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.

Diffusion tensor imaging of vastus lateralis in patients with inflammatory myopathies.

Inflammation in patients with myositis would increase diffusion of water molecules across sarcolemma that could be detected with the help of diffusion tensor imaging (DTI). We aimed to determine an association between DTI of vastus lateralis (VL) and histopathological findings in cases of myositis and to estimate diagnostic performance of different MRI variables in predicting histopathological outcomes. This prospective cross-sectional observational study included 43 patients with myositis. MRI of bilateral thighs with DWI/DTI protocol was performed in all the patients. Thirty-three patients further underwent biopsy of right VL muscle. Imaging analysis included grading of "Muscle oedema" based on signal intensity (SI) and extent and "fatty infiltration" based on extent on conventional sequences and, acquiring DWI and DTI parameters. Gold standard method to determine inflammation in muscles was histopathological examination. Comparison of DTI/DWI variables with clinical and histopathological variables was done. The average DWI apparent diffusion coefficient (ADC) and DTI ADC values in the patients were 1.77 ± 0.35 and 2.06 ± 0.35 respectively. The average functional anisotropy (FA) was 0.39 ± 0.17 and, the 3 eigenvalues in the patients were 2.96 ± 0.63, 2.05 ± 0.32, and 1.20 ± 0.39 respectively. VL oedema SI weighted score was the best parameter for predicting effaced fascicular architecture and marked lymphocytic inflammation in endomysium on histopathology. VL fatty infiltration weighted score was the best parameter in predicting perifascicular atrophy. Addition of DWI or DTI didn't add significantly in determining active inflammation in cases of myositis.

Fatal Case of Immune-Related Myocarditis and Myositis Due to Treatment with Immune Checkpoint and Tyrosine Kinase Inhibitors.

Immune checkpoint inhibitor and tyrosine kinase inhibitor combinations have become the new standard of care in the first-line treatment of metastatic clear cell renal cell carcinoma. However, there is a growing concern regarding severe immune-related adverse events. A 78-year-old man with metastatic clear cell renal cell carcinoma, treated with pembrolizumab and axitinib, was admitted to the emergency department 30 days after initiating treatment due to rapidly progressive myositis. Myocarditis with severe ventricular dysfunction was identified. Muscular biopsy findings were compatible with inflammatory myopathy associated with immune checkpoint inhibitors. Initial treatment with high-dose corticosteroids showed an insufficient response. Therapeutic escalation on the third day with methylprednisolone, immunoglobulin, and abatacept resulted in clinical improvement. On the eleventh day, a sudden malignant arrhythmia occurred, followed by cardiac arrest. This represents one of the first case reports describing myocarditis and myositis during treatment with pembrolizumab-axitinib. While immune checkpoint inhibitor may play a major role, it is also possible that the tyrosine kinase inhibitor, while attempting to promote immune modulation, also increases severe toxicities.

Myositis-Associated Interstitial Lung Disease: The Experience of a Tertiary Center.

Background: Interstitial lung disease (ILD) is a common extra-muscular manifestation of idiopathic inflammatory myopathies (IIMs), often associated with a poorer prognosis and increased mortality risk. Methods: This retrospective study aimed to characterize lung involvement and treatment response in an IIM cohort at a Portuguese tertiary center, followed between June 2016 and March 2024. We analyzed data from high-resolution computed tomography (HRCT) scans and pulmonary function tests (PFTs) to assess associations with autoantibody profiles and treatment regimens. Results: A total of 198 patients were included, with 69 (34.8%) exhibiting ILD. Antisynthetase syndrome (ASyS) and dermatomyositis were the most common diagnoses among IIM-ILD patients, with ASyS being significantly more frequent in this group than in non-ILD patients (p < 0.001). Anti-Jo1 and anti-MDA-5 antibodies were more frequent in ILD patients (p < 0.001 and p = 0.021), while anti-Mi2 antibodies were less common (p = 0.002). Non-specific interstitial pneumonia (NSIP) was the most common radiological pattern (69.5%). IIM-ILD patients presented with significantly lower forced vital capacity (FVC) and diffusing capacity of the lung for carbon monoxide (DLCO) compared to non-ILD patients (p < 0.001 for all values). Longitudinal analysis showed improved DLCO (p = 0.022) and stable or improved FVC (p = 0.097), especially with intravenous immunoglobulin (IVIg) and azathioprine (AZA). Combination therapies including IVIg with mycophenolate mofetil (MMF) or rituximab (RTX) also improved DLCO and FVC. Most ILD patients (89.6%) had stable HRCT patterns over time. Conclusions: Our findings highlight the potential for stabilizing or even improving lung function in IIM-ILD with appropriate immunosuppressive therapy, particularly with regimens incorporating IVIg and AZA, and combination therapies.

