Fracture prediction in rheumatoid arthritis: validation of FRAX with bone mineral density for incident major osteoporotic fractures.

OBJECTIVES: FRAX® uses clinical risk factors, with or without bone mineral density (BMD), to calculate 10-year fracture risk. Rheumatoid arthritis (RA) is a risk factor for osteoporotic fracture and a FRAX input variable. FRAX predates the current era of RA treatment. We examined how well FRAX predicts fracture in contemporary RA patients. METHODS: Administrative data from patients receiving BMD testing were linked to the Manitoba Population Health Research Data Repository. Observed cumulative 10-year Major Osteoporotic Fracture (MOF) probability was compared with FRAX-predicted 10-year MOF probability with BMD for assessing calibration. MOF risk stratification was assessed using Cox regression. RESULTS: RA patients (N = 2,099, 208 with incident MOF) and non-RA patients (N = 2,099, with 165 incident MOF) were identified. For RA patients, FRAX predicted 10-year risk was 13.2% and observed 10-year MOF risk was 13.2% (95% CI 11.6% to 15.1%). The slope of the calibration plot was 0.67 (95% CI 0.53-0. 81) in those with RA vs 0.98 (95% CI 0.61-1.34) in non-RA patients. Risk was overestimated in RA patients with high FRAX scores (>20%), but FRAX was well-calibrated in other groups. FRAX stratified risk in those with and without RA (hazard ratios 1.52, 95% 1.25-1.72 vs 2.00, 95% 1.73-2.31), with slightly better performance in the latter (p-interaction = 0.004). CONCLUSIONS: FRAX predicts fracture risk in contemporary RA patients but may slightly overestimate risk in those already at high predicted risk. Thus, the current FRAX tool continues to be appropriate for fracture risk assessment in RA patients.

Rapid Internalization of Nanoparticles by Human Cells at the Single Particle Level.

Nanoparticle uptake by cells has been studied for applications both in nanomedicine and in nanosafety. While the majority of studies have focused on the biological mechanisms underlying particle internalization, less attention has been given to questions of a more quantitative nature, such as how many nanoparticles enter cells and how rapidly they do so. To address this, we exposed human embryonic kidney cells to 40-200 nm carboxylated polystyrene nanoparticles and the particles were observed by live-cell confocal and super-resolution stimulated emission depletion fluorescence microscopy. How long a particle remained at the cell membrane after adsorbing onto it was monitored, distinguishing whether the particle ultimately desorbed again or was internalized by the cell. We found that the majority of particles desorb, but interestingly, most of the particles that are internalized do so within seconds, independently of particle size. As this is faster than typical endocytic mechanisms, we interpret this observation as the particles entering via an endocytic event that is already taking place (as opposed to directly triggering their own uptake) or possibly via an as yet uncharacterized endocytic route. Aside from the rapidly internalizing particles, a minority of particles remain at the membrane for tens of seconds to minutes before desorbing or being internalized. We also followed particles after cell internalization, observing particles that appeared to exit the cell, sometimes as rapidly as within tens of seconds. Overall, our results provide quantitative information about nanoparticle cell internalization times and early trafficking.

The effect of biomolecular corona on adsorption onto and desorption from a model lipid membrane.

The current lack of insight into nanoparticle-cell membrane interactions hampers smart design strategies and thereby the development of effective nanodrugs. Quantitative and methodical approaches utilizing cell membrane models offer an opportunity to unravel particle-membrane interactions in a detailed manner under well controlled conditions. Here we use total internal reflection microscopy for real-time studies of the non-specific interactions between nanoparticles and a model cell membrane at 50 ms temporal resolution over a time course of several minutes. Maintaining a simple lipid bilayer system across conditions, adsorption and desorption were quantified as a function of biomolecular corona, particle size and fluid flow. The presence of a biomolecular corona reduced both the particle adsorption rate onto the membrane and the duration of adhesion, compared to pristine particle conditions. Particle size, on the other hand, was only observed to affect the adsorption rate. The introduction of flow reduced the number of adsorption events, but increased the residence time. Lastly, altering the composition of the membrane itself resulted in a decreased number of adsorption events onto negatively charged bilayers compared to neutral bilayers. Overall, a model membrane system offers a facile platform for real-time imaging of individual adsorption-desorption processes, revealing complex adsorption kinetics, governed by particle surface energy, size dependent interaction forces, flow and membrane composition.

Trabecular Bone Score in Rheumatic Disease.

PURPOSE OF REVIEW: Patients with rheumatic disease are at high risk of low bone mass and osteoporotic fracture. Trabecular bone score (TBS), derived from lumbar spine dual-energy x-ray absorptiometry (DXA), is a novel measure of bone texture that independently predicts fracture risk. This review examines the role of TBS in rheumatic disease including fracture prediction. RECENT FINDINGS: Most studies concerning TBS and rheumatic disease are cross-sectional, with consistent evidence of lower TBS in patients with rheumatic disease compared to controls. Recent studies have shown association and predictive ability of TBS for prevalent fracture, and the few longitudinal studies showed predictive ability of TBS for incident fracture. TBS in ankylosing spondylitis is of interest given the high rates of vertebral fracture and technical difficulty with lumbar spine bone mineral density. TBS degradation has been associated with disease activity in ankylosing spondylitis, systemic sclerosis, and rheumatoid arthritis. Glucocorticoid exposure is associated with lower TBS, and predicts prevalent fracture, in patients with rheumatic conditions.

