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.

Can muscle regeneration fail in chronic inflammation: a weakness in inflammatory myopathies?

Idiopathic inflammatory myopathies (IIMs), collectively termed myositis, include three major subgroups: polymyositis, dermatomyositis and inclusion body myositis. IIMs are characterized clinically by muscle weakness and reduced muscle endurance preferentially affecting the proximal skeletal muscle. In typical cases, inflammatory cell infiltrates and proinflammatory cytokines, alarmins and eicosanoids are present in muscle tissue. Treatment with glucocorticoids and other immunosuppressants results in improved performance, but complete recovery is rarely seen. The mechanisms that cause muscle weakness and reduced muscle endurance are multi-factorial, and different mechanisms predominate in different phases of disease. It is likely that a combination of immune-mediated and nonimmune-mediated mechanisms contributes to clinical muscle symptoms. Immune-mediated mechanisms include immune cell-mediated muscle fibre necrosis as well as direct effects of various cytokines on muscle fibre contractility. Among the nonimmune-mediated mechanisms, an acquired metabolic myopathy and so-called endoplasmic reticulum stress may be important. There is also a possibility of defective repair mechanisms, with an influence of both disease-related factors and glucocorticoid treatment. Several proinflammatory molecules observed in muscle tissue of myositis patients, including interleukin (IL)-1, IL-15, tumour necrosis factor, high-mobility group box-1 and eicosanoids, have a role in muscle fibre regeneration, and blocking these molecule may impair muscle repair and recovery. The delicate balance between immunosuppressive treatment to downregulate proinflammatory molecules and an inhibitory effect on muscle fibre regeneration needs to be further understood. This would also be relevant for other chronic inflammatory diseases.

Expanded T cell receptor Vβ-restricted T cells from patients with sporadic inclusion body myositis are proinflammatory and cytotoxic CD28null T cells

OBJECTIVE

Sporadic inclusion body myositis (IBM) is characterized by T cell infiltrates in muscle tissue, but their functional role is unclear. Systemic signs of inflammation are lacking, and the absence of beneficial effects following immunosuppression has challenged the notion of a role for the immune system. This study was undertaken to investigate the phenotype and functionality of T cells, specifically a subset of proinflammatory, cytotoxic, and apoptosis-resistant T cells defined as CD28(null) T cells, in the pathogenesis of sporadic IBM.

METHODS

A cohort of 27 patients with sporadic IBM was analyzed for the frequency of circulating and muscle-infiltrating CD28(null) T cells. The T cell receptor (TCR) V(β) usage was determined using flow cytometry and immunohistochemistry. Anti-CD3-stimulated peripheral blood mononuclear cells were analyzed for intracellular interferon-γ and cytotoxic potential by flow cytometry.

RESULTS

We found striking accumulations of both CD8+CD28(null) and CD4+CD28(null) T cells, which represented the TCR V(β) -expanded T cells in sporadic IBM. Such CD28(null) T cells were abundant both in the inflamed muscle tissue and in the circulation. Although the specific TCR V(β) expansions varied between patients, both CD8+CD28(null) and CD4+CD28(null) T cells consistently displayed a highly proinflammatory and cytotoxic potential.

CONCLUSION

Our results suggest that CD28null T cell expansions represent the previously described expanded T cell subsets in sporadic IBM, and their proinflammatory capacity and presence in both muscle tissue and the circulation may imply a role of immune activation in sporadic IBM. In addition, CD4+CD28(null) T cells may exert cytotoxic effects directly on muscle fibers due to a cytotoxic potential similar to that in CD8+ T cells.

Patients with polymyositis or dermatomyositis have reduced grip force and health-related quality of life in comparison with reference values: an observational study

OBJECTIVES

The aims of this study were to investigate hand function in PM and DM patients and compare this with reference values in healthy individuals and also to investigate if hand function correlated with activity performance and health-related quality of life.

METHODS

An observational cross-sectional study was performed in 18 women and 13 men with PM or DM with established disease. Grip force and hand mobility were assessed by Grippit and Escola Paulista de Medicina-Range of Motion scale. Activity performance was measured with myositis activities profile and health-related quality of life by short form-36 (SF-36).

RESULTS

Women and men with PM and DM with mean disease duration of 6.8 (5.5) years had a significantly lower grip force than gender- and age-matched healthy individuals (women 71% and men 60%). They also had significantly lower mean values in all dimensions of the health-related quality of life instrument SF-36 compared with the Swedish population. In patients with PM and DM, the grip force correlated significantly with the ability to perform domestic activities. In women with PM and DM, the grip force correlated significantly with the health-related quality of life dimensions vitality and mental health. There were no significant differences between patients with PM and DM regarding grip force, hand mobility, activity performance or health-related quality of life.

CONCLUSIONS

Patients with PM or DM have reduced grip force that could influence activity performance and health-related quality of life.

Higher proportion of fast-twitch (type II) muscle fibres in idiopathic inflammatory myopathies - evident in chronic but not in untreated newly diagnosed patients

OBJECTIVE

Polymyositis and dermatomyositis are idiopathic, inflammatory myopathies characterized by proximal muscle fatigue. Conventional immunosuppressive treatment gives a variable response. Biopsies from chronic patients display a low proportion type I and a high proportion of type II muscle fibres. This raised a suspicion that the low proportion of type I fibres might play a role in the muscle fatigue.

AIM

To investigate whether the muscle fibre attributes evident in chronic myositis are characteristic for the polymyositis and dermatomyosistis diseases themselves.

METHODS

Muscle biopsies were obtained from thigh muscle from untreated patients (n = 18), treated responders (n = 14) and non-responders (n = 6) and from healthy controls (n = 11), respectively. For clinical evaluations, creatine kinase, functional index of myositis and cumulative dose of cortisone were established.

RESULTS

  Chronic patients had a lower proportion of type I fibres and a higher proportion of type II fibres compared to untreated myositis patients and healthy controls. Fibre cross-sectional area (CSA) did not differ between patients and healthy individuals but all women had a 20% smaller type II fibre CSA compared to men.

CONCLUSIONS

Untreated polymyositis and dermatomyositis patients and healthy controls have a different fibre type composition than chronic polymyositis and dermatomyositis patients. Fibre CSA did not differ between healthy controls or any of the patient groups. A low proportion of oxidative muscle fibres can therefore be excluded as a contributing factor causing muscle fatigue at disease onset and the gender difference should be taken into consideration when evaluating fibre CSA in myositis.

Diagnostic performance and validation of autoantibody testing in myositis by a commercial line blot assay

OBJECTIVE

Serological testing for myositis-specific or associated autoantibodies [myositis-specific antibody (MSA) and myositis-associated antibody (MAA)] is useful for the diagnosis of idiopathic inflammatory myopathies (IIMs). However, available assays are neither standardized nor validated. The objective is to evaluate the accuracy of a commercial line blot assay for myositis diagnosis.

METHODS

IgG antibodies against Jo-1, PL-7, PL-12, PM/Scl, Ku, Mi-2 and Ro52 antigens were detected by a line blot and in-house RNA immunoprecipitation or immunoblot. We tested sera from 208 IIM patients, 50 healthy subjects and 180 control patients (11 non-autoimmune myopathy, 23 muscular dystrophy, 11 UCTD, 68 SLE, 36 SSc, 22 SS and 9 arthropathy).

