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

Pathologic Changes in and Immunophenotyping of Polymyositis in the Dutch Kooiker Dog

Earlier, we described a breed-specific inflammatory myopathy in Dutch Kooiker dogs (Het Nederlandse Kooikerhondje), one of the nine Dutch breeds. The disease commonly manifests itself with clinical signs of difficulty walking, muscle weakness, exercise intolerance, and/or dysphagia. In nearly all dogs' creatine kinase (CK) activity was elevated. Histopathology reveals the infiltration of inflammatory cells within the skeletal muscles. The objective of this study was to further investigate and characterize the histopathological changes in muscle tissue and immunophenotype the inflammatory infiltrates. FFPE fixed-muscle biopsies from 39 purebred Kooiker dogs were included and evaluated histopathologically according to a tailored classification scheme for skeletal muscle inflammation. As in other breed-related inflammatory myopathies, multifocal, mixed, and predominantly mononuclear cell infiltration was present, with an initial invasion of viable muscle fibres and the surrounding stroma leading to inflammation, necrosis, and tissue damage. Immunophenotyping primarily revealed lymphohistiocytic infiltrates, with CD3+ T-cells being the predominant inflammatory cell type, accompanied by CD8+ cytotoxic T-cells. The concurrent expression of MHC-II class molecules on myofibres suggests their involvement in initiating and maintaining inflammation. Additionally, CD20+ B-cells were identified, though in lower numbers compared to T-cells, and IBA-1-positive macrophages were frequently seen. These findings suggest a breed-specific subtype of polymyositis in Kooiker dogs, akin to other breeds. This study sheds light on the immune response activation, combining adaptive and innate mechanisms, contributing to our understanding of polymyositis in this breed.

ASM is a therapeutic target in dermatomyositis by regulating the differentiation of naive CD4 + T cells into Th17 and Treg subsets

BACKGROUND

This study aims to investigate the involvement of acid sphingomyelinase (ASM) in the pathology of dermatomyositis (DM), making it a potential therapeutic target for DM.

METHODS

Patients with DM and healthy controls (HCs) were included to assess the serum level and activity of ASM, and to explore the associations between ASM and clinical indicators. Subsequently, a myositis mouse model was established using ASM gene knockout and wild-type mice to study the significant role of ASM in the pathology and to assess the treatment effect of amitriptyline, an ASM inhibitor. Additionally, we investigated the potential treatment mechanism by targeting ASM both in vivo and in vitro.

RESULTS

A total of 58 DM patients along with 30 HCs were included. The ASM levels were found to be significantly higher in DM patients compared to HCs, with median (quartile) values of 2.63 (1.80-4.94) ng/mL and 1.64 (1.47-1.96) ng/mL respectively. The activity of ASM in the serum of DM patients was significantly higher than that in HCs. Furthermore, the serum levels of ASM showed correlations with disease activity and muscle enzyme levels. Knockout of ASM or treatment with amitriptyline improved the severity of the disease, rebalanced the CD4 T cell subsets Th17 and Treg, and reduced the production of their secreted cytokines. Subsequent investigations revealed that targeting ASM could regulate the expression of relevant transcription factors and key regulatory proteins.

CONCLUSION

ASM is involved in the pathology of DM by regulating the differentiation of naive CD4 + T cells and can be a potential treatment target.

IFNγ causes mitochondrial dysfunction and oxidative stress in myositis

Idiopathic inflammatory myopathies (IIMs) are severe autoimmune diseases with poorly understood pathogenesis and unmet medical needs. Here, we examine the role of interferon γ (IFNγ) using NOD female mice deficient in the inducible T cell co-stimulator (Icos), which have previously been shown to develop spontaneous IFNγ-driven myositis mimicking human disease. Using muscle proteomic and spatial transcriptomic analyses we reveal profound myofiber metabolic dysregulation in these mice. In addition, we report muscle mitochondrial abnormalities and oxidative stress in diseased mice. Supporting a pathogenic role for oxidative stress, treatment with a reactive oxygen species (ROS) buffer compound alleviated myositis, preserved muscle mitochondrial ultrastructure and respiration, and reduced inflammation. Mitochondrial anomalies and oxidative stress were diminished following anti-IFNγ treatment. Further transcriptomic analysis in IIMs patients and human myoblast in vitro studies supported the link between IFNγ and mitochondrial dysfunction observed in mice. These results suggest that mitochondrial dysfunction, ROS and inflammation are interconnected in a self-maintenance loop, opening perspectives for mitochondria therapy and/or ROS targeting drugs in myositis.

Peripheral Blood Lymphocyte Subsets and Heterogeneity of B Cell Subsets in Patients of Idiopathic Inflammatory Myositis with Different Myositis-specific Autoantibodies

Idiopathic inflammatory myopathies (IIM) are a group of myopathies that present with muscle weakness and multiple extra-muscular manifestations, in which lymphocytes play central roles in myositis pathogenesis. This study aimed to explore the clinical characteristics of lymphocyte subsets, especially B cell subsets, in patients with IIM. Our study included 176 patients with active IIM and 210 gender/age-matched healthy controls (HCs). Compared to HCs, patients have reduced counts of T cells, B cells, and natural killer cells. In addition, B cell subsets from 153 patients with IIM and 92 HCs were characterized. Patients had a lower percentage of memory B cells and translational memory B cells, while those patients were with an elevated percentage of CD19+ B cells, plasmablast and naïve B cells compared with HCs. Moreover, to further explore the heterogeneity of B cells in IIM, patients were categorized into three clusters based on clustering analysis. Cluster 1 was dominated by CD19+ B cells, Bregs and naïve B cells, cluster 3 was dominated by memory B cells and plasmablast, and cluster 2 had the highest proportion of translational memory B cells. Notably, patients in cluster 1 presented with higher CK levels, indicating muscle damage, whereas patients in cluster 3 showed a higher incidence of chest tightness. Our study indicated that lymphopenia is a common manifestation in patients with IIM. B cell subsets are abnormally expressed and showed high heterogeneity in patients with IIM. The patients with IIM were divided into three different clusters with different percentages of chest tightness and distinct CK levels.