Simultaneous Exposure of Different Nanoparticles Influences Cell Uptake.

Drug delivery using nano-sized carriers holds tremendous potential for curing a range of diseases. The internalisation of nanoparticles by cells, however, remains poorly understood, restricting the possibility for optimising entrance into target cells, avoiding off-target cells and evading clearance. The majority of nanoparticle cell uptake studies have been performed in the presence of only the particle of interest; here, we instead report measurements of uptake when the cells are exposed to two different types of nanoparticles at the same time. We used carboxylated polystyrene nanoparticles of two different sizes as a model system and exposed them to HeLa cells in the presence of a biomolecular corona. Using flow cytometry, we quantify the uptake at both average and individual cell level. Consistent with previous literature, we show that uptake of the larger particles is impeded in the presence of competing smaller particles and, conversely, that uptake of the smaller particles is promoted by competing larger particles. While the mechanism(s) underlying these observations remain(s) undetermined, we are partly able to restrain the likely possibilities. In the future, these effects could conceivably be used to enhance uptake of nano-sized particles used for drug delivery, by administering two different types of particles at the same time.

Trabecular Bone Score (TBS) Predicts Fracture in Ankylosing Spondylitis: The Manitoba BMD Registry.

INTRODUCTION: Ankylosing spondylitis (AS) is a chronic inflammatory disease of the spine characterized among other features by spinal boney proliferation, back pain, loss of flexibility, and increased fracture risk. Overlying bone limits the utility of bone mineral density (BMD) by dual X-ray absorptiometry (DXA) in the spine. Trabecular bone score (TBS) is a bone texture measurement derived from the spine DXA image that indicates bone quality and fracture risk independent of BMD. METHODOLOGY: Using the Manitoba Bone Density Program database, patients with diagnosis codes for ankylosing spondylitis, baseline DXA and lumbar spine TBS were identified. Incident nontraumatic fractures (major osteoporotic [MOF], clinical spine, hip, and all fracture) were identified from population based databases. Cox-proportional hazard models are presented. RESULTS: We identified 188 patients with diagnosed AS. TBS was lower in those with incident MOF (1.278 ± 0.126, compared to 1.178 ± 0.136, p < 0.001). Unadjusted TBS and FRAX-MOF-BMD adjusted predicted major osteoporotic fracture (N = 19) (hazard ratio [HR] 2.04, 95% confidence interval [CI]: 1.28-2.26, p = 0.003; HR 1.81, 95% CI: 1.11-2.96, p = 0.018). TBS unadjusted and FRAX-MOF-BMD adjusted also predicted clinical spine fracture (N = 7) (HR 2.50, 95% CI: 1.17-5.37; p = 0.019; HR 2.40 95% CI: 1.1-5.25; p = 0.028). Higher HRs were observed for prediction of hip fracture (N = 6), but these did not achieve statistical significance (FRAX-adjusted HR 1.74, 95% 0.73-4.17; p = 0.211). Unadjusted models show TBS was predictive of all fracture (N = 27) (HR 1.60, 95% CI: 1.08-2.39; p = 0.020), which was borderline significant after adjustment for FRAX-MOF-BMD (HR 1.51, 95% CI: 1.00-2.29; p = 0.052). CONCLUSION: We report the first analysis of TBS for fracture prediction as an incident event in AS. TBS independently predicted major osteoporotic and clinical spine fracture in AS independent of FRAX.

Methotrexate exposure and risk of strongyloidiasis.

OBJECTIVE: Rheumatologic disease patients receiving immunomodulating drugs such as methotrexate (MTX) have increased infection rates. Strongyloides, a global endemic intestinal parasite, can cause significant or fatal disease in immunocompromised patients. The risk of serious Strongyloides infection with MTX dosed for rheumatologic disease is unknown. METHODS: We performed a systematic literature review searching EMBASE, Medline and Web of Science databases. All studies reporting humans exposed to MTX and tested for Strongyloides were reviewed. Exclusion criteria were bone marrow transplantation, intrathecal route and MTX exposure completed >1 year prior to clinically apparent Strongyloides disease. RESULTS: After excluding duplicates, 294 articles were reviewed. Of these, 29 cases were described in 27 papers. Twenty cases (69%) had an underlying rheumatologic or dermatologic disease, the rest had a haematologic disease. Hyperinfection or dissemination was found in 59% of cases (52% low-dose MTX; 75% high-dose MTX). Death occurred in 34% of cases (19% low-dose MTX; 75% high-dose MTX, P < 0.01). All eight patients on high-dose MTX received other immunosuppressants. Corticosteroids were taken in 18/21 patients on low-dose MTX. One of the three patients on MTX monotherapy had hyperinfection syndrome. None had disseminated Strongyloides. CONCLUSIONS: Serious Strongyloides infection can occur with low-dose MTX particularly when given with other immunosuppression. Global travel and greater awareness of rheumatologic conditions in low- to middle-income countries will increase the exposure of individuals prescribed MTX (with or without corticosteroids) to Strongyloides. Strongyloides screening and treatment should be considered for individuals receiving low-dose MTX therapy, particularly if combined with additional immunosuppression.

