Dermatomyositis and polymyositis: Clinical presentation, autoantibodies, and pathogenesis

Comparative analysis of immunotherapy responses in small cell lung cancer patients with dermatomyositis

Cancer-associated dermatomyositis (CAD), a paraneoplastic syndrome characterized by dermatomyositis (DM), frequently presents in association with small cell lung cancer (SCLC). Although the advent of immune checkpoint inhibitors (ICIs) has revolutionized cancer treatment, their efficacy and safety in patients with concurrent autoimmune diseases (AD) and malignancies remains uncertain. Several studies have suggested the safe administration of ICIs in patients with AD, indicating that successful cancer therapy can alleviate CAD symptoms. Conversely, other studies have raised concerns about the potential for ICIs to exacerbate AD flares or immune-related adverse events (irAEs). A comparative analysis of two cases from our institution emphasizes the variability in ICI responses among SCLC patients with CAD. One patient, previously reported as a case study, exhibited significant clinical improvement in DM symptoms after ICI administration, whereas the other developed severe exfoliative skin changes and experienced an unfavorable prognosis. This variability emphasizes the need for careful patient selection and close monitoring during ICI treatment. We hypothesized that overweight or obese individuals and those with severe initial skin lesions and elevated lactate dehydrogenase levels are more susceptible to developing irAEs following ICI therapy. Therefore, caution is advised when considering immunotherapy in these patients.

Patients with dermatomyositis shared partially similar transcriptome signature with COVID-19 infection

Dermatomyositis (DM) is an autoimmune disease that primarily affects the skin and skeletal muscle. Virus infection and type I interferon-related signaling pathways play an important role in the pathogenesis of dermatomyositis. In this study, we found that the skin of patients with DM and the skin of patients with COVID-19 have similar transcriptional profiles, and identified key genes involved in dermatomyositis based on bioinformatics analysis. These hub-genes might be served as potential biomarkers for the early diagnosis and therapy of DM, including MX1, ISG15, IFIT3, IFIT1, RSAD2, IFIT2, IFI6, XAF1, IRF9, MX2.

Structure, demography, and medico-social characteristics of articular syndrome in rheumatic diseases: a retrospective monocentric analysis of 2019-2021 data

Rheumatic diseases encompass a wide range of conditions characterised by joint inflammation and pain, significantly impacting individuals' quality of life. Articular syndrome, manifested through joint-related symptoms such as pain, swelling, and reduced mobility, is a common feature of rheumatic diseases. This study aimed to analyze articular syndrome's structure, demography, and medico-social characteristics in rheumatic diseases.  We retrieved case notes of 370 patients examined in 2019-2021 at the Rheumatology Department of the Regional Clinical Hospital, Shymkent, Kazakhstan. We processed data on gender, age, place of residence, social status, clinical diagnosis, comorbid conditions, complications, and delays. The material was counted by frequency analysis. Statistical and mathematical data processing was performed using the SPSS application software package version 26.0 (IBM).  The identified rheumatic diseases among the patients included rheumatoid arthritis (183), systemic lupus erythematosus (47), osteoarthritis (42), ankylosing spondylitis (31), systemic scleroderma (30), reactive arthritis (18), gouty arthritis (14), psoriatic arthritis (3), and dermatomyositis (2). The distribution of patients with articular syndrome varied across the study years, with 102 patients in 2019, 216 patients in 2020, and 52 patients in 2021. The study revealed the age distribution of patients, with an average age of 46 at the time of examination and an average age of disease onset at 39. The study further investigated the distribution of rheumatic diseases categorized by gender, place of residence (urban or rural), and disease duration. Additionally, the study examined the prevalence of comorbid conditions and complications related to the underlying rheumatic disease.  By examining the structure, demography, and medico-social characteristics of the articular syndrome in patients with rheumatic diseases, this retrospective analysis provides valuable insights into the epidemiological aspects of these conditions. The findings may contribute to a better understanding of the burden of rheumatic diseases on individuals and society. Such knowledge can aid in developing targeted interventions, improving healthcare delivery, and enhancing patients' overall well-being.

Clinical pearls and promising therapies in myositis

INTRODUCTION

Idiopathic inflammatory myopathies (IIMs) represent a diverse group of systemic autoimmune disorders with variable clinical manifestations and disease course. Currently, the challenges of IIMs are multifold, including difficulties in timely diagnosis owing to clinical heterogeneity, limited insights into disease pathogenesis, as well as a restricted number of available therapies. However, advances utilizing myositis-specific autoantibodies (MSAs) have facilitated the definition of subgroups as well as prediction of clinical phenotypes, disease course, and response to treatment.

AREAS COVERED

Herein we provide an overview of the clinical presentations of dermatomyositis (DM), anti-synthetase syndrome (ASyS), immune-mediated necrotizing myopathy (IMNM) and inclusion body myositis (IBM). We then provide an updated review of available and promising therapies for each of these disease groups. We synthesize current treatment recommendations in the context of case-based construct to facilitate application to patient care. Finally, we provide high-yield, clinical pearls relevant to each of the subgroups that can be incorporated into clinical reasoning.

EXPERT OPINION

There are many exciting developments on the horizon for IIM. As insights into pathogenesis evolves, the therapeutic armamentarium is expanding with many novel therapies in development, holding promise for more targeted treatment approaches.

Granzyme B in Autoimmune Skin Disease

Autoimmune diseases often present with cutaneous symptoms that contribute to dysfunction, disfigurement, and in many cases, reduced quality-of-life. Unfortunately, treatment options for many autoimmune skin diseases are limited. Local and systemic corticosteroids remain the current standard-of-care but are associated with significant adverse effects. Hence, there is an unmet need for novel therapies that block molecular drivers of disease in a local and/or targeted manner. Granzyme B (GzmB) is a serine protease with known cytotoxic activity and emerging extracellular functions, including the cleavage of cell-cell junctions, basement membranes, cell receptors, and other structural proteins. While minimal to absent in healthy skin, GzmB is markedly elevated in alopecia areata, interface dermatitis, pemphigoid disease, psoriasis, systemic sclerosis, and vitiligo. This review will discuss the role of GzmB in immunity, blistering, apoptosis, and barrier dysfunction in the context of autoimmune skin disease. GzmB plays a causal role in the development of pemphigoid disease and carries diagnostic and prognostic significance in cutaneous lupus erythematosus, vitiligo, and alopecia areata. Taken together, these data support GzmB as a promising therapeutic target for autoimmune skin diseases impacted by impaired barrier function, inflammation, and/or blistering.

