MicroARN circulantes y su potencialidad como futuros biomarcadores óseos / Circulating microRNAs and their potential use as future bone biomarkers / MicroRNAs circulantes e a sua potencialidade como futuros biomarcadores ósseos

Resumen El remodelamiento óseo es ejercido por la actividad de osteoblastos y osteoclastos y puede evaluarse por marcadores bioquímicos de formación y resorción ósea. Sin embargo, el nivel de los marcadores óseos está sometido a una enorme cantidad de variables y, además, carece o presenta escaso valor pronóstico. Los microARN (miARN) fueron recientemente estudiados como una alternativa potencial para ser utilizados como nuevos marcadores óseos. Los miARN son pequeñas moléculas de ARN no codificantes (15-25 nucleótidos) que, a través de la inhibición o degradación de ARN mensajeros, modifican una serie de funciones biológicas. Los miARN específicos de hueso ejercen funciones reguladoras sobre factores transcripcionales involucrados en la osteoblastogénesis y osteoclastogénesis, modificando el remodelamiento óseo. La mayoría de los miARN permanecen dentro de la célula, pero algunos son liberados a la circulación donde pueden ser dosados. Los miARN circulantes presentan gran estabilidad en fluidos biológicos, lo que los hace potenciales candidatos a ser utilizados como nuevos biomarcadores óseos. Cambios en el patrón normal de miARN circulantes específicos de hueso reflejarán modificaciones en el metabolismo óseo y señalan el posible inicio o progresión de enfermedades óseas, como la osteoporosis. Si bien es promisorio, el uso en la práctica clínica de los miARN específicos circulantes como nuevos biomarcadores óseos, ello implica primeramente cumplir con una serie de requisitos que permitan estandarizar las condiciones preanalíticas, analíticas y posanalíticas de estas moléculas. La presente revisión brinda información reciente sobre los estudios clínicos tendientes a determinar el posible uso de los miARN circulantes como nuevos biomarcadores óseos, ya que cuentan con elevada sensibilidad y especificidad diagnósticas, valor predictivo positivo y valor predictivo negativo.

Abstract Osteoblasts and osteoclasts activity determines the level of the bone remodelling process which can be assessed by biochemical markers of bone formation and resorption. However, bone marker levels are subject to a series of variables resand, furthermore, they lack or have little prognostic values. MicroRNAs (miRNAs) were recently studied as a potential alternative to be used as new bone biomarkers. The miRNAs are endogenous small noncoding RNA molecules (15-25 nucleotides) that regulate many biological functions by inhibiting or degrading specific messenger RNAs. Bone-specific miRNAs exert regulatory functions on key transcriptional factors involved in osteoblastogenesis and osteoclastogenesis, modifying the bone remodelling process. Most miRNAs remain within the cell, but some of them are released into circulation. Circulating miRNAs show great stability in biological fluids, which makes them excellent candidates to be used as new bone biomarkers. Modifications in the normal pattern of bone-specific circulating miRNA might reflect changes in bone metabolism, signalling the possible onset or progression of bone diseases, such as osteoporosis. Although promising, the use of specific circulating miRNAs as new bone biomarkers in clinical practice implies fulfilling a series of requirements that lead to standardising the pre-analytical, analytical and post-analytical conditions of these molecules. The present review gives an overview on the clinical studies related to the possible use of specific circulating miRNAs as new bone biomarkers.

Resumo A remodelação óssea é exercida pela atividade dos osteoblastos e osteoclastos e pode ser avaliada para a medição dos marcadores bioquímicos de formação e reabsorção óssea. No entanto, o nível dos marcadores ósseos está sujeito a grande quantidade de variáveis e, além disso, carece ou tem pouco valor prognóstico. Os microARN (miARN) foram estudados recentemente como uma alternativa potencial para serem utilizados como novos marcadores ósseos. Os MicroRNAs (miRNAs) são pequenas moléculas de RNA não codificantes (15-25 nucleotídeos) que, através da inibição ou degradação de RNA mensageiros modificam uma série de funções biológicas. Os miRNAs específicos de osso exercem funções reguladoras sobre fatores transcricionais envolvidos na osteoblastogênese e na osteoclastogênese, modificando o processo de remodelação óssea. A maioria dos miRNAs permanece dentro da célula, mas de RNA mensageiros alguns são liberados na circulação, onde podem ser determinados bioquimicamente. Os miRNAs circulantes apresentam grande estabilidade em fluidos biológicos, o que os torna excelentes candidatos para serem usados como novos biomarcadores ósseos. Mudanças no padrão normal de miRNA circulantes específicos do osso mostrarão mudanças no metabolismo ósseo, sinalizando o possível início ou progressão de doenças ósseas, como osteoporose. Embora promissor, o uso de miRNAs específicas circulantes na prática clínica como novos biomarcadores ósseos, implica primeiramente, atender uma série de requisitos que permitem padronizar as condições pré-analíticas, analíticas e pós-analíticas dessas moléculas. A presente revisão fornece informações recentes sobre estudos clínicos destinados a determinar o possível uso dos miRNAs circulantes como novos biomarcadores ósseos, visto que contam com elevada sensibilidade e especificidade diagnósticas, valor preditivo positivo e valor preditivo negativo.

