Autoantibody levels in myositis patients correlate with clinical response during B cell depletion with rituximab

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.

Autoantibodies against the melanoma differentiation-associated protein 5 in patients with dermatomyositis target the helicase domains

OBJECTIVES

Clinical observations in patients with dermatomyositis (DM) and autoantibodies against the melanoma differentiation-associated protein 5 (MDA5) suggest that the autoantibodies contribute to the pathogenesis of MDA5(+) DM. To gain insight into the role of the anti-MDA5 autoantibodies, we aimed to identify their binding sites on the different domains of the MDA5 protein.

METHODS

We developed an in-house ELISA to assess the reactivity against the MDA5 domains (conformational epitopes) in plasma (n = 8) and serum (n = 24) samples from MDA5(+) patients with varying clinical manifestations and disease outcomes. The reactivities were also assessed using western blot (linearized epitopes). An ELISA-based depletion assay was developed to assess cross-reactivity among the different MDA5 domains.

RESULTS

All eight plasma samples consistently showed reactivity towards conformational and linearized epitopes on the helicase domains of the MDA5 protein. The ELISA-based depletion assay suggests that anti-MDA5 autoantibodies specifically target each of the three helicase domains. Twenty-two of the 24 serum samples showed reactivity in the in-house ELISA and all 22 displayed reactivity towards the helicase domains of the MDA5 protein.

CONCLUSIONS

Our data revealed that the main immunogenic targets of anti-MDA5 autoantibodies from MDA5(+) patients are the helicase domains. Considering that the helicase domains are responsible for the enzymatic activity and subsequent triggering of an inflammatory response, our findings suggest that binding of anti-MDA5 autoantibodies could alter the canonical activity of the MDA5 protein and potentially affect the downstream induction of a pro-inflammatory cascade.

B cell receptor repertoire abnormalities in autoimmune disease

B cells play a crucial role in the immune response and contribute to various autoimmune diseases. Recent studies have revealed abnormalities in the B cell receptor (BCR) repertoire of patients with autoimmune diseases, with distinct features observed among different diseases and B cell subsets. Classically, BCR repertoire was used as an identifier of distinct antigen-specific clonotypes, but the recent advancement of analyzing large-scale repertoire has enabled us to use it as a tool for characterizing cellular biology. In this review, we provide an overview of the BCR repertoire in autoimmune diseases incorporating insights from our latest research findings. In systemic lupus erythematosus (SLE), we observed a significant skew in the usage of VDJ genes, particularly in CD27+IgD+ unswitched memory B cells and plasmablasts. Notably, autoreactive clones within unswitched memory B cells were found to be increased and strongly associated with disease activity, underscoring the clinical significance of this subset. Similarly, various abnormalities in the BCR repertoire have been reported in other autoimmune diseases such as rheumatoid arthritis. Thus, BCR repertoire analysis holds potential for enhancing our understanding of the underlying mechanisms involved in autoimmune diseases. Moreover, it has the potential to predict treatment effects and identify therapeutic targets in autoimmune diseases.

TCRβ clones in muscle tissue share structural features in patients with idiopathic inflammatory myopathy and are associated with disease activity

Objectives

To characterize the T cell receptor (TCRβ) repertoire in peripheral blood and muscle tissues of treatment naïve patients with newly diagnosed idiopathic inflammatory myopathies (IIMs).

Methods

High throughput RNA sequencing of the TCRβ chain was performed in peripheral blood and muscle tissue in twenty newly-diagnosed treatment-naïve IIM patients (9 DM, 5 NM/OM, 5 IMNM and 1 ASyS) and healthy controls. Results thereof were correlated with markers of disease activity.

Results

Muscle tissue of IIM patients shows more expansion of TCRβ clones and decreased diversity when compared to peripheral blood of IIM as well as healthy controls (both p=0.0001). Several expanded TCRβ clones in muscle are tissue restricted and cannot be retrieved in peripheral blood. These clones have significantly longer CDR3 regions when compared to clones (also) found in circulation (p=0.0002), while their CDR3 region is more hydrophobic (p<0.01). Network analysis shows that clonal TCRβ signatures are shared between patients. Increased clonal expansion in muscle tissue is significantly correlated with increased CK levels (p=0.03), while it tends to correlate with decreased muscle strength (p=0.08).

Conclusion

Network analysis of clones in muscle of IIM patients shows shared clusters of sequences across patients. Muscle-restricted CDR3 TCRβ clones show specific structural features in their T cell receptor. Our results indicate that clonal TCRβ expansion in muscle tissue might be associated with disease activity. Collectively, these findings support a role for specific clonal T cell responses in muscle tissue in the pathogenesis of the IIM subtypes studied.

Distinct HLA associations with autoantibody-defined subgroups in idiopathic inflammatory myopathies

BACKGROUND

In patients with idiopathic inflammatory myopathies (IIM), autoantibodies are associated with specific clinical phenotypes suggesting a pathogenic role of adaptive immunity. We explored if autoantibody profiles are associated with specific HLA genetic variants and clinical manifestations in IIM.

METHODS

We included 1348 IIM patients and determined the occurrence of 14 myositis-specific or -associated autoantibodies. We used unsupervised cluster analysis to identify autoantibody-defined subgroups and logistic regression to estimate associations with clinical manifestations, HLA-DRB1, HLA-DQA1, HLA-DQB1 alleles, and amino acids imputed from genetic information of HLA class II and I molecules.

FINDINGS

We identified eight subgroups with the following dominant autoantibodies: anti-Ro52, -U1RNP, -PM/Scl, -Mi2, -Jo1, -Jo1/Ro52, -TIF1γ or negative for all analysed autoantibodies. Associations with HLA-DRB1∗11, HLA-DRB1∗15, HLA-DQA1∗03, and HLA-DQB1∗03 were present in the anti-U1RNP-dominated subgroup. HLA-DRB1∗03, HLA-DQA1∗05, and HLA-DQB1∗02 alleles were overrepresented in the anti-PM/Scl and anti-Jo1/Ro52-dominated subgroups. HLA-DRB1∗16, HLA-DRB1∗07 alleles were most frequent in anti-Mi2 and HLA-DRB1∗01 and HLA-DRB1∗07 alleles in the anti-TIF1γ subgroup. The HLA-DRB1∗13, HLA-DQA1∗01 and HLA-DQB1∗06 alleles were overrepresented in the negative subgroup. Significant signals from variations in class I molecules were detected in the subgroups dominated by anti-Mi2, anti-Jo1/Ro52, anti-TIF1γ, and the negative subgroup.

INTERPRETATION

Distinct HLA class II and I associations were observed for almost all autoantibody-defined subgroups. The associations support autoantibody profiles use for classifying IIM which would likely reflect underlying pathogenic mechanisms better than classifications based on clinical symptoms and/or histopathological features.

FUNDING

See a detailed list of funding bodies in the Acknowledgements section at the end of the manuscript.

Anti-Jo-1 autoantibodies: biomarkers of severity and evolution of the disease in antisynthetase syndrome

BACKGROUND

Anti-Jo-1 autoantibodies represent essential markers in the diagnosis of antisynthetase syndrome (ASS). In this retrospective study, we aimed to investigate whether their concentrations and fluctuations could both respectively reflect the severity and evolution of ASS.

METHODS

Between 2015 and 2020, clinical and biological features of ASS patients with at least one positive measure of anti-Jo-1 autoantibody were collected. At each serum sampling, we assessed myositis activity by using the Myositis Intention to Treat Activities Index (MITAX) and compared anti-Jo-1 concentrations with ASS severity, anti-Jo-1 concentrations between patients with and without active disease, and changes in anti-Jo-1 concentrations with disease activity.

