Myositis-specific autoantibodies: their clinical and pathogenic significance in disease expression

Peripheral Th17/Treg imbalance in Chinese patients with untreated antisynthetase syndrome associated interstitial lung disease

Interstitial lung disease (ILD) is a common and fatal manifestation of antisynthetase syndrome (ASS). The aim of this study was to provide new insight into investigate peripheral blood lymphocytes, CD4+ T cells, cytokine levels and their relation to the clinical profile of untreated patients with ASS-ILD. The retrospective study population included thirty patients diagnosed with ASS-ILD and 30 healthy controls (HCs). Baseline clinical and laboratory data were collected for all subjects, including peripheral blood lymphocyte, CD4+ T cell subsets measured by flow cytometry, and serum cytokine levels measured by multiple microsphere flow immunofluorescence. Their correlations with clinical and laboratory findings were analyzed by Pearson's or Spearman's correlation analysis. In addition, the Benjamini-Hochberg method was used for multiple correction to adjust the p-values. Patients with ASS-ILD had lower CD8+ T cells, higher proportion of Th17 cells and Th17/Treg ratio than HCs. Serum cytokine levels (IL-1β, IL-6, IL-12, IL-17, IL-8, IL-2, IL-4, IL-10, TNF-α and IFN-γ) were higher in patients with ASS-ILD than HCs. Moreover, Th17/Treg ratio was negatively correlated with diffusing capacity of carbon monoxide (DLCO)%. Our study demonstrated abnormalities of immune disturbances in patients with ASS-ILD, characterized by decreased CD8+ T cells and an increased Th17/Treg ratio, due to an increase in the Th17 cells. These abnormalities may be the immunological mechanism underlying the development of ILD in ASS.

Prevalence and Clinical Implications of Autoantibodies in Juvenile Dermatomyositis: A Single-Center Experience From India

OBJECTIVE

​​This study aimed to characterize the profile of myositis-specific and myositis-associated autoantibodies (MSAs/MAAs) in an Indian cohort of juvenile dermatomyositis (JDM) patients and correlate them with clinical features and outcomes.

METHODS

Forty-three children diagnosed with JDM were enrolled for this observational study. Clinical details (presentation, course, and outcome) were noted in a predesigned proforma. Serum samples were tested for 16 MSAs/MAAs by line immunoassay. MSAs/MAAs were correlated with clinical features and outcome (defined as a complete clinical response [≥6 months' disease inactivity on medication] or complete remission [≥6 months' inactivity off all drugs]).

RESULTS

Thirty-five subjects (81.4%) had at least 1 MSA/MAA detected. The most common antibodies were anti-NXP2 (n = 13, 30.2%), anti-TIF1γ (n = 10, 23.2%), and anti-MDA-5 (n = 8, 18.6%). No patient had anti-Ku, anti-Pm Scl-100, anti-PL-12, anti-EJ, anti-OJ, or anti-Ro52. Thirty-two patients (74.4%) attained a complete clinical response over a median follow-up duration of 14 months, among which 6 (13.9%) achieved complete remission over a median follow-up duration of 30 months. Anti-TIF1γ was associated with younger age at onset (≤3 years) (odds ratio [OR], 6.25; 95% confidence interval [CI], 1.15-34.12; p = 0.034) and disease flares after attaining complete response (OR, 10.18; 95% CI, 1.64-70.93; p = 0.013). Patients with anti-NXP2 had higher odds of severe muscular weakness (OR, 3.73; 95% CI, 0.95-14.59; p = 0.058) and truncal weakness (OR, 3.89; 95% CI, 0.97-15.64; p = 0.056). One child with anti-MDA-5 positivity had interstitial lung disease. We found no association between the MSA/MAA profile and the achievement of complete clinical response or remission.

CONCLUSIONS

MSAs/MAAs were identified in 81% of children with JDM in our study, which is higher than most other studies. The most frequently observed antibodies displayed a pattern consistent with other studies. Anti-TIF1γ was associated with a younger age at onset and disease flares even after attaining a complete clinical response. Anti-NXP2 had higher odds of severe muscular weakness. These observations suggest consistency in certain phenotypic associations observed across geographic boundaries.

Mitochondrial defects in sporadic inclusion body myositis-causes and consequences

Sporadic inclusion body myositis (sIBM) is a distinct subcategory of Idiopathic Inflammatory Myopathies (IIM), characterized by unique pathological features such as muscle inflammation, rimmed vacuoles, and protein aggregation within the myofibers. Although hyperactivation of the immune system is widely believed as the primary cause of IIM, it is debated whether non-immune tissue dysfunction might contribute to the disease's onset as patients with sIBM are refractory to conventional immunosuppressant treatment. Moreover, the findings that mitochondrial dysfunction can elicit non-apoptotic programmed cell death and the subsequent immune response further support this hypothesis. Notably, abnormal mitochondrial structure and activities are more prominent in the muscle of sIBM than in other types of IIM, suggesting the presence of defective mitochondria might represent an overlooked contributor to the disease onset. The large-scale mitochondrial DNA deletion, aberrant protein aggregation, and slowed organelle turnover have provided mechanistic insights into the genesis of impaired mitochondria in sIBM. This article reviews the disease hallmarks of sIBM, the plausible contributors of mitochondrial damage in the sIBM muscle, and the immunological responses associated with mitochondrial perturbations. Additionally, the potential application of mitochondrial-targeted chemicals as a new treatment strategy to sIBM is explored and discussed.

Defining criteria for disease activity states in juvenile dermatomyositis based on the Juvenile Dermatomyositis Activity Index

OBJECTIVES

To develop and validate the cut-offs in the Juvenile DermatoMyositis Activity Index (JDMAI) to distinguish the states of inactive disease (ID), low disease activity (LDA), moderate disease activity (MDA) and high disease activity (HDA) in children with juvenile dermatomyositis (JDM).

METHODS

For cut-off definition, data from 139 patients included in a randomised clinical trial were used. Among the six versions of the JDMAI, JDMA1 (score range 0-40) and JDMAI2 (score range 0-39) were selected. Optimal cut-offs were determined against external criteria by calculating different percentiles of score distribution and through receiver operating characteristic curve analysis. External criteria included the modified Pediatric Rheumatology International Trials Organization (PRINTO) criteria for clinically ID in JDM (for ID) and PRINTO levels of improvement in the clinical trial (for LDA and HDA). MDA cut-offs were set at the score interval between LDA and HDA cut-offs. Cut-off validation was conducted by assessing construct and discriminative ability in two cohorts including a total of 488 JDM patients.

RESULTS

The calculated JDMAI1 cut-offs were ≤2.4 for ID, ≤6.6 for LDA, 6.7-11 for MDA and >11 for HDA. The calculated JDMAI2 cut-offs were ≤5.2 for ID, ≤8.5 for LDA, 8.6-11.3 for MDA and >11.3 for HDA. The cut-offs discriminated strongly among disease activity states defined subjectively by caring physicians and parents, parents' satisfaction or non-satisfaction with illness outcome, levels of pain, fatigue, physical functional impairment and physical well-being.

