HIV infection is associated with upregulated circulating levels of the inflammaging miR-21-5p

BACKGROUND

HIV infection produces a chronic inflammation which leads to early aging of people living with HIV. Even though antiretroviral treatments (ART) have significantly increased HIV patient survival, an underlying chronic inflammation persists leading to HIV-related comorbidities. In this context, changes in microRNAs (miRNAs) expression may contribute to this inflammatory response. This study aims to detect differential expression of circulating miRNAs in treatment-naïve HIV-infected individuals compared to uninfected controls and evaluation of altered miRNAs after one year of ART.

METHODS

Serum from patients and controls was collected at baseline and after 48-weeks on ART in HIV-treated patients. Circulating miRNAs were analysed using next generation sequencing.

RESULTS

A total of 32 HIV patients and 10 controls were recruited. Of HIV+ individuals, 7 were long-term non-progressors (elite controllers), a group of HIV-infected individuals that spontaneously control the infection. Higher circulating levels of miR-21-5p, and lower levels of miR-6503-3p and miR-3135b were detected in HIV+ progressors. After one year of ART, these miRNAs remain altered. Moreover, miR-21-5p and miR-6503-3p were also altered in elite controllers compared to control group. In silico analyses showed that miR-21-5p target pathways are related to inflammation mechanisms and immune system.

CONCLUSION

miR-21-5p circulating levels are involved in inflammation and oxidative stress mechanisms in HIV patients even after one year of ART or in elite controllers.

Effect of Heat Treatment on Osteoblast Performance and Bactericidal Behavior of Ti6Al4V(ELI)-3at.%Cu Fabricated by Laser Powder Bed Fusion

Cu addition to alloys for biomedical applications has been of great interest to reduce bacterial growth. In situ-alloyed Ti6Al4V(ELI)-3at.%Cu was successfully manufactured by laser powder bed fusion (L-PBF). Even so, post-heat treatments are required to avoid distortions and/or achieve required/desired mechanical and fatigue properties. The present study is focused on the investigation of microstructural changes in L-PBF Ti6Al4V(ELI)-3at.%Cu after stress relieving and annealing treatments, as well as their influence on osteoblast and bactericidal behavior. After the stress relieving treatment, a homogenously distributed β phase and CuTi₂ intermetallic precipitates were observed over the α' matrix. The annealing treatment led to the increase in amount and size of both types of precipitates, but also to phase redistribution along α lamellas. Although microstructural changes were not statistically significant, such increase in β and CuTi₂ content resulted in an increase in osteoblast proliferation after 14 days of cell culture. A significant bactericidal behavior of L-PBF Ti6Al4V(ELI)-3at.%Cu by means of ion release was found after the annealing treatment, provably due to the easier release of Cu ions from β phase. Biofilm formation was inhibited in all on Cu-alloyed specimens with stress relieving but also annealing treatment.

Changes in bone quality after switching from a TDF to a TAF based ART: A pilot randomized study

BACKGROUND

The impact of tenofovir disoproxil fumarate (TDF) antiretroviral (ART) regimens on bone health has been characterized mostly by bone mineral density (BMD), but recently also by bone quality (BQ). The aim of this pilot study is to assess the changes in BMD and BQ after switch from TDF to tenofovir alafenamide (TAF) ART.

METHODS

HIV individuals receiving TDF-based ART were randomized to switch to Bictegravir-TAF-Emtricitabine or to remain in the same regimen. At baseline and 24-weeks after randomization, participants underwent bone mineral density (BMD) by DXA and BQ assessment using bone microindentation, a validated technique that measures bone tissue quality expressed as bone material strength index (BMSi). A panel of plasma bone turnover biomarkers were measured by ELISA at the same time-points. Values are expressed as median [interquartile range] and non-parametric tests were used where appropriate.

RESULTS

A total of 24 HIV individuals were included in the study, 19 of which were men (80%). Median age at baseline was 43 years (IQR 38-54). Half of individuals were allocated in the TDF group while the other half changed to TAF treatment. No differences at baseline between both groups were detected in any parameter. Non-significant changes nor in lumbar or femoral BMD at week 24 was found in any regimen. In contrast, there was an increase in BMSi in the TAF arm at 24 weeks, and thus an improvement in BQ[81.6 (79-83) to 86 (80-88) (+5.1%);p=0.041], whereas the TDF arm remained stable from 82 (76-85) at baseline to 82 (73-83);p=0.812. Hence, at week 24 there were significant differences in BQ between arms (p=0.049). A reduction in bone formation markers was found at week 24 in both regimens: N-terminal propeptide of type-1 collagen decreased a 20% (-35 - -0.6); p=0.031 with TAF and -16% (-25 - -5); p=0.032 with TDF. Also a decrease in bone resorption marker C-telopeptide with TAF was detected [-10% (-19 - -5);p=0.028] but not with TDF (p=0.232), suggesting a less metabolically active bone after switching to TAF.

CONCLUSION

A bone quality improvement was found after switching from a TDF to a TAF based ART independently of BMD, suggesting that the bone health benefits of TAF may extend beyond BMD. Future research should be directed to confirm these findings and to identify the underlying mechanisms of ART related bone toxicity.

Anti-SARS-COV-2 specific immunity in HIV immunological non-responders after mRNA-based COVID-19 vaccination

Individuals infected with the human immunodeficiency virus type 1 (HIV-1) belong to the group of people most vulnerable to SARS-CoV-2 infections and the associated disease COVID-19. Here we describe SARS-CoV-2-specific antibody and cellular immune responses in a small cohort of immunological non-responder HIV-1 patients (HIV-INRs) after receiving the COVID-19 mRNA-based BioNTech/Pfizer vaccine. Compared to the control group of vaccinated healthy individuals that all developed a virus-specific immune response, 5 of 10 vaccinated HIV-1 patients showed insufficient immune responses. The lack of response was not directly correlated with patients CD4 cell counts. Three of the five non-responders that agreed to receive a booster vaccination subsequently generated a virus-specific response. Thus, even HIV-INRs can be efficiently vaccinated against COVID-19 but may require a follow-up by virus-specific immune monitoring to guarantee clinical vaccine benefits.

