Sequential management of postmenopausal health and osteoporosis: An update.

Increased life expectancy means that women are now in a hypoestrogenic state for approximately one-third of their lives. Overall health and specifically bone health during this period evolves in accordance with aging and successive exposure to various risk factors. In this review, we provide a summary of the approaches to the sequential management of osteoporosis within an integrative model of care to offer physicians a useful tool to facilitate therapeutic decision-making. Current evidence suggests that pharmacologic agents should be selected based on the risk of fractures, which does not always correlate with age. Due to their effect on bone turnover and on other hormone-regulated phenomena, such as hot flushes or breast cancer risk, we position hormone therapy and selective estrogen receptor modulators as an early postmenopause intervention for the management of postmenopausal osteoporosis. When the use of these agents is not possible, compelling evidence supports antiresorptive agents as first-line treatment of postmenopausal osteoporosis in many clinical scenarios, with digestive conditions, kidney function, readiness for compliance, or patient preferences playing a role in choosing between bisphosphonates or denosumab during this period. For patients at high risk of osteoporotic fracture, the "anabolic first" approach reduces that risk. The effect on bone health with these bone-forming agents or with denosumab should be consolidated with the subsequent use of antiresorptive agents. Regardless of the strategy, follow-up and treatment should be maintained indefinitely to help prevent fractures.

Risk factors for a second nonsimultaneous hip fracture in a prospective cohort study.

INTRODUCTION: The risk factors for a second nonsimultaneous hip fracture are unclear, and in general, it is empirically assumed that they are similar to those associated with the first hip fracture. We aimed to determine the incidence of a second hip fracture and define the characteristics of the patients sustaining the event in a prospective cohort study in a Spanish population. MATERIALS AND METHODS: We conducted a multicentric, prospective cohort study in a representative sample of 45 hospitals from 15 autonomic regions in Spain. In total, the study included 994 patients. One hundred and one patients presented a nonsimultaneous contralateral hip fracture, constituting the intervention group. The remaining 893 patients presenting with a hip fracture formed the control group. The main outcome measures of this study were sociodemographic characteristics of the patient, comorbid conditions, and baseline and postfracture clinical outcomes (inpatient complications and acute mortality). RESULTS: The key fracture risk factors were a history of fragility fractures, the need for assistance when walking outdoors and a history of falls. There were no associations between the groups in any of the common fragility risk factors, including rheumatoid arthritis, secondary osteoporosis, or steroid consumption. The results showed that patients suffering a nonsimultaneous hip fracture had an increased risk of mortality after discharge compared with the control group. CONCLUSION: A nonsimultaneous second hip fracture leads to a near-significant increase in four-month mortality. In our study, this fracture was associated with a history of falls, prior fragility fractures, and the need for a walking aid.

Functional Analyses of Four CYP1A1 Missense Mutations Present in Patients with Atypical Femoral Fractures.

Osteoporosis is the most common metabolic bone disorder and nitrogen-containing bisphosphonates (BP) are a first line treatment for it. Yet, atypical femoral fractures (AFF), a rare adverse effect, may appear after prolonged BP administration. Given the low incidence of AFF, an underlying genetic cause that increases the susceptibility to these fractures is suspected. Previous studies uncovered rare CYP1A1 mutations in osteoporosis patients who suffered AFF after long-term BP treatment. CYP1A1 is involved in drug metabolism and steroid catabolism, making it an interesting candidate. However, a functional validation for the AFF-associated CYP1A1 mutations was lacking. Here we tested the enzymatic activity of four such CYP1A1 variants, by transfecting them into Saos-2 cells. We also tested the effect of commonly used BPs on the enzymatic activity of the CYP1A1 forms. We demonstrated that the p.Arg98Trp and p.Arg136His CYP1A1 variants have a significant negative effect on enzymatic activity. Moreover, all the BP treatments decreased CYP1A1 activity, although no specific interaction with CYP1A1 variants was found. Our results provide functional support to the hypothesis that an additive effect between CYP1A1 heterozygous mutations p.Arg98Trp and p.Arg136His, other rare mutations and long-term BP exposure might generate susceptibility to AFF.

