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Background: Identification of mononuclear cellular infiltrates in skeletal muscle tissue is the histological cornerstone of the diagnosis of idiopathic inflammatory myopathy (IIM). However, these infiltrates are not always present.

Objective: To determine whether MHC class I antigen expression on the sarcolemma, which is absent in normal muscle tissue, is upregulated in IIM and could serve as an additional diagnostic test.

Methods: Expression of MHC class I antigens was studied in 224 muscle samples of 61 adult patients with IIM (9 dermatomyositis, 23 polymyositis, 29 inclusion body myositis) and 163 controls (normal subjects and patients with various neuromuscular disorders) in a prospective blinded manner.

Results: The sensitivity of the test for diagnosing IIM was 78% (95% confidence interval (CI), 66% to 88%), with a specificity of 95% (91% to 98%). The sensitivity before the start of immunosuppressive treatment was 89% (76% to 96%). The sensitivity was not changed by including all patients who had been on immunosuppressive treatment for less than four weeks before muscle biopsy (sensitivity 90% (79% to 97%)). False positive results were found in only seven controls (4%), six of whom had a muscular dystrophy.

Conclusions: Detection of sarcolemmal MHC class I is a valid test for IIM. It is not affected by the short term use of immunosuppressive agents (less than four weeks) and it should be incorporated in the histological evaluation when the diagnosis of IIM is under consideration or needs to be excluded.

Background

Idiopathic inflammatory myopathies (IIMs) are a rare group of autoimmune syndromes characterized by chronic muscle inflammation and muscle weakness with no known cause. Little is known about their incidence and prevalence. This study reports the incidence and prevalence of IIMs among commercially insured and Medicare and Medicaid enrolled populations in the US.

Methods

We retrospectively examined medical claims with an IIM diagnosis (ICD-9-CM 710.3 [dermatomyositis (DM)], 710.4 [polymyositis (PM)], 728.81[interstitial myositis]) in the MarketScan® databases to identify age- and gender-adjusted annual IIM incidence and prevalence for 2004–2008. Sensitivity analysis was performed for evidence of a specialist visit (rheumatologist/ neurologist/dermatologist), systemic corticosteroid or immunosuppressant use, or muscle biopsy.

Results

We identified 2,990 incident patients between 2004 and 2008 (67% female, 17% Medicaid enrollees, 27% aged ≥65 years). Overall adjusted IIM incidence for 2004–2008 for commercial and Medicare supplemental groups combined were 4.27 cases (95% CI, 4.09-4.44) and for Medicaid, 5.23 (95% CI 4.74-5.72) per 100,000 person-years (py). Disease sub-type incidence rates per 100,000-py were 1.52 (95% CI 1.42-1.63) and 1.70 (1.42-1.97) for DM, 2.46 (2.33-2.59) and 3.53 (3.13-3.94) for PM, and 0.73 (0.66-0.81) and 0.78 (0.58-0.97) for interstitial myositis for the commercial/Medicare and Medicaid cohorts respectively. Annual incidence fluctuated over time with the base MarketScan populations. There were 7,155 prevalent patients, with annual prevalence ranging from 20.62 to 25.32 per 100,000 for commercial/Medicare (83% of prevalent cases) and from 15.35 to 32.74 for Medicaid.

Conclusions

We found higher IIM incidence than historically reported. Employer turnover, miscoding and misdiagnosing, care seeking behavior, and fluctuations in database membership over time can influence the results. Further studies are needed to confirm the incidence and prevalence of IIM.

Muscle inflammation and weakness are the key features of idiopathic inflammatory myopathies (IIMs). In addition IIMs are frequently associated with cutaneous and pulmonary involvement. In clinical practice the three common inflammatory myopathies we come across are polymyositis (PM), dermatomyositis (DM) and inclusion body myositis (IBM). The Bohan and Peter criteria combine clinical, laboratory, and pathologic features to define PM and DM. They did not recognize inclusion body myositis (IBM) or other inflammatory myopathies, such as granulomatous and eosinophilic myositis. Thus the disease spectrum is wide and IIMs are a heterogeneous group of autoimmune disorders. To address these issues in this article we have discussed the currently developing newer classifications of IIMs.