THE THREE KEY PLAYERS IN OSTEOIMMUNOLOGY: RANK, RANKL AND OSTEOPROTEGERIN.

The RANK, RANKL and OPG interaction plays a major role in bone resorption and remodelling. The history dates back to mid 1990s when the RANK/ RANKL interaction was found to mediate osteoblastic stromal cells to stimulate osteoclastic bone resorption. This interaction was found to induce several cytokines including the TNF superfamily, thereby activating the pathways of bone remodelling. The Osteoprotegerin (OPG) prevents the binding of RANKL to RANK, thereby preventing the excessive bone resorption. When there is an imbalance in the levels of RANK/RANKL/OPG, the metabolic activity of the bone cells gets altered and thus there is loss of balance between bone formation and resorption. Thus, studying the inter – relationship between RANK, RANKL and OPG becomes critical for assessing the osteoblastic and osteoclastic activity

Micro RNAs In Periodontal Disease – A Review

@#microRNAs (miRNAs) constitute a family of small, non-coding RNA molecules that regulate gene expression and protein expression. microRNAs have influence on a broad range of physiologic and pathologic conditions. They are also considered as promising biomarkers especially when they are secreted extracellularly. In the inflammatory pathways, they dysregulate the molecular processes and contribute to the development of chronic inflammatory diseases including periodontitis. In this review, we provide an overview of miRNA characteristics, biogenesis, mechanisms of action and profiling methods. In addition, the role of miRNAs in the pathobiology of periodontitis, especially those pertaining to the cellular and molecular pathways of inflammation has been considered to enhance our understanding of the pathobiology of periodontitis.

Bone marrow adipose tissue——A kind of special adipose tissue / 中华内分泌代谢杂志

Bone marrow adipose tissue (MAT) is formed by the accumulation of adipocytes in the bone marrow cavity. Previously, the function of MAT is mainly considered to be filled with bone marrow cavity for the mechanical support. However,with the in-depth study of MAT,it has been gradually understood that MAT is not only a part of the bone marrow microenvironment,may also be a new endocrine "organ". The main component of bone marrow adipocytes(BMA) plays a regulatory role in bone marrow and systemic metabolism through the autocrine and paracrine secretion of adiponectin, leptin, interleukin-6, and a series of cytokines. Though its biological characteristics are somewhat similar with white fat adipose tissue(WAT) and brown adipose tissue(BAT),there are some significant differences,so MAT is thought to be a special adipose tissue. MAT is also involved in the development of hematological diseases,metabolic diseases,degenerative diseases,and may affect their outcomes. MAT may be the auxiliary diagnostic criteria and treatment targets of such diseases. This article will review the MAT's own biological characteristics,the differences and associations among three types of adipose tissue and the link between MAT and the diseases,which aims to explore the new research direction through the profound understanding of MAT.