Thromboembolic, cardiovascular and overall mortality risks of aromatase inhibitors, compared with tamoxifen treatment: an outpatient-register-based retrospective cohort study.

BACKGROUND: Tamoxifen (TAM) and aromatase inhibitor (AI) therapies have been associated with increased risk of thromboembolic and cardiovascular events, respectively, in addition to other side effects. This study analysed the risk of these events and the overall survival (OS) benefit in breast cancer patients treated with AI, compared with TAM-treated patients, in a large population-based cohort. METHODS: This observational cohort study included women diagnosed with breast cancer and treated with TAM or AI. Data were extracted from primary care records in a population database (SIDIAP, System for the Development of Research in Primary Care). Incidence rates of study outcomes are reported. Survival analyses included Kaplan-Meier estimation and Cox proportional hazards models. Sensitivity analysis was carried out, using Fine and Gray models to account for competing risk of death. Confounding was minimized using propensity score adjustment and inverse probability weighting (IPW) adjustment. RESULTS: Data from 3082 postmenopausal women treated with TAM, and 18,455 treated with AI, were available. Adjusted hazard ratios (HRs) [95% confidence interval (CI)] for AI users, compared with TAM group, were 0.93 (95%CI 0.69-1.26) for thromboembolic events (TEEs); 1.13 (95%CI 0.79-1.63) for cardiovascular events, and 0.76 (95%CI 0.70-0.82) for mortality. Additional analyses using competing risk analysis had similar results, while IPW adjustment showed a potential risk of pulmonary embolism (PE) [2.26 (95%CI 1.02-4.97)] in AI-treated patients. CONCLUSIONS: AI users had >20% lower all-cause mortality compared with TAM users, without increasing risk to experience cardiovascular and TEEs. This would locate AI therapy on the first line in clinical practice. Thus, AI might be the most preferable option in adjuvant hormonal therapy choice.

Bone tissue quality in patients with monoclonal gammopathy of uncertain significance.

INTRODUCTION: Monoclonal gammopathy of uncertain significance (MGUS) is highly prevalent in older adults and affects bone structure, with osteoporosis and increased risk of fractures in up to 14% of affected patients. Dual-energy X-ray absorptiometry (DXA), the standard technique for diagnosing osteoporosis, is ineffective to reveal microstructure and bone quality in this disease. MATERIALS AND METHODS: We conducted a cross-sectional study of patients with MGUS, recruited consecutively from the Hematology and Internal Medicine Departments of Hospital del Mar, Barcelona, between January 2011 and January 2018. Medical records, clinical results and spinal X-ray images were collected. Bone mineral density (BMD) at hip and spine was measured by DXA and Bone Material Strength index (BMSi) by impact microindentation on the tibial mid-shaft. RESULTS: Thirty-nine patients with MGUS and 65 age-matched controls without previous fractures were included. In the MGUS group, 11 (28.2%) patients had prevalent fractures, nearly half of them vertebral (n = 5, 45.45%). Compared to controls, MGUS patients had significantly lower BMSi, a mean (SD) of 70.72 (9.70) vs. 78.29 (8.70), p = 0.001, and lower spinal BMD values (0.900 [0.159] vs. 1.003 [0.168], respectively, p = 0.012), but no significant differences at femoral neck and total hip. No association was observed between BMSi and DXA. Bone remodeling markers (procollagen type-1 N propeptide, bone-alkaline phosphatase and C-terminal telopeptide of type I collagen) did not differ between the two groups. CONCLUSIONS: Spinal BMD and mechanical properties of bone tissue, as measured by impact microindentation, were impaired in patients with MGUS. These changes in bone tissue mechanical resistance were independent of DXA levels.

Bone material strength index is associated with prior fracture in men with and without moderate chronic kidney disease.