Introduction

Idiopathic inflammatory myopathies (IIM or myositis), is a group of autoimmune diseases that result in decreased muscle strength and/or endurance. Non-invasive tools to assess muscle may improve our understanding of the clinical and functional consequences of myopathies and their response to treatment. This study examined Magnetic Resonance Elastography (MRE), a non-invasive technique that assesses the shear modulus (stiffness) of muscle, in IIM subjects.

Methods

Nine subjects with active myositis completed the MRE protocol. Participants lay in a positioning device, and scans of the vastus medialis (VM) were taken in the relaxed state and at two contraction levels. Manual inversion was used to estimate the stiffness.

Results

A significant reduction in muscle stiffness was seen in myositis subjects compared with healthy controls during the ‘relaxed’ condition.

Discussion

The use of non-invasive technologies such as MRE may provide greater understanding of the pathophysiology of IIM and improve assessment of treatment efficacy.

Objective. Serum cytokines play an important role in the pathogenesis of myositis by initiating and perpetuating various cellular and humoral autoimmune processes. The aim of the present study was to describe a broad spectrum of T- and B-cell cytokines, growth factors and chemokines in patients with idiopathic inflammatory myopathies (IIMs) and healthy individuals.

Methods. A protein array system, denoted as multiplex cytokine assay was utilized to measure simultaneously the levels of 24 circulating cytokines, including B-cell activating factor (BAFF) and a proliferation inducing ligand (APRIL) of patients with IIMs and healthy individuals. Additionally, correlational clustering and discriminant function analysis (DFA), two multivariate, supervised analysis methods were employed to identify a subset of biomarkers in order to describe potential functional interrelationships among these pathological cytokines.

Results. Univariate analysis demonstrated that a complex set of immune and inflammatory modulating cytokines are significantly up-regulated in patients with IIMs relative to unaffected controls including IL-10, IL-13, IFN-α, epidermal growth factor (EGF), VEGF, fibroblast growth factor (FGF), CCL3 [macrophage inflammatory protein (MIP-1α)], CCL4 (MIP-1β) and CCL11 (eotaxin), whereas G-CSF was significantly reduced in IIM patients. Correlational clustering was able to discriminate between, and hence sub-classify patients with IIMs. DFA identified EGF, IFN-α, VEGF, CCL3 (MIP-1α) and IL-12p40, as analytes with the strongest discriminatory power among various myositis patients and controls.

Conclusions. Our findings suggest that these factors modulate myositis pathology and help to identify differences between subsets of the disease.

The lung is one of the most common extra-muscular targets in idiopathic inflammatory myopathies (IIM) and interstitial lung disease (ILD) is a prevalent and often devastating manifestation of IIM. IIM-associated ILD (IIM-ILD) contributes to nearly 80% of the mortality in IIM with a reported prevalence of 65% of newly diagnosed IIM cases. Although ILD frequently accompanies clinical and laboratory findings of myositis, overt signs of muscle disease may be absent in the setting of significant lung disease. Understanding the varied scope of presentation of these diseases is essential to providing optimal patient care. This review will provide an in depth examination of ILD in IIM both from a rheumatologic and pulmonary perspective and will discuss the scope of disease, presenting features, genetic associations, pathogenesis, diagnosis, radiographic and histopathologic findings, along with biomarker assessment and a rationale for therapeutic intervention.

Idiopathic inflammatory myopathies (IIMs), comprising of polymyositis, dermatomyositis, and inclusion-body myositis, are characterized by muscle weakness and various types of inflammatory changes in muscle cells. They also show non-inflammatory changes, including perifascicular atrophy, mitochondrial changes, and amyloid protein accumulation. It is possible that some molecules/mechanisms bridge the extracellular inflammatory stimulation and intracellular non-inflammatory changes. One such mechanism, Ca2+ influx leading to calpain activation has been proposed. In this study, we demonstrated that post-treatment with calpeptin (calpain inhibitor) attenuated intracellular changes to prevent apoptosis (Wright staining) through both mitochondrial pathway (increase in Bax:Bcl-2 ratio) and endoplasmic reticulum stress pathway (activation of caspase-12), which were induced by interferon-gamma (IFN-γ) stimulation in rat L6 myoblast cells. Our results also showed that calpeptin treatment inhibited the expression of calpain, aspartyl protease cathepsin D, and amyloid precursor protein. Thus, our results indicate that calpain inhibition plays a pivotal role in attenuating muscle cell damage from inflammatory stimulation due to IFN-γ, and this may suggest calpain as a possible therapeutic target in IIMs.