RESULTS

Forty-eight patients with ASS had at least one positive determination of anti-Jo-1 concentration. Among them, twenty-nine patients had at least two determinations of anti-Jo-1 autoantibody in their follow-up. We showed that these autoantibody concentrations were significantly correlated with MITAX (r = 0.4, p = 0.03) and creatine kinase concentration (r = 0.34, p = 0.002) and that they were significantly higher in patients with active disease than in those with inactive disease (91.7 IU/L vs 44.4 IU/L, p = 0.016). During follow-up, we found a significant correlation between fluctuations of anti-Jo-1 autoantibody concentrations and MITAX score (r = 0.7, p < 0.0001).

CONCLUSION

Our results suggest that anti-Jo-1 autoantibody concentration could be a predictive marker of the severity and evolution of ASS and show that their quantification could represent a precious tool for disease monitoring and for improving the therapeutic management of ASS patients.

B-cell receptor profiling before and after IVIG monotherapy in newly diagnosed idiopathic inflammatory myopathies

OBJECTIVE

To unravel B-cell receptor (BcR) characteristics in muscle tissues and peripheral blood and gain more insight into BcR repertoire changes in peripheral blood in idiopathic inflammatory myopathies (IIMs), and study how this correlates to the clinical response to IVIG.

METHODS

Nineteen treatment-naive patients with newly diagnosed IIM were prospectively treated with IVIG monotherapy. RNA-based BcR repertoire sequencing was performed in muscle biopsies collected before, and in peripheral blood (PB) collected before and nine weeks after IVIG treatment. Results were correlated to patients' clinical improvement based on the total improvement score (TIS).

RESULTS

Prior to IVIG treatment, BcR clones found in muscle tissue could be retrieved in peripheral blood. Nine weeks after IVIG treatment, new patient-specific dominant BcR clones appeared in peripheral blood while pre-treatment dominant BcR clones disappeared. The cumulative frequency of all dominant BcR clones before treatment was significantly higher in individuals who responded to IVIG compared with those who did not respond to IVIG, and correlated with a higher CK. During follow-up, a decrease in the cumulative frequency of all dominant clones correlated with a higher TIS.

CONCLUSION

In treatment-naive patients with newly diagnosed IIM, muscle tissue and peripheral blood share expanded BcR clones. In our study a higher cumulative frequency of dominant BcR clones in blood before treatment was associated with a higher CK and better treatment response, suggesting that response to IVIG may depend on the composition of the pre-treatment BcR repertoire.

Comparison of Muscle Biopsy Features with Myositis Autoantibodies in Inflammatory Myopathies: A Pilot Experience

Background

Idiopathic inflammatory myopathies (IIM), also called autoimmune myositis, are heterogeneous. These include dermatomyositis (DM), inclusion body myositis, immune mediated necrotizing myopathy (IMNM), anti-synthetase syndrome (ASS), and overlap polymyositis. Classification of IIM has evolved from clinical to clinico-pathologic to the recent clinico-sero-pathologic with the discovery of myositis-specific antibodies (MSA) and myositis-associated antibodies. The various antibodies have shown association with specific phenotypes.

Objective

To analyze muscle biopsy features with respect to each MSA and MAA to understand the frequency of findings in each entity.

Materials and Methods

Biopsy-proven cases of IIM where myositis profile was available were included in the study after obtaining Institutional Ethics Committee (IEC) approval. In addition to the stains and enzyme histochemistry, immunohistochemistry with MHC class I and II and MxA was performed. Features like perifascicular atrophy, perifascicular necrosis, scattered necrosis, inflammation, etc. were analyzed. Myositis profile was performed by line-blot technique using a 16-antigen panel. Cases were divided into different autoantibody subgroups. Various clinical, demographic, and muscle biopsy features were studied with respect to each MSA and MAA.

Results

There were a total of 64 cases. Mi2 (N = 18) was the most common autoantibody. Some of the salient observations included PFA with perivascular inflammation in Mi2; pediatric cases and microinfarcts in NXP2; no PFA or inflammation in MDA5; perifascicular necrosis in JO1; extensive necrosis with sparse inflammation in SRP; more inflammation in overlap myositis; MxA positivity in DM; and absent in ASS.

Conclusion

This is a pilot study documenting differences in biopsy phenotype with each MSA and MAA which is comparable to the literature. These findings can be used to characterize IIM in seronegative biopsies.

Juvenile idiopathic inflammatory myositis: an update on pathophysiology and clinical care

The childhood-onset or juvenile idiopathic inflammatory myopathies (JIIMs) are a heterogenous group of rare and serious autoimmune diseases of children and young people that predominantly affect the muscles and skin but can also involve other organs, including the lungs, gut, joints, heart and central nervous system. Different myositis-specific autoantibodies have been identified that are associated with different muscle biopsy features, as well as with different clinical characteristics, prognoses and treatment responses. Thus, myositis-specific autoantibodies can be used to subset JIIMs into sub-phenotypes; some of these sub-phenotypes parallel disease seen in adults, whereas others are distinct from adult-onset idiopathic inflammatory myopathies. Although treatments and management have much improved over the past decade, evidence is still lacking for many of the current treatments and few validated prognostic biomarkers are available with which to predict response to treatment, comorbidities (such as calcinosis) or outcome. Emerging data on the pathogenesis of the JIIMs are leading to proposals for new trials and tools for monitoring disease.

The role of bDMARDs in idiopathic inflammatory myopathies: A systematic literature review

Idiopathic inflammatory myopathies (IIM) are a group of different conditions typically affecting striate muscle, lung, joints, skin and gastrointestinal tract. Treatment typically relies on glucocorticoids and synthetic immunosuppressants, but the occurrence of refractory, difficult to treat, manifestations, may require more aggressive treatment, borrowed from other autoimmune diseases, including biologic disease modifying drugs (bDMARDs). In this regard, we conducted a systemic literature review in order to depict the current evidence about the use of bDMARDs in IIM. A total of 78 papers, published during the last 21 years, were retrieved. The majority of patients was treated with TNF-α inhibitors, whose effectiveness was assessed particularly in recalcitrant striate muscle, skin and joints involvement. Rituximab, whose evidence is supported by a large number of real-life studies and trials, seems to be an excellent option in case of ILD and anti-synthetase syndrome, while Tocilizumab, despite not meeting primary and secondary endpoints in a recently published clinical trial, proved its effectiveness in rapidly progressing ILD. Similarly, Abatacept, studied in a phase IIb clinical trial with conflicting evidence, was reported to be effective in some case reports of refractory dermatomyositis. Less data exist for anti-IL1 and anti-IL23 agents, which were employed particularly for inclusion body myositis and severe skin disease, respectively. This study provides an organ-focused assessment of bDMARDs in IIM, which display encouraging results in the treatment of refractory subsets of disease.

Autoantigenic properties of the aminoacyl tRNA synthetase family in idiopathic inflammatory myopathies

OBJECTIVES

Autoantibodies are thought to play a key role in the pathogenesis of idiopathic inflammatory myopathies (IIM). However, up to 40% of IIM patients, even those with clinical manifestations of anti-synthetase syndrome (ASSD), test seronegative to known myositis-specific autoantibodies. We hypothesized the existence of new potential autoantigens among human cytoplasmic aminoacyl tRNA synthetases (aaRS) in patients with IIM.

