The clinico-serological spectrum of overlap myositis

Clinicopathological Reclassification of Idiopathic Inflammatory Myopathy to Match the Serological Results of Myositis-Specific Antibodies

BACKGROUND AND PURPOSE

Advances in serological tests are transforming the classification of idiopathic inflammatory myopathy (IIM). The new criteria suggested by the 119th European Neuromuscular Center international workshop divide IIM cases into four main diseases according to clinical and pathological findings, adding immune-mediated necrotizing myositis and nonspecific myositis to the classic categories of polymyositis and dermatomyositis.

METHODS

Seventy one cases of IIM with sufficient available clinical and pathological data were reviewed to be reclassified according to the new criteria.

RESULTS

Most of the cases previously classified as polymyositis (77.8%, 35/45) were reclassified as immune-mediated necrotizing myopathy. The results of myositis-specific antibodies matched well with the new clinicopathological classification.

CONCLUSIONS

This new clinicopathological classification for IIM in combination with serological test results could be applied to our previous case series. Adoption of the new criteria will lead to a better understanding of the disease and hence new therapeutic insights.

Detection of Myositis Autoantibodies by Multi-Analytic Immunoassays in a Large Multicenter Cohort of Patients with Definite Idiopathic Inflammatory Myopathies

BACKGROUND

The usefulness of myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs) for the assessment of idiopathic inflammatory myopathies (IIMs) is acknowledged, but laboratory standardization remains a challenge. We detected MSAs/MAAs by multi-analytic line immunoassay (LIA) and particle-based multi-analyte technology (PMAT) in a multicenter cohort of patients with IIMs.

METHODS

We tested the sera from 411 patients affected with definite IIM, including 142 polymyositis (PM), 147 dermatomyositis (DM), 19 cancer-associated myositis, and 103 overlap myositis syndrome (OM), and from 269 controls. MSAs/MAAs were determined by 16Ags LIA in all sera, and anti-HMGCR by ELISA in 157/411 IIM sera and 91/269 control sera. The analytical specificity of LIA/HMGCR ELISA was compared with that of PMAT in 89 MSA+ IIM sera.

RESULTS

MSAs/MAAs were positive in 307/411 (75%) IIM patients and 65/269 (24%) controls by LIA (Odds Ratio 9.26, 95% CI 6.43-13.13, p < 0.0001). The sensitivity/specificity of individual MSAs/MAAs were: 20%/100% (Jo-1), 3%/99.3% (PL-7), 4%/98.8% (PL-12), 1%/100% (EJ), 0.7%/100% (OJ), 9%/98% (SRP), 5.6%/99.6% (TIF1γ), 4.6%/99.6% (MDA5), 8%/96% (Mi-2), 1.5%/98% (NXP2), 1.7%/100% (SAE1), 4%/92% (Ku), 8.5%/99% (PM/Scl-100), 8%/96% (PM/Scl-75), and 25.5%/79% (Ro52). Anti-HMGCR was found in 8/157 (5%) IIM patients and 0/176 (0%) controls by ELISA (p = 0.007). Concordance between LIA/HMGCR ELISA and PMAT was found in 78/89 (88%) samples. Individual MSAs detected by LIA were associated with IIM subsets: Jo-1 with PM and OM, PL-12 with OM, Mi-2, TIF1γ, and MDA5 with DM, SRP with PM, and PM/Scl-75/100 with OM (p < 0.001 for all).

CONCLUSIONS

Since MSAs are mostly mutually exclusive, multi-specific antibody profiling seems effective for a targeted clinical-serologic approach to the diagnosis of IIMs.

The Involvement of Smooth Muscle, Striated Muscle, and the Myocardium in Scleroderma: A Review

Systemic sclerosis (SSc) is a complex autoimmune disease characterized by heterogeneous changes involving numerous organs and systems. The currently available data indicate that muscle injury (both smooth and striated muscles) is widespread and leads to significant morbidity, either directly or indirectly. From the consequences of smooth muscle involvement in the tunica media of blood vessels or at the level of the digestive tract, to skeletal myopathy (which may be interpreted strictly in the context of SSc, or as an overlap with idiopathic inflammatory myopathies), muscular injury in scleroderma translates to a number of notable clinical manifestations. Heart involvement in SSc is heterogenous depending on the definition used in the various studies. The majority of SSc patients experience a silent form of cardiac disease. The present review summarizes certain important features of myocardial, as well as smooth and skeletal muscle involvement in SSc. Further research is needed to fully describe and understand the pathogenic pathways and the implications of muscle involvement in scleroderma.

