Innate immune-response mechanisms in dermatomyositis: an update on pathogenesis, diagnosis and treatment

Inflammasomes and idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIM) are a group of systemic autoimmune diseases characterized by muscle weakness and elevated serum creatine kinase levels. Recent research has highlighted the role of the innate immune system, particularly inflammasomes, in the pathogenesis of IIM. This review focuses on the role of inflammasomes, specifically NLRP3 and AIM2, and their associated proteins in the development of IIM. We discuss the molecular mechanisms of pyroptosis, a programmed cell death pathway that triggers inflammation, and its association with IIM. The NLRP3 inflammasome, in particular, has been implicated in muscle fiber necrosis and the subsequent release of damage-associated molecular patterns (DAMPs), leading to inflammation. We also explore the potential therapeutic implications of targeting the NLRP3 inflammasome with inhibitors such as glyburide and MCC950, which have shown promise in reducing inflammation and improving muscle function in preclinical models. Additionally, we discuss the role of caspases, particularly caspase-1, in the canonical pyroptotic pathway associated with IIM. The understanding of these mechanisms offers new avenues for therapeutic intervention and a better comprehension of IIM pathophysiology.

Macrophage involvement in idiopathic inflammatory myopathy: pathogenic mechanisms and therapeutic prospects

Idiopathic inflammatory myopathies are a group of systemic autoimmune diseases characterized by chronic muscle inflammation and diverse clinical manifestations. Macrophages, pivotal components of innate immunity, are implicated in immune responses, inflammation resolution, and tissue repair. Distinct macrophage polarization states play vital roles in disease progression and resolution. Mechanistically, activated macrophages release proinflammatory cytokines, chemokines, and reactive oxygen species, perpetuating immune responses and tissue damage. Dysregulated macrophage polarization contributes to sustained inflammation. Here, we reviewed the intricate contributions of macrophages to IIM pathogenesis and explored novel therapeutic avenues. We discussed emerging strategies targeting macrophages, including receptor-based interventions and macrophage polarization modulation, for IIM treatment. This review underscores the multifaceted involvement of macrophages in IIM pathogenesis and offers insights into potential therapeutic approaches targeting these immune cells for disease management.

Identification and validation of interferon-stimulated gene 15 as a biomarker for dermatomyositis by integrated bioinformatics analysis and machine learning

Background

Dermatomyositis (DM) is an autoimmune disease that primarily affects the skin and muscles. It can lead to increased mortality, particularly when patients develop associated malignancies or experience fatal complications such as pulmonary fibrosis. Identifying reliable biomarkers is essential for the early diagnosis and treatment of DM. This study aims to identify and validate pivotal diagnostic biomarker for DM through integrated bioinformatics analysis and clinical sample validation.

Methods

Gene expression datasets GSE46239 and GSE142807 from the Gene Expression Omnibus (GEO) database were merged for analysis. Differentially expressed genes (DEGs) were identified and subjected to enrichment analysis. Advanced machine learning methods were utilized to further pinpoint hub genes. Weighted gene co-expression network analysis (WGCNA) was also conducted to discover key gene modules. Subsequently, we derived intersection gene from these methods. The diagnostic performance of the candidate biomarker was evaluated using analysis with dataset GSE128314 and confirmed by immunohistochemistry (IHC) in skin lesion biopsy specimens. The CIBERSORT algorithm was used to analyze immune cell infiltration patterns in DM, then the association between the hub gene and immune cells was investigated. Gene set enrichment analysis (GSEA) was performed to understand the biomarker's biological functions. Finally, the drug-gene interactions were predicted using the DrugRep server.

Results

Interferon-stimulated gene 15 (ISG15) was identified by intersecting DEGs, advanced machine learning-selected genes and key module genes from WGCNA. ROC analysis showed ISG15 had a high Area under the curve (AUC) of 0.950. IHC findings confirmed uniformly positive expression of ISG15, particularly in perivascular regions and lymphocytes, contrasting with universally negative expression in controls. Further analysis revealed that ISG15 is involved in abnormalities in various immune cells and inflammation-related pathways. We also predicted three drugs targeting ISG15, supported by molecular docking studies.