NLRP3 inflammasome up-regulates major histocompatibility complex class I expression and promotes inflammatory infiltration in polymyositis

Objective

This study was designed to investigate the role of the nucleotide-binding-domain -and leucine-rich repeat -containing (NLR) family, pyrin-domain-containing 3 (NLRP3) inflammasome in the pathogenesis of polymyositis (PM).

Methods

Immunochemistry was performed to analyze the NLRP3, caspase-1 and interleukin-1 beta (IL-1β) expression in the muscle tissue of PM patients. Rat model of PM and C2C12 cell were used to investigate the potential role of NLRP3 inflammasome in PM.

Results

The percentage of CD 68+ macrophages, and the expression levels of NLRP3, caspase-1 and IL-1β in the muscle tissue were elevated in 27 PM patients. LPS/ATP treatment resulted in activation of NLRP3 inflammasome and secretion of IL-1β as well as interferons (IFNs) and monocyte chemotactic protein-1 (MCP-1) in the Raw 264.7 macrophages. Meanwhile, LPS/ATP challenged activation of NLRP3 inflammasome induced overexpression of major histocompatibility complex class I (MHC-I), a key molecular of PM in the co-cultured C2C12 cells. The effect was decreased by treatment of NLRP3 inflammasome inhibitor MCC950 or siRNA of NLRP3 inflammasome. These findings suggested certain levels of IL-1β rather than IFNs up-regulated MHC-I expression in C2C12 cells. IL-1β blockade using neutralizing IL-1β monoclonal antibody or siRNA of IL-1β suppressed MHC-I overexpression. In vivo, NLRP3 inflammasome inhibition by MCC950 reduced the expression of NLRP3, IL-1β and MHC-I in the muscle tissue of PM modal rats. Also, it attenuated the intensity of muscle inflammation as well as the CRP, CK, and LDH levels in the serum.

Conclusion

NLRP3/caspase-1/IL-1β axis may play an important role in the development of PM. Inhibition of NLRP3 activation may hold promise in the treatment of PM.

Long-Term Outcomes and Prognosis Factors in Patients With Idiopathic Inflammatory Myopathies Based on Myositis-Specific Autoantibodies: A Single Cohort Study

OBJECTIVE

This study was undertaken to investigate the long-term survival rates and prognostic factors in patients with idiopathic inflammatory myopathies (IIMs) based on myositis-specific antibody (MSA) stratification.

METHODS

Exactly 628 patients with an IIM were included. Kaplan-Meier survival curves, univariate, and multivariate Cox regression were used to analyze the outcomes and risk factors.

RESULTS

The cumulative 1-, 5-, and 10-year survival rates for IIM patients overall were 91.4%, 82.8%, and 75.6%, respectively. The survival rate in the MSA subset was significantly different (P < 0.001). The 1- and 10-year survival rates in the anti-melanoma differentiation-associated protein 5 (anti-MDA-5)-positive subgroup were 79.5% and 58.5%, respectively, which were the lowest among all subgroups. The 10-year survival rate of anti-signal recognition particle (anti-SRP)-positive patients was the highest (96.4%). Independent risk factors that impacted the long-term prognosis for IIM patients included rapidly progressive interstitial lung disease (RP-ILD), malignancy, and elevated serum ferritin levels (hazard ratio [HR] 17.47, 20.36, and 9.15, respectively, P < 0.01), whereas disease duration was a protective factor (HR 0.27, P = 0.003). Among these subsets, the strongest independent risk factor for death in the anti-MDA-5-positive subgroup was RP-ILD (HR 3.4, P = 0.017). Malignancy was an independent risk factor in the anti-aminoacyl-tRNA synthetase antibody-positive, anti-transcription intermediary factor 1γ-positive, and MSA-negative subgroups (HR 46.69, 6.65, and 4.48, respectively; P < 0.001). RP-ILD was also a risk factor in the prognosis of individuals in the MSA-negative subgroup (HR 72.28, P < 0.001).

CONCLUSION

Despite favorable overall survival in patients with IIM, the anti-MDA-5-positive subgroup had the highest mortality rate among all MSA subgroups, highlighting the distinctive prognosis for patients with different MSAs. RP-ILD and malignancy are the most common causes of death in IIM patients.

Incidence of systemic autoimmune myopathies and their risk of cancer in Leeds, UK: an 11-year epidemiological study

Objectives

The aims were to identify all incident adult cases of systemic autoimmune myopathies (SAMs) in the city of Leeds, UK, and to estimate the risk of cancer in SAMs as compared with the general population.

Methods

Cases of SAMs were ascertained by review of all muscle biopsy reports from the Neuropathology Laboratory. A review of medical records was undertaken for each case to review the clinical diagnosis and collect epidemiological data such as age, ethnicity, sex and comorbidities, including cancer. Leeds denominator population numbers were publicly obtainable.

Results

A total of 206 biopsy reports were identified and, after review, 50 incident cases were included in the study between June 2010 and January 2021. Of the 50 cases, 27 were male and 23 were female. The mean incidence rate of SAMs in Leeds throughout the study period was 7.42/1 000 000 person-years. The proportion of SAMs cases with a confirmed malignancy was 22%. Compared with the general population, the relative risk of cancer was significantly greater in the SAMs population (31.56; P < 0.01).

Conclusions

The incidence rate of SAMs in Leeds was consistent with data from previous literature; however, disagreement exists between different methods of SAMs case inclusion due to varying clinical criteria and definitions. SAMs are associated with an increased risk of cancer, but the pathogenesis of this relationship still requires investigating. This study supports the practice of malignancy screening and long-term surveillance in patients with SAMs.

A narrative review of interstitial lung disease in anti-synthetase syndrome: a clinical approach

Anti-synthetase syndrome (AS) is a rare autoimmune disorder characterized by the presence of aminoacyl-transfer RNA synthetase antibodies in conjunction with clinical features such as interstitial lung disease (ILD), Raynaud's phenomenon, nonerosive arthritis, and myopathy. AS distinguishes itself from other inflammatory myopathies by its significant lung involvement and rapidly progressive interstitial lung disease (AS-ILD), therefore the management of AS-ILD requires careful clinical, serologic and radiologic assessment. Glucocorticoids are considered the mainstay of therapy; however, additional immunosuppressive agents are often required to achieve disease control. Patient prognosis is highly dependent on early diagnosis and symptom recognition as the antibody profile is thought to influence therapy response. Since progressive ILD is the leading cause of morbidity and mortality, this review will discuss the clinical approach to patient with suspected AS, with particular emphasis on diagnosis and management of AS-ILD.

