Polymyositis: is there anything left? A retrospective diagnostic review from a tertiary myositis centre

OBJECTIVE

The current classification criteria for idiopathic inflammatory myopathy (IIM) retain PM as a major disease subgroup. However, evolution in the understanding of IIM has suggested that many of these patients could be better described as having an alternative diagnosis. In the present study, we apply the latest understanding of IIM subtyping to retrospectively review PM diagnoses in a large cohort of IIM patients.

METHODS

Within a previously reported cohort of 255 patients from a UK tertiary myositis clinic, 37 patients classified as PM according to both the EULAR/ACR IIM criteria and expert opinion were identified. Clinical data and complementary tests were reviewed, and consensus decisions regarding final classification were reached in each case.

RESULTS

Nine (9/37, 24.3%) patients remained classified as PM, 3.5% (9/255) of the original cohort; these PM patients were seronegative for myositis antibodies, responsive to immunosuppression, and in 4/7 (57.1%) patients where muscle biopsy was performed had HLA-1 upregulation and endomysial inflammatory infiltrates. Immune-mediated necrotizing myopathy (5/37, 13.5%) and connective tissue disease overlap myositis (7/37, 19%) were the main alternative diagnoses. The remaining patients were diagnosed as: unspecified myopathy (6/37, 16%), dermatomyositis (2/37, 5%), cancer-associated myopathy (3/37, 8.1%), and non-inflammatory myopathy (1/37, 3%, myofibrillar myopathy). Four patients (4/37, 10%) had insufficient data available to confidently reclassify.

CONCLUSION

Our study confirms that PM can now be considered a rare IIM subgroup. A thorough examination, complete myositis autoantibody panel, and careful interpretation of the biopsy results is recommended to confirm the correct IIM sub-type.

Multiple neurological manifestations in a patient with systemic lupus erythematosus and anti-NXP2-positive myositis: A case report

RATIONALE

Systemic lupus erythematosus (SLE) is a complex autoimmune inflammatory disease that frequently affects various organs. Neuropsychiatric manifestations in SLE patients, known as neuropsychiatric SLE, are clinically common. However, the principal manifestation of cranial neuropathy in patients with SLE and comorbidities is relatively rare.

PATIENT CONCERNS

In this report, we describe a 51-year-old Chinese woman who was admitted with a chief complaint of chronic-onset facial paresthesia, dysphagia, and choking cough when drinking water, accompanied by slurred speech, salivation, and limb weakness. The blood autoantibody test results showed that many SLE-associated antibodies were positive. Meanwhile, anti-nuclear matrix protein 2 (NXP2) antibody was strongly positive in the idiopathic inflammatory myopathy (IIM) spectrum test from the serum. Muscle biopsy indicated inflammatory infiltration of the muscle fiber stroma.

DIAGNOSES

Taking into account the clinical manifestations and laboratory tests of the present case, the diagnosis of SLE and probable IIM was established.

INTERVENTIONS

Corticosteroids and additional gamma globulin were administered and the clinical symptoms were relieved during the treatment process.

OUTCOMES

Unfortunately, the patient experienced sudden cardiac and respiratory arrest. Multiple system dysfunctions exacerbated disease progression, but in the present case, we speculated that myocardial damage resulting from SLE could explain why she suddenly died.

LESSONS

To our knowledge, multiple neurological manifestations in patients with SLE and anti-NXP2-positive myositis are rare. Note that SLE is still a life-threatening disease that causes multiple system dysfunctions, which requires increasing attention.

Apoptosis in idiopathic inflammatory myopathies with partial invasion; a role for CD8+ cytotoxic T cells?

Polymyositis and inclusion body myositis are idiopathic inflammatory myopathies, with a pathology characterized by partial invasion of non-necrotic muscle fibres by CD8+ cytotoxic T-cells, leading to fibre degeneration. Although the main effector pathway of CD8+ T-cells is to induce apoptosis of target cells, it has remained unclear if apoptosis occurs in these diseases, and if so, if it is mediated by CD8+ T-cells. In consecutive biopsy sections from 10 patients with partial invasion, muscle fibres and inflammatory cells were assessed by immunohistochemistry and apoptotic nuclei by the TUNEL assay. Analysis of muscle fibre morphology, staining pattern and quantification were performed on digital images, and they were compared with biopsies from 10 dermatomyositis patients and 10 controls without muscle disease. Apoptotic myonuclei were found in muscle with partial invasion, but not in the invaded fibres. Fibres with TUNEL positive nuclei were surrounded by CD8+ T-cells, granzyme B+ cells and macrophages, but lacked FAS receptor expression. In contrast, apoptotic myonuclei were rare in dermatomyositis and absent in controls. The findings confirm that apoptosis occurs in idiopathic inflammatory myopathies and support that it is mediated by CD8+ cytotoxic T- cells, acting in parallel to the process of partial invasion.

[Clinical value of myositis antibodies in patients with connective tissue disease-associated interstitial lung diseases]

Objective: To investigate the clinical significance of detection of myositis-specific antibodies (MSAs) and myositis-associated antibodies (MAAs) in patients with connective tissue disease-associated interstitial lung diseases (CTD-ILD). Methods: Serum samples of 120 patients with CTD-ILD admitted to the Department of Respiratory, Affiliated Drum Tower Hospital of Nanjing University Medical College from December 2016 to April 2018 were collected for analysis. The patients included 45 with polymyositis/dermatomyositis (PM/DM), 36 with Sjogren's syndrome (SS) and 39 with undifferentiated connective tissue disease (UCTD). There were 37 males and 83 females with an average age of (56±11) years. Thirty-two patients with non-CTD-ILD, 10 males and 22 females with an average age of (42±17) years, were enrolled as the control group. Euroline Autoimmune Inflammatory Myopathies 16 Ag kit was used for detecting MSAs and MAAs, and the positive rates of serum MSAs and MAAs were calculated. The antibody distribution and clinical characteristics of different groups were analyzed and compared. Results: Eighty-nine of the 120 patients with CTD-ILD were positive for MSA and/or MAA (74.2%), and the detection rates of MSAs and MAAs were 52.5% (63/120) and 61.7% (74/120) respectively. No myositis antibody was detected in the non-CTD-ILD group. The detection rates of MSAs in PM/DM-ILD group, SS-ILD group and UCTD-ILD group were 75.6% (34/45), 33.3%(12/36) and 43.6%(17/39) respectively. The total detection rate of MSAs in PM/DM group was significantly higher than that in SS group and UCTD group (χ(2)=14.53, 8.95, 0.01). The anti-ARS was the most frequent (50/120, 41.7%). The positive rates of MAAs in the three groups were 64.4%(29/45), 77.8%(28/36), 43.6%(17/39) respectively, and anti-Ro-52 accounted for 60%(72/120), and were highly correlated with MSAs such as anti-Jo-1 antibodies. Conclusion: Myositis antibody profiling should be performed in patients with ILD who were negative for conventional autoimmune antibody testing and had no CTD. In patients with SS-ILD and UCTD-ILD, the myositis antibody spectrum could detect the presence of myositis-specific antibodies and myositis-related antibodies in some patients, and its role in clinical diagnosis and treatment needed further observation.