Conclusion

Our study identifies ISG15 as a highly specific diagnostic biomarker for DM, ISG15 may be closely related to the pathogenesis of DM, demonstrating promising potential for clinical application.

Novel endotypes of antisynthetase syndrome identified independent of anti-aminoacyl transfer RNA synthetase antibody specificity that improve prognostic stratification

OBJECTIVES

To systemically analyse the heterogeneity in the clinical manifestations and prognoses of patients with antisynthetase syndrome (ASS) and evaluate the transcriptional signatures related to different clinical phenotypes.

METHODS

A total of 701 patients with ASS were retrospectively enrolled. The clinical presentation and prognosis were assessed in association with four anti-aminoacyl transfer RNA synthetase (ARS) antibodies: anti-Jo1, anti-PL7, anti-PL12 and anti-EJ. Unsupervised machine learning was performed for patient clustering independent of anti-ARS antibodies. Transcriptome sequencing was conducted in clustered ASS patients and healthy controls.

RESULTS

Patients with four different anti-ARS antibody subtypes demonstrated no significant differences in the incidence of rapidly progressive interstitial lung disease (RP-ILD) or prognoses. Unsupervised machine learning, independent of anti-ARS specificity, identified three endotypes with distinct clinical features and outcomes. Endotype 1 (RP-ILD cluster, 23.7%) was characterised by a high incidence of RP-ILD and a high mortality rate. Endotype 2 (dermatomyositis (DM)-like cluster, 14.5%) corresponded to patients with DM-like skin and muscle symptoms with an intermediate prognosis. Endotype 3 (arthritis cluster, 61.8%) was characterised by arthritis and mechanic's hands, with a good prognosis. Transcriptome sequencing revealed that the different endotypes had distinct gene signatures and biological processes.

CONCLUSIONS

Anti-ARS antibodies were not significant in stratifying ASS patients into subgroups with greater homogeneity in RP-ILD and prognoses. Novel ASS endotypes were identified independent of anti-ARS specificity and differed in clinical outcomes and transcriptional signatures, providing new insights into the pathogenesis of ASS.

The role and application of three IFN-related reactions in psoriasis

The pathophysiology of psoriasis is a highly complicated one. Due to the disease's specificity, it not only affects the patient's skin negatively but also manifests systemic pathological changes. These clinical symptoms seriously harm the patient's physical and mental health. IFN, a common immunomodulatory factor, has been increasingly demonstrated to have a significant role in the development of psoriatic skin disease. Psoriasis is connected with a variety of immunological responses. New targets for the therapy of autoimmune skin diseases may emerge from further research on the mechanics of the associated IFN upstream and downstream pathways. Different forms of IFNs do not behave in the same manner in psoriasis, and understanding how different types of IFNs are involved in psoriasis may provide a better notion for future research. This review focuses on the involvement of three types of IFNs in psoriasis and related therapeutic investigations, briefly describing the three IFNs' production and signaling, as well as the dual effects of IFNs on the skin. It is intended that it would serve as a model for future research.

Cytotoxic dermatitis: Review of the interface dermatitis pattern in veterinary skin diseases