RESULTS

MSAs or MAAs were detected in 98 (47%) out of the 208 IIM patients by line blot: anti-Jo-1 in 43 (21%), anti-PL-7 or anti-PL-12 in 8 (4%), anti-Mi-2 in 9 (4%), anti-PM/Scl in 9 (4%), anti-Ku in 10 (5%) and anti-Ro52 in 49 (24%). Overall specificity was: 100% for anti-Jo-1, anti-PL-7 or PL-12 and anti-PM/Scl; 96% for anti-Ku; 98% for anti-Mi-2; and 76% for anti-Ro52. In-house testing confirmed line blot results regarding anti-Jo-1, anti-PM/Scl and anti-Ku, while it was more accurate than line blot in detecting anti-Mi-2 (7 vs 4% sensitivity, 100 vs 98% specificity), and anti-aminoacyl-tRNA synthetase (anti-ARS) non-Jo-1 antibodies (11 vs 4% sensitivity, 97 vs 99% specificity).

CONCLUSIONS

Line blot could be a suitable serological test in the diagnostic workup for myositis, and it represents a reliable alternative to more time-consuming procedures. Continuous effort is recommended in order to improve its accuracy.

A longitudinal, integrated, clinical, histological and mRNA profiling study of resistance exercise in myositis

Polymyositis and dermatomyositis are orphan, chronic skeletal muscle disorders characterized by weakness, infiltrations by mononuclear inflammatory cells, and fibrosis. Until recently, patients were advised to refrain from physical activity because of fears of exacerbation of muscle inflammation. However, recent studies have shown that moderate exercise training in combination with immunosuppressive drugs can improve muscle performance. Despite the positive effects of exercise training, the molecular mechanisms underlying the exercise-associated clinical improvements remain poorly understood. The present study was designed to define, at the molecular level, the effects of resistance exercise training on muscle performance and disease progression in myositis patients. We evaluated changes in muscle strength, histology and genome-wide mRNA profiles to determine the beneficial effects of exercise and determine the possible molecular changes associated with improved muscle performance. A total of 8 myositis patients underwent a 7-wk resistance exercise training program that resulted in improved muscle strength and increased maximal oxygen uptake (VO(2max)). Training also resulted in marked reductions in gene expression, reflecting reductions in proinflammatory and profibrotic gene networks, changes that were also accompanied by a reduction in tissue fibrosis. Consistent with the exercise-associated increase in VO(2max), a subset of transcripts was associated with a shift toward oxidative metabolism. The changes in gene expression reported in the present study are in agreement with the performance improvements induced by exercise and suggest that resistance exercise training can induce a reduction in inflammation and fibrosis in skeletal muscle.

The type I interferon system in idiopathic inflammatory myopathies

Polymyositis (PM), dermatomyositis (DM) and inclusion body myositis (IBM) are chronic inflammatory diseases that are characterized by muscle weakness and inflammatory cells in muscle tissue. Autoantibodies are common, some of them are specific for myositis, the most frequent being the anti-Jo-1 antibody which is associated not only with myositis but also with interstitial lung disease and arthritis. A role of type I interferons in disease mechanisms of myositis was first supported by the reported onset of PM and DM during treatment with type I interferon. More recently an interferon signature has been reported in muscle tissue of DM and PM patients both as gene and protein expression, and type I IFN expression in peripheral blood cells seems to correlate with disease activity. Different mechanisms could induce type I interferon in PM and DM like viral infections or endogenous factors as suggested by the observation that sera from myositis patients with anti-Jo-1 antibodies as well as anti-SSA and anti-SSB antibodies have an interferon inducible capacity. Accumulating data indicate a role of the type I interferon in myositis, particularly in juvenile and adult DM and in anti-Jo-1 or anti-SSA positive PM.

Impaired myofibrillar function in the soleus muscle of mice with collagen-induced arthritis

OBJECTIVE

Progressive muscle weakness is a common feature in patients with rheumatoid arthritis (RA). However, little is known about whether the intrinsic contractile properties of muscle fibers are affected in RA. This study was undertaken to investigate muscle contractility and the myoplasmic free Ca2+ concentration ([Ca2+](i)) in the soleus, a major postural muscle, in mice with collagen-induced arthritis (CIA).

METHODS

Muscle contractility and [Ca2+](i) were assessed in whole muscle and intact single-fiber preparations, respectively. The underlying mechanisms of contractile dysfunction were assessed by investigating redox modifications using Western blotting and antibodies against nitric oxide synthase (NOS), superoxide dismutase (SOD), 3-nitrotyrosine (3-NT), carbonyl, malondialdehyde (MDA), and S-nitrosocysteine (SNO-Cys).

RESULTS

The tetanic force per cross-sectional area was markedly decreased in the soleus muscle of mice with CIA, and the change was not due to a decrease in the amplitude of [Ca2+](i) transients. The reduction in force production was accompanied by slowing of the twitch contraction and relaxation and a decrease in the maximum shortening velocity. Immunoblot analyses showed a marked increase in neuronal NOS expression but not in inducible or endothelial NOS expression, which, together with the observed decrease in SOD2 expression, favors peroxynitrite formation. These changes were accompanied by increased 3-NT, carbonyl, and MDA adducts content in myofibrillar proteins from the muscles of mice with CIA. Moreover, there was a significant increase in SNO-Cys content in myosin heavy-chain and troponin I myofibrillar proteins from the soleus muscle of mice with CIA.

CONCLUSION

These findings show impaired contractile function in the soleus muscle of mice with CIA and suggest that this abnormality is due to peroxynitrite-induced modifications in myofibrillar proteins.

Predictors of the first cardiovascular event in patients with systemic lupus erythematosus - a prospective cohort study

Introduction

Cardiovascular disease (CVD) is a major cause of premature mortality among Systemic lupus erythematosus (SLE) patients. Many studies have measured and evaluated risk factors for premature subclinical atherosclerosis, but few studies are prospective and few have evaluated risk factors for hard endpoints, i.e. clinically important cardiovascular events (CVE). We investigated the impact of traditional and lupus associated risk factors for the first ever CVE in a longitudinal cohort of SLE patients.

Methods

A total of 182 SLE patients (mean age 43.9 years) selected to be free of CVE were included. Cardiovascular and autoimmune biomarkers were measured on samples collected after overnight fasting at baseline. Clinical information was collected at baseline and at follow up. End point was the first ever CVE (ischemic heart, cerebrovascular or peripheral vascular disease or death due to CVD). Impact of baseline characteristics/biomarkers on the risk of having a first CVE was evaluated with Cox regression.

Results

Follow up was 99.5% after a mean time of 8.3 years. Twenty-four patients (13%) had a first CVE. In age-adjusted Cox regression, any positive antiphospholipid antibody (aPL), elevated markers of endothelial activation (von Willebrand factor (vWf), soluble vascular cellular adhesion molecule-1 (sVCAM-1)) and fibrinogen predicted CVEs. Of SLE manifestations, arthritis, pleuritis and previous venous occlusion were positively associated with future CVEs while thrombocytopenia was negatively associated. Among traditional risk factors only age and smoking were significant predictors. In a multivariable Cox regression model age, any positive aPL, vWf and absence of thrombocytopenia were all predictors of the first CVE.