An Anti-PM/Scl-75 Antibody-positive Japanese Woman Who Developed Inflammatory Myopathy

A 69-year-old Japanese woman presented with mild muscle weakness of the neck and symmetrical proximal parts of the upper and lower limbs. Laboratory tests, needle electromyography, and a muscle biopsy revealed inflammatory myopathy with an apparent clinical classification of polymyositis and positive findings for anti-PM/Scl-75 antibody. This antibody is rare among Japanese populations, and most Japanese patients with the antibody are not classified with the inflammatory myopathy seen in polymyositis. The muscle biopsy also showed marked necrotic and regenerative fibers. We need to collectively investigate patients with the potential to develop this disease, and to identify any unique characteristics for Asian populations, including Japanese.

Serum interleukin-17A level is associated with disease activity of adult patients with dermatomyositis and polymyositis

OBJECTIVES

To assess serum interleukin (IL)-17A levels in patients with dermatomyositis (DM) and polymyositis (PM) and correlate them with the demographic, clinical, laboratory and therapeutic data of these diseases.

METHODS

This was a cross-sectional, single-centre study that included defined DM and PM patients who were age-, gender- and ethnicity-matched to healthy individuals. Serum IL-17A analysis, as well as analysis for other cytokines (IL-6, TNFα and IFNγ), was performed by multiplex immunoassay. The disease status parameters were based on the International Myositis Assessment and Clinical Studies Group (IMACS) set scores.

RESULTS

Eighty DM, 32 PM patients and 104 healthy individuals were enrolled. Mean age of patients with DM and PM was 46.0 and 47.7, respectively, with a predominance of women and white ethnicity in both groups. Overall, clinical, laboratory, therapeutic, and current disease status were similar among patients with DM and PM. Median serum IL-17A level was higher in patients with PM and DM than the control group (0.73 vs. 0.49 vs. 0.35 pg/mL, respectively; p<0.050) and higher in PM when compared to DM (p<0.001). In DM, serum IL-17A levels were associated with cumulative cutaneous lesions, IMACS parameters, and serum IL-6 and IFNγ levels. In PM, serum IL-17A levels correlated with patients' current age, IMACS parameters and serum TNFα and IFNγ levels.

CONCLUSIONS

Serum IL-17A levels are not only increased, but also associated with disease activity in patients with DM and PM. Our data strongly suggest that IL-17A may be a biomarker of disease activity for these systemic autoimmune myopathies.

Clinical significance of myositis-specific autoantibody profiles in Japanese patients with polymyositis/dermatomyositis

Myositis-specific autoantibodies, such as anti-melanoma differentiation associated gene 5 (MDA5) and anti-anti-amino acyl-tRNA synthetases (ARS) antibodies, are associated with interstitial lung diseases (ILD), which determine the prognosis of polymyositis/dermatomyositis (PM/DM) patients. However, there is a paucity of data on the clinical correlation between anti-Sjögren syndrome-related antigen A (anti-SSA)/Ro52 antibodies in PM/DM. We investigated the prevalence of myositis-specific autoantibodies including anti-SSA/Ro52 antibody and assessed the clinical significance of these antibodies in patients with PM/DM.We retrospectively reviewed demographic data and clinical outcomes in patients with PM/DM. The study population comprised 24 patients with PM and 60 patients with DM. The presence of anti-myositis-specific antibodies (MDA5, ARS, Jo-1, SSA/Ro52) was determined by immunosorbent assay (ELISA).Anti-MDA5 antibody was detected in 18 patients with DM (n = 60). Anti-ARS/anti-SSA/Ro52 antibodies were detected in 31 and 39 patients with PM/DM (n = 84). Rapidly progressive ILD patients were mainly found in the anti-MDA5 antibody-positive DM group. During the follow-up period, 9 patients died. Kaplan-Meier analysis demonstrated that survival rates seem to be lower in DM patients with anti-MDA5 antibodies compared with those without anti-MDA5 antibodies. Furthermore, dual positivity for anti-SSA/Ro52 and anti-MDA5 antibodies was significantly higher in nonsurviving DM patients compared with survivors.Although the presence of anti-ARS or anti-MDA5 antibodies is a prognostic marker in patients with PM/DM, combined presence of anti-SSA/Ro52 and anti-MDA5 antibodies represent another marker for clinical outcome in DM patients. Our results suggest that anti-SSA/Ro52 antibody positivity in DM patients with anti-MDA5 antibody reveals a subgroup of DM patients with poor prognosis.

Frequency, mutual exclusivity and clinical associations of myositis autoantibodies in a combined European cohort of idiopathic inflammatory myopathy patients

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.

•

Myositis specific autoantibodies very rarely coexist in the one individual allowing endotypes to be more precisely defined.

•

The association of anti-TIF1 and cancer-associated myositis is confirmed with a cut-off age of over 58 years.

•

In a large combined European myositis cohort associations of anti-SRP with carditis and anti-Mi-2 with cancer have emerged.

•

Myositis associated autoantibodies are strongly associated with having myositis in association with another connective tissue disease.

Triggers of inflammatory myopathy: insights into pathogenesis

The inflammatory myopathies, which include dermatomyositis, polymyositis, and the immune-mediated necrotizing myopathies, are a heterogeneous group of autoimmune diseases that manifest with muscle, skin, or lung damage. Collectively, these autoimmune diseases result from loss of tolerance to a select group of self-antigens, although the precise mechanism through which this occurs is not known. Infection, malignancy, and certain medications including statins and the immune checkpoint inhibitors used in cancer therapy have been identified as potential immunologic triggers of the inflammatory myopathies. Some of these triggers are classically associated with specific myositis-specific autoantibodies (MSAs). The strong association between certain triggers and MSAs provides insights into how an immunologic event can lead to loss of tolerance to specific self-antigens, resulting in autoimmune disease. In this review, we discuss the proposed triggers of the inflammatory myopathies and their associations with MSAs, and provide insights into how these triggers may result in the inflammatory myopathies.

Paradoxical development of polymyositis-like autoimmunity through augmented expression of autoimmune regulator (AIRE)

Autoimmunity is prevented by the function of the autoimmune regulator [AIRE (Aire in mice)], which promotes the expression of a wide variety of tissue-restricted antigens (TRAs) from medullary thymic epithelial cells (mTECs) and from a subset of peripheral antigen-presenting cells (APCs). We examined the effect of additive expression of human AIRE (huAIRE) in a model of autoimmune diabetes in NOD mice. Unexpectedly, we observed that mice expressing augmented AIRE/Aire developed muscle-specific autoimmunity associated with incomplete maturation of mTECs together with impaired expression of Aire-dependent TRAs. This led to failure of deletion of autoreactive T cells together with dramatically reduced production of regulatory T cells in the thymus. In peripheral APCs, expression of costimulatory molecules was augmented. We suggest that levels of Aire expression need to be tightly controlled for maintenance of immunological tolerance. Our results also highlight the importance of coordinated action between central tolerance and peripheral tolerance under the common control of Aire.

