Y. Allenbach

Long-term observational study of sporadic inclusion body myositis

We describe a long-term observational study of a large cohort of patients with sporadic inclusion body myositis and propose a sporadic inclusion body myositis weakness composite index that is easy to perform during a clinic. Data collection from two groups of patients (Paris and Oxford) was completed either during a clinic visit (52%), or by extraction from previous medical records (48%). One hundred and thirty-six patients [57% males, 61 (interquartile range 55-69) years at onset] were included. At the last visit all patients had muscle weakness (proximal British Medical Research Council scale <3/5 in 48%, distal British Medical Research Council scale <3/5 in 40%, swallowing problems in 46%). During their follow-up, 75% of patients had significant walking difficulties and 37% used a wheelchair (after a median duration from onset of 14 years). The sporadic inclusion body myositis weakness composite index, which correlated with grip strength (correlation coefficient: 0.47; P < 0.001) and Rivermead Mobility Index (correlation coefficient: 0.85; P < 0.001), decreased significantly with disease duration (correlation coefficient: -0.47; P < 0.001). The risk of death was only influenced by older age at onset of first symptoms. Seventy-one (52%) patients received immunosuppressive treatments [prednisone in 91.5%, associated (in 64.8%) with other immunomodulatory drugs (intravenous immunoglobulins, methotrexate or azathioprine) for a median duration of 40.8 months]. At the last assessment, patients who had been treated were more severely affected on disability scales (Walton P = 0.007, Rivermead Mobility Index P = 0.004) and on the sporadic inclusion body myositis weakness composite index (P = 0.04). The first stage of disease progression towards handicap for walking was more rapid among patients receiving immunosuppressive treatments (hazard ratio = 2.0, P = 0.002). This study confirms that sporadic inclusion body myositis is slowly progressive but not lethal and that immunosuppressive treatments do not ameliorate its natural course, thus confirming findings from smaller studies. Furthermore, our findings suggest that immunosuppressant drug therapy could have modestly exacerbated progression of disability. The sporadic inclusion body myositis weakness composite index might be a valuable outcome measure for future clinical trials, but requires further assessment and validation.

Anti-HMGCR Autoantibodies in European Patients With Autoimmune Necrotizing Myopathies: Inconstant Exposure to Statin

AbstractNecrotizing autoimmune myopathy (NAM) is a group of acquired myopathies characterized by prominent myofiber necrosis with little or no muscle inflammation. Recently, researchers identified autoantibodies (aAb) against 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) in patients with NAM, especially in statin-exposed patients. Here we report what is to our knowledge the first European cohort of patients with NAM.The serum of 206 patients with suspicion of NAM was tested for detection of anti-HMGCR aAb using an addressable laser bead immunoassay. Forty-five patients were found to be anti-HMGCR positive. Their mean age was 48.9 ± 21.9 years and the group was predominantly female (73.3%). Statin exposure was recorded in 44.4% of patients. Almost all patients had a muscular deficit (97.7%), frequently severe (Medical Research Council [MRC] 5 ⩽3 in 75.5%). Subacute onset (<6 mo) was noted for most of them (64.4%). Nevertheless, 3 patients (6.6%) had a slowly progressive course over more than 10 years. Except for weight loss (20%), no extramuscular sign was observed. The mean CK level was high (6941 ± 8802 IU/L) and correlated with muscle strength evaluated by manual muscle testing (r = −0.37, p = 0.03). Similarly, anti-HMGCR aAb titers were correlated with muscular strength (r = −0.31; p = 0.03) and CK level (r = 0.45; p = 0.01). Mean duration of treatment was 34.1 ± 40.8 months, and by the end of the study no patient had been able to stop treatment.This study confirms the observation and description of anti-HMGCR aAb associated with NAM. The majority of patients were statin naive and needed prolonged treatments. Some patients had a dystrophic-like presentation. Anti-HMGR aAb titers correlated with CK levels and muscle strength, suggesting their pathogenic role.

