The autoimmune spectrum of myasthenia gravis: a Swedish population-based study

OBJECTIVES

To determine the prevalence of myasthenia gravis (MG) and the rate of concurrent autoimmune diseases in patients with MG.

DESIGN AND SETTING

Using the Swedish health and population registers, during the period 2005-2010, we conducted a nested case-control study of patients with MG (n = 2045) with five age- and sex-matched population-based controls per case. Register-based MG diagnosis was validated against the Stockholm MG Cohort. Similar nested case-control studies were conducted in patients with multiple sclerosis (MS), as a neuroinflammatory disease control, and siblings of patients with MG.

MAIN OUTCOME MEASURE

Odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated as a measure of the association between MG and other autoimmune diseases.

RESULTS

The prevalence of MG was 24.8/100,000, and patients with MG had an increased risk of another autoimmune disease compared to controls (22.0% vs. 8.9%; OR: 2.82, 95% CI: 2.49-3.20); this risk was stronger amongst younger persons and women. Polymyositis/dermatomyositis, systemic lupus erythematosus and Addison's disease, three conditions regulated by the HLA-B8-DR3 haplotype, were most strongly associated with MG, especially early-onset disease. HLA typing in the Stockholm MG Cohort showed that early-onset MG was indeed dominated by HLA-B8-DR3. The risk of another autoimmune disease was increased in both patients with MS and siblings of patients with MG, compared to their respective controls, but to a lesser extent than in patients with MG.

CONCLUSIONS

Our results suggest that MG shares risk factors with other autoimmune diseases, to a greater degree than MS, with a particular role of the HLA-B8-DR3 haplotype, especially amongst younger and female patients.

Differences and similarities in rheumatology specialty training programmes across European countries

OBJECTIVES

To analyse the similarities and discrepancies between the official rheumatology specialty training programmes across Europe.

METHODS

A steering committee defined the main aspects of training to be assessed. In 2013, the rheumatology official training programmes were reviewed for each of the European League Against Rheumatism (EULAR) countries and two local physicians independently extracted data on the structure of training, included competencies and assessments performed. Analyses were descriptive.

RESULTS

41 of the 45 EULAR countries currently provide specialist training in rheumatology; in the remaining four rheumatologists are trained abroad. 36 (88%) had a single national curriculum, one country had two national curricula and four had only local or university-specific curricula. The mean length of training programmes in rheumatology was 45 (SD 19) months, ranging between 3 and 72 months. General internal medicine training was mandatory in 40 (98%) countries, and was performed prior to and/or during the rheumatology training programme (mean length: 33 (19) months). 33 (80%) countries had a formal final examination.

CONCLUSIONS

Most European countries provide training in rheumatology, but the length, structure, contents and assessments of these training programmes are quite heterogeneous. In order to promote excellence in standards of care and to support physicians' mobility, a certain degree of harmonisation should be encouraged.

Disease specificity of autoantibodies to cytosolic 5'-nucleotidase 1A in sporadic inclusion body myositis versus known autoimmune diseases

OBJECTIVES

The diagnosis of inclusion body myositis (IBM) can be challenging as it can be difficult to clinically distinguish from other forms of myositis, particularly polymyositis (PM). Recent studies have shown frequent presence of autoantibodies directed against cytosolic 5'-nucleotidase 1A (cN-1A) in patients with IBM. We therefore, examined the autoantigenicity and disease specificity of major epitopes of cN-1A in patients with sporadic IBM compared with healthy and disease controls.

METHODS

Serum samples obtained from patients with IBM (n=238), PM and dermatomyositis (DM) (n=185), other autoimmune diseases (n=246), other neuromuscular diseases (n=93) and healthy controls (n=35) were analysed for the presence of autoantibodies using immunodominant cN-1A peptide ELISAs.

RESULTS

Autoantibodies directed against major epitopes of cN-1A were frequent in patients with IBM (37%) but not in PM, DM or non-autoimmune neuromuscular diseases (<5%). Anti-cN-1A reactivity was also observed in some other autoimmune diseases, particularly Sjögren's syndrome (SjS; 36%) and systemic lupus erythematosus (SLE; 20%).

CONCLUSIONS

In summary, we found frequent anti-cN-1A autoantibodies in sera from patients with IBM. Heterogeneity in reactivity with the three immunodominant epitopes indicates that serological assays should not be limited to a distinct epitope region. The similar reactivities observed for SjS and SLE demonstrate the need to further investigate whether distinct IBM-specific epitopes exist.

Determination of the minimal clinically important difference for seven measures of fatigue in Swedish patients with systemic lupus erythematosus

OBJECTIVE

To estimate the minimal clinically important difference (MCID) in seven self-administered measures assessing fatigue in Swedish patients with systemic lupus erythematosus (SLE).