Increased long-term risk of heart failure and other adverse cardiac outcomes in dermatomyositis and polymyositis: Insights from a nationwide cohort

BACKGROUND

Mounting evidence suggests that dermatomyositis/polymyositis (DM/PM) are associated with increased risk of atherosclerotic events and venous thromboembolism. However, data on the association between DM/PM and other cardiac outcomes, especially heart failure (HF), are scarce.

OBJECTIVES

To examine the long-term risk and prognosis associated with adverse cardiac outcomes in patients with DM/PM.

METHODS

Using Danish administrative registries, we included all patients ≥18 years with newly diagnosed DM/PM (1996-2018). Risks of incident outcomes were compared with non-DM/PM controls from the background population (matched 1:4 by age, sex, and comorbidity). In a secondary analysis, we compared mortality following HF diagnosis between DM/PM patients with HF and non-DM/PM patients with HF (matched 1:4 by age and sex).

RESULTS

The study population included 936 DM/PM patients (median age 58.5 years, 59.0% women) and 3744 matched non-DM/PM controls. The median follow-up was 6.9 years. Absolute 10-year risks of incident outcomes for DM/PM patients vs matched controls were as follows: HF, 6.98% (CI, 5.16-9.16%) vs 4.58% (3.79-5.47%) (P = 0.002); atrial fibrillation, 10.17% (7.94-12.71%) vs 7.07% (6.09-8.15%) (P = 0.005); the composite of ICD implantation/ventricular arrhythmias/cardiac arrest, 1.99% (1.12-3.27%) vs 0.64% (0.40-0.98%) (P = 0.02); and all-cause mortality, 35.42% (31.64-39.21%) vs 16.57% (15.10-18.10%) (P < 0.0001). DM/PM with subsequent HF was associated with higher mortality compared with HF without DM/PM (adjusted hazard ratio 1.58 [CI, 1.01-2.47]).

CONCLUSION

Patients with DM/PM had a higher associated risk of HF and other adverse cardiac outcomes compared with matched controls. Among patients developing HF, a history of DM/PM was associated with higher mortality.

An update on the pathogenic role of IL-6 in rheumatic diseases

Interleukin (IL)-6 is a pleiotropic cytokine that is involved in the pathogenesis of various rheumatic diseases. Direct inhibition of the IL-6 pathway by an anti-IL-6 receptor or inhibiting the ligand itself has proved to be efficacious in the treatment of these diseases. Juvenile idiopathic arthritis, adult-onset Still's disease, large vessel vasculitis including giant cell arteritis and Takayasu disease, systemic sclerosis, and polymyalgia rheumatica respond well to IL-6 inhibition as expected. However, no clinically meaningful effect has been observed with regard to IL-6 blockade in ankylosing spondylitis, psoriatic arthritis, and systemic lupus erythematosus. This review discusses the current state of IL-6 targeting approaches in various rheumatic diseases other than rheumatoid arthritis.

MicroRNA-409-3p regulates macrophage migration in polymyositis through targeting CXCR4

BACKGROUND

Macrophage migration and infiltration contribute to the pathogenesis of polymyositis (PM). This study aims to investigate the effect and underlying mechanism of miR-409-3p on macrophage migration in PM.

METHODS

The GSE143845 database was used to predict the altered expression of microRNAs (miRNAs) in PM. The quantitative real-time PCR (qRT-PCR), western blot and Transwell assay were performed to detect migration of macrophages and expressions of related molecules. A luciferase activity assay was conducted to confirm the binding of miR-409-3p and CXCR4 3'-UTR. Next, a mouse model of experimental autoimmune myositis (EAM) was established. Haematoxylin and eosin (HE) staining, immunohistochemistry (IHC), and enzyme-linked immunosorbent assay (ELISA) were used to measure associated factors.

RESULTS

MiR-409-3p was downregulated in PM of GSE143845 database and patients. Differently, the serum creatine kinase (s-CK), TNF-α, and IL-6 in patients with PM were increased. Furthermore, miR-409-3p mimic transfection reduced the migration of macrophages and CXCR4 levels, while miR-409-3p inhibitor exerted the opposite effects. CXCR4 was a target of miR-409-3p, and the effect of CXCR4 on promoting macrophage migration was reversed by miR-409-3p mimic. In vivo, miR-409-3p agomir injection reduced inflammatory cells, macrophages, and TNFα and IL-6 levels in muscles and serum of EAM mouse models.

CONCLUSIONS

In conclusion, miR-409-3p reduces the migration of macrophages through negatively regulating CXCR4 expression in PM.

Decreased Muscular Perfusion in Dermatomyositis: Initial Results Detected by Inflow-Based Vascular-Space-Occupancy MRI

OBJECTIVE. This study aimed to determine whether inflow-based vascular-space-occupancy (iVASO) MRI could reproducibly quantify skeletal muscle perfusion and differentiate patients with dermatomyositis (DM) from healthy subjects. MATERIALS AND METHODS. A total of 25 patients with DM and 22 healthy volunteers underwent iVASO MRI in a 3-T MRI scanner. Maximum and mean arteriolar muscle blood volume (MBV) values of four subgroups of muscles (normal muscles, morphologically normal-appearing muscles, edematous muscles, and atrophic or fat-infiltrated muscles) were obtained. Maximum and mean arteriolar MBV values were compared among the different subgroups, and repeat testing was performed in 20 subjects to assess reproducibility. RESULTS. Compared with normal muscles in healthy subjects, morphologically normal-appearing muscles, edematous muscles, and atrophic or fat-infiltrated muscles in patients with DM showed a significant decrease of both maximum and mean arteriolar MBV (p < .001). Both parameters were significantly lower in atrophic or fat-infiltrated muscles than in morphologically normal-appearing and edematous muscles (p < .001). ROC AUCs for discriminating patients with DM from healthy volunteers were 0.842 and 0.812 for maximum and mean arteriolar MBV values, respectively. As a measure of test-retest studies, the intraclass correlation coefficients (ICCs) were 0.990 (95% CI, 0.986-0.993) and 0.990 (95% CI, 0.987-0.993) for maximum and mean arteriolar MBV, respectively. For interobserver reproducibility, the ICCs were 0.989 (95% CI, 0.986-0.991) and 0.980 (95% CI, 0.975-0.983), respectively. CONCLUSION. iVASO MRI can reproducibly quantify arteriolar MBV in the thigh and discriminate between healthy volunteers and patients with DM.

