Genetic and environmental risk factors for idiopathic inflammatory myopathies

Myopathies of endocrine origin: A review for physicians

Myopathies are a common manifestation of endocrine disorders. Endocrine myopathies are often overlooked while considering differential diagnoses in patients with musculoskeletal symptoms. The hindrance to mobility and the musculoskeletal discomfort owing to these myopathies are important causes of disability and depreciated quality of life in these patients. Endocrine myopathies occur due to the effects of endogenous or iatrogenic hormonal imbalance on skeletal muscle protein and glucose metabolism, disrupting the excitation-contraction coupling. Abnormalities of the pituitary, thyroid, parathyroid, adrenal, and gonadal hormones have all been associated with myopathies and musculoskeletal symptoms. Endocrine myopathies can either be the complication of a secondary endocrine disorder or a presenting symptom of a missed underlying disorder. Therefore, an underlying endocrine abnormality must always be excluded in all patients with musculoskeletal symptoms. This review presents a compilation of various endocrine myopathies, their etiopathogenesis, clinical presentation, diagnostic modalities, and treatment protocols.

Polymyositis: A Case Report

Inflammatory myopathies are a group of diseases whose common pathway is immune-mediated muscle damage, one of which is polymyositis. The definition of polymyositis is controversial, with proponents advocating a definition based on immunohistochemical and histopathological findings in muscle biopsies, while other proponents advocate a definition based on clinical manifestations and histopathological findings. Polymyositis is a quite rare disease that is clinically characterized by progressive proximal muscle weakness with a symmetric distribution. Within the diagnostic approach, laboratory studies show elevation of sarcoplasmic enzymes; nerve conduction tests are performed, which may aid in distinguishing myopathic causes of weakness from neuropathic disorders; and muscle biopsy is considered the gold standard to diagnose inflammatory myopathy and to distinguish the subclasses. We report the case of a 61-year-old male patient who presented generalized symmetrical weakness, predominantly in the upper extremities, and dysphagia, whose laboratory studies, autoantibodies, and muscle biopsy were confirmatory of this entity.

Inflammatory myopathy following coronavirus disease 2019 vaccination: A systematic review

Introduction

Reports of unexpected side effects have accompanied the vaccination of larger proportions of the population against coronavirus disease 2019 (COVID-19), including a few cases of inflammatory myopathy (IM). In a bid to improve understanding of the clinical course of vaccine complications, a systematic review of reported cases of IM following COVID-19 vaccination has been conducted.

Methods

The PRISMA guideline 2020 was followed. Two independent investigators systematically searched PubMed and Embase to identify relevant studies published up to July 2022, using the following keywords: COVID-19 Vaccine, inflammatory myositis. The Joanna Briggs Institute critical appraisal tools were used for the risk of bias.

Results

A total of 24 articles presenting clinical features of 37 patients with IM following COVID-19 vaccine were identified. Female patients composed 59.5% of cases and 82.4% had been vaccinated with BNT162b2 or ChAdOx1. Onset of symptoms occurred within 2 weeks of the first or second vaccine dose in 29 (85.3%) patients and included muscular weakness in 54.1% and skin rash in 71.4% of patients. Myositis specific autoantibodies (MSAs) and myositis associated autoantibodies (MAAs) were reported in 28 patients. Specific clinical subtypes of myositis, reported in 27 patients, included 22 (81.5%) cases of dermatomyositis (DM) and 3 (11.1%) cases of immune-mediated necrotizing myopathy (IMNM). Following treatment, 32 (86.5%) patients showed improvement on follow-up.

Conclusion

COVID-19 vaccine may induce various clinical myositis subtypes and related antibodies. Muscular weakness was the most common presenting symptom. Clinicians should be aware of this unexpected adverse event following COVID-19 vaccination and arrange for appropriate management.

Systematic review registration

INPLASY https://inplasy.com/inplasy-2022-9-0084/ [INPLASY202290084].

Prevention of Adverse Outcomes and Treatment Side Effects in Patients with Neuromuscular Disorders

In this article, we review prevention of serious adverse clinical outcomes and treatment side effects in patients with neuromuscular disorders including myopathies and myasthenia gravis. While neither of these entities is preventable, their course can often be modified, and severe sequelae may be prevented, with the identification of risk factors and proactive attention toward treatment planning.

Dermatomyositis Following BNT162b2 mRNA COVID-19 Vaccination

Dermatomyositis (DM) is one of the uncommon multi-organ idiopathic inflammatory myopathies that has been reported following the hepatitis B, Influenza, tetanus toxoid, H1N1, and BCG vaccines. However, an association with the coronavirus disease 2019 (COVID-19) vaccine is yet to be reported. In this case, we present the case of a 43-year-old Asian Indian female who was diagnosed with DM 10 days after receiving the second dosage of BNT162b2 mRNA COVID-19 vaccination, in the absence of any additional triggering factors. The diagnosis was established based on physical examination, serological antibodies, magnetic resonance imaging of the muscles, skin biopsy, and electromyography. She received standard treatment for DM, including oral high doses of prednisolone, hydroxychloroquine, mycophenolate, and physiotherapy. The treatment successfully reversed skin changes and muscle weakness. This is the first reported case of classic DM complicated by interstitial lung disease following COVID-19 vaccination. More clinical and functional studies are needed to elucidate this association. Clinicians should be aware of this unexpected adverse event following COVID-19 vaccination and arrange for appropriate management.

Update on Myositis Therapy: from Today's Standards to Tomorrow's Possibilities

Inflammatory myopathies, in short, myositis, are heterogeneous disorders that are characterized by inflammation of skeletal muscle and weakness of arms and legs. Research over the past few years has led to a new understanding regarding the pathogenesis of myositis. The new insights include different pathways of the innate and adaptive immune response during the pathogenesis of myositis. The importance of non-inflammatory mechanisms such as cell stress and impaired autophagy has been recently described. New target-specific drugs for myositis have been developed and are currently being tested in clinical trials. In this review, we discuss the mechanisms of action of pharmacological standards in myositis and provide an outlook of future treatment approaches.