Interface dermatitis or lichenoid interface dermatitis refers to a cutaneous inflammatory pattern in which keratinocyte cell death is the essential feature. These terms have evolved from the originally described lichenoid tissue reaction. These lesions are the basis for an important group of skin diseases in animals and people where cytotoxic T-cell-mediated epidermal damage is a major pathomechanism. Yet, for largely historical reasons these commonly used morphological diagnostic terms do not reflect the essential nature of the lesion. An emphasis on subsidiary lesions, such as the presence of a lichenoid band, and definitions based on anatomical features, such as location at the dermo-epidermal location, may cause confusion and even misdiagnosis. This review covers historical aspects of the terminology, including the origin of terms such as "lichenoid." The types of cell death involved and the histopathologic lesions are described. Etiopathogenesis is discussed in terms of aberrations of immune/inflammatory mechanisms focusing on cutaneous lupus erythematosus, erythema multiforme, and Stevens-Johnson syndrome/toxic epidermal necrolysis. Mechanisms have most extensively been studied in humans and laboratory animals and the discussion is centered on these species. As interface dermatitis is firmly entrenched in dermatological parlance, rather than using "cytotoxic" as its substitute, the terminologies "interface cytotoxic dermatitis" and "panepidermal cytotoxic dermatitis" are recommended, based on location and extent of epithelium affected.

Chronic rheumatologic disorders and cardiovascular disease risk in women

Cardiovascular disease (CVD) is a major health threat to women worldwide. In addition to traditional CVD risk factors, autoimmune conditions are increasingly being recognized as contributors to adverse CVD consequences in women. Chronic systemic autoimmune and inflammatory disorders can trigger premature and accelerated atherosclerosis, microvascular dysfunction, and thrombosis. The presence of comorbid conditions, duration of the autoimmune condition, disease severity, and treatment of underlying inflammation are all factors that impact CVD risk and progression. Early identification and screening of CVD risk factors in those with underlying autoimmune conditions may attenuate CVD in this population. Treatment with non-steroidal anti-inflammatory drugs, corticosteroids, disease modifying agents and biologics may influence CVD risk factors and overall risk. Multi-disciplinary and team-based care, clinical trials, and collaborative team-science studies focusing on systemic autoimmune conditions will be beneficial to advance care for women.

Autoantibodies in the pathogenesis of idiopathic inflammatory myopathies: Does the endoplasmic reticulum stress response have a role?

Idiopathic inflammatory myopathies (IIMs) are a group of rare, acquired autoimmune diseases characterized by profound muscle weakness and immune cell invasion into non-necrotic muscle. They are related to the presence of antibodies known as myositis-specific antibodies and myositis-associated antibodies, which are associated with various IIM phenotypes and the clinical prognosis. The possibility of the participation of other pathological mechanisms involved in the inflammatory response in IIM has been proposed. Such mechanisms include the overexpression of major histocompatibility complex class I in myofibers, which correlates with the activation of stress responses of the endoplasmic reticulum (ER). Taking into account the importance of the ER for the maintenance of homeostasis of the musculoskeletal system in the regulation of proteins, there is probably a relationship between immunological and non-immunological processes and autoimmunity, and an example of this might be IIM. We propose that ER stress and its relief mechanisms could be related to inflammatory mechanisms triggering a humoral response in IIM, suggesting that ER stress might be related to the triggering of IIMs and their auto-antibodies’ production.

Biologics in refractory idiopathic inflammatory myositis (IIM): What experience in juvenile vs adult myositis tells us about the use of biologics in pediatric IIM

Juvenile dermatomyositis (JDM) is an extremely heterogeneous orphan disease with limited amount of dedicated research on the subject matter. Recent research suggests that JDM may not just be the classic antibody driven complements mediated microangiopathy as was thought to be in the past. The etiopathogenesis of JDM also involves inappropriate stimulation of innate immune system followed by dysregulation of the adaptive immune response through dendritic cells. Many variable immune factors such as genetics, major histocompatibility complex expressions, immunohistochemical variabilities, and diversity in specific and associated autoantibodies may make individual IIM and JDM cases unique. The diversity in IIM and JDM also explains individual variability in response to specific therapies. Classifying and matching the right patients to the right treatment is crucial to the successful treatment of these patients with better outcomes. Sub-type specific biologic therapy may be the best current treatment that can match the patient to the best treatment options. A PubMed search was performed to find all the available cases of refractory myositis patients treated with biologics up to July 2020. Using this search this article reviews all the current biologic treatment options and experiences for both adults and children in the context of recent basic science to assist pediatric rheumatologists in choosing the optimal biologic therapy for a child with recalcitrant JDM.