BACKGROUND: Patients with chronic kidney disease (CKD) are at high risk for fracture. The ability of bone mineral density (BMD) to predict fractures in CKD patients has been inconsistent. Other measures such as trabecular bone score (TBS) and impact microindentation (IMI) may be more useful in this group. This study aimed to determine if TBS or IMI values differed between men with and without CKD and examine associations between prior fracture, TBS and IMI values. METHODS: Men (n = 343, age 33-96 yr) from the Geelong Osteoporosis Study were included. Femoral neck (FNBMD) and lumbar spine BMD (LSBMD) were measured using DXA (Lunar ProdigyPro). TBS was determined from lumbar spine scans (TBS iNsight software Version 2.2). IMI values (bone material strength index; BMSi) were measured using an OsteoProbe. CKD was defined as an eGFR<60 mL/min/1.73m2 (n = 53). Prior low trauma fractures (n = 37) were ascertained from radiological reports. Associations were examined using binary logistic regression, adjusting for potential confounders. Interaction terms were tested in all models. RESULTS: Men with CKD tended to have a higher likelihood of prior fracture (adjusted OR 2.27, 95%CI 1.02-5.01). Higher BMSi was associated with a lower likelihood of prior fracture (adjusted OR for 1SD increase: 0.70; 95%CI 0.51-0.97). This association was sustained after adjustment for FNBMD (OR 0.68; 95%CI 0.49-0.96) or LSBMD (OR 0.69; 95%CI 0.49-0.95). No interaction was detected between BMSi and CKD (p = 0.898). No associations were detected between FNBMD, LSBMD or TBS and prior fracture in either population and there were no interactions with CKD for FNBMD, LSBMD or TBS. CONCLUSIONS: BMSi was associated with prior fracture in men with and without CKD, however, FNBMD, LSBMD and TBS were not. Lack of an interaction term suggests that BMSi performed similarly in identifying the likelihood of prior fracture, regardless of CKD status. IMI may have clinical utility for assessing fracture risk in patients with CKD.

Increased Fracture Risk in Women Treated With Aromatase Inhibitors Versus Tamoxifen: Beneficial Effect of Bisphosphonates.

Aromatase inhibitors have been associated with accelerated bone loss and an increased risk of osteoporotic fractures. Currently, bisphosphonates are recommended to reduce fracture risk in these patients. The aim of this study is to evaluate the fracture risk in breast cancer patients receiving aromatase inhibitors, compared to tamoxifen users, and to assess the effectiveness of oral bisphosphonates in reducing fracture risk. We performed an observational cohort study up to 10 years of follow-up. Data were extracted from primary care records in a population database. Women diagnosed with breast cancer between 2006 and 2015 and treated with tamoxifen or aromatase inhibitors (n = 36,472) were stratified according to low (without osteoporosis diagnosis nor bisphosphonates exposure) or high (with osteoporosis and/or treated with bisphosphonates) fracture risk. Cox models were used to calculate hazard ratios (HR [95% CI]) of fracture from the propensity score-matched patients. Sensitivity analyses account for competing risk of death were performed (subdistribution hazard ratio [SHR] [95% CI]). In postmenopausal women, fracture risk in aromatase inhibitor users showed an HR 1.40 [95% CI,1.05 to 1.87] and SHR 1.48 [95% CI, 1.11 to 1.98], compared to tamoxifen. Observing aromatase inhibitors patients at high risk of fracture, bisphosphonate-treated patients had an HR 0.73 [95% CI, 0.51 to 1.04] and SHR 0.69 [95% CI, 0.48 to 0.98] compared to nontreated. In conclusion, fracture risk in postmenopausal women during aromatase inhibitor treatment, in real-life conditions, was >40% compared to tamoxifen, corroborating previous randomized controlled trials results. In high-risk patients, bisphosphonate users had lower significant fracture incidence during aromatase inhibitor therapy than nonbisphosphonate users. Monitoring fracture risk and related risk factors in aromatase inhibitor patients is advisable. © 2019 American Society for Bone and Mineral Research.

Associations Between Bone Impact Microindentation and Clinical Risk Factors for Fracture.