Direct suppression of autoaggressive CD8+ T cells with CD80/86 blockade in CD8+ T cell-mediated polymyositis models of mice

OBJECTIVES

CD80/86 blockade to inhibit CD28 costimulation suppressed alloreactive human and murine CD4+ T cells but not alloreactive CD8+ T cells. In contrast, CD28 costimulation augments CD8+ T cell-mediated cell lysis in antigen-nonspecific stimulation. The present study was conducted to discern whether the CD80/86 blockade exerts therapeutic effects on CD8+ T cell-mediated polymyositis (PM) models of mice and whether the effects could be attributable to direct suppression of autoantigen-specific CD8+ T cells.

METHODS

C protein-induced myositis (CIM) was induced in mice with intradermal injection of C protein fragments. C protein peptide-induced myositis (CPIM), in which autoaggressive CD8+ T cells are activated without CD4+ T cell help, was induced in mice with intravenous injection of dendritic cells (DCs) loaded with CD8+ T cell-epitope peptides derived from the C protein fragment. The immunised mice were treated with CTLA4-Ig or anti-CD80 and anti-CD86 antibodies (anti-CD80/86 Abs). The muscles were evaluated histologically 21 days after the C protein immunisation or 7 days after the DC injection.

RESULTS

CIM was suppressed in the mice treated with CTLA4-Ig or anti-CD80/86 Abs administered prophylactically from the day of immunisation and therapeutically after the disease onset. CPIM was suppressed when CTLA4-Ig was administered concurrently with the DC injection.

CONCLUSIONS

The CD80/86 blockade was effective in PM models of mice. Amelioration of CPIM indicates direct suppression of CD8+ T cells by the CD80/86 blockade. CTLA4-Ig should be a potential therapeutic agent of PM and other CD8+T cell-mediated diseases by suppressing both autoantigen-specific CD4+ and CD8+ T cells.

Calcinosis in poly-dermatomyositis: clinical and laboratory predictors and treatment options

OBJECTIVES

We aimed to identify the possible clinical and laboratory predictors of calcinosis in a cohort of patients with a diagnosis of polymyositis (PM) and dermatomyositis (DM).

METHODS

We carried out a retrospective analysis of a cohort of myositis patients attending our clinic between January 2013 and May 2014.

RESULTS

74 patients (58 females, 16 males) with PM (30 cases), DM (30 cases), overlap syndrome (13 cases) and inclusion body myositis (1 case) were enrolled. Sixteen patients (21.6%) had calcinosis that occurred a mean of 43.7 months after diagnosis of PDM. At multivariate analysis, patients with calcinosis experienced longer follow-up duration (p=0.006), anti-PM/Scl (p=0.033) and anti-NXP2 (p=0.024) positivity compared to patients without calcinosis. Furthermore, anti-NXP-2 positive C+ showed a diffuse form of calcinosis from the beginning and lower frequency of respiratory tract involvement. No single drug or associations of drugs was found effective in the treatment of calcinosis.

CONCLUSIONS

A longer follow-up period of time, DM diagnosis and positivity for PM/Scl and NXP-2 could all be considered risk factors which foresee the development of calcinosis. Moreover, the positivity for antibodies to NXP-2 depicts a distinct phenotype of calcinosis with an early onset and quick widespread dissemination.

Atorvastatin-induced necrotizing autoimmune myositis: An emerging dominant entity in patients with autoimmune myositis presenting with a pure polymyositis phenotype

The general aim of this study was to evaluate the disease spectrum in patients presenting with a pure polymyositis (pPM) phenotype. Specific objectives were to characterize clinical features, autoantibodies (aAbs), and membrane attack complex (MAC) in muscle biopsies of patients with treatment-responsive, statin-exposed necrotizing autoimmune myositis (NAM). Patients from the Centre hospitalier de l'Université de Montréal autoimmune myositis (AIM) Cohort with a pPM phenotype, response to immunosuppression, and follow-up ≥3 years were included. Of 17 consecutive patients with pPM, 14 patients had a NAM, of whom 12 were previously exposed to atorvastatin (mean 38.8 months). These 12 patients were therefore suspected of atorvastatin-induced AIM (atorAIM) and selected for study. All had aAbs to 3-hydroxy-3-methylglutaryl coenzyme A reductase, and none had overlap aAbs, aAbs to signal recognition particle, or cancer. Three stages of myopathy were recognized: stage 1 (isolated serum creatine kinase [CK] elevation), stage 2 (CK elevation, normal strength, and abnormal electromyogram [EMG]), and stage 3 (CK elevation, proximal weakness, and abnormal EMG). At diagnosis, 10/12 (83%) patients had stage 3 myopathy (mean CK elevation: 7247 U/L). The presenting mode was stage 1 in 6 patients (50%) (mean CK elevation: 1540 U/L), all of whom progressed to stage 3 (mean delay: 37 months) despite atorvastatin discontinuation. MAC deposition was observed in all muscle biopsies (isolated sarcolemmal deposition on non-necrotic fibers, isolated granular deposition on endomysial capillaries, or mixed pattern). Oral corticosteroids alone failed to normalize CKs and induce remission. Ten patients (83%) received intravenous immune globulin (IVIG) as part of an induction regimen. Of 10 patients with ≥1 year remission on stable maintenance therapy, IVIG was needed in 50%, either with methotrexate (MTX) monotherapy or combination immunosuppression. In the remaining patients, MTX monotherapy or combination therapy maintained remission without IVIG. AtorAIM emerged as the dominant entity in patients with a pPM phenotype and treatment-responsive myopathy. Isolated CK elevation was the mode of presentation of atorAIM. The new onset of isolated CK elevation on atorvastatin and persistent CK elevation on statin discontinuation should raise early suspicion for atorAIM. Statin-induced AIM should be included in the differential diagnosis of asymptomatic hyperCKemia. Three patterns of MAC deposition, while nonpathognomonic, were pathological clues to atorAIM. AtorAIM was uniformly corticosteroid resistant but responsive to IVIG as induction and maintenance therapy.

Clinical features and outcomes of interstitial lung disease in anti-Jo-1 positive antisynthetase syndrome

BACKGROUND

Interstitial lung disease (ILD) is a common extra-muscular manifestation of antisynthetase (AS) syndrome. ILD prevalence is higher with anti-Jo-1 antibody positivity. Data on long-term outcomes in these patients are lacking.

METHODS

Over 15 years, we identified subjects with anti-Jo-1 positive AS syndrome and ILD. Demographics, pulmonary function testing (PFT), high-resolution computed tomography (HRCT), histopathology, and long-term survival were analyzed.