Interleukin-21 modulates Th1 and Th17 responses in giant cell arteritis

OBJECTIVE Giant cell arteritis (GCA) is a large-vessel vasculitis of unknown origin. Recent findings indicate that at least 2 separate lineages of CD4+ T cells, Th1 and Th17 cells, participate in vascular inflammation. The pathways driving these T cell differentiations are incompletely understood, but may provide novel therapeutic targets. This study was undertaken to identify cytokines involved in the pathogenesis of GCA. METHODS Thirty GCA patients fulfilling the American College of Rheumatology criteria, with active disease or disease in remission, and 30 age-matched controls were included. Levels of 27 cytokines were determined in culture supernatants, and flow cytometric analysis of peripheral blood mononuclear cells (PBMCs) and immunohistochemical analysis of temporal artery samples were performed. RESULTS Multiparametric analysis of cytokines produced by PBMCs associated with GCA disease activity identified a signature involving interleukin-2 receptor (IL-2R), IL-12, interferon-γ (IFNγ), IL-17A, IL-21, and granulocyte-macrophage colony-stimulating factor (GM-CSF). An expansion of Th1 and Th17 cells and a decrease in Treg cells were observed in the peripheral blood of patients with active GCA. An expansion of IL-21-producing CD4+ T cells was also observed in patients with active GCA and correlated positively with Th17 and Th1 cell expansion. Immunohistochemical analysis revealed IFNγ, IL-17A, and IL-21 expression within inflammatory infiltrates. Stimulation of purified CD4+ T cells with IL-21 increased Th1 and Th17 cell frequencies and decreased FoxP3 expression. In contrast, blockade of IL-21 using IL-21R-Fc markedly decreased the production of IL-17A and IFNγ and increased FoxP3 expression. CONCLUSION Our findings indicate that IL-21 plays a critical role in modulating Th1 and Th17 responses and Treg cells in GCA, and might represent a potential target for novel therapy.

A phase I trial of adeno-associated virus serotype 1-γ-sarcoglycan gene therapy for limb girdle muscular dystrophy type 2C.

γ-Sarcoglycanopathy or limb girdle muscular dystrophy type 2C is an untreatable disease caused by autosomal recessively inherited mutations of the γ-sarcoglycan gene. Nine non-ambulatory patients (two males, seven females, mean age 27 years; range 16-38 years) with del525T homozygous mutation of the γ-sarcoglycan gene and no γ-sarcoglycan immunostaining on muscle biopsy were divided into three equal groups to receive three escalating doses of an adeno-associated virus serotype 1 vector expressing the human γ-sarcoglycan gene under the control of the desmin promoter, by local injection into the extensor carpi radialis muscle. The first group received a single injection of 3 × 10(9) viral genomes in 100 µl, the second group received a single injection of 1.5 × 10(10) viral genomes in 100 µl, and the third group received three simultaneous 100-µl injections at the same site, delivering a total dose of 4.5 × 10(10) viral genomes. No serious adverse effects occurred during 6 months of follow-up. All nine patients became adeno-associated virus serotype 1 seropositive and one developed a cytotoxic response to the adeno-associated virus serotype 1 capsid. Thirty days later, immunohistochemical analysis of injected-muscle biopsy specimens showed γ-sarcoglycan expression in all three patients who received the highest dose (4.7-10.5% positively stained fibres), while real-time polymerase chain reaction detected γ-sarcoglycan messenger RNA. In one patient, γ-sarcoglycan protein was detected by western blot. For two other patients who received the low and intermediate doses, discrete levels of γ-sarcoglycan expression (<1% positively stained fibres) were also detectable. Expression of γ-sarcoglycan protein can be induced in patients with limb girdle muscular dystrophy type 2C by adeno-associated virus serotype 1 gene transfer, with no serious adverse effects.

Role of Regulatory T Cells in a New Mouse Model of Experimental Autoimmune Myositis

Polymyositis is a rare and severe inflammatory muscle disorder. Treatments are partially efficacious but have many side effects. New therapeutic approaches must be first tested in a relevant animal model. Regulatory CD4+CD25+ T cells (Tregs) have been rediscovered as a pivotal cell population in the control of autoimmunity, but the connection between polymyositis and Tregs is currently unknown. To develop a reproducible experimental autoimmune myositis model of polymyositis, mice were immunized once a week for 3 weeks with 1 mg of partially purified myosin emulsified in complete Freunds adjuvant. All mice injected with myosin and complete Freunds adjuvant developed myositis. The infiltrates were composed of CD4(+) and CD8(+) cells, as well as macrophages, but did not contain B lymphocytes. In mice that were depleted of Tregs, the myositis was more severe, as determined by quantitative scoring of muscle inflammation (2.36 +/- 0.9 vs. 1.64 +/- 0.8, P = 0.019). In contrast, injection of in vitro expanded polyclonal Tregs at the time of immunization significantly improved the disease (quantitative score of inflammation 0.87 +/- 1.06 vs. 2.4 +/- 0.67, P = 0.047). Transfer of sensitized or CD4(+)-sorted cells from the lymph nodes of experimental autoimmune myositis mice induced myositis in naïve, irradiated, recipient mice. Thus, experimental autoimmune myositis is a reproducible, transferable disease in mice, both aggravated by Treg depletion and improved by polyclonal Treg injection.