METHODS

Plasma samples from 217 patients with IIM according to 2017 EULAR/ACR criteria, including 50 patients with ASSD, 165 without, and two with unknown ASSD status were identified retrospectively, as well as age and gender-matched sera from 156 population controls, and 219 disease controls. Patients with previously documented ASSD had to test positive for at least one of the five most common anti-aaRS autoantibodies (anti-Jo1, -PL7, -PL12, -EJ, and -OJ) and present with one or more of the following clinical manifestations: interstitial lung disease, myositis, arthritis, Raynaud's phenomenon, fever, or mechanic's hands. Demographics, laboratory, and clinical data of the IIM cohort (ASSD and non-ASSD) were compared. Samples were screened using a multiplex bead array assay for presence of autoantibodies against a panel of 117 recombinant protein variants, representing 33 myositis-related proteins, including all nineteen cytoplasmic aaRS. Prospectively collected clinical data for the IIM cohort were retrieved and compared between groups within the IIM cohort and correlated with the results of the autoantibody screening. Principal component analysis was used to analyze clinical manifestations between ASSD, non-ASSD groups, and individuals with novel anti-aaRS autoantibodies.

RESULTS

We identified reactivity towards 16 aaRS in 72 of the 217 IIM patients. Twelve patients displayed reactivity against nine novel aaRS. The novel autoantibody specificities were detected in four previously seronegative patients for myositis-specific autoantibodies and eight with previously detected myositis-specific autoantibodies. IIM individuals with novel anti-aaRS autoantibodies (n = 12) all had signs of myositis, and they had either muscle weakness and/or muscle enzyme elevation, 2/12 had mechanic's hands, 3/12 had interstitial lung disease, and 2/12 had arthritis. The individuals with novel anti-aaRS and a pathological muscle biopsy all presented widespread up-regulation of major histocompatibility complex class I. The reactivities against novel aaRS could be confirmed in ELISA and western blot. Using the multiplex bead array assay, we could confirm previously known reactivities to four of the most common aaRS (Jo1, PL12, PL7, and EJ (n = 45)) and identified patients positive for anti-Zo, -KS, and -HA (n = 10) that were not previously tested. A low frequency of anti-aaRS autoantibodies was also detected in controls.

CONCLUSION

Our results suggest that most, if not all, cytoplasmic aaRS may become autoantigenic. Autoantibodies against new aaRS may be found in plasma of patients previously classified as seronegative with potential high clinical relevance.

Efficacy and safety of rituximab treatment in patients with idiopathic inflammatory myopathies: A systematic review and meta-analysis

Objective

Idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of autoimmune diseases with various subtypes, myositis-specific antibodies, and affect multiple systems. The treatment of IIMs remains challenging, especially for refractory myositis. In addition to steroids and traditional immunosuppressants, rituximab (RTX), a B cell-depleting monoclonal antibody, is emerging as an alternative treatment for refractory myositis. However, the therapeutic response to RTX remains controversial. This meta-analysis aimed to systematically evaluate the efficacy and safety of RTX in patients with IIMs, excluding sporadic inclusion body myositis.

Methods

PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, and WanFang Data were searched for relevant studies. The overall effective rate, complete response rate, and partial response rate were calculated to assess the efficacy of RTX. The incidences of adverse events, infection, severe adverse events, severe infection, and infusion reactions were collected to evaluate the safety of RTX. Subgroup analyses were performed using IIM subtypes, affected organs, continents, and countries. We also performed a sensitivity analysis to identify the sources of heterogeneity.

Results

A total of 26 studies were included in the quantitative analysis, which showed that 65% (95% confidence interval [CI]: 54%, 75%) of patients with IIMs responded to RTX, 45% (95% CI: 22%, 70%) of patients achieved a complete response, and 39% (95% CI: 26%, 53%) achieved a partial response. Subgroup analyses indicated that the overall efficacy rates in patients with refractory IIMs, dermatomyositis and polymyositis, as well as anti-synthetase syndrome were 62%, 68%, and 62%, respectively. The overall efficacy rates for muscle, lungs, and skin involvement were 59%, 65%, and 81%, respectively. In addition, studies conducted in Germany and the United States showed that patients with IIMs had an excellent response to RTX, with an effective rate of 90% and 77%, respectively. The incidence of severe adverse events and infections was 8% and 2%, respectively.

Conclusion

RTX may be an effective and relatively safe treatment choice in patients with IIMs, especially for refractory cases. However, further verification via randomized controlled trials is warranted.

Indications and Safety of Rituximab in Pediatric Neurology: A 10-Year Retrospective Study

BACKGROUND

RTX is used off-label in several neurological inflammatory diseases in adults children patients. We conducted a study to assess indications and safety of rituximab (RTX) for children and to identify risk factors for early B-cell repopulation.

METHODS

A single-center retrospective study of children treated with RTX for a neurological disease between May 31, 2010, and May 31, 2020, was performed.

RESULTS

A total of 77 children (median age, 8.9 years) were included. RTX was mostly used as second-line therapy in all groups of diseases (68%). Median dose was 1500 mg/m² for each patient. There were 13 clinical relapses (17%), 5 when B-cell depletion was complete. Adverse events were present in 6% of the cases. The factors influencing early B-cell repopulation were the recent infusion of intravenous Ig (P < 0.01) and the administration of less than 1500 mg/m² during the first RTX treatment (P = 0.04). The median time to B-cell repopulation seemed to be shorter (160 vs 186 days) when patients had plasmapheresis even when a 48-hour delay was observed with RTX infusions.

CONCLUSIONS

This study confirms the good tolerance of RTX in the treatment of specific neurological disorders in a pediatric population. It also highlights risk factors for early B-cell repopulation and underlines the importance of B-cell monitoring.

The use of ELISA is comparable to immunoprecipitation in the detection of selected myositis-specific autoantibodies in a European population

Background

The reliable detection of myositis-specific autoantibodies (MSA) provides valuable clinical information regarding prognosis, clinical progression and diagnostic confirmation.

Objectives

To evaluate the reliability of a commercial ELISA immunoassay in detecting myositis-specific autoantibodies in comparison to immunoprecipitation as the reference standard.

Methods

Serum samples were chosen from a biobank of more than 3000 samples. Samples with a confirmed MSA on Immunoprecipitation (n=116) were evaluated in duplicate by ELISA to detect Mi2, MDA5, Jo1, EJ, KS, PL-7 and PL-12 (Medical &amp; Biological Laboratories Co. Ltd, Nagoya, Aichi, Japan). Healthy control samples (n=246) confirmed autoantibody negative by immunoprecipitation were similarly assessed.

Results

There was a very good agreement between ELISA and immunoprecipitation for serum samples containing anti-Mi2, MDA5, Jo1, EJ, KS and PL-7 and PL-12 auto-antibodies. Cohen’s κ values ranged from 0.86-1 for the measured autoantibodies on ELISA.

Conclusion

ELISA was an accurate method for detecting anti-synthetase, anti-Mi2 and anti-MDA5 autoantibodies.

Biomarkers of disease activity in dermatomyositis

PURPOSE OF REVIEW

This review provides updates regarding biomarker studies that address key clinical unmet needs, which relate to the evaluation of the disease activity in patients with dermatomyositis.

RECENT FINDINGS

Increasing evidence supports that the serum levels of dermatomyositis-specific antibodies (DM-MSAs), which include anti-Mi-2, anti-NXP2, anti-MDA5, anti-TNF1-γ, and anti-SAE, are correlated with the disease activity. Moreover, serial measurements of DM-MSA levels may help to predict the disease status. Beyond the MSA, macrophage activation-related biomarker-soluble CD163, CD206, neopterin, and galectin-3/9 are the most currently talked biomarkers for disease activity in dermatomyositis; new circulating T-cell subsets CD4+CXCR5+CCR7loPD-1hi and TIGIT+CD226+ CD4 T cells can potentially harbor biomarkers of disease activity in dermatomyositis. In addition, LDGs and NETs were also shown to be correlated with the disease activities of dermatomyositis.