Osteoporosis and periodontitis: a bidirectional relationship / Osteoporose e periodontite: uma relação bidirecional

Osteoporosis is a condition of compromised bone strength that predisposes an individual to increased risk of fracture and is a major cause of morbidity in older susceptible individuals. Osteoporosis is related to various endocrinal abnormalities, metabolic and nutritional factors, postmenopausal hormonal changes and consumption of certain drugs such as cortisone. Emerging clinical and molecular evidence suggests that inflammation also exerts significant influence on osteoporotic bone changes. Numerous pro-inflammatory cytokines have been shown to be associated with regulation of osteoblast and osteoclast differentiation. Chronic inflammatory conditions causing immune system remodeling may serve as pathological risk factors for osteoporosis. The present article reviews the current perspective on the interaction between bone morphology and immune system in the inflammatory condition (periodontitis), unleashing the link between two chronic conditions. (AU)

A osteoporose é uma condição de resistência óssea comprometida que predispõe um indivíduo ao risco aumentado de fratura e é uma das principais causas de morbidade em indivíduos susceptíveis mais velhos. A osteoporose está relacionada a várias anomalias endócrinas, fatores metabólicos e nutricionais, alterações hormonais pós-menopausa e consumo de certos medicamentos como a cortisona. Evidências clínicas e moleculares emergentes sugerem que a inflamação também exerce uma influência significativa sobre as alterações ósseas osteoporóticas. Numerosas citoquinas pró-inflamatórias demonstraram estar associadas à regulação da osteoblastos e da diferenciação osteoclástica. As condições inflamatórias crónicas, que provocam a remodelação do sistema imunitário, podem servir como factores de risco patológicos para a osteoporose. O presente artigo apresenta uma revisão da perspectiva atual sobre a interação entre a morfologia óssea e o sistema imunológico na condição inflamatória (periodontite), desencadeando a ligação entre duas condições crônicas (AU)

Conexiones entre tejido óseo y tejido graso: efecto de la obesidad sobre la salud ósea / Bone and fat connection: obesity effect on bone health / Conexões entre tecido ósseo e tecido gorduroso: efeito da obesidade na saúde óssea

La prevalencia de dos desórdenes crónicos como la osteoporosis y la obesidad se encuentra en aumento. La fisiopatología de ambas alteraciones metabólicas es multifactorial e incluye factores genéticos, factores ambientales y hormonales. Diversos estudios clínicos y experimentales demuestran la existencia de una interacción entre el tejido adiposo y el esqueleto, similar a la que ocurre entre las patologías mencionadas. Si bien se pensaba que la obesidad protegía al hueso, actualmente se postula que un exceso de tejido graso, fundamentalmente grasa abdominal, sería un factor de riesgo para el desarrollo de osteoporosis y fracturas por fragilidad. Diversos factores secretados por el tejido graso incrementados por efecto de la obesidad jugarían un rol clave en la salud ósea. Las adipoquinas, citokinas y ácidos grasos libres regulan el remodelamiento óseo, disminuyendo la formación e incrementando la resorción, al mismo tiempo que inducen estrés oxidativo e hiperglucemia, que exacerba el efecto negativo sobre la masa ósea. Esta revisión trata de profundizar el conocimiento de las interacciones entre hueso y tejido adiposo y de las implicancias clínicas que surgen de la interrelación entre obesidad y osteoporosis.

Osteoporosis and obesity are chronic disorders that are increasing in prevalence. The pathophysiology of these diseases is multifactorial and it includes genetic, environmental and hormonal determinants. Basic and clinical studies support an important interaction between adipose tissue and the skeleton similar to that found in osteoporosis and obesity. The belief that obesity is protective for bone has recently been revised. In fact, excess of fat mass might be a risk factor for osteoporosis and fragility fractures. Increasing evidence seems to indicate that different factors released by the fat tissue could play a key role in skeletal health. Adipokines, cytokines and free-fatty acids secreted by the obese fat mass can regulate bone remodelling decreasing bone formation and increasing bone resorption. Moreover they increase oxidative stress, increasing even more the negative effect on bone mass. This review considers literature data to understand bone-fat interactions and the clinical implications of linking obesity to osteoporosis.

A prevalência de duas doenças crônicas, como a osteoporose e a obesidade estão aumentando. A fisiopatologia de ambas as doenças metabólicas é multifatorial e inclui fatores genéticos, fatores ambientais e hormonais. Estudos clínicos e experimentais demonstram a existência de interação entre o tecido adiposo e o esqueleto, semelhante ao encontrado nas patologias mencionadas. Embora exista a crença de que a obesidade protegia o osso, atualmente se postula que um excesso de tecido gorduroso, fundamentalmente gordura abdominal seria um fator de risco para desenvolver osteoporose e fraturas por fragilidade. Diversos fatores secretados pelo tecido gorduroso aumentado por efeito da obesidade teria um papel chave na saúde óssea. As adipocinas, citocinas e ácidos graxos livres regulam a remodelação óssea, diminuindo a formação e aumentando a reabsorção, ao mesmo tempo que eles induzem estresse oxidativo e hiperglicemia, aumentando ainda mais o efeito negativo sobre a massa óssea. Esta revisão visa aprofundar o conhecimento das interações entre o osso e o tecido adiposo e nas implicações clínicas que surgem da interação entre obesidade a osteoporose.

