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)

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

Calidad de vida en pacientes con fosfatasa alcalina persistentemente baja portadores o no de mutaciones del gen ALPL

Introducción: Los niveles bajos de fosfatasa alcalina (FAlc) en suero son el sello distintivo de la hipofosfatasia, un trastorno debido a variantes patogénicas del gen ALPL. Nuestro objetivo fue determinar la calidad de vida relacionada con la salud en adultos con fosfatasa alcalina baja y explorar las diferencias entre pacientes con y sin mutaciones en ALPL. Material y métodos: Estudiamos 35 pacientes adultos con FAlc persistentemente baja en los que se excluyeron causas adquiridas y se secuenció ALPL. Se compararon con 35 controles de igual edad. Se completaron tres cuestionarios sobre dolor (Brief Pain Inventory, BPI), discapacidad física (Health Assessment Questionnaire Disability Index, HAQ-DI) y calidad de vida relacionada con la salud (36-item Short-Form Health Survey, SF-36). Resultados: Las puntuaciones medias de intensidad e interferencia del dolor en el BPI fueron mayores en el grupo de pacientes (p=0,04 y 0,004, respectivamente). Todos los dominios del instrumento HAQ tendieron a puntuar peor en los pacientes, con diferencias significativas en la puntuación de "alcance" (p=0,037) y la puntuación media general (0,23 frente a 0,09; p=0,029). Los pacientes puntuaron peor que los controles en varias dimensiones del SF-36 (rol físico, p=0,039; dolor corporal p=0,046; rol emocional, p=0,025). Sin embargo, los pacientes con y sin variantes patogénicas puntuaron de manera similar en todas las pruebas, sin diferencias significativas entre los grupos. Conclusiones: Los pacientes con niveles persistentemente bajos de FAlc tienen puntuaciones significativamente peores en dolor corporal y otras dimensiones de calidad de vida relacionadas con la salud, sin diferencias entre pacientes con y sin variantes patogénicas en el gen ALPL. Esto es consistente con la hipótesis de que estos últimos presenten mutaciones en regiones reguladoras, habitualmente no secuenciadas, del gen ALPL

Risk Factors for the Development of the Disease in Antiphospholipid Antibodies Carriers: A Long-term Follow-up Study

The natural history of antiphospholipid antibodies (aPL) carriers is not well-established. The objectives of the present study were (a) to study the probability of developing clinical criteria of antiphospholipid syndrome (APS), (b) to identify potential risk factors for developing thrombosis and/or obstetric complications, (c) to study the association between the antibody profile and development of APS, and (d) to determine the efficacy of primary prophylaxis. We retrospectively analyzed 138 subjects with positive aPL who did not fulfill clinical criteria for APS. The mean follow-up time was 138 ± 63.0 months. Thirteen patients (9.4%) developed thrombosis after an average period of 73.0 ± 48.0 months. Independent risk factors for thrombosis were smoking, hypertension, thrombocytopenia, and triple aPL positivity. Low-dose acetyl salicylic acid did not prevent thrombotic events. A total of 28 obstetric complications were detected in 92 pregnancies. During the follow-up, only two women developed obstetric APS. Prophylactic treatment in pregnant women was associated with a better outcome in the prevention of early abortions. The thrombosis rate in patients with positive aPL who do not meet diagnostic criteria for APS is 0.82/100 patients-year. Smoking, hypertension, thrombocytopenia, and the aPL profile are independent risk factors for the development of thrombosis in aPL carriers. Although the incidence of obstetric complications in this population is high (31.6%), only a few of them meet APS criteria. In these women, prophylactic treatment might be effective in preventing early abortions