Clinical description and genetic analysis of a novel familial skeletal dysplasia characterized by high bone mass and lucent bone lesions

High bone mass (HBM) disorders are a clinically and genetically heterogeneous subgroup of rare skeletal dysplasias. Here we present a case of a previously unreported familial skeletal dysplasia characterized by HBM and lucent bone lesions that we aimed to clinically characterize and genetically investigate. For phenotyping, we reviewed past clinical records and imaging tests, and performed physical examination (PE), bone densitometry, and mineral panels in affected individuals, including a male proband, his son and daughter, in addition to unaffected controls, including the proband's wife and brother. Affected individuals also underwent impact microindentation (IMI). In an effort to elucidate the disorder's molecular etiology, whole exome sequencing (WES) was performed in all individuals to filter for rare variants present only in affected ones. The cases displayed a unique skeletal phenotype with a mix of sclerotic features and lucent bone lesions, and high IMI values. Bone mineral density was very elevated in the proband and his daughter. The proband's daughter also exhibited idiopathic scoliosis (IS), in addition to mild thrombocytopenia and mild structural thyroid abnormalities, which were the only extra-skeletal abnormalities identified. WES analysis yielded 5 rare putative pathogenic variants in affected members in genes that are associated with bone metabolism including: SEM4AD, TBX18, PTCH1, PTK7, and ADGRE5. The PTK7 variant appeared as possibly implicated in the development of IS while the TBX18 and SEMA4D variants stood out as the strongest candidates for the lucent bone lesions and HBM, respectively, given their high predicted pathogenicity and putative role in bone biology. Variant functionality should be addressed in the future to assess their implication in skeletal metabolism as it is the first time that mutations in TBX18 and SEMA4D have been associated to bone developmental lesions and mineral metabolism in a clinical setting.

Gene Network of Susceptibility to Atypical Femoral Fractures Related to Bisphosphonate Treatment

Atypical femoral fractures (AFF) are rare fragility fractures in the subtrocantheric or diaphysis femoral region associated with long-term bisphosphonate (BP) treatment. The etiology of AFF is still unclear even though a genetic basis is suggested. We performed whole exome sequencing (WES) analysis of 12 patients receiving BPs for at least 5 years who sustained AFFs and 4 controls, also long-term treated with BPs but without any fracture. After filtration and prioritization of rare variants predicted to be damaging and present in genes shared among at least two patients, a total of 272 variants in 132 genes were identified. Twelve of these genes were known to be involved in bone metabolism and/or AFF, highlighting DAAM2 and LRP5, both involved in the Wnt pathway, as the most representative. Afterwards, we intersected all mutated genes with a list of 34 genes obtained from a previous study of three sisters with BP-related AFF, identifying nine genes. One of these (MEX3D) harbored damaging variants in two AFF patients from the present study and one shared among the three sisters. Gene interaction analysis using the AFFNET web suggested a complex network among bone-related genes as well as with other mutated genes. BinGO biological function analysis highlighted cytoskeleton and cilium organization. In conclusion, several genes and their interactions could provide genetic susceptibility to AFF, that along with BPs treatment and in some cases with glucocorticoids may trigger this so feared complication.

In Vitro Characterization of In Situ Alloyed Ti6Al4V(ELI)-3 at.% Cu Obtained by Laser Powder Bed Fusion

The intensive cytotoxicity of pure copper is effectively kills bacteria, but it can compromise cellular behavior, so a rational balance must be found for Cu-loaded implants. In the present study, the individual and combined effect of surface composition and roughness on osteoblast cell behavior of in situ alloyed Ti6Al4V(ELI)-3 at.% Cu obtained by laser powder bed fusion was studied. Surface composition was studied using scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. Surface roughness measurements were carried out using confocal microscopy. In vitro osteoblast performance was evaluated by means of cell morphology observation of cell viability, proliferation, and mineralization. In vitro studies were performed at 1, 7, and 14 days of cell culture, except for cell mineralization at 28 days, on grounded and as-built (rough) samples with and without 3 at.% Cu. The addition of 3 at.% Cu did not show cell cytotoxicity but inhibited cell proliferation. Cell mineralization tends to be higher for samples with 3 at.% Cu content. Surface roughness inhibited cell proliferation too, but showed enhanced cell mineralization capacity and therefore, higher osteoblast performance, especially when as-built samples contained 3 at.% Cu. Cell proliferation was only observed on ground samples without Cu but showed the lowest cell mineralization.

Calcifediol Treatment and COVID-19-Related Outcomes

CONTEXT

COVID-19 is a major health problem because of saturation of intensive care units (ICU) and mortality. Vitamin D has emerged as a potential treatment able to reduce the disease severity.

OBJECTIVE

This work aims to elucidate the effect of 25(OH)D3 (calcifediol) treatment on COVID-19-related outcomes.

METHODS

This observational cohort study was conducted from March to May 2020, among patients admitted to COVID-19 wards of Hospital del Mar, Barcelona, Spain. A total of 930 patients with COVID-19 were included; 92 were excluded because of previous calcifediol intake. Of the remaining 838, a total of 447 received calcifediol (532 μg on day 1 plus 266 μg on days 3, 7, 15, and 30), whereas 391 were not treated at the time of hospital admission (intention-to-treat). Of the latter, 53 patients were treated later during ICU admission and were allocated in the treated group in a second analysis. In healthy individuals, calcifediol is about 3.2-fold more potent on a weight basis than cholecalciferol. Main outcome measures were ICU admission and mortality.

RESULTS

ICU assistance was required by 102 (12.2%) participants. Out of 447 patients treated with calcifediol at admission, 20 (4.5%) required the ICU, compared to 82 (21%) out of 391 nontreated (P < .001). Logistic regression of calcifediol treatment on ICU admission, adjusted by age, sex, linearized 25-hydroxyvitamin D levels at baseline, and comorbidities showed that treated patients had a reduced risk of requiring the ICU (odds ratio [OR] 0.13; 95% CI 0.07-0.23). Overall mortality was 10%. In the intention-to-treat analysis, 21 (4.7%) out of 447 patients treated with calcifediol at admission died compared to 62 patients (15.9%) out of 391 nontreated (P = .001). Adjusted results showed a reduced mortality risk with an OR of 0.21 (95% CI, 0.10-0.43). In the second analysis, the obtained OR was 0.52 (95% CI, 0.27-0.99).

CONCLUSION

In patients hospitalized with COVID-19, calcifediol treatment significantly reduced ICU admission and mortality.

A Roadmap to Gene Discoveries and Novel Therapies in Monogenic Low and High Bone Mass Disorders

Genetic disorders of the skeleton encompass a diverse group of bone diseases differing in clinical characteristics, severity, incidence and molecular etiology. Of particular interest are the monogenic rare bone mass disorders, with the underlying genetic defect contributing to either low or high bone mass phenotype. Extensive, deep phenotyping coupled with high-throughput, cost-effective genotyping is crucial in the characterization and diagnosis of affected individuals. Massive parallel sequencing efforts have been instrumental in the discovery of novel causal genes that merit functional validation using in vitro and ex vivo cell-based techniques, and in vivo models, mainly mice and zebrafish. These translational models also serve as an excellent platform for therapeutic discovery, bridging the gap between basic science research and the clinic. Altogether, genetic studies of monogenic rare bone mass disorders have broadened our knowledge on molecular signaling pathways coordinating bone development and metabolism, disease inheritance patterns, development of new and improved bone biomarkers, and identification of novel drug targets. In this comprehensive review we describe approaches to further enhance the innovative processes taking discoveries from clinic to bench, and then back to clinic in rare bone mass disorders. We highlight the importance of cross laboratory collaboration to perform functional validation in multiple model systems after identification of a novel disease gene. We describe the monogenic forms of rare low and high rare bone mass disorders known to date, provide a roadmap to unravel the genetic determinants of monogenic rare bone mass disorders using proper phenotyping and genotyping methods, and describe different genetic validation approaches paving the way for future treatments.

