Autoimmune Inflammatory Myopathies Research Articles

Increased Cytokine Levels in Seronegative Myositis: Potential Th17 Immune Response Implications

Th17 cells are known for producing IL-17 and their role in the pathogenesis of various autoimmune diseases, including myositis. Likewise, the participation of the IL-23/IL-17 pathway in autoimmunity has been confirmed. In this study, we aimed to evaluate the behavior of cytokines in myositis, focusing on the autoantibodies profile and the myositis core set measures. Twenty-five myositis patients were enrolled in this cross-sectional study. An expert rheumatologist evaluated the myositis core set measures. Serum levels of cytokines and chemokines were quantified using the LEGENDplex Multi-Analyte Flow Assay Kit from BioLegend. The autoantibodies detection was carried out using the line-blot assay kit Euroline: Autoimmune Inflammatory Myopathies from EUROIMMUN. We found higher serum levels of IL-33, CXCL8, IL-6, IL-23, and IL-12p70 in seronegative patients. A multiple linear regression analysis revealed that MYOACT scores could be predicted by the increment of IL-23 and the decrement of CCL2, IL-10, and CXCL8 serum levels. These findings suggest that the immune response in seronegative myositis patients exhibits an IL-23-driven Th17 immune response. The relevance of this discovery lies in its potential therapeutic implications. Insights into the IL-23-driven Th17 immune response in seronegative patients highlight the potential for targeted therapies aimed at modulating Th17 activity.

Anti-synthase syndrome associated with SARS-Cov-2 infection

BackgroundAnti-synthetase syndrome (AS) is a rare autoimmune idiopathic inflammatory myopathy (IIM) with diverse manifestations, including arthritis, interstitial lung disease (ILD), Raynaud’s phenomenon, unexplained persistent fever, and mechanic’s hands.Case presentationWe present the case of a 72-year-old woman, previously healthy, who was admitted to our hospital for treatment of cough and rapid breathing. The patient had elevated white blood cells and C-reactive protein, and tested negative for severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2). She was initially diagnosed with community-acquired pneumonia and received tamoxifen for anti-infection treatment, but her dystonia worsened. She eventually required non-invasive ventilator support, tested positive for SARS-Cov-2 again, and started antiviral therapy, corticosteroids to reduce alveolar effusion, anticoagulation, and other treatments. However, her condition continued to deteriorate, with the lowest oxygenation index reaching only 80mmHg. Ultimately, she underwent tracheal intubation and mechanical ventilation. Chest CT revealed rapid progressive interstitial changes in her lungs, and her hands showed noticeable fraternization changes. At this point, we suspected that the novel coronavirus infection might be associated with autoimmune diseases. The patient’s autoimmune antibody spectrum showed positive results for anti-recombinant RO-52 antibody and myositis-specific antibody anti-alanyl tRNA synthetase (anti-PL-12). The patient was treated with dexamethasone sodium phosphate for anti-inflammatory and anti-fibrotic effects. After successful extubation, the patient was discharged with only oral prednisone tablets at a dose of 30 mg.ConclusionsThis case presents an early diagnosis and successful treatment of anti-synthetase syndrome combined with SARS-Cov-2 infection, emphasizing the importance of comprehensive physical examination. Additionally, it highlights the rapid progression of interstitial lung disease under SARS-Cov-2 infection, which is often difficult to distinguish on imaging. In cases where treatment for SARS-Cov-2 infection is ineffective, early screening for autoimmune diseases is recommended. As there is currently no standardized method for treating AS-ILD, the successful treatment of this case provides a reference for clinical research on anti-synthetase syndrome in the later stage.

OA15 Missing the wood(-y induration) for the trees

OA15 Missing the wood(-y induration) for the trees

Update on autoantibodies and related biomarkers in autoimmune inflammatory myopathies.