Increased expression of the p-STAT3/IL-17 signaling pathway in patients with dermatomyositis

OBJECTIVES

The aim is to explore the roles of phosphorylated signal transduction and activator of transcription 3 (p-STAT3) and interleukin (IL)-17 in patients with dermatomyositis (DM).

METHODS

A total of 20 DM patients and 12 healthy controls were enrolled. Flow cytometry combined with counting was used to detect the number of Th17 cells. Western blotting and immunohistochemistry were used to examine the muscle levels of p-STAT3 and IL-17, and serum levels of IL-17 were measured by enzyme-linked immunosorbent assays.

RESULTS

Muscle p-STAT3 and IL-17 levels, the number of Th17 cells, and serum IL-17 levels were markedly increased in DM. p-STAT3 and IL-17 were co-expressed in the muscle of DM patients. The p-STAT3 levels were correlated with the number of Th17 cells as well as muscle and serum IL-17 levels. The correlations of the p-STAT3 level with elevated levels of transaminases, myocardial enzymes, and the health assessment questionnaire score were significantly positive, while the correlation with manual muscle testing-8 was significantly negative. A receiver operating characteristic curve indicated the good predictive value of p-STAT3 for the occurrence of DM.

CONCLUSIONS

The increased p-STAT3/IL-17 signaling pathway activation in DM patients may induce muscle inflammation and necrosis, and it may be a potential target for DM.

Characteristics and prognostic implications of peripheral blood lymphocyte subsets in patients with anti-MDA5 antibody positive dermatomyositis-interstitial lung disease

OBJECTIVES

To examine the characteristics of blood lymphocyte subsets in dermatomyositis-interstitial lung disease (DM-ILD) inflicted patients with positive anti-melanoma differentiation-associated gene 5 (anti-MDA5), as well as its prognosis value in this set of patients.

METHODS

Data were retrospectively collected from 253 DM-ILD patients from three hospitals in China between January 2016 to January 2021. Patients were grouped into anti-MDA5 antibody positive group (MDA5+ DM-ILD) and anti-MDA5 antibody negative group (MDA5- DM-ILD) based on myositis-specific autoantibody test results. Demographic characteristics, lymphocyte subsets patterns and other clinical features were compared between the two groups. The association of lymphocyte subsets with 180-day mortality was investigated using survival analysis in MDA5+ DM-ILD.

RESULTS

Out of 253 eligible patients with DM-ILD, 59 patients were anti-MDA5+ and 194 were anti-MDA5-. Peripheral blood lymphocyte count, CD3+ count, percentage of CD3+, CD3+CD4+ count, and CD3+CD8+ count was lower in MDA5+ DM-ILD than in MDA5- DM-ILD- (all P < 0.001) as well as CD3-CD19+ count (P = 0.04). In MDA5+ DM-ILD, CD3+CD8+ count ≤ 49.22 cell/μL (HR = 3.81, 95%CI [1.20,12.14]) and CD3-CD19+ count ≤ 137.64 cell/μL (HR = 3.43, 95%CI [1.15,10.24]) were independent predictors of mortality. CD3+CD8+ count ≤ 31.38 cell/μL was associated with a higher mortality risk in all DM-ILD patients (HR = 8.6, 95%CI [2.12,31.44]) after adjusting for anti-MDA5 and other clinical characteristics.

CONCLUSION

Significant lymphocytes decrease was observed in MDA5+ DM-ILD patients. CD3+CD8+ cell count was associated with worse prognosis in both MDA5+ DM-ILD and all DM-ILD patients.

Metagenome-wide association study of gut microbiome features for myositis

PURPOSE

The clinical relevance and pathogenic role of gut microbiome in both myositis and its associated interstitial lung disease (ILD) are still unclear. The purpose of this study was to investigate the role of gut microbiome in myositis through comprehensive metagenomic-wide association studies (MWAS).

METHODS

We conducted MWAS of the myositis gut microbiome in a Chinese cohort by using whole-genome shotgun sequencing of high depth, including 30 myositis patients and 31 healthy controls (HC). Among the myositis patients, 11 developed rapidly progressive interstitial lung disease (RP-ILD) and 10 had chronic ILD (C-ILD).

RESULTS

Analysis for overall distribution level of the bacteria showed Alistipes onderdonkii, Parabacteroides distasonis and Escherichia coli were upregulated, Lachnospiraceae bacterium GAM79, Roseburia intestinalis, and Akkermansia muciniphila were downregulated in patients with myositis compared to HC. Bacteroides thetaiotaomicron, Parabacteroides distasonis and Escherichia coli were upregulated, Bacteroides A1C1 and Bacteroides xylanisolvens were downregulated in RP-ILD cases compared with C-ILD cases. A variety of biological pathways related to metabolism were enriched in the myositis and HC, RP-ILD and C-ILD comparison. And in the analyses for microbial contribution in metagenomic biological pathways, we have found that E. coli played an important role in the pathway expression in both myositis group and myositis-associated RP-ILD group. Anti-PL-12 antibody, anti-Ro-52 antibody, and anti-EJ antibody were found to have positive correlation with bacterial diversity (Shannon-wiener diversity index and Chao1, richness estimator) between myositis group and control groups. The combination of E. coli and R. intestinalis could distinguish myositis group from HC effectively. R. intestinalis can also be applied in the distinguishment of RP-ILD group vs. C-ILD group in myositis patients.

CONCLUSION

Our MWAS study first revealed the link between gut microbiome and pathgenesis of myositis, which may help us understand the role of gut microbiome in the etiology of myositis and myositis-associated RP-ILD.