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.

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.

In-vitro comparison of hydroxyapatite coatings obtained by cold spray and conventional thermal spray technologies

Hydroxyapatite (HA) coatings onto Ti6Al4V alloy substrates were obtained by several thermal spray technologies: atmospheric plasma spray (APS) and high velocity oxy fuel (HVOF), together with the cold spray (CS) technique. A characterization study has been performed by means of surface and microstructure analyses, as well as biological performance. In-vitro tests were performed with primary human osteoblasts at 1, 7 and 14 days of cell culture on substrates. Cell viability was tested by MTS and LIVE/DEAD assays, cell differentiation by alkaline phosphatase (ALP) quantification, and cell morphology was analyzed by scanning electron microscopy. The HA coatings showed an increase of HA crystallinity from 62,4% to 89%, but also an increase of hydrophilicity from ∼32° to 0°, with the decrease of the operating temperature of the thermal spray techniques (APS > HVOF > CS). Additionally, APS HA coatings showed more surface micro-features than HVOF and CS HA coatings; cells onto APS HA coatings showed faster attachment by acquiring osteoblastic morphology in comparison with the rounded cell morphology observed onto CS HA coatings at 1 day of cell culture. HVOF HA coatings also showed proper cell adherence but did not show extended filopodia as cells onto APS HA coatings. However, at 14 days of cell culture, higher cell proliferation and differentiation was detected on HA coatings with higher crystallinity (HVOF and CS techniques). Cell attachment is suggested to be favoured by surface micro-features but also moderate surface wettability whereas cell proliferation and differentiation is suggested to be highly influenced by HA crystallinity and crystal size.

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.

Pro-osteoporotic miR-320a impairs osteoblast function and induces oxidative stress

MicroRNAs (miRNAs) are important regulators of many cellular processes, including the differentiation and activity of osteoblasts, and therefore, of bone turnover. MiR-320a is overexpressed in osteoporotic bone tissue but its role in osteoblast function is unknown. In the present study, functional assays were performed with the aim to elucidate the mechanism of miR-320a action in osteoblastic cells. MiR-320a was either overexpressed or inhibited in human primary osteoblasts (hOB) and gene expression changes were evaluated through microarray analysis. In addition, the effect of miR-320a on cell proliferation, viability, and oxidative stress in hOB was evaluated. Finally, matrix mineralization and alkaline phosphatase activity were assessed in order to evaluate osteoblast functionality. Microarray results showed miR-320a regulation of a number of key osteoblast genes and of genes involved in oxidative stress. Regulation of osteoblast differentiation and ossification appeared as the best significant biological processes (PANTHER P value = 3.74E-05; and P value = 3.06E-04, respectively). The other enriched pathway was that of the cellular response to cadmium and zinc ions, mostly by the overexpression of metallothioneins. In hOBs, overexpression of miR-320a increased cell proliferation and oxidative stress levels whereas mineralization capacity was reduced. In conclusion, overexpression of miR-320a increased stress oxidation levels and was associated with reduced osteoblast differentiation and functionality, which could trigger an osteoporotic phenotype.

In-vitro study of hierarchical structures: Anodic oxidation and alkaline treatments onto highly rough titanium cold gas spray coatings for biomedical applications

Hierarchical structures were obtained applying two different nanotexturing surface treatments onto highly rough commercial pure titanium coatings by cold spray: (i) anodic oxidation and (ii) alkaline treatments. An extended surface characterization in terms of topography, composition, and wettability has been performed to understand how those parameters affect to cell response. Primary human osteoblasts extracted from knee were seeded onto the as-sprayed titanium surface before and after the nanotexturing treatments. Cell viability was tested by using MTS and LIVE/DEAD assays, as well as osteoblasts differentiation by alkaline phosphatase (ALP) quantification at 3 and 10 days of cell culture. The combination of micro-/nano-roughness results in a significantly increase of cell proliferation, as well as cell differentiation after 10 days of cell culture in comparison with the non-treated coatings.

Osteoblastic cell response on high-rough titanium coatings by cold spray

Highly rough and porous commercially pure titanium coatings have been directly produced for first time by the cold spray technology, which is a promising technology in front of the vacuum plasma spray for oxygen sensitive materials. The wettability properties as well as the biocompatibility evaluation have been compared to a simply sand blasted Ti6Al4V alloy substrate. Surface topographies were analysed using confocal microscopy. Next, osteoblast morphology (Phalloidin staining), proliferation (MTS assay), and differentiation (alkaline phosphatase activity) were examined along 1, 7 and 14 days of cell culture on the different surfaces. Finally, mineralization by alizarin red staining was quantified at 28 days of cell culture. The contact angle values showed an increased hydrophilic behaviour on the as-sprayed surface with a good correlation to the biological response. A higher cell viability, proliferation and differentiation were obtained for highly rough commercial pure titanium coatings in comparison with sand blasted substrates. Cell morphology was similar in all coatings tested; at 14 days both samples showed extended filopodia. A higher amount of calcium-rich deposits was detected on highly rough surfaces. In summary, in-vitro results showed an increase of biological properties when surface roughness increases.

Fracture during oral bisphosphonate therapy is associated with deteriorated bone material strength index

BACKGROUND

Some patients experience fractures while receiving oral bisphosphonates (BPs) treatment. Clinical risk factors, advanced bone density loss, and microarchitecture deterioration have been associated with such fractures but bone tissue properties other than bone mineral density (BMD) have not been assessed.

METHODS

In a cross-sectional study of postmenopausal women on bisphosphonates for at least 4years with good adherence to treatment, 21 patients with incident fractures were compared with 18 treated patients without new fractures. Demographic and clinical variables, BMD, laboratory tests, and bone material strength index (BMSi) assessed by impact microindentation at the tibial diaphysis were recorded for all participants.