The altered metabolism profile in pathogenesis of idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIMs) are a group of heterogeneous autoimmune diseases characterized by muscle weakness, muscle inflammation and extramuscular manifestations. Despite extensive efforts, the mechanisms of IIMs remain largely unknown, and treatment is still a challenge for physicians. Metabolism changes have emerged as a crucial player in autoimmune diseases, such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). However, little is known about metabolism changes in IIMs. In this review, we focus on the alteration of metabolism profile in IIMs, and the relationships with clinical information. We highlight the potential roles of metabolism in the pathogenesis of IIMs and discuss future perspectives for metabolic checkpoint-based therapeutic interventions.

Integrated comparison of the miRNAome and mRNAome in muscles of dermatomyositis and polymyositis reveals common and specific miRNA–mRNAs

Aim: Dermatomyositis (DM) and polymyositis (PM) are refractory systemic autoimmune diseases with unknown pathogenesis. miRNAs is an important epigenetic mechanism to regulate gene expression. Methods: We performed whole miRNAs analysis, transcription analysis and the association between miRNAome and mRNAome. Results: For transcription and miRNAs analysis, there were common and specific mRNAs and miRNAs in the muscles of DM and PM. Among them, the expression levels of miR-196a-5p and CPM were negatively correlated in PM, miR-193b-3p and NECAP2 were negatively correlated in DM and PM. Protein carboxypeptidase M (CPM) plays roles in the degradation of extracellular proteins and in the migration and invasion of cancer cells, and protein NECAP2 plays roles in adaptor protein AP-1-mediated fast recycling from early endosomes. The functions of them in the pathogenesis of DM/PM need further studies. Conclusion: Our study identified and confirmed differentially miRNAs and mRNAs in DM and PM. Our observations have laid the groundwork for further diagnostic and mechanistic studies of DM and PM.

Risk factors and disease mechanisms in myositis

Autoimmune diseases develop as a result of chronic inflammation owing to interactions between genes and the environment. However, the mechanisms by which autoimmune diseases evolve remain poorly understood. Newly discovered risk factors and pathogenic processes in the various idiopathic inflammatory myopathy (IIM) phenotypes (known collectively as myositis) have illuminated innovative approaches for understanding these diseases. The HLA 8.1 ancestral haplotype is a key risk factor for major IIM phenotypes in some populations, and several genetic variants associated with other autoimmune diseases have been identified as IIM risk factors. Environmental risk factors are less well studied than genetic factors but might include viruses, bacteria, ultraviolet radiation, smoking, occupational and perinatal exposures and a growing list of drugs (including biologic agents) and dietary supplements. Disease mechanisms vary by phenotype, with evidence of shared innate and adaptive immune and metabolic pathways in some phenotypes but unique pathways in others. The heterogeneity and rarity of the IIMs make advancements in diagnosis and treatment cumbersome. Novel approaches, better-defined phenotypes, and international, multidisciplinary consensus have contributed to progress, and it is hoped that these methods will eventually enable therapeutic intervention before the onset or major progression of disease. In the future, preemptive strategies for IIM management might be possible.

The effect of cigarette smoking on the clinical and serological phenotypes of polymyositis and dermatomyositis

OBJECTIVE

Cigarette smoking is associated with immune-mediated disorders. We explored the contribution of smoking to polymyositis (PM) and dermatomyositis (DM) phenotypes and attempted to determine whether cigarette smoking effects differ by race and genotype.

METHODS

Associations of tobacco smoking with disease features, autoantibodies, HLA types, and race were evaluated using multiple logistic regressions in 465 patients.

RESULTS

Caucasian ever-smokers (n = 140) were more likely to have PM (adjusted OR = 2.24, 95% CI: 1.41\x963.57), anti-synthetase (adjusted OR = 1.93, 95% CI: 1.12\x963.34) and anti-Jo-1 autoantibodies (adjusted OR = 1.94, 95% CI: 1.08\x963.46) and less likely to have anti-p155/140 autoantibodies (adjusted OR = 0.36, 95% CI: 0.14\x960.92). In Caucasians, ever-smokers had a greater interstitial lung disease (ILD) frequency than never-smokers, while in African-Americans this relationship was inverted, but neither trend reached statistical significance. Pack-years of cigarette smoking showed significant positive associations with PM (adjusted OR = 1.02, 95% CI: 1.002\x961.04) and ILD (adjusted OR = 1.02, 95% CI: 1.001\x961.03) and was inversely associated with anti-p155/140 autoantibodies (adjusted OR = 0.93, 95% CI: 0.87\x960.99) in Caucasians. Caucasian heavy smokers (=20 pack-years) were more likely to have PM (adjusted OR = 2.52, 95% CI: 1.25\x965.09), ILD (adjusted OR = 2.48, 95% CI: 1.23\x965.00) and anti-Jo-1 autoantibodies (adjusted OR = 2.65, 95% CI: 1.16\x966.08) than never-smokers. In Caucasians, compared to never-smokers without HLA-DRB1*03:01 allele, ever-smokers with HLA-DRB1*03:01 allele had the highest odds of PM, ILD, ASA, and anti-Jo-1 autoantibodies. Risks for those with only one of these two factors were intermediate. An inverse pattern was observed regarding anti-p155/140 autoantibodies.

CONCLUSION

Tobacco smoking was associated with clinical and autoantibody phenotypes in Caucasians. Our findings also suggest possible interactions among HLA-DRB1*03:01 and smoking on the risk of PM and ILD, as well as, anti-synthetase, anti-Jo-1, and anti-p155/140 autoantibodies in Caucasians.

Statin-associated immune-mediated necrotising myopathy: a New Zealand case series showing possible overrepresentation in Pacific Islanders

BACKGROUND

Statin-associated immmune-mediated necrotising myopathy (IMNM) is an emerging entity. Being an uncommon condition, our knowledge and understanding is largely based on case series.

