Type I interferon-inducible gene expression in blood is present and reflects disease activity in dermatomyositis and polymyositis

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.

Use of Anifrolumab in Systemic Lupus Erythematosus, Cutaneous Lupus Erythematosus, and Other Autoimmune Dermatoses

Anifrolumab is an inhibitor of the type I interferon receptor subunit 1 (IFNAR1) recently approved for the management of moderate-to-severe systemic lupus erythematosus (SLE). In 2 clinical trials, it has proven effective to treat cutaneous signs. Although anifrolumab has not been indicated for cutaneous lupus erythematosus (CLE), multiple cases and case series (20 publications with a total of 78 patients) have shown good and rapid responses with this drug, both in subacute CLE and discoid lupus erythematosus, as well as in lupus panniculitis and perniosis. Two case reports of dermatomyositis have also experienced clinical improvement with anifrolumab. Clinical trials of this drug are ongoing for subacute CLE and discoid lupus erythematosus, systemic sclerosis, and progressive vitiligo. Its most common adverse effects are respiratory infections and herpes zoster. Anifrolumab may be a well-tolerated alternative in the management of CLE.

Novel therapeutic targets in dermatomyositis

Dermatomyositis (DM) is a systemic autoimmune disease with variable clinical presentations, including inflammation in the skin, muscle, lungs, and/or joints. Current therapeutic strategies in DM typically include broad immunosuppression; however, the currently used modalities are not universally effective and are associated with various side effects, including risk of infection. There is currently a highly unmet need for more effective and well-tolerated therapies. Recent years have witnessed increased interest in pharmaceutical development of new therapeutic strategies for DM. This review aims to summarize the landscape of therapies that are currently being tested or planned in patients with DM. These therapies have a wide variety of immunological targets, including T cells, B cells, inflammatory signaling pathways, type I interferons, autoantibodies, and other targets.

A rare case of symptomatic creatine kinase elevation in a patient with rheumatoid arthritis treated with baricitinib

The safety profile of baricitinib (BARI), a Janus kinase inhibitor broadly used for the treatment of rheumatoid arthritis (RA), includes asymptomatic laboratory abnormalities, such as an increase in creatine kinase (CK). Data from randomized controlled trials suggest that concomitant myalgia is rare in RA and does not lead to drug discontinuation. We describe the case of a 68-year-old Caucasian female with longstanding, multi-failure RA who started BARI and achieved disease remission. However, she developed a symptomatic CK increase, as well as a parallel increase in total cholesterol, low-density lipoprotein, and triglycerides. Dechallenge-rechallenge demonstrated a plausible relationship between the clinical/laboratory abnormalities and BARI. In fact, when the drug was withdrawn, CK returned to normal and myalgia disappeared, whereas symptoms returned and CK levels increased when BARI was restarted. BARI may be rarely associated with symptomatic CK elevation, and this may pose clinical challenges, particularly for patients with multi-failure RA who achieved good disease control with BARI but required drug discontinuation due to intolerance.

Interferon Inhibition in SLE: From Bench to Bedside

Despite advances in the management of systemic lupus erythematosus (SLE), it remains a chronic disease with frequent flares, requiring constant medical care, laboratory exams, hospitalisations, and the use of immunosuppressive drugs and corticosteroids, increasing the morbidity and mortality of these patients. The past decade of research has brought to light multiple observations on the role of interferons (IFNs) in the pathogenesis of SLE, which paved the way for the development of potential novel therapies targeting the interferon pathway. Following two phase III trials, anifrolumab, a monoclonal antibody which binds to the type I IFN receptor, blocking the activity of type I IFNs, was approved for active SLE. This review summarises the latest research on the role and mechanisms of type I IFNs in SLE and the development and advances on new therapeutic drugs based on IFN inhibition for SLE.

Type I Interferons in Systemic Autoimmune Rheumatic Diseases: Pathogenesis, Clinical Features and Treatment Options

Type I interferon (IFN) pathway dysregulation plays a crucial role in the pathogenesis of several systemic autoimmune rheumatic diseases (SARDs), including systemic lupus erythematosus (SLE), Sjögren's disease (SjD), systemic sclerosis (SSc), dermatomyositis (DM) and rheumatoid arthritis (RA). Genetic and epigenetic alterations have been involved in dysregulated type I IFN responses in systemic autoimmune disorders. Aberrant type I IFN production and secretion have been associated with distinct clinical phenotypes, disease activity, and severity as well as differentiated treatment responses among SARDs. In this review, we provide an overview of the role of type I IFNs in systemic autoimmune diseases including SLE, RA, SjD, SSc, and DM focusing on pathophysiological, clinical, and therapeutical aspects.

Interferon type I signature associated with skin disease in juvenile dermatomyositis

Background

Interferon type I (IFN-I) signaling system hyperactivation plays an important role in the pathogenesis of juvenile dermatomyositis (JDM).

Aim of the study

To analyze IFN-I score with disease activity in patients with JDM.

Materials and methods

Clinical manifestations laboratory data, and treatment options were analyzed in 15 children with JDM. Disease activity was assessed by CMAS (childhood myositis assessment tool) and CAT (cutaneous assessment tool) scores. IFN I-score was assessed by RT-PCR quantitation of 5 IFN I-regulated transcripts (IFI44L, IFI44, IFIT3, LY6E, MXA1).

Results

All patients had skin and muscle involvement, some had a fever (n = 8), swallowing disorders (n = 4), arthritis (n = 5), calcinosis (n = 3), lipodystrophy (n = 2), and interstitial lung disease (n = 5). Twelve patients had elevated IFN I-score and it was correlated with skin disease activity. Ten patients had clinically active disease and the level of IFN I-score and its components were higher than in patients with inactive disease (8.8 vs. 4.2, p = 0.011). IFN I-score was evaluated in nine patients during follow-up. The simultaneous reduction of IFN I-score and its components, CMAS and CAT scores was observed.

Conclusion

Skin involvement in refractory JDM is a challenging problem requiring the use of additional medications. Serum IFN I-score might be suggested as the promising biomarker of skin disease activity in JDM patients. Further investigations on patients with JDM and recurrent disease activity are needed, especially concerning biomarkers that determine the response to JAK inhibitors and treatment options for patients who don't respond to them.

Extracellular Vesicles in the Pathogenesis, Clinical Characterization, and Management of Dermatomyositis: A Narrative Review

Extracellular vesicles (EVs) are lipid-bilayer particles secreted from cells that primarily assist in cell-to-cell communication through the content of their cargo, such as proteins and RNA. EVs have been implicated in the pathogenesis of various autoimmune diseases, including dermatomyositis (DM), an inflammatory autoimmune disease characterized by distinct cutaneous manifestations, myopathy, and lung disease. We sought to review the role of EVs in DM and understand how they contribute to the pathogenesis and clinical characterization of the disease. We summarized the research progress on EVs in dermatomyositis based on recent publications. EV cargoes, such as double-stranded DNA, microRNA, and proteins, contribute to DM pathogenesis and mediate the proinflammatory response and cytokine release through signaling pathways such as the stimulator of interferon genes (STING) pathway. These nucleic acids and proteins have been proposed as disease-specific, stable biomarkers to monitor disease activity and responses to therapy. They also correlate with clinical parameters, inflammatory markers, and disease severity scores. Furthermore, some markers show an association with morbidities of DM, such as muscle weakness and interstitial lung disease. The continued study of EVs will help us to further elucidate our understanding of dermatomyositis.

Upadacitinib therapy in refractory inflammatory myositis: a case series of 10 patients

OBJECTIVES

To evaluate the effectiveness and safety of upadacitinib in treatment-refractory inflammatory myositis.

METHODS

Patients with refractory inflammatory myositis treated with upadacitinib from a single urban centre in Vancouver, British Columbia, Canada, were included from September 2020 to June 2023. The medical records of these patients were retrospectively reviewed.