SUMMARY

Promising candidate biomarkers are now available for evaluating disease activity in dermatomyositis. These biomarkers need external validation in other large cohort studies.

Skeletal muscle provides the immunological micro-milieu for specific plasma cells in anti-synthetase syndrome-associated myositis

Anti-synthetase syndrome (ASyS)-associated myositis is a major subgroup of the idiopathic inflammatory myopathies (IIM) and is characterized by disease chronicity with musculoskeletal, dermatological and pulmonary manifestations. One of eight autoantibodies against the aminoacyl-transferase RNA synthetases (ARS) is detectable in the serum of affected patients. However, disease-specific therapeutic approaches have not yet been established.To obtain a deeper understanding of the underlying pathogenesis and to identify putative therapeutic targets, we comparatively investigated the most common forms of ASyS associated with anti-PL-7, anti-PL-12 and anti-Jo-1. Our cohort consisted of 80 ASyS patients as well as healthy controls (n = 40), diseased controls (n = 40) and non-diseased controls (n = 20). We detected a reduced extent of necrosis and regeneration in muscle biopsies from PL-12⁺ patients compared to Jo-1⁺ patients, while PL-7⁺ patients had higher capillary dropout in biopsies of skeletal muscle. Aside from these subtle alterations, no significant differences between ASyS subgroups were observed. Interestingly, a tissue-specific subpopulation of CD138⁺ plasma cells and CXCL12⁺/CXCL13⁺CD20⁺ B cells common to ASyS myositis were identified. These cells were localized in the endomysium associated with alkaline phosphatase⁺ activated mesenchymal fibroblasts and CD68⁺MHC-II⁺CD169⁺ macrophages. An MHC-I⁺ and MHC-II⁺ MxA negative type II interferon-driven milieu of myofiber activation, topographically restricted to the perifascicular area and the adjacent perimysium, as well as perimysial clusters of T follicular helper cells defined an extra-medullary immunological niche for plasma cells and activated B cells. Consistent with this, proteomic analyses of muscle tissues from ASyS patients demonstrated alterations in antigen processing and presentation. In-depth immunological analyses of peripheral blood supported a B-cell/plasma-cell-driven pathology with a shift towards immature B cells, an increase of B-cell-related cytokines and chemokines, and activation of the complement system. We hypothesize that a B-cell-driven pathology with the presence and persistence of a specific subtype of plasma cells in the skeletal muscle is crucially involved in the self-perpetuating chronicity of ASyS myositis. This work provides the conceptual framework for the application of plasma-cell-targeting therapies in ASyS myositis.

Autoantibodies: Pathogenic or epiphenomenon

Idiopathic inflammatory myopathies (IIM) are heterogeneous autoimmune diseases. There are distinct subgroups, including antisynthetase syndrome, dermatomyositis, polymyositis, immune-mediated necrotizing myopathy, and sporadic inclusion body myositis. In patients with IIM, autoantibodies are present in up to 80% of the patients. These autoantibodies are often characterized as myositis-specific autoantibodies (MSA) or myositis-associated autoantibodies (MAA). The recognition of the importance of autoantibodies, especially MSA, is increasing in recent years. In this chapter, we provide an overview of the MSAs, including some new autoantibodies of interest as they target mainly muscle-specific autoantigen, in clinical classification, the measurement of the disease activity, and a possible role in the pathogenesis in the patients with IIM.

CHD4 orchestrates the symphony of T and B lymphocytes development and a good mediator in preventing from autoimmune disease

Chromodomain helicase DNA binding protein 4 (CHD4) is an ATPase subunit of the nucleosome remodeling and deacetylation complex. It has been implicated in gene transcription, DNA damage repair, maintenance of genome stability, and chromatin assembly. Meanwhile, it is highly related to cell cycle progression and the proceeding of malignancy. Most of the previous studies were focused on the function of CHD4 with tumor cells, cancer stem cells, and cancer cells multidrug resistance. Recently, some researchers have explored the CHD4 functions on the development and differentiation of adaptive immune cells, such as T and B lymphocytes. In this review, we will discuss details of CHD4 in lymphocyte differentiation and development, as well as the critical role of CHD4 in the pathogenesis of the autoimmune disease.

Serum levels of anti-transcriptional intermediary factor 1-γ autoantibody associated with the clinical, pathological characteristics and outcomes of patients with dermatomyositis

OBJECTIVE

To investigate the association of the serum levels of anti-transcriptional intermediary factor 1 (TIF1)-γ autoantibodies with the clinical and pathological characteristics, as well as the prognosis of adult patients with dermatomyositis (DM).

METHODS

Eighty-seven adult DM patients with anti-TIF1-γ autoantibodies positive screened by immunoblotting assay were enrolled in the study. The presence and levels of anti-TIF1-γ autoantibodies were examined through enzyme-linked immunosorbent assay (ELISA). Muscle biopsy specimens were obtained from 52 patients, and immunohistochemistry was performed to visualize major histocompatibility complex (MHC)-I, CD3, CD20 and C5b-9. Muscle biopsy scores and disease activity were evaluated.

RESULTS

A total of 80 patients were positive for anti-TIF1-γ autoantibodies confirmed by ELISA assay, including 30 cancer-associated myositis (CAM) and 50 non-CAM. Serum levels of anti-TIF1-γ autoantibodies did not significantly differ between the CAM and non-CAM groups. The levels of anti-TIF1-γ were associated with disease activity scores. A total of 63.9% of non-CAM patients displayed a classical DM pathological phenotype. Conversely, CAM patients presented with classical DM (25%), immune-mediated necrotizing myopathy (25%), non-specific myositis (32.3%), and normal (18%) phenotypes of muscle biopsy. Anti-TIF1-γ autoantibody levels were positively associated with muscle biopsy total scores, muscle fiber scores and inflammatory infiltration scores in the non-CAM patients but not in the CAM patients. The survival rate of CAM patients presenting with high anti-TIF1-γ autoantibody levels was lower than that of patients with low levels. However, no difference in survival rate was observed in the non-CAM group between high and low autoantibody levels.

CONCLUSION

The distinct associations of anti-TIF1-γ autoantibody levels with disease activity, muscle histopathology damage and outcome indicated that different pathogenesis might be involved in DM with or without cancer.

Pathophysiological Mechanisms and Treatment of Dermatomyositis and Immune Mediated Necrotizing Myopathies: A Focused Review

Idiopathic inflammatory myopathies (IIM), collectively known as myositis, are a composite group of rare autoimmune diseases affecting mostly skeletal muscle, although other organs or tissues may also be involved. The main clinical feature of myositis is subacute, progressive, symmetrical muscle weakness in the proximal arms and legs, whereas subtypes of myositis may also present with extramuscular features, such as skin involvement, arthritis or interstitial lung disease (ILD). Established subgroups of IIM include dermatomyositis (DM), immune-mediated necrotizing myopathy (IMNM), anti-synthetase syndrome (ASyS), overlap myositis (OM) and inclusion body myositis (IBM). Although these subgroups have overlapping clinical features, the widespread variation in the clinical manifestations of IIM suggests different pathophysiological mechanisms. Various components of the immune system are known to be important immunopathogenic pathways in IIM, although the exact pathophysiological mechanisms causing the muscle damage remain unknown. Current treatment, which consists of glucocorticoids and other immunosuppressive or immunomodulating agents, often fails to achieve a sustained beneficial response and is associated with various adverse effects. New therapeutic targets have been identified that may improve outcomes in patients with IIM. A better understanding of the overlapping and diverging pathophysiological mechanisms of the major subgroups of myositis is needed to optimize treatment. The aim of this review is to report on recent advancements regarding DM and IMNM.