Reappraisal of the incidence, various types and risk factors of malignancies in patients with dermatomyositis and polymyositis in Taiwan

Our study aimed to investigate the incidence, risk factors and time to occurrence of malignancy in patients with dermatomyositis (DM) and polymyositis (PM). The electronic medical records of 1100 patients with DM and 1164 patients with PM were studied between January 2001 and May 2019. Malignancies after myositis were diagnosed in 61 (5.55%) patients with DM and 38 (3.26%) patients with PM. The cumulative incidence of malignancies in patients with DM were significantly higher than patients with PM (hazard ratio = 1.78, log-rank p = 0.004). Patients with DM had a greater risk of developing malignancy than those with PM at 40–59 years old (p = 0.01). Most malignancies occurred within 1 year after the initial diagnosis of DM (n = 35; 57.38%). Nasopharyngeal cancer (NPC) was the most common type of malignancy in patients with DM (22.95%), followed by lung, and breast cancers. In patients with PM, colorectal, lung and hepatic malignancies were the top three types of malignancy. The risk factors for malignancy included old age (≥ 45 years old) and low serum levels of creatine phosphokinase (CPK) for patients with DM and male sex and low serum levels of CPK for patients with PM. Low serum levels of CPK in patients with myositis with malignancy represented a low degree of muscle destruction/inflammation, which might be attributed to activation of the PD-L1 pathway by tumor cells, thus inducing T-cell dysfunction mediating immune responses in myofibers. A treatment and follow-up algorithm should explore the occurrence of malignancy in different tissues and organs and suggested annual follow-ups for at least 5.5 years to cover the 80% cumulative incidence of malignancy in patients with DM and PM.

Patient-reported dermatomyositis and polymyositis flare symptoms are associated with disability, productivity loss, and health care resource use

BACKGROUND: Flare activity or worsening symptoms are not well defined for myositis. OBJECTIVES: To (a) characterize dermatomyositis (DM) and polymyositis (PM) flares from the patient perspective and (b) report the corresponding disability and rate of unplanned medical encounters. METHODS: Online survey data were collected from volunteer patients from The Myositis Association and Johns Hopkins Myositis Center. Flare frequency; Health Assessment Questionnaire Disability Index (HAQ-DI), HAQ-Pain Index, Work Productivity and Activity Impairment (WPAI) scales; emergency department/urgent care (ED/UC) visits; and hospital admissions during the past year were examined. RESULTS: 564 individuals with selfreported diagnoses of DM/PM were surveyed between December 2017 and May 2018. Recall of symptom flares was reported by 524 respondents (78.1% were female, mean age of 55 years). Among the respondents, 378 (72.1%) reported ≥ 1 flare in the past year. The pattern of flare frequency was similar for DM and PM respondents. The most common symptoms were muscle weakness (83%), extreme fatigue (78%), and muscle pain/discomfort (64%). Increasing flare frequency was associated with significantly (P < 0.01) greater mean HAQ-DI and HAQ-Pain scores, myositis-related ED/UC visits, hospital admissions, WPAI work productivity loss (among those employed), and WPAI nonwork activity impairment. CONCLUSIONS: DM/PM-related flares are common with exacerbations of muscle weakness and fatigue being the most common flare symptoms. Flare frequency was associated with greater disability, pain, work productivity loss, nonwork activity impairment, and increased ED/UC utilization. Higher frequency of patient-reported flares may serve as a marker of worsening physical functioning and intensifying health care needs and, therefore, suggests their importance in the clinical assessment of patients with DM/PM. DISCLOSURES: This study was supported by Mallinckrodt Pharmaceuticals (Bedminster, NJ) via grants to Vedanta Research and The Myositis Association. Christopher-Stine has received compensation from previous Mallinckrodt Advisory Board meetings, unrelated to this subject matter. Wan is an employee of Mallinckrodt Pharmaceuticals and is a stockholder of the company. Reed and Bostic received grant support from Mallinckrodt Pharmaceuticals for data collection and analysis. McGowan is an employee of The Myositis Foundation, which received grant funding to support study data collection. Kelly has no conflicts to disclose. This study was presented, in part or full, at the 2019 Annual American College of Rheumatology and Association of Rheumatology Professional Meeting (November 8-13, 2018; Atlanta, GA) and at the Third Global Conference on Myositis (March 27, 2019; Berlin, Germany).

Reduced miR-146a Promotes REG3A Expression and Macrophage Migration in Polymyositis and Dermatomyositis

Background: Growing evidence from studies elsewhere have illustrated that microRNAs (miRNAs) play important roles in polymyositis and dermatomyositis (PM/DM). However, little has been reported on their relationship with regenerating islet-derived protein 3-alpha (REG3A) as well as their associative roles in macrophage migration. Therefore, this study sought to establish the association between miR-146a and REG3A as well as investigate their functional roles in macrophage migration and PM/DM pathogenesis. Methods: Peripheral blood mononuclear cells (PBMCs) were isolated from PM/DM patients and healthy controls through density centrifugation. Macrophages were obtained from monocytes purified from PBMCs via differentiation before their transfection with miRNA or plasmids to investigate cell migration with transwell assay. An experimental autoimmune myositis murine model was used to investigate PM/DM. Real-time PCR and Western blot analysis were conducted to determine the expression levels of miR-146a, interferon gamma (IFN-γ), interleukin (IL)-17A, and REG3A. Results: The messenger RNA (mRNA) expression level of miR-146a markedly decreased, while the mRNA level of REG3A, IFN-γ, and IL-17A expression increased substantially in PBMCs from PM/DM patients compared with the healthy controls. The levels of IFN-γ and IL-17A in serum from PM/DM patients was much higher than the healthy controls. Immunohistochemistry analysis showed that REG3A expression increased in muscle tissues from patients. Consistent with clinical data, the mRNA expression level of miR-146a also decreased, whereas the mRNA and protein level of REG3A, IFN-γ, and IL-17A significantly increased in the muscle tissues of experimental autoimmune myositis mice. Moreover, miR-146a inhibited monocyte-derived macrophage migration, and REG3A promoted macrophage migration. In addition, IL-17A induced REG3A expression, while miR146a inhibited expression of REG3A in monocyte-derived macrophages from the PBMCs of the healthy donors. Notably, inhibition of macrophage migration by miR-146a was via the reduction in REG3A expression. Conclusions: Reduced miR-146a expression in PM/DM leads to increased REG3A expression that increases inflammatory macrophage migration, which may be a possible underlying mechanism of DM/PM pathogenesis.

A Clinically and Biologically Based Subclassification of the Idiopathic Inflammatory Myopathies Using Machine Learning

OBJECTIVE

Published predictive models of disease outcomes in idiopathic inflammatory myopathies (IIMs) are sparse and of limited accuracy due to disease heterogeneity. Computational methods may address this heterogeneity by partitioning patients based on clinical and biological phenotype.