RESULTS

Clinical and laboratory results did not differ between patients taking BPs with incident fractures and those without new fractures. However, BMSi was significantly lower (mean±SD) in those who fractured (73.76±6.49) than in no-fracture patients (81.64±6.26; p=0.001). Lumbar spine (LS) BMD was also lower in fractured patients (p=0.03). Adjusted models including age, body mass index, years on BP treatment, and LS-BMD confirmed an increase in fracture risk per BMSi standard deviation decrease: adjusted OR 23.5 [95% CI 2.16 to 255.66], p=0.01. ROC analyses showed an area under the curve of 0.82 (95% CI 0.68 to 0.95) for BMSi, higher than that for BMD at any location, which ranged from 0.64 (95% CI 0.47 to 0.82) for femoral neck (FN) BMD to 0.71 (95% CI 0.55 to 0.87) for LS-BMD.

CONCLUSIONS

Patients who fracture while receiving BPs treatment have worse BMSi scores than BP-treated patients without fractures. The potential for BMSi to provide an additional osteoporosis treatment target should be explored.

Expression profiling of microRNAs in human bone tissue from postmenopausal women

Bone tissue is composed of several cell types, which express their own microRNAs (miRNAs) that will play a role in cell function. The set of total miRNAs expressed in all cell types configures the specific signature of the bone tissue in one physiological condition. The aim of this study was to explore the miRNA expression profile of bone tissue from postmenopausal women. Tissue was obtained from trabecular bone and was analyzed in fresh conditions (n = 6). Primary osteoblasts were also obtained from trabecular bone (n = 4) and human osteoclasts were obtained from monocyte precursors after in vitro differentiation (n = 5). MicroRNA expression profiling was obtained for each sample by microarray and a global miRNA analysis was performed combining the data acquired in all the microarray experiments. From the 641 miRNAs detected in bone tissue samples, 346 (54%) were present in osteoblasts and/or osteoclasts. The other 46% were not identified in any of the bone cells analyzed. Intersection of osteoblast and osteoclast arrays identified 101 miRNAs shared by both cell types, which accounts for 30-40% of miRNAs detected in these cells. In osteoblasts, 266 miRNAs were detected, of which 243 (91%) were also present in the total bone array, representing 38% of all bone miRNAs. In osteoclasts, 340 miRNAs were detected, of which 196 (58%) were also present in the bone tissue array, representing 31% of all miRNAs detected in total bone. These analyses provide an overview of miRNAs expressed in bone tissue, broadening our knowledge in the microRNA field.

Real-Time Protein and Cell Binding Measurements on Hydroxyapatite Coatings

Although a lot of in vitro and in vivo assays have been performed during the last few decades years for hydroxyapatite bioactive coatings, there is a lack of exploitation of real-time in vitro interaction measurements. In the present work, real-time interactions for a plasma sprayed hydroxyapatite coating were measured by a Multi-Parametric Surface Plasmon Resonance (MP-SPR), and the results were compared with standard traditional cell viability in vitro assays. MP-SPR is proven to be suitable not only for measurement of molecule-molecule interactions but also molecule-material interaction measurements and cell interaction. Although SPR is extensively utilized in interaction studies, recent research of protein or cell adsorption on hydroxyapatite coatings for prostheses applications was not found. The as-sprayed hydroxyapatite coating resulted in 62.4% of crystalline phase and an average thickness of 24 ± 6 μm. The MP-SPR was used to measure lysozyme protein and human mesenchymal stem cells interaction to the hydroxyapatite coating. A comparison between the standard gold sensor and Hydroxyapatite (HA)-plasma coated sensor denoted a clearly favourable cell attachment on HA coated sensor as a significantly higher signal of cell binding was detected. Moreover, traditional cell viability and proliferation tests showed increased activity with culture time indicating that cells were proliferating on HA coating. Cells show homogeneous distribution and proliferation along the HA surface between one and seven days with no significant mortality. Cells were flattened and spread on rough surfaces from the first day, with increasing cytoplasmatic extensions during the culture time.

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.

Whole-genome sequencing identifies EN1 as a determinant of bone density and fracture

The extent to which low-frequency (minor allele frequency (MAF) between 1-5%) and rare (MAF ≤ 1%) variants contribute to complex traits and disease in the general population is mainly unknown. Bone mineral density (BMD) is highly heritable, a major predictor of osteoporotic fractures, and has been previously associated with common genetic variants, as well as rare, population-specific, coding variants. Here we identify novel non-coding genetic variants with large effects on BMD (ntotal = 53,236) and fracture (ntotal = 508,253) in individuals of European ancestry from the general population. Associations for BMD were derived from whole-genome sequencing (n = 2,882 from UK10K (ref. 10); a population-based genome sequencing consortium), whole-exome sequencing (n = 3,549), deep imputation of genotyped samples using a combined UK10K/1000 Genomes reference panel (n = 26,534), and de novo replication genotyping (n = 20,271). We identified a low-frequency non-coding variant near a novel locus, EN1, with an effect size fourfold larger than the mean of previously reported common variants for lumbar spine BMD (rs11692564(T), MAF = 1.6%, replication effect size = +0.20 s.d., Pmeta = 2 × 10(-14)), which was also associated with a decreased risk of fracture (odds ratio = 0.85; P = 2 × 10(-11); ncases = 98,742 and ncontrols = 409,511). Using an En1(cre/flox) mouse model, we observed that conditional loss of En1 results in low bone mass, probably as a consequence of high bone turnover. We also identified a novel low-frequency non-coding variant with large effects on BMD near WNT16 (rs148771817(T), MAF = 1.2%, replication effect size = +0.41 s.d., Pmeta = 1 × 10(-11)). In general, there was an excess of association signals arising from deleterious coding and conserved non-coding variants. These findings provide evidence that low-frequency non-coding variants have large effects on BMD and fracture, thereby providing rationale for whole-genome sequencing and improved imputation reference panels to study the genetic architecture of complex traits and disease in the general population.

Skeletal adverse effects with aromatase inhibitors in early breast cancer: evidence to date and clinical guidance

Aromatase inhibitors (AIs) are routinely used in the adjuvant treatment of women with hormone receptor-positive early breast cancer. Patients who receive AIs have an increased risk of bone loss and arthralgia compared with those treated with tamoxifen. In addition to the effects of AIs, the population of women with early breast cancer has a high prevalence of 25-hydroxyvitamin D (25(OH)D) insufficiency. In our experience 88% of patients had concentrations lower than 30 ng/ml. Vitamin D supplementation should be adapted to the baseline concentration. Another relevant finding in our research program was the close relationship between 25(OH)D levels and intensity of AI-related arthralgia (AIrA). A target concentration of 40 ng/ml 25(OH)D may prevent development of AIrA. We also demonstrate that AIrA is genetically determined: single nucleotide polymorphisms located in genes encoding key factors for the metabolism of estrogens and vitamin D (CYP17A1, VDR, and CYP27B1) are associated with self-reported arthralgia during AI therapy. We recommend establishing an individualized protocol of bone-health surveillance based on baseline and evolutionary clinical variables.

