Childhood Arthritis and Rheumatology Research Alliance consensus clinical treatment plans for juvenile dermatomyositis with skin predominant disease.

BACKGROUND: Juvenile dermatomyositis (JDM) is the most common form of the idiopathic inflammatory myopathies in children. A subset of children have the rash of JDM without significant weakness, and the optimal treatments for these children are unknown. The goal of this study was to describe the development of consensus clinical treatment plans (CTPs) for children with JDM who have active skin rashes, without significant muscle involvement, referred to as skin predominant JDM in this manuscript. METHODS: The Children's Arthritis and Rheumatology Research Alliance (CARRA) is a North American consortium of pediatric rheumatology health care providers. CARRA members collaborated to determine consensus on typical treatments for JDM patients with skin findings without significant weakness, to develop CTPs for this subgroup of patients. We used a combination of Delphi surveys and nominal group consensus meetings to develop these CTPs. RESULTS: Consensus was reached on patient characteristics and outcome assessment, and CTPs were developed and finalized for patients with skin predominant JDM. Treatment option A included hydroxychloroquine alone, Treatment option B included hydroxychloroquine and methotrexate, and Treatment option C included hydroxychloroquine, methotrexate and corticosteroids. CONCLUSIONS: Three CTPs were developed for use in children with skin predominant JDM, which reflect typical treatment approaches. These are not considered to be specific recommendations or standard of care. Using the CARRA network and prospective data collection, we will be able to apply statistical methods in the future to allow comparisons of JDM patients following these consensus treatment plans.

Structural mechanism for signal transduction in RXR nuclear receptor heterodimers.

A subset of nuclear receptors (NRs) function as obligate heterodimers with retinoid X receptor (RXR), allowing integration of ligand-dependent signals across the dimer interface via an unknown structural mechanism. Using nuclear magnetic resonance (NMR) spectroscopy, x-ray crystallography and hydrogen/deuterium exchange (HDX) mass spectrometry, here we show an allosteric mechanism through which RXR co-operates with a permissive dimer partner, peroxisome proliferator-activated receptor (PPAR)-γ, while rendered generally unresponsive by a non-permissive dimer partner, thyroid hormone (TR) receptor. Amino acid residues that mediate this allosteric mechanism comprise an evolutionarily conserved network discovered by statistical coupling analysis (SCA). This SCA network acts as a signalling rheostat to integrate signals between dimer partners, ligands and coregulator-binding sites, thereby affecting signal transmission in RXR heterodimers. These findings define rules guiding how NRs integrate two ligand-dependent signalling pathways into RXR heterodimer-specific responses.

Urine proteomics for discovery of improved diagnostic markers of Kawasaki disease.

Kawasaki disease (KD) is a systemic vasculitis of unknown etiology. Absence of definitive diagnostic markers limits the accuracy of clinical evaluations of suspected KD with significant increases in morbidity. In turn, incomplete understanding of its molecular pathogenesis hinders the identification of rational targets needed to improve therapy. We used high-accuracy mass spectrometry proteomics to analyse over 2000 unique proteins in clinical urine specimens of patients with KD. We discovered that urine proteomes of patients with KD, but not those with mimicking conditions, were enriched for markers of cellular injury such as filamin and talin, immune regulators such as complement regulator CSMD3, immune pattern recognition receptor muclin, and immune cytokine protease meprin A. Significant elevations of filamin C and meprin A were detected in both the serum and urine in two independent cohorts of patients with KD, comprised of a total of 236 patients. Meprin A and filamin C exhibited superior diagnostic performance as compared to currently used markers of disease in a blinded case-control study of 107 patients with suspected KD, with receiver operating characteristic areas under the curve of 0.98 (95% confidence intervals [CI] of 0.97-1 and 0.95-1, respectively). Notably, meprin A was enriched in the coronary artery lesions of a mouse model of KD. In all, urine proteome profiles revealed novel candidate molecular markers of KD, including filamin C and meprin A that exhibit excellent diagnostic performance. These disease markers may improve the diagnostic accuracy of clinical evaluations of children with suspected KD, lead to the identification of novel therapeutic targets, and allow the development of a biological classification of Kawasaki disease.

Critical care of the pediatric patient with rheumatic disease.

PURPOSE OF REVIEW: Extensive systemic illness and treatment with immunosuppressive agents often require patients with rheumatic diseases to be monitored or managed in the pediatric intensive care unit. Additionally, severe disease-specific manifestations of childhood rheumatic disorders present pediatric rheumatologists and critical care physicians with diagnostic and treatment challenges. Although mortality from rheumatic disease in children is rare, the most severe diseases, such as pediatric systemic lupus erythematosus and juvenile dermatomyositis, remain life-threatening. RECENT FINDINGS: Advances in therapy have reduced the incidence of severe complications of autoimmune and inflammatory diseases and have expanded treatment options. However, patients with active underlying rheumatic disease and secondary infection who are being treated with immunosuppressive agents are most at risk for poor outcomes. SUMMARY: Here we discuss the complications of childhood rheumatic conditions that necessitate critical intervention. We discuss how improved understanding of the cellular and molecular basis of disease pathogenesis holds the promise of more targeted therapy without the adverse effects of global immunosuppression.