METHODS

To identify new patient groups, we applied similarity network fusion (SNF) to clinical and biological data from 168 patients with myositis (64 adult polymyositis [PM], 65 adult dermatomyositis [DM], and 39 juvenile DM [JDM]) in the Rituximab in Myositis trial. We generated a sparse proof-of-concept bedside classifier using multinomial regression and identified characteristics that distinguished these groups. We conducted χ² tests to link new patient groups with the myositis subtypes.

RESULTS

SNF identified five patient groups in the discovery cohort that subdivided the myositis subtypes. The sparse multinomial regressor to predict patient group assignments (areas under the receiver operating characteristic curve = [0.78, 0.97]; areas under the precision-recall curve = [0.55, 0.96]) found that autoantibody enrichment defined four of these groups: anti-Mi-2, anti-signal recognition peptide (SRP), anti-nuclear matrix protein 2 (NXP2), and anti-synthetase (Syn). Depletion of immunoglobulin M (IgM) defined the fifth group. Each group was associated with one subtype, with adult DM being associated with anti-Mi-2 and anti-Syn autoantibodies, JDM being associated with anti-NXP2 autoantibodies, and adult PM being associated with IgM depletion and anti-SRP autoantibodies. These associations enabled us to further resolve the current myositis subtypes.

CONCLUSION

Using unsupervised machine learning, we identified clinically and biologically homogeneous groups of patients with IIMs, forming the basis of an integrated disease classification based on both clinical and biological phenotype, thus validating other approaches and what has been previously described.

A Case of Refractory Polymyositis Successfully Treated With Abatacept Monotherapy

Polymyositis (PM) is an autoimmune disease progressing in the form of a break down of the muscles that is induced by chronic inflammation in skeletal muscles. Muscle weakness is painless and concentrates on proximal muscles, involving the pectoral and pelvic girdle. If the disease is not treated properly, it may progress and lead to a considerable decrease in the quality of life. Its conventional treatment involves drugs that suppress inflammation such as steroids, methotrexate, azathioprine, and intravenous immunoglobulin. However, conventional treatment may prove insufficient to halt the progression of the disease and offer only a limited improvement because of the adverse effects it causes in some patients. In this article, we present a 48-year-old female patient diagnosed with PM nearly 13 years ago that did not sufficiently respond to the pharmaceutical agents that were indicated for the conventional treatment of the disease and developed femoral head avascular necrosis because of the treatment and was, in the end, successfully treated with abatacept monotherapy at our clinic.

A rare form of dermatomyositis associated with muscle weakness and normal creatine kinase level

We present a case study of a 61-year-old Vietnamese woman who presents with features of dermatomyositis (DM), including Gottron’s papules, heliotrope rash, cutaneous ulcers, generalised weakness and pain, and weight loss with normal levels of creatine kinase (CK). She demonstrated features of interstitial lung disease and subsequently tested positive for anti-melanoma differentiation-associated gene 5 and anti-small ubiquitin-like modifier 1 activating enzyme antibodies, which belong to a DM subtype known as clinically amyopathic dermatomyositis and do not present with raised CK. She received standard treatment for DM, including oral prednisolone, hydroxychloroquine, mycopheonlate and topical betamethasone. The treatment successfully reversed skin changes; however, the patient remained generally weak and unable to carry out her activities of daily living.

Myositis Specific Autoantibodies: A Clinical Perspective

Dermatomyositis (DM) is an idiopathic inflammatory condition characterized by myositis and variable skin manifestation. The existence of myositis specific autoantibodies usually manifests with varying degrees of skin or muscle inflammations. The condition has a well-established association with most clinical phenotypes, and these autoantibodies are useful in informing the diagnosis, management and prognosis of the disease. DM-specific autoantibodies include anti-MDA5, anti-NXP2, anti-SAE, anti-Mi-2, anti-ARS, anti-TIF1-gamma. Anti-Mi-2 antibodies are widely associated with DM cases that exhibit mainly cutaneous symptoms, such as cuticular overgrowths, Gottron's papules while being less susceptible to complications like interstitial lung disease or malignancy. The most distinct clinical features of patients with anti-SAE antibodies are their high prevalence of dysphagia and cutaneous manifestations that antecede the development of myopathies. In addition, DM patients with positive anti-PL-7 antibodies tend to have milder myositis characterized by low levels of creatine kinase as compared to patients with positive anti-Jo-1 antibodies. The anti-NXP2 antibodies are associated with transcriptional regulation and production of various proteins targeted by other DM antibodies, while anti- TIF1-γ. facilitates the transcription of deoxyribonucleic acids and regulates the growth and subsequent differentiation of body cells by controlling the signaling of TGF-β. The present review targets DM specific autoantibodies, considering their association, significance, and clinical presentation.

Acute Kidney Injury Following Dermatomyositis

Renal involvement in patients with inflammatory myopathies, like dermatomyositis, is rare. We present the case of a woman, aged 66 years, who arrived at the hospital with acute renal failure. She had a diffuse erythematous rash, severe muscle weakness and decreased motor capacity. Inflammatory features of the skin/muscle biopsy along with the dramatic improvement in symptomatology upon the intake of steroids pointed towards dermatomyositis. Recognition of this pattern of events, adopting a multidisciplinary approach, early diagnosis and steroid treatment are necessary for better patient outcomes.

Antinuclear Antibody Tests

The presence of antinuclear antibodies (ANAs), which include autoantibodies to extractable nuclear antigens (ENAs), in the sera of patients with connective tissue diseases provides useful immunologic and pathophysiologic insight into the nature of their disease. This article discusses the most commonly used diagnostic modalities for detecting and quantitating the presence of ANA: indirect immunofluorescence assay, enzyme-linked immunosorbent assay, and multiplex bead technology, which serve as useful screening tests. We also review testing for autoantibodies to ENAs, which are often helpful to confirm the diagnosis of a specific connective tissue disease.

Meta-Analysis of Polymyositis and Dermatomyositis Microarray Data Reveals Novel Genetic Biomarkers

Polymyositis (PM) and dermatomyositis (DM) are both classified as idiopathic inflammatory myopathies. They share a few common characteristics such as inflammation and muscle weakness. Previous studies have indicated that these diseases present aspects of an auto-immune disorder; however, their exact pathogenesis is still unclear. In this study, three gene expression datasets (PM: 7, DM: 50, Control: 13) available in public databases were used to conduct meta-analysis. We then conducted expression quantitative trait loci analysis to detect the variant sites that may contribute to the pathogenesis of PM and DM. Six-hundred differentially expressed genes were identified in the meta-analysis (false discovery rate (FDR) < 0.01), among which 317 genes were up-regulated and 283 were down-regulated in the disease group compared with those in the healthy control group. The up-regulated genes were significantly enriched in interferon-signaling pathways in protein secretion, and/or in unfolded-protein response. We detected 10 single nucleotide polymorphisms (SNPs) which could potentially play key roles in driving the PM and DM. Along with previously reported genes, we identified 4 novel genes and 10 SNP-variant regions which could be used as candidates for potential drug targets or biomarkers for PM and DM.