Association between air pollution exposure and outpatient visits for dermatomyositis in a humid subtropical region of China: a time-series study

In recent years, a growing number of studies have found that air pollution plays critical roles in the onset and development of autoimmune diseases, but few studies have shown an association between air pollutants and dermatomyositis (DM). We sought to investigate the relationship between short-term exposure to air pollution and outpatient visits for DM and to quantify the burden of DM due to exposure to air pollutants in Hefei, China. Daily records of hospital outpatient visits for DM, air pollutants and meteorological factors data in Hefei from January 1, 2018 to December 31, 2021 were obtained. We used a distributed lag non-linear model (DLNM) in conjunction with a generalized linear model (GLM) to explore the association between air pollution and outpatient visits for DM, and conducted stratified analyses by gender, age and season. Moreover, we used attributable fraction (AF) and attributable number (AN) to reflect the burden of disease. A total of 4028 DM clinic visits were recorded during this period. High concentration nitrogen dioxide (NO2) exposure was associated with increased risk of DM outpatient visits (relative risk (RR) 1.063, 95% confidence interval (CI) 1.015-1.114, lag 0-5). Intriguingly, exposure to high concentration ozone (O3) was associated with reduced risk of outpatient visits for DM (RR 0.974, 95% CI 0. 0.954-0.993, lag 0-6). The results of stratified analyses showed that the cold season (vs. warm season) were more susceptible to outpatient visits for DM associated with NO2 and O3 exposure. In addition, we observed that an increased risk of DM outpatient visits was attributable to high concentration NO2 exposure, while high concentration O3 exposure was associated with a decreased risk of DM outpatient visits. This study provided a scientific basis for the etiology research and health protection of DM.

Targeting intracellular pathways in idiopathic inflammatory myopathies: A narrative review

In recent decades, several pieces of evidence have drawn greater attention to the topic of innate immunity, in particular, interferon (IFN) and Interleukin 6 in the pathogenesis of idiopathic inflammatory myopathies (IIM). Both of these molecules transduce their signal through a receptor coupled with Janus kinases (JAK)/signal transducer and activator of transcription proteins (STAT). In this review, we discuss the role of the JAK/STAT pathway in IIM, evaluate a possible therapeutic role for JAK inhibitors in this group of diseases, focusing on those with the strongest IFN signature (dermatomyositis and antisynthetase syndrome).

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.

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.

Characterisation of Disease Patterns of Dermatomyositis with Different Initial Manifestations

Purpose

To determine the characteristics and prognoses of dermatomyositis (DM) by comparing the difference in initial symptoms.

Patients and Methods

A retrospective analysis was performed on the patients diagnosed with DM from 1 January 2019 to 1 January 2021. Based on the firstly presented symptoms, patients were divided into five groups, namely rash group, muscle weakness group, arthritis group, respiratory symptom group and atypical symptom group. Clinical and laboratory data were recorded. All patients were followed up until 31 May 2021.

Results

In total 136 DM patients, rash (40%) was the most common initial symptom, followed by respiratory symptoms (22%), arthritis (20%), muscle weakness (10%) and atypical symptoms (8%). Rash group and atypical group had a higher positive rate of anti-TIF1γ antibodies than arthritis group and respiratory symptom group (P < 0.05). Respiratory symptom and arthritis groups had a higher positive rate of anti-Ro52 antibodies than rash and muscle weakness groups (P < 0.05). Respiratory group had a higher incidence of ILD than rash and atypical groups. The FVC and DLCO in respiratory group were significantly lower than rash group, arthritis group and atypical group (P < 0.05). The survival rate of rash group was significantly higher than muscle weakness group and arthritis group (P < 0.05).

Conclusion

DM patients with different initial manifestations had different myositis antibodies and prognoses.

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.

Involvement of Type-I Interferon Signaling in Muscle Stem Cell Proliferation During Dermatomyositis

Background and objective:

The idiopathic inflammatory myopathy Dermatomyositis (DM) is an acquired disease that combines muscle, lung and skin impairments. DM patients show a wide range of severity of proximal skeletal muscle weakness, associated with inflammatory infiltrates, vasculitis, and capillary dropout, perifascicular myofiber atrophy. Moreover, DM muscles show signs of muscle regeneration. Since muscle stem cells (MuSCs) are responsible for myofiber repair, we asked wether the proliferative properties of muscle stem cells (MuSCs) are altered in DM muscle. We investigated the role of type-I interferon (IFN-I) in this process since DM is associated with sustained inflammation with high IFN-I levels.

Methods:

MuSCs isolated from normal, adult and juvenile DM muscles were grown in culture and were analyzed in vitro for their proliferating properties, their myogenic capacities and their senescence. Gain and loss of function experiments were performed to assess the role of IFN-I signaling in the prolfierative capacities of MuSCs.

Results:

MuSCs derived from 8 DM adult patients (DM-MuSCs) (5 severe form and 3 mild form, established from histological evaluation), from 3 juvenile DM patients and from normal muscle were used to analyze their myogenesis in vitro. DM-MuSCs exhibited strongly reduced proliferating capacities as compared with healthy MuSCs (-31 to -43% for severe and mild DM, respectively), leading to poor myotube formation (-36 to -71%). DM-MuSCs were enriched in senescent, beta-galactosidase positive cells, explaining partly the proliferation defect. Gain and loss of function experiments were performed to assess the role of IFN-I on the proliferative capacity of MuSCs. High concentrations of IFN-I decreased the proliferation of healthy MuSCs. Similarly, conditioned-medium from DM-MuSCs decreased the proliferation of healthy MuSC (-15 to -22%), suggesting the delivery of an autocrine effector. Then, pharmacological blockade of the IFN signaling (using ruxolitinib or anti-IFN-receptor antibodies) in DM-MuSCs rescued their proliferation up to the control values.

Discussion:

These results show that autocrine IFN-I signaling prevents MuSC expansion, leading to muscle repair deficit. This process may explain the persistent muscle weakness observed in severe DM patients.

Muscle Biopsy: A Requirement for Precision Medicine in Adult-Onset Myopathy

Muscle biopsy is a fundamental procedure to assist the final diagnosis of myopathy. With the recent advances in molecular diagnosis, serology tests, and mechanism-based classification in myopathy, the précised diagnosis for myopathy required the applications of multiple tools. This study intends to reappraise the benefit of muscle biopsy in adult-onset myopathy under the setting of an optimized muscle biopsy protocol and comprehensive serology tests. A one-group pretest-posttest study design was used. The pre- and post-biopsy diagnoses and treatments in 69 adult patients were compared. Muscle biopsy yielded 85.5% of definitive diagnoses, including changes in pre-biopsy diagnoses (40.6%) and narrowing down the suspicious myopathies (49.3%). The demographic data and clinical parameters between the group “with change” and “without change” after biopsy were not different. Among those with changes in diagnosis, 39.3% also had a corresponding shift in treatment, which benefits the patients significantly. Regarding the most common adult-onset myopathy, idiopathic inflammatory myopathy (IIM), 41% of patients with pre-biopsy diagnosis as IIM had changes in their IIM subtype diagnosis, and 53% was finally not IIM after muscle biopsy. Although there have been advances in molecular diagnosis recently, muscle biopsy still undoubtedly critically guided the diagnosis and treatment of adult-onset myopathy in the era of precision medicine.