Impact microindentation (IMI) measures bone material strength index (BMSi) in vivo. However, clinical risk factors that affect BMSi are largely unknown. This study investigated associations between BMSi and clinical risk factors for fracture in men. BMSi was measured using the OsteoProbe in 357 men (ages 33 to 96 years) from the Geelong Osteoporosis Study. Risk factors included age, weight, height, body mass index (BMI), femoral neck bone mineral density (BMD), parental hip fracture, prior fracture, type 2 diabetes mellitus (T2DM), secondary osteoporosis, smoking, alcohol consumption, sedentary lifestyle, medications, diseases, and low serum vitamin D levels. BMSi was negatively associated with age (r = -0.131, P = 0.014), weight (r = -0.109, P = 0.040), and BMI (r = -0.083, P = 0.001); no correlations were detected with BMD (r = 0.000, P = 0.998) or height (r = 0.087, P = 0.10). Mean BMSi values for men with and without prior fracture were 80.2 ± 6.9 vs 82.8 ± 6.1 (P = 0.024); parental hip fracture, 80.1 ± 6.1 vs 82.8 ± 6.9 (P = 0.029); and T2DM, 80.3 ± 8.5 vs 82.9 ± 6.6 (P = 0.059). BMSi did not differ in the presence vs absence of other risk factors. In multivariable models, mean (± SD) BMSi remained associated with prior fracture and parental hip fracture after adjusting for age and BMI: prior fracture (80.5 ± 1.1 vs 82.8 ± 0.4, P = 0.044); parental fracture (79.9 ± 1.2 vs 82.9 ± 0.4, P = 0.015). No other confounders were identified. We conclude that in men, BMSi discriminates prior fracture and parental hip fracture, which are both known to increase the risk for incident fracture. These findings suggest that IMI may be useful for identifying men who have an increased risk for fracture.

Assessment of early therapy discontinuation and health-related quality of life in breast cancer patients treated with aromatase inhibitors: B-ABLE cohort study.

PURPOSE: The most frequent adverse effects of aromatase inhibitors (AI) are arthralgia and bone loss induction. These reduce the quality of life of patients and their adherence to the treatment. This study evaluates the early AI cessation caused by AI intolerance, and the evolution of joint pain and health-related quality of life (HRQoL) during AI treatment until 1-year after AI completion. METHODS: Data of 910 women diagnosed with early breast cancer and candidates for AI were recruited in B-ABLE cohort. AI discontinuation was analyzed by survival analysis, including Kaplan-Meier estimation and Cox regression. Patients were distributed in three groups of the study according to previous tamoxifen (TAM) exposure and length of AI treatment: TAM-2yAI, TAM-3yAI, and 5yAI. Evolution of joint pain and HRQoL in osteoporosis was evaluated using Visual Analog Scale (VAS) and ECOS-16 tests, respectively, from baseline to 1-year after AI completion through repeated-measures ANOVA. RESULTS: Risk of AI discontinuation was increased in patients previously exposed to tamoxifen compared to non-exposed (adjusted HR 5.30 [95% CI 2.23 to 12.57]). VAS and ECOS-16 scores of TAM-2yAI and TAM-3yAI groups increased during AI treatment, mainly during the first 3-12 months. After 1-year from AI completion, values tend to decrease to baseline levels. In 5yAI group, VAS and ECOS-16 levels increased at three months, and VAS remained significantly higher at 1-year post-treatment. CONCLUSIONS: AI therapy increased joint pain and reduced HRQoL, mainly during the first year of treatment. Patients previously treated with tamoxifen experienced greater pain when they switched to AI therapy and had an excess risk of discontinuation during the first 12 months. TRIAL REGISTRATION: ClinicalTrials.gov: NCT03811509. Registered 28 January 2018-Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03811509 .

Functional characterization of the C7ORF76 genomic region, a prominent GWAS signal for osteoporosis in 7q21.3.

Genome-wide association studies (GWAS) have repeatedly identified genetic variants associated with bone mineral density (BMD) and osteoporotic fracture in non-coding regions of C7ORF76, a poorly studied gene of unknown function. The aim of the present study was to elucidate the causality and molecular mechanisms underlying the association. We re-sequenced the genomic region in two extreme BMD groups from the BARCOS cohort of postmenopausal women to search for functionally relevant variants. Eight selected variants were tested for association in the complete cohort and 2 of them (rs4342521 and rs10085588) were found significantly associated with lumbar spine BMD and nominally associated with osteoporotic fracture. cis-eQTL analyses of these 2 SNPs, together with SNP rs4727338 (GWAS lead SNP in Estrada et al., Nat Genet. 44:491-501, 2012), performed in human primary osteoblasts, disclosed a statistically significant influence on the expression of the proximal neighbouring gene SLC25A13 and a tendency on the distal SHFM1. We then studied the functionality of a putative upstream regulatory element (UPE), containing rs10085588. Luciferase reporter assays showed transactivation capability with a strong allele-dependent effect. Finally, 4C-seq experiments in osteoblastic cell lines showed that the UPE interacted with different tissue-specific enhancers and a lncRNA (LOC100506136) in the region. In summary, this study is the first one to analyse in depth the functionality of C7ORF76 genomic region. We provide functional regulatory evidence for the rs10085588, which may be a causal SNP within the 7q21.3 GWAS signal for osteoporosis.