METHOD

The participants (n = 51, women 98%, age 52.8 ± 12.1 years, disease duration 18.7 ± 13.6 years) met in groups of six to nine persons. After completing seven fatigue questionnaires [the Fatigue Severity Scale (FSS); the Multidimensional Assessment of Fatigue (MAF) scale; the 20-item Multidimensional Fatigue Inventory (MFI); the Chalder Fatigue Scale (CFS); the Short Form-36 Vitality subscale (VT); the Functional Assessment of Chronic Illness Therapy - Fatigue (FACIT-F) scale; and the Numeric Rating Scale (NRS)], each respondent had a minimum of five face-to-face discussions, followed by an individual comparative assessment of their own level of fatigue (seven-grade scale). This method resulted in 260 contrasting assessments; MCIDs were first calculated using the paired differences and then established by a regression approach. Patients were asked to comment on their experience with the questionnaires and whether they captured their fatigue adequately.

RESULTS

The paired approach (using 'little more fatigue' as an anchor for MCID during the face-to-face comparative assessments) provided estimates of 4.6-17.0; the regression approach provided estimates of 4.3-10.8. Estimates using the regression approach were consistently lower than those using the paired model. The MCID estimates were least favourable and fewer respondents supported the use of the NRS compared to the other self-reported questionnaires.

CONCLUSIONS

All seven instruments detect MCIDs for fatigue in Swedish patients with SLE. However, the single-question measure was not supported by the MCID estimates or by comments from the respondents.

An outsourced health-enhancing physical activity programme for people with rheumatoid arthritis: exploration of adherence and response

OBJECTIVES

The aims of this study were to document adherence to and changes in health-enhancing physical activity (HEPA) levels and self-reported and assessed functioning and to explore aspects of adherence and response during the first year of an outsourced 2-year HEPA programme in people with RA.

METHODS

Two-hundred and twenty patients participated in this observational cohort study, which included daily physical activity, twice-weekly circuit training and biweekly support group meetings. Self-reported data included current (past week) and maintained (past 6 months) HEPA levels, sociodemographics and disease-related and psychosocial factors. Tests of aerobic capacity and muscle function were performed and anthropometric data were collected.

RESULTS

Eighty-eight per cent of the participants completed 1 year assessments. Self-reported current and maintained HEPA increased. General health perception and a number of other self-reported disease-related and psychosocial factors improved, while exercise self-efficacy declined. Aerobic capacity, timed standing and grip strength improved and waist circumference decreased. The mean number of circuit training sessions performed was 48, the mean number of days with HEPA was 189 and the mean number of support group meetings attended was 9. Better adherence to circuit training improved general health, and better adherence to group meetings improved timed standing. Exercise self-efficacy improved among those adhering more to circuit training or support group meetings.

CONCLUSION

The outsourced HEPA programme had high retention and reasonable adherence. A number of health outcomes improved. Relationships between adherence to the programme components and response were not clear-cut and need further attention.

TRIAL REGISTRATION

ISRCTN register; http://www.controlled-trials.com. Trial registration number ISRCTN25539102.

Effects of adalimumab treatment on endothelial cell activation markers in the skeletal muscle of patients with rheumatoid arthritis

OBJECTIVES

Patients with rheumatoid arthritis (RA), particularly those with severe disease, have increased risk of cardiovascular disease (CVD). Previous studies suggest that endothelial cell activation may contribute to this co-morbidity, and that treatment with tumour necrosis factor (TNF) inhibitors could reduce the risk of CVD in these patients. The aim of this study was to investigate endothelial cell activation markers in muscle tissue of patients after adalimumab treatment.

METHODS

Patients with active RA who started treatment with adalimumab 40 mg every two weeks were included. Muscle biopsies taken before and 3 months after start of treatment were available from 11 patients (9 females, mean age 54.2 years, median disease duration 6.5 years, 91% anti-CCP positive, 7 on methotrexate [median dose 20 mg/week]). None of the patients had clinical signs of myopathy. IL-1α and HLA-DQ were investigated by immunohistochemistry. Quantification was performed by computer assisted image analysis.

RESULTS

Disease activity, measured by DAS28 decreased (mean 5.5 vs. 4.1; p=0018). A good or moderate EULAR response was seen in 6/11 patients. HLA-DQ was mainly expressed in endothelial cells in capillaries, whereas IL-1α was mainly seen in larger vessels. HLA-DQ expression decreased significantly after treatment (p=0.041). There was a similar trend for IL-1α, in particlar in EULAR good/moderate responders.

CONCLUSIONS

Adalimumab treatment was associated with decreased expression of endothelial markers previously associated with severe systemic inflammation in RA. Our findings indicate a reduced endothelial activation in patients treated with anti-TNF drugs, which might contribute to a lower risk of cardiovascular co-morbidity.

Expression of BAFF receptors in muscle tissue of myositis patients with anti-Jo-1 or anti-Ro52/anti-Ro60 autoantibodies

INTRODUCTION

Anti-Jo-1 and anti-Ro52 autoantibodies are common in patients with myositis, but the mechanisms behind their production are not known. Survival of autoantibody-producing cells is dependent on B-cell-activating factor of the tumour necrosis factor family (BAFF). BAFF levels are elevated in serum of anti-Jo-1-positive myositis patients and are influenced by type-I interferon (IFN). IFN-producing cells and BAFF mRNA expression are present in myositis muscle. We investigated expression of the receptors for BAFF in muscle tissue in relation to anti-Jo-1 and anti-Ro52/anti-Ro60 autoantibodies and type-I IFN markers.