In vitro performance of ceramic coatings obtained by high velocity oxy-fuel spray

Hydroxyapatite coatings obtained by plasma-spraying have been used for many years to improve biological performance of bone implants, but several studies have drawn attention to the problems arising from high temperatures and the lack of mechanical properties. In this study, plasma-spraying is substituted by high velocity oxy-fuel (HVOF) spray, with lower temperatures reached, and TiO2 is added in low amounts to hydroxyapatite in order to improve the mechanical properties. Four conditions have been tested to evaluate which are those with better biological properties. Viability and proliferation tests, as well as differentiation assays and morphology observation, are performed with human osteoblast cultures onto the studied coatings. The hydroxyapatite-TiO2 coatings maintain good cell viability and proliferation, especially the cases with higher amorphous phase amount and specific surface, and promote excellent differentiation, with a higher ALP amount for these cases than for polystyrene controls. Observation by SEM corroborates this excellent behaviour. In conclusion, these coatings are a good alternative to those used industrially, and an interesting issue would be improving biological behaviour of the worst cases, which in turn show the better mechanical properties.

Analyses of RANK and RANKL in the post-GWAS context: functional evidence of vitamin D stimulation through a RANKL distal region

Over the past decade, many genome-wide association studies (GWAs) and meta-analyses have identified genes and regions involved in osteoporotic phenotypes. Nevertheless, the large majority of these results were not tested at any functional level. GWA-associated single-nucleotide polymorphisms (SNPs) near candidate genes such as RANK and RANKL suggest that these SNPs and/or other variants nearby may be involved in bone phenotype determination. This study focuses on SNPs along these two genes, which encode proteins with a well-established role in the bone remodeling equilibrium. Thirty-three SNPs, chosen for their location in evolutionary conserved regions or replicated from previous studies, were genotyped in the BARCOS cohort of 1061 postmenopausal women and tested for association with osteoporotic phenotypes. SNP rs9594738, which lies 184 kb upstream of the RANKL gene, was the only SNP found to be associated with a bone phenotype (dominant model: beta coefficient = -0.034, p = 1.5 × 10(-4) , for lumbar spine bone mineral density). Functional experiments exploring a distal region (DR) of 831 bp that harbors this SNP in a centered position (nt 470) demonstrated its capacity to inhibit the RANKL promoter in reporter gene assays. Remarkably, this DR inhibition was significantly reduced in the presence of vitamin D. In conclusion, the GWA-associated SNP rs9594738 lies in a region involved in transcription regulation through which vitamin D could be regulating RANKL expression and bone mineral density.

Host serum is not indispensable in collagen performance in viable meniscal transplantation at 4-week incubation

PURPOSE

Viable meniscal transplantation has been criticized as an expensive and logistically demanding technique. The purpose was to compare the standard culture medium with another culture medium that is more widely available and easier to work with and to assess the collagen net ultrastructure architecture and the capacity of the preserved cells to produce proteins.

METHODS

Ten fresh lateral menisci were harvested. Each meniscus was divided into three parts; control group, fetal-bovinum-serum group and Insulin-Transferrin-Selenium group during 4 weeks. Cell metabolism was assessed with the gene expression of type I collagen, type II collagen and aggrecan. Collagen ultrastructure was assessed with transmission electron microscopy. The Collagen Meniscal Architecture scoring system was used to evaluate the degree of meniscal disarray.

RESULTS

Type I collagen was expressed more in the fetal-bovinum-serum group than in the ITS group (P = 0.036). No differences were found between cultured samples and control groups. Type II collagen showed decreased expression in both cultured groups compared with the control group. No differences were observed in the gene expression of aggrecan in either group. No differences were observed when the Collagen Meniscal Architecture scoring system was applied.

CONCLUSIONS

Insulin-Transferrin-Selenium-supplemented medium is at least as effective as the fetal-bovinum-serum-supplemented medium to preserve the net architecture of the meniscal tissue. Gene expression of the studied proteins was similar in the Insulin-Transferrin-Selenium group to that observed in the control group at 4 weeks. Insulin-Transferrin-Selenium might be a better alternative and might be used instead of fetal-bovinum-serum or an autologous host serum in order to preserve meniscal tissue, which precludes the necessity of obtaining host serum previously. Thus, viable meniscal transplantation would logistically be less complicated to perform.

Effect of IL-1beta, PGE(2), and TGF-beta1 on the expression of OPG and RANKL in normal and osteoporotic primary human osteoblasts

The RANKL/RANK/OPG pathway is essential for bone remodeling regulation. Many hormones and cytokines are involved in regulating gene expression in most of the pathway components. Moreover, any deregulation of this pathway can alter bone metabolism, resulting in loss or gain of bone mass. Whether osteoblasts from osteoporotic and nonosteoporotic patients respond differently to cytokines is unknown. The aim of this study was to compare the effect of interleukin (IL)-1beta, proftaglandin E(2) (PGE(2)), and transforming growth factor-beta1 (TGF-beta1) treatments on OPG and RANKL gene expression in normal (n = 11) and osteoporotic (n = 8) primary osteoblasts. OPG and RANKL mRNA levels of primary human osteoblastic (hOB) cell cultures were assessed by real-time PCR. In all cultures, OPG mRNA increased significantly in response to IL-1beta treatment and decreased in response to TGF-beta1 whereas PGE(2) treatment had no effect. RANKL mRNA levels were significantly increased by all treatments. Differences in OPG and RANKL responses were observed between osteoporotic and nonosteoporotic hOB: in osteoporotic hOB, the OPG response to IL-1beta treatment was up to three times lower (P = 0.009), whereas that of RANKL response to TGF-beta1 was five times higher (P = 0.002) after 8 h of treatment, as compared with those in nonosteoporotic hOBs. In conclusion, osteoporotic hOB cells showed an anomalous response under cytokine stimulation, consistent with an enhanced osteoclastogenesis resulting in high levels of bone resorption.

In vivo evaluation of 3-dimensional polycaprolactone scaffolds for cartilage repair in rabbits

BACKGROUND

Cartilage tissue engineering using synthetic scaffolds allows maintaining mechanical integrity and withstanding stress loads in the body, as well as providing a temporary substrate to which transplanted cells can adhere.

PURPOSE

This study evaluates the use of polycaprolactone (PCL) scaffolds for the regeneration of articular cartilage in a rabbit model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Five conditions were tested to attempt cartilage repair. To compare spontaneous healing (from subchondral plate bleeding) and healing due to tissue engineering, the experiment considered the use of osteochondral defects (to allow blood flow into the defect site) alone or filled with bare PCL scaffold and the use of PCL-chondrocytes constructs in chondral defects. For the latter condition, 1 series of PCL scaffolds was seeded in vitro with rabbit chondrocytes for 7 days and the cell/scaffold constructs were transplanted into rabbits' articular defects, avoiding compromising the subchondral bone. Cell pellets and bare scaffolds were implanted as controls in a chondral defect.