Short-term efficiency of plasma exchange in combination with immunosuppressants and/or biologics in the treatment of idiopathic inflammatory myopathy with rapidly progressive interstitial lung disease: a systematic review and meta-analysis

Objective Rapidly progressive interstitial lung disease (RP-ILD) is a frequent and serious manifestation of idiopathic inflammatory myopathy (IIM) associated with poor outcomes. Plasma exchange (PE) can quickly remove pathogenic substances from the blood. Therefore, PE may be efficacious in IIM patients who have elevated levels of autoantibodies, cytokines and chemokines, fighting for time for immunosuppressive therapy. However, the value of adding PE to immunosuppressants remains unclear. The purpose of this study was to determine the short-term outcomes, including the survival rate at 6 months and change of the laboratory data, of PE in combination with immunosuppressants and/or biologics in the treatment of IIM-RP-ILD. Methods We searched PubMed, Embase and Cochrane Library to find reports of interest published from inception to March 4, 2024. STATA 15.1 was used for data analysis. A fixed or random-effects model with inverse-variance weighting was used to estimate the pooled risk ratio (RR) and 95% confidence interval (CI). Results Two hundred and thirty studies were identified. Eleven studies, including five retrospective cohort studies, four case-control studies and two case series, were included. PE was performed on 114 patients. The survival rate at 6 months was 80% (95%CI = 64%–92%), with moderate heterogeneity (I 2=63.45%, p < 0.05). Moreover, the 6-month survival rate was significantly better in the PE group than in the non-PE group (RR, 1.34; 95% CI = 1.05–1.71, I 2=30.7%; p = 0.194). ILD-related serum markers, including ferritin, KL-6 and anti-MDA-5 antibody titres, were significantly suppressed by a series of PE treatments (p < 0.05). Conclusion The application of PE therapy plus treatment with corticosteroids, immunosuppressants and/or biologics was effective for patients with IIM-RP-ILD. PE may have additional supportive effect in intractable disease.

A combination of major histocompatibility complex (MHC) I overexpression and type I interferon induce mitochondrial dysfunction in human skeletal myoblasts.

The overexpression of major histocompatibility complex (MHC) I on the surface of muscle fibers is a characteristic hallmark of the idiopathic inflammatory myopathies (IIMs), collectively termed myositis. Alongside MHC-I overexpression, subtypes of myositis, display a distinct type I interferon (IFN) signature. This study examined the combinational effects of elevated MHC-I and type I IFNs (IFNα/β) on mitochondrial function, as mitochondrial dysfunction is often seen in IIMs. Human skeletal muscle myoblasts were transfected with an MHC-I isoform using the mammalian HLA-A2/Kb vector. Mitochondrial respiration, mitochondrial membrane potential, and reactive oxygen/nitrogen species generation were assessed with or without IFNα and IFNβ. We show that MHC-I overexpression in human skeletal muscle myoblasts led to decreased basal glycolysis and mitochondrial respiration, cellular spare respiratory capacity, adenosine triphosphate-linked respiration, and an increased proton leak, which were all exaggerated by type I IFNs. Mitochondrial membrane depolarization was induced by MHC-I overexpression both in absence and presence of type I IFNs. Human myoblasts overexpressing MHC-I showed elevated nitric oxide generation that was abolished when combined with IFN. MHC-I on its own did not result in an increased reactive oxygen species (ROS) production, but IFN on their own, or combined with MHC-I overexpression did induce elevated ROS generation. Surprisingly, we observed no gross changes in mitochondrial reticular structure or markers of mitochondrial dynamics. We present new evidence that MHC-I overexpression and type I IFNs aggravate the effects each has on mitochondrial function in human skeletal muscle cells, providing novel insights into their mechanisms of action and suggesting important implications in the further study of myositis pathogenesis.