Serological evolution in women with positive antiphospholipid antibodies

Objectives To explore the clinical and serological course of fertile women with positive antiphospholipid (aPL), and the factors and therapeutic implications associated with aPL negativization. Methods Retrospective study including 105 women with a positive aPL serology between 1995 and 2013 attending the obstetric autoimmune pathology clinic of a tertiary facility. Patients were classified into the following 3 groups: patients with primary antiphospholipid syndrome (pAPS, 49), patients with a positive serology for aPL, not meeting clinical criteria (42), and patients with systemic lupus erythematosus and a positive aPL serology (14). They were also classified according to the serological aPL evolution: persistently negative aPL, transiently positive serology, and persistently positive serology according to established criteria. Results After a mean follow-up of 114.4 ± 37.2 months, 59% of patients had persistently negative antibodies, while 25.7% of patients presented persistently positive aPL serology. Multivariate analysis confirmed that smoking (OR = 4; 95% CI: 1.45?11.08; p = 0.008) was an independent risk factor for positive persistence. Persistent positivity as well as a higher antibody load was associated with higher risk for further pregnancy morbidity. In 29 patients, with persistently negative serology who were asymptomatic, treatment with low-dose aspirin was discontinued. No clinical events related to APS were reported after treatment withdrawal, during the 40.95 months of follow-up. Conclusions A significant proportion of fertile women with aPL antibodies became negative during follow-up. Tobacco use and the number of positive antibodies are associated with persistently positive serology. Patients with persistently positive aPL serology suffer more obstetric complications. Treatment withdrawal might be safe in selected patients

Peripheral B-cell subset distribution in primary antiphospholipid syndrome

Background: B-cell differentiation and B-cell tolerance checkpoints may be different in antiphospholipid syndrome (APS) from systemic lupus erythematosus (SLE) and can help to understand differences between them. Our aim was to define alterations of B-cell subsets in patients with primary APS (pAPS) and to compare them with SLE patients and healthy controls (HC). Methods: Cross-sectional study including three study groups: 37 patients with pAPS, 11 SLE patients, and 21 age- and gender-matched HC. We determined the frequencies of different B-cell subsets in peripheral blood naïve and memory compartments. In addition, we measured serum B cell-activating factor (BAFF) levels and circulating pro-inflammatory cytokines, such as IL-6, by commercial ELISA and CBA, respectively. Results: Patients with pAPS showed a lower percentage of immature and naïve B cells than patients with SLE (p = 0.013 and p = 0.010, respectively) and a higher percentage of non-switched memory B cells than patients with SLE (p = 0.001). No differences either in the percentage of switched memory cells or plasma cells were found among the different groups. Serum BAFF levels were higher in SLE patients than in healthy controls and pAPS patients (p = 0.001 and p = 0.017, respectively). A significant increase in the serum BAFF levels was also observed in pAPS patients compared to HC (p = 0.047). Circulating IL-6 levels were higher in SLE and pAPS patients than HC (p = 0.036 and p = 0.048, respectively). A positive correlation was found between serum BAFF and IL-6 levels in patients with SLE but not in pAPS (p = 0.011). Conclusions: Our characterization of peripheral blood B-cell phenotypes in pAPS demonstrates different frequencies of circulating B cells at different stages of differentiation. These differences in the naïve B-cell repertoire could explain the higher number and variety of autoantibodies in SLE patients in comparison to pAPS patients, especially in those with obstetric complications

Abnormal bone turnover in individuals with low serum alkaline phosphatase

The clinical spectrum of hypophosphatasia (HPP) is broad and variable within families. Along severe infantile forms, adult forms with mild manifestations may be incidentally discovered by the presence of low alkaline phosphatase (ALP) activity in serum. However, it is still unclear whether individuals with persistently low levels of ALP, in the absence of overt manifestations of HPP, have subclinical abnormalities of bone remodeling or bone mass. The aim of this study was to obtain a better understanding of the skeletal phenotype of adults with low ALP by analyzing bone mineral density (BMD), bone microarchitecture (trabecular bone score, TBS), and bone turnover markers (P1NP and ß-crosslaps). We studied 42 individuals with persistently low serum ALP. They showed lower levels of P1NP (31.4?±?13.7 versus 48.9?±?24.4 ng/ml; p?=?0.0002) and ß-crosslaps (0.21?±?0.17 versus 0.34?±?0.22 ng/ml, p?=?0.0015) than individuals in the control group. There were no significant differences in BMD, bone mineral content, or TBS. These data suggest that individuals with hypophosphatasemia have an overall reduction of bone turnover, even in the absence of overt manifestations of HPP or low BMD. We evaluated bone mineral density (BMD), bone microarchitecture, and bone turnover markers in patients with low serum levels of alkaline phosphatase. Our results show that these patients have low bone remodeling even in the absence of BMD abnormalities, thus supporting the recommendation of avoiding antiresorptives such as bisphosphonates in these subjects