AIM

To review incident cases of statin-associated IMNM associated with anti-3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR) antibodies in a single New Zealand centre over a 2-year period.

METHODS

Four incident cases of statin-associated IMNM were seen between 2014 and 2016. Their presentation, investigation, treatment and current response to treatment are summarised. Two of the four patients were Pacific Islanders despite a small Pacific Island population in the southern district health board. A literature search was performed focusing on the presentation, investigation and treatment of statin-associated IMNM and also genetic associations with this entity to determine whether Pacific Islanders may be at increased risk RESULTS: All four patients presented with profound weakness and recent exposure to atorvastatin. All proceeded to muscle biopsy. Two biopsies showed typical IMNM. One biopsy had mild changes, reported as possibly being compatible with anti-HMGCR antibodies. The final biopsy had features consistent with IMNM, with some features suggestive of polymyositis. Two recent studies have shown an association between anti-HMGCR antibodies and the HLA-DRB1*11:01 haplotype. Interestingly, HLA-DRB1 alleles (including HLA-DRB1*11:01) were observed to be among the most frequent alleles in a Pacific Island population study.

CONCLUSION

This is the first case series of statin-associated IMNM with a focus on Pacific Islanders and raises the possibility that Pacific Islanders exposed to statins may be at increased risk of developing an immune-mediated myopathy.

Bioinformatics analysis of gene expression profiles of dermatomyositis

Dermatomyositis (DM) is a type of autoimmune inflammatory myopathy, which primarily affects the skin and muscle. The underlying mechanisms of DM remain poorly understood. The present study aimed to explore gene expression profile alterations, investigate the underlying mechanisms, and identify novel targets for DM. The GSE48280 dataset, which includes data from five DM and five normal muscle tissue samples, was obtained from the Gene Expression Omnibus. Firstly, differentially expressed genes (DEGs) were screened by limma package in R. Subsequently, functional and pathway enrichment analyses were performed using ClueGO from Cytoscape. Finally, protein‑protein interaction (PPI) networks were constructed using STRING and Cytoscape, in order to identify hub genes. As a result, 180 upregulated and 21 downregulated genes were identified in the DM samples. The Gene Ontology enrichment analysis revealed that the type I interferon (IFN) signaling pathway was the most significantly enriched term within the DEGs. The Kyoto Encyclopedia of Genes and Genomes pathway analysis identified 27 significant pathways, the majority of which can be divided into the infectious diseases and immune system categories. Following construction of PPI networks, 24 hub genes were selected, all of which were associated with the type I IFN signaling pathway in DM. The findings of the present study indicated that type I IFNs may have a central role in the induction of DM. In addition, other DEGs, including chemokine (C‑C motif) ligand 5, C‑X‑C motif chemokine 10, Toll‑like receptor 3, DEXD/H‑Box helicase 58, interferon induced with helicase C domain 1, interferon‑stimulated gene 15 and MX dynamin‑like GTPase 1, may be potential targets for DM diagnosis and treatment.

Inflammatory myopathies and lymphoma

The inflammatory myopathies comprise a group of immune-mediated muscle diseases. Lymphoma is a term for a variety of lymphatic system malignancies. Autoimmune diseases and lymphoproliferative malignancies share a complex bidirectional relationship. A causal relationship between inflammatory mypathies and lymphoma has not been established. The diagnosis/treatment of inflammatory myopathy usually precedes the detection/diagnosis of lymphoma. Immune system dysregulation presumably underlies the evolution of lymphoma in patients with inflammatory myopathies. Inflammatory activity with chronic B-cell activation and/or antigen stimulation is deemed the major risk factor for lymphoma in patients with autoimmunity. A "paraneoplastic" phenomenon or the effects of immunosuppressive therapy may be alternative immune-based mechanisms. In chronic lymphocytic leukemia immune system disturbance rarely results in non-hematological autoimmune disease, including inflammatory myopathies.

Adult and juvenile dermatomyositis: are the distinct clinical features explained by our current understanding of serological subgroups and pathogenic mechanisms?

Adult and juvenile dermatomyositis share the hallmark features of pathognomic skin rash and muscle inflammation, but are heterogeneous disorders with a range of additional disease features and complications. The frequency of important clinical features such as calcinosis, interstitial lung disease and malignancy varies markedly between adult and juvenile disease. These differences may reflect different disease triggers between children and adults, but whilst various viral and other environmental triggers have been implicated, results are so far conflicting. Myositis-specific autoantibodies can be detected in both adults and children with idiopathic inflammatory myopathies. They are associated with specific disease phenotypes and complications, and divide patients into clinically homogenous subgroups. Interestingly, whilst the same autoantibodies are found in both adults and children, the disease features remain different within autoantibody subgroups, particularly with regard to life-threatening disease associations, such as malignancy and rapidly progressive interstitial lung disease. Our understanding of the mechanisms that underlie these differences is limited by a lack of studies directly comparing adults and children. Dermatomyositis is an autoimmune disease, which is believed to develop as a result of an environmental trigger in a genetically predisposed individual. Age-specific host immune responses and muscle physiology may be additional complicating factors that have significant impact on disease presentation. Further study into this area may produce new insights into disease pathogenesis.

[18F]FDG uptake in proximal muscles assessed by PET/CT reflects both global and local muscular inflammation and provides useful information in the management of patients with polymyositis/dermatomyositis

OBJECTIVE

This study aimed to determine whether [(18)F]fluorodeoxyglucose-PET/CT ([(18)F]FDG-PET/CT) discriminates PM/DM from non-muscular diseases and also whether FDG uptake in proximal muscles reflects the activity and severity of muscular inflammation in PM/DM.

METHODS

Twenty treatment-naïve PM/DM patients who underwent [(18)F]FDG-PET/CT were retrospectively identified by reviewing medical records. The same number of age- and sex-matched control patients with non-muscular diseases were also identified. Standardized uptake value (SUV) was calculated for each of the seven proximal muscles. For patient-based assessment, mean proximal muscle SUV was calculated by averaging the SUVs for these proximal muscles bilaterally.