RESULTS

10 total patients were identified for review, including 5 classic dermatomyositis (DM), 3 amyopathic DM (ADM) and 2 antisynthetase syndrome. The patients failed an average of four immunosuppressants before initiation of upadacitinib. Three had prior Janus kinase inhibitor therapy with tofacitinib. In the classic DM and ADM aggregate group, upadacitinib offered clinically and statistically significant cutaneous improvement. Lack of active muscle disease at baseline precluded analysis of the effect of upadacitinib on muscle weakness. Nine patients remained on upadacitinib at the end of the study period. One patient discontinued upadacitinib due to severe facial acne.

CONCLUSION

Upadacitinib appears to be effective in targeting cutaneous manifestations of refractory inflammatory DM. Further research is still needed to validate its efficacy on a broader population scale.

Transcriptome analysis of skeletal muscle in dermatomyositis, polymyositis, and dysferlinopathy, using a bioinformatics approach

Background

Polymyositis (PM) and dermatomyositis (DM) are two distinct subgroups of idiopathic inflammatory myopathies. Dysferlinopathy, caused by a dysferlin gene mutation, usually presents in late adolescence with muscle weakness, degenerative muscle changes are often accompanied by inflammatory infiltrates, often resulting in a misdiagnosis as polymyositis.

Objective

To identify differential biological pathways and hub genes related to polymyositis, dermatomyositis and dysferlinopathy using bioinformatics analysis for understanding the pathomechanisms and providing guidance for therapy development.

Methods

We analyzed intramuscular ribonucleic acid (RNA) sequencing data from seven dermatomyositis, eight polymyositis, eight dysferlinopathy and five control subjects. Differentially expressed genes (DEGs) were identified by using DESeq2. Enrichment analyses were performed to understand the functions and enriched pathways of DEGs. A protein-protein interaction (PPI) network was constructed, and clarified the gene cluster using the molecular complex detection tool (MCODE) analysis to identify hub genes.

Results

A total of 1,048, 179 and 3,807 DEGs were detected in DM, PM and dysferlinopathy, respectively. Enrichment analyses revealed that upregulated DEGs were involved in type 1 interferon (IFN1) signaling pathway in DM, antigen processing and presentation of peptide antigen in PM, and cellular response to stimuli in dysferlinopathy. The PPI network and MCODE cluster identified 23 genes related to type 1 interferon signaling pathway in DM, 4 genes (PDIA3, HLA-C, B2M, and TAP1) related to MHC class 1 formation and quality control in PM, and 7 genes (HSPA9, RPTOR, MTOR, LAMTOR1, LAMTOR5, ATP6V0D1, and ATP6V0B) related to cellular response to stress in dysferliniopathy.

Conclusion

Overexpression of genes related to the IFN1 signaling pathway and major histocompatibility complex (MHC) class I formation was identified in DM and PM, respectively. In dysferlinopathy, overexpression of HSPA9 and the mTORC1 signaling pathway genes was detected.

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

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

Systemic Inflammatory Disorders, Immunosuppressive Treatment and Increase Risk of Head and Neck Cancers-A Narrative Review of Potential Physiopathological and Biological Mechanisms

Head and neck cancers (HNCs) are known to present multiple factors likely to influence their development. This review aims to provide a comprehensive overview of the current scientific literature on the interplay between systemic inflammatory disorders, immunosuppressive treatments and their synergistic effect on HNC risk. Both cell-mediated and humoral-mediated systemic inflammatory disorders involve dysregulated immune responses and chronic inflammation and these inflammatory conditions have been associated with an increased risk of HNC development, primarily in the head and neck region. Likewise, the interaction between systemic inflammatory disorders and immunosuppressive treatments appears to amplify the risk of HNC development, as chronic inflammation fosters a tumor-promoting microenvironment, while immunosuppressive therapies further compromise immune surveillance and anti-tumor immune responses. Understanding the molecular and cellular mechanisms underlying this interaction is crucial for developing targeted prevention strategies and therapeutic interventions. Additionally, the emerging field of immunotherapy provides potential avenues for managing HNCs associated with systemic inflammatory disorders, but further research is needed to determine its efficacy and safety in this specific context. Future studies are warranted to elucidate the underlying mechanisms and optimize preventive strategies and therapeutic interventions.

Type I Interferons in Autoimmunity: Implications in Clinical Phenotypes and Treatment Response

Type I interferon (IFN-I) is thought to play a role in many systemic autoimmune diseases. IFN-I pathway activation is associated with pathogenic features, including the presence of autoantibodies and clinical phenotypes such as more severe disease with increased disease activity and damage. We will review the role and potential drivers of IFN-I dysregulation in 5 prototypic autoimmune diseases: systemic lupus erythematosus, dermatomyositis, rheumatoid arthritis, primary Sjögren syndrome, and systemic sclerosis. We will also discuss current therapeutic strategies that directly or indirectly target the IFN-I system.

Transcriptomic profiling and longitudinal study reveal the relationship of anti-MDA5 titer and type I IFN signature in MDA5+ dermatomyositis

Objective

This study aimed to investigate the relationship between anti-MDA5 titer and type I IFN signature in patients with MDA5+ DM.

Methods

We explored the transcriptome profiling of PBMCs in MDA5+ DM patients with high-titer of antibody at disease onset or relapse and normal low-titer after treatment and healthy donors. Subsequently, we revealed the dynamic relationship between serum type I IFN scores and antibody titers.

Result

Differentially expressed genes in MDA5+ DM patients were enriched for related pathways and biological functions linked to viruses and cytokines compared to healthy donors. Similar differences remained pooled between the high-titer and low-titer group, and type I-specific interferon response genes showed upregulation in high-titer group. Significant correlations were found between anti-MDA5 titers and type I IFN scores (r = 0.50, P< 0.001). Contemporaneous anti-MDA5 titers revealed to be significantly higher in the group with ultra-high type I IFN scores (vs. high group, P = 0.027; vs. low group, P< 0.001). Longitudinal assessment of type I IFN scores and anti-MDA5 titers, including pre- and post-treatment changes at initial diagnosis and dynamic changes during treatment, presented an asynchrony between the two parameters in response to treatment.

Conclusion

Anti-MDA5 antibody titers correlated with type I IFN signature in patients with MDA5+ DM and they both changed dynamically but not synchronously over the course of treatment.

2022 EULAR points to consider for the measurement, reporting and application of IFN-I pathway activation assays in clinical research and practice

BACKGROUND

Type I interferons (IFN-Is) play a role in a broad range of rheumatic and musculoskeletal diseases (RMDs), and compelling evidence suggests that their measurement could have clinical value, although testing has not progressed into clinical settings.

OBJECTIVE

To develop evidence-based points to consider (PtC) for the measurement and reporting of IFN-I assays in clinical research and to determine their potential clinical utility.

METHODS

EULAR standardised operating procedures were followed. A task force including rheumatologists, immunologists, translational scientists and a patient partner was formed. Two systematic reviews were conducted to address methodological and clinical questions. PtC were formulated based on the retrieved evidence and expert opinion. Level of evidence and agreement was determined.

RESULTS

Two overarching principles and 11 PtC were defined. The first set (PtC 1-4) concerned terminology, assay characteristics and reporting practices to enable more consistent reporting and facilitate translation and collaborations. The second set (PtC 5-11) addressed clinical applications for diagnosis and outcome assessments, including disease activity, prognosis and prediction of treatment response. The mean level of agreement was generally high, mainly in the first PtC set and for clinical applications in systemic lupus erythematosus. Harmonisation of assay methodology and clinical validation were key points for the research agenda.

CONCLUSIONS

IFN-I assays have a high potential for implementation in the clinical management of RMDs. Uptake of these PtC will facilitate the progress of IFN-I assays into clinical practice and may be also of interest beyond rheumatology.