CONCLUSIONS

Both JDMAI1 and JDMAI2 cut-offs revealed good metrologic properties in validation analyses and are, therefore, suited for application in clinical practice and research.

Comparison of characteristics and anti-MDA5 antibody distribution and effect between clinically amyopathic dermatomyositis and classic dermatomyositis: a retrospective case-control study

Background

Clinically amyopathic dermatomyositis (CADM) is a distinct subtype of dermatomyositis (DM) characterized by typical DM cutaneous findings but with minimal or no evidence of myositis. It possesses unique features different from classic DM (CDM). Anti-melanoma differentiation-associated gene 5 (MDA5) antibodies were found in CADM and are thought to increase the risk of rapidly progressive interstitial lung disease (RP-ILD) and are present in both CADM and CDM patients, affecting their condition and prognosis. Nevertheless, no large-sample studies have compared all aspects concerning patients with CADM and those with CDM. This study aimed to investigate differences in clinical characteristics and risk factors for mortality between CADM and CDM and to clarify the distribution and impact of anti-MDA5 antibodies in patients with these conditions.

Methods

A retrospective case-control study included 330 patients and collected and analyzed their clinical data from The First Affiliated Hospital of Shandong First Medical University and Shandong Provincial Hospital of Traditional Chinese Medicine between January 2015 and July 2022; all patients were followed up to evaluate changes in their condition and prognosis. Several new cohorts were designed around anti-MDA5 antibodies to explore their distribution and impact in CADM and CDM.

Results

We found CADM to be associated with higher rates of mortality, 1-year mortality, interstitial lung disease (ILD), and RP-ILD than CDM. In CADM, RP-ILD, anti-MDA5 antibodies, and high ferritin and lactate dehydrogenase (LDH) levels were identified as independent risk factors for death. In CDM, the neutrophil-to-lymphocyte ratio, anti-MDA5 antibodies, and high ferritin levels were shown to be independent risk factors for death, whereas mechanic's hand was considered a protective factor against it. Anti-MDA5 antibody-positive patients did not exhibit any significant difference based on whether they belonged to the CADM or CDM groups. When no anti-MDA5 antibody-positive patients participated, the ferritin levels and rates of RP-ILD and ILD were still higher in CADM than in CDM; however, such differences decreased, whereas the LDH levels, rates of mortality, and 1-year mortality did not differ. Anti-MDA5 antibody-positive patients consistently showed higher LDH and ferritin levels, lower lymphocyte levels, higher probability of RP-ILD and ILD, and worse prognosis than anti-MDA5 antibody-negative patients, irrespective of whether the patients had DM, CADM, or CDM.

Conclusion

Patients with CADM exhibit relatively worse symptoms, serological findings, and prognosis than those with CDM. Furthermore, patients with CADM and those with CDM have commonalities and differences in risk factors for death. Moreover, CADM may necessitate earlier and more aggressive treatment strategies than CDM. Anti-MDA5 antibodies occur at a high level in patients with CADM, not only affecting the symptoms and prognosis of DM but also having a non-negligible impact on the differences between CADM and CDM. Hence, screening for anti-MDA5 antibodies in patients with CADM and CDM is extremely essential.

Sarcoplasmic Myxovirus Resistance Protein A: A Study of Expression in Idiopathic Inflammatory Myopathy

Background

Idiopathic inflammatory myopathies (IIM) are a heterogeneous group of autoimmune diseases affecting primarily proximal muscles. Major subtypes include dermatomyositis, polymyositis, inclusion body myositis, immune-mediated necrotizing myopathy and antisynthetase syndrome. Overexpression of sarcoplasmic myxovirus-resistance protein A (MxA) has been observed in muscle biopsy specimens of dermatomyositis but is rarely seen in other subtypes of IIM and other myopathies.

Objective

We evaluate the expression of sarcoplasmic MxA and its diagnostic value in IIM and other myopathies.

Methods

One hundred and thirty-eight muscle biopsy specimens with the diagnosis of IIM and other myopathies from 2011 to 2020 were reviewed and stained for MxA by immunohistochemistry. The difference of the expression of MxA between IIM and other myopathies was analyzed by Fisher's exact test, and the sensitivity and specificity of MxA immunohistochemistry in the diagnosis of IIM were assessed.

Results

MxA protein was positive in 16/138 (11.6%) specimens. All 12 dermatomyositis specimens positive for MxA protein were positive in perifascicular area pattern. Only dermatomyositis specimens had a significantly higher percentage of positive sarcoplasmic MxA expression than specimens of other subtypes of IIM (p<0.001). Sarcoplasmic MxA expression for dermatomyositis diagnosis had a sensitivity of 46.15% (95% CI 26.59-66.63%) and a specificity of 94.44% (95% CI 81.34-99.32%) with the positive and negative likelihood ratio of 8.31 (95% CI 2.03-34.01) and 0.57 (95% CI 0.40-0.82), respectively.

Conclusion

The MxA immunohistochemistry is highly specific for dermatomyositis and should be added to a routine inflammatory panel of muscle biopsy. MxA expression should be cautiously interpreted to avoid pitfalls.

Differences in sex- and age-associated mortality in patients with anti-MDA5-positive dermatomyositis

OBJECTIVES

The effect of sex and age on the outcomes of patients with anti-melanoma differentiation-associated gene 5 (MDA5)-positive dermatomyositis (MDA5+ DM) remains unclear. This study aimed to investigate the impact of sex and age on the prognosis of patients with MDA5+ DM.

METHODS

We included 251 patients (women, 156; men, 95), who were newly diagnosed with MDA5+ DM between 2014 and 2021. The outcome was 6-month all-cause mortality after the diagnosis of interstitial lung disease. Cox regression analysis was used to assess the mortality. Adjusted restricted cubic spline analysis was performed to explore the non-linear relationship between age and outcomes.

RESULTS

The 6-month mortality rates of women and men were 36.5% and 46.3%, respectively. Multivariate Cox regression revealed that ≥60 years of age was significantly associated with the risk of death (hazard ratio, 2.43; 95% confidence interval, 1.02-5.78). The trend of the risk of 6-month mortality in men was relatively flat until 54 years and increased rapidly afterwards (hazard ratio, 1.14; 95% confidence interval, 1.01-1.29). In contrast, the 6-month mortality rate showed a low linear increasing trend with age among females.

CONCLUSIONS

Patients with MDA5+ DM, who received contemporary treatment, had unfavourable outcomes. The 6-month mortality risk increased with age, particularly in male patients aged >54 years.

Diagnosis and Management of Myositis-Associated Lung Disease

Although interstitial lung disease (ILD) is a leading cause of morbidity and mortality in patients with inflammatory myopathies, the current definition and diagnostic criteria of autoimmune myositis remain inadequate to capture the large proportion of patients with lung-dominant disease. As a result, these patients present unique diagnostic and treatment challenges for even the most experienced clinicians. This article highlights the emerging role of autoantibodies in the diagnosis, classification, and management of patients with ILD. We propose alternative nomenclature to facilitate research on this unique patient population. Additionally, evidence supporting the various therapies used in the treatment of myositis-associated ILD is reviewed. The classification and treatment of patients with myositis-associated ILD remains challenging. A standardized therapeutic approach to these patients is lacking, and prospective studies in the field are needed to determine optimal treatment regimens.

