Epigenetics of Osteoporosis: Critical Analysis of Epigenetic Epidemiology Studies

Osteoarthritis (OA) is an age-related disease with poorly understood pathogenesis. Recent studies have demonstrated that miRNA might play a key role in OA initiation and development. We reviewed recent publications and elucidated the connection between miRNA and OA cartilage anabolic and catabolic signals, including four signaling pathways: TGF-ß/Smads and BMPs signaling, associated with cartilage anabolism; and MAPK and NF-KB signaling, associated with cartilage catabolism. We also explored the relationships with MMP, ADAMTS and NOS (NitricOxide Synthases) families, as well as with the catabolic cytokines IL-1 and TNF-a. The potential role of miRNAs in biological processes such as cartilage degeneration, chondrocyte proliferation, and differentiation is discussed. Collective evidence indicates that miRNAs play a critical role in cartilage degeneration. These findings will aid in understanding the molecular network that governs articular cartilage homeostasis and in to elucidate the role of miRNA in the pathogenesis of O

Epigenetics of Skeletal Diseases

PURPOSE OF REVIEW: Epigenetic mechanisms modify gene activity in a stable manner without altering DNA sequence. They participate in the adaptation to the environment, as well as in the pathogenesis of common complex disorders. We provide an overview of the role of epigenetic mechanisms in bone biology and pathology. RECENT FINDINGS: Extensive evidence supports the involvement of epigenetic mechanisms (DNA methylation, post-translational modifications of histone tails, and non-coding RNAs) in the differentiation of bone cells and mechanotransduction. A variety of epigenetic abnormalities have been described in patients with osteoporosis, osteoarthritis, and skeletal cancers, but their actual pathogenetic roles are still unclear. A few drugs targeting epigenetic marks have been approved for neoplastic disorders, and many more are being actively investigated. Advances in the field of epigenetics underscore the complex interactions between genetic and environmental factors as determinants of osteoporosis and other common disorders. Likewise, they help to explain the mechanisms by which prenatal and post-natal external factors, from nutrition to psychological stress, impact our body and influence the risk of later disease.Acknowledgements: Supported by a grant from the Instituto de Salud Carlos III (PI 16/0915), which can be co-funded by the European Union (FEDER Funds)

Open Course Ware: una herramienta para la enseñanza de la medicina

La iniciativa internacional Open Course Ware (OCW) se ha desarrollado en los últimos años como un procedimiento para difundir de manera libre en la internet materiales docentes generados en diversas universidades, lo cual permite el aprovechamiento de éstos por parte de profesores y alumnos de otros lugares, convirtiendo así al OCW en una nueva herramienta aplicable al aprendizaje de la medicina

Hypercalcemia in patients with rheumatoid arthritis: a retrospective study

Objetivo: Investigar la prevalencia de hipercalcemia en pacientes con artritis reumatoide (AR) y analizar las características clínicas y las causas de la hipercalcemia. Material y métodos: Estudio retrospectivo de revisión basado en casos que incluyó 500 pacientes con AR. Se identificaron los pacientes con niveles de calcio aumentados en al menos dos ocasiones. Resultados: La hipercalcemia estuvo presente en 24 de los 500 pacientes con AR (4,8%). La edad osciló entre 50 y 80 años, con una media de 68±10 años. La duración media de la enfermedad fue de 10±7 años. De los pacientes con hipercalcemia, 22 eran mujeres postmenopáusicas (92%) y solo dos eran hombres (8%). El hiperparatiroidismo se encontró en 9 pacientes de la serie; solo un paciente tenía una hipercalcemia maligna debido a un mieloma múltiple, y un caso fue consecuencia de una intoxicación por vitamina D. En un paciente la hipercalcemia parecía relacionada con el síndrome calcio-alcalino. En el resto de pacientes, la hipercalcemia fue idiopática (8/24) o el estudio fue incompleto (4/24). No se encontró una relación evidente entre la actividad de la enfermedad y la aparición de hipercalcemia. Conclusión: Al igual que sucede en la población general, el hiperparatiroidismo primario es la causa más común de hipercalcemia en pacientes con AR. En algunos pacientes no se identificaron otros trastornos causantes de hipercalcemia, lo que plantea la posibilidad de una relación causal entre la AR y la hipercalcemia.Objetive: To investigate the prevalence of hypercalcemia in patients with rheumatoid arthritis (RA) and analyze the clinical features and causes of hypercalcemia. Material and methods: Retrospective case?based review study that included 500 patients with RA. Patients with increased calcium levels on at least two occasions were identified. Results: Hypercalcemia was present in 24 of the 500 RA patients (4.8%). The age ranged between 50 and 80 years, with a mean of 68±10 years. The mean duration of the disease was 10±7 years. Of the patients with hypercalcemia, 22 were postmenopausal women (92%) and only two were men (8%). Hyperparathyroidism was found in 9 patients in the series; only one patient had malignant hypercalcemia due to multiple myeloma, and one case was a consequence of vitamin D intoxication. In one patient, hypercalcemia appeared to be related to calcium?alkali syndrome. In the remaining patients, hypercalcemia was idiopathic (8/24) or the study was incomplete (4/24). No obvious relationship was found between disease activity and the appearance of hypercalcemia. Conclusion: As in the general population, primary hyperparathyroidism is the most common cause of hypercalcemia in patients with RA. In some patients, no other disorders causing hypercalcemia were identified, raising the possibility of a causal relationship between RA and hypercalcemia

