miR-23a contributes to T cellular redox metabolism in juvenile idiopathic oligoarthritis.

OBJECTIVE: JIA is a chronic inflammatory disease of unknown origin. The regulation of inflammatory processes involves multiple cellular steps including mRNA transcription and translation. Different miRNAs control these processes tightly. We aimed to determine the roles of specific miRNAs within JIA pathogenesis. METHODS: We performed a global miRNA expression analysis in parallel in cells from the arthritic joint and peripheral blood of oligoarticular JIA patients and healthy controls. Quantitative RT-PCR analysis was used to verify expression of miRNA in T cells. Ex vivo experiments and flow cytometric analyses were used to analyse proliferation and redox metabolism. RESULTS: Global miRNA expression analysis demonstrated a different composition of miRNA expression at the site of inflammation compared with peripheral blood. Bioinformatic analysis of predicted miRNA target genes suggest a huge overrepresentation of genes involved in metabolic and oxidative stress pathways in the inflamed joint. Despite enhanced reactive oxygen species (ROS) levels within the local inflammatory milieu, JIA T cells are hyperproliferative and reveal an overexpression of miR-23a, which is an inhibitor of Peptidyl-prolyl isomerase F (PPIF), the regulator of mitochondrial ROS escape. Mitochondrial ROS escape is diminished in JIA T cells, resulting in their prolonged survival. CONCLUSION: Our data suggest that miRNA-dependent mitochondrial ROS shuttling might be a mechanism that contributes to T cell regulation in JIA at the site of inflammation.

Automated Greulich-Pyle bone age determination in children with chronic kidney disease.

BACKGROUND: Growth restriction and retarded bone age are common findings in children with chronic kidney disease (CKD). We compared the automated BoneXpert™ method with the manual assessment of an X-ray of the non-dominant hand. METHODS: In this retrospective multicenter study, 359 patients with CKD stages 2-5, aged 2-14.5 (girls) or 2.5-17 years (boys) were included. Bone age was determined manually by three experts (according to Greulich and Pyle). Automated determination of bone age was performed using the image analysis software BoneXpert™. RESULTS: There was a strong correlation between the automatic and the manual method (r = 0.983, p < 0.001). The automatic method tended to generate higher bone age values (0.64 ± 0.73 years) in the younger patients (4-5 years) and to underestimate retardation or acceleration of bone age. The so-called "bone health index" (BHI) was reduced in comparison to the reference population. Bone health index standard deviation score (BHI-SDS) was not related to the stage of CKD, but weakly negatively correlated with plasma PTH concentrations (r = 0.12, p = 0.019). CONCLUSIONS: BoneXpert™ allows an objective, time-saving, and in general valid bone age assessment in children with CKD. Possible underestimation of retarded or accelerated bone age should be taken into account. Validation of the BHI needs further study.

Participation in school sports among children and adolescents with juvenile idiopathic arthritis in the German National Paediatric Rheumatologic Database, 2000-2015: results from a prospective observational cohort study.

BACKGROUND: Regular school sports can help adolescents achieve the recommended amount of daily physical activity and provide knowledge, attitudes and behavioral skills that are needed in order to adopt and maintain a physically active lifestyle. Furthermore, it reaches all children including those that are at risk for engaging in more sedentary types of behavior. Since adolescents with juvenile idiopathic arthritis (JIA) are less involved in physical and social activities than their healthy peers, the objectives were to (1) estimate the prevalence of participation in school sports among patients with JIA; (2) determine the correlates associated with school sports absenteeism; and (3) investigate whether attendance in school sports has changed in the era of biologics. METHODS: Data from schoolchildren with JIA recorded in the German National Paediatric Rheumatologic Database (NPRD) in the years 2000 to 2015 were considered for the analyses. Data from the year 2015 were inspected to analyze correlates of school sports absenteeism. Whether school sports participation had changed between 2000 and 2015 was determined using linear mixed models. RESULTS: During the 15-year period, the participation rates in school sports were determined in 23,016 patients. The proportion of patients who participated in school sports almost always steadily increased from 31% in 2000 to 64% in 2015 (ß = 0.017, 95% confidence interval (CI) 0.015, 0.020), whereas the exemption rate simultaneously decreased from 44% in 2000 to 16% in 2015 [ß = - 0.009, 95% CI -0.011, - 0.007]. In 2015, the data from 5879 patients (mean age 13.1 ± 3.3 years, female 65%, disease duration 5.9 ± 4.0 years, persistent oligoarthritis 37%) were available for evaluation. Full exemption from school sports (in 16.1% of cases) was associated with functional limitations, disease activity and any use of DMARDs, intra-articular glucocorticoid injections or physiotherapy. CONCLUSIONS: School sports attendance among children and adolescents with JIA has increased significantly over the past 15 years. Possible explanations include improved functional ability probably due to better treatment options. The integration of patients with child acceptable symptom states who have previously been fully exempted from school sports needs to be addressed in the future.

Treatment of systemic-onset juvenile arthritis with canakinumab.