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.

Profile of specific and associated autoantibodies in patients with idiopathic inflammatory myopathies in a Colombian population

Objectives

Idiopathic inflammatory myopathies (IIMs) are chronic, autoimmune diseases with several forms of presentation. Diagnosis is mostly clinical in our region. Our aim was to evaluate the autoantibody profile of patients with IIMs.

Methods

This study is a cross-sectional study with a prospective recollection of data, conducted between 2019–2021, in a single center in Cali, Colombia. Patients with a clinical diagnosis or suspicion of IIM were included. The presence of myositis-specific/associated antibodies was evaluated by immunoblotting in serum samples. Phenotypic characterization was performed.

Results

A total of 36 patients were included. The mean age was 50.6 (16.7) years, and 20 (55.6%) were female. Eighteen (50%) patients were seropositive, of which 11 (30.5%) presented one positive antibody, with anti-TIF1ɣbeing the most frequent (n = 4, 11.1%), followed by anti-Ro52 (n = 2, 5.6%). Seven patients (19.4%) showed >1 positive antibody. Dermatomyositis was the most frequent type of IIM in seropositive patients (n = 8, 44.4%), followed by anti-synthetase syndrome (n = 4, 22.2%). Weakness was symmetric and presented in the upper and lower extremities in 11 (61.1%) patients each. Both respiratory insufficiency and weight loss were seen in 7 (38.9%) patients, Gottron papules in six (33.3%) patients, and heliotrope rash, esophageal dysmotility, and myalgia in 5 (27.8%) patients. Pulmonary interstitial disease was seen in 4 (22.2%, with antibodies for anti-Ro52, anti-MDA5 + anti-Jo1 + anti-TIF1ɣ, anti-MDA5 + anti-SAE1 + anti-NXP2, and anti-cN1A + anti-Ro52) patients, and malignancy was seen in 2 (11.1%) patients (1 with anti-Mi2β and 1 with anti-TIF1ɣ + anti-Mi2α). In all, 7 (19.4%) patients required intensive care (2 seropositive, 1 with anti-PL7, 1 with anti-MDA5 + anti-Jo1 + anti-TIF1ɣ), and 1 (2.8%) (seronegative) patient died.

Conclusion

This study is the first study in the Southwest of Colombia that evaluates myositis-specific/associated antibodies in IIM. Half of the patients were seropositive. Anti-TIF1ɣwas the most frequent MSA and anti-Ro52 was the most frequent MAA. Several patients presented antibody combinations. Further studies are needed to fully associate phenotypes with antibodies.

Muscle B mode ultrasound and shear-wave elastography in idiopathic inflammatory myopathies (SWIM): criterion validation against MRI and muscle biopsy findings in an incident patient cohort

Background

B mode ultrasound (US) and shear wave elastography (SWE) are easily accessible imaging tools for idiopathic inflammatory myopathies (IIM) but require further validation against standard diagnostic procedures such as MRI and muscle biopsy.

Methods

In this prospective cross-sectional study we compared US findings to MRI and muscle biopsy findings in a group of 18 patients (11 F, 7 M) with active IIM (dermatomyositis 6, necrotising autoimmune myopathy 7, inclusion body myositis 4, overlap myositis 1) who had one or both procedures on the same muscle. US domains (echogenicity, fascial thickness, muscle bulk, shear wave speed and power doppler) in the deltoid and vastus lateralis were compared to MRI domains (muscle oedema, fatty infiltration/atrophy) and muscle biopsy findings (lymphocytic inflammation, myonecrosis, atrophy and fibro-fatty infiltration). A composite index score (1–4) was also used as an arbitrary indicator of overall muscle pathology in biopsies.

Results

Increased echogenicity correlated with the presence of fatty infiltration/atrophy on MRI (p = 0.047) in the vastus lateralis, and showed a non-significant association with muscle inflammation, myonecrosis, fibrosis and fatty infiltration/atrophy (p > 0.333) Severe echogenicity also had a non-significant association with higher composite biopsy index score in the vastus lateralis (p = 0.380). SWS and US measures of fascial thickness and muscle bulk showed poor discrimination in differentiating between pathologies on MRI or muscle biopsy. Power Doppler measures of vascularity correlated poorly with the presence of oedema on MRI, or with inflammation or fatty infiltration on biopsy. Overall, US was sensitive in detecting the presence of muscle pathology shown on MRI (67–100%) but showed poorer specificity (13–100%). Increased echogenicity showed good sensitivity when detecting muscle pathology (100%) but lacked specificity in differentiating muscle pathologies (0%). Most study participants rated US as the preferred imaging modality.

Conclusions

Our findings show that US, in particular muscle echogenicity, has a high sensitivity, but low specificity, for detecting muscle pathology in IIM. Traditional visual grading scores are not IIM-specific and require further modification and validation. Future studies should continue to focus on developing a feasible scoring system, which is reliable and allows translation to clinical practice.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41927-022-00276-w.

Management of interstitial lung disease (ILD) in myositis syndromes: A practical guide for clinicians

Inflammatory myopathies are heterogeneous clinico-serological syndromes, with variable clinical manifestations. Interstitial lung disease (ILD) is a major cause of morbidity and mortality in patients with myositis. The clinical manifestation of myositis-ILD is heterogeneous, e.g., with acute-on-chronic presentations, as well as the chronic aftermath of acute disease. Here, we have largely divided myositis-ILD into three main prognostic groups which require different treatment approaches: mild-moderate (subacute), severe or progressive (acute or subacute) and rapidly progressive, life-threatening. In current clinical practice, the treatment of myositis-ILD involves immunomodulation in an induction-maintenance treatment paradigm. There is now an option to add antifibrotics to slow the progression of established fibrosis in selected cases with chronic progressive phenotype. Here, we describe current concepts in myositis-ILD and aim to provide a practical guide for clinicians on how to approach assessment, including early identification of ILD, phenotyping of patients according to clinical trajectory and likely prognosis and stratified management adopting multi-disciplinary cross-speciality expertise, with close collaboration between rheumatology and respiratory physicians.

Innate Immunity in Calcinosis Cutis

Calcinosis cutis is the deposition of calcium salts in the skin and subcutaneous tissue, manifesting as variably shaped papules, nodules, and plaques that can substantially impair quality of life. The pathophysiology of calcinosis cutis involves dysregulation of proinflammatory cytokines, leukocytes, and other components of the innate immune system. In some conditions associated with calcinosis cutis, elevated serum calcium, phosphate, and vitamin D may also perturb innate immunity. The mechanisms by which these lead to cutaneous and subcutaneous calcification likely parallel those seen in vascular calcification. The role of aberrant innate immunity is further supported by the association between various autoantibodies with calcinosis cutis, such as anti-MDA5, anti-NXP2, anti-centromere, and anti-topoisomerase I. Treatments for calcinosis cutis remain limited and largely experimental, although mechanistically many therapies appear to focus on dampening innate immune responses. Further research is needed to better understand the innate immune pathophysiology and establish treatment options based on randomized-controlled trials.