Conclusions

In addition to age, positive aPL, biomarkers indicating increased endothelial cell activity/damage, and absence of thrombocytopenia were independent predictors of CVEs in this prospective study. Our results indicate that activation of the endothelium and the coagulation system are important features in SLE related CVD. Furthermore, we observed that the risk of CVEs seems to differ between subgroups of SLE patients.

Effects of HMGB1 on in vitro responses of isolated muscle fibers and functional aspects in skeletal muscles of idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIMs) are heterogeneous rheumatic disorders of unknown cause characterized by muscle weakness, inflammatory cell infiltrates, and major histocompatibility complex (MHC) class I expression on muscle fibers. The nonhistone nuclear protein alarmin high-mobility group box 1 protein (HMGB1) has been detected extranuclearly in muscle biopsies from patients with IIMs. We hypothesize that HMGB1 has a central role in the cause of muscle weakness, particularly in the early phases of IIMs. Experiments were performed on skeletal muscle fibers isolated from adult mice, which were exposed to recombinant interferon (IFN)-gamma or HMGB1. The myoplasmic free [Ca(2+)] was measured. Stimulation with IFN-gamma resulted in increased HMGB1 expression in muscle nuclei and the myoplasm. Exposure to HMGB1 induced a reversible up-regulation of MHC class I in the muscle fibers. However, HMGB1 exposure caused an irreversible decrease in Ca(2+) release from the sarcoplasmic reticulum during fatigue, induced by repeated tetanic contractions. HMGB1 and MHC class I were frequently colocalized in the myoplasm of muscle fibers in muscle biopsies from patients with early IIMs. However, HMGB1-expressing fibers outnumbered fibers expressing MHC class I. Our data indicate that HMGB1 could be an early inducer of skeletal muscle dysfunction in IIMs.

Sera from anti-Jo-1-positive patients with polymyositis and interstitial lung disease induce expression of intercellular adhesion molecule 1 in human lung endothelial cells

OBJECTIVE

To investigate whether sera or purified IgG from patients with polymyositis (PM) and patients with dermatomyositis (DM), with or without interstitial lung disease (ILD), can activate endothelial cells (ECs).

METHODS

Patients' sera were selected based on the presence or absence of anti-Jo-1, anti-SSA, or anti-U1 small nuclear RNP autoantibodies. The presence of autoantibodies was determined by line blot assays. Cultured human microvascular ECs derived from lung tissue (HMVEC-L) were incubated with sera or purified IgG from 22 patients with PM, 7 patients with DM, and 10 healthy individuals as controls. Assessment of intercellular adhesion molecule 1 (ICAM-1) expression was conducted by immunofluorescence (n=22) and by cell-based enzyme-linked immunosorbent assay (ELISA) (n=20). Serum levels of soluble ICAM-1 (sICAM-1) were determined by ELISA.

RESULTS

Sera from PM patients with ILD who were positive for anti-Jo-1 autoantibodies had a significantly stronger effect on the expression of ICAM-1 by HMVEC-L in comparison with sera from healthy controls and patients with other autoantibodies. Purified IgG did not induce ICAM-1 expression. Higher serum levels of sICAM-1 were found in patients with myositis compared with healthy controls.

CONCLUSION

EC activation with ICAM-1 expression could contribute to the multiorgan involvement, including the development of myositis and ILD, in patients carrying anti-Jo-1 autoantibodies. The EC-activating factors are not the autoantibodies themselves, but might be systemic factors associated with these autoantibodies.

T cell infiltrates in the muscles of patients with dermatomyositis and polymyositis are dominated by CD28null T cells

Dermatomyositis and polymyositis are disabling rheumatic diseases characterized by an appreciable number of T cells infiltrating muscle tissue. The precise phenotype, function and specificity of these cells remain elusive. In this study, we aimed to characterize T cells in muscle tissue and circulation and to investigate their association to clinical phenotype. Twenty-four patients with dermatomyositis and 42 with polymyositis were screened for frequency of CD4+CD28(null) and CD8+CD28(null) T cells in peripheral blood by flow cytometry. Presence of these cells in inflamed muscle tissue from 13 of these patients was analyzed by three-color immunofluorescence microscopy. Effector functions, proliferation and Ag specificity were analyzed by flow cytometry after in vitro stimulation. The clinical relevance of CD28(null) T cells was analyzed by multiple regression analyses including six separate and combined disease variables. We demonstrate that muscle-infiltrating T cells are predominantly CD4+CD28(null) and CD8+CD28(null) T cells in patients with dermatomyositis and polymyositis. Muscle-infiltrating CD28(null) T cells were found already at time of diagnosis. Disease activity correlated with the frequency of CD8+ T cells in the inflamed muscles of polymyositis patients. Circulating CD4+CD28(null) and CD8+CD28(null) T cells were significantly more frequent in human CMV (HCMV) seropositive individuals, responded to HCMV Ag stimulation, and correlated with disease duration. These cells also display a proinflammatory cytokine profile, contain perforin and lack the costimulatory molecule CD28. Our observations imply that CD28(null) T cells represent clinically important effector cells in dermatomyositis and polymyositis, and that HCMV might play a role in propagating disease in a subset of patients.

Myeloid leukaemia in systemic lupus erythematosus--a nested case-control study based on Swedish registers

OBJECTIVE

To assess the risk factors for leukaemic transformation and myeloid leukaemia in patients with SLE.

METHODS

A national SLE cohort identified through SLE discharge diagnoses in the Swedish hospital discharge register during 1964 to 1995 (n = 6438) was linked to the national cancer register. A nested case-control study in SLE patients who developed acute or chronic myeloid leukaemia was performed with SLE patients without malignancy as controls. Medical records from cases and controls were reviewed and bone marrow specimens were re-evaluated. A Medline search of previously published cases of SLE and myeloid leukaemia was performed.

RESULTS

After confirmation of SLE diagnosis according to the ACR criteria, eight patients with SLE and myeloid leukaemia and 18 SLE controls were included in the study. Preceding leucopenia was significantly associated with leukaemia development, whereas other SLE manifestations were not. Two cases had a preceding bone marrow confirming myelodysplastic syndrome (MDS). Only two cases were significantly treated with cyclophosphamide or AZA. A Medline search resulted in only 15 previously published cases of coincident SLE and myeloid leukaemia. Preceding MDS was reported in five of these, whereas only eight had been treated with cytotoxic drugs.

CONCLUSION

Low-dose chemotherapy was not a major cause of myeloid malignancy in our population-based cohort of SLE patients nor in the reported cases from literature. Leucopenia was a risk factor for myeloid leukaemia development and an MDS was frequently seen. Therefore bone marrow investigation should be considered in SLE patients with long-standing leucopenia and anaemia.