Anakinra as first-line disease-modifying therapy in systemic juvenile idiopathic arthritis: report of forty-six patients from an international multicenter series.

OBJECTIVE: To examine the safety and efficacy of the interleukin-1 (IL-1) receptor antagonist anakinra as first-line therapy for systemic juvenile idiopathic arthritis (JIA). METHODS: Patients with systemic JIA receiving anakinra as part of initial disease-modifying antirheumatic drug (DMARD) therapy were identified from 11 centers in 4 countries. Medical records were abstracted using a standardized instrument, and resulting data were analyzed to characterize concomitant therapies, clinical course, adverse events, and predictors of outcome. RESULTS: Among 46 patients meeting inclusion criteria, anakinra monotherapy was used in 10 patients (22%), while 67% received corticosteroids and 33% received additional DMARDs. Outcomes were evaluated at a median followup interval of 14.5 months. Fever and rash resolved within 1 month in >95% of patients, while C-reactive protein and ferritin normalized within this interval in >80% of patients. Active arthritis persisted at 1 month in 39% of patients, at 3 months in 27%, and at >6 months of followup in 11%. Approximately 60% of patients, including 8 of 10 receiving anakinra monotherapy, attained a complete response without escalation of therapy. Disease characteristics and treatment were similar in partial and complete responders, except that partial responders were markedly younger at onset (median age 5.2 years versus 10.2 years; P = 0.004). Associated adverse events included documented bacterial infection in 2 patients and hepatitis in 1 patient. Tachyphylaxis was not observed. CONCLUSION: Anakinra as first-line therapy for systemic JIA was associated with rapid resolution of systemic symptoms and prevention of refractory arthritis in almost 90% of patients during the interval examined. These results justify further study of IL-1 inhibition as first-line, rather than rescue, therapy in systemic JIA.

Structural determinants of allosteric ligand activation in RXR heterodimers.

Allosteric communication underlies ligand-dependent transcriptional responses mediated by nuclear receptors. While studies have elucidated many of the components involved in this process, the energetic architecture within the receptor protein that mediates allostery remains unknown. Using a sequence-based method designed to detect coevolution of amino acids in a protein, termed the statistical coupling analysis (SCA), we identify a network of energetically coupled residues that link the functional surfaces of nuclear receptor ligand binding domains. Functional analysis of these predicted residues demonstrates their participation in an allosteric network that governs the ability of heterodimeric receptors to activate transcription in response to ligand binding by either partner. Interestingly, mutation of a single network residue can discriminate between receptor activation by endocrine, dietary, and synthetic agonists. These results reveal a structural network required for RXR heterodimer allosteric communication and suggest that the specificity of ligand response and permissivity coevolved to enable signal discrimination.

Structural determinants for vitamin D receptor response to endocrine and xenobiotic signals.

The vitamin D receptor (VDR), initially identified as a nuclear receptor for 1alpha,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3], regulates calcium metabolism, cellular proliferation and differentiation, immune responses, and other physiological processes. Recently, secondary bile acids such as lithocholic acid (LCA) were identified as endogenous VDR agonists. To identify structural determinants required for VDR activation by 1alpha,25(OH)2D3 and LCA, we generated VDR mutants predicted to modulate ligand response based on sequence homology to pregnane X receptor, another bile acid-responsive nuclear receptor. In both vitamin D response element activation and mammalian two-hybrid assays, we found that VDR-S278V is activated by 1alpha,25(OH)2D3 but not by LCA, whereas VDR-S237M can respond to LCA but not to 1alpha,25(OH)2D3. Competitive ligand binding analysis reveals that LCA, but not 1alpha,25(OH)2D3, effectively binds to VDR-S237M and both 1alpha,25(OH)2D3 and LCA bind to VDR-S278V. We propose a docking model for LCA binding to VDR that is supported by mutagenesis data. Comparative analysis of the VDR-LCA and VDR-1alpha,25(OH)2D3 structure-activity relationships should be useful in the development of bile acid-derived synthetic VDR ligands that selectively target VDR function in cancer and immune disorders without inducing adverse hypercalcemic effects.

The generation of monoclonal antibodies against human peroxisome proliferator-activated receptors (PPARs).

Monoclonal antibodies (Mabs) are valuable reagents for the purification, characterization and immunolocalization of proteins. In this study, we raised Mabs against human peroxisome proliferator-activated receptors (PPARs) using baculovirus particles displaying surface glycoprotein gp64-fusion proteins as the immunizing agent. In this system, to display fusion proteins on the viral surface, the amino terminal sequences of human PPARd and PPARg2 are inserted in-frame between the signal sequence and the mature domain of the gp64 nucleotide sequence.Mabs were raised by immunization with whole virus without a purification of the target antigens. The Mabs generated by this novel method were shown to recognize not only the gp64-PPARs fusion protein, but also mature, expressed proteins by a wide variety of techniques, including immunohistochemistry, immunoblotting, and electrophoretic mobility shift assays (EMSAs). Transfection of the transfer vector containing a nucleotide sequence encoding less than 30 amino acids along with linearized baculovirus DNA allows for the production of a high affinity antibody against the corresponding mature form. This method is of potential utility in that it allows the production of valuable antibodies without the requirement of a protein purification step.