Complete response to pembrolizumab in a patient with dermatomyositis and MMR deficient ovarian cancer: A case report

•Immune checkpoint inhibitors can be safely administered to patients with dermatomyositis.•Immunosuppressants did not impact the efficacy of treatment with an immune check point inhibitor.•Patients with autoimmune disorders who require immune check point inhibitors should be monitored by a rheumatologist.

Myositis-specific Antibodies: Overview and Clinical Utilization

Purpose of review-To review autoantibodies associated with different subtypes of idiopathic inflammatory myopathy (IIM) and their clinical applications. IIM are a heterogenous group of autoimmune disorders characterized by muscle weakness, cutaneous features, and internal organ involvement. The diagnosis and classification, which is often challenging, is made using a combination of clinical features, muscle enzyme levels, imaging, and biopsy. The landmark discoveries of novel autoantibodies specific to IIM subtypes have been one of the greatest advancements in the field of myositis. The specificity of these autoantibodies has simplified the diagnostic algorithm of IIM with their heterogenous presentation and outdated the earlier diagnostic criteria. Myositis-specific antibodies (MSAs) have improved diagnostics, clinical phenotyping, and prognostic stratification of the subtypes of IIMs. Furthermore, the levels of certain MSAs correlate with disease activity and muscle enzyme levels such that titers may be able to be used to predict disease course and treatment response.

Clinical features and immune-related protein patterns of anti-MDA5 positive clinically amyopathic dermatomyositis Dutch patients

OBJECTIVES

The presence of melanoma differentiation-associated protein 5 (MDA5) antibodies in patients with dermatomyositis (DM) is associated with the development of a rapidly progressive interstitial lung disease (RPILD), unresponsive to conventional treatment. We characterize patients and provide more insight into potential biomarkers to identify patients with RPILD.

METHODS

Patients diagnosed with anti-MDA5 positive DM between December 2015 and November 2017 were included in this study. Clinical data were retrospectively retrieved from medical records. 180 immune-related markers were measured in sera of 16 patients and 15 healthy controls using proximity extension assay based technology.

RESULTS

Twenty patients were included, with a median time from symptoms till diagnosis of 4 months. All patients had clinically amyopathic DM. Interstitial lung disease (ILD) was present at diagnosis in 94% of the patients, 45% presented with RPILD. The mortality rate was 35% within 4 months after diagnosis and respiratory failure was the main cause of death in these patients. Furthermore, unsupervised analysis revealed that patients with RPILD show clearly different inflammatory serum profiles than healthy controls. In addition, in comparison to healthy controls, the interferon, Interleukin (IL)1, IL10 and IL18 signalling pathways are different regulated in anti-MDA5 positive patients.

CONCLUSION

In this Dutch anti-MDA5 positive CADM cohort, one third of the patients died due to RPILD soon after diagnosis, which underlines the severity of this disease. In addition, we have found several possible pathways that are differentially regulated in RPILD vs no RPILD DM and healthy controls. These markers await further validation before clinical use.

Clinically amyopathic dermatomyositis with interstitial lung disease double-positive for anti-MDA5 and anti-PL12 antibodies

Anti-melanoma differentiation-associated gene 5 (MDA5) and anti-aminoacyl-tRNA synthetase (ARS) antibodies are two major myositis-specific autoantibodies with distinct clinical features. However, the clinical course remains unclear in patients with clinically amyopathic dermatomyositis (CADM)-interstitial lung disease (ILD) who have co-existing anti-MDA5 and anti-ARS antibodies. Here, we describe the case of a 32-year-old woman with CADM-ILD who had anti-MDA5 and anti-PL12 antibodies. Her serum ferritin level was within the normal range. However, chest computed tomography revealed bilateral lower-lobe consolidation and ground-glass opacities. Treatment with prednisolone and immunosuppressants was successful in improving the skin lesion and ILD, but relapse occurred on reducing the dose of prednisolone. These clinical features match those of anti-ARS antibody-positive dermatomyositis-ILD. Because these two conditions show significantly different clinical features and require different intensities of treatment, clinicians should carefully follow-up these patients throughout the course of the disease.

Morphological Characteristics of Idiopathic Inflammatory Myopathies in Juvenile Patients

Background: In juvenile idiopathic inflammatory myopathies (IIMs), morphological characteristic features of distinct subgroups are not well defined. New treatment strategies require a precise diagnosis of the subgroups in IIM, and, therefore, knowledge about the pathomorphology of juvenile IIMs is warranted. Methods: Muscle biopsies from 15 patients (median age 8 (range 3–17) years, 73% female) with IIM and seven controls were analyzed by standard methods, immunohistochemistry, and transmission electron microscopy (TEM). Detailed clinical and laboratory data were accessed retrospectively. Results: Proximal muscle weakness and skin symptoms were the main clinical symptoms. Dermatomyositis (DM) was diagnosed in 9/15, antisynthetase syndrome (ASyS) in 4/15, and overlap myositis (OM) in 2/15. Analysis of skeletal muscle tissues showed inflammatory cells and diffuse upregulation of MHC class I in all subtypes. Morphological key findings were COX-deficient fibers as a striking pathology in DM and perimysial alkaline phosphatase positivity in anti-Jo-1-ASyS. Vascular staining of the type 1 IFN-surrogate marker, MxA, correlated with endothelial tubuloreticular inclusions in both groups. None of these specific morphological findings were present in anti-PL7-ASyS or OM patients. Conclusions: Morphological characteristics discriminate IIM subtypes in juvenile patients, emphasizing differences in aetiopathogenesis and supporting the notion of individual and targeted therapeutic strategies.

How to report the antinuclear antibodies (anti-cell antibodies) test on HEp-2 cells: guidelines from the ICAP initiative

Results of the anti-nuclear antibodies-indirect immunofluorescence assay (anti-cell antibodies test) on HEp-2 cell substrates should be communicated to clinicians in a standardized way, adding value to laboratory findings and helping with critical clinical decisions. This paper proposes a test report based on the practices informed by 118 laboratories in 68 countries, with recommendations from the International Consensus on ANA Patterns (ICAP) group. Major focus is placed on the report format containing endpoint titers, immunofluorescence patterns together with anti-cell (AC) nomenclature, remarks on follow-up or reflex testing, and possible other autoantibody associations. ISO 15,189 directives were integrated into the test report. Special situations addressed include serum screening dilutions and endpoint titers, relevance of immunofluorescence patterns with special attention to cytoplasmic patterns, mixed and compound patterns, and how to report different titers corresponding to multiple patterns or autoantibodies in the same sample. This paper suggests a subtitle for the HEp-2-IIFA, namely anti-cell antibodies test, which could gradually substitute the original outdated ANA nomenclature. This ICAP pro forma report represents a further step in harmonizing the way relevant clinical information could be provided by laboratories.

Profiling Serum Antibodies Against Muscle Antigens in Facioscapulohumeral Muscular Dystrophy Finds No Disease-Specific Autoantibodies

BACKGROUND

FSHD is caused by specific genetic mutations resulting in activation of the Double Homeobox 4 gene (DUX4). DUX4 targets hundreds of downstream genes eventually leading to muscle atrophy, oxidative stress, abnormal myogenesis, and muscle inflammation. We hypothesized that DUX4-induced aberrant expression of genes triggers a sustained autoimmune response against skeletal muscle cells.