JAK-inhibitors for dermatomyositis: A concise literature review

Refractory dermatomyositis (DM) is defined as cases that do not show improvement after initial treatment with two different immunosuppressives combined with corticosteroids with or without intravenous immunoglobulins. In recent years, few studies have reported a positive response to the use of Janus kinase inhibitors (JAK-inhibitors) for the treatment of refractory DM. A systematic literature review was performed for articles studying the use of JAK-inhibitors for the treatment of refractory DM. We identified 38 females and 15 males treated with JAK-inhibitors without serious side effects. Tofacitinib was the most frequently used JAK-inhibitor followed by ruxolitinib. Significant improvement in CDASI score, muscle strength, body weight, and skin lesions were reported in most of the studies. The duration of follow-up ranged from 1 to 15 months without relapse. Therefore, the use of JAK-inhibitors looks promising in the treatment of refractory DM and further high volume research may be required to validate the current concept. As only case reports and series were identified without direct comparison for review, there is a potential risk of bias. Despite these limitations, we believe that the result of this analysis allows a better understanding of treatment options for refractory DM and will help generate a hypothesis that can be further tested.

Dermatomyositis: immunological landscape, biomarkers, and potential candidate drugs

INTRODUCTION

Dermatomyositis (DM) is a rare inflammatory disease characterized by the invasion of the skin and muscles. Environmental, genetic, and immunological factors contribute to disease pathology. To date, no bioinformatics studies have been conducted on the potential pathogenic genes and immune cell infiltration in DM. Therefore, we aimed to identify differentially expressed genes (DEGs) and immune cells, as well as potential pathogenic genes and immune characteristics, which may be useful for the diagnosis and treatment of DM.

METHOD

GSE1551, GSE5370, GSE39454, and GSE48280 from Gene Expression Omnibus were included in our study. Limma, ClusterProfiler, and Kyoto Encyclopedia of Genes and Genomes were used to identify DEGs, Gene Ontology (GO), and perform pathway analyses, respectively. Cytoscape was used to construct the protein-protein interaction (PPI) network. Small-molecule drugs were identified using a connectivity map (CMap), and the TIMER database was used to identify infiltrating cells.

RESULTS

DEG analysis identified 12 downregulated and 163 upregulated genes. GO analysis showed that DEGs were enriched in immune-related pathways. Ten hub genes were identified from the PPI network. Additionally, CMap analysis showed that caffeic acid, sulfaphenazole, molindone, tiabendazole, and bacitracin were potential small-molecule drugs with therapeutic significance. We identified eight immune cells with differential infiltration in patients with DM and controls. Finally, we constructed a powerful diagnostic model based on memory B cells, M1, and M2 macrophages.

CONCLUSIONS

This study explored the potential molecular mechanism and immunological landscape of DM and may guide future research and treatment of DM.

KEY POINTS

• We explored the molecular mechanism and immunological landscape of dermatomyositis. • GO analysis showed that DEGs were enriched in immune-related pathways. • We predicted small-molecular drugs with potential therapeutic significance based on bioanalytical techniques. • We identified six immune cells with differential infiltration in patients with DM and controls.