Antibody Therapies in Autoimmune Inflammatory Myopathies: Promising Treatment Options

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

Detecting Autoantibodies by Multiparametric Assays: Impact on Prevention, Diagnosis, Monitoring, and Personalized Therapy in Autoimmune Diseases

BACKGROUND

The introduction of multiparametric autoantibody tests has been proposed to improve the accuracy of the immunological diagnosis of autoimmune diseases (AID) and to accelerate time for completing the diagnostic process. Multiplex tests are capable of detecting many autoantibodies in a single run whereas a traditional immunoassay uses a single antigen to detect only a single specificity of autoantibodies. The reasons why multiplex tests could replace conventional immunoassays lie in the evidence that they allow for more efficient handling of large numbers of samples by the laboratory, while ensuring greater diagnostic sensitivity in AID screening.

CONTENT

This review aims to highlight the important role that multiparametric tests could assume when designed for defined profiles they are used not only for diagnostic purposes but also to predict the onset of AID to identify clinical phenotypes and to define prognosis. Furthermore, differences in the antibody profile could identify which subjects will be responsive or not to a specific pharmacological treatment.

SUMMARY

The use of autoantibody profiles, when specifically requested and performed with clinically validated technologies, can represent a significant step toward personalized medicine in autoimmunology.

Autoantibodies in Common Connective Tissue Diseases: A Primer for Laboratory Professionals

Background

Autoimmune connective tissue disorders are a significant health concern throughout the world with an estimated prevalence of 3% to 5%. They are associated with a variety of autoantibodies that play roles in their diagnosis, risk stratification, prognostication, and/or management. While some autoantibodies have been well-characterized for use in clinical laboratories, many more are in the research stage. Rapid transition from research to clinical practice, lack of clinical guidelines, and harmonization across a rapidly growing number of commercially available tests create numerous challenges to clinicians and laboratories.

Content

This article briefly discusses common connective tissue disorders and their association with well-known autoantibodies, describes current methods used in clinical laboratories, and outlines their advantages and limitations in the context of these diseases.

Summary

Understanding the role of specific autoantibodies and various methodologies for autoantibody testing are important for laboratory professionals who may be introducing/repatriating new tests, updating existing tests, or advising clinicians/patients about testing options/results. Collaboration between laboratory professional staff and clinicians, around the advantages and limitations of each methodology, is also important in their appropriate clinical utilization.

Inflammatory myopathies: shedding light on promising agents and combination therapies in clinical trials

INTRODUCTION

Due to new insights into the pathogenesis of inflammatory myopathies - in short myositis - and the urgent need for new treatment options in patients who are refractory to standard therapy, multiple novel drugs have been developed and studied in clinical trials. In light of this exciting development, a critical evaluation of the present data is necessary in order to identify the best pathway to future treatment of inflammatory myopathies.

AREAS COVERED

This review focuses on the current evidence from clinical trials in myositis and encompasses dermatomyositis, polymyositis, necrotizing myopathy, antisynthetase-syndrome, overlap myositis, and inclusion body myositis. The results of studies on new therapeutic agents are summarized, in particular larger cohort studies and randomized trials from recent years. When such data were not available, earlier and smaller representative studies were included instead.

EXPERT OPINION

Current studies in most myositis subtypes have shown positive effects of novel biologicals such as abatacept, sifalimumab, JAK-Inhibitors as well as known agents such as rituximab, but further studies are needed to confirm these observations. In inclusion body myositis, the eagerly awaited recent therapeutic trials have missed their primary endpoints, except for the phase 2 study with rapamycin, which has demonstrated significant improvements in secondary endpoints. Future trials will also need to focus on combination therapies of multiple immunomodulatory agents.

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.

High-Throughput Detection of Autoantigen-Specific B Cells Among Distinct Functional Subsets in Autoimmune Donors

Antigen-specific B cells (ASBCs) can drive autoimmune disease by presenting autoantigen to cognate T cells to drive their activation, proliferation, and effector cell differentiation and/or by differentiating into autoantibody-secreting cells. Autoantibodies are frequently used to predict risk and diagnose several autoimmune diseases. ASBCs can drive type 1 diabetes even when immune tolerance mechanisms block their differentiation into antibody-secreting cells. Furthermore, anti-histidyl tRNA synthetase syndrome patients have expanded IgM⁺ Jo-1-binding B cells, which clinically diagnostic IgG Jo-1 autoantibodies may not fully reflect. Given the potential disconnect between the pathologic function of ASBCs and autoantibody secretion, direct study of ASBCs is a necessary step towards developing better therapies for autoimmune diseases, which often have no available cure. We therefore developed a high-throughput screening pipeline to 1) phenotypically identify specific B cell subsets, 2) expand them in vitro, 3) drive them to secrete BCRs as antibody, and 4) identify wells enriched for ASBCs through ELISA detection of antibody. We tested the capacity of several B cell subset(s) to differentiate into antibody-secreting cells following this robust stimulation. IgM⁺ and/or IgD⁺, CD27^- memory, memory, switched memory, and B_ND B cells secreted B cell receptor (BCR) as antibody following in vitro stimulation, whereas few plasmablasts responded. Bimodal responses were observed across autoimmune donors for IgM⁺ CD21^lo and IgM^- CD21^lo B cells, consistent with documented heterogeneity within the CD21^lo subset. Using this approach, we detected insulin-binding B cell bias towards CD27^- memory and CD27⁺ memory subsets in pre-symptomatic type 1 diabetes donors. We took advantage of routine detection of Jo-1-binding B cells in Jo-1+ anti-histidyl tRNA synthetase syndrome patients to show that Jo-1-binding B cells and total B cells expanded 20-30-fold using this culture system. Overall, these studies highlight technology that is amenable to small numbers of cryopreserved peripheral blood mononuclear cells that enables interrogation of phenotypic and repertoire attributes of ASBCs derived from autoimmune patients.

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.

Jo-1 autoantigen-specific B cells are skewed towards distinct functional B cell subsets in anti-synthetase syndrome patients

Background

Anti-Jo-1 autoantibodies which recognize histidyl-tRNA synthetase identify patients with the rare rheumatologic disease, anti-histidyl-tRNA synthetase syndrome (Jo-1 ARS), a phenotypically distinct subset of idiopathic inflammatory myopathies (IIM). Jo-1-binding B cells (JBCs) are implicated in disease pathogenesis, yet they have not been studied directly. We therefore aimed to characterize JBCs to better understand how they expand and function in Jo-1 ARS.

Methods

We enrolled 10 IIM patients diagnosed with Jo-1 ARS, 4 patients with non-Jo-1 IIM, and 8 age- and sex-matched healthy controls. We phenotypically characterized peripheral blood mononuclear cells (PBMCs) ex vivo using flow cytometry to define the B cell subsets in which JBCs reside. We further tested their ability to differentiate into antibody-secreting cells following stimulation in vitro.