METHODS

Muscle biopsies from 23 patients with myositis selected based on autoantibody profile and 7 healthy controls were investigated for expression of BAFF receptor (BAFF-R), B-cell maturation antigen (BCMA) and transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI). Nineteen samples were assessed for plasma (CD138) and B-cell (CD19) markers. The numbers of positive cells per area were compared with the expression of plasmacytoid dendritic cell (pDC) marker blood dendritic cell antigen-2 (BDCA-2) and IFNα/β-inducible myxovirus resistance-1 protein (MX-1).

RESULTS

BAFF-R, BCMA and TACI were expressed in five, seven and seven patients, respectively, and more frequently in anti-Jo-1-positive and/or anti-Ro52/anti-Ro60-positive patients compared to controls and to patients without these autoantibodies (P = BAFF-R: 0.007, BCMA: 0.03 and TACI: 0.07). A local association of receptors with B and plasma cells was confirmed by confocal microscopy. The numbers of CD138-positive and BCMA-positive cells were correlated (r = 0.79; P = 0.001). Expression of BDCA-2 correlated with numbers of CD138-positive cells and marginally with BCMA-positive cells (r = 0.54 and 0.42, respectively; P = 0.04 and 0.06, respectively). There was a borderline correlation between the numbers of positively stained TACI cells and MX-1 areas (r = 0.38, P = 0.08).

CONCLUSIONS

The expression pattern of receptors for BAFF on B and plasma cells in muscle suggests a local role for BAFF in autoantibody production in muscle tissues of patients with myositis who have anti-Jo-1 or anti-Ro52/anti-Ro60 autoantibodies. BAFF production could be influenced by type-I IFN produced by pDCs. Thus, B-cell-related molecular pathways may participate in the pathogenesis of myositis in this subset of patients.

Nitrosative modifications of the Ca2+ release complex and actin underlie arthritis-induced muscle weakness

OBJECTIVE

Skeletal muscle weakness is a prominent clinical feature in patients with rheumatoid arthritis (RA), but the underlying mechanism(s) is unknown. Here we investigate the mechanisms behind arthritis-induced skeletal muscle weakness with special focus on the role of nitrosative stress on intracellular Ca(2+) handling and specific force production.

METHODS

Nitric oxide synthase (NOS) expression, degree of nitrosative stress and composition of the major intracellular Ca(2+) release channel (ryanodine receptor 1, RyR1) complex were measured in muscle. Changes in cytosolic free Ca(2+) concentration ([Ca(2+)]i) and force production were assessed in single-muscle fibres and isolated myofibrils using atomic force cantilevers.

RESULTS

The total neuronal NOS (nNOS) levels were increased in muscles both from collagen-induced arthritis (CIA) mice and patients with RA. The nNOS associated with RyR1 was increased and accompanied by increased [Ca(2+)]i during contractions of muscles from CIA mice. A marker of peroxynitrite-derived nitrosative stress (3-nitrotyrosine, 3-NT) was increased on the RyR1 complex and on actin of muscles from CIA mice. Despite increased [Ca(2+)]i, individual CIA muscle fibres were weaker than in healthy controls, that is, force per cross-sectional area was decreased. Furthermore, force and kinetics were impaired in CIA myofibrils, hence actin and myosin showed decreased ability to interact, which could be a result of increased 3-NT content on actin.

CONCLUSIONS

Arthritis-induced muscle weakness is linked to nitrosative modifications of the RyR1 protein complex and actin, which are driven by increased nNOS associated with RyR1 and progressively increasing Ca(2+) activation.

Resistive Home Exercise in Patients with Recent-onset Polymyositis and Dermatomyositis — A Randomized Controlled Single-blinded Study with a 2-year Followup

Objective.

To evaluate the outcome of resistive home exercise and its possible longterm influence on health, disability, and disease activity in patients with active polymyositis (PM) or dermatomyositis (DM).

Methods.

Nineteen patients with recent-onset PM/DM were included after introduction of high-dose prednisolone. They were assessed by independent assessors as to perceived health, muscle performance, aerobic capacity, and serum creatine phosphokinase (CPK) at baseline and after 24 weeks, including repeated muscle biopsies at 24 weeks (single-blinded randomized controlled study), and in an open-label followup at 52, 78, and 104 weeks. Patients were randomized to 12 weeks, 5 days/week resistive home exercise with telephone support and encouragement for another 12 weeks of twice-a-week home or gym exercise (EG, n = 10) or to 24 weeks, 5 days/week range of motion exercise (CG, n = 9). Patients in the CG group without inflammatory infiltrates in muscle biopsies at 24 weeks were invited to the 12-week resistive home exercises.

Results.