Epigenetic Mechanisms Regulating Mesenchymal Stem Cell Differentiation

Human Mesenchymal Stem Cells (hMSCs) have emerged in the last few years as one of the most promising therapeutic cell sources and, in particular, as an important tool for regenerative medicine of skeletal tissues. Although they present a more restricted potency than Embryonic Stem (ES) cells, the use of hMCS in regenerative medicine avoids many of the drawbacks characteristic of ES cells or induced pluripotent stem cells. The challenge in using these cells lies into developing precise protocols for directing cellular differentiation to generate a specific cell lineage. In order to achieve this goal, it is of the upmost importance to be able to control de process of fate decision and lineage commitment. This process requires the coordinate regulation of different molecular layers at transcriptional, posttranscriptional and translational levels. At the transcriptional level, switching on and off different sets of genes is achieved not only through transcriptional regulators, but also through their interplay with epigenetic modifiers. It is now well known that epigenetic changes take place in an orderly way through development and are critical in the determination of lineage-specific differentiation. More importantly, alteration of these epigenetic changes would, in many cases, lead to disease generation and even tumour formation. Therefore, it is crucial to elucidate how epigenetic factors, through their interplay with transcriptional regulators, control lineage commitment in hMSCs

Genetic polymorphisms of the wint receptor LRP5 are differentially associated with trochanteric and cervical hip fractures

Producción CientíficaPurpose. Epidemiological studies suggest that cervical and trochanteric hip fractures have different pathogenesis. We planned to test the hypothesis that genetic factors have different influences on both types of fractures. Methods. Ten polymorphisms of genes known to play an important role in skeletal homeostasis (estrogen receptor alpha [ESR1], aromatase [CYP19A1], type I collagen [COL1A1], and lipoprotein receptor-related protein 5 [LRP5]) were analyzed in 471 Spanish patients with fragility hip fractures. Results. Two polymorphisms of the LRP5 gene (rs7116604 and rs3781600) were associated with the type of fracture (p-value 0.0085 and 0.0047, respectively). The presence of rare alleles at each locus was associated with trochanteric fractures over cervical fractures (OR 1.7 in individuals with at least one rare allele at rs7116604 or rs3781600 loci, in comparison with the common homozygotes). Considering individuals bearing the four common alleles as reference, the OR for trochanteric fractures was 1.6 in those with 1 or 2 rare alleles, and 7.5 in those with 3 or 4 rare alleles (p-value for trend 0.0074), which is consistent with an allele-dosage effect. There were no significant differences in the frequency distributions of the ESR1, CYP19A1 and COL1A1 genotypes between trochanteric and cervical fractures in either the original group or in an extended group of 818 patients. Conclusions. These results suggest LRP5 alleles influence the type of hip fractures. They support the view that different genetic factors are involved in cervical and trochanteric fractures, which should be taken into consideration in future genetic association studies

Vertebroplasty and kyphoplasty as treatment for osteoporotic vertebral fractures

Summary Over the last decade vertebroplasty and kyphoplasty have become popular as therapeutic options for the treatment of vertebral fractures. In fact, numerous non-controlled studies have indicated that both procedures are very efficacious for the control of pain associated with fractures. However, some recently published randomised trials have cast doubt on the true effectiveness of these procedures. On the other hand, certain observations have suggested that the increase in the rigidity which is produced by the injection of metacrylate into a vertebral body could facilitate the collapse of the adjacent vertebra. Therefore, vertebroplasty and kyphoplasty should not be considered as a routine theraputic measure, but should be limited to carefully selected patients, in whom the potential benefits surpass the risks and costs of the procedure. In any case, the patients should be put on a global treatment programme which includes pharmaceutical measures and non-pharmaceutical care to reduce the risk of future vertebral and peripheral fractures. Various clinical trials have recently been published which were supposed to be an important contribution to knowledge regarding the effectiveness of vertebroplasty. The results have been rather contradictory both within themselves, and with earlier observational studies. For this reason it is worth reviewing this questions with the intention of helping clinicians who need to take decisions on the treatment of patients with osteoporotic fractures. We have not dealt with the possible utility vertebroplasty in other processes, such as fractures caused by tumours or by trauma