RESULTS

We identified 103 subjects (mean age 49.2 years, female predominance [70%]). The predominant myopathy was polymyositis (64%) followed by dermatomyositis (24%). In approximately half of studied subjects, AS syndrome and ILD were diagnosed within 6 months of each other. The majority had restriction on PFTs (98%). Non-specific interstitial pneumonia (NSIP) was the most common HRCT pattern (52%), followed by NSIP overlapping with organizing pneumonia (OP) (22%). Thirty-nine subjects had biopsy data. Ten-year survival was 68%. Multivariable analysis adjusted for age at ILD diagnosis, gender, FVC and DLCO, revealed that male gender (HR = 2.60, p = 0.04) and DLCO at presentation (HR = 0.94, p = 0.05) significantly predicted mortality.

CONCLUSIONS

We present a large cohort of anti-Jo-1 positive AS syndrome with ILD and note good overall survival.

Clinical Utility of an Enzyme-Linked Immunosorbent Assay for Detecting Anti-Melanoma Differentiation-Associated Gene 5 Autoantibodies

Objective

Autoantibodies to melanoma differentiation-associated gene 5 (MDA5) are specifically expressed in patients with dermatomyositis (DM) and are associated with a subset of DM patients with rapidly progressive interstitial lung disease (RP-ILD). Here, we examined the clinical utility of a newly developed enzyme-linked immunosorbent assay (ELISA) system for detecting these antibodies.

Methods

Here we developed an improved ELISA for detecting anti-MDA5 antibodies. We then performed a multicenter clinical study involving 8 medical centers and enrolled 242 adult patients with polymyositis (PM)/DM, 190 with non-PM/DM connective tissue disease (CTD), 154 with idiopathic interstitial pneumonia (IIP), and 123 healthy controls. Anti-MDA5 antibodies in the patients’ serum samples were quantified using our newly developed ELISA, and the results were compared to those obtained using the gold-standard immunoprecipitation (IP) assay. In addition, correlations between the ELISA-quantified anti-MDA5 antibodies and clinical characteristics were evaluated.

Results

In patients with PM/DM, the anti-MDA5 antibody measurements obtained from the ELISA and IP assay were highly concordant; the ELISA exhibited an analytical sensitivity of 98.2%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 99.5% (compared to the IP assay). Anti-MDA5 antibodies were detected in 22.7% of the DM patients, but not in any of the patients with PM, non-PM/DM CTD, or IIP. Clinically amyopathic DM, RP-ILD, arthritis, and fever were more prevalent in DM patients who were anti-MDA5 antibody-positive than in those who were antibody-negative (P ≤ 0.0002 for all comparisons). In addition, anti-MDA5 antibody-positive patients with RP-ILD exhibited higher antibody levels than those without RP-ILD (P = 0.006).

Conclusion

Our newly developed ELISA can detect anti-MDA5 antibodies as efficiently as the gold standard IP assay and has the potential to facilitate the routine clinical measurement of anti-MDA5 antibodies in patients who suspected to have DM.

Autoantibodies in adult patients with idiopathic inflammatory myopathies in Buenos Aires

The idiopathic inflammatory myopathies(IIM) are a heterogeneous group of diseases of the skeletal muscle. On the basis of clinical, serologic and histological differences, they are classified in dermatomyositis (DM), polymyositis (PM), inclusion body myositis and immunomediated necrotizing myopathy. Autoantibodies directed against nuclear and cytoplasmic antigens are present with variable frequencies among studies. Myositis-specific antibodies (MSAs) are useful in IIM because they contribute to the diagnosis, help to identify different clinical subsets, and have prognostic value. This study aimed to explore the frequency of autoantibodies, especially MSAs, and their relationship with clinical features in adult patients with DM, PM and overlap syndrome. Medical records were reviewed. Myositis-associated antibodies (non-specific) and MSAs (anti Jo-1, PL-7, PL-12, Mi-2 and SRP) were measured using commercial kits. Twelve patients had MSAs, an overall frequency similar to those of international series, but PL-12 and Mi-2 were more frequent than Jo-1, which is the most frequently observed elsewhere. All five patients with Mi-2 had classical DM with a favorable response to treatment. Interstitial pneumonia (n: 4) and/or treatment-refractory disease (n: 3) were found in the presence of anti-PL-12, alone or associated with anti-SRP and/or Jo-1. In conclusion, the coexistence of AEM, a rare finding, was found in three patients. The presence of MSAs aided to the diagnosis of IIM, in particular in those patients without available or conclusive biopsy results.

A CASE OF POLYMYOSITIS WITH INTERSTITIAL LUNG DISEASE ONSET

Polymyositis is an idiopathic inflammatory myopathy of unknown aetiology that affect skeletal muscles causing symmetrical, proximal muscle weakness, and also other internal organs. The investigations reveal elevated skeletal muscle enzyme levels and characteristic electromyography (EMG) and muscle biopsy findings. Pulmonary involvement in polymyositis includes respiratory muscle weakness, aspiration pneumonia, interstitial lung disease, infection and drug-induced pneumonia. We expose the case of a young woman (47 years old) who presented to the Pulmonology Clinic with fever, cough, purulent sputum, discrete myalgia, being diagnosed at that moment with interstitial lung disease and treated with antibiotics, low dose of corticosteroids and symptomatic drugs. The evolution was slowly favorable for the respiratory impairment, but the patient developed exacerbated myalgia, muscle weakness, reaching even the impossibility of maintaining orthostatism, and also joint pain. Biological investigations revealed an important hepatocytolysis syndrome and also increased levels of muscle enzyme. The hypothetical diagnosis was polymyositis and to sustain this theory it was performed a muscle biopsy. The patient was transferred afterwards to the Rheumatology Clinic, in order to perform other specific investigations. In our clinic the patient maintained elevated levels of skeletal muscle enzymes and the muscle biopsy revealed polymyositis findings. Also immunological investigations objectified the presence of Jo1 antibodies. Therefore we pleaded for the diagnosis of idiopathic polymyositis, acute form. A multidisciplinary approach is needed in order to establish an accurate diagnosis and to institute a proper treatment.

The Prevalence of Individual Histopathologic Features Varies according to Autoantibody Status in Muscle Biopsies from Patients with Dermatomyositis

OBJECTIVE

Individual dermatomyositis (DM)-associated autoantibodies are associated with distinct clinical phenotypes. This study was undertaken to explore the association of these autoantibodies with specific muscle biopsy features.

METHODS

DM subjects with a muscle biopsy reviewed at Johns Hopkins had sera screened for autoantibodies recognizing Mi-2, transcriptional intermediary factor 1-γ (TIF1-γ), NXP2, MDA5, Ro52, PM-Scl, and Jo1. We also included anti-Jo1–positive patients with polymyositis (PM) who had a biopsy read at Johns Hopkins. Analyzed histological features included perifascicular atrophy, perivascular inflammation, mitochondrial dysfunction, primary inflammation, and myofiber necrosis. Duration of disease, biopsy location, and treatment at biopsy were also analyzed.

