing lipid metabolism. Clinically, these results reveal the importance of adequate Vitamin D levels in T1D patients

Dietary Mg Supplementation Decreases Oxidative Stress, Inflammation, and Vascular Dysfunction in an Experimental Model of Metabolic Syndrome with Renal Failure

whether a dietary Mg supplementation might attenuate vascular dysfunction through the modulation of oxidative stress and inflammation in concurrent MetS and CKD. Methods: A rat model of MetS (Zucker strain) with CKD (5/6 nephrectomy, Nx) was used. Nephrectomized animals were fed a normal 0.1%Mg (MetS+Nx+Mg0.1%) or a supplemented 0.6%Mg (MetS+Nx+Mg0.6%) diet; Sham-operated rats with MetS receiving 0.1%Mg were used as controls. Results: As compared to controls, the MetS+Nx-Mg0.1% group showed a significant increase in oxidative stress and inflammation biomarkers (lipid peroxidation and aortic interleukin-1b and -6 expression) and Endothelin-1 levels, a decrease in nitric oxide and a worsening in uremia and MetS associated pathology as hypertension, and abnormal glucose and lipid profile. Moreover, proteomic evaluation revealed changes mainly related to lipid metabolism and CVD markers. By contrast, in the MetS+Nx+Mg0.6% group, these parameters remained largely similar to controls. Conclusion: In concurrent MetS and CKD, dietary Mg supplementation reduced inflammation and oxidative stress and improved vascular function

Boletín TR-UCO. Patentes n. 18

La presente invención se refiere al uso del contenido intracelular de células madre mesenquimales (MSC) en la elaboración de un medicamento para el tratamiento de lesiones músculo-esqueléticas, entre otras la osteoartrosis. Los autores de la presente invención han evaluado el efecto beneficioso del contenido intracelular de las células mesenquimales (MSCs) en lesiones músculo esqueléticas. Además han encontrado una serie de diferencias que indican que la infusión de contenido intracelular de las células madre mesenquimales presenta ventajas frente al trasplante de estas células intactas. Las células madre mesenquimales son obtenidas de un tejido o un órgano de un individuo en un estado de crecimiento posterior al estado embrionario, p. ej. de su médula ósea