Vitamin D and antiphospholipid syndrome: A retrospective cohort study and meta-analysis

OBJECTIVES: (a) To determine serum 25-OH vitamin D (vitD) levels in primary antiphospholipid syndrome (APS) and to compare them with patients with positive antiphospholipid serology who do not meet clinical criteria for APS, and with healthy controls. (b) To analyze the association of vitD levels with both the clinical manifestations and the immunological profile of patients with primary APS. (c) To perform a meta-analysis evaluating potential differences in serum vitD levels between APS and controls as well as the frequency of vitD deficiency in APS patients. METHODS: Retrospective study including 74 patients with primary APS, 54 with positive antiphospholipid (aPL) serology not meeting clinical criteria for APS, and 215 healthy controls. We considered 30 and 10ng/ml as the thresholds for vitD insufficiency and deficiency, respectively. Meta-analysis included four case-control studies (325 primary APS patients and 507 controls) and was conducted by fitting random effects models and checked for heterogeneity. RESULTS: Median serum vitD levels were similar in the three groups: 21ng/ml in primary APS, 25ng/ml in the aPL-positive group, and 21ng/ml in controls (p = 0.115). However, we found differences in the PTH levels, being 40.4 ± 24.9pg/ml in APS, 34.1 ± 18.2pg/ml in aPL serology, and 23.4 ±12.6pg/ml in healthy controls (p < 0.001). Regarding vitD deficiency, we found significant differences across the groups: 16.2% in APS, 11.1% in patients with positive serology, and 3.7% in controls (p = 0.001). There was a trend for the presence of thrombotic events in patients with vitD deficiency (38.9% vs 19.1%, p = 0.071). The meta-analysis confirmed that the combined mean difference in serum vitD levels between APS and controls was -3.605 (p < 0.001) and that APS patients had an increased frequency of vitD deficiency, with an OR = 3.06 (95% CI: 2.12-4.43, p < 0.001). CONCLUSIONS: APS patients show higher frequency of vitD deficiency than the healthy individuals. The meta-analysis study, including three cohorts and ours, suggests that APS patients have significantly lower serum vitD levels and higher frequency of vitD deficiency than controls

Non-criteria obstetric antiphospholipid syndrome: how different is from Sidney criteria? A single-center study

This study aims to compare the demographic characteristics, clinical features, serology, and fetal-maternal outcomes between women with obstetric antiphospholipid syndrome (APS) and those with non-criteria (NC)-APS and seronegative (SN)-APS. Two-hundred and sixty-three women with APS obstetric morbidity ever pregnant were included. Of those, 66 met the APS classification criteria, 140 were NC-APS, and 57 were SN-APS. Patients with other autoimmune diseases were excluded. Adverse pregnancy outcomes (APO) included early pregnancy loss, fetal death, preeclampsia, abruptio placentae, and preterm birth. The mean age of the study group was 33.6 ± 5.3 years, and patients were followed up for 129.5 ± 81.9 months. In the NC-APS group, 31 (22.1%) did not fulfill clinical and serological criteria (Subgroup A), 49 (35%) did meet clinical but not serologic criteria (Subgroup B), and 60 (42.9%) fulfilled the serologic criteria but not the clinical ones (Subgroup C). The cardiovascular risk burden was higher in the APS group, due to a higher proportion of smoking. Patients with criteria APS received more intensive treatment than patients in the other study groups. The addition of standard of care (SoC) treatment significantly improved live birth and decreased APO in all groups. Significant clinical differences were observed between the study groups. However, when treated with SoC, fetal-maternal outcomes were similar, with a significant improvement in live births and a decrease in APO. Risk stratification in patients with obstetric morbidity associated with APS can help individualize their treatment