AB0552 CHARACTERISTICS OF MYOSITIS SPECTRUM DISEASE - RHEUMATOID ARTHRITIS OVERLAP CASES IN A HUNGARIAN COHORT

Background:

Overlap syndromes are autoimmune disorders in which classification criteria of at least two connective tissue diseases (CTDs) are fulfilled. The Division of Clinical Immunology in Debrecen, Hungary oversees patients with idiopathic inflammatory myopathies (IIMs) since the 1980’s.

Objectives:

In a work called The Myositis Antibody Research Project, which is coordinated together with the Bath Institute for Rheumatic Diseases (UK), authors investigated 330 patients with myositis, all treated in this Hungarian center.

Methods:

The aim of this retrospective study was to investigate the frequency, clinical and serological parameters and therapeutic options in myositis – rheumatoid arthritis overlap cases in this group of 330 patients.

Results:

The frequency of overlap cases, as seen in literature, was 13.64%. The importance of myositis-associated antibodies (MAAs) can be seen on this results: 44.44% of overlap patients, while only 7.02% of not overlap patients were MAA positive. Out of our 45 overlap patients twenty-seven myositis - RA overlap patients could be identified. Among these 27 patients the women:men ratio was 12.5:1, PM:DM ratio was 2.375:1. Muscle weakness and sceletal involvement was present in every patient, myalgia in 77.78% and Raynaud’s phenomenon in 48.15% of the patients; general symptoms during disease relapse (fatigue, weight loss, fever) were present in 59.26%, 18.52% and 14.82%, respectively. Ten cases had seropositive rheumatoid arthritis, with high titer of rheumatoid factor. Authors underline the importance of lung involvement as internal organ manifestation: 8 patients had anti-synthetase antibodies (six anti-Jo-1, one anti-PL-7 and one anti-PL-12). In anti-PL-7 and anti-PL-12 positive patients interstitial lung disease (ILD) appeared some years before myositis and early agressive management of ILD resulted in fast remission of muscle weakness. Anti-Mi-2 and anti-SRP could be detected in two patients. Most frequent used disease modifying antirheumatic drugs were cyclophosphamide, methotrexate and cyclosporine, 19 patients received DMARD combination therapy. Biological therapy was used in 3 patients, intravenous or subcutaneous immuneglobulin in 4 patients and one patient with RA – myositis – antiphospholipid syndrome died because of asipartion pneumonia.

Conclusion:

Authors conclude that it is really challenging to treat these overlap cases: they form a very heterogenous group of patients and management has to be personalized.

Disclosure of Interests:

None declared

Autoantibodies to a 140-kd protein in juvenile dermatomyositis are associated with calcinosis

OBJECTIVE

The identification of novel autoantibodies in juvenile dermatomyositis (DM) may have etiologic and clinical implications. The aim of this study was to describe autoantibodies to a 140-kd protein in children recruited to the Juvenile DM National Registry and Repository for UK and Ireland.

METHODS

Clinical data and sera were collected from children with juvenile myositis. Sera that recognized a 140-kd protein by immunoprecipitation were identified. The identity of the p140 autoantigen was investigated by immunoprecipitation/immunodepletion, using commercial monoclonal antibodies to NXP-2, reference anti-p140, and anti-p155/140, the other autoantibody recently described in juvenile DM. DNA samples from 100 Caucasian children with myositis were genotyped for HLA class II haplotype associations and compared with those from 864 randomly selected UK Caucasian control subjects.

RESULTS

Sera from 37 (23%) of 162 patients with juvenile myositis were positive for anti-p140 autoantibodies, which were detected exclusively in patients with juvenile DM and not in patients with juvenile DM-overlap syndrome or control subjects. No anti-p140 antibody-positive patients were positive for other recognized autoantibodies. Immunodepletion suggested that the identity of p140 was consistent with NXP-2 (the previously identified MJ autoantigen). In children with anti-p140 antibodies, the association with calcinosis was significant compared with the rest of the cohort (corrected P < 0.005, odds ratio 7.0, 95% confidence interval 3.0-16.1). The clinical features of patients with anti-p140 autoantibodies were different from those of children with anti-p155/140 autoantibodies. The presence of HLA-DRB1*08 was a possible risk factor for anti-p140 autoantibody positivity.

CONCLUSION

This study has established that anti-p140 autoantibodies represent a major autoantibody subset in juvenile DM. This specificity may identify a further immunogenetic and clinical phenotype within the juvenile myositis spectrum that includes an association with calcinosis.

Evidence for a role of ganglioside GM1 in antigen presentation: binding enhances presentation of Escherichia coli enterotoxin B subunit (EtxB) to CD4(+) T cells

Successful antigen presentation by antigen-presenting cells is governed by a number of factors including the efficiency of antigen capture by cell-surface receptors, targeting to compartments of antigen processing, surface expression of MHC II-peptide complexes and presence of co-stimulatory signals. Ganglioside GM1 is an important component of membrane glycosphingolipids, and has been implicated in cell differentiation, apoptosis and signal transduction pathways. Using the B subunit of Escherichia coli enterotoxin (EtxB), a potent immunogen that binds GM1 with high affinity, and a non-binding mutant of EtxB, EtxB(G33D), we demonstrate that GM1 is intimately involved in several aspects of antigen presentation. Thus, GM1-mediated presentation of EtxB by B cells and CD11c(+) dendritic cells (DC) significantly enhanced the proliferation and cytokine expression of EtxB-specific CD4(+) T cells. Investigation regarding potential mechanisms revealed that EtxB binding directly augments the expression of MHC class II on B cells, and fractionation of B cells demonstrated that EtxB binding to GM1 results in rapid internalization and targeting to class II-rich compartments. GM1-mediated uptake of antigens and access to class II compartments in B cells can be exploited to significantly enhance the presentation of ovalbumin-conjugated to EtxB. These results demonstrate that GM1 can play an important role in antigen presentation via the MHC II pathway.