Inflammatory Myopathies and Autoimmune Gluten-related Disorders: A Scoping Review of Pathophysiological Interconnections and Hypothesis

Introduction: Anecdotal reports describe patients with concurrent idiopathic inflammatory myopathy (IIM) and celiac disease (CeD) in whom the introduction of a gluten-free diet led to dramatic improvement of myositis. We first systematically reviewed all peer-reviewed publications on concomitant IIM and duodenal biopsy-verified CeD. The collected evidence was suggestive of associations between myositis disease activity and gluten exposure in some patients with IIM-CeD. Objective/Methods: To investigate possible explanations for the observations, an exploratory review of basic pathophysiological relationships between IIM and gluten-related disorders was performed using a combined strategy of systematic and non-systematic literature searches and forward and backward citation tracking. Results: The investigations revealed close pathophysiological associations between IIM and the autoimmune gluten-related disorders CeD, dermatitis herpetiformis, and gluten ataxia. Common traits include shared genetic predisposition through HLA-DQ2.5/-DQ8, disease activity-associated autoantibodies, histopathological parallels with inflammatory cell infiltrates, and similarly distributed structural homologous transglutaminases (TGs). HLA-DQ2.5-restricted gluten-specific CD4+ T cells of a rare, uniform phenotype are reported in CeD and connective tissue disease. Expanded T-cell clones with identical phenotypes and CDR3β motifs indicate the presence of a continuous, antigen-driven T-cell response. Conclusion: The investigations revealed that the main components involved in the adaptive immune response in the CeD gut may be present in HLA-DQ2.5+/-DQ8+ IIM muscle. The collected evidence supports the notion that in some genetically predisposed patients with IIM, gluten may act as an exogenous antigen driving myositis. Further Research/Clinical Implications: To test the above hypothesis, clinical trials combined with immunological studies are needed. Meanwhile, the inclusion of HLA-DQ typing may be justified, and subsequent small-intestinal biopsies in HLA-DQ2.5/8+ individuals with IIM.

Methotrexate: Use in the Post Dobbs v. Jackson Era.

Methotrexate is one of the most frequently used medications for the treatment of rheumatic diseases. Although initially developed for use as chemotherapy for both solid and hematologic malignancies, it was used as early as the 1960s with success for rheumatoid arthritis (RA) and psoriatic arthritis, ultimately being approved by the US Food and Drug Administration for the treatment of RA in 1988. Beyond RA and psoriatic arthritis, methotrexate is used in the treatment of systemic lupus erythematosus, idiopathic inflammatory myopathies, and other inflammatory conditions. Methotrexate is cytotoxic to the trophoblast and has been used to treat both ectopic pregnancy and gestational trophoblastic neoplasia, leading to studies in the early 1990s that showed it was effective and safe for early abortion in combination with prostaglandin E1 analog misoprostol. Methotrexate is also a teratogen, causing serious birth defects in 6%-10% of patients taking it while pregnant. Additionally, women are more likely to be affected by both RA at SLE, as compared with males, thus worsening the burden of these adverse effects. Both methotrexate's history of use as an abortifacient and its teratogenic properties make its use more complicated in the current era of abortion policy in the United States following the Dobbs v. Jackson Women's Health Organization ruling. Recently published data suggest that this ruling has affected both provider perspectives and patient experiences as it relates to methotrexate use. In the post-Dobbs era, the role of the rheumatologist as it relates to patients' sexual and reproductive health is likely to expand.