OBJECTIF: Les patients atteints de maladies rhumatologiques recevant des médicaments immunomodulateurs tels que le méthotrexate (MTX) présentent des taux d'infection plus élevés. Strongyloides, un parasite intestinal endémique mondial, peut causer une maladie grave ou fatale chez les patients immunodéprimés. Le risque d'infection sévère à Strongyloides sous administration de MTX pour le traitement de la maladie rhumatologique est inconnu. MÉTHODES: Nous avons effectué une revue systématique de la littérature en recherchant les bases de données EMBASE, Medline et Web of Science. Toutes les études rapportant sur des humains exposés au MTX et testés pour Strongyloides ont été passées en revue. Les critères d'exclusion étaient la greffe de moelle osseuse, la voie intrathécale et l'exposition au MTX complétée plus d'un an avant l'apparition de la maladie à Strongyloides cliniquement apparente. RÉSULTATS: Après exclusion des doublons, 294 articles ont été analysés. Parmi ceux-ci, 29 cas ont été décrits dans 27 articles. Vingt cas (69%) avaient une maladie rhumatologique ou dermatologique sous-jacente, les autres avaient une maladie hématologique. Une hyperinfection ou dissémination a été constatée dans 59% des cas (52% sous MTX à faible dose; 75% sous MTX à forte dose). La mort est survenue dans 34% des cas (19% des cas sous MTX à faible dose; 75% des cas sous MTX à forte dose, p <0,01). Tous les huit patients ayant reçu une dose élevée de MTX avaient reçu d'autres immunosuppresseurs. Des corticostéroïdes ont été administrés à 18 patients sur 21 sous MTX à faible dose. Un des trois patients sous MTX en monothérapie avait un syndrome d'hyperinfection. Aucun n'avait une infection disséminée à Strongyloides. CONCLUSIONS: Une infection sévère à Strongyloides peut survenir avec le MTX à faible dose, en particulier lorsqu'administré avec une autre immunosuppression. Les voyages à travers le monde et une plus grande sensibilisation aux conditions rhumatologiques dans les pays à revenu faible et intermédiaire augmenteront l'exposition à Strongyloides chez les individus chez qui le MTX (avec ou sans corticostéroïdes) est prescrit. Le dépistage et le traitement de Strongyloides devraient être envisagés chez les personnes recevant un traitement au MTX à faible dose, en particulier lorsqu'associé à une immunosuppression supplémentaire.

The impact of vitamin D supplementation on musculoskeletal health outcomes in children, adolescents, and young adults living with HIV: A systematic review.

OBJECTIVE: HIV-positive children, adolescents, and young adults are at increased risk poor musculoskeletal outcomes. Increased incidence of vitamin D deficiency in youth living with HIV may further adversely affect musculoskeletal health. We investigated the impact of vitamin D supplementation on a range of musculoskeletal outcomes among individuals aged 0-25 years living with HIV. METHODS: A systematic review was conducted using databases: PubMed/Medline, CINAHL, Web of Knowledge, and EMBASE. Interventional randomised control trials, quasi-experimental trials, and previous systematic reviews/meta-analyses were included. Outcomes included: BMD, BMC, fracture incidence, muscle strength, linear growth (height-for-age Z-score [HAZ]), and biochemical/endocrine biomarkers including bone turnover markers. RESULTS: Of 497 records, 20 studies met inclusion criteria. Thirteen studies were conducted in North America, one in Asia, two in Europe, and four in Sub-Saharan Africa. High-dose vitamin D supplementation regimens (1,000-7,000 IU/day) were successful in achieving serum 25-hydroxyvitamin-D (25OHD) concentrations above study-defined thresholds. No improvements were observed in BMD, BMC, or in muscle power, force and strength; however, improvements in neuromuscular motor skills were demonstrated. HAZ was unaffected by low-dose (200-400 IU/day) supplementation. A single study found positive effects on HAZ with high-dose supplementation (7,000 vs 4,000IU/day). CONCLUSIONS: Measured bone outcomes were unaffected by high-dose vitamin D supplementation, even when target 25OHD measurements were achieved. This may be due to: insufficient sample size, follow-up, intermittent dosing, non-standardised definitions of vitamin D deficiency, or heterogeneity of enrolment criteria pertaining to baseline vitamin D concentration. High-dose vitamin D may improve HAZ and neuromuscular motor skills. Adequately powered trials are needed in settings where HIV burden is greatest. PROSPERO Number: CRD42016042938.