The Role of Myositis-Specific and Myositis-Associated Autoantibodies and the Activation of Type I Interferon Pathway in the Generation of Clinical Phenotypes of Inflammatory Myopathies

Idiopathic inflammatory myopathies (IIMs) are a group of heterogeneous autoimmune diseases with a prevalence of 20 cases per 100000 of population. Despite their diversity, IMMs are characterised by several common clinical features such as muscle inflammation, proximal muscle weakness, abnormal electromyography and/or muscle biopsy. Over the last years, it has been increasingly recognised that an array of autoantibodies known as myositis-specific antibodies (MSAs) and myositis-associated antibodies (MAAs) are associated with distinct clinical phenotypes and diverse prognosis. Although the exact underlying mechanism of IIMs is not fully understood, accumulating data suggest that the activation of type I interferon pathway plays a central role in disease development. Previous studies have reported the upregulation of type I interferon (IFN) induced genes in peripheral blood and muscle biopsies derived from myositis patients. Given the heterogeneity of inflammatory myopathies along with the central role of type I IFN pathway in disease pathogenesis, the aim of the current study is to elucidate the link between distinct clinical phenotypes of inflammatory myopathies with the presence of serum MSAs or MAAs, as well as with type I IFN activation.

Type 1 interferon signature in peripheral blood mononuclear cells and monocytes of idiopathic inflammatory myopathy patients with different myositis-specific autoantibodies

Background

Myositis-specific autoantibodies (MSAs) are clinically used to diagnose and define idiopathic inflammatory myopathy (IIM) subsets. However, the underlying pathogenic mechanisms of patients with different MSAs remain unclear.

Methods

A total of 158 Chinese patients with IIM and 167 gender- and age-matched healthy controls (HCs) were enrolled. Transcriptome sequencing (RNA-Seq) was performed with peripheral blood mononuclear cells (PBMCs), followed by the identification of differentially expressed genes (DEGs) and analysis of gene set enrichment analysis, immune cell infiltration, and WGCNA. Monocyte subsets and related cytokines/chemokines were quantified. The expressions of interferon (IFN)-related genes were validated using qRT-PCR and Western blot in both PBMCs and monocytes. We also performed correlation analysis and ROC analysis to explore the potential clinical significance of the IFN-related genes.

Results

There were 1,364 genes altered in patients with IIM, including 952 upregulated and 412 downregulated genes. The type I interferon (IFN-I) pathway was remarkably activated in patients with IIM. Compared with patients with other MSAs, IFN-I signatures were significantly activated in patients with anti-melanoma differentiation-associated gene 5 (MDA5) antibodies. In total, 1,288 hub genes associated with IIM onset were identified using WGCNA, including 29 key DEGs associated with IFN signaling. The patients had more CD14brightCD16- classical, CD14brightCD16+ intermediate, and fewer CD14dimCD16+ non-classical monocyte subsets. Plasma cytokines like IL-6 and TNF and chemokines including CCL3 and MCPs increased. The validation of IFN-I-related gene expressions was consistent with the findings from RNA-Seq. The IFN-related genes were correlated with laboratory parameters and helpful for IIM diagnosis.

Conclusion

Gene expressions were remarkably altered in the PBMCs of IIM patients. Anti-MDA5+ IIM patients had a more pronounced activated IFN signature than others. Monocytes exhibited a proinflammatory feature and contributed to the IFN signature of IIM patients.

Type I interferon score is associated with the severity and poor prognosis in anti-MDA5 antibody-positive dermatomyositis patients

Objectives

To investigate the clinical significance of the interferon (IFN) score, especially the IFN-I score, in patients with anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive dermatomyositis (anti-MDA5+ DM).

Methods

We enrolled 262 patients with different autoimmune diseases, including idiopathic inflammatory myopathy, systemic lupus erythematosus, rheumatoid arthritis, adult-onset Still’s disease, and Sjögren’s syndrome, as well as 58 healthy controls. Multiplex quantitative real-time polymerase chain reaction (RT-qPCR) using four TaqMan probes was used to evaluate type I IFN-stimulated genes (IFI44 and MX1), one type II IFN-stimulated gene (IRF1), and one internal control gene (HRPT1), which were used to determine the IFN-I score. The clinical features and disease activity index were compared between the high and low IFN-I score groups in 61 patients with anti-MDA5+ DM. The associations between laboratory findings and the predictive value of the baseline IFN-I score for mortality were analyzed.

Results

The IFN score was significantly higher in patients with anti-MDA5+ DM than in healthy controls. The IFN-I score was positively correlated with the serum IFN-α concentration, ferritin concentration, and Myositis Disease Activity Assessment Visual Analogue Scale (MYOACT) score. Compared with patients with a low IFN-I score, patients with a high IFN-I score showed a higher MYOACT score, C-reactive protein concentration, aspartate transaminase concentration, ferritin concentration, plasma cell percentage, and CD3+ T-cell percentage, as well as lower lymphocyte, natural killer cell, and monocyte counts. The 3-month survival rate was significantly lower in patients with an IFN-I score of &gt;4.9 than in those with an IFN-I score of ≤4.9 (72.9% vs. 100%, respectively; P = 0.044).

Conclusion

The IFN score, especially the IFN-I score, measured by multiplex RT-qPCR is a valuable tool to monitor disease activity and predict mortality in patients with anti-MDA5+ DM.

Type I interferon pathway assays in studies of rheumatic and musculoskeletal diseases: a systematic literature review informing EULAR points to consider

OBJECTIVES

To systematically review the literature for assay methods that aim to evaluate type I interferon (IFN-I) pathway activation and to harmonise-related terminology.

METHODS

Three databases were searched for reports of IFN-I and rheumatic musculoskeletal diseases. Information about the performance metrics of assays measuring IFN-I and measures of truth were extracted and summarised. A EULAR task force panel assessed feasibility and developed consensus terminology.

RESULTS

Of 10 037 abstracts, 276 fulfilled eligibility criteria for data extraction. Some reported more than one technique to measure IFN-I pathway activation. Hence, 276 papers generated data on 412 methods. IFN-I pathway activation was measured using: qPCR (n=121), immunoassays (n=101), microarray (n=69), reporter cell assay (n=38), DNA methylation (n=14), flow cytometry (n=14), cytopathic effect assay (n=11), RNA sequencing (n=9), plaque reduction assay (n=8), Nanostring (n=5), bisulphite sequencing (n=3). Principles of each assay are summarised for content validity. Concurrent validity (correlation with other IFN assays) was presented for n=150/412 assays. Reliability data were variable and provided for 13 assays. Gene expression and immunoassays were considered most feasible. Consensus terminology to define different aspects of IFN-I research and practice was produced.

CONCLUSIONS

Diverse methods have been reported as IFN-I assays and these differ in what elements or aspects of IFN-I pathway activation they measure and how. No 'gold standard' represents the entirety of the IFN pathway, some may not be specific for IFN-I. Data on reliability or comparing assays were limited, and feasibility is a challenge for many assays. Consensus terminology should improve consistency of reporting.

Association between type I interferon pathway activation and clinical outcomes in rheumatic and musculoskeletal diseases: a systematic literature review informing EULAR points to consider

BACKGROUND

Type I interferons (IFN-I) contribute to a broad range of rheumatic and musculoskeletal diseases (RMDs). Compelling evidence suggests that the measurement of IFN-I pathway activation may have clinical value. Although several IFN-I pathway assays have been proposed, the exact clinical applications are unclear. We summarise the evidence on the potential clinical utility of assays measuring IFN-I pathway activation.

METHODS

A systematic literature review was conducted across three databases to evaluate the use of IFN-I assays in diagnosis and monitor disease activity, prognosis, response to treatment and responsiveness to change in several RMDs.