Quantification of Bone Histomorphometric Parameters Using the Weibel Technique in Animals

Bone histomorphometric measurements are required to understand the efficacy of treatment on bone remodelling. Previous studies used the Weibel technique as a quantitative stereological method to determine bone cellular and dynamic changes. However, there was no description on how this technique was applied. This studyaimed to provide a full picture about the utilization of the Weibel technique to measure static and dynamic bone histomorphometric indices. Technical expertise, processing of bone samples, randomization of the trabecular sections and an adequate number of analysed images for each section are required to achieve reliable results with a low possibility of errors.

Mechanostat of bone remodelling under dynamic loads / 医用生物力学

Objective To discuss the mechanostat of bone remodeling under dynamic loads. Methods By analysis on mechanostat of bone remodeling and absorption from the idea of mechanical fatigue strength theory, the mechanostat of bone remodeling under dynamic loads was developed. Damage was selected as the mechanical stimulus under dynamic loads and the model of bone remodeling under dynamic loads was proposed. Physical exercise for prevention and treatment of osteoporosis was simulated to analyze the biomechanical phenomenon why the osteogenesis effect under dynamic loads seems better than that under static loads. Results The biomechanical phenomenon as mentioned above was reasonably explained. An increase of 10%-30% in physical exercise could cause an increase of 3.13%-8.61% in bone mineral density. Conclusions The mechanostat of bone remodeling under dynamic loads will provide theoretical guidance for using mechanical vibration to treat or prevent diseases related to bone metabolism, which is the supplement and improvement for mechanostat of bone remodeling.

Role of periostin in bone metabolism / 中华内分泌代谢杂志

Periostin is preferentially expressed in the periosteum, which covers a large majority of bones.Periostin has been reported to promote osteoblast proliferation, adhesion, and differentiation, involving bone repair process, response to mechanical stimulation and parathyroid hormone (PTH), regulating bone development/ remodeling and bone strength.Circulating periostin may serve as a candidate of biological markers for bone metabolism.

Avaliação do metabolismo mineral de pacientes com doença renal crônica em diálise peritoneal: correlação entre parâmetros clínicos, bioquímicos e de histologia óssea / Evaluation of mineral metabolism in peritoneal dialysis patients: correlation between bone histology, clinical features and biochemical parameters

Introdução: Os distúrbios minerais e ósseos da doença renal crônica (DMO-DRC) são influenciados por vários fatores, como idade, etiologia da DRC, toxinas urêmicas e modalidade dialítica. Os DMO-DRC são bem descritos em pacientes tratados com hemodiálise (HD). No entanto, na diálise peritoneal (DP) os estudos são escassos e, na maioria deles, não há dados de histologia óssea. Objetivos: caracterizar os DMO-DRC em uma coorte de pacientes em DP; comparar os resultados com aqueles obtidos da HD; e analisar o desempenho de marcadores séricos para o diagnóstico das doenças de alto e baixo remodelamento ósseo. Métodos: quarenta e um pacientes tratados com DP submeteram-se a avaliação clínica, bioquímica e biópsia óssea. Resultados: a doença óssea adinâmica (DOA) foi o tipo de osteodistrofia renal (OR) predominante, correspondendo a 49% da amostra. Ao se analisar separadamente diabéticos e não diabéticos, a prevalência de DOA foi de 77,7% no primeiro grupo e 26% no segundo (p=0,001). Na comparação entre DP e HD, observou-se que os pacientes do primeiro grupo apresentavam 25(OH) vitamina D mais baixa, mineralização óssea mais comprometida e melhor volume ósseo. A fosfatase alcalina óssea (FAO) apresentou a melhor sensibilidade e especificidade tanto para o diagnóstico de alto, quanto de baixo remodelamento ósseo. Conclusões: a DOA é o tipo de OR mais prevalente na DP. No entanto, a influência do diabetes como fator de risco parece ser maior do que a própria modalidade dialítica.