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

Objective

We assessed birth patterns of patients with idiopathic inflammatory myopathies (IIM), hypothesizing that seasonal early environmental exposures influence later development of autoimmune disease.

Methods

Juvenile-onset patients (n = 307) and healthy controls (n = 3,942) were born from 1970−1999, and adult-onset patients (n = 668) and controls (n = 6,991) from 1903−1982. Birth dates were analyzed as circular data. Seasonal clustering was assessed by the Rayleigh test, and differences between groups by a rank-based Uniform-Scores Test.

Results

The overall birth distributions of juvenile IIM patients and controls did not significantly differ nor did those of adult IIM patients vs. controls. Subgroups of juvenile IIM showed seasonal birth distributions: Hispanic juvenile IIM patients had a seasonal birth pattern (mean October 16), differing (p = 0.002) from those of Hispanic controls (uniform birth distribution) and from non-Hispanic juvenile patients (mean May 2, p < 0.001). Juvenile dermatomyositis patients with p155 autoantibody differed in birth distribution (p = 0.003) from p155 antibody-negative juvenile dermatomyositis patients. Juvenile IIM patients with the human leukocyte antigen (HLA) risk factor allele DRB1*0301 differed in birth distribution (p = 0.021) from those without the allele. Similar results were observed for juvenile and adult IIM patients with the linked allele DQA1*0501. No significant seasonal birth patterns were found for other subgroups.

Conclusion

Birth distributions appear to have stronger seasonality in juvenile than adult IIM subgroups, suggesting greater influence of perinatal exposures on childhood-onset illness. Seasonal early-life exposures may influence the onset of some autoimmune diseases later in life.

This review summarizes the previous and current literature on the immunogenetics of idiopathic inflammatory myopathy (IIM) and updates the research progress that has been made over the past decade. A substantial part of the genetic risk for developing adult- and juvenile-onset IIM lies within the major histocompatibility complex (MHC), and a tight relationship exists between individual human leukocyte antigen alleles and specific serological subtypes, which in turn dictate clinical disease phenotypes. Multiple genetic regions outside of the MHC are increasingly being identified in conferring IIM disease susceptibility. We are still challenged with the task of studying a serologically and clinically heterogeneous disorder that is rarer by orders of magnitude than the likes of rheumatoid arthritis. An ongoing and internationally coordinated IIM genome-wide association study may provide further insights into IIM immunogenetics.

Objectives

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

Methods

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

Results

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

Conclusion

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

Macrophages play a critical role in both innate and acquired immunity because of their unique ability to internalize, kill, and degrade bacterial pathogens through the process of phagocytosis. The adaptor protein, amphiphysin IIm, participates in phagocytosis and is transiently associated with early phagosomes. Certain pathogens, including Chlamydia pneumoniae, have evolved mechanisms to subvert macrophage phagosome maturation and, thus, are able to survive within these cells. We report here that, although amphiphysin IIm is usually only transiently associated with the phagosome, it is indefinitely retained on vacuoles containing C. pneumoniae. Under these wild-type conditions, C. pneumoniae do not elicit significant nitric oxide (NO) production and are not killed. Abrogation of amphiphysin IIm function results in C. pneumoniae–induced NO production and in the sterilization of the vacuole. The data suggest that C. pneumoniae retains amphiphysin IIm on the vacuole to survive within the macrophage.

Objectives. The paediatric idiopathic inflammatory myopathies (IIMs) are a group of rare chronic inflammatory disorders of childhood, affecting muscle, skin and other organs. There is a severe lack of evidence base for current treatment protocols in juvenile myositis. The rarity of these conditions means that multicentre collaboration is vital to facilitate studies of pathogenesis, treatment and disease outcomes. We have established a national registry and repository for childhood IIM, which aims to improve knowledge, facilitate research and clinical trials, and ultimately to improve outcomes for these patients.

Methods. A UK-wide network of centres and research group was established to contribute to the study. Standardized patient assessment, data collection forms and sample protocols were agreed. The Biobank includes collection of peripheral blood mononuclear cells, serum, genomic DNA and biopsy material. An independent steering committee was established to oversee the use of data/samples. Centre training was provided for patient assessment, data collection and entry.