RESULTS

Of 366 screened, 276 studies were selected that reported the use of assays reflecting IFN-I pathway activation for disease diagnosis (n=188), assessment of disease activity (n=122), prognosis (n=20), response to treatment (n=23) and assay responsiveness (n=59). Immunoassays, quantitative PCR (qPCR) and microarrays were reported most frequently, while systemic lupus erythematosus (SLE), rheumatoid arthritis, myositis, systemic sclerosis and primary Sjögren's syndrome were the most studied RMDs. The literature demonstrated significant heterogeneity in techniques, analytical conditions, risk of bias and application in diseases. Inadequate study designs and technical heterogeneity were the main limitations. IFN-I pathway activation was associated with disease activity and flare occurrence in SLE, but their incremental value was uncertain. IFN-I pathway activation may predict response to IFN-I targeting therapies and may predict response to different treatments.

CONCLUSIONS

Evidence indicates potential clinical value of assays measuring IFN-I pathway activation in several RMDs, but assay harmonisation and clinical validation are urged. This review informs the EULAR points to consider for the measurement and reporting of IFN-I pathway assays.

Total glucosides of paeony alleviates scleroderma by inhibiting type I interferon responses

ETHNOPHARMACOLOGICAL RELEVANCE

Type I interferon (IFN) is believed to play a pathogenic role in systemic sclerosis (SSc, also called scleroderma), which is an autoimmune rheumatic disease. Our previous studies have found that Chinese medicine formula Si-Ni-San (SNS, composed of Glycyrrhiza uralensis Fisch., Bupleurum chinense DC., Paeonia lactiflora Pall., and Citrus aurantium L.) had inhibitory effects on type I IFN responses. Among these herbal products, Paeonia lactiflora Pall. has been traditionally used to treat inflammation-related diseases, yet its therapeutic effects against type I IFN-related diseases and potential bioactive ingredients are not characterized.

AIM OF THE STUDY

We aim to identify bioactive ingredient with anti-type I IFN activity from herbal products in SNS and further elucidate its therapeutic effect against scleroderma and underlying mechanisms.

MATERIALS AND METHODS

We constructed a Gaussia-luciferase (Gluc) reporter assay system to identify ingredients with anti-type I IFN activities from SNS. In RAW264.7 cells, real-time PCR (RT-PCR) and western blotting were used to investigate the induction of type I IFN pathway. Additionally, in a bleomycin (BLM)-induced experimental scleroderma model, the expression of fibrotic genes, type I IFN-related genes, inflammatory cytokines, and cytotoxic granules were measured by RT-PCR, and the histopathological changes were determined by H&E staining, Masson's staining and immunohistochemistry analysis.

RESULTS

Our data demonstrated that total glucosides of paeony (TGP) was the bioactive component of SNS that selectively inhibited TLR3-mediated type I IFN responses and blocked type I IFN-induced downstream JAK-STAT signaling pathways. In the BLM-induced scleroderma mouse model, TGP ameliorated skin fibrosis by inhibiting multiple targets in the upstream and downstream of type I IFN signaling. Further research found that TGP hindered polarization of M2 macrophages and their profibrotic effects and reduced cytotoxic T lymphocytes and their cytotoxic granules by suppressing Cxcl9 and Cxcl10 in the skin tissue of scleroderma mice.

CONCLUSIONS

Our study not only sheds novel lights into the immunoregulative effects of TGP but also provides convincing evidence to develop TGP-based therapies in the treatment of scleroderma and other autoimmune diseases associated with type I IFN signatures.

CLASSIFICATION

Skin.

Genetic Influences in Cancer-Associated Myositis

Idiopathic inflammatory myopathies (IIMs) comprise a heterogeneous group of rare immune-mediated disorders that primarily affect muscles but also lead to dysfunction in other organs. Five different clinical subphenotypes of IIM have been distinguished: dermatomyositis, polymyositis, inclusion body myositis, antisynthetase syndrome, and immune-mediated necrotizing myopathy. Excess mortality and morbidity associated with IIM are largely attributed to comorbidities, particularly cancer. The risk of malignancy is not equally distributed among IIM groups and is particularly high among patients with dermatomyositis. The cancer risk peaks around 3 years on either side of the IIM diagnosis and remains elevated even 10 years after the onset of the disease. Lung, colorectal, and ovarian neoplasms typically arise before the onset of IIM, whereas melanoma, cervical, oropharyngeal, and nonmelanoma skin cancers usually develop after IIM diagnosis. Given the close temporal proximity between IIM diagnosis and the emergence of malignancy, it has been proposed that IIM could be a consequence rather than a cause of cancer, a process known as a paramalignant phenomenon. Thus, a separate group of IIMs related to paramalignant phenomenon has been distinguished, known as cancer-associated myositis (CAM). Although the relationship between IIM and cancer is widely recognized, the pathophysiology of CAM remains elusive. Given that genetic factors play a role in the development of IIM, dissection of the molecular mechanisms shared between IIM and cancer presents an opportunity to examine the role of autoimmunity in cancer development and progression. In this review, the evidence supporting the contribution of genetics to CAM will be discussed.

Transcriptome Profiling of Immune Cell Types in Peripheral Blood Reveals Common and Specific Pathways Involved in the Pathogenesis of Myositis-Specific Antibody-Positive Inflammatory Myopathies

OBJECTIVE

Idiopathic inflammatory myopathies (IIM) demonstrate characteristic clinical phenotypes depending on the myositis-specific antibody (MSAs) present. We aimed to identify common or MSA-specific immunological pathways in different immune cell types from peripheral blood by transcriptome analysis.

METHODS

We recruited 33 patients with IIM who were separated into the following groups: 15 patients with active disease at onset and 18 with inactive disease under treatment. All patients were positive for MSAs: anti-melanoma differentiation-associated gene 5 (MDA5) antibody (Ab) in 10 patients, anti-Mi-2 Ab in 7, and anti-aminoacyl-transfer RNA synthetase (ARS) Ab in 16. The patients were compared with 33 healthy controls. Twenty-four immune cell types sorted from peripheral blood were analyzed by flow cytometry, RNA sequencing, and differentially expressed gene analysis combined with pathway analysis.

RESULTS

The frequencies of memory B cell types were significantly decreased in active patients, and the frequency of plasmablasts was prominently increased in active patients with anti-MDA5 Ab in comparison with healthy controls. The expression of type I interferon (IFN)-stimulated genes of all immune cell types was increased in the active, but not inactive, patients. Endoplasmic reticulum stress-related genes in all IIM memory B cells and oxidative phosphorylation-related genes in inactive IIM double negative B cells were also increased, suggesting prominent B cell activation in IIM. Furthermore, active patients with anti-MDA5 Ab, anti-Mi-2 Ab, or anti-ARS Ab were distinguished by IFN-stimulated and oxidative phosphorylation-related gene expression in plasmablasts.

CONCLUSION

Unique gene expression patterns in patients with IIM with different disease activity levels and MSA types suggest different pathophysiologies. Especially, B cells may contribute to common and MSA-specific immunological pathways in IIM.

Efficacy of plasma exchange in patients with anti-MDA5 rapidly progressive interstitial lung disease

BACKGROUND

Rapidly progressive interstitial lung disease (RP-ILD) is a frequent and severe manifestation of anti-MDA5 dermatomyositis (MDA5-DM) associated with poor outcome. The optimal treatment regimen for MDA5-DM RP-ILD is yet to be determined. Specifically, the value of adding plasma exchange (PLEX) to corticosteroids and immunosuppressants remains unclear. We aimed to evaluate the effect of PLEX on the outcome of patients with MDA5-DM RP-ILD.

METHODS

This French nationwide multicentre retrospective study included all MDA5-DM RP-ILD patients from 2012 to 2021 admitted to 18 centres. The primary endpoint was one-year transplant-free survival.

