Objectives: To estimate the prevalence and predictors of interstitial lung disease in newly diagnosed polymyositis and dermatomyositis. Methods: A prospective study in which consecutive patients with newly diagnosed poly-and dermatomyositis, regardless of clinical symptoms of pulmonary disease, were investigated with chest x ray, high resolution computed tomography (HRCT), pulmonary function tests, and biochemical and autoantibody analysis. Patients with inclusion body myositis, malignancy, other defined inflammatory connective tissue diseases (CTDs), or antibody profile indicating other CTDs were excluded. Results: Between March 1998 and September 2000, 26 new cases of poly-or dermatomyositis were diagnosed; 17 of those patients were included in the study. Interstitial lung disease (ILD), defined as radiological signs on chest x ray examination/HRCT or restrictive ventilatory defect, were found in 11 (65%) patients and were more common in men than in women. Arthritis and occurrence of anti-Jo-1 antibodies were found more often in patients with ILD than in those without. There was no statistically significant association between respiratory symptoms, other serological or laboratory variables and ILD. Conclusions: ILD is a common early manifestation in patients with poly-and dermatomyositis and is not always related to clinical symptoms. Chest x ray examination, HRCT, pulmonary function tests, and analysis of anti-Jo-1 antibodies should be included in the initial investigation of patients with myositis regardless of respiratory symptoms. P olymyositis (PM) and dermatomyositis (DM) are systemic inflammatory disorders with unknown aetiology and pathogenesis. They mainly affect striated muscles, resulting in proximal muscle weakness. However, other organ systems, including the lungs, may be affected, and pulmonary complications are associated with high morbidity and mortality.

Objectives To determine prevalence and co-existence of myositis specific autoantibodies (MSAs) and myositis associated autoantibodies (MAAs) and associated clinical characteristics in a large cohort of idiopathic inflammatory myopathy (IIM) patients. Methods Adult patients with confirmed IIM recruited to the EuroMyositis registry (n = 1637) from four centres were investigated for the presence of MSAs/MAAs by radiolabelled-immunoprecipitation, with confirmation of anti -MDA5 and anti -NXP2 by ELISA. Clinical associations for each autoantibody were calculated for 1483 patients with a single or no known autoantibody by global linear regression modelling. Results MSAs/MAAs were found in 61.5% of patients, with 84.7% of autoantibody positive patients having a sole specificity, and only three cases (0.2%) having more than one MSA. The most frequently detected autoantibody was anti -Jo-1 (18.7%), with a further 21 specificities each found in 0.2–7.9% of patients. Autoantibodies to Mi-2, SAE, TIF1, NXP2, MDA5, PMScl and the non-Jo-1 tRNA-synthetases were strongly associated (p < 0.001) with cutaneous involvement. Anti -TIF1 and anti -Mi-2 positive patients had an increased risk of malignancy (OR 4.67 and 2.50 respectively), and anti -SRP patients had a greater likelihood of cardiac involvement (OR 4.15). Interstitial lung disease was strongly associated with the anti -tRNA synthetases, anti -MDA5, and anti -U1RNP/Sm. Overlap disease was strongly associated with anti -PMScl, anti -Ku, anti -U1RNP/Sm and anti -Ro60. Absence of MSA/MAA was negatively associated with extra-muscular manifestations. Conclusions Myositis autoantibodies are present in the majority of patients with IIM and identify distinct clinical subsets. Furthermore, MSAs are nearly always mutually exclusive endorsing their credentials as valuable disease biomarkers.

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.

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.

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+CD28null and CD8+CD28null 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 CD28null 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+CD28null and CD8+CD28null T cells in patients with dermatomyositis and polymyositis. Muscle-infiltrating CD28null 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+CD28null and CD8+CD28null 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 CD28null 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.

IntroductionThis randomized, controlled study on patients with polymyositis or dermatomyositis was based on three hypotheses: patients display impaired endurance due to reduced aerobic capacity and muscle weakness, endurance training improves their exercise performance by increasing the aerobic capacity, and endurance training has general beneficial effects on their health status.MethodsIn the first part of this study, we compared 23 patients with polymyositis or dermatomyositis with 12 age- and gender-matched healthy controls. A subgroup of patients were randomized to perform a 12-week endurance training program (exercise group, n = 9) or to a non-exercising control group (n = 6). We measured maximal oxygen uptake (VO2 max) and the associated power output during a progressive cycling test. Endurance was assessed as the cycling time to exhaustion at 65% of VO2 max. Lactate levels in the vastus lateralis muscle were measured with microdialysis. Mitochondrial function was assessed by measuring citrate synthase (CS) and β-hydroxyacyl-CoA dehydrogenase (β-HAD) activities in muscle biopsies. Clinical improvement was assessed according to the International Myositis Assessment and Clinical Studies Group (IMACS) improvement criteria. All assessors were blinded to the type of intervention (that is, training or control).ResultsExercise performance and aerobic capacity were lower in patients than in healthy controls, whereas lactate levels at exhaustion were similar. Patients in the exercise group increased their cycling time, aerobic capacity and CS and β-HAD activities, whereas lactate levels at exhaustion decreased. Six of nine patients in the exercise group met the IMACS improvement criteria. Patients in the control group did not show any consistent changes during the 12-week study.ConclusionsPolymyositis and dermatomyositis patients have impaired endurance, which could be improved by 12 weeks of endurance training. The clinical improvement corresponds to increases in aerobic capacity and muscle mitochondrial enzyme activities. The results emphasize the importance of endurance exercise in addition to immunosuppressive treatment of patients with polymyositis or dermatomyositis.Trial registrationClinicalTrials.gov: NCT01184625

Objective. To determine the effects of a 12-week endurance exercise program on health, disability, VO 2 max, and disease activity in a multicenter randomized controlled trial in patients with established polymyositis (PM) and dermatomyositis (DM), and to evaluate health and disability in a 1-year open extension study.

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/␤-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.