Purpose of review This manuscript reviews recently published advances in the identification of autoimmune inflammatory myopathies (AIM)-specific and AIM-related autoantibodies considered of value in the workup of patients suspected of having AIM. Newer autoantibodies, developments, and advances in the methodology of testing, the gaps and pitfalls in using these assays as diagnostic biomarkers, and the importance of considering overlap diseases and unique clinical AIM phenotypes are discussed. Recent findings Summary The spectrum of autoantibodies and related biomarkers in AIM continues to expand. Many of these have clear clinical implications in regard to subsets and overlap conditions of AIM, associated malignancy and pathological findings.

Anti-Cytosolic 5'-Nucleotidase 1A in the Diagnosis of Patients with Suspected Idiopathic Inflammatory Myopathies: An Italian Real-Life, Single-Centre Retrospective Study.

Anti-cytosolic 5'-nucleotidase 1A (anti-cN1A) antibodies were proposed as a biomarker for the diagnosis of inclusion body myositis (IBM), but conflicting specificity and sensitivity evidence limits its use. Our study aimed to assess the diagnostic accuracy of anti-cN1A in a cohort of patients who underwent a myositis line immunoassay for suspected idiopathic inflammatory myopathies (IIM). We also assessed the agreement between two testing procedures: line immunoassay (LIA) and enzyme-linked immunoassay (ELISA). We collected retrospective clinical and serological data for 340 patients who underwent a myositis antibody assay using LIA (EUROLINE Autoimmune Inflammatory Myopathies 16 Ag et cN-1A (IgG) line immunoassay) and verification with an anti-cN1A antibody assay using ELISA (IgG) (Euroimmun Lubeck, Germany). The serum samples of 20 (5.88%) patients (15 females, 5 males, mean age 58.76 ± 18.31) tested positive for anti-cN1A using LIA, but only two out of twenty were diagnosed with IBM. Seventeen out of twenty tested positive for anti-cN1A using ELISA (median IQR, 2.9 (1.9-4.18)). Our study suggests excellent concordance between LIA and ELISA for detecting anti-cN1A antibodies. LIA may be a rapid and useful adjunct, and it could even replace ELISA for cN1A assay. However, the high prevalence of diseases other than IBM in our cohort of anti-cN1A-positive patients did not allow us to consider anti-cN1A antibodies as a specific biomarker for IBM.

Prevalence of myositis specific and associated antibodies in a cohort of patients affected by idiopathic NSIP and no hint of inflammatory myopathies.

The presence of interstitial lung disease (ILD) is a common and fearsome feature of idiopathic inflammatory myopathies (IIM). Such patients show radiological pattern of non-specific interstitial pneumonia (NSIP). The present study aimed to assess the prevalence of myositis-specific and myositis-associated antibodies (MSA and MAA) in a cohort of patients with a previous diagnosis of NSIP and no sign or symptom of IIM. Secondly, it will be assessed whether patients displaying MSA and/or MAA positivity have a worse or a better outcome than idiopathic NSIP. All patients affected by idiopathic NSIP were enrolled. MSA and MAA were detected using EUROLINE Autoimmune Inflammatory Myopathies 20 Ag (Euroimmun Lubeck, Germany), line immunoassay. A total of 16 patients (mean age 72 ± 6.1years old) were enrolled. Six out of 16 patients (37.5%) had significant MSA and/or MAA positivity: one displayed positivity of anti-PL-7 (+ +), one of anti-Zo (+ +), anti-TIF1γ (+ + +) and anti-Pm-Scl 75 (+ + +), one of anti-Ro52 (+ +), one of anti-Mi2β (+ + +), one of anti-Pm-Scl 75 (+ + +) and the latter of both anti-EJ (+ + +) and anti-Ro52 (+ + +).Two out of 7 seropositive patients showed a significant impairment of FVC (relative risk 4.8, 95% CI 0.78-29.5; p = 0.0350). Accordingly, among the 5 patients that started antifibrotic treatment during the observation time, 4 were seronegative. Our findings highlighted a potential autoimmune or inflammatory in idiopathic NSIP patients and also in those without significant rheumatological symptoms. A more accurate diagnostic assessment may ameliorate diagnostic accuracy as well as may provide new therapeutic strategy (antifibrotic + immunosuppressive). A cautious assessment of NSIP patients with a progressive and non-responsive to glucocorticoids disease course should therefore include an autoimmunity panel comprising MSA and MAA.