Proof of Concept on Functionality Improvement of Mesenchymal Stem-Cells, in Postmenopausal Osteoporotic Women Treated with Teriparatide (PTH1-34), After Suffering Atypical Fractures.

Osteoporosis long-term treatment with nitrogen-containing bisphosphonates, has been associated with uncommon adverse effects, as atypical femoral fractures (AFF). Thus, treatment with teriparatide (TPTD; fragment of human parathyroid hormone; PTH1-34) has been proposed for such patients. Besides its anabolizing effect on bone, TPTD may affect stem-cell mobilization and expansion. Bone marrow mononuclear cells (BMMNC) were isolated from five women that had suffered AFF associated to bisphosphonate treatment, before and after 6 months of TPTD therapy. The presence of mesenchymal stromal cells (CD73, CD90 and CD105 positive cells), gene expression of NANOG, SOX2 and OCT4, proliferation, senescence and capacity to differentiate into osteoblasts and adipocytes were analyzed. After TPTD treatment, BMMNC positive cells for CD73, CD90 and CD105 increased from 6.5 to 37.5% (p < 0.05); NANOG, SOX2 and OCT4 were upregulated, being statistically significant for NANOG (p < 0.05), and cells increased proliferative capacity more than 50% at day 7 (p < 0.05). Senescence was reduced 2.5-fold (p < 0.05), increasing differentiation capacity into osteoblasts and adipocytes, with more than twice mineralization capacity of extracellular matrix or fat-droplet formation (p < 0.05), respectively. Results show that TPTD treatment caused BMMNC "rejuvenation", increasing the number of cells in a more undifferentiated stage, with higher differentiation potency. This effect may favor TPTD anabolic action on bone in such patients with AFF, increasing osteoblast precursor cells. Such response could also arise in other osteoporotic patients treated with TPTD, without previous AFF. Furthermore, our data suggest that TPTD effect on stromal cells may have clinical implications for bone-regenerative medicine. Further studies may deepen on this potential.

Vitamin D levels in Mediterranean breast cancer patients compared with those in healthy women.

OBJECTIVES: To evaluate the vitamin D status of postmenopausal women with early estrogen-receptor-positive breast cancer and to compare it with that of healthy postmenopausal women from the same Mediterranean region. STUDY DESIGN AND OUTCOME MEASURES: Data from 691 breast cancer (BC) patients in the B-ABLE cohort were analyzed after recent cancer intervention (recent-BC) or after a minimum of two years since this intervention (long-term-BC). Patients were also stratified by previous chemotherapy exposure (ChT+ and ChT-). Plasma levels of 25-hydroxyvitamin D [25(OH)D] (25(OH)D) were compared with data from 294 healthy women (non-BC) by linear regression to estimate ß-coefficients using non-BC participants as the reference group. Age, body mass index and season of blood extraction were selected as potential confounders. RESULTS: Of the recent-BC patients, 23.7% had 25(OH)D deficiency, compared with 17.7% of the long-term-BC group, and just 1.4% of the non-BC participants. Most of the women were located in the insufficient 25(OH)D category regardless of study group. BC patients had significantly lower 25(OH)D levels than non-BC participants (adjusted ß-coefficients: -4.84 [95%CI -6.56 to -3.12] in recent-BC, and -2.05 [95%CI -4.96 to -0.14] in long-term-BC). Among BC patients, the lowest 25(OH)D levels were found in the recent-BC (ChT+) group (p < 0.001). No differences were found between the long-term-BC (ChT-), long-term-BC (ChT+) and recent-BC (ChT-) groups. Among the BC ChT+ patients, the recent-BC group had significantly lower 25(OH)D levels than the long-term-BC group (p < 0.001). CONCLUSION: Severely reduced 25(OH)D levels were detected in patients with breast cancer, particularly after recent chemotherapy. These 25(OH)D levels had partially recovered over the long term, but still remained much lower than in the healthy population.