Enhanced toxicity to chemoradiation in a patient with Anti-Jo-1-antisynthetase syndrome

Appropriate counseling of patients with autoimmune connective tissue disorders (ACTDs) is often challenging for radiation oncologists, especially regarding anticipated side-effects of radiation treatment. These patients can have highly variable and unpredictable sequelae from radiation therapy, and the uncertainty builds when radiation is convoluted by the addition of concurrent chemotherapy. While many patients may experience a mild intensification of toxicity above what is expected, some patients experience much more severe toxicity. These patients become critical learning cases, enabling a better understanding of the delicate and complex ways in which radiation response is altered in the context of ACTDs while allowing other patients with similar ACTD profiles to benefit from past experience. Our report makes an important contribution to this space by describing a particularly severe case of toxicity that manifested in such a patient and the ensuing clinical decision-making. Comprehensive genotyping of classic pharmacokinetic and pharmacodynamic pathway genes (including mutations in DPD and CDA) did not reveal any signatures that might explain her enhanced toxicity and we demonstrate that severe toxicity can still manifest in the era of modern conformal radiation treatments for rectal cancer. We urge caution in the treatment of patients with rare ACTDs, but also emphasize that curative treatment should not be withheld in such patients. We conclude by advocating for the development and maintenance of a prospective multiinstitutional database of patients with ACTDs to help inform and improve future practice.

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.

Plasma exosomal RNAs has potential as both clinical biomarkers and therapeutic targets of dermatomyositis

OBJECTIVES

Dermatomyositis (DM) is characterized by skeletal muscle weakness and cutaneous manifestations. Plasma exosomes (EXOs) contain proteins, RNAs, DNA, and lipid cargoes and are transferred among cells. Deeply investigated plasma EXO RNAs potentially improve our understanding of DM pathogenesis. We aimed to identify new potential biomarkers and therapeutic targets of DM.

METHODS

The RNAs (mRNA, miRNA and lncRNA) profiles of plasma EXOs were evaluated by sequencing on the Illumina HiSeq 3000 platform. Differentially expressed (DE) RNAs and bioinformatic analyses were performed. Human skeletal muscle myoblasts (HSkMCs) were stimulated with plasma EXOs, rapamycin or IFN-β. Real-time PCR and western blot were used to detect related genes and proteins.

RESULTS

A total of 689 DE mRNAs, 53 DE miRNAs and 452 DE lncRNAs were identified in DM plasma EXOs. Bioinformatic analysis inferred that plasma EXOs were secreted mainly by CD8+ T cells, regulatory T cells and natural killer cells. The DE miRNAs participated in the autophagy, TGF-β and Wnt signalling pathways. Three DE miRNAs (hsa-miR-125a-3p, hsa-miR-1246 and hsa-miR-3614-5p) were correlated with serological indices, organs involvement and myositis-specific autoantibodies. The DE lncRNAs participated in autophagy, interferon-β production and mTOR signalling. DM plasma EXOs can induce autophagy in HSkMCs by regulating 3 miRNAs (hsa-miR-125a-3p, hsa-miR-1246 and hsa-miR-3614-5p) and 3 lncRNAs (ENST00000584157.1, ENST00000523380.1, and ENST00000560054.1), which formed an autophagy network, playing the muscle damage roles.

CONCLUSIONS

Our study provides an overview of distinct RNAs profiles in DM plasma EXOs, and verified some miRNAs as potential biomarkers and therapeutic targets. The findings provide important clues for more in-depth explorations of plasma EXOs in DM.

Lymphocyte immunophenotyping in inflammatory myositis: a review

PURPOSE OF REVIEW

This is a comprehensive review of the current knowledge on predominant immune cell phenotypes involved in idiopathic inflammatory myopathies (IIM).

RECENT FINDINGS

Major circulating immune cell subpopulations described in IIM encompass the lymphocyte compartment. An unbalance in T cell subsets seems to consistently affect the peripheral and muscle compartment, with a predominance of CD4+ T and B cells in dermatomyositis, CD8+ T cells in polymyositis/inclusion body myositis (IBM) and novel findings highlighting novel proinflammatory T subsets, that is, CD8+Tbet+ and CD28- T cells across different IIM subsets. On the other hand, an impairment in Treg cells number and function has been described especially across polymyositis/dermatomyositis and IBM. Total T follicular helper (Tfh) cells, increased in immune-mediated necrotizing myopathy, skewed toward Tfh2 and Tfh17 in dermatomyositis, polymyositis, and juvenile dermatomyositis. B cell compartment is more rarely described in IIM, yet an unbalance in this pool is as well likely. Evidence of plasma cells increased in polymyositis, dermatomyositis, IBM, and Bregs decreased in dermatomyositis have been reported. Perturbations in the memory and naïve subsets are common in dermatomyositis/polymyositis and antisynthetase syndrome.

SUMMARY

Protean immune cell abnormalities characterize different IIM subsets, reflecting the complexity of these autoimmune conditions. A deeper understanding of B-cell and T-cell immunophenotyping may promote early diagnosis and identification of new potential therapeutic targets.