Autoantibodies in Myositis. How to Achieve a Comprehensive Strategy for Serological Testing

Myopathies are a rare type of acquired, chronic autoimmune diseases of the skeletal muscles and affect both children and adults. The hallmark symptoms of idiopathic inflammatory myopathies (IIM) are muscle inflammation, proximal muscle weakness and disability, arthritis, cutaneous rashes, calcinosis, ulceration, malignancy and interstitial lung disease (ILD). Subforms of IIM include polymyositis, dermatomyositis, cancer-related myositis and sporadic inclusion body myositis. Autoantibodies function as biomarkers for diagnosis of IIM and can be used to delimit clinically distinguishable IIM subforms. To maximise the diagnostic information it is essential to perform comprehensive multiparametric serological testing including both screening and confirmation tests.

Disorders of the Diaphragm

Pathologic processes that involve the central nervous system, phrenic nerve, neuromuscular junction, and skeletal muscle can impair diaphragm function. When these processes are of sufficient severity to cause diaphragm dysfunction, respiratory failure may be a consequence. This article reviews basic diaphragm anatomy and physiology and then discusses diagnostic and therapeutic approaches to disorders that result in unilateral or bilateral diaphragm dysfunction. This discussion provides a context in which disorders of the diaphragm and their implications on respiratory function can be better appreciated.

ANGPTL3: a novel biomarker and promising therapeutic target

Angiopoietin-like protein 3 (ANGPTL3) belongs to a multifunctional secreted protein that mainly expresses in the liver, and is regulated by numerous post-translational modifications, including multiple cleavage and glycosylation. Accumulating evidences have revealed that ANGPTL3 plays a critical role in both biological processes, such as lipid metabolism, angiogenesis and haematopoietic function and pathological changes, including atherosclerosis, carcinogenesis, nephrotic syndrome, diabetes, liver diseases and so on. Thus, ANGPTL3 may serve as a potential biomarker in these diseases. Furthermore, ANGPTL3 signalling pathways including LXR/ANGPTL3, thyroid hormone/ANGPTL3, insulin/ANGPTL3 and leptin/ANGPTL3 are also involved in physiological and pathological processes. Some biological ANGPTL3 inhibitors, chemical drugs and traditional Chinese medicine exert beneficial effects by targeting ANGPTL3 directly or indirectly. Therefore, elucidating the effects and underlying mechanisms of ANGPTL3 is essential to develop promising strategies in the diagnosis and treatment of related diseases.

Discovery of Key Genes in Dermatomyositis Based on the Gene Expression Omnibus Database

The aim of this study was to identify biomarkers of dermatomyositis (DM). The analysis was conducted by retrieving DM-related cDNA microarray data sets from public databases. Gene ontology, Kyoto encyclopedia of genes and genomes, and protein-protein interaction analyses were performed, together with quantitative PCR-based detection of biomarkers in muscle tissue after stimulation with serum from patients with DM or healthy controls. Our analysis of five microarray data sets identified 20 common differentially expressed genes that are closely associated with DM. PCR analysis showed that mRNAs of IFITM2, LY6E, DDX58, and IFI6 were expressed at significantly higher levels in the muscle tissue of patients with DM than in normal muscle tissues. These mRNAs were also upregulated in human skeletal muscle cells stimulated with the serum from patients with DM. The results of integrated analyses of the DM microarray data and the mRNA levels of genes showed significant differences between the muscle tissues of DM patients and controls, which could indicate key pathogenic genes and novel therapeutic targets for DM.

Dermatomyositis etiopathogenesis: a rebel soldier in the muscle

PURPOSE OF REVIEW

The purpose of this article is to review the etiopathogenesis of dermatomyositis, including the predisposing factors, triggers, inflammatory cells, pathways and target antigens associated with dermatomyositis.

RECENT FINDINGS

During the last few years, we have made considerable progress in unveiling the etiopathogenesis of dermatomyositis. In the first place, we have defined genes within the major histocompatibility complex locus as the greatest genetic risk factor for the disease. Second, we have demonstrated that certain environmental factors, as well as tumors, may trigger certain dermatomyositis subtypes. Moreover, we have established the importance of the interferon pathway in dermatomyositis pathogenesis compared with other myositis subtypes. But probably, the most remarkable advance has been the discovery of multiple autoantibodies that define groups of patients with characteristic clinical features, prognosis and response to treatment.

SUMMARY

Dermatomyositis cause and pathogenesis have proven to be a complex and fascinating task for the scientific community and the last decade has been full of new findings on how the disease starts and how it causes damage to different organ systems. However, we have still more questions than answers in this topic, answers that will be critical to understanding autoimmunity and finding effective therapies to dermatomyositis.

Clinical Profiles and Prognosis of Patients with Distinct Antisynthetase Autoantibodies

OBJECTIVE

To compare the clinical characteristics and identify the longterm outcomes of Chinese patients with different antisynthetase antibodies.

METHODS

We investigated retrospectively 124 consecutive patients with antisynthetase syndrome. Medical records, laboratory results, and computed tomography images were obtained.

RESULTS

The antisynthetase antibodies we investigated were anti-Jo1 (n = 62), anti-PL7 (n = 31), anti-PL12 (n = 12), and anti-EJ (n = 19). The overall prevalence of interstitial lung disease (ILD) reached 94.4% among study patients. Eleven patients (8.9%) developed rapidly progressive ILD (RP-ILD). Eight patients (6.5%) experienced malignancy. RP-ILD was statistically more prevalent in patients with antisynthetase syndrome with anti-PL7 than those without anti-PL7 (p = 0.028). Anti-Ro52-positive patients with antisynthetase syndrome experienced higher frequency of RP-ILD than those without anti-Ro52 (p = 0.001). Further, anti-PL7-positive patients coexisting with anti-Ro52 exhibited more RP-ILD than those without anti-Ro52 (p = 0.001). Patients with antisynthetase syndrome with RP-ILD had a higher proportion of neutrophils in bronchoalveolar lavage fluid and serum ferritin than those without RP-ILD (p = 0.006 and p = 0.013, respectively). Although no differences were observed between the Kaplan-Meier curves of the 4 antisynthetase antibodies subgroups (p = 0.349), the survival rate of patients with anti-PL7 decreased more rapidly in the early stage of longterm followup compared with those with other antisynthetase antibodies. The presence of RP-ILD, malignancy, and elevated serum ferritin was identified to be associated with poor prognosis in patients with antisynthetase syndrome.