Cytokines in idiopathic inflammatory myopathies

Recent findings suggest cytokines as important key molecules in the pathogenic mechanisms of idiopathic inflammatory myopathies, myositis. In this review, we focus on cytokines with a potential role in disease mechanisms in myositis and present some general information on individual cytokines and an updated summary from the literature concerning cytokines in these disorders. The idiopathic inflammatory myopathies is a heterogeneous group of disorders clinically characterized by symmetric proximal muscle weakness and by certain defined histolopathological findings, including inflammatory infiltrates in muscle tissue. Other prominent findings in the target tissue of these patients are defined molecular changes of blood vessels and muscle fibers, including reformation to high endothelial venule (HEV)-like blood vessels and intensive MHC class I expression in muscle fibers. The predominant clinical symptoms of muscle weakness and decreased muscle endurance are shared by all subsets of inflammatory myopathies and indicate that some pathogenic mechanisms related to muscle function may be shared by the different disease groups. Studies on cytokine gene, RNA and protein expression in muscle tissue from patients with various forms of the disease also indicate similar profiles, despite different phenotypes of the inflammatory cells present in muscle tissue from the different subsets of myositis. There is a pronounced expression of various cytokines in muscle tissue, among which the proinflammatory cytokines TNF-alpha and IL-1 are most widely explored in the inflammatory myopathies, which has made them into potential therapeutic targets. The use of targeted cytokine therapy has been successful in several other chronic inflammatory diseases and although the exact role of cytokines in chronic idiopathic inflammatory myopathies remains to be delineated their potential role as targets for new therapies in this disorder will be discussed in this review.

Upregulation of MHC class I in transgenic mice results in reduced force-generating capacity in slow-twitch muscle

Expression of major histocompatibility complex (MHC) class I in skeletal muscle fibers is an early and consistent finding in inflammatory myopathies. To test if MHC class I has a primary role in muscle impairment, we used transgenic mice with inducible overexpression of MHC class I in their skeletal muscle cells. Contractile function was studied in isolated extensor digitorum longus (EDL, fast-twitch) and soleus (slow-twitch) muscles. We found that EDL was smaller, whereas soleus muscle was slightly larger. Both muscles generated less absolute force in myopathic compared with control mice; however, when force was expressed per cross-sectional area, only soleus muscle generated less force. Inflammation was markedly increased, but no changes were found in the activities of key mitochondrial and glycogenolytic enzymes in myopathic mice. The induction of MHC class I results in muscle atrophy and an intrinsic decrease in force-generation capacity. These observations may have important implications for our understanding of the pathophysiological processes of muscle weakness seen in inflammatory myopathies. Muscle Nerve, 2008.

Reliability and validity of the myositis disease activity assessment tool

OBJECTIVE

To test the interrater reliability and validity of the Myositis Disease Activity Assessment Tool, which consists of the Myositis Intention-to-Treat Activity Index and the Myositis Disease Activity Assessment Visual Analog Scales.

METHODS

Two phases of the study were conducted to assess the reliability and validity of the tool, which was modified following the first phase. In the first phase of the reliability study, 123 adult myositis patients were evaluated in 7 centers, and in the second phase 40 patients were evaluated in 2 centers. The validity study included 294 patients in 5 centers in the first phase and 65 patients in 3 centers in the second phase. The interrater reliability was assessed using intraclass correlation coefficients. The criterion validity was calculated using sensitivity, specificity, and positive predictive value (PPV) of a grade of A in any system. Spearman's rank correlation coefficient was used to measure the convergent validity of cross-sectional scores between the 2 instruments.

RESULTS

There was a 2:1 ratio of female to male patients. There was no significant difference in mean age at diagnosis (46.3 versus 46.8 years) and mean disease duration (7.7 versus 10 years) between the 2 groups recruited for the different phases of the study. There was an improvement in interrater reliability in the second phase of the study. There was a significant improvement in the validity of the assessment tool following modification of the tool. The sensitivity, specificity, and PPV of a grade of A in any system improved from 86%, 92%, and 67% in the first phase to 96%, 94%, and 83%, respectively, in the second phase. Convergent validity between the 2 activity tools showed good correlation, ranging from 0.8 to 0.94, for the individual organ systems.

CONCLUSION

This is the first major attempt to assess the reliability and validity of a disease activity index in myositis. Our findings indicate that, following within-study modification, the tool appears to be a reliable and valid instrument to assess myositis disease activity.

Developments in the scientific and clinical understanding of inflammatory myopathies

The idiopathic inflammatory myopathies are chronic autoimmune disorders sharing the clinical symptom of muscle weakness and, in typical cases, inflammatory cell infiltrates in muscle tissue. During the last decade, novel information has accumulated supporting a role of both the innate and adaptive immune systems in myositis and suggesting that different molecular pathways predominate in different subsets of myositis. The type I interferon activity is one such novel pathway identified in some subsets of myositis. Furthermore, nonimmunological pathways have been identified, suggesting that factors other than direct T cell-mediated muscle fibre necrosis could have a role in the development of muscle weakness.

Increased serum levels of B cell activating factor (BAFF) in subsets of patients with idiopathic inflammatory myopathies

OBJECTIVE

To investigate serum levels of B cell activating factor (BAFF) in patients with myositis and correlate these to autoantibody profile, clinical phenotype and treatment.

METHODS

BAFF levels in sera from 49 patients with dermatomyositis, 44 with polymyositis, 6 with inclusion body myositis and 30 matched controls were measured by ELISA. Specific autoantibodies were detected by line blot and western blot assays.

RESULTS

Serum levels of BAFF were significantly higher in patients compared to healthy controls (p = 0.003). Patients with anti-Jo-1 autoantibodies had higher BAFF levels than control individuals (p<0.003) or patients without any specific autoantibodies (p<0.05). Patients with dermatomyositis had higher BAFF levels compared to polymyositis (p<0.05). Patients with interstitial lung disease (ILD) had higher BAFF levels than patients without ILD (p<0.05) or controls (p<0.01) but this could be explained by presence of anti-Jo-1 autoantibodies. BAFF levels correlated with serum creatine kinase (CK) (rs = 0.365, p = 0.0005) but not with C-reactive protein (CRP) levels. A negative correlation of BAFF levels with glucocorticoid daily dose for all patients (rs = -0.292, p = 0.003) and with cumulative glucocorticoid doses in early myositis cases (rs = -0.659, p<0.001) was recorded.

CONCLUSION

Our finding of elevated serum levels of BAFF in patients with myositis with described phenotypes together with the correlations between levels of BAFF and CK and a negative correlation with dose of glucocorticoids, indicate that BAFF could be a potential therapeutic target in such cases.

Aerobic capacity correlates to self-assessed physical function but not to overall disease activity or organ damage in women with systemic lupus erythematosus with low-to-moderate disease activity and organ damage

The present aim is to investigate the relationships between aerobic capacity and disease activity, organ damage, health-related quality of life (HRQL) and physical activity in 34 women with systemic lupus erythematosus (SLE) with low-to-moderate disease activity and organ damage. Mean age was 51 (SD 10) years, disease duration 17 (SD 11) years. Aerobic capacity (maximal oxygen uptake/VO2 max) was measured with a bicycle ergometer exercise test. Overall disease activity was assessed with Systemic Lupus Activity Measure (SLAM) and the modified Systemic Lupus Erythematosus-Disease Activity Index (modified SLE-DAI), overall organ damage with the Systemic Lupus International Collaboration Clinics/American College of Rheumatology-Damage Index, [SLICC/(ACR)-DI], HRQL with the 36-item Short-form health-survey (SF-36) and physical activity with a self-assessed question. The women who were low-to-moderately physically active had 89-92% (P < or = 0.001) of VO2 max predicted for sedentary women. Maximal oxygen uptake (L/min, mL/min/kg) correlated to SF-36 physical function (rs = 0.49, rs = 0.72) (P < or = 0.01), but not (rs < or = 0.25) to other HRQL scales, overall disease activity or organ damage or physical activity. The correlation between aerobic capacity and physical function and the absence of correlation between aerobic capacity and physical activity, suggest a possible disease-related factor behind the low aerobic capacity. However, with no correlation between aerobic capacity and overall disease activity and organ damage, low physical activity may contribute to the low aerobic capacity in our sample.