Becker Muscular Dystrophy Accompanied by Anti-HMGCR Antibody-positive Immune-mediated Necrotizing Myopathy.

Becker muscular dystrophy (BMD) is an X-linked neuromuscular disease characterized by progressive muscle weakness that currently has no cure. Immune-mediated necrotizing myopathy (IMNM) is a type of autoimmune inflammatory myopathy characterized by proximal muscle weakness that is treated with immunosuppressive therapy. We herein report a patient diagnosed with BMD complicated with IMNM by a pathological analysis. Notably, the patient had an elevated serum anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase antibody level. Oral glucocorticoid and methotrexate treatment partially improved the muscle weakness with decreased levels of serum creatine kinase. An accurate diagnosis is important for therapeutic decisions in these complicated cases.

Atypical Overlapping Features Complicating Diagnoses of Dysferlinopathy and Immune-Mediated Necrotizing Myopathy. (P6-8.006)

<h3>Objective:</h3> To present overlapping features and atypical characteristics of dysferlinopathy and immune-mediated necrotizing myopathy (IMNM). <h3>Background:</h3> Dysferlinopathy typically presents with early onset progressive muscle weakness that can be proximal or distal. Definitive diagnosis is made with DYSF gene testing. Treatment is supportive. IMNM is an autoimmune inflammatory myopathy that affects older individuals and is often associated with occult malignancy. Aggressive immunotherapy improves outcomes. Muscle biopsy (MBx) reveals inflammatory infiltrates in both conditions. <h3>Design/Methods:</h3> N/A <h3>Results:</h3> <h3>Case 1:</h3> A 35-year-old man presented with subacute progressive limb weakness and elevated creatine phosphokinase (CPK) &gt;8,000 units/L. MBx showed necrotizing myopathy and sarcolemmal C5b-9 staining; dystrophy stains were omitted due to the patient’s age and subacute symptoms. Anti-signal recognition peptide (SRP) and anti-3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) antibodies and malignancy screen were negative. The patient was initially diagnosed with seronegative IMNM and treated with steroids, methotrexate and IVIG without improvement. He was subsequently diagnosed with dysferlinopathy based on genetic testing showing double heterozygous pathogenic DYSF gene mutations. <h3>Case 2:</h3> An 18-year-old man presented with 3-years of progressive proximal limb weakness associated with Gower’s sign and elevated CPK &gt;10,000 units/L. Broad muscular dystrophy genetic testing was negative. MBx showed necrotizing myopathy and sarcolemmal C5b-9 staining suggestive of IMNM. Anti-SRP and anti-HMGCR antibodies, serum paraneoplastic panel, and malignancy screening with tumor markers, contrasted CT imaging, and scrotal ultrasound were negative. The patient was diagnosed with early-onset seronegative IMNM. CPK improved and symptoms stabilized with prednisone, methotrexate and IVIG therapy. <h3>Conclusions:</h3> Dysferlinopathy and IMNM can have overlapping clinical features and MBx findings. Heightened awareness of atypical features aids in timely diagnosis. Accurate diagnosis of dysferlinopathy based on genetic testing limits further invasive workup and the side effects of ineffective empiric therapy, whereas early diagnosis of IMNM allows for prompt immunotherapy which is shown to improve prognosis. <b>Disclosure:</b> Dr. Stout has nothing to disclose. Dr. Su has nothing to disclose.

