Tina Marie Kringelbach

The effect of PTH(1‐34) on fracture healing during different loading conditions

Parathyroid hormone (PTH) and PTH(1‐34) have been shown to promote bone healing in several animal studies. It is known that the mechanical environment is important in fracture healing. Furthermore, PTH and mechanical loading has been suggested to have synergistic effects on intact bone. The aim of the present study was to investigate whether the effect of PTH(1‐34) on fracture healing in rats was influenced by reduced mechanical loading. For this purpose, we used female, 25‐week‐old ovariectomized rats. Animals were subjected to closed midshaft fracture of the right tibia 10 weeks after ovariectomy. Five days before fracture, half of the animals received Botulinum Toxin A injections in the muscles of the fractured leg to induce muscle paralysis (unloaded group), whereas the other half received saline injections (control group). For the following 8 weeks, half of the animals in each group received injections of hPTH(1‐34) (20u2009µg/kg/day) and the other half received vehicle treatment. Fracture healing was assessed by radiology, dual‐energy X‐ray absorptiometry (DXA), histology, and bone strength analysis. We found that unloading reduced callus area significantly, whereas no effects of PTH(1‐34) on callus area were seen in neither normally nor unloaded animals. PTH(1‐34) increased callus bone mineral density (BMD) and bone mineral content (BMC) significantly, whereas unloading decreased callus BMD and BMC significantly. PTH(1‐34) treatment increased bone volume of the callus in both unloaded and control animals. PTH(1‐34) treatment increased ultimate force of the fracture by 63% in both control and unloaded animals and no interaction of the two interventions could be detected. PTH(1‐34) was able to stimulate bone formation in normally loaded as well as unloaded intact bone. In conclusion, the study confirms the stimulatory effect of PTH(1‐34) on fracture healing, and our data suggest that PTH(1‐34) is able to promote fracture healing, as well as intact bone formation during conditions of reduced mechanical loading.

UTP-induced ATP release is a fine-tuned signalling pathway in osteocytes

Osteocytes reside as a cellular network throughout the mineralised matrix of bone and are considered the primary mechanosensors of this tissue. They sense mechanical stimulation such as fluid flow and are able to regulate osteoblast and osteoclast functions on the bone surface. Previously, we found that ATP is released load-dependently from osteocytes from the onset of mechanical stimulation. Therefore, the aim of the present study was to investigate whether and how ATP release can be evoked in osteocytes via purinergic receptor activation. ATP release was quantified by real-time determination using the luciferin-luciferase assay and the release pathway was investigated using pharmacological inhibition. The P2Y receptor profile was analysed using gene expression analysis by reverse transcription polymerase chain reaction, while functional testing was performed using measurements of intracellular calcium responses to P2 receptor agonists. These investigations demonstrated that MLO-Y4 osteocytes express functional P2Y2, P2Y4, P2Y12 and P2Y13 receptors in addition to the previously reported P2X receptors. Further, we found that osteocytes respond to nucleotides such as ATP, UTP and ADP by increasing the intracellular calcium concentration and that they release ATP dose-dependently upon stimulation with 1–10xa0μM UTP. In addition to this, osteocytes release large amounts of ATP upon cell rupture, which might also be a source for other nucleotides, such as UTP. These findings indicate that mechanically induced ATP signals may be propagated by P2 receptor activation and further ATP release in the osteocyte network and implicate purinergic signalling as a central signalling pathway in osteocyte mechanotransduction.

Fine-tuned ATP signals are acute mediators in osteocyte mechanotransduction.

Osteocytes are considered the primary mechanosensors of bone, but the signaling pathways they apply in mechanotransduction are still incompletely investigated and characterized. A growing body of data strongly indicates that P2 receptor signaling among osteoblasts and osteoclasts has regulatory effects on bone remodeling. Therefore, we hypothesized that ATP signaling is also applied by osteocytes in mechanotransduction. We applied a short fluid pulse on MLO-Y4 osteocyte-like cells during real-time detection of ATP and demonstrated that mechanical stimulation activates the acute release of ATP and that these acute ATP signals are fine-tuned according to the magnitude of loading. ATP release was then challenged by pharmacological inhibitors, which indicated a vesicular release pathway for acute ATP signals. Finally, we showed that osteocytes express functional P2X2 and P2X7 receptors and respond to even low concentrations of nucleotides by increasing intracellular calcium concentration. These results indicate that in osteocytes, vesicular ATP release is an acute mediator of mechanical signals and the magnitude of loading. These and previous results, therefore, implicate purinergic signaling as an early signaling pathway in osteocyte mechanotransduction.