Bone health evaluation one year after aromatase inhibitors completion.

INTRODUCTION: Breast cancer patients treated with aromatase inhibitors (AIs) experience increased bone loss during their treatment. However, there is little information about bone mineral density (BMD) after completing AI-treatment. The present study aimed to assess BMD changes one year after AI-therapy completion. METHODS: Data were collected from 864 postmenopausal women treated with AI during 5 years (5y-AI group), or during 2-3 years after taking tamoxifen therapy (pTAM-AI group). Participants with osteoporosis were treated with oral bisphosphonates (BP). BMD changes in lumbar spine (LS), femoral neck (FN) and total hip (TH) between baseline, end of treatment, and at one year post-treatment were assessed using repeated-measures ANOVA. RESULTS: At the end of AI-treatment, 382 patients had available BMD values and 316 also had post-treatment BMD values. As expected, BMD levels were decreased at AI-completion in non-BP treated patients. After one year, LS BMD increased in both groups (5y-AI: +2.11% [95%CI: 1.55 to 2.68], p < 0.001; pTAM-AI: +1.00% [95%CI: 0.49 to 1.51], p < 0.001) compared with the end of AI-therapy, while values at FN and TH remained stable. On the other hand, BMD values of BP-treated patients were increased or maintained at the end of AI-treatment and also at post-treatment. CONCLUSIONS: At one year after AI-completion, FN and TH BMD remained reduced in non-BP treated women, while LS BMD was recovered in the 5y-AI group and partially recovered in the pTAM-AI group. BP treatment increased or maintained BMD values at the end of therapy and at one year post-treatment.

In-hospital care, complications, and 4-month mortality following a hip or proximal femur fracture: the Spanish registry of osteoporotic femur fractures prospective cohort study.

We have characterised 997 hip fracture patients from a representative 45 Spanish hospitals, and followed them up prospectively for up to 4 months. Despite suboptimal surgical delays (average 59.1 hours), in-hospital mortality was lower than in Northern European cohorts. The secondary fracture prevention gap is unacceptably high at 85%. PURPOSE: To characterise inpatient care, complications, and 4-month mortality following a hip or proximal femur fracture in Spain. METHODS: Design: prospective cohort study. Consecutive sample of patients ≥ 50 years old admitted in a representative 45 hospitals for a hip or proximal femur fragility fracture, from June 2014 to June 2016 and followed up for 4 months post-fracture. Patient characteristics, site of fracture, in-patient care (including secondary fracture prevention) and complications, and 4-month mortality are described. RESULTS: A total of 997 subjects (765 women) of mean (standard deviation) age 83.6 (8.4) years were included. Previous history of fracture/s (36.9%) and falls (43%) were common, and 10-year FRAX-estimated major and hip fracture risks were 15.2% (9.0%) and 8.5% (7.6%) respectively. Inter-trochanteric (44.6%) and displaced intra-capsular (28.0%) were the most common fracture sites, and fixation with short intramedullary nail (38.6%) with spinal anaesthesia (75.5%) the most common procedures. Surgery and rehabilitation were initiated within a mean 59.1 (56.7) and 61.9 (55.1) hours respectively, and average length of stay was 11.5 (9.3) days. Antithrombotic and antibiotic prophylaxis were given to 99.8% and 98.2% respectively, whilst only 12.4% received secondary fracture prevention at discharge. Common complications included delirium (36.1 %) and kidney failure (14.1%), with in-hospital and 4-month mortality of 2.1% and 11% respectively. CONCLUSIONS: Despite suboptimal surgical delay, post-hip fracture mortality is low in Spanish hospitals. The secondary fracture prevention gap is unacceptably high at > 85%, in spite of virtually universal anti-thrombotic and antibiotic prophylaxis.