At baseline, the EG had poorer perceived health, but otherwise the groups were comparable. At 24 weeks, both groups improved in muscle performance and aerobic capacity (p < 0.001 to < 0.05) with no signs of increased inflammation assessed by CPK levels or muscle biopsies. Both groups improved in muscle performance and aerobic capacity up to 52 weeks (p < 0.05) lasting to 104 weeks in the EG (p < 0.05) and presented minor improvements in perceived health.

Conclusion.

Our study supports the safety of resistive exercise in patients with active PM/DM but did not reveal any between-group differences in exercise effects. An individually adapted physical therapist–supervised home exercise program might be recommended in early active PM/DM, with regular evaluation of muscle performance and health.

Elevated expression of prostaglandin E2 synthetic pathway in skeletal muscle of prior polio patients

OBJECTIVE

The aim of this study was to investigate signs of inflammation in muscle of patients with prior polio, since the main symptoms in these patients are muscle pain, weakness and fatigue. In the context of pain and inflammation, the prostaglandin E2 pathway is of interest. Prostaglandin E2 has many biological actions and is a mediator of inflammation and pain.

PATIENTS AND METHODS

Skeletal muscle biopsies from 8 patients with prior polio and post-polio symptoms, presenting with pain and muscular weakness, and from 6 healthy controls were studied. Immunohistochemistry, conventional microscopy, and computerized image analysis were performed.

RESULTS

There was statistically significant higher expression of enzymes of the prostaglandin E2 synthetic pathway, in muscle from patients, compared with controls. Expression of prostaglandin enzymes was mainly in scattered cells and blood vessels, and may indicate an inflammatory process of the muscle, which could be secondary to systemic inflammation.

CONCLUSION

This data may indicate an inflammatory process in muscle of prior polio patients. Up-regulation of the prostaglandin E2 pathway reveals a potential background to the pain experienced by these patients, and may provide opportunities for directed pharmacological and physical therapies, which could lead to better outcomes of rehabilitation interventions.

Patients with regular physical activity before onset of rheumatoid arthritis present with milder disease

OBJECTIVES

Physical activity has been shown to decrease inflammatory markers; here we investigate the effect on the clinical presentation of rheumatoid arthritis (RA).

METHODS

We used the cases from the population-based EIRA study (N=617), followed in the Swedish Rheumatology Quality Register, calculating the odds of having above median level of 28-joint disease activity score (DAS28), physician assessment, pain (visual-analogue scale (VAS), VAS-pain) and activity limitation (health assessment questionnaire (HAQ)) at diagnosis, as an effect of physical activity 5 years before diagnosis, investigated both in categories and dichotomised.

RESULTS

Dose-response relationships were seen for all measures; the higher the level of physical activity, the lower the likelihood of having outcome measure above median. Further, regular physical activity associated with 42% reduced odds of having DAS28 above median (OR=0.58 (95% CI 0.42 to 0.81)). Effects were similar for VAS-pain (OR=0.62 (95%CI 0.45 to 0.86)) and physician assessment (OR=0.67 (95%CI 0.47 to 0.95)) but not for HAQ. Statistically significant effects were also found both for the combined objective components and the combined subjective components of DAS28.

CONCLUSIONS

Physically active individuals seem to present with milder RA, which adds to the evidence of beneficial effects of physical activity on inflammatory diseases. The observation should be important for both health professionals and individuals seeking to reduce their risk.

Hand exercise intervention in patients with polymyositis and dermatomyositis: a pilot study

OBJECTIVE

The aim of the present study was to develop a 12-week hand exercise intervention for patients with polymyositis (PM) and dermatomyositis (DM) and evaluate adherence, patients' opinions of the programme design and overall feasibility, and the effect on hand function and activity limitation after the intervention.

METHOD

A pilot hand exercise intervention was conducted on a convenience sample of 15 patients with reduced handgrip strength and established, inactive PM and DM. Acceptable adherence was set at 75%. The programme was evaluated based on patients' opinions regarding exertion, the movements involved and overall feasibility. Hand- and pinch-grip strength, grip ability, dexterity and activity limitation were assessed.

RESULTS

Eleven of 15 patients completed the intervention, with acceptable adherence of 78-100%. Measures of handgrip strength, dexterity and activity limitation were reduced at baseline compared with normative data from the literature. Throughout the intervention, rates of perceived exertion were scored between 'moderate' and 'fairly strong'. Finger abduction and adduction were excluded from the hand exercise programme because they were not feasible to perform. Repetitions of the exercise increased gradually to a maximum of 30 per movement. Patients regarded this as too time-consuming and suggested ten repetitions daily or 10-20 repetitions 2-4 times per week. There were some individual, clinically meaningful improvements in hand function and activity limitation. A comparison between baseline and after the intervention showed that the three-jaw (tripod) pinch-grip strength (left hand) had increased (p < 0.007; z = -2.7).

CONCLUSION

A hand exercise programme was found to be feasible to perform by patients with established PM or DM. The effect was limited, with few individual improvements in hand function and activity limitation, indicating a need to increase the resistance in the movements and to limit the duration of each exercise session.