E079 Preliminary analysis of autoantibody profiles of autoimmune inflammatory myopathies: study from a single North Indian tertiary care centre

Abstract Background/Aims Studies in autoimmune inflammatory myositis (AIM) have shown a strong role of autoantibodies in the diagnosis and prognosis of patients with myositis. This ongoing study shares the preliminary data of 139 patients with AIM from a North Indian tertiary care centre. This prospective, observational study was conducted at a 1250-bedded hospital to assess the prevalence of myositis-specific antibodies (MSA) and myositis-associated antibodies (MAA) in patients from the Indian subcontinent with AIM and the correlation of these antibodies with clinical features. Methods From November 2016 to September 2022, patients with AIM (satisfying the Bohan and Peter criteria of 1975) attending the Rheumatology and Clinical Immunology Department of Medanta Hospital were included after taking their informed consent, and divided into subgroups as dermatomyositis (DM), polymyositis (PM), CTD-associated myositis (CTD-M), cancer-associated myositis (CAM), and juvenile myositis (JM). The Institutional Ethics Committee approved the study. Clinical data and sera from patients were collected and analysed. Results The study included 139 individuals with a mean age of 45.4 years. Fifty-two had DM, 49 had PM, 25 had CTD-M, 6 had CAM, and 7 had JM. ANA positivity was found in 67.70%, MSA in 22.3%, MAA in 25.4%, and both in 12.3%. Antibodies against Mi-2 were identified in 13 (28.9%) patients, Jo-1 in 14 (32.50%), PL-7 in 3 (6.7%), PL-12 in 4 (8.9%), SRP in 9 (20%), and MDA-5 and NXP2 in 1 (2.2%) patient each. Antibodies against Ro were found in 28 (57.1%) of the patients, RNP in 8 (16.3%), and PM-Scl in 9 (18.4%). Mi-2 antibodies were mostly identified in DM patients and were significantly associated with skin rash. SRP positivity was mostly found mainly in PM. Raynaud's and ILD were linked to the presence of Jo-1 and Ro antibodies. Malignancy screening was negative in NXP2 and TIF1γ antibody-positive patients. Conclusion MSA was found in 22.3% of cases and MAA in 25.4%. Mi-2 antibodies were linked to rash, but none had ILD, whereas Jo-1 antibodies were linked to mechanic hands, arthritis, and ILD. We aim to gather more strong results in the future as additional patients are recruited in this continuing trial. Disclosure S. Dhuria: None. P. Khatri: None. N. Negalur: None. K. Telang: None. S. Ghosh: None. D. Yadavalli: None. V. Singal: None. R. Gupta: None.

Osteonecrosis in patients with juvenile dermatomyositis: is it associated with anti-MDA5 autoantibody?

Dear Editor, Data on osteonecrosis (ON) in JDM are limited [1]. It is usually considered as the result of corticosteroid therapy. Herein, we report a case series of five patients among a cohort of 71 patients with JDM who developed severe ON. All of them had anti-MDA5 positive JDM, which suggests that MDA5-positive JDM patients may have predisposing factors for the development of ON. We retrospectively reviewed the cohort of 71 patients with JDM followed in the Paris referral center for Rare Paediatric Rheumatism and systemic autoimmune diseases (RAISE), between December 2010 and December 2021. Inclusion criteria were: (i) diagnosis of JDM, according to Bohan and Peter criteria with a follow-up of at least 2 years; and (ii) ON diagnosed by bone MRI. During the period of inclusion, myositis-specific antibodies (MSA) were searched once for in all the patients by dot-blot immunoassay using Euroline Autoimmune Inflammatory Myopathies 16 Ag (Euroimmun) and Blue Diver PMS12-24 (D-Tek). IFN-α2 protein concentration was measured by SIMOA assay (Quanterix Homebrew). All statistical analyses were performed using GraphPad Prism (version 9.1.1). After parental consent, patients were registered in the French rare diseases National database (BAMARA). This study was approved by the Ethics board of Necker hospital.