RESULTS

Mean proximal muscle SUVs were significantly greater in PM/DM patients than in control patients (median 1.05 vs 0.69, P < 0.001). Mean proximal muscle SUVs significantly correlated with mean proximal manual muscle test scores (ρ = 0.49, P = 0.028) and serum levels of creatine kinase (ρ = 0.54, P = 0.015) and aldolase (ρ = 0.64, P = 0.002). Furthermore, SUVs in proximal muscles from which biopsy specimens were obtained significantly correlated with histological grade for inflammatory cell infiltration (ρ = 0.66, P = 0.002).

CONCLUSION

Our results suggest that [(18)F]FDG-PET/CT is useful in the diagnosis of PM/DM when inflammation in proximal muscles is globally assessed with quantitative measurements. Our results also indicate that local FDG uptake in a proximal muscle reflects the activity of inflammation in the same muscle and provides useful information in determining the region for muscle biopsy.

Idiopathic inflammatory myopathies: current trends in pathogenesis, clinical features, and up-to-date treatment recommendations

Recently, there have been important advances in the understanding of the pathophysiologic features, assessment, and management of patients with a newly diagnosed idiopathic inflammatory myopathy (IIM). Myositis-specific autoantibodies have been identified to define patient subgroups and offer prognostic implications. Similarly, proinflammatory cytokines, such as interleukin 6 and type 1 interferon-dependent genes, may serve as potential biomarkers of disease activity in adult and juvenile patients with dermatomyositis (DM). Moreover, magnetic resonance imaging has become an important modality for the assessment of muscle inflammation in adult IIM and juvenile DM. Immune-mediated necrotizing myopathies also are being recognized as a subset of IIM triggered by medications such as statins. However, confusion exists regarding effective management strategies for patients with IIM because of the lack of large-scale, randomized, controlled studies. This review focuses primarily on our current management and treatment algorithms for IIM including the care of pediatric patients with juvenile DM. For this review, we conducted a search of PubMed and MEDLINE for articles published from January 1, 1970, to December 1, 2011, using the following search terms: idiopathic inflammatory myopathies, dermatomyositis, polymyositis, juvenile dermatomyositis, sporadic inclusion body myositis, inclusion body myositis, inflammatory myositis, myositis, myopathies, pathogenesis, therapy, and treatment. Studies published in English were selected for inclusion in our review as well as additional articles identified from bibliographies.

Juvenile dermatomyositis

Juvenile dermatomyositis (JDM) is a systemic, inflammatory, idiopathic disease, mainly affecting the skin and the muscles, starting before the age of 16, with an incidence around one case per 1 million children. Some patients display typical features of JDM without skin involvement, or even without muscle involvement; however, both tissues are affected over time in most cases. Diagnosis criteria were established by Bohan and Peter 35 years ago, based on the presence of typical skin rash and proximal muscle involvement. Other conditions have to be ruled out before making a diagnosis of JDM, such as other connective tissue diseases, polymyositis, infectious/postinfectious myositis, genetic diseases, or metabolic or drug-induced myopathies. Unlike adult-onset dermatomyositis, JDM is exceptionally associated with a malignant disease. JDM may also affect several organs, including the lungs and the digestive tract. In a subset of patients, glucose intolerance, lipodystrophia and/or calcinosis develop. Delay in treatment initiation or inadequate treatment may favor diffuse, debilitating calcinosis. JDM patients have to be referred to reference pediatric centers to properly assess disease activity and disease-related damage (including low bone density in most cases), and to define the best treatment. Long-lasting corticosteroid therapy remains the gold standard, together with physiotherapy. Ongoing clinical trials are assessing the effect of several immunosuppressive and immunomodulatory drugs, which may help to control the disease and possibly demonstrate a corticosteroid-sparing effect. Most patients respond to treatment; relapses are frequent but a complete disease remission is achieved in most cases before adulthood.

Is juvenile dermatomyositis a different disease in children up to three years of age at onset than in children above three years at onset? A retrospective review of 23 years of a single center's experience

BACKGROUND

We tested the hypothesis that the course and outcome of juvenile dermatomyositis (JDM) in children seen at one center with the JDM disease onset at or below three years of age is different from that in the children with disease onset at greater than three years of age.

METHODS

Institutional Review Board approval was obtained to retrospectively review the charts of 78 patients from age 0-18 years with JDM seen in the pediatric rheumatology clinic at Nationwide Children's Hospital in Columbus, Ohio over the past 23 years from January 1988. The diagnosis was made by the treating pediatric rheumatologist. Not all the patients met the Bohan and Peter criteria, as muscle biopsy and EMG were not always performed and we utilized a modified JDM criteria. The data regarding disease course and outcome were collected as of the last clinic follow-up or to July 1, 2010. We used the Wilcoxon Two-Sample test to compare numerical variables between two age groups, and used logistic regression to compare categorical variables between two age groups in SAS 9.1.3. Minitab-16 was used to calculate various mean, median, modes, standard deviations and range. For survival analysis, we used Kaplan-Meier method with log-rank test.