A high incidence of disease flares in an open pilot study of infliximab in patients with refractory inflammatory myopathies

OBJECTIVE

To investigate the effect of the tumour necrosis factor (TNF) blocking agent infliximab in patients with treatment-resistant inflammatory myopathies.

METHODS

A total of 13 patients with refractory polymyositis (PM), dermatomyositis (DM), or inclusion body myositis (IBM) were treated with 4 infliximab infusions (5 mg/kg body weight) over 14 weeks. Outcome measures included myositis disease activity score with improvement defined according to The International Myositis Assessment and Clinical Studies Group (IMACS), and MRI. Repeated muscles biopsies were investigated for cellular infiltrates, major histocompatibility complex (MHC) class I and II, TNF, interleukin (IL)1alpha, IL6, high mobility group box chromosomal protein 1 (HMGB-1), interferon gamma (IFNgamma), myxovirus resistance protein A (MxA) and membrane attack complex (MAC) expression. Type I IFN activity was analysed in sera.

RESULTS

Nine patients completed the study. Three patients discontinued due to adverse events and one due to a discovered malignancy. Three of the completers improved by >or=20% in three or more variables of the disease activity core set, four were unchanged and two worsened >or=30%. No patient improved in muscle strength by manual muscle test. At baseline, two completers had signs of muscle inflammation by MRI, and five at follow-up. T lymphocytes, macrophages, cytokine expression and MAC deposition in muscle biopsies were still evident after treatment. Type I IFN activity was increased after treatment.

CONCLUSIONS

Infliximab treatment was not effective in refractory inflammatory myopathies. In view of radiological and clinical worsening, and activation of the type I IFN system in several cases, infliximab is not an alternative treatment in patients with treatment-resistant myositis.

Effects of immunosuppressive treatment on microsomal prostaglandin E synthase 1 and cyclooxygenases expression in muscle tissue of patients with polymyositis or dermatomyositis

OBJECTIVES

To investigate the expression of microsomal prostaglandin E (PGE) synthase 1 (mPGES-1) and cyclooxygenase (COX) in muscle biopsies from patients with polymyositis or dermatomyositis before and after conventional immunosuppressive treatment.

METHODS

mPGES-1 and COX expression was evaluated by immunohistochemistry in muscle tissue from healthy individuals and from patients with polymyositis or dermatomyositis before and after conventional immunosuppressive treatment. The number of inflammatory cell infiltrates, T lymphocytes and macrophages was estimated before and after treatment. To localise the mPGES-1 expression double immunofluorescence was performed with antibodies against mPGES-1, CD3, CD68, CD163 and a fibroblast marker. A functional index was used to assess muscle function.

RESULTS

In patients with myositis, mPGES-1, COX-2 and COX-1 expression was significantly higher compared to healthy individuals and associated with inflammatory cells. Double immunofluorescence demonstrated a predominant expression of mPGES-1 in macrophages. Conventional immunosuppressive treatment resulted in improved but still lower muscle function than normal. A decreased number of CD68-positive macrophages and reduced COX-2 expression in muscle tissue was also seen. By contrast, following the same treatment no significant changes were observed in muscle tissue regarding number of infiltrates, T lymphocytes, CD163-positive macrophages or mPGES-1 protein levels.

CONCLUSIONS

Increased expression of mPGES-1, COX-1 and COX-2 at protein level was observed in muscle tissue from patients with myositis compared to healthy individuals. Conventional immunosuppressive treatment led to a significant downregulation of COX-2 in myositis muscle tissue. However, the expression of mPGES-1 and COX-1 remained unchanged indicating a role of these enzymes in the chronicity of these diseases.

Effect of physical training on the proportion of slow-twitch type I muscle fibers, a novel nonimmune-mediated mechanism for muscle impairment in polymyositis or dermatomyositis

OBJECTIVE

To compare muscle fiber type composition and muscle fiber area in patients with chronic polymyositis or dermatomyositis and healthy controls, and to determine whether physical training for 12 weeks could alter these muscle characteristics.

METHODS

Muscle fiber type composition and muscle fiber area were investigated by biochemical and immunohistochemistry techniques in repeated muscle biopsy samples obtained from 9 patients with chronic myositis before and after a 12-week exercise program and in healthy controls. Muscle performance was evaluated by the Functional Index (FI) in myositis and by the Short Form 36 (SF-36) quality of life instrument.

RESULTS

Before exercise, the proportion of type I fibers was lower (mean +/- SD 32% +/- 10%) and the proportion of type IIC fibers was higher (3% +/- 3%) in patients compared with healthy controls. After exercise, percentage of type I fiber increased to 42% +/- 13% (P < 0.05), and type IIC decreased to 1% +/- 1%. An exercise-induced 20% increase of the mean fiber area was also observed. The functional capacity measured by the FI in myositis and the physical functioning subscale of the SF-36 increased significantly. Improved physical functioning was positively correlated with the proportion of type I fibers (r = 0.88, P < 0.01) and type II muscle fiber area (r = 0.70, P < 0.05).

CONCLUSION

Low muscle endurance in chronic polymyositis or dermatomyositis may be related to a low proportion of oxidative, slow-twitch type I fibers. Change in fiber type composition and increased muscle fiber area may contribute to improved muscle endurance and decreased muscle fatigue after a moderate physical training program.

A possible mechanism for endogenous activation of the type I interferon system in myositis patients with anti-Jo-1 or anti-Ro 52/anti-Ro 60 autoantibodies

OBJECTIVE

To investigate type I interferon (IFN) system activation and its correlation with autoantibodies and organ manifestations in polymyositis (PM), dermatomyositis (DM), and inclusion body myositis.

METHODS

Sera from 30 patients and 16 healthy controls, or purified IgG, were combined with material released from necrotized cells to stimulate IFNalpha production by peripheral blood mononuclear cells (PBMCs) from healthy blood donors. Muscle biopsy specimens from 25 patients and 7 healthy controls were investigated for blood dendritic cell antigen 2 (BDCA-2)-positive plasmacytoid dendritic cells (PDCs) and IFNalpha/beta-inducible myxovirus resistance 1 (MX-1) protein.

RESULTS

Sera from 13 patients who were positive for anti-Jo-1 or anti-Ro 52/anti-Ro 60 autoantibodies induced IFNalpha production in PBMCs when combined with necrotic cell material. In addition, IgG prepared from anti-Jo-1-positive PM sera induced IFNalpha with necrotic material, but not when the latter was treated with RNase. BDCA-2 expression in PDCs in muscle tissue was increased in PM patients with anti-Jo-1 autoantibodies, while MX-1 staining in capillaries was increased in DM patients, compared with healthy individuals. IFNalpha-inducing capacity correlated with interstitial lung disease, while MX-1 expression in the capillaries correlated with DM.