RESULTS

We studied 91 DM and 7 anti-Jo1–positive patients with PM. In univariate analyses, TIF1-γ+ patients had more mitochondrial dysfunction (47% vs 18%; p = 0.05), NXP2+ patients had less primary inflammation (0% vs 28%; p = 0.01), Mi-2+ patients had more primary inflammation (50% vs 19%; p = 0.03), and PM-Scl+ patients had more primary inflammation (67% vs 18%; p = 0.004) than those who were negative for each autoantibody. Although reliability was limited because of small sample numbers, multivariate analysis confirmed that TIF1-γ+ patients had more mitochondrial dysfunction [prevalence ratio (PR) 2.6, 95% CI 1.0–6.5, p = 0.05] and PM-Scl+ patients had more primary inflammation (PR 5.2, 95% CI 2.0–13.4; p = 0.001) independent of disease duration at biopsy, biopsy site, and treatment at biopsy. No differences in muscle biopsy features were noted between anti-Jo1–positive patients diagnosed with DM and PM.

CONCLUSION

The prevalence of different histological features varies according to autoantibody status in DM. Muscle biopsy features are similar in anti-Jo1 patients with and without a rash.

The effect of prior corticosteroid use in muscle biopsies from patients with dermatomyositis

OBJECTIVES

The aim of this study was to evaluate the effect of prior corticosteroid (CS) use on the presence of inflammatory infiltrates (InI) in muscle biopsies from dermatomyositis (DM).

METHODS

Sixty-five muscle biopsy samples were obtained at the time of DM diagnosis. The patients were divided into the following three groups according to the degree of the InI present in the muscle biopsies: (I) minimal InI present only in an interstitial area (endomysium, perimysium) or in a perivascular area; (II) moderate InI in one or two areas of the interstitium or of the perivascular area; and (III) moderate InI throughout the interstitium or intense inflammation in at least one area of the interstitium or of the perivascular area.

RESULTS

All groups (I=17, II=16 and III=32) were comparable regarding the patient age at the time of the muscle biopsy, gender, ethnicity distribution, time interval between the muscle biopsy and the symptom onset, clinical manifestations, degree of muscle weakness, autoantibodies and serum muscle enzyme measurements (p<0.05). The median (interquartile) duration of CS use [7 (0-60), 6 (0-105) and 14 (0-30) days in groups I, II and III, respectively] and the median cumulative CS dose used [560 (0-2100), 1005 (0-2850) and 875 (0-2850) mg] were similar between the groups (p>0.05).

CONCLUSIONS

Previous CS use did not influence the presence or the degree of inflammatory infiltrates found in muscle biopsies in DM with clinical and laboratory disease activity. Therefore, muscle biopsies should be performed in this population, including patients currently undergoing CS therapy.

Does previous corticosteroid treatment affect the inflammatory infiltrate found in polymyositis muscle biopsies?

OBJECTIVES

The aim of the study was to evaluate the effect of the prior use of corticosteroids (CS) on the presence of inflammatory infiltrates (InI) in muscle biopsies of polymyositis (PM).

METHODS

We retrospectively evaluated 60 muscle biopsy samples that had been obtained at the time of the diagnosis of PM. The patients were divided into three groups according to the degree of the InI present in the muscle biopsies: (a) minimal InI present only in an interstitial area of the muscle biopsy (endomysium, perimysium) or in a perivascular area; (B) moderate InI in one or two areas of the interstitium or of the perivascular area; and (C) moderate InI throughout the interstitium or intense inflammation in at least one area of the interstitium or of the perivascular area.

RESULTS

The three groups were comparable regarding the demographic, clinical and laboratory features (p>0.05). Approximately half of the patients in each group were using CS at the time of the muscle biopsy. The median (interquartile) duration of CS use [4 (0-38), 4 (0-60) and 5 (0-60) days: groups A, B and C, respectively] and the median cumulative CS dose used [70 (0-1200), 300 (0-1470) and 300 (0-1800)mg] were similar between the groups (p>0.05).

CONCLUSIONS

Previous CS use did not influence the presence or the degree of InI found in muscle biopsies in PM with clinical and laboratory disease activity. Our study showed that muscle biopsies should be performed this population, even in individuals who have already been taking CSs.

[Anti-signal recognition particle autoantibody positive myopathy]

Idiopathic inflammatory myopathies are systemic, autoimmune diseases characterized by proximal symmetrical muscle weakness. We review the myositis-associated and myositis-specific autoantibodies, among them the anti-SRP autoantibody. Among those autoimmune myopathy cases, that are associated with autoantibodies, we can detect anti-SRP autoantibody positive myositis cases. We describe the role of signal recognition particle, its structure and role in protein biosynthesis. We review how necrotizing autoimmune myopathy is identified, and the differences from classical polymyositis. The anti-SRP titer correlates with disease activity. We present some cases to show how the disease appears in childhood and also some rare cases from the literature. Finally we present a case to draw attention to the importance of this disease.

Altered RIG-I/DDX58-mediated innate immunity in dermatomyositis

We investigated the molecular mechanisms involved in the pathogenesis of three inflammatory myopathies, dermatomyositis (DM), polymyositis (PM) and inclusion body myositis (IBM). We performed microarray experiments(†) using microdissected pathological muscle fibres from 15 patients with these disorders and five controls. Differentially expressed candidate genes were validated by immunohistochemistry on muscle biopsies, and the altered pathways were analysed in human myotube cultures. Up-regulation of genes involved in viral and nucleic acid recognition were found in the three myopathies but not in controls. In DM, retinoic acid-inducible gene 1 (RIG-I, DDX58) and the novel antiviral factor DDX60, which promotes RIG-I-mediated signalling, were significantly up-regulated, followed by IFIH1 (MDA5) and TLR3. Immunohistochemistry confirmed over-expression of RIG-I in pathological muscle fibres in 5/5 DM, 0/5 PM and 0/5 IBM patients, and in 0/5 controls. Stimulation of human myotubes with a ligand of RIG-I produced a significant secretion of interferon-β (IFNβ; p < 0.05) and up-regulation of class I MHC, RIG-I and TLR3 (p < 0.05) by IFNβ-dependent and TLR3-independent mechanisms. RIG-I-mediated innate immunity, triggered by a viral or damage signal, plays a significant role in the pathogenesis of DM, but not in that of PM or IBM.