Objectivity, practicality, and significance of practice guidelines for the practicing neurologists: What we learnt from consensus criteria in CIDP, Myasthenia Gravis and Inflammatory Myopathies.

The value of practice guidelines in the three most common autoimmune neuromuscular disorders, namely Chronic Inflammatory Demyelinating Polyneuropathy (CIDP), Myasthenia Gravis (MG) and Autoimmune Inflammatory Myopathies (AIM), has been extensively debated regarding their usefulness in clinical practice, objectivity and universal value considering that guidelines are also established regionally in certain countries. This commentary highlights common concerns on how guidelines are presently generated, pointing out: (a) non-sufficient diversity among Task-Force members to identify and address not only routine clinical and electrophysiology issues but also immunology, imaging, pathology, biomarkers, epidemiology or treatment economics; (b) Task-Force being often comprised by the same or seemingly like-minded members conveying the erroneous impression that experts with opposing views might have been excluded, even if this is clearly not the case; and (c) relying on web-based registries or retrospective data collections from heterogeneous sources. As a result, the existing practice guidelines in CIDP, MG and AIM remain an unfinished business but an excellent base for further enhancement. Guidelines can be extremely helpful not only for clinical trials but also in clinical practice if viewed as a living document with continuously updated versions by experts even with opposing views with precise information on diagnostics, pathomechanisms, therapeutic schemes, evolving biomarkers and economics of new therapies with validation of the post-guidelines criteria. Geographic diversity should be taken into consideration because the availability of biomarker testing, and therapies differ among countries. Patient preferences need to be also considered in therapeutic guidelines because newly marketed drugs offer more options steadily changing the therapeutic algorithms in autoimmune neuromuscular diseases generating also questions as to whether they also influence decisions on insurance coverage. Collectively, these startup considerations are aimed to make practice guidelines more objective, widely acceptable worldwide and more practical or easier to follow in clinical practice.

Dermatomyositis Presenting as Pseudo-angioedema

Dermatomyositis is an autoimmune inflammatory myopathy that has a heterogeneous clinical presentation, which can make it difficult to diagnose. We present the first case report of Wong-type dermatomyositis presenting with pseudo-angioedema. A 65-year-old man presented with several months of facial swelling, dysphagia, and dysarthria. The patient developed a diffuse cutaneous rash, periorbital swelling, and proximal muscle weakness. Skin biopsy was consistent with a diagnosis of Wong-type dermatomyositis.

Aminoacyl-tRNA synthetases in human health and disease.

The Aminoacyl-tRNA Synthetases (aaRSs) are an evolutionarily ancient family of enzymes that catalyze the esterification reaction linking a transfer RNA (tRNA) with its cognate amino acid matching the anticodon triplet of the tRNA. Proper functioning of the aaRSs to create aminoacylated (or "charged") tRNAs is required for efficient and accurate protein synthesis. Beyond their basic canonical function in protein biosynthesis, aaRSs have a surprisingly diverse array of non-canonical functions that are actively being defined. The human genome contains 37 genes that encode unique aaRS proteins. To date, 56 human genetic diseases caused by damaging variants in aaRS genes have been described: 46 are autosomal recessive biallelic disorders and 10 are autosomal dominant monoallelic disorders. Our appreciation of human diseases caused by damaging genetic variants in the aaRSs has been greatly accelerated by the advent of next-generation sequencing, with 89% of these gene discoveries made since 2010. In addition to these genetic disorders of the aaRSs, anti-synthetase syndrome (ASSD) is a rare autoimmune inflammatory myopathy that involves the production of autoantibodies that disrupt aaRS proteins. This review provides an overview of the basic biology of aaRS proteins and describes the rapidly growing list of human diseases known to be caused by genetic variants or autoimmune targeting that affect both the canonical and non-canonical functions of these essential proteins.