Introduction: Chronic kidney disease - mineral bone disorder (CKD-MBD) is a complex syndrome influenced by various factors, such as age, CKD etiology, uremic toxins and dialysis modality. CKD-MBD has been extensively studied in hemodialysis (HD) patients. However, for peritoneal dialysis (PD), only a few, older studies exist, most of which contain no bone biopsy data. The present study sought to: characterize CKD-MBD in a cohort of prevalent PD patients; compare the results with that obtained from HD patients; and analyse performance of bone turnover serum markers to make the diagnosis of high or low bone turnover disease in PD patients. Methods: Forty-one PD patients underwent to a clinical evaluation, biochemical analysis and bone biopsy. Results: The most prevalent pattern of renal osteodystrophy (ROD) was adynamic bone disease (ABD), comprising 49% of the sample population. When we separately analyzed diabetic and non-diabetic patients, the ABD prevalence was 77.7% in the former group and 26% in the latter group (p=0.001). The comparison between DP and HD patients revealed low 25(OH) vitamin D level, worst bone mineralization and better bone volume parameters in the former group. Bone alkaline phosphatase (BAP) demonstrated the best sensitivity and specificity values to detect both high and low turnover disease. Conclusion: ABD is the most frequent type of ROD. However, the effect of diabetes on the development of ABD is more important than the dialysis modality itself.

Influence of Infliximab on Cytokines Network and Markers of Bone Remodeling in Rheumatoid Arthritis Patients

PURPOSE: Our aim was to determine the effects of infliximab on bone mineral metabolism in rheumatoid arthritis (RA) patients and analyze the relationship between inflammatory markers of acute phase thought to play a major role in bone remodeling. MATERIALS AND METHODS: 36 patients with established RA were investigated. All patients underwent physical examination and blood and urinary analysis at baseline, 2 weeks, 14 weeks, 6 months and 12 months after the initiation of treatment. The serum levels of: tumor necrosis factor alpha (TNF-alpha), tumor necrosis factor alpha receptor 1 (TNFR1), TNFR2, interleukin 6 (IL-6), IL-17, IL-23 and markers of bone remodeling such as osteocalcin (BGP), deoxypyridynoline (Dpd), and N-telopeptide of type I collagen (NTx) were measured by ELISA. RESULTS: The results showed significant decrease of all the above cytokines levels in RA patients in comparison with those after 2 weeks of treatment. After 6 months, the markers of bone formation and resorption decreased compared to baseline values. We found positive correlation between the levels of NTx and the levels of IL-6, IL-17 and TNFR1, and between the levels of Dpd and IL-6 and Dpd and TNFR2, whereas negative correlation between BGP and IL-23. After 12 months the positive association was found at the BGP level and IL-6 as well as Dpd and the level of IL-6. We also observed a positive relation between Dpd and TNF-alpha and negative between BGP and TNFR1. CONCLUSION: We suggest that infliximab treatment may limit the risk of osteoporosis in RA patients.

Pulp and periodontal tissue changes following rapid tooth retraction by periodontal distraction in young adult dogs / 대한치과교정학회지

OBJECTIVE: The aim of this study was to evaluate pulp and periodontal changes following rapid tooth retraction by periodontal distraction after bone undermining surgery in young adult dogs. METHODS: After extraction of second premolars, the interseptal bone mesial to the upper 3rd premolar was undermined. After activating the distraction appliance at 0.5 mm/day for six days, the dogs were sacrificed at 0, 1, 3, 5, 7, and 9 weeks during the consolidation period. Tissue changes of periodontium and pulp were evaluated radiologically, histologically, and immunohistochemically. RESULTS: Digital subtraction radiography showed active bone formation in the stretched periodontal ligament from 0 - 4 weeks. Resorption of the alveolar bone, appearance of osteoclasts, and infiltration of inflammatory cells were observed just after the activation period at the pressure side, and distinctive bone formation was seen in the tension side of the periodontal ligament from 1 week. New bone formation was active at 1 - 3 weeks. The expression of calcitonin gene-related peptide in the experimental group was increased at the alveolar bone and pulp, and periodontal ligament at the pressure side from 0 - 1 week, and it decreased after 5 weeks to become similar to that of the control group. CONCLUSIONS: The results showed that rapid tooth movement using periodontal distraction can be new form of orthodontic tooth movement for accelerating normal bone formation.