CONCLUSION

Our study investigates the clinical phenotypes and outcomes of patients with antisynthetase syndrome with distinct antisynthetase antibodies and highlights the link between the anti-PL7 antibody and RP-ILD.

In vivo measurement of membrane permeability and myofiber size in human muscle using time-dependent diffusion tensor imaging and the random permeable barrier model

The time dependence of the diffusion coefficient is a hallmark of tissue complexity at the micrometer level. Here we demonstrate how biophysical modeling, combined with a specifically tailored diffusion MRI acquisition performing diffusion tensor imaging (DTI) for varying diffusion times, can be used to determine fiber size and membrane permeability of muscle fibers in vivo. We describe the random permeable barrier model (RPBM) and its assumptions, as well as the details of stimulated echo DTI acquisition, signal processing steps, and potential pitfalls. We illustrate the RPBM method on a few pilot examples involving human subjects (previously published as well as new), such as revealing myofiber size derived from RPBM increase after training in a calf muscle, and size decrease with atrophy in shoulder rotator cuff muscle. Finally, we comment on the potential clinical relevance of our results. Copyright © 2016 John Wiley & Sons, Ltd.

Idiopathic Inflammatory Myopathies and Malignancy: a Comprehensive Review

The idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of autoimmune diseases (collectively known as myositis) affecting the skeletal muscles as well as other organ systems such as skin, lungs, and joints. The primary forms of myositis include polymyositis (PM), dermatomyositis (PM), and immune-mediated necrotizing myopathy (IMNM). Patients with these diseases experience progressive proximal muscle weakness, have characteristic muscle biopsy findings, and produce autoantibodies that are associated with unique clinical features. One distinguishing feature of these patients is that they are also known to have an increased risk of cancer. Since the first description of the association in 1916, it has been extensively reported in the medical literature. However, there have been significant variations between the different studies with regard to the degree of cancer risk in patients with IIM. These discrepancies can, in part, be attributed to differences in the definition of malignancy-associated myositis used in different studies. In recent years, significant advances have been made in defining specific features of IIM that are associated with the development of malignancy. One of these has been myositis-specific antibodies (MSAs), which are linked to distinct clinical phenotypes and categorize patients into groups with more homogeneous features. Indeed, patients with certain MSAs seem to be at particularly increased risk of malignancy. This review attempts a systematic evaluation of research regarding the association between malignancy and myositis.

Antimelanoma differentiation-associated protein 5 antibody level is a novel tool for monitoring disease activity in rapidly progressive interstitial lung disease with dermatomyositis

BACKGROUND

Antimelanoma differentiation-associated protein (anti-MDA)5 antibodies are associated with rapidly progressive interstitial lung disease (RP-ILD) in patients with clinically amyopathic dermatomyositis (CADM) or dermatomyositis (DM).

OBJECTIVES

We aimed to evaluate the relevance of monitoring anti-MDA5 antibody levels for the management of RP-ILD in patients with CADM or DM.

METHODS

Twelve patients with CADM (n = 10) or DM (n = 2) accompanied by RP-ILD were included. Baseline characteristics and outcomes were recorded. Serial measurements of anti-MDA5 antibody levels were measured. All patients were treated with corticosteroids, tacrolimus and intravenous cyclophosphamide.

RESULTS

All patients achieved RP-ILD remission after combined immunosuppressive therapy for a mean of 6·8 months, with significant decreases noted in the mean anti-MDA5 antibody levels at remission. Six (50%) patients became anti-MDA5 antibody negative after therapy. After a mean follow-up of 31 months, RP-ILD relapse was observed in four (33%) patients in both the anti-MDA5 antibody sustained positive group and the negative conversion group. However, relapsed patients in the sustained positive group relapsed earlier than those in the negative conversion group. Thus, a decrease in anti-MDA5 antibody levels during remission was associated with longer remission. Relapses were associated with a reincrease of anti-MDA5 antibody levels in four of four (100%) patients. In contrast, none of the patients without reincrease in anti-MDA5 antibody exhibited symptoms of relapse during follow-up. Therefore, reincrease in anti-MDA5 antibody levels was associated with relapse.

CONCLUSIONS

The anti-MDA5 antibody level is a novel parameter for monitoring and a good predictor of RP-ILD relapse in patients with CADM or DM.

A Negative Antinuclear Antibody Does Not Indicate Autoantibody Negativity in Myositis: Role of Anticytoplasmic Antibody as a Screening Test for Antisynthetase Syndrome

Objective.

To evaluate the utility of anticytoplasmic autoantibody (anti-CytAb) in antisynthetase antibody–positive (anti-SynAb+) patients.

Methods.

Anti-SynAb+ patients were evaluated for antinuclear antibody (ANA) and anti-CytAb [cytoplasmic staining on indirect immunofluorescence (IIF)] positivity. Anti-SynAb+ patients included those possessing anti-Jo1 and other antisynthetase autoantibodies. Control groups included scleroderma, systemic lupus erythematosus, Sjögren syndrome, rheumatoid arthritis, and healthy subjects. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy of anti-CytAb, and ANA were assessed. Anti-CytAb and ANA testing was done by IIF on human epithelial cell line 2, both reported on each serum sample without knowledge of the clinical diagnosis or final anti-SynAb results.

Results.

Anti-SynAb+ patients (n = 202; Jo1, n = 122; non-Jo1, n = 80) between 1985–2013 with available serum samples were assessed. Anti-CytAb showed high sensitivity (72%), specificity (89%), NPV (95%), and accuracy (86%), but only modest PPV (54%) for anti-SynAb positivity. In contrast, ANA showed only modest sensitivity (50%) and poor specificity (6%), PPV (9%), NPV (41%), and accuracy (12%). Positive anti-CytAb was significantly greater in the anti-SynAb+ patients than ANA positivity (72% vs 50%, p < 0.001), and 81/99 (82%) ANA-negative patients in the anti-SynAb+ cohort had positive anti-CytAb. In contrast, the control groups showed high rates for ANA positivity (93.5%), but very low rates for anti-CytAb positivity (11.5%). Combining anti-CytAb or Jo1 positivity showed high sensitivity (92%) and specificity (89%) for identification of anti-SynAb+ patients.