Thrombin generation potential is increased in patients with autoimmune inflammatory myopathies

PurposeDermatomyositis and polymyositis (DM/PM) are rare autoimmune inflammatory myopathies, characterized by an increased risk of cardiovascular and thromboembolic events, likely related to the prothrombotic plasma properties. The aim of this study was to assess the in vitro thrombin generation profile as a biomarker of plasma procoagulant properties in DM/PM patients. MethodsIn 58 clinically stable DM/PM patients and 67 controls matched for sex, age, body mass index, we measured plasma thrombin generation potential using the Calibrated Automated Thrombinography (CAT) and analyzed its relationship with clinical disease characteristics, including autoantibodies profile. ResultsPatients with DM/PM had a 21% increase in endogenous thrombin potential (ETP), 36% higher peak thrombin concentration, and 11% faster thrombin generation, compared to controls (p ​< ​0.001, all, also after adjustment for potential confounders). Interestingly, although both diseases did not differ in thrombin generation potential, heterogenous variables predicted elevated ETPs in both of them. In DM, that was higher fibrinogen, C-reactive protein, and total cholesterol, whereas in PM, presence of arthritis and increased blood platelet count. Surprisingly, thrombin formation capacity remained in a robust inverse relationship with serum troponin (r ​= ​−0.67, p ​< ​0.001) in the patient group. ConclusionsDM/PM patients are characterized by an increased thrombin generation potential, suggesting prothrombotic plasma properties in both diseases. However, more studies are needed to verify its rationale and role in DM/PM clinical course and unfavorable clinical outcomes.

Myositis-specific autoantibodies and their clinical associations in idiopathic inflammatory myopathies: results from a cohort from China.

The purpose of this study was to determine the incidence of myositis-specific autoantibodies (MSAs) in a cohort of Chinese patients with idiopathic inflammatory myopathies (IIMs) and to examine their associations with clinical characteristics and long-term prognosis. Adult patients with confirmed IIMs (n = 515) were studied using the EUROLINE Autoimmune Inflammatory Myopathies 16 Ag (IgG) commercial line blot test to detect MSAs/myositis-associated autoantibodies. We collected the laboratory data and clinical features. The frequencies of MSAs and their associations with clinical phenotypes were evaluated using SPSS 25.0 software. At least one MSA was found in 88.2% of the 515 IIM patients studied. The most frequently detected MSAs were anti-MDA5 (25.4%), anti-Jo-1(15.1%), and anti-EJ (9.5%). Autoantibodies against MDA5, TIF1-γ, and NXP2 were significantly correlated with cutaneous involvement (P < 0.001 or P < 0.01). Anti-TIF1-γ-positive patients had an enhanced risk of malignancy (OR = 3.51). Rapidly progressive interstitial lung disease (RP-ILD) was significantly correlated with anti-MDA5 (P < 0.0001). Anti-MDA5-positive patients had increased risks of elevated ferritin and decreased lymphocyte counts (OR = 5.65 and OR = 5.74, respectively). Kaplan-Meier survival revealed that individuals positive for anti-MDA5, especially anti-MDA5 combined with anti-Ro52, had the worst prognosis (P = 0.03). Male, old age, RP-ILD, and elevated ferritin were identified as predictors of poor prognosis in IIM patients. MSAs were present in the majority of the IIM patients. Numerous MSAs were independent factors for identifying exceptional clinical phenotypes. Key Points • This is a large Chinese cohort of IIM patients to analyze possible associations of MSA profiles with clinical characteristics, aiming to provide valuable data for clinical work. • MSAs were present in approximately 90% of IIM patients with distinct clinical subsets. Patients with anti-Jo-1 and non-anti-Jo-1 ASAs exhibited similar characteristics. • The association of anti-TIF1-γ with malignancy was confirmed in adult patients. Patients with IIMs who were positive for both anti-Ro52 and anti-MDA5 had a worse prognosis. • Male, RP-ILD, and heliotrope rash were independent risk factors for a poor prognosis in patients with IIMs.