Results. Ten years after inception, the study has recruited 285 children, of which 258 have JDM or juvenile PM; 86% of the cases have contributed the biological samples. Serial sampling linked directly to the clinical database makes this a highly valuable resource. The study has been a platform for 20 sub-studies and attracted considerable funding support. Assessment of children with myositis in contributing centres has changed through participation in this study.

Conclusions. This establishment of a multicentre registry and Biobank has facilitated research and contributed to progress in the management of a complex group of rare muscloskeletal conditions.

In idiopathic inflammatory myopathies (IIMs), extracellular inflammatory stimulation is considered to induce secondary intracellular inflammatory changes including expression of major histocompatibility complex class-I (MHC-I) and to produce self-sustaining loop of inflammation. We hypothesize that activation of calpain, a Ca2+-sensitive protease, bridges between these extracellular inflammatory stress and intracellular secondary inflammatory changes in muscle cells. In this study, we demonstrated that treatment of rat L6 myoblast cells with interferon-gamma (IFN-γ) caused expression of MHC-I and inflammation related transcription factors (phosphorylated-extracellular signal-regulated kinase 1/2 and nuclear factor-kappa B). We also demonstrated that treatment with tumor necrosis factor-alpha (TNF-α) induced apoptotic changes and activation of calpain and cyclooxygenase-2. Further, we found that post-treatment with calpeptin attenuated the intracellular changes induced by IFN-γ or TNF-α. Our results indicate that calpain inhibition attenuates apoptosis and secondary inflammatory changes induced by extracellular inflammatory stimulation in the muscle cells. These results suggest calpain as a potential therapeutic target for treatment of IIMs.

Objectives

Clinical care and therapeutic trials in idiopathic inflammatory myopathies (IIM) require accurate and consistent assessment of cutaneous involvement. The Cutaneous Assessment Tool (CAT) was designed to measure skin activity and damage in IIM. We describe the development and inter-rater reliability of the CAT, and the frequency of lesions endorsed in a large population of juvenile IIM patients.

Methods

The CAT includes 10 activity, 4 damage and 7 combined lesions. Thirty-two photographic slides depicting IIM skin lesions were assessed by 11 raters. One hundred and twenty three children were assessed by 11 pediatric rheumatologists at ten centers. Inter-rater reliability was assessed using simple agreements and intra-class correlation coefficients (ICC).

Results

Simple agreements in recognizing lesions as present or absent were generally high (0.5 – 1.0). ICC's for CAT lesions were moderate (0.4 – 0.75) in both slides and real patients. ICC's for the CAT activity and damage scores were 0.71 and 0.81, respectively. CAT activity scores ranged from 0 – 44 (median 7, potential range 0 – 96) and CAT damage scores ranged from 0 – 13 (median 1, potential range 0 – 22). The most common cutaneous lesions endorsed were periungual capillary loop changes (63%), Gottron's papules/sign (53%), heliotrope rash (49%) and malar/facial erythema (49%).

Conclusions

Total CAT activity and damage scores have moderate to good reliability. Assessors generally agree on the presence of a variety of cutaneous lesions. The CAT is a promising, semi-quantitative tool to comprehensively assess skin disease activity and damage in IIM.

The idiopathic inflammatory myopathies (IIMs) are rare disorders with the unifying feature of proximal muscle weakness. These diseases include polymyositis(PM), dermatomyositis (DM) and inclusion body myositis (IBM) as the most common. The diagnosis is based on the finding of weakness on exam, elevated muscles enzymes, characteristic histopathology of muscle biopsies, electromyography abnormalities and rash in DM. Myositis-specific antibodies have been helpful in defining subsets of patients with different responses to treatment and prognosis. The cornerstone of therapy is corticosteroids with the addition of other immunosuppressives in severe or refractory disease or patients with intolerable side effects. IBM is particularly difficult to treat but is more slowly progressive as compared with PM or DM. There is still a great need to find more effective and less-toxic therapies.

Background

Little is known about the clinical features and true survival risk factors in Chinese Han population. We conducted the current study to investigate the clinical features, long-term outcome and true potential indicators associated with mortality of idiopathic inflammatory myopathies (IIM) in China.

Methods

We restrospectvely investigated 188 patients diagnosed with IIM at our hospital from January 1986 to April 2009. The primary outcome was determined with mortality. The secondary outcomes for survival patients were organ damage and disease activity, health status, and disability, which were assessed with Myositis Damage Index, Myositis Disease Activity Assessment Visual Analogue Scales, Health Assessment Questionnaire Disability Index, and the Modified Rankin Scale, respectively. Potential prognostic factors for mortality were analyzed with the multivariate Cox regression model.