Pathophysiological Mechanisms and Treatment of Dermatomyositis and Immune Mediated Necrotizing Myopathies: A Focused Review

Idiopathic inflammatory myopathies (IIM), collectively known as myositis, are a composite group of rare autoimmune diseases affecting mostly skeletal muscle, although other organs or tissues may also be involved. The main clinical feature of myositis is subacute, progressive, symmetrical muscle weakness in the proximal arms and legs, whereas subtypes of myositis may also present with extramuscular features, such as skin involvement, arthritis or interstitial lung disease (ILD). Established subgroups of IIM include dermatomyositis (DM), immune-mediated necrotizing myopathy (IMNM), anti-synthetase syndrome (ASyS), overlap myositis (OM) and inclusion body myositis (IBM). Although these subgroups have overlapping clinical features, the widespread variation in the clinical manifestations of IIM suggests different pathophysiological mechanisms. Various components of the immune system are known to be important immunopathogenic pathways in IIM, although the exact pathophysiological mechanisms causing the muscle damage remain unknown. Current treatment, which consists of glucocorticoids and other immunosuppressive or immunomodulating agents, often fails to achieve a sustained beneficial response and is associated with various adverse effects. New therapeutic targets have been identified that may improve outcomes in patients with IIM. A better understanding of the overlapping and diverging pathophysiological mechanisms of the major subgroups of myositis is needed to optimize treatment. The aim of this review is to report on recent advancements regarding DM and IMNM.

Morphological Characteristics of Idiopathic Inflammatory Myopathies in Juvenile Patients

Background: In juvenile idiopathic inflammatory myopathies (IIMs), morphological characteristic features of distinct subgroups are not well defined. New treatment strategies require a precise diagnosis of the subgroups in IIM, and, therefore, knowledge about the pathomorphology of juvenile IIMs is warranted. Methods: Muscle biopsies from 15 patients (median age 8 (range 3–17) years, 73% female) with IIM and seven controls were analyzed by standard methods, immunohistochemistry, and transmission electron microscopy (TEM). Detailed clinical and laboratory data were accessed retrospectively. Results: Proximal muscle weakness and skin symptoms were the main clinical symptoms. Dermatomyositis (DM) was diagnosed in 9/15, antisynthetase syndrome (ASyS) in 4/15, and overlap myositis (OM) in 2/15. Analysis of skeletal muscle tissues showed inflammatory cells and diffuse upregulation of MHC class I in all subtypes. Morphological key findings were COX-deficient fibers as a striking pathology in DM and perimysial alkaline phosphatase positivity in anti-Jo-1-ASyS. Vascular staining of the type 1 IFN-surrogate marker, MxA, correlated with endothelial tubuloreticular inclusions in both groups. None of these specific morphological findings were present in anti-PL7-ASyS or OM patients. Conclusions: Morphological characteristics discriminate IIM subtypes in juvenile patients, emphasizing differences in aetiopathogenesis and supporting the notion of individual and targeted therapeutic strategies.

Association between clinical phenotypes of dermatomyositis and polymyositis with myositis-specific antibodies and overlap systemic autoimmune diseases

The aim of this study was to evaluate the association between clinical phenotypes of dermatomyositis (DM) and polymyositis (PM) with myositis-specific antibodies (MSAs), and overlap diagnosis of systemic autoimmune diseases.This cross-sectional study was conducted on 67 patients with DM and 27 patients with PM recruited from a regional hospital in southern Taiwan. Clinical phenotypes of DM and PM were assessed and MSAs were measured using a commercial line blot assay. The association of clinical phenotypes of DM and PM with MSAs and overlap diagnosis of systemic autoimmune diseases was performed using univariate and multiple logistic regression analyses.Clinically, patients with DM and PM and overlap diagnosis of systemic sclerosis were associated with a higher risk of interstitial lung diseases (ILDs) (odds ratio [OR] = 6.73; P = .048), Raynaud phenomenon (OR = 7.30; P = .034), and malignancy (OR = 350.77; P = .013). The risk of malignancy was also associated with older age (OR 1.31; P = .012), and male patients were associated with a higher risk of fever. For MSAs, anti-aminoacyl-tRNA synthetase antibodies were associated with ILD, antinuclear antibody were associated with a lower risk of arthritis, anti-transcription intermediary factor 1-gamma antibodies were associated with milder symptoms of muscle weakness, anti-Ku antibodies were associated with overlap diagnosis of systemic lupus erythematosus, and anti-Ro52 antibodies were associated with the development of Raynaud phenomenon and Sjögren syndrome.MSAs and overlap diagnosis of systemic sclerosis were significantly associated with clinical phenotypes of DM and PM. Physicians should be vigilant for malignancy in older DM and PM patients with overlap diagnosis of systeic sclerosis. The possibility of developing ILD in patients with overlap diagnosis of systemic sclerosis or serum positivity of anti-aminoacyl-tRNA synthetase antibodies should be considered.