OBJECTIVE

This study aimed at the identification of autoantibodies directed against muscle antigens in FSHD. Moreover, a possible relationship between serum antibody reactivity and DUX4 expression was also investigated.

METHODS

FSHD sera (N = 138, 48±16 years, 48% male) and healthy control sera (N = 20, 47±14 years, 50% male) were analyzed by immunoblotting for antibodies against several skeletal muscle protein extracts: healthy muscle, FSHD muscle, healthy and FSHD myotubes, and inducible DUX4 expressing myoblasts. In addition, DUX4 expressing myoblasts were analyzed by immunofluorescence with FSHD and healthy control sera.

RESULTS

The results showed that the reactivity of FSHD sera did not significantly differ from that of healthy controls, with all the tested muscle antigen extracts. Besides, the immunofluorescent staining of DUX4-expressing myoblasts was not different when incubated with either FSHD or healthy control sera.

CONCLUSION

Since the methodology used did not lead to the identification of disease-specific autoantibodies in the FSHD cohort, we suggest that autoantibody-mediated pathology may not be an important disease mechanism in FSHD. Nevertheless, it is crucial to further unravel if and which role the immune system plays in FSHD pathogenesis. Other innate as well as adaptive immune players could be involved in the complex DUX4 cascade of events and could become appealing druggable targets.

Prognosis of adult idiopathic inflammatory myopathy-associated interstitial lung disease: a retrospective study of 679 adult cases

OBJECTIVES

Few studies have investigated the prognostic factors for idiopathic inflammatory myopathy-associated interstitial lung disease (IIM-ILD) across different clinical/serological phenotypes.

METHODS

We conducted a retrospective analysis of patients diagnosed with IIM between January 2012 and December 2017.

RESULTS

Of the 760 IIM cases registered, 679 adult cases were included in this study. ILD was present in 508 cases, and the presence of ILD in the clinically amyopathic DM, DM and PM groups was 92.7, 73.6 and 55.1%, respectively (P < 0.01). The prevalence of ILD in the anti-synthetase antibody (ASA)+-IIM group was higher than that in ASA--IIM group (95.2 vs 72.4%, P < 0.01); no such difference was found between the anti-histidyl-tRNA synthetase (Jo-1)+-IIM and Jo-1-ASA+-IIM groups (93.0 vs 98.5%, P > 0.05). The prevalence of ILD in the melanoma differentiation-associated protein-5 (MDA-5)+-IIM group was higher than that in MDA-5--IIM group (97.8 vs 72.1%, P < 0.01). Among adults with IIM, men with concurrent ILD, who were older than 50 years, were most likely to die. No significant difference was found in the all-cause mortality rates between DM-ILD and clinically amyopathic DM-ILD groups (33.3 vs 23%, P > 0.05), although both were higher than that in PM group (13.2%, P = 0.01 and P < 0.05, respectively). No difference was found in the all-cause mortality rates between MDA5-ASA--IM-ILD and MDA5-ASA+-IM-ILD groups (17.2 vs 12.8%, P > 0.05), and both were lower than that in MDA5+ASA--IM-ILD group (33.7%, P < 0.05).

CONCLUSION

The prevalence of ILD in IIM and the prognosis of IIM-ILD patients may vary depending on the statuses of the ASA and MDA-5 antibodies.

Texture analysis of muscle MRI: machine learning-based classifications in idiopathic inflammatory myopathies

To develop a machine learning (ML) model that predicts disease groups or autoantibodies in patients with idiopathic inflammatory myopathies (IIMs) using muscle MRI radiomics features. Twenty-two patients with dermatomyositis (DM), 14 with amyopathic dermatomyositis (ADM), 19 with polymyositis (PM) and 19 with non-IIM were enrolled. Using 2D manual segmentation, 93 original features as well as 93 local binary pattern (LBP) features were extracted from MRI (short-tau inversion recovery [STIR] imaging) of proximal limb muscles. To construct and compare ML models that predict disease groups using each set of features, dimensional reductions were performed using a reproducibility analysis by inter-reader and intra-reader correlation coefficients, collinearity analysis, and the sequential feature selection (SFS) algorithm. Models were created using the linear discriminant analysis (LDA), quadratic discriminant analysis (QDA), support vector machine (SVM), k-nearest neighbors (k-NN), random forest (RF) and multi-layer perceptron (MLP) classifiers, and validated using tenfold cross-validation repeated 100 times. We also investigated whether it was possible to construct models predicting autoantibody status. Our ML-based MRI radiomics models showed the potential to distinguish between PM, DM, and ADM. Models using LBP features provided better results, with macro-average AUC values of 0.767 and 0.714, accuracy of 61.2 and 61.4%, and macro-average recall of 61.9 and 59.8%, in the LDA and k-NN classifiers, respectively. In contrast, the accuracies of radiomics models distinguishing between non-IIM and IIM disease groups were low. A subgroup analysis showed that classification models for anti-Jo-1 and anti-ARS antibodies provided AUC values of 0.646–0.853 and 0.692–0.792, with accuracy of 71.5–81.0 and 65.8–78.3%, respectively. ML-based TA of muscle MRI may be used to predict disease groups or the autoantibody status in patients with IIM and is useful in non-invasive assessments of disease mechanisms.

Rituximab in the treatment of immune-mediated necrotizing myopathy: a review of case reports and case series

Immune-mediated necrotizing myopathy (IMNM) is a group of immune-related myopathies characterized by progressive proximal muscle weakness, extremely high serum creatine kinase (CK) levels, and necrotic muscle fibers with a relative lack of inflammation. Treatment of IMNM is challenging, with most cases refractory to high-dose steroids in combination with multiple immunotherapies. The role of rituximab (RTX) for IMNM has been explored in isolated case reports and small series. The aim of this article was to perform a literature review of patients with IMNM treated with RTX and to evaluate RTX efficacy and safety. A total of 34 patients with IMNM were reviewed: 52.9% (18/34) with anti-signal recognition particle (SRP) antibodies and 47.1% (16/34) with anti-3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) antibodies. Patient age at onset varied from 11 years to 81 years (mean 41 years). The majority of patients presented as a severe proximal muscle weakness and the peak level of CK varied from 3900 IU/L to 56,000 IU/L (mean 18,440 IU/L). Prior to RTX administration, all patients were treated with high-dose steroids and most were treated with multiple immunotherapies. The reason for initiating RTX was that 64.7% (22/34) of patients showed no improvement after previous treatments, and 35.3% (12/34) of patients relapsed when attempting to wean steroids or other immunosuppressive agents. With regard to RTX efficacy, 61.8% (21/34) of patients presented a response to RTX. Our data may support the use of RTX as an effective treatment strategy against IMNM resistant to steroids and multiple immunotherapies. Meanwhile, RTX as a first-line therapy could be a choice in IMNM, particularly in African Americans with anti-SRP antibody-positive subsets. ANA, antinuclear antibody; CK, creatine kinase; HMGCR, 3-hydroxy-3-methylglutaryl-CoA reductase; IMNM, immune-mediated necrotizing myopathy; MAC, membrane attack complex; MHC-I, major histocompatibility complex-I; RTX, rituximab; SRP, signal recognition particle.