Results

The majority of JBCs were IgM⁺ (not class-switched). Compared to non-JBCs in the same donors, JBCs contained a higher percentage of autoimmune-prone CD21^lo cells and were increased in the CD21^lo IgM⁺ IgD⁻ CD27⁺ memory subset relative to healthy donor B cells. Whereas non-JBCs were present in the anergic B_ND B cell subset, JBCs were nearly absent from this compartment. JBCs were detected among plasmablasts in some donors, but a reduced frequency of JBCs differentiated into CD38^hi24⁻ plasmablasts compared to non-JBCs present in the same wells following in vitro stimulation.

Conclusions

JBCs are enriched for autoimmune-prone CD21^lo B cells, some of which exhibit a memory phenotype in the peripheral repertoire of Jo-1 ARS patients. JBCs undergo limited class switch and show reduced capacity to differentiate into antibody-secreting cells. This suggests complex B cell biology exists beyond class-switched cells that differentiate to secrete anti-Jo-1 autoantibody (i.e., what is captured through serum autoantibody studies). New Jo-1 ARS therapies should thus ideally target non-class-switched JBCs in addition to those that have undergone IgG class-switching to most effectively block cross-talk with autoreactive T cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-020-02412-8.

Factors associated with treatment response in patients with idiopathic inflammatory myopathies. A registry-based study

Objective

To identify predictors of response to immunosuppressive therapy after 1 year, with a focus on autoantibodies, in patients newly diagnosed with idiopathic inflammatory myopathies (IIM) followed longitudinally in an electronic registry.

Methods

We assessed the association between autoantibody‐defined groups and improvement according to American College of Rheumatology/European Alliance of Associations for Rheumatology 2016 response criteria.

Results

We identified 156 patients; of those, 111 (71%) were positive for any autoantibody tested, 90% received glucocorticoid treatment at baseline, and 78% received immunosuppressive drugs at some follow‐up point. After 1 year from the index date, the overall median improvement score was 27.5 (interquartile range 10–51). No differences were observed in the total improvement score between the autoantibody‐defined groups. Overall, 62% of patients (n = 96) showed a minimal response, 38% (n = 60) achieved a moderate response, and 19% (n = 30) achieved a major response. Regarding the different levels of response, dermatomyositis‐specific autoantibodies were associated with a moderate response versus the seronegative group (reference), odds ratio 4.12 (95% confidence interval 1.2–16.5). In addition, dysphagia, time from symptom onset to diagnosis, and initial glucocorticoid dose were significant predictors of response after 1 year of follow‐up.

Conclusion

Patients with DM‐specific autoantibodies achieved better levels of response compared to other autoantibody‐defined groups. Dysphagia, a shorter time span from symptom onset to diagnosis, and intensive initial immunosuppressive treatment were associated with a higher response rate after 1 year of pharmacologic treatment from the index date, regardless of autoantibody status.

Efficacy and Safety of Rituximab in Korean Patients with Refractory Inflammatory Myopathies

BACKGROUND

Rituximab (RTX), a monoclonal antibody that selectively binds to CD20+ B cells, showed favorable outcomes in patients with idiopathic inflammatory myopathies (IIM) in small case series, but the evidence is still not enough. Our goal was to determine the efficacy and safety of RTX for Korean patients with refractory IIM.

METHODS

We retrospectively analyzed the medical records of 16 patients with refractory IIM treated with RTX in seven tertiary rheumatology clinics in the Korea. The efficacy of RTX was evaluated with the improvement of serum creatine phosphokinase (CPK) level and physician's global assessment (PGA), and daily corticosteroid dose reduction. A > 25% decrease in CPK level, corticosteroid dose, or PGA was considered significant. A complete response (CR) was designated by meeting three efficacy criteria and a partial response (PR) by only two criteria.

RESULTS

Sixteen patients with IIM were evaluated (13 female; median age, 51.8 years). All patients had received at least one conventional immunosuppressive agent (median, 3.6 [2.0-5.0]) and concomitant corticosteroids. The median CPK level and median dose of prednisolone was 421.0 units/L and 20.0 mg/day respectively. Eleven patients were treated with intravenous immunoglobulin. Seven patients received 2,000 mg of RTX and the others received lower dose. Twenty-four weeks after RTX treatment, 11 patients achieved a > 25% reduction in corticosteroid dose and CPK levels, and nine showed improved PGA. The overall response rate was 68.8% (11 patients). At the end of follow-up (median 24 weeks), 12 (75.0%) patients responded overall: four (25.0%) and eight (50.0%) patients achieved CR and PR, respectively. Baseline muscle enzyme levels were higher in responders than non-responders, but disease duration, RTX dose, ESR and serum CRP were not significantly different between the two groups. The rate of adverse event was 25.4/1,000 person-years.

CONCLUSION

RTX could be an effective and relatively safe therapeutic option in patients with refractory IIM.

Line blot immunoassays in idiopathic inflammatory myopathies: retrospective review of diagnostic accuracy and factors predicting true positive results

Background

Line blot immunoassays (LIA) for myositis-specific (MSA) and myositis-associated (MAA) autoantibodies have become commercially available. In the largest study of this kind, we evaluated the clinical performance of a widely used LIA for MSAs and MAAs.

Methods

Adults tested for MSA/MAA by LIA at a tertiary myositis centre (January 2016–July 2018) were identified. According to expert-defined diagnoses, true and false positive rates were calculated for strongly and weakly positive autoantibody results within three cohorts: idiopathic inflammatory myopathy (IIM), connective tissue disease (CTD) without myositis, and non-CTD/IIM. Factors associated with true positivity were determined.

Results

We analysed 342 cases. 67 (19.6%) had IIM, in whom 71 autoantibodies were detected (50 strong positives [70.4%], 21 weak positives [29.6%]). Of the strong positives, 48/50 (96.0%; 19 MSAs, 29 MAAs) were deemed true positives. Of the weak positives, 15/21 (71.4%; 3 MSAs, 12 MAAs) were deemed true positives.

In CTD without myositis cases (n = 120), 31/61 (51.0%; 5 MSAs, 26 MAAs) autoantibodies were strongly positive, with 24/31 (77.4%; 0 MSAs, 24 MAAs) true positives. 30/61 (49.2%; 13 MSAs, 17 MAAs) were weakly positive, with 16/30 (53.3%; 0 MSAs, 16 MAAs) true positives. In non-CTD/IIM cases (n = 155), all 24 MSAs and 22 MAAs were false positives; these results included 17 (37.0%; 7 MSAs, 10 MAAs) strong positives.

Individual autoantibody specificities were > 98.2 and > 97.5% for weakly and strongly positive results, respectively. True positivity was associated with high pre-test for IIM (odds ratio 50.8, 95% CI 13.7–189.2, p < 0.001) and strong positive (versus weak positive) results (4.4, 2.3–8.3, p < 0.001).

Conclusions

We demonstrated the high specificity of a myositis LIA in a clinical setting. However, a significant burden of false positive results was evident in those with a low pre-test likelihood of IIM and for weakly positive autoantibodies.

Factors associated with refractory autoimmune necrotizing myopathy with anti-signal recognition particle antibodies

Background

Autoimmune necrotizing myopathy with anti-signal recognition particle antibodies (ANM-SRP) is regarded as refractory myositis, whereby some patients respond poorly to conventional immunosuppression and require B cell depletion treatment. This study aimed to evaluate factors associated with refractory ANM-SRP.