RESULTS

51 patients with MDA5-DM RP-ILD (female 67%; mean age at disease onset: 51 ± 11.6 years) were included. Thirty-two (63%) patients required mechanical ventilation and twenty-five (49%) received PLEX. One-year mortality or lung transplant occurred in 63% cases after a median follow-up of 77 [38-264] days. The Cox proportional hazards multivariable model only retained mechanical ventilation but not PLEX (p = 0.7) as independent predictor of the primary endpoint. One-year transplant-free survival rates in PLEX + vs. PLEX-were 20% vs. 54% (p = 0.01), respectively. The Kaplan-Meier estimated probabilities of one-year transplant-free survival was statistically higher in PLEX-compared to PLEX + patients (p = 0.05). PLEX + compared to PLEX-patients more frequently received mechanical ventilation and immunosuppressants suggesting PLEX + patients had a more severe disease.

CONCLUSION

MDA5-DM RP-ILD is associated with poor rate of one-year transplant-free survival. The use of PLEX was not associated with a better outcome albeit they were mainly given to more severe patients. While our study reports the largest series of MDA5-DM RP-ILD given PLEX, these results needs to be interpreted with caution owing the numerous selection, indication and interpretation bias. Further studies are needed to evaluate their efficacy in this setting.

The potential role of RNA N6-methyladenosine in primary Sjögren's syndrome

Objective

The pathogenesis of primary Sjögren's syndrome (pSS) remains incompletely understood. The N6-methyladenosine (m6A) RNA modification, the most abundant internal transcript modification, has close associations with multiple diseases. This study aimed to investigate the role of m6A in patients with pSS.

Materials and methods

This study enrolled 44 patients with pSS, 50 age- and gender-matched healthy controls (HCs), and 11 age- and gender-matched patients with non-SS sicca. We detected the messenger RNA (mRNA) levels of m6A elements (including METTL3, WTAP, RBM15, ALKBH5, FTO, YTHDF1, YTHDF2, YTHDF3, YTHDC1, and YTHDC2), ISG15, and USP18 in peripheral blood mononuclear cells (PBMCs) from patients with pSS, patients with non-SS sicca, and HCs. The clinical characteristics and laboratory findings of patients with pSS and patients with non-SS sicca were also collected. We used binary logistic regression to determine if m6A elements were risk factors for pSS.

Results

The mRNA levels of m6A writers (METTL3 and RBM15), erasers (ALKBH5 and FTO), and readers (YTHDF1, YTHDF2, YTHDF3, YTHDC1, and YTHDC2) were all significantly higher in PBMCs from patients with pSS than in HCs. The mRNA levels of m6A writers (METTL3 and WTAP) and readers (YTHDF2, YTHDF3, and YTHDC2) were lower in PBMCs from patients with pSS compared to patients with non-SS sicca. The expression of METTL3, RBM15, FTO, YTHDF1, YTHDF2, YTHDC1, and YTHDC2 was positively correlated with the level of C-reactive protein (CRP) of patients with pSS. The mRNA level of YTHDF1 in PBMCs from patients with pSS was negatively correlated with the EULAR Sjögren's syndrome disease activity index (ESSDAI) score. In patients with pSS, FTO, YTHDC1, and YTHDC2 were also related to white blood cells (WBCs), neutrophils, lymphocytes, and monocytes. Increased mRNA level of ALKBH5 in PBMCs was a risk factor for pSS, as determined by binary logistic regression analysis. The mRNA level of ISG15 was positively correlated with that of FTO, YTHDF2, YTHDF3, and YTHDC2 in patients with pSS.

Conclusion

Compared with HCs, the expression of METTL3, RBM15, ALKBH5, FTO, YTHDF1, YTHDF2, YTHDF3, YTHDC1, and YTHDC2 was considerably higher in PBMCs from patients with pSS. In comparison with patients with non-SS sicca, the expression of METTL3, WTAP, YTHDF2, YTHDF3, and YTHDC2 was reduced in PBMCs from patients with pSS. The m6A elements correlating with clinical variables may indicate the disease activity and inflammation status of pSS. Elevated expression of ALKBH5 was a risk factor for pSS. The dynamic process of m6A modification is active in pSS. m6A elements (FTO, YTHDF2, YTHDF3, or YTHDC2) might target ISG15, stimulate the expression of ISG15, and activate the type I IFN signaling pathway, playing an active role in initiating the autoimmunity in pSS.

Blood transcriptomics to facilitate diagnosis and stratification in pediatric rheumatic diseases - a proof of concept study

BACKGROUND

Transcriptome profiling of blood cells is an efficient tool to study the gene expression signatures of rheumatic diseases. This study aims to improve the early diagnosis of pediatric rheumatic diseases by investigating patients' blood gene expression and applying machine learning on the transcriptome data to develop predictive models.

METHODS

RNA sequencing was performed on whole blood collected from children with rheumatic diseases. Random Forest classification models were developed based on the transcriptome data of 48 rheumatic patients, 46 children with viral infection, and 35 controls to classify different disease groups. The performance of these classifiers was evaluated by leave-one-out cross-validation. Analyses of differentially expressed genes (DEG), gene ontology (GO), and interferon-stimulated gene (ISG) score were also conducted.

RESULTS

Our first classifier could differentiate pediatric rheumatic patients from controls and infection cases with high area-under-the-curve (AUC) values (AUC = 0.8 ± 0.1 and 0.7 ± 0.1, respectively). Three other classifiers could distinguish chronic recurrent multifocal osteomyelitis (CRMO), juvenile idiopathic arthritis (JIA), and interferonopathies (IFN) from control and infection cases with AUC ≥ 0.8. DEG and GO analyses reveal that the pathophysiology of CRMO, IFN, and JIA involves innate immune responses including myeloid leukocyte and granulocyte activation, neutrophil activation and degranulation. IFN is specifically mediated by antibacterial and antifungal defense responses, CRMO by cellular response to cytokine, and JIA by cellular response to chemical stimulus. IFN patients particularly had the highest mean ISG score among all disease groups.

CONCLUSION

Our data show that blood transcriptomics combined with machine learning is a promising diagnostic tool for pediatric rheumatic diseases and may assist physicians in making data-driven and patient-specific decisions in clinical practice.

Identification of hub biomarkers and immune cell infiltration characteristics of polymyositis by bioinformatics analysis

Background

Polymyositis (PM) is an acquirable muscle disease with proximal muscle involvement of the extremities as the main manifestation; it is a category of idiopathic inflammatory myopathy. This study aimed to identify the key biomarkers of PM, while elucidating PM-associated immune cell infiltration and immune-related pathways.

Methods

The gene microarray data related to PM were downloaded from the Gene Expression Omnibus database. The analyses using Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes, gene set enrichment analysis (GSEA), and protein-protein interaction (PPI) networks were performed on differentially expressed genes (DEGs). The hub genes of PM were identified using weighted gene co-expression network analysis (WGCNA) and least absolute shrinkage and selection operator (LASSO) algorithm, and the diagnostic accuracy of hub markers for PM was assessed using the receiver operating characteristic curve. In addition, the level of infiltration of 28 immune cells in PM and their interrelationship with hub genes were analyzed using single-sample GSEA.

Results

A total of 420 DEGs were identified. The biological functions and signaling pathways closely associated with PM were inflammatory and immune processes. A series of four expression modules were obtained by WGCNA analysis, with the turquoise module having the highest correlation with PM; 196 crossover genes were obtained by combining DEGs. Subsequently, six hub genes were finally identified as the potential biomarkers of PM using LASSO algorithm and validation set verification analysis. In the immune cell infiltration analysis, the infiltration of T lymphocytes and subpopulations, dendritic cells, macrophages, and natural killer cells was more significant in the PM.

Conclusion

We identified the hub genes closely related to PM using WGCNA combined with LASSO algorithm, which helped clarify the molecular mechanism of PM development and might have great significance for finding new immunotherapeutic targets, and disease prevention and treatment.

Activation of cGAS‐STING pathway – A possible cause of myofiber atrophy/necrosis in dermatomyositis and immune‐mediated necrotizing myopathy

Objective

The objective was to investigate the expression of the cGAS‐STING pathway‐associated protein in idiopathic inflammatory myopathy (IIM) and to investigate whether it is related to myofiber atrophy/necrosis in patients with dermatomyositis and immune‐mediated necrotizing myopathy.