Patient-reported outcomes and adult patients' disease experience in the idiopathic inflammatory myopathies. report from the OMERACT 11 Myositis Special Interest Group

The newly formed Outcome Measures in Rheumatology (OMERACT) Myositis Special Interest Group (SIG) was established to examine patient-reported outcome measures (PROM) in myositis. At OMERACT 11, a literature review of PROM used in the idiopathic inflammatory myopathies (IIM) and other neuromuscular conditions was presented. The group examined in more detail 2 PROM more extensively evaluated in patients with IIM, the Myositis Activities Profile, and the McMaster-Toronto Arthritis Patient Preference Disability Questionnaire, through the OMERACT filter of truth, discrimination, and feasibility. Preliminary results from a qualitative study of patients with myositis regarding their symptoms were discussed that emphasized the range of symptoms experienced: pain, physical tightness/stiffness, fatigue, disease effect on emotional life and relationships, and treatment-related side effects. Following discussion of these results and following additional discussions since OMERACT 11, a research agenda was developed. The next step in evaluating PROM in IIM will require additional focus groups with a spectrum of patients with different myositis disease phenotypes and manifestations across a range of disease activity, and from multiple international settings. The group will initially focus on dermatomyositis and polymyositis in adults. Qualitative analysis will facilitate the identification of commonalities and divergent patient-relevant aspects of disease, insights that are critical given the heterogeneous manifestations of these diseases. Based on these qualitative studies, existing myositis PROM can be examined to more thoroughly assess content validity, and will be important to identify gaps in domain measurement that will be required to develop a preliminary core set of patient-relevant domains for IIM.

Genome-wide association study of dermatomyositis reveals genetic overlap with other autoimmune disorders

OBJECTIVE

To identify new genetic associations with juvenile and adult dermatomyositis (DM).

METHODS

We performed a genome-wide association study (GWAS) of adult and juvenile DM patients of European ancestry (n = 1,178) and controls (n = 4,724). To assess genetic overlap with other autoimmune disorders, we examined whether 141 single-nucleotide polymorphisms (SNPs) outside the major histocompatibility complex (MHC) locus, and previously associated with autoimmune diseases, predispose to DM.

RESULTS

Compared to controls, patients with DM had a strong signal in the MHC region consisting of GWAS-level significance (P < 5 × 10(-8)) at 80 genotyped SNPs. An analysis of 141 non-MHC SNPs previously associated with autoimmune diseases showed that 3 SNPs linked with 3 genes were associated with DM, with a false discovery rate (FDR) of <0.05. These genes were phospholipase C-like 1 (PLCL1; rs6738825, FDR = 0.00089), B lymphoid tyrosine kinase (BLK; rs2736340, FDR = 0.0031), and chemokine (C-C motif) ligand 21 (CCL21; rs951005, FDR = 0.0076). None of these genes was previously reported to be associated with DM.

CONCLUSION

Our findings confirm the MHC as the major genetic region associated with DM and indicate that DM shares non-MHC genetic features with other autoimmune diseases, suggesting the presence of additional novel risk loci. This first identification of autoimmune disease genetic predispositions shared with DM may lead to enhanced understanding of pathogenesis and novel diagnostic and therapeutic approaches.

Validation of a score tool for measurement of histological severity in juvenile dermatomyositis and association with clinical severity of disease

Objectives

To study muscle biopsy tissue from patients with juvenile dermatomyositis (JDM) in order to test the reliability of a score tool designed to quantify the severity of histological abnormalities when applied to biceps humeri in addition to quadriceps femoris. Additionally, to evaluate whether elements of the tool correlate with clinical measures of disease severity.

Methods

55 patients with JDM with muscle biopsy tissue and clinical data available were included. Biopsy samples (33 quadriceps, 22 biceps) were prepared and stained using standardised protocols. A Latin square design was used by the International Juvenile Dermatomyositis Biopsy Consensus Group to score cases using our previously published score tool. Reliability was assessed by intraclass correlation coefficient (ICC) and scorer agreement (α) by assessing variation in scorers’ ratings. Scores from the most reliable tool items correlated with clinical measures of disease activity at the time of biopsy.

Results

Inter- and intraobserver agreement was good or high for many tool items, including overall assessment of severity using a Visual Analogue Scale. The tool functioned equally well on biceps and quadriceps samples. A modified tool using the most reliable score items showed good correlation with measures of disease activity.

Conclusions

The JDM biopsy score tool has high inter- and intraobserver agreement and can be used on both biceps and quadriceps muscle tissue. Importantly, the modified tool correlates well with clinical measures of disease activity. We propose that standardised assessment of muscle biopsy tissue should be considered in diagnostic investigation and clinical trials in JDM.