Functional Characterization of a GGPPS Variant Identified in Atypical Femoral Fracture Patients and Delineation of the Role of GGPPS in Bone-Relevant Cell Types.

Atypical femoral fractures (AFFs) are a rare but potentially devastating event, often but not always linked to bisphosphonate (BP) therapy. The pathogenic mechanisms underlying AFFs remain obscure, and there are no tests available that might assist in identifying those at high risk of AFF. We previously used exome sequencing to explore the genetic background of three sisters with AFFs and three additional unrelated AFF cases, all previously treated with BPs. We detected 37 rare mutations (in 34 genes) shared by the three sisters. Notably, we found a p.Asp188Tyr mutation in the enzyme geranylgeranyl pyrophosphate synthase, a component of the mevalonate pathway, which is critical to osteoclast function and is inhibited by N-BPs. In addition, the CYP1A1 gene, responsible for the hydroxylation of 17ß-estradiol, estrone, and vitamin D, was also mutated in all three sisters and one unrelated patient. Here we present a detailed list of the variants found and report functional analyses of the GGPS1 p.Asp188Tyr mutation, which showed a severe reduction in enzyme activity together with oligomerization defects. Unlike BP treatment, this genetic mutation will affect all cells in the carriers. RNAi knockdown of GGPS1 in osteoblasts produced a strong mineralization reduction and a reduced expression of osteocalcin, osterix, and RANKL, whereas in osteoclasts, it led to a lower resorption activity. Taken together, the impact of the mutated GGPPS and the relevance of the downstream effects in bone cells make it a strong candidate for AFF susceptibility. We speculate that other genes such as CYP1A1 might be involved in AFF pathogenesis, which remains to be functionally proved. The identification of the genetic background for AFFs provides new insights for future development of novel risk assessment tools. © 2018 American Society for Bone and Mineral Research.

Common and rare variants of WNT16, DKK1 and SOST and their relationship with bone mineral density.

Numerous GWAS and candidate gene studies have highlighted the role of the Wnt pathway in bone biology. Our objective has been to study in detail the allelic architecture of three Wnt pathway genes: WNT16, DKK1 and SOST, in the context of osteoporosis. We have resequenced the coding and some regulatory regions of these three genes in two groups with extreme bone mineral density (BMD) (n = ∼50, each) from the BARCOS cohort. No interesting novel variants were identified. Thirteen predicted functional variants have been genotyped in the full cohort (n = 1490), and for ten of them (with MAF > 0.01), the association with BMD has been studied. We have found six variants nominally associated with BMD, of which 2 WNT16 variants predicted to be eQTLs for FAM3C (rs55710688, in the Kozak sequence and rs142005327, within a putative enhancer) withstood multiple-testing correction. In addition, two rare variants in functional regions (rs190011371 in WNT16b 3'UTR and rs570754792 in the SOST TATA box) were found only present in three women each, all with BMD below the mean of the cohort. Our results reinforce the higher importance of regulatory versus coding variants in these Wnt pathway genes and open new ways for functional studies of the relevant variants.

Advances in the evaluation of bone health in kidney transplant patients. / Avances en la valoración de la salud ósea en el trasplantado renal.

Bone disease related to chronic kidney disease and, particularly, to kidney transplant patients is a common cause or morbidity and mortality, especially due to a higher risk of osteoporotic fractures. Despite the fact that this has been known for decades, to date, an appropriate diagnostic strategy has yet to be established. Apart from bone biopsy, which is invasive and scarcely used, no other technique is available to accurately establish the risk of fracture in kidney patients. Techniques applied to the general population, such as bone densitometry, have not been subjected to sufficient external validation and their use is not systematic. This means that the identification of patients at risk of fracture and therefore those who are candidates for preventive strategies is an unmet need. Bone strength, defined as the ability of the bone to resist fracture, is determined by bone mineral density (measured by bone densitometry), trabecular architecture and bone tissue quality. The trabecular bone score estimates bone microarchitecture, and low values have been described as an independent predictor of increased fracture risk. Bone microindentation is a minimally invasive technique that measures resistance of the bone to micro-cracks (microscopic separation of mineralised collagen fibres), and therefore bone tissue biomechanical properties. The superiority over bone densitometry of the correlation between the parameters measured by trabecular bone score and microindentation with the risk of fracture in diverse populations led us to test its feasibility in chronic kidney disease and kidney transplant patients.