Dermatomyositis and polymyositis: from immunopathology to immunotherapy (immunobiologics)

Idiopathic inflammatory myopathies (IIM), which include dermatomyositis (DM) and polymyositis (PM), are chronic systemic diseases associated with high morbidity and functional disability. Current treatment is based on the use of glucocorticoids and immunosuppressive drugs, but a considerable number of patients is refractory to traditional therapy. That has led to the attempted use of biologics based on the physiopathogenesis of IIM. From the immunopathological viewpoint, PM and DM differ: the former is more related to cellular immunity, while the latter, to humoral immunity. In both, however, elevated concentrations of proinflammatory interleukins (TNF, IL-1, IL-6) and increased expression of molecules related to costimulation of T lymphocytes have been described; thus, the use of biologics in those conditions seems reasonable. Considering the biologics available, open-label studies are scarce, comprising mainly case reports and series. TNF blockers have yielded conflicting results, with no evidence of good response to treatment. The anti-CD20 therapy has the most promising results. Data on T lymphocyte costimulation blockade and anti-IL-6 therapy are extremely scarce, preventing any consideration. Thus, the use of biologics in IIM still remains an unconquered frontier. Biologics may have an important role in the management of IIM refractory to conventional therapy, but further prospective studies based on objective parameters of response to treatment are needed. So far, anti-CD20 therapy seems to be the most promising treatment for refractory IIM.

[Expression of Gphaq in peripheral blood T lymphocytes of patients with polymyositis and its correlation with disease activity]

OBJECTIVE

To analyze the expression of Gaq in peripheral blood T lymphocytes of the patients with polymyositis (PM) and its correlation with disease activity evaluated by the clinical markers [manual muscle test (MMT),myositis disease activity assessment (MDAA),creatine phosphokinase (CK), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP)].

METHODS

Blood samples were obtained from 30 patients with first onset PM and 30 healthy volunteers. Peripheral blood mononuclear cells (PBMCs) from these patients were collected and CD3+ T cells from PBMCs were sorted out with magnetic beans. The mRNA and protein expression levels of Galphaq in T cells were measured by RT-PCR and Western blot. Student's unpaired 2-tailed t-test was applied to identify Galphaq expression difference between PM patients and healthy controls. Pearson's correlation between Galphaq mRNA expression of PM and clinical evaluation markers MMT, MDAA, CK, ESR or CRP was determined.

RESULTS

Compared to health control, PM patients had significantly lower expression levels of Galphaq protein and mRNA in peripheral blood CD3+ T cells (P<0. 001). Negative correlation was found between Galphaq mRNA level and MMT (r= -0. 704, P<0. 001), MDAA (r= -0. 793, P<0. 001) or CK (r= -0. 670, P<0. 001), and no correlation was found between Galphaq mRNA level and ESR or CRP.

CONCLUSION

Galphaq expression in T cells of PM is lower than that in normal control and has negative correlation with PM disease activity.

Clinical manifestations and outcome of anti-PL7 positive patients with antisynthetase syndrome

BACKGROUND

The aims of the present study were to determine both clinical manifestations and outcome of anti-PL7 patients with antisynthetase syndrome (ASS).

METHODS

The medical records of 15 consecutive anti-PL7 patients with biopsy proven ASS were retrospectively analyzed without prior selection.

RESULTS

Anti-PL7 patients exhibited polymyositis (n=14) and dermatomyositis (n=1); extra-pulmonary manifestations of ASS included: Raynaud's phenomenon (40%), mechanic's hands (33.3%), joint impairment (26.7%), pericardial effusion (20%) and esophageal/gastrointestinal involvement (20%). The outcome of myositis was as follows: remission/improvement (91.7%) and deterioration (8.3%). Fourteen patients (93.3%) experienced interstitial lung disease (ILD). ILD preceded ASS diagnosis (n=5), was identified concomitantly with ASS (n=8) and occurred after ASS diagnosis (n=1). Patients could be divided into 3 groups according to their presenting lung manifestations: acute onset of lung disease (n=1), progressive onset of lung signs (n=11) and asymptomatic patients exhibiting abnormalities consistent with ILD on PFT and HRCT-scan (n=2). No patient had resolution of ILD, whereas 64.3% and 35.7% experienced improvement and deterioration of ILD, respectively. ILD resulted in respiratory insufficiency requiring O2 therapy in 14.3% of cases. Two patients died. Predictive parameters of ILD deterioration were: DLCO<45% at ILD diagnosis and HRCT-scan pattern of usual interstitial pneumonia (UIP).

CONCLUSION

Our series mainly underscores that ILD is frequent in anti-PL7 patients, leading to high morbidity. Our study further suggests that patients with predictive factors of ILD deterioration may require more aggressive therapy, especially the group of patients with DLCO<45% at ILD diagnosis and UIP pattern on HRCT-scan.

Inflammatory myopathies in Nigerians: case series and literature review

BACKGROUND

Idiopathic Inflammatory myopathies (IIM) are rare connective tissue diseases and have been rarely reported among Nigerians:

OBJECTIVE

To study the clinical, laboratory and electromyographic characteristics of Nigerian patients with polymyositis and dermatomyositis.

METHOD

In a retrospective study, patients attending a private practice rheumatology clinic in Lagos and fulfilling the Bohan and Peter's criteria for polymyositis and dermatomyositis were examined and common causes of proximal muscle weakness were excluded. Haematological, biochemical, serological and electromyographic studies were carried out. Patients were treated with standard drugs.

RESULTS

Fourteen patients (F-13, M-1) were diagnosed with Polymyositis (PM) and Dermatomyositis (DM). Seven had probable PM, 4 with possible PM and 3 with probable DM. Mean age was 35 years (range 22-54) ESR was markedly raised mean 105/min (26-150). Muscle and liver enzymes were raised in all patients. Creatinine kinase median 1134 (29-10,166); lactic dehydrogenase median 477 (209-787); ALT 43 (19-233); AST 136 (25-725). Serology for ANF was positive in eight patients; Anti Jo1 in 1 out of 9 while Anti Mi2 was negative in all tested. EMG in 6 tested showed myopathic pattern.

CONCLUSION

Inflammatory myopathies are rare among Nigerians but a heightened awareness is needed for diagnosis and management.

Common and distinct clinical features in adult patients with anti-aminoacyl-tRNA synthetase antibodies: heterogeneity within the syndrome

Objective

To identify similarities and differences in the clinical features of adult Japanese patients with individual anti-aminoacyl-tRNA synthetase antibodies (anti-ARS Abs).

Methods

This was a retrospective analysis of 166 adult Japanese patients with anti-ARS Abs detected by immunoprecipitation assays. These patients had visited Kanazawa University Hospital or collaborating medical centers from 2003 to 2009.

Results

Anti-ARS Ab specificity included anti-Jo-1 (36%), anti-EJ (23%), anti-PL-7 (18%), anti-PL-12 (11%), anti-KS (8%), and anti-OJ (5%). These anti-ARS Abs were mutually exclusive, except for one serum Ab that had both anti-PL-7 and PL-12 reactivity. Myositis was closely associated with anti-Jo-1, anti-EJ, and anti-PL-7, while interstitial lung disease (ILD) was correlated with all 6 anti-ARS Abs. Dermatomyositis (DM)-specific skin manifestations (heliotrope rash and Gottron’s sign) were frequently observed in patients with anti-Jo-1, anti-EJ, anti-PL-7, and anti-PL-12. Therefore, most clinical diagnoses were polymyositis or DM for anti-Jo-1, anti-EJ, and anti-PL-7; clinically amyopathic DM or ILD for anti-PL-12; and ILD for anti-KS and anti-OJ. Patients with anti-Jo-1, anti-EJ, and anti-PL-7 developed myositis later if they had ILD alone at the time of disease onset, and most patients with anti-ARS Abs eventually developed ILD if they did not have ILD at disease onset.