Immune mechanisms in polymyositis and dermatomyositis and potential targets for therapy

PM and DM are characterized clinically by weakness and low endurance of skeletal muscle. Other organs are frequently involved, suggesting that idiopathic inflammatory myopathies (IIMs) are systemic inflammatory diseases. Involvement of immune mechanisms in IIMs is supported by the presence of T cells, macrophages and dendritic cells in muscle tissue, by the presence of autoantibodies and by HLA-DR being a strong genetic risk factor. T cells may have direct and indirect toxic effects on muscle fibres, causing muscle fibre necrosis and muscle weakness, but the target of the immune reaction is not known. A newly identified T cell subset, CD28(null) T cells, may have cytotoxic effects in the CD4(+) and CD8(+) T cell phenotype. These cells are apoptosis resistant and may contribute to treatment resistance. Several myositis-specific autoantibodies have been identified, but they are all directed against ubiquitously expressed autoantigens and the specificity of the T cell reactivity is not known. These autoantibodies are associated with distinct clinical phenotypes and some with distinct molecular pathways; e.g. sera from patients with anti-Jo-1 autoantibodies may activate the type I IFN system and these sera also contain high levels of B cell activating factor compared with other IIM subsets. The characterization of patients into subgroups based on autoantibody profiles seems to be a promising way to learn more about the specificities of the immune reactions. Careful phenotyping of infiltrating immune cells in muscle tissue before and after specific therapies and relating the molecular findings to clinical outcome measures may be another way to improve knowledge on specific immune mechanism in IIMs. Such information will be important for the development of new therapies.

Autoantibodies to cytosolic 5'-nucleotidase 1A in inclusion body myositis

OBJECTIVE

Sporadic inclusion body myositis (sIBM) is an inflammatory myopathy characterized by both degenerative and autoimmune features. In contrast to other inflammatory myopathies, myositis-specific autoantibodies had not been found in sIBM patients until recently. We used human skeletal muscle extracts as a source of antigens to detect autoantibodies in sIBM and to characterize the corresponding antigen.

METHODS

Autoantibodies to skeletal muscle antigens were detected by immunoblotting. The target antigen was immunoaffinity-purified from skeletal muscle extracts and characterized by mass spectrometry. A cDNA encoding this protein was cloned and expressed in vitro, and its recognition by patient sera was analyzed in an immunoprecipitation assay. Epitopes were mapped using microarrays of overlapping peptides.

RESULTS

An Mr 44,000 polypeptide (Mup44) was frequently targeted by sIBM autoantibodies. The target protein was purified, and subsequent mass spectrometry analysis revealed that Mup44 is the cytosolic 5'-nucleotidase 1A (cN1A). By immunoprecipitation of recombinant cN1A, high concentrations of anti-Mup44 autoantibodies were detected in 33% of sIBM patient sera, whereas their prevalence in dermatomyositis, polymyositis, and other neuromuscular disorders appeared to be rare (4.2%, 4.5%, and 3.2%, respectively). Low concentrations of anti-Mup44 antibodies were found in myositis as well as other neuromuscular disorders, but not in healthy controls. Three major autoepitope regions of cN1A were mapped by using microarrays containing a set of overlapping peptides covering the complete cN1A amino acid sequence.

INTERPRETATION

Anti-Mup44 autoantibodies, which are targeted to cN1A, represent the first serological biomarker for sIBM and may facilitate the diagnosis of this type of myositis.

The role of TRAIL in mediating autophagy in myositis skeletal muscle: a potential nonimmune mechanism of muscle damage

OBJECTIVE

Multinucleated cells are relatively resistant to classic apoptosis, and the factors initiating cell death and damage in myositis are not well defined. We hypothesized that nonimmune autophagic cell death may play a role in muscle fiber damage. Recent reports indicate that TRAIL may induce both NF-κB activation and autophagic cell death in other systems. We undertook this study to investigate the role of TRAIL in cell death and pathogenesis in vitro and in vivo, using myositis muscle tissues from humans and mice.

METHODS

Gene expression profiling was performed in myositis patient and control muscle specimens. Immunohistochemistry analysis was performed to confirm the gene array findings. We also analyzed TRAIL-induced cell death (apoptosis and autophagy) and NF-κB activation in vitro in cultured cells.

RESULTS

TRAIL was expressed predominantly in myositis muscle fibers, but not in biopsy specimens from normal or other dystrophic-diseased muscle. Autophagy markers were up-regulated in humans with myositis and in mouse models of myositis. TRAIL expression was restricted to regenerating/atrophic areas of muscle fascicles, blood vessels, and infiltrating lymphocytes. TRAIL induced NF-κB activation and IκB degradation in cultured cells that are resistant to TRAIL-induced apoptosis but that undergo autophagic cell death.

CONCLUSION

Our data demonstrate that TRAIL is expressed in myositis muscle and may mediate both activation of NF-κB and autophagic cell death in myositis. Thus, this nonimmune pathway may be an attractive target for therapeutic intervention in myositis.