Results

Clinical and pathological data from 48 patients with ANM-SRP were collected. We followed up clinical symptoms and image changes over 12 months. Univariate and multivariate analyses were undertaken to determine the associations between variables of interest and poor response to therapy. Refractory ANM-SRP appeared in 32.5% of patients who showed no or minimal improvement after 12 months of steroid therapy. The clinical risk factors for refractory patients were being male (OR, 19.57; P < 0.001), severe muscle weakness (OR, 7.51; P < 0.001) and concurrent interstitial lung disease (OR, 39.70; P < 0.001). The imaging refractory-related factor was the fatty infiltration rate of thigh muscles over 3 months (P = 0.022) and the pathological factor associated with refractory ANM-SRP was the high expression of B cell activating factor receptor (BAFF-R) in muscle (P = 0.036).

Conclusion

Being male, severe muscle weakness, concurrent interstitial lung disease, quick development of muscle fatty infiltration and more BAFF-R and B lymphocyte infiltration in muscle indicate a poor response to immunosuppressive therapy in patients with ANM-SRP.

New insights into the treatment of myositis

The myositis syndromes include polymyositis, dermatomyositis (DM), necrotizing myopathy, inclusion body myositis (IBM), antisynthetase syndrome and overlap syndromes with myositis. These syndromes mostly occur in middle-aged patients, while juvenile DM occurs in children and adolescents. Patients mostly show a subacute weakness and myalgia in the upper and lower limbs, the diagnosis is based upon these clinical findings in combination with muscle biopsy results and specific serum autoantibodies. In recent years, research achieved a better understanding about the molecular mechanism underlying the myositis syndromes, as well as disease progress and extramuscular organ manifestations, such as interstitial lung disease and association with neoplasias. Treatment mainly consists of glucocorticosteroids and immunosuppressants. IBM is usually refractory to treatments. This review provides an overview of the current standards of treatment and new treatment options like monoclonal antibodies and new molecular therapies and their first results from clinical trials.

More prominent muscle involvement in patients with dermatomyositis with anti-Mi2 autoantibodies

OBJECTIVE

To define the clinical phenotype of dermatomyositis (DM) with anti-Mi2 autoantibodies.

METHODS

In this longitudinal cohort study, the prevalence and severity of clinical features at disease onset and during follow-up in patients with anti-Mi2-positive DM were compared to patients with anti-Mi2-negative DM, antisynthetase syndrome (AS), and immune-mediated necrotizing myopathy (IMNM). Longitudinal anti-Mi2 autoantibody titers were assessed.

RESULTS

A total of 58 patients with anti-Mi2-positive DM, 143 patients with anti-Mi2-negative DM, 162 patients with AS, and 170 patients with IMNM were included. Among patients with anti-Mi2-positive DM, muscle weakness was present in 60% at disease onset and occurred in 98% during longitudinal follow-up; fewer patients with anti-Mi2-negative DM developed weakness (85%; p = 0.008). Patients with anti-Mi2-positive DM were weaker and had higher creatine kinase (CK) levels than patients with anti-Mi2-negative DM or patients with AS. Muscle biopsies from patients with anti-Mi2-positive DM had prominent necrosis. Anti-Mi2 autoantibody levels correlated with CK levels and strength (p < 0.001). With treatment, most patients with anti-Mi2-positive DM had improved strength and CK levels; among 10 with multiple serum samples collected over 4 or more years, anti-Mi2 autoantibody titers declined in all and normalized in 3, 2 of whom stopped immunosuppressant treatment and never relapsed. Patients with anti-Mi2-positive DM had less calcinosis (9% vs 28%; p = 0.003), interstitial lung disease (5% vs 16%; p = 0.04), and fever (7% vs 21%; p = 0.02) than did patients with anti-Mi2-negative DM.

CONCLUSIONS

Patients with anti-Mi2-positive DM have more severe muscle disease than patients with anti-Mi2-negative DM or patients with AS. Anti-Mi2 autoantibody levels correlate with disease severity and may normalize in patients who enter remission.

Risk factors and disease mechanisms in myositis

Autoimmune diseases develop as a result of chronic inflammation owing to interactions between genes and the environment. However, the mechanisms by which autoimmune diseases evolve remain poorly understood. Newly discovered risk factors and pathogenic processes in the various idiopathic inflammatory myopathy (IIM) phenotypes (known collectively as myositis) have illuminated innovative approaches for understanding these diseases. The HLA 8.1 ancestral haplotype is a key risk factor for major IIM phenotypes in some populations, and several genetic variants associated with other autoimmune diseases have been identified as IIM risk factors. Environmental risk factors are less well studied than genetic factors but might include viruses, bacteria, ultraviolet radiation, smoking, occupational and perinatal exposures and a growing list of drugs (including biologic agents) and dietary supplements. Disease mechanisms vary by phenotype, with evidence of shared innate and adaptive immune and metabolic pathways in some phenotypes but unique pathways in others. The heterogeneity and rarity of the IIMs make advancements in diagnosis and treatment cumbersome. Novel approaches, better-defined phenotypes, and international, multidisciplinary consensus have contributed to progress, and it is hoped that these methods will eventually enable therapeutic intervention before the onset or major progression of disease. In the future, preemptive strategies for IIM management might be possible.

Autoantibodies in myositis

The discovery of novel autoantigen systems related to idiopathic inflammatory myopathies (collectively referred to as myositis) in adults and children has had major implications for the diagnosis and management of this group of diseases across a wide range of medical specialties. Traditionally, autoantibodies found in patients with myositis are described as being myositis-specific autoantibodies (MSAs) or myositis-associated autoantibodies (MAAs), depending on their prevalence in other, related conditions. However, certain MSAs are more closely associated with extramuscular manifestations, such as skin and lung disease, than with myositis itself. It is very rare for more than one MSA to coexist in the same individual, underpinning the potential to use MSAs to precisely define genetic and disease endotypes. Each MSA is associated with a distinctive pattern of disease or phenotype, which has implications for diagnosis and a more personalized approach to therapy. Knowledge of the function and localization of the autoantigenic targets for MSAs has provided key insights into the potential immunopathogenic mechanisms of myositis. In particular, evidence suggests that the alteration of expression of a myositis-related autoantigen by certain environmental influences or oncogenesis could be a pivotal event linking autoantibody generation to the development of disease.

Guidelines of the Brazilian Society of Rheumatology for the treatment of systemic autoimmune myopathies

BACKGROUND

Recommendations of the Myopathy Committee of the Brazilian Society of Rheumatology for the management and therapy of systemic autoimmune myopathies (SAM).

MAIN BODY

The review of the literature was done in the search for the Medline (PubMed), Embase and Cochrane databases including studies published until June 2018. The Prisma was used for the systematic review and the articles were evaluated according to the levels of Oxford evidence. Ten recommendations were developed addressing the management and therapy of systemic autoimmune myopathies.

CONCLUSIONS

Robust data to guide the therapeutic process are scarce. Although not proven effective in controlled clinical trials, glucocorticoid represents first-line drugs in the treatment of SAM. Intravenous immunoglobulin is considered in induction for refractory cases of SAM or when immunosuppressive drugs are contra-indicated. Consideration should be given to the early introduction of immunosuppressive drugs. There is no specific period determined for the suspension of glucocorticoid and immunosuppressive drugs when individually evaluating patients with SAM. A key component for treatment in an early rehabilitation program is the inclusion of strength-building and aerobic exercises, in addition to a rigorous evaluation of these activities for remission of disease and the education of the patient and his/her caregivers.