Conclusion

Patients with anti-ARS Abs are relatively homogeneous. However, the distribution and timing of myositis, ILD, and rashes differ among patients with individual anti-ARS Abs. Thus, identification of individual anti-ARS Abs is beneficial to define this rather homogeneous subset and to predict clinical outcomes within the “anti-synthetase syndrome.”

Systemic sclerosis-polymyositis overlap syndrome associated with autoimmune hepatitis and cerebral vasculitis

Autoimmune hepatitis (AIH) is a chronic disorder characterized by persistent hepatocellular inflammation and necrosis. AIH overlap syndromes with other autoimmune diseases have been reported, including connective tissue diseases (CTD). Reports of AIH in systemic sclerosis (SSc), however, are scarce and have been particularly described in the limited SSc subtype. We report a case of systemic sclerosis-polymyositis overlap syndrome that developed AIH and subsequently, cerebral vasculitis. To our knowledge, this is the first report of such a complex mosaic of autoimmunity. We also review the literature regarding scleroderma-related AIH.

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

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

Cutting edge issues in polymyositis

Skeletal muscle is the target tissue of immunoflogistic processes in patients affected with idiopathic inflammatory myopathies (IIM). IIM are classified into three major forms: polymyositis (PM), dermatomyositis (DM), and inclusion body myositis. Recent data suggest that, in the major subsets of myositis, antigens in muscles drive a B-cell antigen-specific immune response. Moreover, some non-immunological mechanisms have been advocated. In this regard, an increased expression of Jo-1 and Mi-2 in muscle biopsies from PM and DM patients compared to normal muscle has been demonstrated; these candidate autoantigens in myositis are expressed at high levels in regenerating muscle cells rather than in mature myotubes. Myositis autoantigen upregulation has also been observed in neoplastic tissues, thus representing a potential link between cancer and autoimmunity in myositis. Myositis-specific autoantibodies (MSA) are disease markers and target intracellular proteins involved in key processes such as translocation and nuclear transcription. Myositis target antigens encompass aminoacyl-tRNA synthetases, the Mi-2 helicase/histone deacetylase protein complex, the signal recognition particle ribonucleoprotein, together with novel target antigens including p155/140, CADM-140, and SAE. Despite their high specificity for autoimmune myositis, MSA target non-muscle restricted proteins ubiquitary to all cell types, making the specific muscle involvement difficult to explain. Non-immunological mechanisms also seem to contribute to the pathogenesis of IIM; activation of endoplasmic reticulum stress response due to muscle regeneration and inflammation but independent to MHC-1 up-regulation has been recently reported in patients with myositis.

[Pathogenesis of polymyositis and dermatomyositis]

The idiopathic inflammatory myopathies, collectively called myositis, are a heterogeneous group of diseases of which polymyositis and dermatomyositis are the best known. These heterogeneous group of chronic disordes sharing the clinical symptom of muscle weakness and, in typical cases, inflammatory cell infiltrates in muscle tissue. There are four major types of idiopathic inflammatory myopathies: dermatomyositis, polymyositis, inclusion body myositis and immune-mediated necrotizing myopathies (autoimmune necrotizing myopathies). Clinical and histopatological distinctions between these conditions suggest that different pathogenic processes underline each of the inflammatory myopathies.

[Laboratory diagnostics of polymyositis/dermatomyositis]

Polymyositis/dermatomyositis is chronic systemic inflammatory disease that usually affects the skin and muscle tissue. The diagnosis of polymyositis/dermatomyositis isn't simple, and represents challenge for clinicians, it is based on the integration of results: medical history and clinical presentation, laboratory findings enzymes more or less specific to muscle tissue, myositis-specific autoantibodies and autoantibodies associated with myositis which can be found at other inflammatory connective tissue diseases without myositis, electromyography findings, and biopsy of muscle and skin. Laboratory tests contribute and assist in the diagnosis of polymyositis/dermatomyositis but they should always be evaluated in context with clinical picture and other tests and decisions about diagnosis and/or treatment are based on the integration of the results.

[Polymyositis, dematomyositis: overlap syndromes with connective tissue diseases and malignancies]

Polymyositis and Dermatomyositis are often connected with autoimmune diseases and are closely linked with specific autoantibodies. Clinical manifestations are mild in correlation with clinical picture ofmyositis related to malignancy. Pulmonary complications are main cause of mortality in overlap syndromes with autoimmune diseases. Infection, cardiovascular complications and underlying malignancy provide greater mortality risk.

[Myositis-specific autoantibodies and their clinical significance]

The idiopathic inflammatory myopathies polymyositis (PM) and dermatomyositis (DM) have historically been defined using broad clinical and pathological criteria. These conditions affect both adults and children with clinical features including muscle weakness, skin disease, internal organ involvement, and an association with cancer in adults. Using a clinical-serological approach, PM and DM can be defined into more homogeneous subsets. In recent years, myositis-specific autoantibodies (MSAs) have been better characterized and include autoantibodies to the signal-recognition particle and aminoacyl tRNA-synthetase enzymes. In addition, clinically significant novel autoantibodies -anti-p155/p140, anti-CADM-140, and others- have been described in the disease spectrum. MSAs are directed against cytoplasmic or nuclear components involved in key regulatory intracellular processes including protein synthesis, translocation, and transcription. The striking association between unique serological profiles and distinct clinical phenotypes suggests that target autoantigens may play a role in disease induction and propagation. This review reports recent progress in myositis-specific autoantigens, particularly their clinical significance.

Dermatomyositis and polymyositis: new treatment targets on the horizon

Polymyositis (PM) and dermatomyositis (DM) are rare idiopathic inflammatory myopathies (IIM) with a presumed autoimmune pathogenesis. Typical features are subacute onset, proximal, symmetric muscle weakness, elevated serum creatine kinase, and mononuclear cell infiltrates in the muscle biopsy. Strong support for an autoimmune pathogenesis comes from histopathological findings in biopsies of affected muscles. Furthermore, the association with autoantibodies supports the notion that immune-mediated inflammation is involved. PM and DM may occur in isolation or in connection with a connective tissue disease or cancer. The current treatment for IIM consists of first-line high-dose steroids and various conventional second-line treatments. Improvements in treatment for IIM are hampered by difficulties in the design of trials and the low incidence and prevalence of the disease. Cytokines and chemokines are factors involved in the inflammatory process in IIM, and are candidates for future therapeutic targets. Preliminary data with anti-tumour necrosis factor therapy are not very promising, but results of blockers of the lymphotoxin signalling pathway are to be awaited. Anti-B cell therapy may be a valuable therapeutic option for treatment of refractory IIM. The effects of anti-interferon-alpha in IIM are to be awaited, as are results of other anti-cytokine therapies and anti-chemokine therapy. Outcome measures to be used in clinical trials in II M include at present the core sets of outcome proposed by the International Myositis Assessment Clinical Study Group (IMACS).