Autoimmune Idiopathic Inflammatory Myopathies: Pharmacological Differences and Similarities by Type of Myositis and by Sociodemographic Variables.

Objective Autoimmune idiopathic inflammatory myopathies (IIMs) are a group of pathologies that are generally characterized by muscle weakness. Their treatment involves glucocorticoids and immunosuppressants. The aim was to identify differences and similarities in the pharmacological management of a group of patients with autoimmune IIMs according to the type of disease, sex, age group, and city of residence in Colombia from 2020 to 2021. Methods This cross-sectional study identified medication prescription patterns for outpatient use in patients with autoimmune IIMs between 2020 and 2021 based on a population database of 8.5 million Colombians affiliated with the Colombian health system. Sociodemographic and pharmacological variables were considered. Results A total of 671 patients with autoimmune IIMs were identified, with a median age of 57 years, and 70.9% were women. Overlap myositis was the most frequent disease (31.4%). A total of 91.5% of the patients received pharmacological treatment, mainly systemic glucocorticoids (78.5%), conventional disease-modifying antirheumatic drugs (DMARDs) (74.1%), immunosuppressants (9.1%), and biological DMARDs (3.7%). Pharmacological management predominated among patients with overlap myositis, those who lived in cities, and those affiliated with the contributory regime of the Colombian health system. Conventional DMARDs were prescribed mainly to women and to those older than 65 years. Conclusions Patients with autoimmune IIMs are not treated homogeneously. The pattern of drug use varies according to the type of IIM, sex, age group, city, and health system regime affiliation.

Effective therapy of polymyositis in mice via selective inhibition of the immunoproteasome.

Polymyositis (PM) is a chronic autoimmune inflammatory myopathy resulting in muscle weakness. The limited approved therapies and their poor efficacy contribute to its comorbidity. We investigated the therapeutic use of ONX 0914 and KZR-616, selective inhibitors of the immunoproteasome, in C protein-induced myositis (CIM), a mouse model of PM that closely resembles the human disease. Diseased mice (day 13 postimmunization) were treated with 10 mg/kg ONX 0914, KZR-616, or vehicle on alternate days until day 28. Endpoints included muscle strength assessed by a grip strength meter, serum creatine kinase activity, histology, and immunohistochemistry analysis. Treatment with ONX 0914 or KZR-616 prevented the loss of grip strength in mice after CIM induction, while vehicle-treated animals displayed progressive muscle weakness. Immunoproteasome inhibition lowered PM-associated leukocyte infiltration of the muscle and prevented increased serum creatine kinase levels. LMP7-deficient mice were resistant to CIM induction, as they showed no alterations in grip strength or creatine kinase (CK) levels or muscular alterations. In conclusion, selective inhibition of the immunoproteasome displays therapeutic efficacy in a preclinical mouse model of PM with suppression of muscle inflammation and preservation of muscle strength. Positive results from this study support the rationale for using KZR-616 in clinical studies.

Complement in autoimmune inflammatory myopathies, the role of myositis-associated antibodies, COVID-19 associations and muscle amyloid deposits

Introduction The inflammatory myopathies (IM) have now evolved into distinct subsets requiring clarification about their immunopathogenesis to guide applications of targeted therapies Areas covered Immunohistopathologic criteria of IM with focus on complement, anti-complement therapeutics and other biologic immunotherapies. The COVID19-triggered muscle autoimmunity along with the correct interpretation of muscle amyloid deposits are discussed. Expert opinion The IM, unjustifiably referred as idiopathic, comprise Dermatomyositis (DM), Necrotizing Autoimmune Myositis (NAM), Anti-synthetase syndrome-overlap myositis (Anti-SS-OM), and Inclusion-Body-Myositis (IBM). In DM, complement activation with MAC-mediated endomysial microvascular destruction and perifascicular atrophy is the fundamental process, while innate immunity activation factors, INF1 and MxA, sense and secondarily enhance inflammation. Complement participates in muscle fiber necrosis from any cause and may facilitate muscle-fiber necrosis in NAM but seems unlikely that myositis-associated antibodies participate in complement-fixing. Accordingly, anti-complement therapeutics should be prioritized for DM. SARS-CoV-2 can potentially trigger muscle autoimmunity but systematic studies are needed as the reported autopsy findings are not clinically relevant. In IBM, tiny amyloid deposits within muscle fibers are enhanced by inflammatory mediators contributing to myodegeneration; in contrast, spotty amyloid deposits in the endomysial connective tissue do not represent “amyloid myopathy” but only have diagnostic value for amyloidosis due to any cause.