553P Brachio-cervical inflammatory myopathy, an unknown disease with diverse serological and histopathological findings and poor response to treatment

553P Brachio-cervical inflammatory myopathy, an unknown disease with diverse serological and histopathological findings and poor response to treatment

Incidence and outcomes for children with idiopathic inflammatory myopathy in Western Australia-a long-term population-based study.

To determine the incidence and health outcomes for juvenile idiopathic inflammatory myopathy (JIIM) in a long-term whole-population study. We included patients under 18 years hospitalized in Western Australia (WA) from 1985 and 2015 with incident JIIM as defined by pertinent diagnostic codes for dermatomyositis (JDM) polymyositis (JPM), other JIIM and overlap myositis (JOM). We compared clinical outcomes and modified Charlson comorbidity scores with age and gender matched (2:1 ratio) patients with new onset juvenile idiopathic arthritis (JIA). Trends over time for annual incidence rate per million child-population (AIR) were analyzed by least square regression and survival by Kaplan-Meier curves. We included 40 patients with JIIM (63% female, median age 8.5 years) for an average AIR of 2.52 per million (CI 1.09-5.57). AIR was stable over time leading to a point prevalence of 52.61 (CI 40.57-67.06) in 2015. Most patients (80%) were classified as JDM with an AIR for JDM of 2.02 (CI 1.09-5.58) and AIR for the combined other JIIM at 0.51 (CI 0.24-1.15). There was female preponderance (62.5%) in both JIIM groups, but no evidence of seasonality. Over a median follow-up of 13 years, one- and ten-year survival was 94.1%. Compared to JIA patients, readmission (80.4 vs. 63.7, p = .02) and infection rates (15.2 vs. 9.6, p < .01) per 100 person-years were higher for JIIM, with similar frequency of interstitial lung disease, fractures, and thrombotic events. At last observation, nearly all patients in both JIIM cohorts (97.5 vs. 92.5%) had accrued some form of comorbidity. The overall incidence of JIIM leading to hospitalization in WA was stable over 30 years. JIIM prognosis remains suboptimal due to early mortality and accrual of long-term comorbidity.

562P Rare mimics of idiopathic inflammatory myopathies – a single centre cohort from India

562P Rare mimics of idiopathic inflammatory myopathies – a single centre cohort from India

556P Contractile properties of permeabilised single muscle fibres from female patients with idiopathic inflammatory myopathies

556P Contractile properties of permeabilised single muscle fibres from female patients with idiopathic inflammatory myopathies

552P Binding immunoglobulin protein (BiP) abundance and distribution in idiopathic inflammatory myopathies (IIM)

552P Binding immunoglobulin protein (BiP) abundance and distribution in idiopathic inflammatory myopathies (IIM)

576P High precision quantification of ICAM-1 highlights similarities and differences between subgroups of Idiopathic inflammatory myopathies

576P High precision quantification of ICAM-1 highlights similarities and differences between subgroups of Idiopathic inflammatory myopathies

Accurate Visualization of C4d Complement Fragment in Immunohistochemistry by C-Terminal Linear Neoepitope-Specific Antibodies