Results

Mean age at disease onset was 43.8 ± 15.8 years and male to female ratio was 1:2.1 in this cohort. The 1-, 5-, 10-, 15- and 20-year survival rates were 93.6%, 88.7%, 81%, 73.6% and 65.6%. The independent predicators for mortality were age at disease onset [hazard ratio (HR):1.05, 95% CI 1.02 - 1.08], presence of cancer (HR:3.68, 95%CI 1.39 - 9.74), and elevated IgA level at diagnosis (HR:2.80, 95% CI 1.16-6.74). At the end of the follow-up, 29 patients manifested drug withdrawal within an average 4.1 years (range 0.5-15.2 year), most patients (85.9%) had no disease activity and 130 patients (83.4%) had no disability.

Conclusions

The long-term outcomes of IIM patients in our cohort have improved dramatically. Those patients most likely to survive had a high chance of reaching stable disease status, and obtained long-term or possibly permanent remission to a large extent.

Introduction

The objective of this study is to determine if multiple systemic autoimmune diseases (SAID) share gene expression pathways that could provide insights into pathogenic mechanisms common to these disorders.

Methods

RNA microarray analyses (Agilent Human 1A(V2) 20K oligo arrays) were used to quantify gene expression in peripheral blood cells from 20 monozygotic (MZ) twin pairs discordant for SAID. Six affected probands with systemic lupus erythematosus (SLE), six with rheumatoid arthritis (RA), eight with idiopathic inflammatory myopathies (IIM), and their same-gendered unaffected twins, were enrolled. Comparisons were made between discordant twin pairs and these were also each compared to 40 unrelated control subjects (matched 2:1 to each twin by age, gender and ethnicity) using statistical and molecular pathway analyses. Relative quantitative PCR was used to verify independently measures of differential gene expression assessed by microarray analysis.

Results

Probands and unrelated, matched controls differed significantly in gene expression for 104 probes corresponding to 92 identifiable genes (multiple-comparison adjusted P values < 0.1). Differentially expressed genes involved several overlapping pathways including immune responses (16%), signaling pathways (24%), transcription/translation regulators (26%), and metabolic functions (15%). Interferon (IFN)-response genes (IFI27, OASF, PLSCR1, EIF2AK2, TNFAIP6, and TNFSF10) were up-regulated in probands compared to unrelated controls. Many of the abnormally expressed genes played regulatory roles in multiple cellular pathways. We did not detect any probes expressed differentially in comparisons among the three SAID phenotypes. Similarly, we found no significant differences in gene expression when comparing probands to unaffected twins or unaffected twins to unrelated controls. Gene expression levels for unaffected twins appeared intermediate between that of probands and unrelated controls for 6535 probes (32% of the total probes) as would be expected by chance. By contrast, in unaffected twins intermediate ordering was observed for 84 of the 104 probes (81%) whose expression differed significantly between probands and unrelated controls.

Conclusions

Alterations in expression of a limited number of genes may influence the dysregulation of numerous, integrated immune response, cell signaling and regulatory pathways that are common to a number of SAID. Gene expression profiles in peripheral blood suggest that for genes in these critical pathways, unaffected twins may be in a transitional or intermediate state of immune dysregulation between twins with SAID and unrelated controls, perhaps predisposing them to the development of SAID given the necessary and sufficient environmental exposures.

Purpose of review

Recent literature in inflammatory myopathies suggests that both immune (cell-mediated and humoral) and non-immune (endoplasmic reticulum (ER) stress and autophagy) mechanisms play a role in muscle fiber damage and dysfunction. This review describes these findings and discusses their relevance to disease pathogenesis and therapy.

Recent findings

Recent data highlights the role of ER stress response especially the roles of Hexose-6-phosphate dehydrogenase and ER-anchored RING finger E3 ligase in the activation of unfolded protein response and the formation of vacuoles and inclusions in myopathies. Several studies investigated the link between inflammation and the beta amyloid associated muscle fiber degeneration and loss of muscle function. Likewise, the roles of ER stress and autophagy in skeletal muscle damage have been explored in multiple muscle diseases.