Drug concentrations and anti-drug antibodies during treatment with biosimilar infliximab (CT-P13) in routine care

The Danish Rheumatologic Biobank, the DANBIO Registry and Copenhagen Center for Arthritis Research (COPECARE), Center for Rheumatology and Spine Diseases, Centre of Head and Orthopaedics, Rigshospitalet, Glostrup, Denmark Department of Rheumatology, Gentofte and Herlev Hospital, Copenhagen University Hospital, Gentofte, Denmark The Danish Rheumatologic Biobank, Department of Pathology, Herlev and Gentofte Hospital, Copenhagen University Hospital, Herlev, Denmark Department of Medical Biochemistry, Oslo University Hospital, Radiumhospitalet, Oslo, Norway Department of Rheumatology, Zealand University Hospital, Køge, Denmark Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark Department of Rheumatology, Aarhus University Hospital, Aarhus, Denmark King Christian X’s Hospital for Rheumatic Diseases, Graasten, Denmark Department of Rheumatology, Odense University Hospital, Svendborg Hospital, Svendborg, Denmark Department of Rheumatology, North Denmark Regional Hospital, Hjørring, Denmark Department of Rheumatology, Aalborg University Hospital, Aalborg, Denmark Department of Rheumatology, Odense University Hospital, Odense, Denmark Department of Rheumatology, Diakonhjemmet Hospital, Oslo, Norway The Danish Rheumatologic Biobank, Herlev and Gentofte Hospital, Copenhagen University Hospital, Herlev, Denmark Department of Medical Biochemistry, Oslo University Hospital, Radiumhospitalet, Norway Center for Rheumatology and Spine Diseases, Institute for Inflammation Research (IIR), Rigshospitalet, Copenhagen University Hospital, Glostrup, Denmark Zitelab, Copenhagen, Denmark Department of Medicine and Oncology, Herlev and Gentofte Hospital, Copenhagen University Hospital, Herlev, Denmark

Identification of new biomarkers to promote personalised treatment of patients with inflammatory rheumatic disease: protocol for an open cohort study

Introduction The introduction of biological disease-modifying antirheumatic drugs (bDMARDs) has improved the treatment of inflammatory rheumatic diseases dramatically. However, bDMARD treatment failure occurs in 30%–40% of patients due to lack of effect or adverse events, and the tools to predict treatment outcomes in individual patients are currently limited. The objective of the present study is to identify diagnostic, prognostic and predictive biomarkers, which can be used to (1) diagnose inflammatory rheumatic diseases early in the disease course with high sensitivity and specificity, (2) improve prognostication or (3) predict and monitor treatment effectiveness and tolerability for the individual patient. Methods and analysis The present study is an observational and translational open cohort study with prospective collection of clinical data and biological materials (primarily blood) in patients with inflammatory rheumatic diseases treated in routine care. Patients contribute with one cross-sectional blood sample and/or are enrolled for longitudinal follow-up on initiation of a new DMARD (blood sampling after 0, 3, 6, 12, 24, 36, 48, 60 months of treatment). Other biological materials will be collected when accessible and relevant. Demographics, disease characteristics, comorbidities and lifestyle factors are registered at inclusion; DMARD treatment and outcomes are collected repeatedly during follow-up. Currently (July 2017), >5000 samples from approximately 3000 patients have been collected. Data will be analysed using appropriate statistical analyses. Ethics and dissemination The protocol is approved by the Danish Ethics Committee and the Danish Data Protection Agency. Participants give written and oral informed consent. Biomarkers will be evaluated and published according to the Reporting Recommendations for Tumour Marker (REMARK) prognostic studies, Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) and the Standards for Reporting of Diagnostic Accuracy (STARD) guidelines. Results will be published in peer-reviewed scientific journals and presented at international conferences. Trial registration number NCT03214263.

Non-medical switch from originator to biosimilar infliximab in patients with inflammatory arthritis: impact on s-infliximab and antidrug-antibodies. Results from the Danish Rheumatologic Biobank and the DANBIO registry

3 OP04 HLA-B27 status is associated with TNF-α inhibitor treatment outcomes in ankylosing spondylitis and non radiographic axial spondyloarthritis. An observational cohort study from the nationwide DANBIO registry B Glintborg, IJ Sørensen, M Østergaard, NS Krogh, AA Mohamoud, LS Andersen, JL Raun, O Hendricks, MR Kowalski, L Danielsen, SR Christensen, N Al Chaer, R Pelck, H Nordin, JK Pedersen, DGA Kraus, IMJ Hansen, J Espesen, A Schlemmer, AG Loft, L Salomonsen, L Dreyer, ML Hetland