C4d is the end degradation product of activated complement component C4b that appears during the early steps of the classical and lectin complement pathways. Within the primary sequence of C4d, there is a reactive thioester group that binds covalently to nearby surfaces, thus labeling the locations of complement activation. This feature makes C4d a target for immunohistochemical staining aimed to aid the diagnosis of, among others, the antibody-mediated rejection of transplanted organs, membranous glomerulonephritis, bullous pemphigoid, or inflammatory myopathies. However, the credibility of C4d immunostaining is debatable, as a high background in surrounding tissues and body fluids and diffused patterns of deposits in target structures are experienced with some of the available anti-C4d antibodies. Herein, we present an improved version of a rabbit anti-C4d antibody, originally raised against the C-terminal linear neoepitope of this complement fragment. Minor cross-reactivity with C4b and native C4 proteins, measured by ELISAs, as well as relatively low concentrations necessary for obtaining a specific signal in immunohistochemical analyses of formalin-fixed paraffin-embedded material, makes the improved antibody superior to commercially available rabbit monoclonal anti-C4d antibody SP91 dedicated to ex vivo diagnostics, as demonstrated by the staining of a panel of kidney transplant biopsies.

Comparison of Lineblot and Immunoprecipitation Methods in the Detection of Myositis-Specific and Myositis-Associated Antibodies in Patients with Idiopathic Inflammatory Myopathies: Consistency with Clinical Diagnoses.

Background: the reference method for detection of myositis-specific and myositis-associated antibodies (MSAs and MAAs) is considered immunoprecipitation (IP), but it is routinely replaced by semi-automated methods, like lineblot (LB). Few data are available on the consistency with clinical diagnoses; thus, we aim at analysing these aspects. Methods: sixty-nine patients with idiopathic inflammatory myopathies (IIM) were studied via LB (Myositis Antigens Profile 3 EUROLINE, Euroimmun) and IP (RNA and protein antigens). The degree of concordance between methods was calculated using Cohen's coefficient. Results: a substantial concordance was found for anti-Ku and anti-PM/Scl and a moderate concordance was found for anti-Jo1 and anti-Mi-2, while a fair concordance was found for anti-EJ, anti-SRP, and anti-Ro52 antibodies. The concordance could not be calculated for anti-OJ, anti-PL-7, anti-PL-12, anti-NXP2, anti-TIF1ɣ, and anti-MDA5, because they were only detected with one method. Multiple MSAs were found only with LB in 2/69 sera. Anti-MDA5, TIF1ɣ, NXP2 (detected via IP), and anti-Jo1 in anti-synthetase syndrome (both LB and IP) had the best concordance with clinical diagnosis. Conclusions: LB and IP show substantial concordance for PM/Scl and Ku, and moderate concordance for Jo1 and Mi-2, with a good concordance with clinical diagnoses. IP shows a high performance for DM-associated MSAs. LB seems to be more sensitive in detecting anti-Ro52 antibodies, but it identified multiple MSAs, unlike IP.

The impact of multimorbidity on QoL in inflammatory myopathies: COVAD cluster analysis.

The presence of comorbidities can substantially affect patients' quality of life, but data regarding their impact on idiopathic inflammatory myopathies (IIMs) are limited. We examined the prevalence of comorbidities in IIM patients, other autoimmune rheumatic diseases (oAIRDs), and healthy controls (HCs), using data from the self-reported COVAD-2 survey. We defined Basic Multimorbidity (BM) as the presence of ≥ 2 non-rheumatic chronic conditions and Complex Multimorbidity (CM) as the presence of ≥ 3 non-rheumatic chronic conditions affecting ≥3 organ systems. Hierarchical Clustering on Principal Components was performed for grouping. Among the COVAD respondents, 1558 IIMs, 4591 oAIRDs, and 3652 HCs were analysed. IIMs exhibited a high burden of comorbidities (OR: 1.62 vs oAIRDs and 2.95 vs HCs, p< 0.01), BM (OR 1.66 vs oAIRDs and 3.52 vs HCs, p< 0.01), CM (OR: 1.69 vs AIRDs and 6.23 vs HCs, p< 0.01), and mental health disorders (MHDs) (OR 1.33 vs oAIRDs and 2.63 vs HCs, p< 0.01). Among the IIM patients, those with comorbidities or MHDs had lower PROMIS Global Physical (PGP), PROMIS Global Mental (PGM), and PROMIS Physical Function (SF10) scores, and higher fatigue (F4a) scores (all p< 0.001). PGP, PGM, SF10a and F4a were influenced by age, active disease, BM, and MHDs. Four distinct clusters were identified among the IIMs according to comorbidities and PROMIS scores. Patients with IIMs have a higher burden of comorbidities that influence physical and mental health, identifiable as clinical clusters for optimized and holistic management approaches.