Summarized Review on Dermatomyositis: Demonstrating Modes of Diagnosis &amp; Current Therapeutic Managements

Dermatomyositis (DM) is an autoimmune idiopathic inflammatory myopathy characterized by distinctive skin lesions, specific autoantibodies, and, most importantly, subacute symmetrical proximal muscle weakness and inflammation. Clinically amyopathic DM is a type of DM that presents with only characteristic skin lesions and no muscle disease. Heliotrope rash, erythematous rash over the face, erythematous scaly papules over the interphalangeal and metacarpophalangeal joints (Gottron's papules), erythema over the same joints (Gottron's sign), photosensitive pruritic erythema over the anterior chest and neck (V-sign), erythema extending to the shoulders and malignancy, respiratory disease, and cardiac disease are all causes of mortality and morbidity in dermatomyositis. Depending on the patient's parameters, management may include photoprotection and medications such as systemic corticosteroids, antimalarials, mycophenolate mofetil, biologicals, and IV immunoglobulins. Keywords: dermatomyositis, Gottron’s papules, heliotrope rash, inflammatory myopathy.

Myositis-specific antibodies and clinical characteristics in patients with autoimmune inflammatory myopathies: reported by the Argentine Registry of Inflammatory Myopathies of the Argentine Society of Rheumatology.

To describe clinical features in patients with inflammatory myopathies (IMs) from the Argentine Registry of Inflammatory Myopathies, and their relationship with myositis-specific antibodies (MSAs). This cross-sectional study included 360 adult patients with dermatomyositis (DM), polymyositis (PM), and inclusion body myositis. Demographics, clinical, and serological characteristics were retrospectively recorded (2016-2019). MSAs were determined by immunoblotting. Patients who were positive for anti-Jo-1, Mi-2, and MDA5 were compared against a group of patients, taken as reference group, who were negative for all MSAs. Women 72%, median age at diagnosis was 47.3years (18-82). The most frequent subtypes were DM (43.9%) followed by PM (30%).The most frequent MSAs were anti-Jo-1 (51/317), 16.1%; MDA5 (12/111), 10.8%, and Mi-2 (23/226), 10.2%. Anti-Jo-1 was associated (p < 0.05) with a higher frequency of chronic disease course, interstitial lung disease (ILD), arthritis, and mechanic's hands. Anti-Mi-2 was found in patients who had higher frequency of skin manifestations and higher CK values (p < 0.001). Patients with anti-MDA5 had normal or low CK levels. Anti-MDA5 was associated (p < 0.05) with skin manifestations, arthritis, and ILD. The rest of MSAs had frequencies lower than 8%. Anti-TIF1ϒ was found in eight DM patients and one had cancer. Anti-SRP was found in seven patients who had PM and elevated CK. Anti-Jo-1 was the most frequent MSA, and was associated with ILD; MDA5 was associated with CADM and ILD, and Mi-2, with classical DM. Despite the different prevalence with respect to other cohorts, the clinical characteristics for each MSA group were similar to the data reported in other studies. Key Points • This study describes the prevalence of MSAs in the Argentine Registry of IMs. • Anti-Jo-1 and anti-MDA5 were associated with ILD. • Anti-Mi-2 was the third most frequent MSA, associated with classical DM.