Autoantibodies produced at the site of tissue damage provide evidence of humoral autoimmunity in inclusion body myositis

Inclusion body myositis (IBM) belongs to a group of muscle diseases known as the inflammatory myopathies. The presence of antibody-secreting plasma cells in IBM muscle implicates the humoral immune response in this disease. However, whether the humoral immune response actively contributes to IBM pathology has not been established. We sought to investigate whether the humoral immune response in IBM both in the periphery and at the site of tissue damage was directed towards self-antigens. Peripheral autoantibodies present in IBM serum but not control serum recognized self-antigens in both muscle tissue and human-derived cell lines. To study the humoral immune response at the site of tissue damage in IBM patients, we isolated single plasma cells directly from IBM-derived muscle tissue sections and from these cells, reconstructed a series of recombinant immunoglobulins (rIgG). These rIgG, each representing a single muscle-associated plasma cell, were examined for reactivity to self-antigens. Both, flow cytometry and immunoblotting revealed that these rIgG recognized antigens expressed by cell lines and in muscle tissue homogenates. Using a mass spectrometry-based approach, Desmin, a major intermediate filament protein, expressed abundantly in muscle tissue, was identified as the target of one IBM muscle-derived rIgG. Collectively, these data support the view that IBM includes a humoral immune response in both the periphery and at the site of tissue damage that is directed towards self-antigens.

Anti-PL-7 (anti-threonyl-tRNA synthetase) antisynthetase syndrome: clinical manifestations in a series of patients from a European multicenter study (EUMYONET) and review of the literature

Autoantibodies against several aminoacyl-transfer-RNA synthetases have been described in patients with myositis; anti-threonyl-tRNA synthetase (anti-PL-7) is one of the rarest. We describe the clinical and laboratory characteristics of a cohort of European anti-PL-7 patients, and compare them with previously reported cases. This multicenter study of patients positive for anti-PL-7, identified between 1984 and 2011, derives from the EUMYONET cohort. Clinical and serologic data were obtained by retrospective laboratory and medical record review, and statistical analyses were performed with chi-squared and Fisher exact tests. Eighteen patients, 15 women, were anti-PL-7 antibody positive. Median follow-up was 5.25 years (interquartile range, 2.8-10.7 yr), and 4 patients died. All patients had myositis (12 polymyositis, 5 dermatomyositis, and 1 amyopathic dermatomyositis), 10 (55.6%) had interstitial lung disease, and 9 (50%) had pericardial effusion. Occupational exposure to organic/inorganic particles was more frequent in patients with interstitial lung disease than in the remaining patients (5 of 10 vs. 1 of 7; p = 0.152), although the difference was not significant. Concurrent autoantibodies against Ro60 and Ro52 were seen in 8 of 14 (57%) patients studied. In the literature review the most common manifestations of anti-PL-7 antisynthetase syndrome were interstitial lung disease (77%), myositis (75%), and arthritis (56%). As in other subsets of the antisynthetase syndrome, myositis and interstitial lung disease are common features of the anti-PL-7 antisynthetase syndrome. In addition, we can add pericarditis as a possible manifestation related to anti-PL-7 antibodies.

KL-6: a serological biomarker for interstitial lung disease in patients with polymyositis and dermatomyositis

OBJECTIVES

To investigate whether Caucasian patients with polymyositis (PM) or dermatomyositis (DM) and interstitial lung disease (ILD) have elevated serum levels of KL-6 compared with patients without ILD and whether KL-6 could be used as a marker for ILD activity and treatment efficacy of ILD in PM/DM.

DESIGN AND METHODS

Thirty patients with PM/DM (seven with ILD) and 17 age- and sex-matched healthy controls were included in a retrospective, cross-sectional analysis. Twelve patients were followed for longitudinal evaluation. ILD was defined as restrictive lung function impairment with radiographic signs of ILD. Serum KL-6 levels were measured using a sandwich enzyme immunoassay kit. Groups were compared by Mann-Whitney U-test.

RESULTS

PM/DM patients with ILD had significantly higher median serum KL-6 levels compared with those without ILD: 995 (range 533-2318) versus 322 (range 132-1225) U mL(-1) (P = 0.0002). Median serum levels of healthy controls were 225 (range 136-519) U mL(-1) . Serum levels of KL-6 were inversely correlated with percentages of forced expiratory volume in 1 s (FEV1), vital capacity (VC), total lung capacity (TLC), forced VC, diffusing capacity of carbon monoxide (DLco), maximal voluntary ventilation at 40 breaths min(-1) and residual volume (RV). Changes in KL-6 levels showed a significant inverse correlation with changes in percentage FEV1, TLC, DLco and RV. At a cut-off level of 549 U mL(-1) (mean ± 2.5 SD for controls), the sensitivity and specificity for diagnosis of ILD were 83% and 100%, respectively.

CONCLUSION

The level of serum KL-6 may serve as measure of ILD in patients with PM/DM and is a promising biomarker for use in clinical practice to assess clinical response to treatment.

Interaction of HLA-DRB1*03 and smoking for the development of anti-Jo-1 antibodies in adult idiopathic inflammatory myopathies: a European-wide case study

Objectives

HLA-DRB1*03 is strongly associated with anti-Jo-1-positive idiopathic inflammatory myopathies (IIM) and there is now increasing evidence that Jo-1 antigen is preferentially expressed in lung tissue. This study examined whether smoking was associated with the development of anti-Jo-1 antibodies in HLA-DRB1*03-positive IIM.

Methods

IIM cases were selected with concurrent information regarding HLA-DRB1 status, smoking history and anti-Jo-1 antibody status. DNA was genotyped at DRB1 using a commercial sequence-specific oligonucleotide kit. Anti-Jo-1 antibody status was established using a line blot assay or immunoprecipitation.