Peripheral nervous system manifestations of rheumatological diseases

Rheumatological diseases result in immune-mediated injury to not only connective tissue, but often components of the peripheral nervous system. These overlap conditions can be broadly categorized as peripheral neuropathies and overlap myositis. The peripheral neuropathies are distinctive as many have unusual presentations such as non-length-dependent, small fiber neuropathies and sensory neuronopathies (both due to dorsal root ganglia dysfunction), multiple mononeuropathies (e.g. vasculitic neuropathies), and even cranial neuropathies. Overlap myositis is increasingly recognized and is often associated with specific autoantibodies. Sarcoidosis also has widespread neurological manifestations and impacts both the peripheral nerves and muscle. Much work is needed to fully characterize the vast presentations of these overlap diseases. Given the rarity of these disorders, they are understudied, resulting in significant knowledge gaps with regards to their underlying pathophysiology and the best treatment approach. A basic knowledge of these disorders is mandatory for both practicing rheumatologists and neurologists as prompt recognition and early initiation of immunotherapy may prevent significant morbidity and permanent disability.

Characteristics and outcomes of overlap myositis: a comparative multigroup cohort study in adults from the MyoCite cohort

Overlap myositis (OM), an important subset of idiopathic inflammatory myopathies (IIM), is being increasingly recognized with wider myositis-specific autoantibody (MSA) testing. We studied the differences in clinical characteristics and long-term outcomes of OM with Dermatomyositis (DM), Polymyositis (PM), anti-synthetase syndrome (ASSD), and Cancer-associated IIM (CAM). Data from the MyoCite registry (Dec2017-May2020), a prospective dataset of IIM was extracted for the clinical profile, and MSAs, immunosuppressants received, disease activity (relapses and incomplete response), and treatment-related (drugs ADRs and infections) adverse events (DRAE and TRAE) were collected and analyzed between groups. Of 214 adults (58-OM,89-DM,27-ASSD,33-PM,7-CAM), OM had a greater female preponderance (13.5:1). Raynaud's and sclerodactyly were the prime distinguishing features of OM. OM could be distinguished from PM by frequent arthritis (OR-3.2) and infrequent dysphagia (OR-0.17); DM with greater nephritis (OR-20), infrequent dysphagia (OR-0.24) and rashes (OR-0.02); and ASSD by infrequent ILD (OR-0.07), and mechanic's hand (OR-0.05). 50% fulfilled the classification criteria for ASSD in the absence of MSA testing. ANA was positive more often (PM/DM: OR-6.7) and anti-Ro52 (OR-4.5) frequent in OM. Baseline serum creatinine and acute phase reactants were higher. OM received lower glucocorticoids (0 mg/kg, p < 0.001). Overall, 90% and 84% of OM at 12 and 24 months, respectively, achieved remission, with similar DRAE and TRAE as other IIM subsets. OM can be misdiagnosed as ASSD in the absence of MSA testing. Raynaud's, sclerodactyly, and a positive ANA may identify OM and prevent overtreatment.

The significance of myositis autoantibodies in idiopathic inflammatory myopathy concomitant with interstitial lung disease

AIM

This study identified factors associated with interstitial lung disease (ILD) in patients with idiopathic inflammatory myopathy (IIM) based on the latest classification and recent advances in autoantibody serology.

METHODS

We retrospectively analyzed data of 173 patients who underwent complete myositis autoantibody serology examination in a medical center in Taiwan from July 2018 to February 2020. After exclusion of patients who did not receive a final diagnosis of IIM, clinical features, serology data, concomitant diseases, treatment, presence of respiratory failure, and mortality rate of the remaining 97 patients were analyzed.

RESULTS

Of IIM patients in our cohort, 47.4% had ILD. ILD was significantly associated with subtypes of IIM, older age of onset, presence of mechanic's hand, and presence of anti-Jo-1 and anti-Ro52 antibodies. Among five IIM subtypes, overlap myositis (OM) and dermatomyositis (DM) were significantly associated with a higher prevalence rate of ILD (67.5% in OM and 53.3% in DM). Among patients with OM, the presence of anti-Jo-1 (100%), anti-PL-7 (100%), and anti-EJ antibodies (77.8%) was most significantly associated with ILD.

CONCLUSION

The latest classification of IIM, older age of onset, presence of mechanic's hand, and presence of anti-Jo-1 and anti-Ro52 antibodies were significantly associated with ILD. Among five IIM subtypes, OM and DM had higher prevalence rate of ILD. Among OM patients, the presence of anti-Jo-1, anti-EJ, and anti-PL-7 antibodies was significantly associated with ILD. The study results may help physicians to timely screen and monitor pulmonary function in high-risk groups.