RESULTS

After 3 months with PCL scaffolds or cells/PCL constructs, defects were filled with white cartilaginous tissue; integration into the surrounding native cartilage was much better than control (cell pellet). The engineered constructs showed histologically good integration to the subchondral bone and surrounding cartilage with accumulation of extracellular matrix including type II collagen and glycosaminoglycan. The elastic modulus measured in the zone of the defect with the PCL/cells constructs was very similar to that of native cartilage, while that of the pellet-repaired cartilage was much smaller than native cartilage.

CONCLUSION

The results are quite promising with respect to the use of PCL scaffolds as aids for the regeneration of articular cartilage using tissue engineering techniques.

Polymorphisms and haplotypes across the osteoprotegerin gene associated with bone mineral density and osteoporotic fractures

Osteoprotegerin plays a key role in bone remodelling. We studied the association between 24 polymorphisms and haplotypes on the OPG gene and bone mineral density and fractures. After multiple-testing correction, one SNP and two block-haplotypes were significantly associated with FN BMD. Two other block-haplotypes were associated with fracture.

INTRODUCTION AND HYPOTHESIS

Osteoprotegerin (OPG) plays a key role in bone remodelling. Here we studied the association between polymorphisms and haplotypes on the OPG gene and bone mineral density (BMD) and fractures.

METHODS

Twenty-four single nucleotide polymorphisms (SNPs) were selected to cover six haplotypic blocks and were genotyped in 964 postmenopausal Spanish women. Haplotypes were established with HaploStats. Association was analysed by GLM (for BMD) and logistic regression (for fractures) both at single SNP and haplotype levels.

RESULTS

Upon adjustment for multiple testing (p < 0.0073), one of the SNPs (SNP #17, rs1032129) remained significantly associated with FN BMD (p = 0.001). Four block-haplotypes stood multiple-testing correction. Two remained associated with FN BMD and two with fracture. The association of block-4 haplotype "AC" (of SNPs #18 and #17) with FN BMD (p = 0.0002) was stronger than that of SNP#17 alone and was the best result overall. A global assessment of the results indicated that all the alleles and haplotypes with a protective effect, at p < 0.05, belonged to a frequent long-range haplotype.

CONCLUSIONS

In conclusion, these results provide a detailed picture of the involvement of common variants and haplotypes of the OPG gene in bone phenotypes.

Biodegradable PCL scaffolds with an interconnected spherical pore network for tissue engineering

A technique for producing controlled interconnected porous structures for application as a tissue engineering scaffold is presented in this article. The technique is based on the fabrication of a template of interconnected poly(ethyl methacrylate) (PEMA) microspheres, the introduction of a biodegradable polymer, poly-epsilon-caprolactone (PCL), and the elimination of the template by a selective solvent. A series of PCL scaffolds with a porosity of 70% and pore sizes up to 200 microm were produced and characterized (both thermally and mechanically). Human chondrocytes were cultured in monolayer on bulk PCL disks or seeded into porous PCL scaffolds. Cell adhesion, viability, proliferation, and proteoglycan (PG) synthesis were tested and compared with monolayer cultures on tissue-treated polystyrene or pellet cultures as reference controls. Cells cultured on PCL disks showed an adhesion similar to that of the polystyrene control (which allowed high levels of proliferation). Stained scaffold sections showed round-shaped chondrocyte aggregates embedded into porous PCL. PG production was similar to that of the pellet cultures and higher than that obtained with monolayer postconfluence cultures. This shows that the cells are capable of attaching themselves to PCL. Furthermore, in porous PCL, cells maintain the same phenotype as the chondrocytes within the native cartilage. These results suggest that PCL scaffolds may be a suitable candidate for chondrocyte culture.

A porous PCL scaffold promotes the human chondrocytes redifferentiation and hyaline-specific extracellular matrix protein synthesis

The redifferentiation, proliferation, and hyaline-specific extracellular matrix (ECM) protein synthesis of chondrocytes cultured in a polycaprolactone (PCL) scaffold were analyzed. Gene expression of the type II collagen and aggrecan was assessed by real-time PCR in cells from PCL scaffolds, monolayer, and pellet cultures. The proliferative activity was assessed using Ki-67 immunodetection, and the chondrocytic differentiation was evaluated using S-100 immunodetection. The synthesis and deposition into scaffold pores of type II collagen and glycosaminoglycan were analyzed by immunohistochemistry and Alcian blue staining, respectively. All parameters were assessed throughout 28 days of cultures maintained in either fetal bovine serum-containing medium (FCM) or Insulin-Transferrin-Selenium-containing medium (ICM). Expression of the type II collagen gene was lower in FCM cultures than in ICM cultures for all culture systems (p < 0.05). Moreover, PCL scaffolds cultured in ICM were able to induce collagen gene expression more efficiently than pellet and monolayer cultures. Aggrecan gene expression did not vary significantly between mediums and three-dimensional system cultures, but in ICM cultures, the monolayer cultures had significantly higher levels of aggrecan gene expression than did either the PCL or pellet cultures. Chondrocytes cultured in PCL scaffolds or pellets with FCM did not proliferate to a great extent but did maintain their differentiated phenotype for 28 days. Levels of cartilage ECM protein synthesis and deposition into the scaffold pores were similar among PCL and pellet cultures grown in FCM and in ICM. In conclusion, chondrocytes seeded into PCL scaffolds, cultured in ICM, efficiently maintained their differentiated phenotype and were able to synthesize cartilage-specific ECM proteins.

Biochemical basis of the effect of chondroitin sulphate on osteoarthritis articular tissues

Osteoarthritis is a chronic disease characterised by irreversible damage to joint structures, including loss of articular cartilage, osteophyte formation, alterations in the subchondral bone and synovial inflammation. Pain, functional disability and impairment of health-related quality of life are major complaints in patients with osteoarthritis. Several compounds have been investigated for their positive effects on the relief of clinical symptoms and improvement of structural changes in osteoarthritis. It has been shown that chondroitin sulphate interferes with the progression of structural changes in joint tissues and is used in the management of patients with osteoarthritis. This review summarises data from relevant reports describing the mechanisms of action of chondroitin sulphate involved in the beneficial effects of the drug.