Polymyositis associated with autoimmune hepatitis, primary biliary cirrhosis, and autoimmune thrombocytopenic purpura

We describe a 40-year-old woman with polymyositis (PM) who developed autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), and autoimmune thrombocytopenic purpura (AITP) concurrently. About 4 years earlier, she suffered from muscle weakness probably due to PM. When she visited our hospital, she had polyarthritis, myalgia, symmetrical proximal limb-muscle weakness, elevated muscle enzymes, and myogenic abnormalities on electromyogram. Pathological findings obtained by muscle biopsy showed histological findings consistent with PM. Her serum liver enzymes were also elevated. The histology obtained by liver biopsy revealed the mixture findings of chronic active hepatitis and biliary cirrhosis. As antibodies to mitochondria M2 and liver/kidney microsome type 1 (LKM-1) were present, we concluded her liver disease was due to an overlap of AIH and PBC. Furthermore, purpura on the legs with thrombocytopenia appeared in parallel with liver dysfunction. She was diagnosed as having AITP by clinical and laboratory findings. Her serum showed a speckled pattern in immunofluorescence antinuclear antibody testing, but the antigen specificities were distinct from those of the known myositis-related autoantigens. This is a first case report of PM accompanied by AIH, PBC, and AITP. It was notable that there was an overlap of disease-associated immunological findings and immunogenetic backgrounds. This case provides a possible insight into the mechanisms and interplay of autoimmune diseases.

Differential immunohistological features of inflammatory myopathies and dysferlinopathy

This study was performed in order to characterize the types of the infiltrating cells, and the expression profiles of major histocompatibility complex (MHC) class I and membrane attack complex (MAC) in patients with inflammatory myopathies and dysferlinopathy. Immunohistochemical stains were performed using monoclonal antibodies against several inflammatory cell types, MHC class I, and MAC in muscles from inflammatory myopathies and dysferlinopathy. There was significant difference in the types of infiltrating cells between polymyositis (PM), dermatomyositis (DM), and dysferlinopathy, including significantly high CD4+/CD8+ T cell ratio and B/T cell ratio in DM. In dysferlinopathy, CD4+ T cells were the most abundant and the proportions of infiltrating cell types were similar to those of DM. MHC class I was expressed in muscle fibers of PM and DM regardless of the presence of inflammatory infiltrates. MAC was expressed in necrotic fibers and vessels of PM and DM. One patient with early stage DM had a MAC deposits on endomysial capillaries. In dysferlinopathy, MAC deposit was also observed on the sarcolemma of nonnecrotic fibers. The analysis of inflammatory cells, MHC class I expressions and MAC deposits may help to differentiate dysferlinopathy from idiopathic inflammatory myopathy.

Anti-Mi-2 antibodies

Autoantibodies targeting the Mi-2 nuclear antigen represent one of the serologic hallmarks of idiopathic inflammatory myopathies, with a diagnostic sensitivity and specificity of approximately 4-18% and 98-100%, respectively. Mi-2 antigen is a component of the nuclesome remodeling-deacetylase (NuRD) complex involved in transcription regulation.Anti-Mi-2 antibodies are strongly associated with dermatomyositis (frequency up to 31%) and have a very high positive predictive value for such disease subset. A strong correlation with HLA-DR7 has been demonstrated. At the moment, optimal serologic testing is achieved by ELISA screening on recombinant Mi-2 antigen and confirmation of positive results on immunoblot.

Anti-Jo-1 Antibodies

Anti-Jo-1 antibody is a myositis specific autoantibody most commonly found in patients with idiopathic inflammatory myopathies (IIM). This antibody is directed against the histidyl-tRNA synthetase which catalyses the binding of the histidine to its cognate tRNA during protein synthesis. It can be considered a specific marker of IIM, predominantly found in 20-30% of patients with PM and in the 60-70% of those with interstitial pulmonary fibrosis. These antibodies are also found in DM, although less frequently than in PM, and are rare in children with PM or DM and in other connective tissue diseases.ELISA, CIE and immunoblotting are highly specific and sensitive techniques for testing anti-Jo-1 antibodies. The detection of this antibody is particularly useful in diagnosis and classification of IIM. Moreover, anti-Jo-1 serum levels strongly correlate with disease activity representing a good marker for disease monitoring.

Update on idiopathic inflammatory myopathies

The inflammatory myopathies are a group of acquired diseases, characterized by an inflammatory infiltrate of the skeletal muscle. On the basis of clinical, immuno-pathological and demographic features, three major diseases can be identified: dermatomyositis (DM); polymyositis (PM); and inclusion body myositis (IBM). New diagnostic criteria have recently been introduced, which are crucial for discriminating between the three different subsets of inflammatory myopathies and for excluding other disorders. DM is a complement-mediated microangiopathy affecting skin and muscle. PM and IBM are T cell-mediated disorders, where CD8-positive cytotoxic T cells invade muscle fibres expressing MHC class I antigens, thus leading to fibre necrosis. In IBM, vacuolar formation with amyloid deposits are also present. This article summarizes the main clinical, laboratory, electrophysiological, immunological and histologic features as well as the therapeutic options of the inflammatory myopathies.

Polymyositis/dermatomyositis and interstitial lung disease: A new therapeutic approach with T-cell-specific immunosuppressants

Interstitial lung disease (ILD) is a common complication of polymyositis (PM) and dermatomyositis (DM), and accounts for a significant proportion of their morbidity and mortality because of the resistance to therapeutic agents including corticosteroids. Its pathogenic mechanism is not known, but several studies have provided findings implicating that T-cells, especially activated CD8+ cells, may play essential roles, and thus could be therapeutic targets in this disease. To test this hypothesis, we began clinical investigation of the efficacy of T-cell-specific immunosuppressants, cyclosporine (CsA) and FK506, in PM/DM patients with ILD. In our retrospective nationwide multi-center study compiling a total of 53 patients, a combination of CsA and corticosteroids resulted in favorable early and long-term outcome in the majority of patients except for DM patients with acute ILD. In this subset, those who received the combination as an initial therapy had better survival than those who initially received corticosteroids alone. FK506 has a similar mode of action but is up to 100-fold more potent than CsA in vitro, and has been used in more refractory ILD cases. We next reviewed 5 PM/DM patients with ILD who failed on various immunosuppressants including CsA and were subsequently treated with FK506 in our hospital, and found that 3 improved promptly, 1 gradually and steadily, and another case responded slowly after prednisolone dose was increased. None developed adverse effects. In summary, these T-cell targeted therapies have a potential to be the cornerstone of the treatment for ILD in PM/DM patients. The combination therapy with CsA and corticosteroids may be efficacious especially when used early. FK506 may be advantageous even in refractory cases to CsA. These findings indicate that further investigation is warranted. Currently, prospective investigation of FK506 is underway.