Treatment of systemic-onset juvenile idiopathic arthritis is challenging, but the availability of cytokine antagonists targeting interleukin-1 and interleukin-6 have markedly advanced the therapeutic options. In this review, we focus on the current experience with canakinumab, an interleukin-1 monoclonal human antibody for the treatment of systemic-onset juvenile idiopathic arthritis and describe its efficacy and safety. Canakinumab is an important, safe, and valid drug in the treatment of systemic-onset juvenile idiopathic arthritis.

Elicitation of expert prior opinion: application to the MYPAN trial in childhood polyarteritis nodosa.

OBJECTIVES: Definitive sample sizes for clinical trials in rare diseases are usually infeasible. Bayesian methodology can be used to maximise what is learnt from clinical trials in these circumstances. We elicited expert prior opinion for a future Bayesian randomised controlled trial for a rare inflammatory paediatric disease, polyarteritis nodosa (MYPAN, Mycophenolate mofetil for polyarteritis nodosa). METHODS: A Bayesian prior elicitation meeting was convened. Opinion was sought on the probability that a patient in the MYPAN trial treated with cyclophosphamide would achieve disease remission within 6-months, and on the relative efficacies of mycophenolate mofetil and cyclophosphamide. Expert opinion was combined with previously unseen data from a recently completed randomised controlled trial in ANCA associated vasculitis. RESULTS: A pan-European group of fifteen experts participated in the elicitation meeting. Consensus expert prior opinion was that the most likely rates of disease remission within 6 months on cyclophosphamide or mycophenolate mofetil were 74% and 71%, respectively. This prior opinion will now be taken forward and will be modified to formulate a Bayesian posterior opinion once the MYPAN trial data from 40 patients randomised 1:1 to either CYC or MMF become available. CONCLUSIONS: We suggest that the methodological template we propose could be applied to trial design for other rare diseases.

The p38-mediated rapid down-regulation of cell surface gp130 expression impairs interleukin-6 signaling in the synovial fluid of juvenile idiopathic arthritis patients.

OBJECTIVE: Interleukin-6 (IL-6) signaling plays an important proinflammatory role, but this role is restricted by regulatory mechanisms that, for example, reduce the cell surface availability of the signal-transducing chain of the IL-6 receptor, gp130. The aim of this study was to determine whether the inflammatory environment in arthritic joints has an impact on monocytic gp130 surface expression and the extent to which regulatory processes in the synovial fluid (SF) can be reproduced in an in vitro model. METHODS: Flow cytometry and live cell imaging were used to measure the cell surface expression and internalization of gp130. STAT-3 phosphorylation was monitored by flow cytometry and Western blotting. RESULTS: In patients with juvenile idiopathic arthritis (JIA), levels of cell surface gp130 expression in SF monocytes were reduced compared to those in peripheral blood (PB) monocytes. These reduced levels were reproduced when PB monocytes from healthy donors were stimulated with SF, and this reduction was dependent on p38 MAPK. The induction of p38 by IL-1ß in PB monocytes interfered with IL-6 signaling due to the reduced cell surface expression of gp130. CONCLUSION: These results suggest that p38-mediated proinflammatory stimuli induce the down-regulation of gp130 on monocytes and thus restrict gp130-mediated signal transduction. This regulatory mechanism could be of relevance to processes in the inflamed joints of patients with JIA.

B cell depletion for autoimmune diseases in paediatric patients.

Data on B cell depletion therapy in severe autoimmune diseases in paediatric patients are very limited. We conducted a retrospective cohort study and recruited patients who were treated with rituximab (RTX) and followed up for at least 6 months through the German societies of paediatric rheumatology and nephrology. The aim was to describe the spectrum of autoimmune disorders for which RTX was used and to describe the applied therapeutic regimens, the observed efficacy, as well as potential immunological side effects. The need to develop standard treatment guidelines for future trials should be discussed. Sixty-five patients were included. Nineteen patients suffered from systemic lupus erythematosus, 13 from vasculitic disorders, 12 from hematological autoimmune diseases, 5 from mixed connective tissue disorders, 4 from juvenile idiopathic arthritis, and 9 had other autoimmune diseases. Adverse, infusion-related events were reported in 12/65 (18%) patients. Considering laboratory and clinical parameters, 13 patients (22%) were in complete remission, 31 (52%) were in partial remission, 6 (10%) were unchanged and 10 (17%) had progressed after 6 months. In 46% of the patients, the steroid dose could be more than halved. IgG, IgM and IgA decreased from normal levels prior to RTX therapy to below normal levels at 6 months in 2/22 (9%), 10/21 (48%), and 4/22 (18%) patients, respectively. Immunoglobulin deficiency or prolonged CD20 depletion was reported in eight patients after an observation period longer than 12 months. RTX therapy led to a perceivable reduction in disease activity. However, long-term immunological alterations may occur in more than 10% of the patients. Guidelines and protocols for off-label therapy are desirable to document reasonable follow-up data. Controlled prospective studies for RTX therapies in children with standardised therapeutic and diagnostic protocols are urgently needed.