Acquired necrotizing myopathies.

Purpose of review Necrotizing myopathy exhibits a specific histological pattern, characterized by significant necrosis, with simultaneous muscle fiber regeneration, but without or with little inflammation. This histological pattern may be observed in acquired myopathies but also in muscular dystrophy. Acquired necrotizing myopathy can be secondary to drugs or toxics agents, and if not, autoimmune mechanisms have to be suspected. Necrotizing autoimmune myopathy (NAM) is now recognized as a subgroup of idiopathic inflammatory myopathies. This review aims to further describe the different acquired myopathies, with special focus on NAM since specific autoantibodies have been discovered. Recent findings Usually, acquired myopathy has an acute onset, but a slower progression may sometimes be observed that could lead to erroneous diagnosis of muscular dystrophy. NAM may be associated with specific autoantibodies against signal recognition particle, or, as more recently described, against 3-hydroxy-3-methylglutaryl-coenzyme A reductase, especially in statin-exposed patients. Their presence permits affirmation that muscular necrosis is immune-mediated. The antibody titer is correlated to the disease activity. Summary NAMs are now considered as a new entity, treatable by immunosuppressants, and should not be misdiagnosed as a muscular dystrophy.

Antisynthetase Syndrome with Anti-Jo1 Antibodies in 48 Patients: Pulmonary Involvement Predicts Disease-modifying Antirheumatic Drug Use

Objective. To analyze the characteristics, outcomes, and predictive factors of disease-modifying antirheumatic drug (DMARD) use in 48 patients with antisynthetase syndrome [characterized by myositis, interstitial lung disease (ILD), arthritis, Raynaud’s phenomenon (RP), and/or mechanic’s hands] and the presence of anti-histidyl-transfer RNA synthetase (anti-Jo1) autoantibodies. Methods. Forty-eight patients (33 women, 15 men) who were anti-Jo1-positive referred to one center between 1998 and 2008 were analyzed retrospectively. Results. The median age of disease onset was 43 years [interquartile range (IQR) 33–53 yrs]. The median followup was 5 years (IQR 2–8 yrs). At diagnosis, 81% of patients presented with myositis, 80% ILD, 77% arthralgia, 48% RP, and 21% mechanic’s hands. During the followup, 14 patients (29%) had no need for DMARD, while 34 (71%) required DMARD. Patients with mechanic’s hands (p = 0.02) and higher creatine phosphokinase at diagnosis (median 6070 IU/l vs 1121 IU/l; p = 0.002) were more likely to need DMARD. ILD, noted on computed tomography scan by a nonspecific interstitial pneumonia score, was lower in the group of patients with no DMARD need (4 vs 7; p = 0.04). Twenty patients (44%) presented with a pulmonary aggravation (worsening of radiologic score of ILD and/or pulmonary function test results) leading to DMARD use. Nonspecific interstitial pneumonia score (7 vs 5; p = 0.05) and total lung volume (57.5% vs 70%; p = 0.02) values predicted pulmonary aggravation. Conclusion. Our study outlines the burden of chest involvement for the prognosis of antisynthetase syndrome in terms of patients’ requirement for DMARD therapy.

Nuclear actin aggregation is a hallmark of anti-synthetase syndrome–induced dysimmune myopathy