A Hypoxia Gene-Based Signature to Predict the Survival and Affect the Tumor Immune Microenvironment of Osteosarcoma in Children

Osteosarcoma is a quickly developing, malignant cancer of the bone, which is associated with a bad prognosis. In osteosarcoma, hypoxia promotes the malignant phenotype, which results in a cascade of immunosuppressive processes, poor prognosis, and a high risk of metastasis. Nonetheless, additional methodologies for the study of hyperoxia in the tumor microenvironment also need more analysis. We obtained 88 children patients with osteosarcoma from the Therapeutically Applicable Research to Generate Effective Treatment (TARGET) database and 53 children patients with RNA sequence and clinicopathological data from the Gene Expression Omnibus (GEO). We developed a four-gene signature related to hypoxia to reflect the immune microenvironment in osteosarcoma that predicts survival. A high-risk score indicated a poor prognosis and immunosuppressive microenvironment. The presence of the four-gene signature related to hypoxia was correlated with clinical and molecular features and was an important prognostic predictor for pediatric osteosarcoma patients. In summary, we established and validated a four-gene signature related to hypoxia to forecast recovery and presented an independent prognostic predictor representing overall immune response strength within the osteosarcoma microenvironment.

Pervasive inflammatory activation in patients with deficiency in very-long-chain acyl-coA dehydrogenase (VLCADD)

OBJECTIVES

Very-long-chain acyl-CoA dehydrogenase deficiency (VLCADD) is a disorder of fatty acid oxidation. Symptoms are managed by dietary supplementation with medium-chain fatty acids that bypass the metabolic block. However, patients remain vulnerable to hospitalisations because of rhabdomyolysis, suggesting pathologic processes other than energy deficit. Since rhabdomyolysis is a self-destructive process that can signal inflammatory/immune cascades, we tested the hypothesis that inflammation is a physiologic dimension of VLCADD.

METHODS

All subjects (n = 18) underwent informed consent/assent. Plasma cytokine and cytometry analyses were performed. A prospective case analysis was carried out on a patient with recurrent hospitalisation. Health data were extracted from patient medical records.

RESULTS

Patients showed systemic upregulation of nine inflammatory mediators during symptomatic and asymptomatic periods. There was also overall abundance of immune cells with high intracellular expression of IFNγ, IL-6, MIP-1β (CCL4) and TNFα, and the transcription factors p65-NFκB and STAT1 linked to inflammatory pathways. A case analysis of a patient exhibited already elevated plasma cytokine levels during diagnosis in early infancy, evolving into sustained high systemic levels during recurrent rhabdomyolysis-related hospitalisations. There were corresponding activated leukocytes, with higher intracellular stores of inflammatory molecules in monocytes compared to T cells. Exposure of monocytes to long-chain free fatty acids recapitulated the cytokine signature of patients.

CONCLUSION

Pervasive plasma cytokine upregulation and pre-activated immune cells indicate chronic inflammatory state in VLCADD. Thus, there is rationale for practical implementation of clinical assessment of inflammation and/or translational testing, or adoption, of anti-inflammatory intervention(s) for personalised disease management.

Autoantibodies targeting TRIM72 compromise membrane repair and contribute to inflammatory myopathy

Idiopathic inflammatory myopathies (IIM) involve chronic inflammation of skeletal muscle and subsequent muscle degeneration due to an uncontrolled autoimmune response; however, the mechanisms leading to pathogenesis are not well understood. A compromised sarcolemmal repair process could promote an aberrant exposure of intramuscular antigens with the subsequent initiation of an inflammatory response that contributes to IIM. Using an adoptive transfer mouse model of IIM, we show that sarcolemmal repair is significantly compromised in distal skeletal muscle in the absence of inflammation. We identified autoantibodies against TRIM72 (also known as MG53), a muscle-enriched membrane repair protein, in IIM patient sera and in our mouse model of IIM by ELISA. We found that patient sera with elevated levels of TRIM72 autoantibodies suppress sarcolemmal resealing in healthy skeletal muscle, and depletion of TRIM72 antibodies from these same serum samples rescues sarcolemmal repair capacity. Autoantibodies targeting TRIM72 lead to skeletal muscle fibers with compromised membrane barrier function, providing a continuous source of autoantigens to promote autoimmunity and further amplifying humoral responses. These findings reveal a potential pathogenic mechanism that acts as a feedback loop contributing to the progression of IIM.

Predictive Features and Clinical Presentation of Interstitial Lung Disease in Inflammatory Myositis

Interstitial lung disease (ILD) represents one of the most severe extra-muscular features of idiopathic inflammatory myositis (IIM). We aimed to identify any clinical and serological predictors of ILD in a monocentric cohort of 165 IIM patients.

ILD+ patients were defined as having restrictive impairment in lung function tests and signs of ILD at chest high-resolution computed tomography (HRCT). Available HRCT images were centralized and classified in different ILD patterns: non-specific interstitial pneumonia (NSIP), organizing pneumonia (OP), usual interstitial pneumonia-like (UIP), indeterminate for UIP, and interstitial lung abnormalities (ILA). Lung function test data were recorded at onset, at 1 and 5 years after ILD diagnosis.

ILD was found in 52 IIM patients (31.5%): 46.2% was affected by anti-synthetase syndrome (ARS), 21% by polymyositis (PM), 19% by dermatomyositis (DM), and 13.5% by overlap myositis. Most of ILD+ showed NSIP (31.9%), OP (19%), indeterminate for UIP (19%), and UIP (12.8%) patterns. At multivariate analysis, ILD was predicted by anti-Ro52 (p: 0.0026) and dyspnea (p: 0.015) at IIM onset. Most of ILD onset within is 12 months after IIM. In five cases, ILD occurs after 12 months since IIM diagnosis: these patients more frequently show dry cough and anti-Ku antibodies. Anti-Ro52 + ILD patients showed a significant increase of DLCO at 1 and 5 years of follow-up, compared with anti-Ro52 negative cases.

ILD occurs in about one third of IIM and was predicted by dyspnea at onset and anti-Ro52 antibodies. Anti-Ro52 defines a subgroup of ILD showing a significant improvement of DLCO during follow-up.

This retrospective study has been approved by local ethic committee (ASST-Spedali Civili of Brescia, Italy); protocol number: NP3511

Serum protein biomarkers for juvenile dermatomyositis: a pilot study

BACKGROUND

Blood accessible biomarkers to assess disease activity and their response to therapies in Juvenile Dermatomyositis (JDM) are urgently needed. This pilot study aims to identify serum protein biomarkers associated with clinical disease activity in untreated JDM and their response to medical therapy.