Inflammatory Myopathies: Utility of Antibody Testing

Inflammatory myopathies are a group of immune-mediated muscle disorders comprising dermatomyositis; polymyositis; overlap myositis, including antisynthetase syndromes and nonspecific myositis, immune-mediated necrotizing myopathies, and sporadic inclusion body myositis. They are now much more eloquently classified both pathologically and clinically because of the discovery of several myositis-specific and myositis-associated antibodies. These antibodies also aid in choosing the best treatment options in each case. Based on the initial classifications of inflammatory myopathies, inclusion body myositis, overlap myositis, and necrotizing myositis were all included in the polymyositis group. This article discusses cases, diagnostic tools, associated antibodies, and pathology.

The Brazilian Society of Rheumatology recommendations on investigation and diagnosis of systemic autoimmune myopathies

BACKGROUND

This research is recommended by the Myopathy Committee of the Brazilian Society of Rheumatology for the investigation and diagnosis of systemic autoimmune myopathies. BODY: A systematic literature review was performed in the Embase, Medline (PubMed) and Cochrane databases, including studies published until October 2018. PRISMA was used for the review, and the articles were evaluated, based on the Oxford levels of evidence. Ten recommendations were developed addressing different aspects of systemic autoimmune myopathy investigation and diagnosis.

CONCLUSIONS

The European League Against Rheumatism/ American College of Rheumatology (EULAR/ACR) classification stands out for the diagnosis of systemic autoimmune myopathies. Muscular biopsy is essential, aided by muscular magnetic resonance images and electroneuromyography in complementary research. Analysis of the factors related to prognosis with the evaluation of extramuscular manifestations, and comorbidities and intense investigation regarding differential diagnoses are mandatory.

Frequencies and clinical associations of myositis-related antibodies in The Netherlands: A one-year survey of all Dutch patients

Idiopathic inflammatory myopathies (IIM) are a heterogeneous group of connective tissue diseases, collectively known as myositis. Diagnosis of IIM is challenging while timely recognition of an IIM is of utter importance considering treatment options and otherwise irreversible (severe) long-term clinical complications. With the EULAR/ACR classification criteria (2017) considerable advancement has been made in the diagnostic workup of IIM. While these criteria take into account clinical parameters as well as presence of one autoantibody, anti-Jo-1, several autoantibodies are associated with IIM and are currently evaluated to be incorporated into classification criteria. As individual antibodies occur at low frequency, the development of line blots allowing multiplex antibody analysis has improved laboratory diagnostics for IIM. The Euroline myositis line-blot assay (Euroimmun) allows screening and semi-quantitative measurement for 15 autoantibodies, i.e. myositis specific antibodies (MSA) to SRP, EJ, OJ, Mi-2α, Mi-2β, TIF1-γ, MDA5, NXP2, SAE1, PL-12, PL-7, Jo-1 and myositis associated antibodies (MAA) to Ku, PM/Scl-75 and PM/Scl-100. To evaluate the clinical significance of detection and levels of these autoantibodies in the Netherlands, a retrospective analysis of all Dutch requests for extended myositis screening within a 1 year period was performed. A total of 187 IIM patients and 632 non-IIM patients were included. We conclude that frequencies of MSA and MAA observed in IIM patients in a routine diagnostic setting are comparable to cohort-based studies. Weak positive antibody levels show less diagnostic accuracy compared to positive antibody levels, except for anti-NXP2. Known associations between antibodies and skin involvement (anti-MDA5, anti-TIF1-γ), lung involvement (anti-Jo-1), and malignancy (anti-TIF1-γ) were confirmed in our IIM study population. The availability of multiplex antibody analyses will facilitate inclusion of additional autoantibodies in clinical myositis guidelines and help to accelerate diagnosing IMM with rare but specific antibodies.

[What's new in internal medicine?]

What's new in internal medicine will be dedicated to three topics: i) inflammatory myopathies constituting a heterogenous group of diseases whose clinical manifestations, immunological abnormalities, treatment response and outcomes vary widely; ii) alterations of gut microbiota contributing to the occurrence or development of a range of conditions, including autoimmune diseases for which further work is necessary to understand the correlation of dysbiosis with these diseases; iii) the reciprocal relationship between obesity, metabolic syndrome, atherosclerosis and autoimmune diseases. New data concerning systemic sclerosis, cutaneous vasculitis, adult Still's disease, autoantibodies anti DFS70, Epstein Barr virus and autoimmune diseases were also highlighted.