RESULTS

The mean age of onset in the two groups at Nationwide Children's Hospital was 27 months and 91 months. The mean times between onset of symptoms to diagnosis in the younger and older age groups was 5.6 months and 4.5 months, respectively, not a statistically significant difference. The younger onset group had more females (p=0.05) and their disease onset occurred less frequently during the typical winter-spring seasons (p=0.031). The younger onset group was more likely to have a preceding fever (p=0.029) and family history of autoimmune diseases (p=0.012). The younger onset group was less likely to have heliotrope rash (p=0.04), Gottron's sign (p=0.049), capillary loop abnormalities (p=0.010), or elevations in creatine kinase (CK, p=0.022), aspartate aminotransferase (AST, p=0.021) or aldolase (p=0.035). The younger onset group was treated less often with pulse methylprednisolone at diagnosis (p=0.043) and less often with hydroxychloroquine (p=0.035). There were no differences between the two groups regarding initial oral steroid dose (p=0.8017), number of patients who received methotrexate at diagnosis (p=0.709), and the number who ever received other immunosuppressants (p=0.323). The mean and maximum duration (mean duration 24.3 months vs. 35.2 months, maximum duration 51 vs. 124 months in younger and older onset group respectively) of methotrexate therapy, and the mean and maximum duration of oral steroid therapy (Mean duration 16.8 months vs. 33.3 months, maximum duration 50 vs. 151 months in younger and older onset group respectively), was shorter in the younger group. The younger onset patients were less likely to have active disease at 5 years (9% vs. 35.7%, p=0.015) and 10 years post-diagnosis (9% vs. 45.1%, p=0.011, Table 7). The younger patients were less likely to have osteonecrosis (p=0.023). Two disease-related deaths occurred in the younger group, none in the older group. The results of the survival analysis showed that the difference between the age groups was statistically significant (p < 0.012). The sex and race were not significant (p> 0.26 and p>0.95, respectively).

CONCLUSIONS

There were significant differences between JDM patients with disease onset at or below age three years at our center, compared to their older counterparts. Younger patients in our cohort had fewer typical findings at diagnosis and a milder disease course without needing as long a duration of corticosteroids and immunosuppression. Patients with a younger onset had a higher mortality rate but mortalities were unusual and numbers small. The younger group had a similar complication rate compared to the older onset patients, except for osteonecrosis which was higher in the older onset group. These findings differ from the previous reports that a younger age of onset in JDM is often associated with a more severe disease, as results at our center suggest that children with younger onset JDM appear to be atypical but may do well compared to the older JDM patients.

Immunoglobulin gene polymorphisms are susceptibility factors in clinical and autoantibody subgroups of the idiopathic inflammatory myopathies

OBJECTIVE

To investigate possible associations of GM and KM markers with adult and juvenile forms of the idiopathic inflammatory myopathies (IIMs) in Caucasian and African American patients.

METHODS

We performed serologic analyses of polymorphic determinants associated with immunoglobulin gamma heavy chains (GM) and kappa light chains (KM) in large populations of Caucasian patients (n= 514 [297 adults and 217 children]) and African American patients (n=123 [73 adults and 50 children]) with IIM representing the major clinical and autoantibody groups.

RESULTS

For Caucasian patients with dermatomyositis (DM), the Gm 3 23 5,13 phenotype was a risk factor in both adults (odds ratio [OR] 2.2, corrected P [Pcorr]=0.020) and children (OR 2.2, Pcorr=0.0013). Of interest, the GM 13 allotype was a risk factor for juvenile DM in both Caucasian subjects (OR 3.9, Pcorr<0.0001) and African American subjects (OR 4.8, Pcorr=0.033). However, the Gm 1,3,17 5,13,21 phenotype was a risk factor for juvenile DM in Caucasian subjects but not African American subjects. Among the IIM autoantibody groups, Gm 3 23 5,13 was a risk factor in Caucasian adults with anti-Jo-1 autoantibodies (OR 3.4, Pcorr=0.0031), while the GM 3 allotype was protective in adults with anti-threonyl-transfer RNA synthetase or anti-U RNP autoantibodies (OR 0.1, Pcorr=0.047 and OR 0.2, Pcorr=0.034, respectively). In contrast, GM 6 was a risk factor in African American adults with anti-signal recognition particle autoantibodies (OR 7.5, Pcorr=0.041).

CONCLUSION

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

Juvenile dermatomyositis and other idiopathic inflammatory myopathies of childhood

Juvenile dermatomyositis, the most common inflammatory myopathy of childhood, is a rare systemic autoimmune vasculopathy that is characterised by weakness in proximal muscles and pathognomonic skin rashes. The length of time before the initiation of treatment affects presenting symptoms, laboratory measures, and pathophysiology. It also affects disease outcomes, including the development of pathological calcifications, which are associated with increased morbidity. Both genetic and environmental risk factors seem to have a role in the cause of juvenile dermatomyositis; HLA B8-DRB1*0301 ancestral haplotype is a strong immunogenetic risk factor, and antecedent infections and birth seasonality suggest that environmental stimuli might increase risk. Activation of dendritic cells with upregulation of genes induced by type-1 interferon (alpha) in muscle and peripheral blood seems to be central to disease pathogenesis. Treatment often includes combinations of corticosteroids, methotrexate, and other immunosuppressive agents. Disease outcome, if treatment is initiated early, is generally good. Randomised controlled trials are needed to define the most effective treatments.

Focal preauricular dermal dysplasia: report of two cases and a review of literature

We report two cases of focal preauricular dermal dysplasia and review the available literature. Focal preauricular dermal dysplasia is a form of aplasia cutis congenita in which atrophic skin lesions occur in a stereotypical bilateral distribution in the preauricular region. Although focal preauricular dermal dysplasia and membranous cutis aplasia of the scalp share clinical similarities, focal preauricular dermal dysplasia represents a form of aplasia cutis congenita that is not typically associated with extracutaneous anomalies.

Dermatomyositis

Dermatomyositis (DM) is a chronic inflammatory disorder of the skin and muscles. Although thought to be autoimmune in origin, many questions remain as to the etiopathogenesis of this disease. DM has classically been considered a humorally mediated disease. Current evidence, however, seems to increasingly support alternative (though not mutually exclusive) mechanisms of pathogenesis, including cell-mediated and innate immune system dysfunction. Pathologic findings of DM in muscle include infarcts, perifascicular atrophy, endothelial cell swelling and necrosis, vessel wall membrane attack complex deposition, and myocyte-specific MHC I upregulation. As for the skin, histopathologic findings include hyperkeratosis, epidermal basal cell vacuolar degeneration and apoptosis, increased dermal mucin deposition, and a cell-poor interface dermatitis. Autoantibodies, particularly those that bind nuclear or cytoplasmic ribonucleoprotein antigens, are also commonly found in DM, although their importance in pathogenesis remains unclear. Defective cellular clearance, genetic predilection and environmental exposures, such as viral infection, may also play an important role in the pathogenesis of DM. The seminal work regarding the pathogenesis of DM is reviewed and an update on the recent basic and molecular advances in the field is provided.