METHODS

SomaScan® technology screened JDM patients for 1305 proteins at three points: 1) before start of treatment, 2) while on therapy, and 3) after treatment tapering when patients were clinically inactive. To define disease associated biomarkers, SomaScan® data from untreated JDM patients (n = 8) were compared to SomaScan® data from an independent age-matched healthy control group (n = 12). Longitudinal analysis defined treatment responsive proteins at three time points: untreated (7 samples), treated (7 samples), and clinically inactive (6 samples). To confirm the SomaScan® data, a subset of nine candidate proteins (CXCL11, IL-17B, IL-17D, IL-22, CXCL10, MCP-1, ANGPT2, MIF, IL-23) were tested by ELISA after adding 2 JDM (one untreated, one clinically inactive) serum samples to the same group of JDM girls (8 untreated, 7 treated; 7 clinically inactive) as well as with 17 age, gender, matched healthy controls.

RESULTS

Comparison of untreated JDM versus healthy controls identified 202 elevated and 49 decreased serum proteins in JDM patients with an adjusted p-value < 0.001. Only 82 out of 251 identified biomarker candidates responded to treatment while 12 out of these 82 proteins returned to their original untreated disease levels upon therapy tapering. The ELISA testing of the untreated samples for nine candidate proteins confirmed previously known biomarkers (CXCL10 or IP-10, CXCL11 or I-TAC and MCP-1) and identified novel biomarkers including IL-22, Angiopoetin-2, and IL-17B in a cross-sectional analysis comparing 8 untreated JDM and 17 age/gender matched controls. The subsequent longitudinal data by ELISA were not concordant for some biomarkers (IL-22 and IL-17B), but the other biomarkers either normalized or rebounded concordantly.

CONCLUSIONS

Blood accessible protein biomarkers reflecting JDM pathophysiology were identified; some of them rebounded after therapy was tapered. Further studies bridging these biomarkers to specific clinical features of JDM are required to confirm the clinical utility of these serum protein biomarkers.

Clinical trials and novel therapeutics in dermatomyositis

INTRODUCTION

Currently, there are no proven drugs that are FDA approved for the treatment of dermatomyositis (DM), even though multiple clinical trials are ongoing to evaluate safety and efficacy of novel therapeutics in DM. The purpose of this review is to highlight the biological plausibility, existing clinical evidence as well as completed and ongoing clinical trials for various drugs in pipeline for development for use in dermatomyositis.

AREAS COVERED

The drugs with the strongest evidence have been included in this review with a focus on the mechanism of their action pertaining to the disease process, clinical studies including completed and ongoing trials. With better understanding of the underlying pathophysiologic process, there are new molecular targets that have been identified that can be targeted by these novel drugs, predominantly biologic drugs.

EXPERT OPINION

There are various drugs being evaluated in phase II/III clinical trials that hold promise in DM. At the forefront of these are immunoglobulin, Lenabasum, and Abatacept for which phase III clinical trials are ongoing. In addition, promising clinical studies are ongoing or reported for KZR-616, anti-B cell therapy, anti-interferon drugs, and Repository Corticotrophin Injection (RCI).

Anti-TIF1-γ autoantibodies: warning lights of a tumour autoantigen

Anti-transcription intermediary factor 1 (TIF1)-γ autoantibodies are robustly linked with cancer-associated DM in adults. This review aims to give an overview of the physiological context of TIF1-γ and to determine whether there is a pathophysiological link between anti-TIF1-γ autoantibodies and the occurrence of cancer. Detection of anti-TIF1-γ autoantibodies has a high sensitivity and specificity for cancer-associated DM in adults and is therefore useful for both diagnosis and cancer risk stratification. The function of the autoantigen, TIF1-γ, may provide insight into the mechanism behind this association. TIF1-γ is a ubiquitously present protein involved in various biological pathways, including TGF-β signalling. In cancer, it can act either as a tumour suppressor or promoter, depending on the cellular context and cancer stage. Evolving data provide pathophysiological insights, linking anti-TIF1-γ autoantibodies to both the anti-tumour response and to muscle and skin damage. TIF1-γ expression is increased in muscle and skin tissue of patients with DM. Mutations or loss-of-heterozygosity in TIF1-γ alleles in malignant tissue may result in the expression of tumour-specific neo-antigens stimulating autoantibody production. The newly formed autoantibodies are hypothesized to cross-react with antigens in muscle and skin, driving the development of DM. Based on the current evidence, anti-TIF1-γ autoantibodies should be considered warning lights of a potential tumour autoantigen and should alert the physician to the possibility of an underlying cancer.

Interferon-signature in idiopathic inflammatory myopathies

PURPOSE OF REVIEW

The present review describes the interferon (IFN)-signature currently emerging as a tool for the diagnosis of idiopathic inflammatory myopathies (IIMs), and aims at presenting the interests and limitations of this recent tool for the clinics and the research.

RECENT FINDINGS

Recent in-vivo and in-vitro transcriptomic studies have evidenced the involvement of IFNs in the pathogenesis of IIMs. A correlation between the IFN-signature and the clinical severity of IIMs has been established. Moreover, studies pointed out differences in the IFN-signature regarding the IIM subgroup (dermatomyositis, polymyositis, inclusion body myositis, anti-synthetase syndrome, immuno-mediated necrotizing myopathies), raising the hypothesis of several pathogenic processes in IIMs.

SUMMARY

IIM pathogenesis remains partially understood. IFN-signature represents one of the main recent advances in the field. IFN-signature was identified thanks to transcriptomic analyses of tissues or cells from IIM patients (muscle, skin, blood cells, muscle cells) and should allow to establish new diagnosis and better monitoring of IIM patients. It also provides a tool for investigation of IIM pathogenesis. Nevertheless, IFN-signature still requires accurate definition in order to standardize its use, notably in the clinical practice.

Using peripheral blood immune signatures to stratify patients with adult and juvenile inflammatory myopathies

OBJECTIVE

The inflammatory idiopathic myopathies (IIM) are a group of rare autoimmune diseases defined by muscle weakness and characterized by pro-inflammatory infiltrates in muscle. Little is known about the immunological profile in peripheral blood of these patients and how this relates to IIM subtypes. This study aimed to stratify adult and juvenile-onset IIM patients according to immune cell profile.