The relationship between JAK2(V617F) mutation and dermatomyositis-a case report and literature review

The JAK family (JAK1, JAK2, JAK3, and TYK2) have recently emerged as a potential therapeutic management in controlling severe and refractory dermatomyositis. Meanwhile, the progress in the discovery of JAK blockers is significant, with an increasing number of selective JAK inhibitors reported and some are in or prepare for clinical trials. However, the importance of each JAK in dermatomyositis is unclear, which is critical for a comprehensive understanding of dermatomyositis and significant for forming mechanism-based strategy. Here, we presented a case with clinically amyopathic dermatomyositis and essential thrombocytosis with a somatic constitutive active mutation of JAK2(V617F). The coexistence of these two uncommon diseases attracted us to investigate their underlying relationship. To this end, we characterized the clinical course and laboratory findings of this patient. Particularly, we correlated JAK2(V617F) mutation burden in affected peripheral blood subset with clinical activity score of dermatomyositis. Based on our observation, we concluded that these two diseases are independent disorders, and JAK2(V617F) mutation burden is irrelevant to the severity of dermatomyositis. Finally, we reviewed the literature and summarized them with a thorough discussion.

The Value of Intravenous Immunoglobulin Therapy in Idiopathic Inflammatory Myositis in the Current Transformed Era of Biologics

The understanding of etiology and pathogenesis of idiopathic immune myositis is fast evolving, and so is the classification of myositis subtypes. The diversity in genetics, major histocompatibility complex expressions, immunohistochemical, and specific and associated autoantibodies not only explains the individual variability in response to therapies but also begs for subtype-specific treatments. With the evolution of the new biological therapies, the treatment of idiopathic immune myositis (IIM) has greatly transformed in recent years. This article appraises the current therapeutic value of intravenous immunoglobulin (IVIg) in idiopathic immune myopathy patients in the era of transformed treatment options. This article argues why the IVIg therapy still retains its value as an unreplaceable treatment option in certain specific subtypes of idiopathic immune myositis patients as well as in certain specific clinical idiopathic immune myositis scenarios.

Polymyositis and dermatomyositis - challenges in diagnosis and management

Polymyositis (PM) and dermatomyositis (DM) are different disease subtypes of idiopathic inflammatory myopathies (IIMs). The main clinical features of PM and DM include progressive symmetric, predominantly proximal muscle weakness. Laboratory findings include elevated creatine kinase (CK), autoantibodies in serum, and inflammatory infiltrates in muscle biopsy. Dermatomyositis can also involve a characteristic skin rash. Both polymyositis and dermatomyositis can present with extramuscular involvement. The causative factor is agnogenic activation of immune system, leading to immunologic attacks on muscle fibers and endomysial capillaries. The treatment of choice is immunosuppression. PM and DM can be distinguished from other IIMs and myopathies by thorough history, physical examinations and laboratory evaluation and adherence to specific and up-to-date diagnosis criteria and classification standards. Treatment is based on correct diagnosis of these conditions.

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Challenges of diagnosis and management influences the clinical research and practice of Polymyositis and dermatomyositis.

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Diagnostic criteria have been updated and novel therapies have been developed in PM/DM.

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Pathogenesis investigation and diagnosis precision improvement may help to guide future treatment strategies.

Blood purification in two patients with clinically amyopathic dermatomyositis associated with interstitial lung disease with anti-melanoma differentiation-associated gene-5 antibody (MDA-5)

Patients of clinically amyopathic dermatomyositis associated with rapidly progressive interstitial pneumonia (CADM-RFIP) with positive anti-MDA5 antibody usually presents rapid deterioration and traditional therapy such as cyclophosphamide combined with high-dose prednisone pulse therapy shows no clear benefit at whiles. However, blood purification combined with traditional therapy works according to the literature. We herein report two CADM-RFIP patients administered with DNA immunoadsorption combined with traditional therapy and then reviewed the literature of blood purification in CADM-RFIP patients at home and abroad to date. We emphasize blood purification such as DNA immunoadsorption could apply in the early stage of CADM-RFIP, which can decrease inflammation and allow us more time to control the condition better.