CONCLUSION

Immune complexes containing anti-Jo-1 or anti-Ro 52/anti-Ro 60 autoantibodies and RNA may act as endogenous IFNalpha inducers that activate IFNalpha production in PDCs. These PDCs could be of importance for inducing myositis, whereas in DM patients without autoantibodies the presence of MX-1 protein in capillaries suggests another cellular IFNalpha source and induction mechanism. Consequently, the type I IFN system may be of importance in both PM and DM, but via different pathways.

Immune mechanisms in the pathogenesis of idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIMs), comprising polymyositis, dermatomyositis, and inclusion-body myositis, are characterized by inflammatory cell infiltrates in skeletal muscle tissue, muscle weakness, and muscle fatigue. The cellular infiltrates often consist of T lymphocytes and macrophages but also, in some cases, B lymphocytes. Emerging data have led to improved phenotypic characterization of the inflammatory cells, including their effector molecules, in skeletal muscle, peripheral blood, and other organs that are frequently involved, such as skin and lungs. In this review we summarize the latest findings concerning the role of T lymphocytes, B lymphocytes, dendritic cells, and other antigen-presenting cells in the pathophysiology of IIMs.

Disease-specific quality indicators, outcome measures and guidelines in polymyositis and dermatomyositis

Polymyositis and dermatomyositis are chronic inflammatory muscle disorders with frequent involvement of other organs hence outcome measures should include these different aspects of disease. Muscle strength and muscle endurance are the most specific clinical features that should be assessed during treatment and longitudinal follow-up. Extramuscular involvement should also be assessed. An international, interdisciplinary network, the International Myositis Assessment Clinical Study Group (IMACS) has proposed a core set of outcome measures to assess three dimensions of myositis disease; disease activity (MYOACT), disease damage (MYODAM) and health related quality of life (SF-36) to be used in clinical trials. These include scoring of extramuscular involvement (skin, lungs, articular, cardiac, gastro-intestinal tract) in both the disease activity and damage scores. In the disease activity score, muscle strength is measured by the manual muscle test (MMT)- 8, this could easily be used in clinical practice. Other myositis specific outcome measures are the Functional Index of myositis (FI) -- 2 to measure muscle endurance and a questionnaire, the Myo-sitis Activities Profile (MAP) to measure patient perspective. A close collaboration between physicians, physical and occupational therapists and specialized nurses is of great value in care and disease assessment of patients with polymyositis and dermatomyositis.

International consensus on a proposed score system for muscle biopsy evaluation in patients with juvenile dermatomyositis: A tool for potential use in clinical trials

OBJECTIVE

To devise and test a system with which to evaluate abnormalities on muscle biopsy samples obtained from children diagnosed with juvenile dermatomyositis (DM).

METHODS

We established an International Consensus Group on Juvenile DM Biopsy and carried out 2 phases of consensus process and scoring workshops. Biopsy sections (n = 33) were stained by standard methods. The scoring tool was based on 4 domains of change: inflammatory, vascular, muscle fiber, and connective tissue. Using a Latin square design, biopsy samples were scored by 11 experts for items in each domain, and for a global abnormality measure using a 10-cm visual analog score (VAS 0-10). The tool's reliability was assessed using an intraclass correlation coefficient (ICC) and scorer agreement (alpha) by determining variation in scorers' ratings.

RESULTS

There was good agreement in many items of the tool, and several items refined between the meetings improved in reliability and/or agreement. The inflammatory and muscle fiber domains had the highest reliability and agreement. The overall VAS score for abnormality had high agreement and reliability, reaching an ICC of 0.863 at the second consensus meeting.

CONCLUSION

We propose a provisional scoring system to measure abnormalities on muscle biopsy samples obtained from children with juvenile DM. This system needs to be validated, and then could be used in prospective studies to test which features of muscle pathology are prognostic of disease course or outcome. We suggest that the process we used could be a template for developing similar systems in other forms of myositis.

Inflammatory muscle disease: clinical presentation and assessment of patients

Muscle weakness and muscle fatigue are the most common manifestations in patients with idiopathic inflammatory myopathies (ie, myositis), but other organs are frequently involved such as skin, lungs, joints, and the heart. These could occur before, simultaneously with, or after the onset of muscle symptoms. One tool to structure outcome measure is the International Classification of Functioning, Disability, and Health. Measures of "disability" can be divided into impairment and activity limitation/participation restriction. Most of the available outcome measures for myositis could be classified as measures of impairment, such as muscle strength, serum levels of muscle enzymes, and pulmonary function tests. Measures of activity limitation/participation restriction are also important, such as the myositis activities profile, the visual analog scale to assess impact on general well-being, and the generic short form-36 to capture impact on health-related quality of life.

Pulmonary Complications of Polymyositis and Dermatomyositis

Polymyositis and dermatomyositis are systemic inflammatory diseases with unknown etiology and prognosis. Pulmonary involvement is increasingly recognized to be a major complication and a common cause of morbidity and mortality in these diseases. Thus a thorough pulmonary evaluation is necessary to permit appropriate management. There are three categories of pulmonary complications in myositis: aspiration pneumonia, hypoventilation, and interstitial lung disease (ILD). ILD is a frequent pulmonary complication in patients with myositis, and respiratory symptoms are not reliable signs for diagnosis. The strongest predictive factor for ILD in patients with myositis is the presence of antihistidyl transfer ribonucleic acid (tRNA) synthetase antibodies (anti-Jo-1), but ILD may also be present in patients without these autoantibodies. Therefore, all patients with polymyositis or dermatomyositis should be investigated with chest radiography, high-resolution computed tomography, and lung function tests.

Benefits of intensive resistance training in patients with chronic polymyositis or dermatomyositis

OBJECTIVE

To investigate the benefits and safety of an intensive muscular training program in patients with chronic polymyositis (PM) and dermatomyositis (DM).

METHODS

Nine patients with chronic PM or DM (median age 53 years, range 44-61) were included. Assessments of impairment (10-15 voluntary repetition maximum [VRM], the Functional Index 2 [FI-2], the Grippit, and pain rated on the Borg CR-10 scale), activity limitation (Myositis Activities Profile), and participation restriction (patients' disease impact on well-being) were performed 4 weeks prior to baseline, at baseline, and after 7 weeks of exercise. A 6-item core set of disease activity measures was administered and muscle biopsy samples of vastus lateralis were obtained at baseline and after 7 weeks of exercise. Response criteria at an individual level were set for disability and disease activity. The patients exercised 3 days per week for 7 weeks on loads allowing 10 VRM.

RESULTS

On a group level there were no significant differences between assessments at 4 weeks before baseline compared with baseline. The group improved significantly regarding 10-15 VRM and FI-2 at 7 weeks compared with baseline (P < 0.05). All patients were responders with respect to impairment and 2 were activity limitation responders whereas participation restriction remained unchanged in all. Two patients were responders with reduced disease activity and no patient had signs of increased muscle inflammation in the muscle biopsy sample after 7 weeks of exercise.