METHODS

Peripheral blood mononuclear cells from 44 patients with adult myositis (AM), 15 adolescent-onset juvenile dermatomyositis (a-JDM), and 40 age-matched healthy controls were analysed by flow cytometry to quantify 33 immune cell subsets. Adult myositis patients were grouped according to myositis subtype; DM and polymyositis; and also autoantibody specificity. Disease activity was determined by the myositis disease activity assessment tool and clinicians' decision on treatment.

RESULTS

Unique immune signatures were identified for DM, polymyositis and a-JDM compared with healthy controls. DM patients had a T-cell signature comprising increased CD4+ and TH17 cell frequencies and increased immune cell expression of IL-6. Polymyositis patients had a B-cell signature with reduced memory B cells. A-JDM had decreased naïve B cells and increased CD4+T cells. All patient groups had decreased CD8+central memory T-cell frequencies. The distinct immune signatures were also seen when adult myositis patients were stratified according to auto-antibody expression; patients with anti-synthetase-antibodies had reduced memory B cells and patients with autoimmune rheumatic disease overlap had an elevated Th17 profile.

CONCLUSION

Unique immune signatures were associated with adult vs juvenile disease. The Th17 signature in DM patients supports the potential use of IL-17 inhibitors in treatment of IIMs.

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.

Serum-soluble TRAIL: a potential biomarker for disease activity in myositis patients

OBJECTIVES

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a member of the TNF super-family, which is involved in the regulation of immune response and pathogenesis of autoimmune diseases, including polymyositis (PM) and dermatomyositis (DM). In this study, we examined the level and origin of serum-soluble TRAIL (sTRAIL) in patients with PM and DM and analyzed its association with disease activity and clinical features.

METHOD

11 PM patients, 33 DM patients, and 20 healthy controls were enrolled in this study. Clinical features were recorded when admitted, and disease activity was evaluated by myositis disease activity assessment visual analogue scale (MYOACT). TRAIL expression in muscle tissues was detected by immunohistochemistry. Serum sTRAIL levels were measured by enzyme-linked immunosorbent assay. The expression of membrane TRAIL (mTRAIL) and its receptors, including DR4 and DR5, on circulating T cells was analyzed by flow cytometry.

RESULTS

TRAIL was expressed in infiltrated inflammatory cells in muscle tissues from patients. The serum sTRAIL level was markedly increased in patients and was positively correlated with the disease activity. Serum sTRAIL was decreased after therapy in patients and was specifically higher in patients with dysphagia, but lower in patients with autoantibody Jo-1 positive. The frequency of mTRAIL and its receptors on circulating T cells from patients were significantly elevated than that from healthy controls.

CONCLUSIONS

The serum sTRAIL could be a biomarker for evaluating the disease activity of PM and DM, and targeting the generation of TRAIL in T cells might be a potential approach in the treatment of PM and DM.

Treatment of inflammatory myopathies

INTRODUCTION

The idiopathic inflammatory myopathies (IIM) dermatomyositis (DM) and polymyositis (PM) are chronic diseases affecting the striated muscles with variable involvement of other organs. Glucocorticoids are considered the cornerstone of treatment, but some patients require adjunctive immunosuppressive agents because of insufficient response to glucocorticoids, flares upon glucocorticoid tapering, or glucocorticoid-related adverse events. Areas covered: The aim of this article was to review (PubMed search until February 2018) the evidence on established and new therapies derived from randomized controlled trials (RCTs) on adult DM and PM. In addition, key data from open-label trials, case reports, and abstracts were included where data from RCT were lacking. Expert commentary: Numerous synthetic and biological immunosuppressive agents are currently available to treat the IIM, sometimes in combination. The choice of the specific medication in the individual patient depends upon the disease phenotype and patient's characteristics. Exercise improves muscle performance without causing disease flares and should be an integral part of the treatment of the IIM. Prompt diagnosis and treatment can lead to better outcome.

Exacerbation of Murine Experimental Autoimmune Myositis by Toll-Like Receptor 7/8

OBJECTIVE

Toll-like receptor 7 (TLR-7), TLR-8, and interferon (IFN)-induced genes are expressed in patients with idiopathic inflammatory myositis. This study was undertaken to investigate whether their activation influences the natural history of the disease.

METHODS

Experimental autoimmune myositis was induced in mice by injection of the amino-terminal portion of the murine histidyl-transfer RNA synthetase (HisRS). Disease was compared in the presence or the absence of the TLR-7/8 agonist R-848 in wild-type mice and in mice that fail to express the IFNα/β receptor (IFNα/βR-null mice).

RESULTS

Experimental autoimmune myositis induced by a single intramuscular immunization with HisRS spontaneously abated after 7-8 weeks. In contrast, levels of anti-HisRS autoantibodies, endomysial/perimysial leukocyte infiltration, and myofiber regeneration persisted at the end of the follow-up period (22 weeks after immunization) in mice immunized with HisRS in the presence of R-848. Myofiber major histocompatibility complex (MHC) class I molecules were detectable only in mice immunized with both HisRS and R-848. MHC up-regulation occurred early and in muscles that were not directly injected with HisRS. Muscle MHC expression paralleled with leukocyte infiltration. MHC class I molecules were selectively up-regulated in myotubes challenged with R-848 in vitro. Type I IFN was necessary for the prolonged autoantibody response and for the spreading of the autoimmune response, as demonstrated using IFNα/βR-null mice. Muscle infiltration was maintained in the injected muscle up to the end of the follow-up period.

CONCLUSION

TLR-7/8 activation is necessary to induce and maintain a systemic autoimmune response targeting the skeletal muscle. This experimental autoimmune myositis model reproduces many characteristics of human idiopathic inflammatory myopathies and may represent a tool for preclinical studies.