Material and Methods

Muscle specimens obtained by open biopsy from 26 IIM patients (14 with dermatomyositis (DM), 8 with immune‐mediated necrotizing myopathy (IMNM), and 4 with other types of IIM), 4 dystrophinopathy, and 9 control patients were assessed for expression of cGAS‐STING pathway members via Western blot, quantitative real‐time PCR analysis (qRT‐PCR), and immunochemistry. Meanwhile, analysis its location distribution througn immunochemistry.

Results

Compared to the control group, the expression of cGAS, STING, and related molecules was obviously increased in muscle samples of IIM patients. Upregulated cGAS and STING were mainly located in the vascular structure, inflammatory infiltrates, and atrophic and necrotic fibers. While comparing to the Dys patients, the mRNA level of cGAS, STING, and TNF‐a was upregulated, meanwhile, the protein of the TBK1, P‐TBK1, and P‐IRF3 associated with interferon upregulation was overexpressed through Western blot in IMNM and DM. Considering that cGAS and STING are located in necrotic and Mx1‐positive atrophic fibers, it is really possible that the cGAS‐STING pathway may lead to fibers atrophy/necrosis by producing IFNs.

Conclusion

The cGAS‐STING pathway was activated in the muscle samples of IIM patients and its activation may be the reason of myofiber atrophy and necrosis in DM and IMNM patients.

Anti-MDA5 Antibody Linking COVID-19, Type I Interferon, and Autoimmunity: A Case Report and Systematic Literature Review

Introduction

The SARS-CoV-2 infection has been advocated as an environmental trigger for autoimmune diseases, and a paradigmatic example comes from similarities between COVID-19 and the myositis-spectrum disease associated with antibodies against the melanoma differentiation antigen 5 (MDA5) in terms of clinical features, lung involvement, and immune mechanisms, particularly type I interferons (IFN).

Case Report

We report a case of anti-MDA5 syndrome with skin manifestations, constitutional symptoms, and cardiomyopathy following a proven SARS-CoV-2 infection.

Systematic Literature Review

We systematically searched for publications on inflammatory myositis associated with COVID-19. We describe the main clinical, immunological, and demographic features, focusing our attention on the anti-MDA5 syndrome.

Discussion

MDA5 is a pattern recognition receptor essential in the immune response against viruses and this may contribute to explain the production of anti-MDA5 antibodies in some SARS-CoV-2 infected patients. The activation of MDA5 induces the synthesis of type I IFN with an antiviral role, inversely correlated with COVID-19 severity. Conversely, elevated type I IFN levels correlate with disease activity in anti-MDA5 syndrome. While recognizing this ia broad area of uncertainty, we speculate that the strong type I IFN response observed in patients with anti-MDA5 syndrome, might harbor protective effects against viral infections, including COVID-19.

Refractory alopecia universalis associated with dermatomyositis successfully treated with tofacitinib

Dermatomyositis (DM) and alopecia areata are two diseases characterised by aberrant interferon signalling. While patchy alopecia of the scalp is a known feature of DM, alopecia universalis, which involves hair loss over the entire body, has rarely been reported in conjunction with DM. Herein, we report the case of a 30-year-old female with DM who developed refractory cutaneous disease and alopecia universalis that were successfully treated with tofacitinib. This could suggest that concomitant severe alopecia and refractory cutaneous DM may reflect a strong baseline interferon gene signature that may predict responsiveness to janus kinase inhibitors.

Current and new targets for treating myositis

As treatment of refractory idiopathic inflammatory myopathies (IIM) has been challenging, there is growing interest in assessing new therapies that target various pathways implicated in the pathogenesis of IIM. In the largest clinical trial to date, rituximab was studied in adult and juvenile myositis, but the primary outcome was not met despite 83 percent of subjects with refractory myositis meeting the definition of improvement. The U.S. Food and Drug Administration (FDA) has recently granted approval to Octagam 10% immune globulin intravenous (IVIg), for the treatment of adult dermatomyositis based on impressive results from a double-blind placebo-controlled trial. Anti-tumor necrosis factor (anti-TNF) utility in IIM is not recommended and recent reports suggest this therapy may induce systemic autoimmune disease including myositis. Further, anti-IL6 therapy cannot be recommended as a recent trial of tocilizumab failed to reach its primary endpoint. Further studies are needed to assess the role of newer therapies such as abatacept (inhibition of T cell co-stimulation), sifalimumab (anti-IFNα), Janus kinase [JAK] inhibitors, apremilast (phosphodiesterase 4 inhibitor), and KZR-616 (selective inhibitor of the immunoproteasome) given their biological plausibility and encouraging recent small-case series results. The future of IIM therapy will depend on exploring biomarkers implicated in the etiopathogenesis of IIM, improvements in myositis classification based on serological and histopathological features, and well-designed controlled clinical trials using validated consensus outcome measures.

Update on Biomarkers of Vasculopathy in Juvenile and Adult Myositis

PURPOSE OF REVIEW

Although rare, idiopathic inflammatory myopathies (IIM) comprise a heterogeneous group of autoimmune conditions in adults and children. Increasingly, vasculopathy is recognised to be key in the underlying pathophysiology and plays a crucial role in some of the more challenging complications including calcinosis, gastrointestinal involvement and interstitial lung disease. The exciting prospect of development of biomarkers of vasculopathy would enable earlier detection and monitoring of these complications and possible prevention of their potentially devastating consequences. The purpose was to review the current literature on biomarkers of vasculopathy in IIM and offer insight as to the biomarkers most likely to have an impact on clinical care.

RECENT FINDINGS

Multiple candidate biomarkers have been studied including circulating endothelial cells (CEC), microparticles (MP), soluble adhesion markers (ICAM-1, ICAM-3, VCAM-1), selectin proteins (E-, L-, P-selectin), coagulation factors, angiogenic factors, cytokines (including (IL-6, IL-10, TNF-α, IL-18) and interferon (IFN)-related biomarkers (including IFNα, IFN-β, IFNγ, galectin-9, interferon signature and interferon-related chemokines (MCP-1, IP-10 and MIG). There is a growing body of evidence of the potential role of biomarkers in detecting and monitoring the vasculopathy in IIM, detecting disease activity and predicting disease flares and overall prognosis. Exciting progress has been made in the search for biomarkers of vasculopathy of IIM; however, none of the studies are validated and further research is required.

Identification of hub biomarkers and immune cell infiltration in polymyositis and dermatomyositis

Objective: Polymyositis (PM) and dermatomyositis (DM) are heterogeneous disorders. However, the etiology of PM/DM development has not been thoroughly clarified.

Methods: Gene expression data of PM/DM were obtained from Gene Expression Omnibus. We used robust rank aggregation (RRA) to identify differentially expressed genes (DEGs). Gene Ontology functional enrichment and pathway analyses were used to investigate potential functions of the DEGs. Weighted gene co-expression network analysis (WGCNA) was used to establish a gene co-expression network. CIBERSORT was utilized to analyze the pattern of immune cell infiltration in PM/DM. Protein–protein interaction (PPI) network, Venn, and association analyses between core genes and muscle injury were performed to identify hub genes. Receiver operating characteristic analyses were executed to investigate the value of hub genes in the diagnosis of PM/DM, and the results were verified using the microarray dataset GSE48280.

Results: Five datasets were included. The RRA integrated analysis identified 82 significant DEGs. Functional enrichment analysis revealed that immune function and the interferon signaling pathway were enriched in PM/DM. WGCNA outcomes identified MEblue and MEturquoise as key target modules in PM/DM. Immune cell infiltration analysis revealed greater macrophage infiltration and lower regulatory T-cell infiltration in PM/DM patients than in healthy controls. PPI network, Venn, and association analyses of muscle injury identified five putative hub genes: TRIM22, IFI6, IFITM1, IFI35, and IRF9.