Summary

Current data indicate that the ER stress, NF-kB pathway and autophagy are active in the skeletal muscle of myositis patients, and the pro-inflammatory NF-kB pathway connects the immune and non-immune pathways of muscle damage. The relative contributions of each of these pathways to muscle fiber damage are presently unclear. Therefore further defining the role of these pathways in disease pathogenesis should help to design effective therapeutic agents for these diseases.

Objectives:

To study the electroclinical and histopathologic profile of idiopathic inflammatory myositis (IIM) with reference to prognosis and survival rate.

Materials and Methods:

Diagnosis of IIM was based on the Bohan and Peter criteria. Patients who improved and those whose condition worsened or who expired due to IIM per se at last follow-up were classified to have favorable and poor outcomes, respectively. Fisher’s exact test was used for univariate analysis of prognostic factors.

Results:

The study cohort consisted of consecutive 68 patients with IIM. The mean age at diagnosis was 36.5 years and females constituted 71%. Of these patients, 62% had definite IIM, 49% had polymyositis, 20% had dermatomyositis, and 29% had overlap syndrome. The mean follow-up period was 5.4 years. Prednisolone alone was used in 55 (80%), and azathioprine (1–3 mg/kg/day) alone in 12 (17.6%) as the initial treatment. Relapse of IIM with drug withdrawal was seen in 15 patients (22%); 70% had favorable outcome and 16% had expired. The treatment delay of ≤6 months (P = 0.001), absence of cardiac or lung involvement (P < 0.001), and positive biopsy (P = 0.033) were predictive of a favorable prognosis in the univariate analysis. In multivariate analysis, only the duration of illness of ≤6 months (P = 0.008) and the absence of cardiac or lung involvement (P = 0.001) predicted the favorable outcome at last follow-up. Cumulative survival rate was 95% at 1 year, 86% at the 5th year, and 80% at the 10th year.

Conclusions:

Approximately, two-thirds of the patients showed good electroclinical and histopathologic correlations and an equal number improved with treatment. The treatment delay (≥6 months), presence of cardiac or pulmonary involvements, and negative muscle biopsy are bad prognostic factors.

Sera from 19 patients with idiopathic inflammatory myopathy (IIM) were examined for the presence of anti-endothelial cell antibodies (AECA) by an immunoglobulin G-specific cellular enzyme-linked immunosorbent assay. The mean binding index of AECA was found to be 37.7% +/- 26.5% for the patients, compared with a mean of 7.2% +/- 2.7% for normal controls (P < 0.04). Levels of thrombomodulin, von Willebrand factor antigen, and serum creatine kinase were also shown to be augmented. Interestingly, positive correlations between AECA on the one hand and Raynaud's phenomenon and interstitial lung disease on the other were demonstrated. Given that the pathogenesis of IIM remains uncertain, these findings may be of importance.

Objective

To investigate possible associations of GM and KM markers in European Americans (EA) and African Americans (AA) with adult and juvenile forms of the idiopathic inflammatory myopathies (IIM).

Methods

We performed serologic analyses of polymorphic determinants associated with immunoglobulin gamma heavy (GM) and kappa light chains (KM) in large populations of EA (n=514: 297 adults and 217 juveniles) and AA IIM patients (n=109: 73 adults and 50 juveniles) representing the major clinicopathologic and autoantibody groups.

Results

For EA dermatomyositis (DM) patients, the GM 3 23 5,13 phenotype was a risk factor for both adults (OR=2.2; Pc=0.020) and juveniles (OR=2.2; Pc=0.0013). Of interest, the GM 13 allotype was a risk factor for juvenile DM (JDM) for both EA (OR=3.9; Pc<0.0001) and AA (OR=4.8; Pc=0.033). However, the GM 1,3,17 5,13,21 phenotype was a risk factor for JDM in EA but not in AA. Among the IIM autoantibody groups, GM 3 23 5,13 was a risk factor for EA adults with anti-Jo-1 autoantibodies (OR=3.4; Pc=0.0031), while the GM 3 allotype was protective for adults with anti-threonyl tRNA synthetase or anti-RNP autoantibodies (OR=0.1; Pc=0.047 and OR=0.2; Pc=0.034, respectively). In contrast, GM 6 was a risk factor for AA adults with anti-SRP autoantibodies (OR=7.5; Pc=0.041).