The Immune Response and the Pathogenesis of Idiopathic Inflammatory Myositis: a Critical Review

The pathogenesis of idiopathic inflammatory myositis (IIMs, including polymyositis and dermatomyositis) remains largely enigmatic, despite advances in the study of the role played by innate immunity, adaptive immunity, genetic predisposition, and environmental factors in an orchestrated response. Several factors are involved in the inflammatory state that characterizes the different forms of IIMs which share features and mechanisms but are clearly different with respect to the involved sites and characteristics of the inflammation. Cellular and non-cellular mechanisms of both the immune and non-immune systems have been identified as key regulators of inflammation in polymyositis/dermatomyositis, particularly at different stages of disease, leading to the fibrotic state that characterizes the end stage. Among these, a special role is played by an interferon signature and complement cascade with different mechanisms in polymyositis and dermatomyositis; these differences can be identified also histologically in muscle biopsies. Numerous cellular components of the adaptive and innate immune response are present in the site of tissue inflammation, and the complexity of idiopathic inflammatory myositis is further supported by the involvement of non-immune mechanisms such as hypoxia and autophagy. The aim of this comprehensive review is to describe the major pathogenic mechanisms involved in the onset of idiopathic inflammatory myositis and to report on the major working hypothesis with therapeutic implications.

Dysregulated innate immune function in the aetiopathogenesis of idiopathic inflammatory myopathies

The idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of systemic muscle conditions that are believed to be autoimmune in nature. They have distinct pathological features, but the aetiopathogenesis of each subtype remains largely unknown. Recently, there has been increased interest in the complex role the innate immune system plays in initiating and perpetuating these conditions, and how this may differ between subtypes. This article summarises the traditional paradigms of IIM pathogenesis and reviews the accumulating evidence for disturbances in innate immune processes in these rare, but debilitating chronic conditions.

Bioinformatics analysis of gene expression profiles of dermatomyositis

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

Update on the role of plasmacytoid dendritic cells in inflammatory/autoimmune skin diseases

Plasmacytoid dendritic cells (pDCs) represent a specialized dendritic cell population that exhibit plasma cell morphology, express CD4, CD123, blood-derived dendritic cell antigen-2 (BDCA-2) and Toll-like receptor (TLR)7 and TLR9 within endosomal compartments. When activated, pDCs are capable of producing large quantities of type I IFNs (mainly IFN-α/β), which provide antiviral resistance and link the innate and adaptive immunity. While generally lacking from normal skin, pDCs infiltrate the skin and appear to be involved in the pathogenesis of several inflammatory, infectious (especially viral) and neoplastic entities. In recent years, pDC role in inflammatory/autoimmune skin conditions has been extensively studied. Unlike type I IFN-mediated protective immunity that pDCs provide at the level of the skin by regulated sensing of microbial or self-nucleic acids upon skin damage, excessive sensing may elicit IFN-driven inflammatory/autoimmune diseases. In this review, focus will be on the role of pDCs in cutaneous inflammatory/autoimmune dermatoses.

Chloroquine analogues in drug discovery: new directions of uses, mechanisms of actions and toxic manifestations from malaria to multifarious diseases

Antimalarial drugs (e.g. chloroquine and its close structural analogues) were developed primarily to treat malaria; however, they are beneficial for many dermatological, immunological, rheumatological and severe infectious diseases, for which they are used mostly today. Chloroquine and hydroxychloroquine, two of the most fascinating drugs developed in the last 50 years, are increasingly recognized for their effectiveness in myriad non-malarial diseases. In advanced research, chloroquine and hydroxychloroquine have been shown to have various immunomodulatory and immunosuppressive effects, and currently have established roles in the management of rheumatic diseases, lupus erythematosus (different forms) and skin diseases, and in the treatment of different forms of cancer. Recently, chloroquine analogues have also been found to have metabolic, cardiovascular, antithrombotic and antineoplastic effects. This review is concerned with the lysosomotropic, anti-inflammatory and immunomodulatory mechanisms of chloroquine, hydroxychloroquine, quinacrine and related analogues, and the current evidence for both their beneficial effects and potential adverse manifestations in various diseases.