[New classifications and pathophysiology of the inflammatory myopathies]

SCOPE

Review on new classifications of myositis linked with their different pathophysiology.

CURRENT SITUATION AND SALIENT POINTS

The classification of myositis refined recently, taking into account clinical (such as isolated muscle involvement or not, association with cancer...), immunological (presence or absence of auto-antibodies) and pathological criteria. This new classification has the ability to separate different clinical and physiopathological entities, having actually different prognosis factors. The most common inflammatory myopathies include dermatomyositis (DM), polymyositis (PM), inclusion body myositis (IBM), but also, overlap myositis (defined, among others, by the presence of auto-antibodies), and myositis associated to cancers. These myopathies may be also distinguished by their histological features which also reflect their different underlying pathogeneses. The mechanism of DM is complement-mediated microangiopathy, the inflammatory infiltrate being secondary to ischaemic damage. In PM the muscle fibres are damaged by cytotoxic CD8 T lymphocytes. IBM may be a degenerative disease with accumulation of a variety of proteins within the fibres. The inflammatory infiltrate, which is similar to that seen in PM, may be secondary to accumulated proteins.

PERSPECTIVES

These diseases with different pathogeny and prognosis should be treated by specific approaches. That is the reason why we initiated specific clinical trials for respectively inclusion body myositis and overlap myositis.

Immunogenetic risk and protective factors for juvenile dermatomyositis in Caucasians

OBJECTIVE

To define the relative importance (RI) of class II major histocompatibility complex (MHC) alleles and peptide binding motifs as risk or protective factors for juvenile dermatomyositis (DM), and to compare these with HLA associations in adult DM.

METHODS

DRB1 and DQA1 typing was performed in 142 Caucasian patients with juvenile DM, and the results were compared with HLA typing data from 193 patients with adult DM and 797 race-matched controls. Random Forests classification and multiple logistic regression were used to assess the RI of the HLA associations.

RESULTS

The HLA-DRB1*0301 allele was a primary risk factor (odds ratio [OR] 3.9), while DQA1*0301 (OR 2.8), DQA1*0501 (OR 2.1), and homozygosity for DQA1*0501 (OR 3.2) were additional risk factors for juvenile DM. These risk factors were not present in patients with adult DM without defined autoantibodies. DQA1 alleles *0201 (OR 0.37), *0101 (OR 0.38), and *0102 (OR 0.51) were identified as novel protective factors for juvenile DM, the latter 2 also being protective factors in adult DM. The peptide binding motif DRB1 (9)EYSTS(13) was a risk factor, and DQA1 motifs F(25), S(26), and (45)(V/A)W(R/K)(47) were protective. Random Forests classification analysis revealed that among the identified risk factors for juvenile DM, DRB1*0301 had a higher RI (100%) than DQA1*0301 (RI 57%), DQA1*0501 (RI 42%), or the peptide binding motifs. In a logistic regression model, DRB1*0301 and DQA1*0201 were the strongest risk and protective factors, respectively, for juvenile DM.

CONCLUSION

DRB1*0301 is ranked higher in RI than DQA1*0501 as a risk factor for juvenile DM. DQA1*0301 is a newly identified HLA risk factor for juvenile DM, while 3 of the DQA1 alleles studied are newly identified protective factors for juvenile DM.

HLA polymorphisms in African Americans with idiopathic inflammatory myopathy: allelic profiles distinguish patients with different clinical phenotypes and myositis autoantibodies

OBJECTIVE

To investigate possible associations of HLA polymorphisms with idiopathic inflammatory myopathy (IIM) in African Americans, and to compare this with HLA associations in European American IIM patients with IIM.

METHODS

Molecular genetic analyses of HLA-A, B, Cw, DRB1, and DQA1 polymorphisms were performed in a large population of African American patients with IIM (n = 262) in whom the major clinical and autoantibody subgroups were represented. These data were compared with similar information previously obtained from European American patients with IIM (n = 571).

RESULTS

In contrast to European American patients with IIM, African American patients with IIM, in particular those with polymyositis, had no strong disease associations with HLA alleles of the 8.1 ancestral haplotype; however, African Americans with dermatomyositis or with anti-Jo-1 autoantibodies shared the risk factor HLA-DRB1*0301 with European Americans. We detected novel HLA risk factors in African American patients with myositis overlap (DRB1*08) and in African American patients producing anti-signal recognition particle (DQA1*0102) and anti-Mi-2 autoantibodies (DRB1*0302). DRB1*0302 and the European American-, anti-Mi-2-associated risk factor DRB1*0701 were found to share a 4-amino-acid sequence motif, which was predicted by comparative homology analyses to have identical 3-dimensional orientations within the peptide-binding groove.

CONCLUSION

These data demonstrate that North American IIM patients from different ethnic groups have both shared and distinct immunogenetic susceptibility factors, depending on the clinical phenotype. These findings, obtained from the largest cohort of North American minority patients with IIM studied to date, add additional support to the hypothesis that the myositis syndromes comprise multiple, distinct disease entities, perhaps arising from divergent pathogenic mechanisms and/or different gene-environment interactions.

The heterogeneity of juvenile myositis

Juvenile myositis is a heterogeneous group of systemic autoimmune diseases, in which clinical and serologic subgroups result in subsets of patients with distinct clinical manifestations, disease courses, immunogenetic associations, responses to therapy, and prognoses. A newly identified autoantibody of unknown specificity, anti-p155, is myositis-associated and seen in up to 20-30% of juvenile and adult DM patients. HLA DRB1*0301 and its linked allele DQA1*0501 have been identified as the major immunogenetic risk factor for juvenile and adult DM in both European- and African-American patients, and DQA1*0301 is an additional risk factor in European-American patients. Several DQA1 alleles also are protective for juvenile DM. Environmental risk factors are poorly understood, but growing evidence suggests a role for infectious agents and ultraviolet radiation. The current therapy of juvenile DM consists of corticosteroids and other immunosuppressive agents, with the adjunctive treatment of cutaneous manifestations and rehabilitation. Therapeutic trials of biologic agents, including anti-TNFalpha and anti-CD20, may aid in developing promising new therapies for these disorders.