Conclusions: Our bioinformatics analysis identified new genetic biomarkers of the pathogenesis of PM/DM. We demonstrated that immune cell infiltration plays a pivotal part in the occurrence of PM/DM.

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.

Antibody Therapies in Autoimmune Inflammatory Myopathies: Promising Treatment Options

Inflammatory myopathies, including polymyositis (PM), dermatomyositis (DM), inclusion body myositis (IBM), necrotizing myopathy (NM), antisynthetase syndrome (ASS) and overlap myositis (OM), in short myositis, are rare diseases. All forms of myositis have progressive muscle weakness in common, with each subtype characterized by different autoantibody profiles, histological findings and extramuscular manifestations. Due to better understanding of the pathogenesis of the muscle inflammation in myositis, new molecular pathways for targeted therapy have been discovered. Current therapies aim at different components of the innate or the adaptive immune response. Additionally, non-inflammatory mechanisms in myositis have come into focus as possible treatment targets. The use of therapeutical antibodies in myositis has been examined in various clinical studies, several of them randomized controlled ones: Depletion of B-cells by rituximab has been established as treatment of refractory myositis. IVIG, an antibody therapy in the wider sense, has now been licensed for DM following a recent positive clinical trial. Negative study results were reported in randomized trials with infliximab, sifalimumab and bimagrumab. Studies on basiliximab and eculizumab are currently underway, and are expected to yield results in a couple of years. Despite some promising results of clinical studies with antibody therapy in myositis, further research is crucial to optimize the treatment for this debilitating disease and to find treatment alternatives for treatment-refractory patients.

Interferon-β acts directly on T cells to prolong allograft survival by enhancing regulatory T cell induction through Foxp3 acetylation

Type I interferons (IFNs) are pleiotropic cytokines with potent antiviral properties that also promote protective T cell and humoral immunity. Paradoxically, type I IFNs, including the widely expressed IFNβ, also have immunosuppressive properties, including promoting persistent viral infections and treating T-cell-driven, remitting-relapsing multiple sclerosis. Although associative evidence suggests that IFNβ mediates these immunosuppressive effects by impacting regulatory T (Treg) cells, mechanistic links remain elusive. Here, we found that IFNβ enhanced graft survival in a Treg-cell-dependent murine transplant model. Genetic conditional deletion models revealed that the extended allograft survival was Treg cell-mediated and required IFNβ signaling on T cells. Using an in silico computational model and analysis of human immune cells, we found that IFNβ directly promoted Treg cell induction via STAT1- and P300-dependent Foxp3 acetylation. These findings identify a mechanistic connection between the immunosuppressive effects of IFNβ and Treg cells, with therapeutic implications for transplantation, autoimmunity, and malignancy.

Type I Interferons in Autoimmunity

Dysregulated IFN-1 responses play crucial roles in the development of multiple forms of autoimmunity. Many patients with lupus, systemic sclerosis, Sjogren's syndrome, and dermatomyositis demonstrate enhanced IFN-1 signaling. IFN-1 excess is associated with disease severity and autoantibodies and could potentially predict response to newer therapies targeting IFN-1 pathways. In this review, we provide an overview of the signaling pathway and immune functions of IFN-1s in health and disease. We also review the systemic autoimmune diseases classically associated with IFN-1 upregulation and current therapeutic strategies targeting the IFN-1 system.

SIGLEC1 enables straightforward assessment of type I interferon activity in idiopathic inflammatory myopathies

Objective

To evaluate sialic acid binding Ig-like lectin 1 (SIGLEC1) expression on monocytes by flow cytometry as a type I interferon biomarker in idiopathic inflammatory myopathies (IIM).

Methods

We performed a retrospective analysis of adult and paediatric patients with the diagnosis of IIM. SIGLEC1 expression was assessed by flow cytometry and was compared with Physician Global Assessment or Childhood Myositis Assessment Scale disease activity scores. Mann Whitney U test and receiver operating characteristic curves were used for cross-sectional data analysis (n=96), two-level mixed-effects linear regression model for longitudinal analyses (n=26, 110 visits). Response to treatment was analysed in 14 patients within 12 months, using Wilcoxon test. SIGLEC1 was compared with interferon-stimulated gene 15/MxA status by immunohistochemical staining of muscle biopsies (n=17).

Results

96 patients with adult (a) and juvenile (j) dermatomyositis (DM, n=38), antisynthetase syndrome (AS, n=19), immune-mediated necrotising myopathy (IMNM, n=8), inclusion body myositis (IBM, n=9) and overlap myositis (n=22) were included. SIGLEC1 distinguished significantly between active and inactive disease with an area under the curve of 0.92 (95% CI 0.83 to 1) in DM and correlated with disease activity longitudinally (aDM: standardised beta=0.54, p<0.001; jDM: standardised beta=−0.70, p<0.001). Response to treatment in DM was associated with a decreasing SIGLEC1 (p<0.01, Wilcoxon test). SIGLEC1 was found upregulated in 8 of 19 patients with AS, 2 of 9 patients with IBM but not in IMNM.

Conclusion

SIGLEC1 is a candidate biomarker to assess type I interferon activity in IIM and proved useful for monitoring disease activity and response to treatment in juvenile and adult DM.

COVID-19 Disease and Dermatomyositis: A Mini-Review

The pandemic of coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 has caused a large number of deaths, and there is still no effective treatment. COVID-19 can induce a systemic inflammatory response, and its clinical manifestations are diverse. Recently, it has been reported that COVID-19 patients may develop myositis and interstitial pulmonary disease similar to dermatomyositis (DM). This condition is similar to the rapidly progressive interstitial lung disease associated with MDA5+ DM that has a poor prognosis and high mortality, and this poses a challenge for an early identification. Suppression of the immune system can protect COVID-19 patients by preventing the production of inflammatory cytokines. This article attempts to explore the possibility of a relationship between COVID-19 and DM in terms of the potential pathogenesis and clinical features and to analyze the therapeutic effect of the immunosuppressive drugs that are commonly used for the treatment of both DM and COVID-19.

Idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIM), also known as myositis, are a heterogeneous group of autoimmune disorders with varying clinical manifestations, treatment responses and prognoses. Muscle weakness is usually the classical clinical manifestation but other organs can be affected, including the skin, joints, lungs, heart and gastrointestinal tract, and they can even result in the predominant manifestations, supporting that these are systemic inflammatory disorders. Different myositis-specific autoantibodies have been identified and, on the basis of clinical, histopathological and serological features, IIMs can be classified into several subgroups — dermatomyositis (including amyopathic dermatomyositis), antisynthetase syndrome, immune-mediated necrotizing myopathy, inclusion body myositis, polymyositis and overlap myositis. The prognoses, treatment responses and organ manifestations vary among these groups, implicating different pathophysiological mechanisms in each subtype. A deeper understanding of the molecular pathways underlying the pathogenesis and identifying the autoantigens of the immune reactions in these subgroups is crucial to improve outcomes. New, more homogeneous subgroups defined by autoantibodies may help define disease mechanisms, and will also be important in future clinical trials to develop targeted therapies and in identifying biomarkers to guide treatment decisions for the individual patient.

Idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIM), also known as myositis, are a heterogeneous group of autoimmune disorders with varying clinical manifestations, treatment responses and prognoses. Muscle weakness is usually the classical clinical manifestation but other organs can be affected, including the skin, joints, lungs, heart and gastrointestinal tract, and they can even result in the predominant manifestations, supporting that IIM are systemic inflammatory disorders. Different myositis-specific auto-antibodies have been identified and, on the basis of clinical, histopathological and serological features, IIM can be classified into several subgroups - dermatomyositis (including amyopathic dermatomyositis), antisynthetase syndrome, immune-mediated necrotizing myopathy, inclusion body myositis, polymyositis and overlap myositis. The prognoses, treatment responses and organ manifestations vary among these groups, implicating different pathophysiological mechanisms in each subtype. A deeper understanding of the molecular pathways underlying the pathogenesis and identifying the auto-antigens of the immune reactions in these subgroups is crucial to improving outcomes. New, more homogeneous subgroups defined by auto-antibodies may help define disease mechanisms and will also be important in future clinical trials for the development of targeted therapies and in identifying biomarkers to guide treatment decisions for the individual patient.