Lambert-Eaton Myasthenic Syndrome and Dermatomyositis With Anti-TIF1-gamma Autoantibody: A Unique Association of Autoimmune Neuromuscular Conditions Without Malignancy

ABSTRACT

Lambert-Eaton myasthenic syndrome (LEMS) is a presynaptic neuromuscular junction disorder, and dermatomyositis (DM) is an idiopathic inflammatory myopathy. LEMS and DM are uncommon conditions that can present similarly and are often associated with autoantibodies. Concomitant LEMS and DM have only been reported a few times, and most of those cases were paraneoplastic. We present the first reported case of a patient with antivoltage gated calcium channel antibody positive LEMS who subsequently developed DM with antitranscription intermediary factor 1-gamma (anti-TIF1-γ) antibodies. Interestingly, both conditions occurred without evidence of malignancy. This diagnosis of LEMS and DM with characteristic clinical, electrodiagnostic, and histopathological evidence led to a beneficial modification of the patient's therapeutic regimen. Due to the fact that overlapping concurrent neuromuscular conditions are rare, a high clinical suspicion is needed to identify, evaluate (including appropriate cancer screenings), and appropriately treat these patients.

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.

Clinical features, muscle biopsy scores, myositis specific antibody profiles and outcome in juvenile dermatomyositis

INTRODUCTION

Juvenile dermatomyositis (JDM) is the most common inflammatory myopathy of childhood.

OBJECTIVE

To analyze clinical features, paraclinical examinations, MSAs, treatment response and long-term outcome in a JDM cohort METHODS: 58 patients (35F, 23 M) from a tertiary referral center in the last two decades are included.

RESULTS

Mean age at onset was 8.1 ± 4.3, with a mean follow-up period of 5.66±3.59 years. Dermatological manifestations (91%) and muscle weakness (76%) were the key diagnostic elements. Elevated serum creatine kinase levels (86%), electromyography (23/25), muscle MRI (12/15), and muscle biopsy (n = 35) were compatible with the diagnosis. Out of 46 patients tested, 34 (76%) had autoantibodies, with NXP2 (21.7%), followed by TIF1g (17.4%), MDA5 (8.7%), and Mi-2 (8.7%). Presence of TIF1g and NXP2 indicated a severe course; and Ku a much severe course compared to previous studies. Corticosteroids (100%) combined with methotrexate (93%) was the initial treatment. Biological disease modifying anti-rheumatic drugs (DMARDs) were used in 22% of the cohort. Calcinosis (36%) was the most common long-term complication, associated with disease onset ≤6 years, higher muscle biopsy scores and MDA5 positivity. Complete remission was achieved in 65.5% of the patients in a median 24 (IQR 11.8-42.5) months with a relapse rate of 26.3%. 43.9% of NXP2 and 33.3% of TIF-1 g positive patients had a relapse. Course was monophasic (31%), polyphasic (17.2%), chronic (51.8%) without mortality.

CONCLUSION

Integration of clinical features with laboratory and biopsy findings may help to predict prognosis and guide treatment in JDM. In our cohort calcinosis was associated with age, MDA5 autoantibodies, and muscle biopsy scores.

A 65-year-old Woman With Persistent Dyspnea, Arthritis, and Raynaud's Phenomenon

Antisynthetase syndrome (AS) is a rare disease that affects patients with inflammatory myopathies such as polymyositis (PM) and dermatomyositis (DM). In patients with AS, up to 95% of patients develop antisynthetase syndrome-associated interstitial lung disease (AS-ILD). Although AS-ILD commonly occurs in patients with a well-established diagnosis of AS, it can be the first or only manifestation of an occult AS. The frequency of interstitial lung disease (ILD), myopathy, and skin involvement are often dependent on the type of myositis-specific antibodies present. AS-ILD patients who are positive for both anti-Jo-1 and anti-SSA/RO-52 autoantibodies often present with a severe degree of lung restriction on pulmonary function tests and radiologic imaging with an inadequate response toward immunosuppressive therapies. We describe a 65-year-old woman who presents with chronic dyspnea. She was initially diagnosed with corticosteroid-resistant cryptogenic organizing pneumonia based on the radiological findings on her CT chest. Her symptoms did not improve, and she suffered from intolerable corticosteroid-related side effects. Reviews of systems were positive for arthritis and Raynaud's phenomenon. She was found to have elevated inflammatory markers and autoantibodies such as anti-Jo-1, anti-RO-52, and anti-SSA. A diagnosis of AS-ILD resistant to corticosteroid therapy was made. Her lung function improved with combination therapy of mycophenolate and rituximab. Our case highlights that a detailed history and physical exam, compatible radiologic imaging, and autoantibodies are essential for the diagnosis of AS-ILD.

Rituximab in Antimelanoma Differentiation-Associated Protein-5 Dermatomyositis with Interstitial Lung Disease

In this paper, we report a challenging case of a middle-age woman who developed antimelanoma differentiation-associated protein-5 dermatomyositis (anti-MDA5 DM) with interstitial lung disease (ILD) and was successfully treated with rituximab (RTX), after failure of a first-line therapy.

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.

The association between myositis-specific autoantibodies and muscle pathologies in idiopathic inflammatory myopathies

OBJECTIVE

To investigate specific muscle pathologies of different kinds of myositis-specific autoantibodies (MSAs) in idiopathic inflammatory myopathy (IIM) patients.

METHODS

One hundred eleven Chinese patients from Xiangya Hospital, Central South University diagnosed with IIMs according to European Neuromuscular Centre (ENMC) criteria were included. Clinical manifestation, myositis-specific autoantibodies, and histologic findings were evaluated to explore the pattern of necrosis, regeneration, and perifascicular atrophy, inflammatory cells in IIM patients with different MSAs.

RESULTS

Anti-SRP group has the lowest muscle strength scores, the highest creatine kinase levels, the most severe degree of necrosis and regeneration (1.90[0.80-3.95], 1.00[0.30-1.71]), and the lowest positive rate of MHC-I staining (35.71%). The anti-MDA5 group demonstrates the mildest pathological changes, with the fewest necrotic and regenerated muscle fibers (0.00[0.00-0.50], 0.00[0.00-0.00]), and the fewest inflammatory cell infiltration, and the highest muscle strength scores. The anti-NXP2 group has the most frequent inflammatory infiltrates, especially CD4+ T cells (31.14[15.00-39.00]). The patients with anti-NXP2 and the anti-TIF1γ antibodies show higher frequency of punched-out fibers (1.50[0.00-3.70], 0.00[0.00-1.00]) and perifascicular atrophy (71.43%, 55.56%). As for anti-synthetase antibodies (ASAs), the anti-Jo-1 group shows the most frequent rate of perifascicular necrosis (60%), while other ASA groups do not show perifascicular necrosis.