Unusually high frequency of autoantibodies to PL-7 associated with milder muscle disease in Japanese patients with polymyositis/dermatomyositis

OBJECTIVE

Autoantibodies to aminoacyl transfer RNA synthetases, such as histidyl (Jo-1), threonyl (PL-7), alanyl (PL-12), glycyl (EJ), and isoleucyl (OJ), are closely associated with a subset of patients with polymyositis/dermatomyositis (PM/DM) complicated by interstitial lung disease (ILD). Anti-Jo-1 is by far the most common, found in 15-25% of patients with PM/DM, whereas the other types are found in only approximately 3% of these patients. In this study, the clinical associations of these autoantibodies in Japanese patients with PM/DM were investigated.

METHODS

The diagnoses of PM/DM and amyopathic DM (ADM) were based on the Bohan and Peter criteria and Sontheimer's definition, respectively. Sera from 36 Japanese patients with PM/DM (13 with PM, 20 with DM, 3 with ADM) were screened by immunoprecipitation and by enzyme-linked immunosorbent assay (for Jo-1). Clinical and laboratory data were collected.

RESULTS

The frequencies of autoantibodies to Jo-1 (22%) and to EJ, OJ, and PL-12 (3-6%) were similar to those found in previous studies, including studies of Japanese subjects. However, anti-PL-7 was found in 17% of patients, in contrast to a frequency of 1-4% in previous studies (P < 0.02-0.0002). The 6 anti-PL-7-positive patients were not related, and no skewing in year or month of disease development, place of residence or work, or occupation was found. All patients had ILD, consistent with the clinical features of antisynthetase-positive patients. The patients with anti-PL-7 had lower serum muscle enzyme levels and milder muscle weakness (P < 0.05) compared with anti-Jo-1-positive patients.

CONCLUSION

Anti-PL-7 was found at an unusually high frequency in this group of Japanese patients with myositis. Although anti-PL-7, similar to anti-Jo-1, is associated with PM/DM with ILD, muscle involvement in the patients with anti-PL-7 appeared to be milder than that in the anti-Jo-1 subset.

Immunogenetic risk and protective factors for the idiopathic inflammatory myopathies: distinct HLA-A, -B, -Cw, -DRB1, and -DQA1 allelic profiles distinguish European American patients with different myositis autoantibodies

The idiopathic inflammatory myopathies (IIM) are systemic connective tissue diseases defined by chronic muscle inflammation and weakness associated with autoimmunity. We have performed low to high resolution molecular typing to assess the genetic variability of major histocompatibility complex loci (HLA-A, -B, -Cw, -DRB1, and -DQA1) in a large population of European American patients with IIM (n = 571) representing the major myositis autoantibody groups. We established that alleles of the 8.1 ancestral haplotype (8.1 AH) are important risk factors for the development of IIM in patients producing anti-synthetase/anti-Jo-1, -La, -PM/Scl, and -Ro autoantibodies. Moreover, a random forests classification analysis suggested that 8.1 AH-associated alleles B*0801 and DRB1*0301 are the principal HLA risk markers. In addition, we have identified several novel HLA susceptibility factors associated distinctively with particular myositis-specific (MSA) and myositis-associated autoantibody (MAA) groups of the IIM. IIM patients with anti-PL-7 (anti-threonyl-tRNA synthetase) autoantibodies have a unique HLA Class I risk allele, Cw*0304 (pcorr = 0.046), and lack the 8.1 AH markers associated with other anti-synthetase autoantibodies (for example, anti-Jo-1 and anti-PL-12). In addition, HLA-B*5001 and DQA1*0104 are novel potential risk factors among anti-signal recognition particle autoantibody-positive IIM patients (pcorr = 0.024 and p = 0.010, respectively). Among those patients with MAA, HLA DRB1*11 and DQA1*06 alleles were identified as risk factors for myositis patients with anti-Ku (pcorr = 0.041) and anti-La (pcorr = 0.023) autoantibodies, respectively. Amino acid sequence analysis of the HLA DRB1 third hypervariable region identified a consensus motif, 70D (hydrophilic)/71R (basic)/74A (hydrophobic), conferring protection among patients producing anti-synthetase/anti-Jo-1 and -PM/Scl autoantibodies. Together, these data demonstrate that HLA signatures, comprising both risk and protective alleles or motifs, distinguish IIM patients with different myositis autoantibodies and may have diagnostic and pathogenic implications. Variations in associated polymorphisms for these immune response genes may reflect divergent pathogenic mechanisms and/or responses to unique environmental triggers in different groups of subjects resulting in the heterogeneous syndromes of the IIM.

Immunogenetic risk and protective factors for the idiopathic inflammatory myopathies: distinct HLA-A, -B, -Cw, -DRB1 and -DQA1 allelic profiles and motifs define clinicopathologic groups in caucasians