Muscle transcriptome provides the first insight into the dynamics of gene expression with progression of age in sheep

The dynamic synergy of genes and pathways in muscles in relation to age affects the muscle characteristics. Investigating the temporal changes in gene expression will help illustrate the molecular mechanisms underlying muscle development. Here we report the gene expression changes in skeletal muscles through successive age groups in Bandur, a meat type sheep of India. RNA sequencing data was generated from the longissimus thoracis muscles from four age groups, ranging from lamb to adult. Analysis of 20 highest expressed genes common across the groups revealed muscle protein, phosphorylation, acetylation, metal binding and transport as significant functions. Maximum differentiation was observed after 2.5–3 years on transition from lambs to adult. Transcriptional regulation by the TFAP2 transcription factors, IL-6 signaling and PI3K/AKT signaling pathways were enriched in younger animals. The gene-protein network demarcated key interactive genes involved in muscle development and proliferation that can be used as candidates for future research on improvement of muscle characteristics.

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.

Clinical and laboratory parameters predicting cancer in dermatomyositis patients with anti-TIF1γ antibodies

BACKGROUND

Dermatomyositis (DM) is a chronic acquired autoimmune disorder strongly associated with cancer development. Until now, identifying predictive markers indicating a high risk of cancer has challenged clinicians. Although anti-TIF1γ antibody is a major serological indicator for cancer-associated DM, many anti-TIF1γ antibody-positive DM patients lack malignancy.

OBJECTIVES

To determine clinical and laboratory parameters that support cancer prediction in anti-TIF1γ antibody-positive DM patients.

METHODS

Clinical and laboratory data were collected from cancer-associated and unassociated DM patients with anti-TIF1γ antibodies. Serum cytokine concentrations were measured with a cytokine array assay. The values of inflammatory cytokines in cancer prognosis were determined with a receiver operating characteristic curve analysis.

RESULTS

The cancer group had a significantly higher frequency of males, older mean age and higher anti-TIF1γ antibody levels. Some inflammatory cytokines, particularly tumour necrosis factor (TNF) and TNF receptor superfamilies, had increased levels in sera that were correlated with myositis markers, cutaneous severity and DM disease activity. Moreover, these cytokines had an area under the curve (AUC) ≥0.8 and high sensitivity and specificity at their specific cut-off, even higher than anti-TIF1γ levels in cancer prediction in our DM patients.

CONCLUSIONS

Our results suggest a close pathophysiological relationship among myositis, cancer and skin involvements in DM patients with anti-TIF1γ antibodies and the potential clinical significance of anti-TIF1γ antibody levels in evaluating disease severity and prognosis in DM patients. Some inflammatory cytokines, particularly TNF and TNF receptor superfamilies including BAFF, sTNF-R1 and sTNF-R2, may support cancer prediction in DM patients with anti-TIF1γ antibodies.

UMP-CMP kinase 2 gene expression in macrophages is dependent on the IRF3-IFNAR signaling axis

Toll-like receptors (TLRs) are highly-conserved pattern recognition receptors that mediate innate immune responses to invading pathogens and endogenous danger signals released from damaged and dying cells. Activation of TLRs trigger downstream signaling cascades, that culminate in the activation of interferon regulatory factors (IRFs), which subsequently leads to type I interferon (IFN) response. In the current study, we sought to expand the scope of gene expression changes in THP1-derived macrophages upon TLR4 activation and to identify interferon-stimulated genes. RNA-seq analysis led to the identification of several known and novel differentially expressed genes, including CMPK2, particularly in association with type I IFN signaling. We performed an in-depth characterization of CMPK2 expression, a nucleoside monophosphate kinase that supplies intracellular UTP/CTP for nucleic acid synthesis in response to type I IFN signaling in macrophages. CMPK2 was significantly induced at both RNA and protein levels upon stimulation with TLR4 ligand-LPS and TLR3 ligand-Poly (I:C). Confocal microscopy and subcellular fractionation indicated CMPK2 localization in both cytoplasm and mitochondria of THP-1 macrophages. Furthermore, neutralizing antibody-based inhibition of IFNAR receptor in THP-1 cells and BMDMs derived from IFNAR KO and IRF3 KO knockout mice further revealed that CMPK2 expression is dependent on LPS/Poly (I:C) mediated IRF3- type I interferon signaling. In summary, our findings suggest that CMPK2 is a potential interferon-stimulated gene in THP-1 macrophages and that CMPK2 may facilitate IRF3- type I IFN-dependent anti-bacterial and anti-viral roles.

Inherited Autoinflammatory Syndromes

Autoinflammation describes a collection of diverse diseases caused by indiscriminate activation of the immune system in an antigen-independent manner. The rapid advancement of genetic diagnostics has allowed for the identification of a wide array of monogenic causes of autoinflammation. While the clinical picture of these syndromes is diverse, it is possible to thematically group many of these diseases under broad categories that provide insight into the mechanisms of disease and therapeutic possibilities. This review covers archetypical examples of inherited autoinflammatory diseases in five major categories: inflammasomopathy, interferonopathy, unfolded protein/cellular stress response, relopathy, and uncategorized. This framework can suggest where future work is needed to identify other genetic causes of autoinflammation, what types of diagnostics need to be developed to care for this patient population, and which options might be considered for novel therapeutic targeting. Expected final online publication date for the Annual Review of Pathology: Mechanisms of Disease, Volume 17 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

JAK inhibitors: a potential treatment for JDM in the context of the role of interferon-driven pathology

Juvenile Idiopathic Inflammatory Myopathies (IIM) are a group of rare diseases that are heterogeneous in terms of pathology that can include proximal muscle weakness, associated skin changes and systemic involvement. Despite options for treatment, many patients continue to suffer resistant disease and lasting side-effects. Advances in the understanding of the immunopathology and genetics underlying IIM may specify new therapeutic targets, particularly where conventional treatment has not achieved a clinical response. An upregulated type I interferon signature is strongly associated with disease and could be a prime target for developing more specific therapeutics. There are multiple components of the IFN pathway that could be targeted for blockade therapy.Downstream of the cytokine receptor complexes are the Janus kinase-signal transducers and activators of transcription (JAK-STAT) pathway, which consists of JAK1-3, TYK2, and STAT1-6. Therapeutic inhibitors have been developed to target components of this pathway. Promising results have been observed in case studies reporting the use of the JAK inhibitors, Baricitinib, Tofacitinib and Ruxolitinib in the treatment of refractory Juvenile Dermatomyositis (JDM). There is still the question of safety and efficacy for the use of JAK inhibitors in JDM that need to be addressed by clinical trials. Here we review the future for the use of JAK inhibitors as a treatment for JDM.

Type I interferon detection in autoimmune diseases: challenges and clinical applications

INTRODUCTION

Accumulating data highlights that the dysregulation of type I interferon (IFN) pathways plays a central role in the pathogenesis of several systemic and organ-specific autoimmune diseases. Advances in understanding the role of type I IFNs in these disorders can lead to targeted drug development as well as establishing potential disease biomarkers.

AREAS COVERED

Here, we summarize current knowledge regarding the role of type I IFNs in the major systemic, as well as organ-specific, autoimmune disorders, including prominent inflammatory CNS disorders like multiple sclerosis.

EXPERT OPINION

Type I IFN involvement and its clinical associations in a wide spectrum of autoimmune diseases represents a promising area for research aiming to unveil common pathogenetic pathways in systemic and organ-specific autoimmunity.