Octodon degus, a new model to study the agonist and plexus-induced response in the urinary bladder.

Urinary bladder function consists in the storage and controlled voiding of urine. Translational studies require animal models that match human characteristics, such as Octodon degus, a diurnal rodent. This study aims to characterize the contractility of the detrusor muscle and the morphology and code of the vesical plexus from O. degus. Body temperature was measured by an intra-abdominal sensor, the contractility of detrusor strips was evaluated by isometric tension recording, and the vesical plexus was studied by electrical field stimulation (EFS) and immunofluorescence. The animals showed a diurnal chronotype as judged from core temperature. The myogenic contractile response of the detrusor muscle to increasing doses of KCl reached its maximum (31.04 mN/mm2) at 60 mM. In the case of cumulative dose-response of bethanecol, the maximum response (37.42 mN/mm2) was reached at 3.2 × 10-4 M. The response to ATP was clearly smaller (3.8 mN/mm2). The pharmacological dissection of the EFS-induced contraction identified ACh and sensory fibers as the main contributors to this response. The neurons of the vesical plexus were located mainly in the trigone area, grouped in big and small ganglia. Out of them, 48.1 % of the neurons were nitrergic and 62.7 % cholinergic. Our results show functional and morphological similarities between the urinary bladder of O. degus and that of humans.

AI-related BMD variation in actual practice conditions: A prospective cohort study.

The aim of the study was to evaluate the progression of bone mineral density (BMD) during 3 years of aromatase inhibitors (AI) therapy in actual practice conditions. This prospective, clinical cohort study of Barcelona-Aromatase induced Bone Loss in Early breast cancer (B-ABLE) assessed BMD changes during 3 years of AI treatment in women with breast cancer. Patients with osteoporosis (T score < -2.5 or T score ≤ -2.0) and a major risk factor and/or prevalent fragility fractures were treated with oral bisphosphonates (BPs). Of 685 women recruited, 179 (26.1%) received BP treatment. By the third year of AI therapy, this group exhibited increased BMD in the lumbar spine (LS; 2.59%) and femoral neck (FN; 2.50%), although the increase was significant only within the first year (LS: 1.99% and FN: 2.04%). Despite BP therapy, however, approximately 15% of these patients lost more than 3% of their baseline bone mass. At 3 years, patients without BP experienced BMD decreases in the LS (-3.10%) and FN (-2.79%). In this group, BMD changes occurred during the first (LS: -1.33% and FN: -1.25%), second (LS: -1.19% and FN: -0.82%), and third (LS: -0.57% and FN: -0.65%) years of AI treatment. Increased BMD (>3%) was observed in just 7.6% and 10.8% of these patients at the LS and FN, respectively. Our data confirm a clinically relevant bone loss associated with AI therapy amongst nonusers of preventative BPs. We further report on the importance of BMD monitoring as well as calcium and 25-hydroxy vitamin D supplementation in these patients.

Parathyroid Hormone-Related Protein Analogs as Osteoporosis Therapies.

The only bone anabolic agent currently available for osteoporosis treatment is parathyroid hormone (PTH)-either its N-terminal 1-34 fragment or the whole molecule of 1-84 aminoacids-whose intermittent administration stimulates new bone formation by targeting osteoblastogenesis and osteoblast survival. PTH-related protein (PTHrP) is an abundant factor in bone which shows N-terminal homology with PTH and thus exhibits high affinity for the same PTH type 1 receptor in osteoblasts. Therefore, it is not surprising that intermittently administered N-terminal PTHrP peptides induce bone anabolism in animals and humans. Furthermore, the C-terminal region of PTHrP also elicits osteogenic features in vitro in osteoblastic cells and in various animal models of osteoporosis. In this review, we discuss the current concepts about the cellular and molecular mechanisms whereby PTHrP may induce anabolic actions in bone. Pre-clinical studies and clinical data using N-terminal PTHrP analogs are also summarized, pointing to PTHrP as a promising alternative to current bone anabolic therapies.