Volumetric muscle composition analysis in sporadic inclusion body myositis using fat-referenced magnetic resonance imaging: Disease pattern, repeatability, and natural progression.

Fat-referenced magnetic resonance imaging (MRI) has emerged as a promising volumetric technique for measuring muscular volume and fat in neuromuscular disorders, but the experience in inflammatory myopathies remains limited. Therefore, this work aimed at describing how sporadic inclusion body myositis (sIBM) manifests on standardized volumetric fat-referenced MRI muscle measurements, including within-scanner repeatability, natural progression rate, and relationship to clinical parameters. Ten sIBM patients underwent whole-leg Dixon MRI at baseline (test-retest) and after 12 months. The lean muscle volume (LMV), muscle fat fraction (MFF), and muscle fat infiltration (MFI) of the quadriceps, hamstrings, adductors, medial gastrocnemius, and tibialis anterior were computed. Clinical assessments of IBM Functional Rating Scale (IBMFRS) and knee extension strength were also performed. The baseline test-retest MRI measurements were used to estimate the within-subject standard deviation (sw). 12-month changes were derived for all parameters. The MRI measurements showed high repeatability in all muscles; sw ranged from 2.7 to 18.0 mL for LMV, 0.7-1.3 percentage points (pp) for MFF, and 0.2-0.7 pp for MFI. Over 12 months, average LMV decreased by 7.4% while MFF and MFI increased by 3.8 pp and 1.8 pp, respectively. Mean IBMFRS decreased by 2.4 and mean knee extension strength decreased by 32.8 N. The MRI measurements showed high repeatability and 12-month changes consistent with muscle atrophy and fat replacement as well as a decrease in both muscle strength and IBMFRS. Our findings suggest that fat-referenced MRI measurements are suitable for assessing disease progression and treatment response in inflammatory myopathies.

Genetic association between TNFA polymorphism rs1799964 with a more severe course of idiopathic inflammatory myopathies

Genetic association between TNFA polymorphism rs1799964 with a more severe course of idiopathic inflammatory myopathies

Peripheral neuroimmunological diseases - Neuropathological insights and clinical perspectives

This article deals with peripheral neuroimmunological diseases and briefly outlines the currently most important aspects and treatment developments. Idiopathic inflammatory myopathies have different mechanisms of development, manifestations and prognoses. New classification systems and more specific treatment concepts have been developed. The IIMs include different subgroups. These entities can have specific autoantibodies. Diagnostically, amuscle biopsy is generally desirable for aprecise diagnosis and is essential in unclear cases. Primary systemic vasculitides can be divided into different groups based on the predominant pattern of involvement, while secondary vasculitides and single organ vasculitides are also differentiated. Vasculitic myopathy cannot be equated with myositis and areliable distinction is currently only possible by a muscle biopsy. Treatment concepts should be developed on an interdisciplinary basis. Chronic inflammatory demyelinating polyneuropathy is the most frequent immune-mediated neuropathy and is characterized by apredominant demyelination of the motor and sensory nerves. The disease course runs in phases or is progressive and leads to significant disability and reduction in quality of life, despite current standard treatment. Novel treatment approaches are currently undergoing clinical trials. Myasthenia gravis, with the leading symptom of exercise-induced muscle weakness, is caused by autoantibodies against structures of the neuromuscular endplate. Autoantibody testing is the most important pillar in the diagnosis and is now also increasingly guiding treatment decisions. Overall, peripheral neuroimmunological diseases represent aheterogeneous group. Increasing knowledge of the pathophysiology is the key to numerous developments in diagnostics and treatment, which could lead to far-reaching practical changes in the future.