Decreased metalloproteinase production as a response to mechanical pressure in human cartilage: a mechanism for homeostatic regulation

Articular cartilage is optimised for bearing mechanical loads. Chondrocytes are the only cells present in mature cartilage and are responsible for the synthesis and integrity of the extracellular matrix. Appropriate joint loads stimulate chondrocytes to maintain healthy cartilage with a concrete protein composition according to loading demands. In contrast, inappropriate loads alter the composition of cartilage, leading to osteoarthritis (OA). Matrix metalloproteinases (MMPs) are involved in degradation of cartilage matrix components and have been implicated in OA, but their role in loading response is unclear. With this study, we aimed to elucidate the role of MMP-1 and MMP-3 in cartilage composition in response to mechanical load and to analyse the differences in aggrecan and type II collagen content in articular cartilage from maximum- and minimum-weight-bearing regions of human healthy and OA hips. In parallel, we analyse the apoptosis of chondrocytes in maximal and minimal load areas. Because human femoral heads are subjected to different loads at defined sites, both areas were obtained from the same hip and subsequently evaluated for differences in aggrecan, type II collagen, MMP-1, and MMP-3 content (enzyme-linked immunosorbent assay) and gene expression (real-time polymerase chain reaction) and for chondrocyte apoptosis (flow cytometry, bcl-2 Western blot, and mitochondrial membrane potential analysis). The results showed that the load reduced the MMP-1 and MMP-3 synthesis (p < 0.05) in healthy but not in OA cartilage. No significant differences between pressure areas were found for aggrecan and type II collagen gene expression levels. However, a trend toward significance, in the aggrecan/collagen II ratio, was found for healthy hips (p = 0.057) upon comparison of pressure areas (loaded areas > non-loaded areas). Moreover, compared with normal cartilage, OA cartilage showed a 10- to 20-fold lower ratio of aggrecan to type II collagen, suggesting that the balance between the major structural proteins is crucial to the integrity and function of the tissue. Alternatively, no differences in apoptosis levels between loading areas were found – evidence that mechanical load regulates cartilage matrix composition but does not affect chondrocyte viability. The results suggest that MMPs play a key role in regulating the balance of structural proteins of the articular cartilage matrix according to local mechanical demands.

Haplotypes defined by promoter and intron 1 polymorphisms of the COLIA1 gene regulate bone mineral density in women

CONTEXT

The COLIA1 gene is a strong candidate for susceptibility to osteoporosis. The causal genetic variants are currently unclear, but the most likely are functional polymorphisms in the promoter and intron 1 of COLIA1.

OBJECTIVE

The objective of the study was to determine whether promoter and intron 1 polymorphisms of COLIA1 or haplotypes defined by these polymorphisms regulate bone mineral density (BMD) in women.

DESIGN

This was a population-based association study involving 3270 women from the United Kingdom who took part in a regional osteoporosis screening program.

MAIN OUTCOME MEASURES

BMD at the lumbar spine (LS-BMD) and femoral neck (FN-BMD) was measured on two occasions approximately 6 yr apart, in relation to polymorphisms and haplotypes defined by polymorphisms within the COLIA1 intron 1 (+1245G/T; rs1800012) and promoter (-1997G/T; rs1107946; -1663IndelT; rs2412298).

RESULTS

The polymorphisms were in strong linkage disequilibrium, and three haplotypes accounted for more than 95% of alleles at the COLIA1 locus. The individual polymorphisms were associated with BMD, but the most consistent associations were with haplotypes defined by all three polymorphisms. Homozygote carriers of haplotype 2 (-1997G/-1663delT/+1245T) had reduced BMD at baseline (P = 0.007 for LS-BMD; P = 0.008 for FN-BMD), whereas homozygotes for haplotype 3 (-1997T/-1663insT/+1245G) had increased BMD (P = 0.007 for LS-BMD). Similar associations were observed at follow-up for haplotype 3, but the association with haplotype 2 was weaker due to increased uptake of hormone replacement therapy in homozygotes for this haplotype.

CONCLUSIONS

Two haplotypes defined by polymorphisms in the 5' flank of the COLIA1 regulate BMD in a bidirectional manner in women.

A new SNP in a negative regulatory region of the CYP19A1 gene is associated with lumbar spine BMD in postmenopausal women

Osteoporosis is a common disease of bone possessing a strong genetic component. Cytochrome P450 aromatase, which is encoded by the CYP19A1 gene, converts androgens to estradiol. Considerable evidence suggests that extragonadal estrogens play an important role in determining bone mineral density (BMD) in postmenopausal women, and, among them, those synthesized in bone cells may also be important for the determination of bone phenotype. Therefore, CYP19A1 is an excellent candidate gene for osteoporosis. Since a region upstream of exon I.3, including exon I.6, was identified as containing repressor elements of promoter pII, we conducted a search for SNPs in this region of CYP19A1. Two SNPs [Aro1(rs4775936) and Aro2] located in exon I.6 and promoter I.6, respectively, were identified and their association with BMD analyzed in a cohort of 256 Spanish postmenopausal women. Aro1(rs4775936), but not Aro2, was associated with lumbar spine BMD (P = 0.029). Homozygotes AA (16% of the women) exhibited significantly higher lumbar spine BMD, compared with GG or GA individuals. Therefore, this study describes the Aro1 polymorphism which lies within a regulatory region and which may be a functional polymorphism, partially responsible for the bone phenotype it is associated with.

Response of human chondrocytes to a non-uniform distribution of hydrophilic domains on poly (ethyl acrylate-co-hydroxyethyl methacrylate) copolymers

A series of polymer and copolymer networks with varying hydrophilicity and distribution of the hydrophilic groups was synthesized and biologically tested with monolayer culture of human chondrocytes in vitro. Cell viability (MTT), proliferation (BrdU incorporation) and aggrecan expression (PG ELISA) were quantified at 7 and 14 days from seeding. Both assays (MTT and BrdU) showed complementary results that are consistent with positive cellular adhesion on the material. When human chondrocytes were cultured on polymer substrates in which the hydrophilic groups were homogeneously distributed, hydrophobic substrates showed higher values in all the biological parameters analysed. Adhesion, proliferation and viability decreased monotonously with the content of hydrophilic groups in the polymer chain. However poly(ethyl acrylate-co-hydroxyethyl methacrylate) copolymers, in which hydrophilic and hydrophobic nano-domains alternate as phase-separated domains, showed better results than the corresponding homopolymers.

Functional analysis of the I.3, I.6, pII and I.4 promoters of CYP19 (aromatase) gene in human osteoblasts and their role in vitamin D and dexamethasone stimulation

OBJECTIVE

Current evidence suggests that extragonadal estrogens play an important role in bone metabolism. Estrogen biosynthesis is catalyzed by P450aromatase, encoded by the CYP19 gene. The aims of this paper were to study CYP19 gene expression in human osteoblasts under several hormone and cytokine treatments and to define promoter regions involved in this regulation.

METHODS

CYP19 transcript levels were measured from primary human osteoblasts and MG-63 cells by real-time PCR in basal conditions, and in response to seven different hormones and cytokines. Four promoters of CYP19 gene were cloned upstream of the luciferase gene and transfected into MG-63 cells. The effect of vitamin D and dexamethasone in these promoter activities was evaluated.