CONCLUSIONS

Of the MSAs, the anti-SRP antibody leads to the most severe muscle involvement, while the anti-MAD5 antibody the mildest. The anti-NXP2 and anti-TIF1γ groups have the most typical "DM" pathology. Key Points • Anti-SRP group shows severe muscle pathology while anti-MDA5 group shows the mildest. • Anti-NXP2 group has the most frequent inflammatory infiltrates. Pouch-out fibers and perifascicular atrophy are more prevalent in anti-NXP2 and anti-TIF1γ groups. • Anti-Jo-1 group is often accompanied by perifascicular necrosis, while other anti-synthetase antibody groups are not.

Immune Checkpoint Inhibitor-Related Myositis: From Biology to Bedside

Immune checkpoint inhibitor (ICI)-related inflammatory diseases, including polymyositis (PM) and dermatomyositis (DM), in patients suffering from neoplastic disorders represent a medical challenge. The treatment of these conditions has taken on new urgency due to the successful and broad development of cancer-directed immunological-based therapeutic strategies. While primary and secondary PM/DM phenotypes have been pathophysiologically characterized, a rational, stepwise approach to the treatment of patients with ICI-related disease is lacking. In the absence of high-quality evidence to guide clinical judgment, the available data must be critically assessed. In this literature review, we examine partially neglected immunological and clinical findings to obtain insights into the biological profiles of ICI-related PM/DM and potential treatment options. We show that differential diagnosis is essential to stratifying patients according to prognosis and therapeutic impact. Finally, we provide a comprehensive assessment of druggable targets and suggest a stepwise patient-oriented approach for the treatment of ICI-related PM/DM.

Weak Knees: A Case of Atorvastatin-induced Dermatomyositis

HMG-CoA reductase inhibitors (statins) are one of the most widely used medications in the primary care setting, and like any medications they have many side effects. The common ones include myalgias and rare ones include dermatomyositis. Here we present the case of atorvastatin-induced dermatomyositis with an unfortunate progression. This mandates a low threshold for first contact doctors to screen their patients for new-onset muscle weakness and rash after starting a statin recently, like our patient who had started atorvastatin several months before. This case adds to the previously reported cases and provides further evidence for statins being triggers of immune-mediated disease. The appropriate management of this condition requires a collaborative effort involving clinical judgment, laboratory testing, and imaging.

Autoantigens in the trabecular meshwork and glaucoma-specific alterations in the natural autoantibody repertoire

OBJECTIVES

Primary open-angle glaucoma (POAG) is a neurodegenerative disorder leading to a gradual vision loss caused by progressive damage to the optic nerve. Immunological processes are proposed to be involved in POAG pathogenesis. Altered serological autoantibody levels have been frequently reported, but complete analyses of the natural autoantibodies with respect to disease-related alterations are scarce. Here, we provide an explorative analysis of pathways and biological processes that may involve naturally immunogenic proteins and highlight POAG-specific alterations.

METHODS

Mass spectrometry-based antibody-mediated identification of autoantigens (MS-AMIDA) was carried out in healthy and glaucomatous trabecular meshwork (TM) cell lines, using antibody pools purified from serum samples of 30 POAG patients and 30 non-glaucomatous subjects. Selected antigens were validated by protein microarray (n = 120). Bioinformatic assessment of identified autoantigens, including Gene Ontology (GO) enrichment analysis and protein-protein interaction networks, was applied.

RESULTS

Overall, we identified 106 potential autoantigens [false discovery rate (FDR) < 0.01], from which we considered 66 as physiological targets of natural autoantibodies. Twenty-one autoantigens appeared to be related to POAG. Bioinformatic analysis revealed that the platelet-derived growth factor receptor beta (PDGFRB) pathway involved in TM fibrosis was particularly rich in POAG-related antigens. Antibodies to threonine-tRNA ligase (TARS), component 1 Q subcomponent-binding protein (C1QBP) and paraneoplastic antigen Ma2 (PNMA2) showed significantly (P < 0.05) higher levels in POAG patients as validated by protein microarray.

CONCLUSION

This study provides new insights into autoimmunity in health and glaucoma. Bioinformatic analysis of POAG-related autoantigens showed a strong association with the PDGFRB pathway and also increased levels of PNMA2, TARS, and C1QBP autoantibodies in the serum of POAG patients as potential glaucoma biomarkers.

A rare form of dermatomyositis associated with muscle weakness and normal creatine kinase level

We present a case study of a 61-year-old Vietnamese woman who presents with features of dermatomyositis (DM), including Gottron’s papules, heliotrope rash, cutaneous ulcers, generalised weakness and pain, and weight loss with normal levels of creatine kinase (CK). She demonstrated features of interstitial lung disease and subsequently tested positive for anti-melanoma differentiation-associated gene 5 and anti-small ubiquitin-like modifier 1 activating enzyme antibodies, which belong to a DM subtype known as clinically amyopathic dermatomyositis and do not present with raised CK. She received standard treatment for DM, including oral prednisolone, hydroxychloroquine, mycopheonlate and topical betamethasone. The treatment successfully reversed skin changes; however, the patient remained generally weak and unable to carry out her activities of daily living.

Myositis Specific Autoantibodies: A Clinical Perspective

Dermatomyositis (DM) is an idiopathic inflammatory condition characterized by myositis and variable skin manifestation. The existence of myositis specific autoantibodies usually manifests with varying degrees of skin or muscle inflammations. The condition has a well-established association with most clinical phenotypes, and these autoantibodies are useful in informing the diagnosis, management and prognosis of the disease. DM-specific autoantibodies include anti-MDA5, anti-NXP2, anti-SAE, anti-Mi-2, anti-ARS, anti-TIF1-gamma. Anti-Mi-2 antibodies are widely associated with DM cases that exhibit mainly cutaneous symptoms, such as cuticular overgrowths, Gottron's papules while being less susceptible to complications like interstitial lung disease or malignancy. The most distinct clinical features of patients with anti-SAE antibodies are their high prevalence of dysphagia and cutaneous manifestations that antecede the development of myopathies. In addition, DM patients with positive anti-PL-7 antibodies tend to have milder myositis characterized by low levels of creatine kinase as compared to patients with positive anti-Jo-1 antibodies. The anti-NXP2 antibodies are associated with transcriptional regulation and production of various proteins targeted by other DM antibodies, while anti- TIF1-γ. facilitates the transcription of deoxyribonucleic acids and regulates the growth and subsequent differentiation of body cells by controlling the signaling of TGF-β. The present review targets DM specific autoantibodies, considering their association, significance, and clinical presentation.

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.

Prevalence of other connective tissue diseases in idiopathic inflammatory myopathies

We sought to determine the prevalence of additional connective tissue diseases (CTDs) in patients with idiopathic inflammatory myopathies (IIM), and to study the muscle biopsy patterns in various clinico-serologic subsets of myositis. We undertook a retrospective cohort study of 648 patients with a histological diagnosis of IIM. The following was determined from the South Australian Myositis Database: presence of associated CTDs, histological details and presence of myositis-specific (MSA) or myositis-associated (MAA) antibodies. Among patients with IIM, a significantly greater proportion had systemic sclerosis 32/648 (4.9%) than mixed connective tissue disease (12/648, p = 0.003), primary Sjogren's syndrome (12/648, p = 0.003), systemic lupus erythematosus (10/648, p < 0.001) or rheumatoid arthritis (6/648, p = 0.0001). Polymyositis was the most common IIM diagnosis regardless of the presence or absence of CTD. MSA/MAA was more commonly detected in those with systemic sclerosis than those with IIM alone (OR 5.35, p < 0.005). The higher prevalence of SSc (compared with other CTDs) in IIM, together with the more frequent detection of autoantibodies in this group, suggests that these conditions may be linked.