The idiopathic inflammatory myopathies (IIM) are systemic connective tissue diseases in which autoimmune pathology is suspected to promote chronic muscle inflammation and weakness. We have performed low to high resolution genotyping to characterize the allelic profiles of HLA-A, -B, -Cw, -DRB1, and -DQA1 loci in a large population of North American Caucasian patients with IIM representing the major clinicopathologic groups (n = 571). We confirmed that alleles of the 8.1 ancestral haplotype were important risk markers for the development of IIM, and a random forests classification analysis suggested that within this haplotype, HLA-B*0801, DRB1*0301 and/ or closely linked genes are the principal HLA risk factors. In addition, we identified several novel HLA factors associated distinctly with 1 or more clinicopathologic groups of IIM. The DQA1*0201 allele and associated peptide-binding motif (KLPLFHRL) were exclusive protective factors for the CD8+ T cell-mediated IIM forms of polymyositis (PM) and inclusion body myositis (IBM) (pc < 0.005). In contrast, HLA-A*68 alleles were significant risk factors for dermatomyositis (DM) (pc = 0.0021), a distinct clinical group thought to involve a humorally mediated immunopathology. While the DQA1*0301 allele was detected as a possible risk factor for IIM, PM, and DM patients (p < 0.05), DQA1*03 alleles were protective factors for IBM (pc = 0.0002). Myositis associated with malignancies was the most distinctive group of IIM wherein HLA Class I alleles were the only identifiable susceptibility factors and a shared HLA-Cw peptide-binding motif (AGSHTLQWM) conferred significant risk (pc = 0.019). Together, these data suggest that HLA susceptibility markers distinguish different myositis phenotypes with divergent pathogenetic mechanisms. These variations in associated HLA polymorphisms may reflect responses to unique environmental triggers resulting in the tissue pathospecificity and distinct clinicopathologic syndromes of the IIM.

Life-threatening dermatoses due to connective tissue disorders

Connective tissue disorders such as scleroderma, dermatomyositis and lupus erythematosus are autoimmune, multi-system disorders whose clinical manifestations can be restricted to the skin or may involve many organs. The degree and rate of organ system involvement defer, as does the prognosis and rapidity of disease progression. In this article, scleroderma, dermatomyositis and lupus erythematosus will be reviewed in respect to their life-threatening potential.

Rituximab in the treatment of dermatomyositis: An open-label pilot study

OBJECTIVE

To test the hypothesis that B cells play a role in the pathophysiology of dermatomyositis (DM) by examining the effect of B cell depletion in patients with symptomatic DM. Patients were treated with rituximab, a CD20+ B cell-depleting monoclonal antibody.

METHODS

This was an open-label uncontrolled pilot trial in 7 adult patients with DM, 6 of whom had longstanding illness that was responding inadequately to a number of currently available immunosuppressive agents. All patients received 4 intravenous infusions of rituximab given at weekly intervals. Patients were followed up for up to 1 year without further treatment with rituximab. One patient was lost to followup. The principal efficacy outcome was muscle strength, measured by quantitative dynomometry.

RESULTS

All 6 evaluable patients exhibited major clinical improvement, with muscle strength increasing over baseline by 36-113%. Maximal improvements in muscle strength occurred as early as 12 weeks after the initial infusion of rituximab. CD20+ B cells were effectively depleted in all patients by 12 weeks. Four patients experienced a return of symptoms that coincided with the return of B cells before the 52-week end point. Two patients maintained their increased muscle strength at 52 weeks, and 1 of these patients maintained this strength even after the return of B cells. Other symptoms of DM, including rash, alopecia, and reduced forced vital capacity, improved markedly in patients with these symptoms. Rituximab was well tolerated, with no treatment-related severe or serious adverse events during the observation period of this study.

CONCLUSION

This small open-label study of DM patients treated with rituximab provided sufficiently encouraging results to justify a more formal evaluation of the value of B cell depletion therapy in the treatment of DM.

Seasonal influence on the onset of idiopathic inflammatory myopathies in serologically defined groups

OBJECTIVE

To assess possible seasonal patterns in the onset of polymyositis (PM) and dermatomyositis (DM).

METHODS

The study group comprised 503 patients who met the criteria for probable or definite PM or DM and for whom detailed data on the time of myositis onset were available. Statistical analyses were performed using a Poisson model that assessed associations of ethnicity, sex, autoantibody presence, and month of onset of muscle weakness.

RESULTS

There were no significant seasonal patterns of disease onset in myositis patients as a whole or in the total PM or DM populations. Significant seasonal associations were present, however, in the serologically defined groups. In the 131 patients with antisynthetase autoantibodies who were categorized as non-black, myositis onset peaked in March-April (P = 0.03). Among the antisynthetase-positive patients, the association was predominantly in those with PM (n = 85; P = 0.05) and in men (n = 51; P = 0.042). Patients with anti-signal recognition particle autoantibodies, however, did not have a significant seasonal onset, which is in contrast to previous findings. Patients without myositis-specific autoantibodies showed a significant peak in summer, with myositis onset in June-July (n = 252; P = 0.03); this seasonal association was significant in women (n = 182; P = 0.005), whereas there was no seasonal pattern in men (P = 0.9).

CONCLUSION

These findings, in conjunction with other data, suggest that diverse environmental agents, acting upon different immunogenetic backgrounds, result in distinct immune responses and clinical syndromes in the idiopathic inflammatory myopathies. Our results emphasize the importance of considering more homogeneous disease groups, based on clinicopathologic features, immune responses, ethnicity, and sex, when attempting to decipher the pathogeneses of autoimmune disorders.

Polymyositis and dermatomyositis

The inflammatory myopathies, commonly described as idiopathic, are the largest group of acquired and potentially treatable myopathies. On the basis of unique clinical, histopathological, immunological, and demographic features, they can be differentiated into three major and distinct subsets: dermatomyositis, polymyositis, and inclusion-body myositis. Use of new diagnostic criteria is essential to discriminate between them and to exclude other disorders. Dermatomyositis is a microangiopathy affecting skin and muscle; activation and deposition of complement causes lysis of endomysial capillaries and muscle ischaemia. In polymyositis and inclusion-body myositis, clonally expanded CD8-positive cytotoxic T cells invade muscle fibres that express MHC class I antigens, which leads to fibre necrosis via the perforin pathway. In inclusion-body myositis, vacuolar formation with amyloid deposits coexists with the immunological features. The causative autoantigen has not yet been identified. Upregulated vascular-cell adhesion molecule, intercellular adhesion molecule, chemokines, and their receptors promote T-cell transgression, and various cytokines increase the immunopathological process. Early initiation of therapy is essential, since both polymyositis and dermatomyositis respond to immunotherapeutic agents. New immunomodulatory agents currently being tested in controlled trials may prove promising for difficult cases.