Systemic and Tissue Inflammation in Juvenile Dermatomyositis: From Pathogenesis to the Quest for Monitoring Tools

Juvenile Dermatomyositis (JDM) is a systemic immune-mediated disease of childhood, characterized by muscle weakness, and a typical skin rash. Other organ systems and tissues such as the lungs, heart, and intestines can be involved, but may be under-evaluated. The inflammatory process in JDM is characterized by an interferon signature and infiltration of immune cells such as T cells and plasmacytoid dendritic cells into the affected tissues. Vasculopathy due to loss and dysfunction of endothelial cells as a result of the inflammation is thought to underlie the symptoms in most organs and tissues. JDM is a heterogeneous disease, and several disease phenotypes, each with a varying combination of affected tissues and organs, are linked to the presence of myositis autoantibodies. These autoantibodies have therefore been extensively studied as biomarkers for the disease phenotype and its associated prognosis. Next to identifying the JDM phenotype, monitoring of disease activity and disease-inflicted damage not only in muscle and skin, but also in other organs and tissues, is an important part of clinical follow-up, as these are key determinants for the long-term outcomes of patients. Various monitoring tools are currently available, among which clinical assessment, histopathological investigation of muscle and skin biopsies, and laboratory testing of blood for specific biomarkers. These investigations also give novel insights into the underlying immunological processes that drive inflammation in JDM and suggest a strong link between the interferon signature and vasculopathy. New tools are being developed in the quest for minimally invasive, but sensitive and specific diagnostic methods that correlate well with clinical symptoms or reflect local, low-grade inflammation. In this review we will discuss the types of (extra)muscular tissue inflammation in JDM and their relation to vasculopathic changes, critically assess the available diagnostic methods including myositis autoantibodies and newly identified biomarkers, and reflect on the immunopathogenic implications of identified markers.

[Retrospective analysis of anti-TIF1gamma, anti-NXP2 and anti-SAE1/2 antibodies carriers at Bordeaux university hospital from November 2014 to February 2017]

INTRODUCTION

Dermatomyositis are rare autoimmune diseases. The discovery of specific antibodies such as the anti-TIF1γ, anti-SAE1/2 and anti-NXP2 antibodies has been associated with specific clinical phenotypes. The recent development of standardized kits based on immunodot method is a progress in dermatomyositis diagnosis. Here, we report the clinical characteristics of patients carrying these antibodies with or without clinical setting of dermatomyositis.

METHODS

This single-center french retrospective study was conducted from November 2014 to February 2017 at Bordeaux university hospital. Patients carrying anti-TIF1γ, anti-SAE1/2 and anti-NXP2 antibodies, detected by immunodot, were included.

RESULTS

Among the 58 patients included, only 10 were finally diagnosed with dermatomyositis. Some form of cancer was found in all anti-TIF1γ antibodies positive patients associated with dermatomyositis. Among the 48 anti-TIF1γ, anti-SAE1/2 and anti-NXP2 antibodies positive patients without clinical phenotype of dermatomyositis, 30 had autoimmune or inflammatory condition and 39 patients presented a significant biological autoimmunity. None of them developed dermatomyositis during the follow-up.

CONCLUSION

The immunodot kit allowed the diagnosis of 10 dermatomyositis. A high number of autoantibody positive patients without dermatomyositis raises the issue of the immunodot's performances in the context of biological autoimmunity.

Autoimmune Myopathies: Updates on Evaluation and Treatment

The major forms of autoimmune myopathies include dermatomyositis (DM), polymyositis (PM), myositis associated with antisynthetase syndrome (ASS), immune-mediated necrotizing myopathy (IMNM), and inclusion body myositis (IBM). While each of these conditions has unique clinical and histopathological features, they all share an immune-mediated component. These conditions can occur in isolation or can be associated with systemic malignancies or connective tissue disorders (overlap syndromes). As more has been learned about these conditions, it has become clear that traditional classification schemes do not adequately group patients according to shared clinical features and prognosis. Newer classifications are now utilizing myositis-specific autoantibodies which correlate with clinical and histopathological phenotypes and risk of malignancy, and help in offering prognostic information with regard to treatment response. Based on observational data and expert opinion, corticosteroids are considered first-line therapy for DM, PM, ASS, and IMNM, although intravenous immunoglobulin (IVIG) is increasingly being used as initial therapy in IMNM related to statin use. Second-line agents are often required, but further prospective investigation is required regarding the optimal choice and timing of these agents.

Current Treatment for Myositis

PURPOSE OF REVIEW

The purpose of this review was to give an update on treatment modalities for patients with idiopathic inflammatory myopathies, or shortly myositis, excluding the subgroup inclusion body myositis, based on a literature survey on therapies used in myositis. Few controlled trials have been performed in patients with myositis; therefore, we also included a summary of open-label trials, case series, and case reports.

RECENT FINDINGS

Glucocorticoid (GC) in high doses is still the first-line treatment of patients with myositis. There is a general recommendation to combine GCs with another immunosuppressive agent in the early phase of disease to better control disease activity and possibly to reduce the risk for GC-related side effects. Furthermore, combining pharmacological treatment with individualized and supervised exercise can be recommended based on evidence. There is some evidence for the effect of rituximab in patients with certain myositis-specific autoantibodies, whereas other biologic agents are currently being tested in clinical trials.

SUMMARY

Immunosuppressive treatment in combination with exercise is recommended for patients with myositis to reduce disease activity and improve muscle performance. Subgrouping of patients into clinical and serological subtypes may be a way to identify biomarkers for response to specific immunosuppressive and biological agents and should be considered in future trials.

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.

Clinical spectrum of anti-Jo-1-associated disease

PURPOSE OF REVIEW

To provide the most recent evidence on anti-Jo-1 syndrome.

RECENT FINDINGS

Several new evidences on anti-Jo-1 syndrome have recently emerged. It has been clearly established that, at disease onset, the classic clinical triad (arthritis, myositis and interstitial lung disease - ILD) is only rarely observed. Indeed, disease onset with an isolated arthritis is common. Patients presenting with an isolated manifestation are at high risk for the subsequent occurrence of initially lacking triad findings. Moreover, the ex-novo occurrence of accompanying features such as Raynaud's phenomenon, mechanic's hands and fever during follow-up is a strong risk factor for the occurrence of overt antisynthetase syndrome (ASSD) with further triad manifestations. Several contributions on ILD involvement and prognosis have been published, as well as the distinctive muscle MRI characteristics compared with healthy controls, and a novel definition of a rare skin manifestation (hiker's feet).

SUMMARY

Recent evidence has shed a light on the need for a better understanding of the clinical course, imaging modalities and prognosis of anti-Jo-1 syndrome, providing some relevant elements to allow early diagnosis of this often unrecognized disease.

Update on outcome assessment in myositis

The adult and juvenile myositis syndromes, commonly referred to collectively as idiopathic inflammatory myopathies (IIMs), are systemic autoimmune diseases with the hallmarks of muscle weakness and inflammation. Validated, well-standardized measures to assess disease activity, known as core set measures, were developed by international networks of myositis researchers for use in clinical trials. Composite response criteria using weighted changes in the core set measures of disease activity were developed and validated for adult and juvenile patients with dermatomyositis and adult patients with polymyositis, with different thresholds for minimal, moderate and major improvement in adults and juveniles. Additional measures of muscle strength and function are being validated to improve content validity and sensitivity to change. A health-related quality of life measure, which incorporates patient input, is being developed for adult patients with IIM. Disease state criteria, including criteria for inactive disease and remission, are being used as secondary end points in clinical trials. MRI of muscle and immunological biomarkers are promising approaches to discriminate between disease activity and damage and might provide much-needed objective outcome measures. These advances in the assessment of outcomes for myositis treatment, along with collaborations between international networks, should facilitate further development of new therapies for patients with IIM.