Disease Specific Autoantibodies in Idiopathic Inflammatory Myopathies

Idiopathic inflammatory myopathies represent still a diagnostic and therapeutic challenge in different disciplines including neurology, rheumatology, and dermatology. In recent years, the spectrum of idiopathic inflammatory myopathies has been significantly extended and the different manifestations were described in more detail leading to new classification criteria. A major breakthrough has also occurred with respect to new biomarkers especially with the characterization of new autoantibody-antigen systems, which can be separated in myositis specific antibodies and myositis associated antibodies. These markers are detectable in approximately 80% of patients and facilitate not only the diagnostic procedures, but provide also important information on stratification of patients with respect to organ involvement, risk of cancer and overall prognosis of disease. Therefore, it is not only of importance to know the significance of these markers and to be familiar with the optimal diagnostic tests, but also with potential limitations in detection. This article focuses mainly on antibodies which are specific for myositis providing an overview on the targeted antigens, the available detection procedures and clinical association. As major tasks for the near future, the need of an international standardization is discussed for detection methods of autoantibodies in idiopathic inflammatory myopathies. Furthermore, additional investigations are required to improve stratification of patients with idiopathic inflammatory myopathies according to their antibody profile with respect to response to different treatment options.

Disorders of the Diaphragm

Pathologic processes that involve the central nervous system, phrenic nerve, neuromuscular junction, and skeletal muscle can impair diaphragm function. When these processes are of sufficient severity to cause diaphragm dysfunction, respiratory failure may be a consequence. This article reviews basic diaphragm anatomy and physiology and then discusses diagnostic and therapeutic approaches to disorders that result in unilateral or bilateral diaphragm dysfunction. This discussion provides a context in which disorders of the diaphragm and their implications on respiratory function can be better appreciated.

The spectrum and clinical significance of myositis-specific autoantibodies in Chinese patients with idiopathic inflammatory myopathies

OBJECTIVES

The aim of this study is to analyze the prevalence of myositis-specific autoantibodies (MSAs) and to elucidate their associations with clinical features in Chinese patients with polymyositis (PM) and dermatomyositis (DM).

METHODS

Twelve subsets of MSAs including anti-Mi-2, anti-TIF1-γ, anti-MDA5, anti-NXP2, anti-SAE1, anti-SRP, anti-Jo-1, anti-PL-7, anti-PL-12, anti-EJ, anti-OJ, and anti-HMGCR antibodies were tested. Four hundred and ninety-seven PM/DM patients were enrolled. Clinical features and laboratory data were collected. The frequency of MSAs and the correlations with clinical phenotypes were calculated by SPSS 21.0.

RESULTS

MSAs were present in 65.4% in PM/DM patients. Anti-TIF1-γ (14.3%), anti-MDA5 (12.5%), and anti-Jo-1 (10.1%) were the three commonest MSAs. Anti-SAE1 (OR 14.877, 95% CI 1.427-155.074), anti-SRP (OR 4.339, 95% CI 1.529-12.312) and anti-TIF1-γ (OR 2.790, 95% CI 1.578-4.935) were associated with dysphagia. In contrast, anti-MDA5 (OR 0.356, 95% CI 0.148-0.856) might decrease the frequency of this manifestation. Interstitial lung disease (ILD) was observed more frequently in patients carrying anti-EJ (OR 14.202, 95% CI 1.696-118.902), anti-Jo-1 (OR 11.111, 95% CI 3.306-37.335), and anti-MDA5 (OR 3.109, 95% CI 1.578-6.128). On the contrary, anti-Mi-2 (OR 0.180, 95% CI 0.055-0.589), anti-TIF1-γ (OR 0.163, 95% CI 0.080-0.333), and anti-HMGCR (OR 0.058, 95% CI 0.007-0.451) were protective factors against developing ILD. Anti-TIF1-γ was an independent risk factor for cancer-associated myositis (OR 4.237, 95% CI 1.712-10.487).

CONCLUSIONS

PM/DM patients had high frequencies of MSAs. Several MSAs were independent factors in determining unique clinical phenotypes.

Imaging in the diagnosis of idiopathic inflammatory myopathies; indications and utility

INTRODUCTION

Idiopathic inflammatory myopathies (IIM) are a heterogeneous group of muscle diseases that carry a significant morbidity and mortality risk. The utilization of imaging in the diagnostic pathway of IIM is therefore important to obtain early diagnosis and even monitor patients over time. Areas covered: Magnetic resonance imaging (MRI) has been the main imaging modality used to detect myositis but limitations include cost and accessibility, leading to delays in time to scan, and patient contraindications. This has led to the exploration of other imaging techniques to diagnose and monitor response to therapy. This article is based primarily on a literature search via PubMed using Boolean terms 'myositis' and the various imaging modalities. Expert opinion: Imaging is sensitive to pathology in IIM and may contribute to the diagnostic process. Learning how specific imaging features can distinguish different forms of IIM may allow more rapid diagnosis of myositis subtype and treatment planning, and to monitor disease activity particularly in patients who respond poorly to treatment. However, more work is needed to investigate the validity and relative utility of these imaging modalities.

Association of antinuclear antibody status with clinical features and malignancy risk in adult-onset dermatomyositis

BACKGROUND

The clinical significance of antinuclear antibody (ANA) status in adults with dermatomyositis (DM) has yet to be fully defined.

OBJECTIVE

We compared the incidence of amyopathic disease, risk of malignancy, and clinical findings in ANA⁺ and ANA^- patients with adult-onset DM.

METHODS

This was a retrospective cohort study of patients with ANA⁺ or ANA^- adult-onset DM determined by enzyme-linked immunosorbent assay.

RESULTS

Of 231 patients, 140 (61%) were ANA⁺ and 91 (39%) were ANA^-. Compared with the ANA^- patients, the ANA⁺ patients had a lower frequency of dysphagia (15% vs 26% [P = .033]) and heliotrope rash (38% vs 53% [P = .026]). In all, 54 patients (23%) developed malignancy within 3 years of diagnosis of their DM; 11% of the ANA⁺ patients developed malignancy versus 43% of the ANA^- patients (P < .001). There was a strong association between ANA positivity and lower likelihood of malignancy in multivariable analysis (odds ratio, 0.16; P < .001). Conversely, ANA positivity was not associated with amyopathic disease (odds ratio, 0.94; P = .87).

LIMITATIONS

The retrospective nature of the study was a limitation.

CONCLUSION

In patients with adult-onset DM, ANA negativity is associated with increased likelihood of development of malignancy within 3 years of diagnosis of their DM. Particularly close follow-up and frequent malignancy screening may be warranted in ANA^- individuals with DM.