Current Classification and Management of Inflammatory Myopathies

Inflammatory disorders of the skeletal muscle include polymyositis (PM), dermatomyositis (DM), (immune mediated) necrotizing myopathy (NM), overlap syndrome with myositis (overlap myositis, OM) including anti-synthetase syndrome (ASS), and inclusion body myositis (IBM). Whereas DM occurs in children and adults, all other forms of myositis mostly develop in middle aged individuals. Apart from a slowly progressive, chronic disease course in IBM, patients with myositis typically present with a subacute onset of weakness of arms and legs, often associated with pain and clearly elevated creatine kinase in the serum. PM, DM and most patients with NM and OM usually respond to immunosuppressive therapy, whereas IBM is largely refractory to treatment. The diagnosis of myositis requires careful and combinatorial assessment of (1) clinical symptoms including pattern of weakness and paraclinical tests such as MRI of the muscle and electromyography (EMG), (2) broad analysis of auto-antibodies associated with myositis, and (3) detailed histopathological work-up of a skeletal muscle biopsy. This review provides a comprehensive overview of the current classification, diagnostic pathway, treatment regimen and pathomechanistic understanding of myositis.

Physical exercise among patients with systemic autoimmune myopathies

Systemic autoimmune myopathies (SAMs) are a heterogeneous group of rare systemic autoimmune diseases that primarily affect skeletal muscles. Patients with SAMs show progressive skeletal muscle weakness and consequent functional disabilities, low health quality, and sedentary lifestyles. In this context, exercise training emerges as a non-pharmacological therapy to improve muscle strength and function as well as the clinical aspects of these diseases. Because many have feared that physical exercise exacerbates inflammation and consequently worsens the clinical manifestations of SAMs, it is necessary to evaluate the possible benefits and safety of exercise training among these patients. The present study systematically reviews the evidence associated with physical training among patients with SAMs.

Aminoquinoline antimalarial therapy in dermatomyositis-are we missing opportunities with respect to comorbidities and modulation of extracutaneous disease activity?

It is now widely accepted that long-term aminoquinoline antimalarial therapy with hydroxychloroquine (HCQ) can mitigate one of the most important comorbidities of systemic lupus erythematosus (LE)-atherosclerotic cardiovascular disease (ASCVD). Increasing evidence suggests that idiopathic inflammatory myopathy (IIM) patients have a risk for ASCVD comorbidity that is similar to that of systemic LE. I would like to explore the primary hypothesis that long-term HCQ therapy could provide those with IIM, especially dermatomyositis (DM) patients, an ASCVD comorbidity benefit similar to that of systemic LE. In addition, while HCQ is known to have clinical benefits for the cutaneous manifestations of DM, I would also like to explore the secondary hypothesis that HCQ might have steroid-sparing effects on one or more of the systemic manifestations of DM.

Focal myositis: New insights on diagnosis and pathology

OBJECTIVE

To better define in a cohort study the clinical and pathologic features of focal myositis (FM).

METHODS

With the use of the usual clinicopathologic definition, each confirmed case of FM in the Lyon University Hospital's myopathologic database between 2000 and 2016 was retrieved. Clinical, pathologic, imaging, serologic, and therapeutic data were collected. When data were missing but feasible, appropriate pathologic analyses were performed.

RESULTS

Of the 924 patients included in the database, 37 (4%) had confirmed FM (14 female, 23 male patients). The main symptoms were pain (n = 30, 81%), muscular mass (n = 16, 43%), erythema at the site of FM (n = 12, 32%), and fever (n = 9, 24%). Serum creatine kinase was normal in most patients (81%); serum immune abnormalities were frequent (inflammatory syndrome in sera [39%], dysglobulinemia [52%], and anti-nuclear antibody positivity [29%]). In addition to confirming previously reported findings, pathologic analyses found significant rates of vasculitis (68%) and fasciitis (73%). Here, FM appeared frequently to be associated with other diseases such as immune-mediated inflammatory disease (IMID; 32%), neoplasia (24%), and radiculopathy (11%). Regarding outcomes, 64% of the cases had received immunosuppressive drugs, and the relapse rate was 41%.

CONCLUSION

The present study suggests that FM is not as innocuous as previously believed, particularly considering the associated disorders. Notably, patients with FM should receive careful IMID and neoplasia screening.

Increased Levels of Soluble Programmed Death Ligand 1 Associate with Malignancy in Patients with Dermatomyositis

Objective.

To investigate the levels of soluble programmed death ligand 1 (sPD-L1) and evaluate its association with malignancy in patients with dermatomyositis (DM).

Methods.

Levels of sPD-L1 were measured in serum from 88 DM patients without malignancies (sDM), 40 with cancer-related DM (CRDM), and 30 healthy controls (HC) using ELISA. The CRDM subjects were divided into new-onset cancers (nCRDM) and stable cancers (sCRDM). Receiver-operating characteristic (ROC) curve analysis was performed to determine the cutoff sPD-L1 value that distinguished patients with nCRDM from those who were sDM. Serum antitranscriptional intermediary factor 1-γ (TIF1-γ) antibodies were detected using immunoblot, and the diagnostic values for malignancy were compared with sPD-L1 levels in patients with DM.

Results.

Serum sPD-L1 levels were significantly higher in sDM [median 12.3 ng/ml, interquartile range (IQR) 8.4–16.2] than in HC (median 1.3 ng/ml, IQR 0.4–2.2, p = 0.0001). Extremely high sPD-L1 levels were seen in nCRDM (median 18.5 ng/ml, IQR 13.8–22.4), much higher than those in sCRDM (median 8.5 ng/ml, IQR 6.8–11.8, p = 0.0001). The sPD-L1 levels in 4 patients with nCRDM decreased after curative cancer treatment (p = 0.013). ROC curve analysis revealed that the sPD-L1 value distinguishing nCRDM from sDM was 16.1 ng/ml, with an area under the curve value of 0.72 ± 0.04 (p = 0.0001). The combination of sPD-L1 and anti-TIF1-γ antibodies yielded greater specificity and positive predictive value in diagnosing cancer, reaching values of 95% and 70%, respectively.

Conclusion.

Serum sPD-L1 levels increased significantly in sDM, and markedly high sPD-L1 levels could be a diagnostic indicator for malignancies in patients with DM, especially in those with anti-TIF1-γ antibodies.