Results

557 Caucasian IIM patients were recruited from Hungary (181), UK (99), Sweden (94) and Czech Republic (183). Smoking frequency was increased in anti-Jo-1-positive IIM cases, and reached statistical significance in Hungarian IIM (45% Jo-1-positive vs 17% Jo-1-negative, OR 3.94, 95% CI 1.53 to 9.89, p<0.0001). A strong association between HLA-DRB1*03 and anti-Jo-1 status was observed across all four cohorts (DRB1*03 frequency: 74% Jo-1-positive vs 35% Jo-1-negative, OR 5.55, 95% CI 3.42 to 9.14, p<0.0001). The frequency of HLA-DRB1*03 was increased in smokers. The frequency of anti-Jo-1 was increased in DRB1*03-positive smokers vs DRB1*03-negative non-smokers (42% vs 8%, OR 7.75, 95% CI 4.21 to 14.28, p<0.0001) and DRB1*03-positive non-smokers (42% vs 31%, p=0.08). In DRB1*03-negative patients, anti-Jo-1 status between smokers and non-smokers was not significantly different. No significant interaction was noted between smoking and DRB1*03 status using anti-Jo-1 as the outcome measure.

Conclusion

Smoking appears to be associated with an increased risk of possession of anti-Jo-1 in HLA-DRB1*03-positive IIM cases. The authors hypothesise that an interaction between HLA-DRB1*03 and smoking may prime the development of anti-Jo-1 antibodies.

Experiencing virtual patients in clinical learning: a phenomenological study

Computerised virtual patients (VPs) are increasingly being used in medical education. With more use of this technology, there is a need to increase the knowledge of students' experiences with VPs. The aim of the study was to elicit the nature of virtual patients in a clinical setting, taking the students' experience as a point of departure. Thirty-one students used VPs as a mandatory part of an early clinical rotation in rheumatology. Using the qualitative approach of phenomenology, we interviewed these students and then analysed data regarding their experiences of VPs as a learning activity. The result shows that students perceived VP activities in relation to actual patients, the clinical context and other learning activities. The VPs represented typical clinical cases which encouraged clinical reasoning and allowed for decision making. The students experienced the activities as integrating biomedical knowledge and clinical experience, providing structure that prepared for the unstructured clinical environment and patient encounters under unstressful conditions. However, the VPs were experienced as lacking the emotional interactivity and complexity of actual patients. Theoretical frameworks of clinical reasoning and experiential learning are suggested as foundations for further educational integration of VPs in the clinical environment. VP activities during clinical rotations provide experiences of clinical reality and allow students to solve problems actively. These features are dependent on VP technology but are also contingent on the surrounding environment.

Polymyositis and dermatomyositis: pathophysiology

Recent advances have increased the understanding of the pathogenesis of polymyositis and dermatomyositis. Clearly, the pathogenesis is complex, and adaptive (eg, autoimmune) and innate and nonimmune pathways play a role in the disease mechanisms, but the relative contribution may vary between patients and in different phases of the disease. Phenotyping patients using autoantibody profiling has resulted in information on molecular pathways that may be relevant in certain subsets of patients with polymyositis or dermatomyositis, but combining the autoantibody profiles with molecular signatures of innate and nonimmune mechanisms would enhance our ability to classify, diagnose, and treat these disorders more effectively.

Expression of APRIL in diffuse large B cell lymphomas from patients with systemic lupus erythematosus and rheumatoid arthritis

OBJECTIVE

Patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) have an increased risk of diffuse large B cell lymphoma (DLBCL). The cytokine A PRoliferating-Inducing Ligand (APRIL) is strongly expressed in DLBCL in the general population and is detected in high concentrations in sera from subgroups of patients with RA and SLE. To investigate a possible association between APRIL and DLBCL in RA and SLE, we examined APRIL expression in lymphoma biopsies from patients with RA and SLE and from DLBCL patients without inflammatory disease.

METHODS

Lymphoma tissue from 95 RA, 12 SLE, and 63 comparator DLBCL cases were stained with anti-APRIL antibodies (Aprily-2). The percentage of positively stained cells of the comparator cases were divided into quartiles (1-4, where 4 = most stained) and compared with the results for the RA and SLE lymphomas. APRIL expression was correlated to clinical variables.

RESULTS

The odds ratio for high expression of APRIL (quartiles 3 and 4) was elevated in the SLE DLBCL (OR 23.6, 95% CI 2.4-231.2), but not in the RA DLBCL (OR 0.8, 95% CI 0.3-2.0). RA patients in quartile 4 had higher cumulated RA disease activity than those in quartile 1 (p = 0.013). Epstein-Barr virus in the lymphoma tissue was associated with high APRIL expression (p = 0.009).

CONCLUSION

The high expression of APRIL in DLBCL in SLE and in an RA subset might indicate an association between APRIL and lymphoma in these subsets of rheumatic diseases, but could also reflect a dysregulation of APRIL per se in these patient groups.