CONCLUSION

Patients with chronic, stable PM and DM can perform this intensive resistive exercise program with beneficial effects on impairment and activity limitation without increased muscle inflammation.

Association between SLE nephritis and polymorphic variants of the CRP and FcgammaRIIIa genes

OBJECTIVES

To study the relationship between clinical manifestations in systemic lupus erythematosus (SLE) with polymorphisms in suggested susceptibility genes encoding FcgammaRIIa, FcgammaRIIIa, FcgammaRIIIb, CRP and IL-1Ra.

METHODS

Genetic polymorphisms were analysed in 323 unrelated SLE patients and 200 healthy blood donors. The genotype frequencies were compared between clinical subsets of SLE patients, as well as with healthy controls. Clinical manifestations included the ACR classification criteria. Nephritis was further classified according to WHO class on renal biopsy.

RESULTS

Presence of a CRP4 A-allele was associated with SLE nephritis (P < 0.01) and inversely correlated with arthritis (P < 0.01), when comparing within the SLE group. The FcgammaRIIIa F/F genotype was also associated with nephritis (WHO class III and IV, P = 0.04 for the SLE group) and in combination with the CRP4 A-allele a stronger association was noted (P < 0.001). Furthermore, the FcgammaRIIIb NA2/NA2 genotype was associated with butterfly rash (P < 0.01). An association was found between seizures and the presence of both the FcgammaRIIa R/R and the FcgammaRIIIa F/F genotypes (P < 0.01) and an inverse correlation between serositis and the CRP4 A-allele when present together with the IL-1Ra 2-allele (P = 0.01). Furthermore, a combination of the FcgammaRIIa R/R genotype and CRP4 A-allele was associated with lymphopenia (P = 0.02) and a similar result was found for the combination of FcgammaRIIIa F/F and FcgammaRIIIb NA2/NA2 (P = 0.04).

CONCLUSIONS

Polymorphic variants of the CRP and Fcgamma-receptor genes are associated with the clinical phenotype in SLE. Our findings suggest an immune complex-mediated pathogenesis in nephritis and seizures, while development of arthritis may depend on other pathogenetic pathways.

Creatine supplements in patients with idiopathic inflammatory myopathies who are clinically weak after conventional pharmacologic treatment: Six-month, double-blind, randomized, placebo-controlled trial

OBJECTIVE

To test the hypothesis that oral creatine supplements with exercise are more effective than exercise alone in improving muscle function in patients with established dermatomyositis or polymyositis receiving chronic medical therapies who are clinically weak yet stable.

METHODS

In a 6-month, 2-center, double-blind, randomized controlled trial, patients were randomized to receive oral creatine supplements (8 days, 20 gm/day then 3 gm/day) or placebo. All patients followed a home exercise program. The primary outcome was aggregate functional performance time (AFPT), reflecting the ability to undertake high-intensity exercise. Secondary outcomes included a functional index measuring endurance and muscle bioenergetics on (31)P magnetic resonance spectroscopy ((31)P MRS). Patients were receiving stable immunosuppressive treatment and/or corticosteroids.

RESULTS

A total of 37 patients with polymyositis or dermatomyositis were randomized (19 to creatine, 18 to placebo); 29 completed 6 months. Intent-to-treat analyses demonstrated that AFPT improved significantly at 6 months with creatine (median decrease 13%, range -32-8%) compared with placebo (median decrease 3%, range -13-16%; P = 0.029 by Mann-Whitney U test). A completer analysis also showed significant benefits from creatine (P = 0.014). The functional index improved significantly with both creatine and placebo (P < 0.05 by paired Wilcoxon's rank sum test), with a significant benefit between groups in the completer analysis only. Phosphocreatine/beta-nucleoside triphosphate ratios using MRS increased significantly in the creatine group (P < 0.05) but not in the control group. No clinically relevant adverse events were associated with creatine.

CONCLUSION

Oral creatine supplements combined with home exercises improve functional performance without significant adverse effects in patients with polymyositis or dermatomyositis. They appear safe, effective, and inexpensive.

A closer look at non-Hodgkin's lymphoma cases in a national Swedish systemic lupus erythematosus cohort: a nested case-control study

OBJECTIVE

To investigate risk factors for non-Hodgkin's lymphoma (NHL) and analyse NHL subtypes and characteristics in patients with systemic lupus erythematosus (SLE).

METHODS

A national SLE cohort identified through SLE discharge diagnoses in the Swedish hospital discharge register during 1964 to 1995 (n = 6438) was linked to the national cancer register. A nested case control study on SLE patients who developed NHL during this observation period was performed with SLE patients without malignancy as controls. Medical records from cases and controls were reviewed. Tissue specimens on which the lymphoma diagnosis was based were retrieved and reclassified according to the WHO classification. NHLs of the subtype diffuse large B cell lymphoma (DLBCL) were subject to additional immunohistochemical staining using antibodies against bcl-6, CD10 and IRF-4 for further subclassification into germinal centre (GC) or non-GC subtypes.

RESULTS

16 patients with SLE had NHL, and the DLBCL subtype dominated (10 cases). The 5-year overall survival and mean age at NHL diagnosis were comparable with NHL in the general population-50% and 61 years, respectively. Cyclophosphamide or azathioprine use did not elevate lymphoma risk, but the risk was elevated if haematological or sicca symptoms, or pulmonary involvement was present in the SLE disease. Two patients had DLBCL-GC subtype and an excellent prognosis.

CONCLUSIONS

NHL in this national SLE cohort was predominated by the aggressive DLBCL subtype. The prognosis of NHL was comparable with that of the general lymphoma population. There were no indications of treatment-induced lymphomas. Molecular subtyping could be a helpful tool to predict prognosis also in SLE patients with DLBCL.

Technology Insight: tools for research, diagnosis and clinical assessment of treatment in idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies, known collectively as myositis, are chronic diseases that cause disability, mainly from muscle weakness, despite the use of immunosuppressive therapies. An improved outcome requires increased knowledge of the key molecular pathways that cause symptoms in muscles and other organs. Technological advances offer promise for improving our understanding of disease mechanisms, and some tools will be helpful in diagnosis and the assessment of therapeutic success. The application of new tools depends on their validation in longitudinal studies using clinical outcome measures combined with assessments of molecular events in affected organs. Clinical outcome measures and definitions of improvement have been developed and validated through the International Myositis Assessment and Clinical Studies collaboration. Some imaging techniques, such as MRI and magnetic resonance spectroscopy of muscles, and high-resolution CT of lungs, can assess changes in local inflammatory activity, among many other aspects of pathology. Changes in protein and gene expression patterns in repeated biopsies from affected organs (muscle, skin and lungs) provide molecular information and allow increasingly precise disease classifications and therapeutic evaluation, but are to date only research tools. This Review focuses on advances in diagnostic and outcome tools and their roles in clinical practice and clinical research in patients with polymyositis and dermatomyositis.

Limited effects of high-dose intravenous immunoglobulin (IVIG) treatment on molecular expression in muscle tissue of patients with inflammatory myopathies

OBJECTIVES

The study was conducted with the aim of achieving an improved understanding of the molecular mechanisms of high-dose intravenous immunoglobulin (IVIG) in inflammatory myopathies by investigating the effects on muscle function and immunological molecules in skeletal muscle of polymyositis (PM), dermatomyositis (DM) and inclusion body myositis (IBM) patients.