Objective: To analyze antisynthetase syndrome–associated myositis by modern myopathologic methods and to define its place in the spectrum of idiopathic inflammatory myopathies (IIMs). Methods: Skeletal muscle biopsies from antisynthetase syndrome–associated myositis and other IIMs from different institutions worldwide were analyzed by histopathology, quantitative PCR, and electron microscopy. Results: Myonuclear actin filament inclusions were identified as a unique morphologic hallmark of antisynthetase syndrome–associated myositis. Nuclear actin inclusions were never found in dermatomyositis, polymyositis, sporadic inclusion body myositis, autoimmune necrotizing myopathy associated with signal recognition particle or 3-hydroxy-3-methylglutaryl-coenzyme A reductase autoantibodies, or nonspecific myositis associated with other systemic diseases, harboring myositis-associated autoantibodies, and presenting myofiber necrosis. We show that molecules involved in actin filament formation and actin shuttling mechanisms are altered in antisynthetase syndrome, and may thus be involved in pathologic myonuclear actin aggregation. In addition, we have identified a typical topographic distribution of necrotic myofibers predominantly located at the periphery of muscle fascicles accompanied by inflammation and destruction of the perimysial connective tissue. Conclusion: Antisynthetase syndrome–associated myositis is characterized by distinctive myonuclear actin filament inclusions, including rod formations and a typical necrotizing perimysial myositis. This supports the hypothesis that antisynthetase syndrome–associated myositis is unique and should not be grouped among dermatomyositis, polymyositis, sporadic inclusion body myositis, necrotizing autoimmune myositis, or nonspecific myositis. Classification of evidence: This study provides Class II evidence that for patients with IIMs, the presence of myonuclear actin filament inclusions accurately identifies patients with antisynthetase syndrome–associated myositis (sensitivity 81%, specificity 100%).

Anti-HMGCR antibodies as a biomarker for immune-mediated necrotizing myopathies: A history of statins and experience from a large international multi-center study

In an effort to find naturally occurring substances that reduce cholesterol by inhibiting 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), statins were first discovered by Endo in 1972. With the widespread prescription and use of statins to decrease morbidity from myocardial infarction and stroke, it was noted that approximately 5% of all statin users experienced muscle pain and weakness during treatment. In a smaller proportion of patients, the myopathy progressed to severe morbidity marked by proximal weakness and severe muscle wasting. Remarkably, Mammen and colleagues were the first to discover that the molecular target of statins, 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), is an autoantibody target in patients that develop an immune-mediated necrotizing myopathy (IMNM). These observations have been confirmed in a number of studies but, until today, a multi-center, international study of IMNM, related idiopathic inflammatory myopathies (IIM), other auto-inflammatory conditions and controls has not been published. Accordingly, an international, multi-center study investigated the utility of anti-HMGCR antibodies in the diagnosis of statin-associated IMNM in comparison to different forms of IIM and controls. This study included samples from patients with different forms of IIM (n=1250) and patients with other diseases (n=656) that were collected from twelve sites and tested for anti-HMGCR antibodies by ELISA. This study confirmed that anti-HMGCR autoantibodies, when found in conjunction with statin use, characterize a subset of IIM who are older and have necrosis on muscle biopsy. Taken together, the data to date indicates that testing for anti-HMGCR antibodies is important in the differential diagnosis of IIM and might be considered for future classification criteria.

Th1 response and systemic treg deficiency in inclusion body myositis.

Objective Sporadic inclusion body myositis (sIBM), the most frequent myositis in elderly patients, is characterized by the presence muscle inflammation and degeneration. We aimed at characterizing immune responses and regulatory T cells, considered key players in the maintenance of peripheral immune tolerance, in sIBM. Methods Serum and muscle tissue levels of 25 cytokines and phenotype of circulating immune cells were measured in 22 sIBM patients and compared with 22 healthy subjects. Cytokine data were analysed by unsupervised hierarchical clustering and principal components analysis. Results Compared to healthy controls, sIBM patients had increased levels of Th-1 cytokines and chemokines such as IL-12 (261±138 pg/mL vs. 88±19 pg/mL; p<0.0001), CXCL-9 (186±12 pg/mL vs. 13±7 pg/mL; p<0.0001), and CXCL-10 (187±62 pg/mL vs. 13±6 pg/mL; p<0.0001). This was associated with an increased frequency of CD8+CD28− T cells (45.6±18.5% vs. 13.5±9.9%; p<0.0001), which were more prone to produce IFN-γ (45.6±18.5% vs. 13.5±9.9%; p<0.0001). sIBM patients also had a decreased frequency of circulating regulatory T cells (CD4+CD25+CD127lowFOXP3+, 6.9±1.7%; vs. 5.2±1.1%, p = 0.01), which displayed normal suppressor function and were also present in affected muscle. Conclusion sIBM patients present systemic immune activation with Th1 polarization involving the IFN-γ pathway and CD8+CD28− T cells associated with peripheral regulatory T cell deficiency.