Conclusions

These data suggest that polymorphic alleles of GM and KM loci are differentially associated with IIM subgroups defined by age, ethnicity, clinical features and autoantibodies, and expand the list of immune response genes possibly important in the pathogenesis of myositis.

The laboratory plays an important role in the diagnosis, evaluation, and classification of the heterogeneous group of diseases known as the IIM, which are characterized by chronic muscle inflammation. Serial measurements of the levels of muscle-derived enzymes in serum are the traditional laboratory studies used to follow the clinical course of patients with IIM, although other laboratory tests can also be useful in assessing myositis disease activity. Several markers of immune system activation, including cytokines and lymphocyte markers, show promise as possibly more sensitive measures of myositis disease activity. Discovery of a unique group of MSAs over the past decade has provided an immunologic basis for defining relatively homogeneous subsets of patients who share similar clinical features, disease courses, and responses to therapy. Future investigations of novel immunologic activation markers, as well as the cloning and expression of target autoantigens of the MSAs, should allow better diagnostic assays, enhanced prognosis, and a better understanding of the pathogenesis of these disorders.

The largest subunit of the mammalian RNA polymerase II possesses a C-terminal domain (CTD) consisting of 52 repeats of the consensus sequence, Tyr(1)-Ser(2)-Pro(3)-Thr(4)-Ser(5)-Pro(6)-Ser(7). Phosphorylation of the CTD is known to play a key role in gene expression. We now show that treatments such as osmotic and oxidative shocks or serum stimulation generate a new type of phosphorylated subunit, the IIm form. This IIm form might be generated in vivo by ERK-type MAP kinase phosphorylation as: (i) ERK1/2 are major CTD kinases found in cell extracts; (ii) the immunoreactivity of the IIm form against a panel of monoclonal antibodies indicates that the CTD is exclusively phosphorylated on Ser-5 in the repeats, like RNA polymerase II phosphorylated in vitro by an ERK1/2; and (iii) the IIm form does not appear when ERK activation is prevented by treating cells with low concentrations of highly specific inhibitors of MEK1/2. Since the IIm subunit is not affected by inhibition of transcription and is not bound to chromatin, it does not participate in transcription.

Introduction

The endoplasmic reticulum (ER) stress-response, evoked in mice by the overexpression of class I major histocompatibility complex antigen (MHC-I), was proposed as a major mechanism responsible for skeletal muscle damage and dysfunction in autoimmune myositis. The present study was undertaken to characterize in more detail the ER stress-response occurring in myofibers of patients with inflammatory myopathies, focusing on the expression and distribution of Grp94, calreticulin and Grp75, three ER chaperones involved in immunomodulation.

Methods

Muscle biopsies were obtained from seven healthy subjects and 29 myositis patients, who were subdivided into groups based on the morphological evidence of inflammation and/or sarcolemmal immunoreactivity for MHC-I. Biopsies were analyzed by means of immunohistochemistry and western blot using anti-Grp94, anti-calreticulin and anti-Grp75 specific antibodies. Parallel analyses on these ER chaperones were conducted in rabbit and/or murine skeletal muscle after experimental induction of regeneration or systemic inflammation.

Results

Upregulation of Grp94 characterized regenerating myofibers of myositis patients (P = 0.03, compared with values detected in biopsies without signs of muscle regeneration) and developing and regenerating myofibers of mouse muscles. Conversely, levels of calreticulin and Grp75 increased about fourfold and twofold, respectively, in patient biopsies positive for sarcolemmal MHC-I immunoreactivity, compared with healthy subjects and patients negative for both inflammation and MHC-I labeling (P < 0.005). Differently from calreticulin, the Grp75 level increased significantly also in patient biopsies that displayed occasional sarcolemmal MHC-I immunoreactivity (P = 0.002), suggesting the interference of other mechanisms. Experimental systemic inflammation achieved in mice and rabbits by a single injection of bacterial lipopolysaccharide significantly increased Grp75 and calreticulin but not MHC-I expression in muscles.

Conclusions

These results indicate that, in myositis patients, muscle regeneration and inflammation, in addition to MHC-I upregulation, do evoke an ER stress-response characterized by the increased expression of Grp94 and Grp75, respectively. The increase in the muscle Grp75 level in patients showing occasional immunoreactivity for sarcolemmal MHC-I might be considered further as a broader indicator of idiopathic inflammatory myopathy.