Conclusion.

Assessing patients for anti-CytAb serves as an excellent screen for anti-SynAb+ patients using simple IIF. Cytoplasmic staining should be assessed and reported for patients suspected of having antisynthetase syndrome and a negative ANA should not be used to exclude this diagnosis.

The sphingosine-1-phosphate receptor: A novel therapeutic target for multiple sclerosis and other autoimmune diseases

Multiple sclerosis (MS) is a prototype autoimmune disease of the central nervous system (CNS). Currently, there is no drug that provides a cure for MS. To date, all immunotherapeutic drugs target relapsing remitting MS (RR-MS); it remains a daunting medical challenge in MS to develop therapy for secondary progressive MS (SP-MS). Since the approval of the non-selective sphingosine-1-phosphate (S1P) receptor modulator FTY720 (fingolimod [Gilenya®]) for RR-MS in 2010, there have been many emerging studies with various selective S1P receptor modulators in other autoimmune conditions. In this article, we will review how S1P receptor may be a promising therapeutic target for SP-MS and other autoimmune diseases such as psoriasis, polymyositis and lupus.

Serum concentrations of Flt-3 ligand in rheumatic diseases

Fms-like tyrosine kinase 3 (Flt-3) is a cytokine receptor expressed on the surface of bone-marrow progenitor of hematopoietic cells. Flt-3 ligands are produced by peripheral blood mononuclear cells, and found in various human body fluids. Flt-3 signal is involved in the regulation of vessel formation as well as B cell differentiation, suggesting that Flt-3 signal contributes to the pathogenesis of vascular abnormalities and immune dysregulation in rheumatic diseases. The aim of the present study is to examine serum Flt-3 ligand levels in patients with various rheumatic diseases, and to evaluate the possibility that serum Flt-3 ligand levels can be a useful disease marker. Sera were obtained from 20 dermatomyositis (DM) patients, 36 systemic sclerosis (SSc) patients, 10 systemic lupus erythematosus (SLE) patients, 10 scleroderma spectrum disorder (SSD) patients, 4 mixed connective tissue disease (MCTD) patients, and 12 normal subjects. Flt-3 ligand levels were determined with ELISA. Serum Flt-3 ligand levels were significantly elevated in patients with DM, SSc, SSD and MCTD compared to those in normal subjects. DM patients with elevated Flt-3 ligand levels were accompanied with significantly increased CRP levels and increased frequency of heliotrope rash than those with normal levels. In addition, SSc patients with elevated Flt-3 ligand levels showed significantly reduced frequency of nailfold bleeding. Serum Flt-3 ligand levels can be a marker of cutaneous manifestation in DM and a marker of microangiopathy in SSc. Clarifying the role of Flt-3 ligand in rheumatic diseases may lead to further understanding of these diseases and new therapeutic approaches.

Isaacs' syndrome in a patient with dermatomyositis: case report and review of the literature

This is a case report of Isaacs' syndrome in dermatomyositis. The patient presented with proximal muscle weakness, rash, elevated muscle enzyme, myopathic electromyograph and typical muscle biopsy. Ultimately he developed typical symptoms of Isaacs' syndrome which is an autoimmune channelopathy from voltage gated potassium channel antibody (anti-VGKC) leading to dysfunction of axonal discharge at neuromuscular junctions. It shares some similar characteristics with dermatomyositis such as autoimmunity, its association with malignancy and the response to treatment.

Idiopathic inflammatory myopathies and the lung

Idiopathic inflammatory myositis (IIM) is a group of rare connective tissue diseases (CTDs) characterised by muscular and extramuscular signs, in which lung involvement is a challenging issue. Interstitial lung disease (ILD) is the hallmark of pulmonary involvement in IIM, and causes morbidity and mortality, resulting in an estimated excess mortality of 50% in some series. Except for inclusion body myositis, these extrapulmonary disorders are associated with the general and visceral involvement frequently found in other CTDs including fever, Raynaud's phenomenon, arthralgia, nonspecific cutaneous modifications and ILD, for which the prevalence is estimated to be up to 65%. Substantial heterogeneity exists within the spectrum of IIMs, and each condition is associated with various frequencies and subtypes of pulmonary involvement. This heterogeneity is partly related to the presence of various autoantibodies encompassing anti-synthetase, anti-MDA5 and anti-PM/Scl. ILD is present in all subsets of IIM including juvenile myositis, but is more frequent in dermatomyositis and overlap myositis. IIM can also be associated with other presentations of respiratory involvement, namely pulmonary arterial hypertension, pleural disease, infections, drug-induced toxicity, malignancy and respiratory muscle weakness. Here, we critically review the current knowledge about adult and juvenile myositis-associated lung disease with a detailed description of therapeutics for chronic and rapidly progressive ILD.

Case Report: Elevated CPK, an indicator of idiopathic inflammatory myopathy?

Polymyositis is a rare disease with incidence rates at about 1 per 100,000 people annually. In this case report we will review a case of proximal muscle weakness with an elevated creatine phosphokinase that was initially misdiagnosed twice as rhabdomyolysis. Therefore, emphasizing that idiopathic inflammatory myopathy is a potential cause of myasthenia that must be considered in the differential. The case will also describe the current treatment and treatment response in polymyositis.

Gene Expression Profile of Inflammatory Myopathy with Malignancy is Similar to that of Dermatomyositis rather than Polymyositis

Objective An association has been reported between inflammatory myopathies (IMs), which include polymyositis (PM) and dermatomyositis (DM), and malignancy, and the concept of cancer-associated myositis (CAM) was recently proposed. We herein attempted to determine the features and etiologies of these myopathies. Methods We analyzed the gene expression levels via microarray and real-time quantitative reverse transcription polymerase chain reaction analyses to identify genes that were specifically upregulated or downregulated with suspected inflammatory involvement and verified the microarray data via an immunohistochemical (IHC) analysis in additional cases. Patients We selected 14 patients with the following conditions: PM without malignancy (n=3), DM without malignancy (n=3), CAM (n=3), and Controls (no pathological changes or malignancy; n=5). Results PM was distinct from DM and CAM in a clustering analysis and exhibited the highest numbers of overexpressed genes and specific pathologies in a gene ontology analysis. The IHC analysis confirmed the gene expression results. Conclusion PM is associated with severe inflammatory pathological findings, primarily in the cell-mediated immune system. DM and CAM exhibit similarities in the gene expression and IHC results, which suggest that humoral immunity is the main etiology for both myopathies, indicating the importance of cancer screening in patients with IMs, particularly DM.