RESULTS

Vitamin D and dexamethasone were potent stimulators of CYP19 transcription, while testosterone and 17beta-estradiol stimulated moderately. Promoter pII proved the most potent in driving transient luciferase expression. Promoter I.4 displayed moderate activity, while promoters I.3 and I.6 were weak. A region upstream of exon I.3, including exon I.6, was identified as containing repressor elements of promoter pII. Promoter I.3 activity was modulated by repressors located within exon I.3, while an enhancer of promoter I.4 was detected within exon I.4. In the absence of fetal calf serum, dexamethasone stimulation was observed on promoters I.3 and I.4, while vitamin D stimulation acted only on promoter I.3.

CONCLUSIONS

Four regulatory regions of promoters pII, I.3 and I.4 are relevant to CYP19 expression in human osteoblasts. Vitamin D and dexamethasone modulate transcription through these regions.

Regulation of CYP19 gene expression in primary human osteoblasts: effects of vitamin D and other treatments

OBJECTIVE

Extragonadal estrogen biosynthesis is relevant for the regulation of bone metabolism. The aims of this paper were: (i) to examine CYP19 (aromatase) gene expression in primary cultures of osteoblasts under several hormone and cytokine treatments and (ii) to study the promoter usage of CYP19 in these cells.

METHODS

Primary cultures of osteoblasts were obtained from healthy donors. The effects of vitamin D and other factors on CYP19 expression were analysed by semiquantitative RT-PCR. Furthermore, CYP19 alternative promoter usage under the different treatments was characterized by RT-PCR.

RESULTS

CYP19 transcripts were detected in cultured human osteoblasts in serum-free conditions. Vitamin D, dexamethasone, 17beta-estradiol and testosterone increased transcript levels of CYP19, whereas interleukin-1beta or tumor necrosis factor alpha decreased them. Aromatase mRNA produced under treatment with vitamin D was transcribed from promoters I.4 and I.3, while stimulation with dexamethasone or dexamethasone plus vitamin D also involved promoter I.2. Testosterone activated promoters I.2 and I.4.

CONCLUSIONS

Our results suggested that vitamin D, testosterone, estrogens and glucocorticoids regulate CYP19 gene expression in human primary osteoblasts and the main promoter used appears to be promoter I.4. Promoters pII and I.3 seem to be related to basal transcription and may mediate estrogen stimulation, while promoter I.2 seems to play a role in the effect of glucocorticoids. These findings indicate that vitamin D and several hormones regulate local estrogen synthesis in human osteoblasts mainly through usage of promoters I.4 and I.3.

Two new single-nucleotide polymorphisms in the COL1A1 upstream regulatory region and their relationship to bone mineral density

Single-nucleotide polymorphisms (SNPs) in regulatory regions of candidate genes may determine variability in bone mineral density (BMD) because they may be responsible for differences in levels of a gene product in response to external signals. Under this hypothesis, we scanned an 800-base pair (bp) region within the COL1A1 promoter, known to harbor cis elements important for in vivo expression, and we found two new polymorphisms: -1663indelT and -1997 G/T. The G to T transversion at -1997 was associated with lumbar spine BMD (p = 0.015) when tested in a cohort of 256 postmenopausal women after adjusting by age, body weight, and years since menopause; a lower degree of association was detected also for femoral neck BMD in a subgroup of 146 women in univariate analysis and after adjusting by age (p = 0.044). The polymorphism -1663indelT, which corresponds to a deletion of a T in a tract of eight T residues (-1670 to -1663), did not show significant association with BMD. Interestingly, -1663indelT is in strong linkage disequilibrium (LD) with the previously described Sp1 polymorphism of intron 1, which in this study did not show association with BMD either. Significant interaction between -1997 G/T and -1663indelT (p = 0.019), and between -1997 G/T and Sp1 (p = 0.045) was observed also. Individuals heterozygous for the three polymorphisms showed the highest mean BMD value. Gel retardation assays showed that oligonucleotides containing either the -1663 or the -1997 polymorphic sites specifically bind primary osteoblast nuclear proteins. We named these binding sites as PCOL1 and PCOL2, respectively. In summary, this study describes two new SNPs in the COL1A1 promoter, which may affect bone mass determination.

Homocysteine and the MTHFR 677C-->T allele in premature coronary artery disease. Case control and family studies

BACKGROUND

The aim of this work was to evaluate the role of homocysteine, and the MTHFR 677C-->T allele as risk factors for premature coronary artery disease and to analyse the inheritance of this metabolic disorder.

MATERIAL AND METHODS

Case-control and family studies were performed in a sample of 76 male patients (age < 55), 95 age-matched controls and 89 patients' offspring. Plasma total homocysteine concentrations, its nutritional determinants and the frequency of the MTHFR 677C-->T allele were measured, in addition to conventional risk factors.

RESULTS

Mild hyperhomocysteinemia (above the 90th percentile of the control group) was seen in 22.4% of patients (P = 0.02) and was an independent predictor of premature coronary artery disease (odds ratio of 3.2). The frequencies of the 677T allele in patients and controls were 0.37 and 0.36 and those of the TT genotype were 0.15 and 0.14, respectively. Homozygosity for the 677T allele was associated with significantly higher homocysteine values (P < 0.00001). Among TT patients, 64% had mild hyperhomocysteinemia, as compared to 23% of TT controls. Mild hyperhomocysteinemia showed a strong hereditary component, as 36% of patients' offspring had homocysteine levels above the age-adjusted 90th percentile compared to only 13% of patients' spouses. Among children with the TT genotype, the proportion raised to 83% (P < 0.001).

CONCLUSION

In this Spanish population, mild hyperhomocysteinemia is associated with the risk of premature coronary artery disease and is highly prevalent in offspring of patients with this condition. The MTHFR TT genotype is associated with hyperhomocysteinemia, but not with coronary artery disease.

Mutation 1091delC is highly prevalent in Spanish Sanfilippo syndrome type A patients

The gene resposible for Sanfilippo syndrome type A, a lysosomal disorder caused by deficiency of sulfamidase, was recently cloned and more than 40 mutations were identified. This paper presents the mutation analysis and clinical findings in 11 Spanish patients in whom 19 of the 22 mutant alleles have been identified. This is the first report on mutations in Spanish Sanfilippo A patients. Seven different mutations were found, four of which (Q85R, R206P, A354P, and L386R) were not previously described. Mutation 1091delC was the most prevalent, accounting for nearly one-half of the mutated alleles, while mutations R245H and R74C were not found. Haplotype analysis suggests a founder effect as the cause of the high frequency of 1091delC in this population.