METHODS

Thirteen treatment-resistant patients, 6 PM, 4 DM, 2 IBM and 1 juvenile DM, were treated with 2 g/kg of IVIG, three times at monthly intervals. Functional Index in Myositis and serum creatinine kinase (CK) levels were determined, and muscle biopsies were performed before treatment and after the third IVIG infusion. Immunological molecules were also studied in biopsies taken 24-48 h after the first infusion.

RESULTS

Improved muscle function was observed in three patients (1 PM, 1 DM and 1 IBM) and CK levels decreased in five. T cells, macrophages, major histocompatibility complex (MHC) class I antigen on muscle fibres, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression and membranolytic attack complex (MAC) deposits on capillaries were present to an equal degree in biopsies before and after IVIG treatment. No correlation between the clinical response and molecular changes was found.

CONCLUSIONS

The clinical effects of high-dose IVIG on muscle function in patients with refractory inflammatory active myositis did not correspond to effects on any of the investigated molecules in our study. T cells, macrophages, phenotypical changes in muscle fibres and endothelial cell activation were still present after treatment. These observations question a role for IVIG as an immune-modulating therapy in patients with inflammatory myopathies.

Immunolocalization of interleukin-1 receptors in the sarcolemma and nuclei of skeletal muscle in patients with idiopathic inflammatory myopathies

OBJECTIVE

Interleukin-1 (IL-1) acts via its receptors to induce gene expression that mediates protein synthesis involved in inflammation. Increased expression of IL-1alpha and IL-1beta in muscle tissue from patients with polymyositis and dermatomyositis has been demonstrated. It is not known whether the reciprocal IL-1 receptors are expressed in human muscle tissue. The purpose of this study was to investigate the expression of IL-1 receptors and their ligands in muscle tissue from patients with myositis and from healthy controls.

METHODS

Muscle biopsy tissues from 10 patients with polymyositis or dermatomyositis and 7 healthy control subjects were investigated by immunohistochemistry using antibodies against IL-1 receptor type I (IL-1RI), IL-1RII, IL-1alpha, IL-1beta, and IL-1 receptor antagonist (IL-1Ra). Quantification was performed by computerized image analysis, and localization of expression was determined by double staining using immunofluorescence and confocal microscopy.

RESULTS

In tissue samples from the patients, IL-1RI and IL-1RII were expressed in muscle fibers, inflammatory cells, and endothelial cells. Expression in muscle fibers was localized to the sarcolemma and nuclei. IL-1alpha was expressed in endothelial cells and inflammatory cells, whereas IL-1beta and IL-1Ra were expressed only in inflammatory cells. Expression of the two IL-1 receptors and their ligands was significantly higher in patients than in controls. IL-1 receptor expression on muscle fibers was most pronounced in the vicinity of cells expressing IL-1alpha and IL-1beta.

CONCLUSION

The increased expression of IL-1 receptor and the colocalization with reciprocal ligands in patients with myositis but not in healthy controls support the hypothesis of a crucial role of IL-1 in the pathogenesis of polymyositis and dermatomyositis.

The heart in dermatomyositis and polymyositis

Cardiovascular manifestations constitute a major cause of death in myositis. Despite this, clinically manifest cardiac involvement in polymyositis and dermatomyositis is relatively rare. In contrast, subclinical manifestations are frequently reported and are predominated by conduction abnormalities and arrhythmias detected by ECG. The most frequently reported clinically overt manifestations are congestive heart failure, conduction abnormalities, that may lead to complete heart block, and coronary artery disease. The underlying pathophysiological mechanisms that may cause cardiac manifestations involve myocarditis and coronary artery disease as well as involvement of the small vessels of the myocardium.

Genetically determined imbalance between serum levels of tumour necrosis factor (TNF) and interleukin (IL)-10 is associated with anti-Jo-1 and anti-Ro52 autoantibodies in patients with poly- and dermatomyositis

Our aim was to investigate presence of tumour necrosis factor (TNF) and interleukin (IL)-10 in serum and their relation to different genotypes as well as to clinical and laboratory phenotypes in patients with polymyositis and dermatomyositis. In 65 patients with poly- or dermatomyositis the inflammatory cytokine balance was evaluated by the assessing absolute levels as well as the ratio between TNF and IL-10 in serum. These levels were correlated to the G-308A TNFA, G-1087A IL10 and G915C TGFB1 gene polymorphisms and haplotype frequencies, gender, autoantibody profiles and clinical manifestations. Increased serum levels of TNF and IL-10 were observed in patients compared to controls. A significantly higher TNF:IL-10 ratio was detected in female poly- and dermatomyositis patients carrying the TNF2 allele compared to female patients with the TNF1/TNF1 genotype (median+/-IQR 1.513+/-0.0.679 vs. 0.950+/-1.173, p=0.021). This ratio was also significantly higher in patients with the extended MICA5.1/TNF2/TNFa2/DRB1*03 haplotype compared to patients lacking this haplotype. A significantly higher TNF:IL-10 ratio was recorded in sera of patients with anti-Ro52 (1.513+/-1.275 and 1.276+/-0.671, positive vs. negative, p=0.010) antibodies and in women with anti-Jo-1 (1.919+/-0.918 and 1.281+/-0.790, positive vs. negative, p=0.041). Our data suggest that a genetically programmed cytokine imbalance exists in patients with poly- or dermatomyositis and that this imbalance is related to the presence of disease-associated autoantibodies.

Signs of inflammation in both symptomatic and asymptomatic muscles from patients with polymyositis and dermatomyositis

OBJECTIVES

To determine whether muscle weakness is correlated with inflammation, expression of interleukin 1alpha (IL1alpha) and major histocompatibility complex (MHC) class I and II antigens on muscle fibres.

METHODS

Biopsy specimens from clinically symptomatic (proximal muscles) and asymptomatic (all distal but two proximal) muscles in eight patients with polymyositis, three patients with dermatomyositis and six healthy controls were analysed by immunohistochemistry for the presence of T cells and macrophages, and expression of IL1alpha and of MHC class I and II antigens.

RESULTS

were evaluated by conventional light microscopy and by computerised image analysis. Results: Inflammatory infiltrates with T cells and macrophages were observed to an equal degree in both symptomatic and asymptomatic muscle. The numbers of capillaries with IL1alpha expression were significantly higher (p<0.05) in the symptomatic and asymptomatic muscles of patients than in controls. The total IL1alpha expression per tissue section assessed by computerised image analysis was significantly higher in symptomatic muscles but not in asymptomatic muscles compared with that in controls. Neither the number of IL1alpha-positive capillaries nor the total IL1alpha expression differed significantly between symptomatic and asymptomatic muscles. Expression of MHC class I and II antigens on muscle fibres was detected in both symptomatic and asymptomatic muscles but rarely in healthy controls.

CONCLUSIONS

Presence of inflammatory infiltrates, T cells and macrophages, and expression of MHC class I and II antigens and of IL1alpha on muscle fibres were independent of clinical symptoms, and were present to an equal degree in both proximal and distal muscles. Thus, other factors seem to determine the development of clinical symptoms. One such factor could be variations in physical demands.