anti-SAE Antibodies Research Articles

Juvenile dermatomyositis with Anti-SAE antibodies in a Moroccan child associated with pseudo-angioedema: a case report

BackgroundJuvenile Dermatomyositis (JDM) is the leading cause of non-infectious inflammatory myopathy in children. It is a heterogeneous group of autoimmune diseases characterized by a variable combination of muscular, dermatological, and visceral involvement. Myositis-specific autoantibodies help define homogeneous subgroups with common clinical characteristics and prognoses. Anti-SAE (small ubiquitin-like modifier 1 (SUMO-1) activating enzyme) antibodies are among the most recently discovered specific autoantibodies. The presence of these antibodies is very rare, making it challenging to define clinical features and prognosis in the juvenile form. We report the first case of an African patient with juvenile dermatomyositis and positive anti-SAE antibodies.Case ReportA 5-year-3-month-old Moroccan boy presented to the pediatric emergency department with dysphagia that had been evolving for two days, preceded two months earlier by facial erythema associated with fatigue, lower limb pain, difficulty walking, and progressive inflammatory polyarthralgia. On admission, the child had a heliotrope rash with predominant pseudo-angioedema on the lips, periungual telangiectasia, and Gottron’s papules over the bilateral interphalangeal and metatarsophalangeal joints. The patient had a more pronounced proximal muscle weakness in the lower limbs. He had no urticaria, fever, arthritis, calcinosis, cutaneous ulcers, or lipodystrophy. The Joint examination was normal, as was the pleuropulmonary examination. The electroneuromyography showed myogenic changes in all four limbs. Laboratory findings showed elevated levels of creatine phosphokinase and lactate dehydrogenase and a mild inflammatory syndrome. The electrocardiogram was normal. The anti-SAE antibodies were positive. The boy was diagnosed with juvenile dermatomyositis. He received methylprednisolone bolus therapy followed by oral prednisone. The latter was gradually tapered in combination with weekly intramuscular methotrexate. As a result, dysphagia disappeared within 48 h. After two weeks, there was an improvement in the muscular score and a significant regression of facial pseudo-angioedema.ConclusionWe report the first African patient with anti-SAE autoantibody-positive JDM. He had a typical dermatological manifestation of JDM associated with pseudo-angioedema predominant on the lips; a rarely reported sign in DM and JDM patients. The patient responded well to corticosteroid therapy and methotrexate.

Anti-SAE dermatomyositis: clinical and histologic characteristics from a monocentric Italian cohort.

Multiple myositis-specific antibodies have been identified, each associated with different clinical subsets of dermatomyositis (DM). Anti-SAE associated DM is considered the least studied subset. Our study aimed to evaluate the clinical and histological characteristics of DM patients with anti-SAE antibodies. As reference, patients with anti-Mi2 antibodies associated DM, representing a well-characterised subset, were analysed. We recorded data from our DM cohort in the INflammatory MYositis REgistry (INMYRE). Patients were divided into two groups: those positive for anti-SAE and those positive for anti-Mi2 antibodies. Clinical characteristics, including skin, muscle, and extra-muscular involvements, were recorded. Available muscle biopsies were compared between the two groups. Of 92 DM patients, 10 (10.9%) were positive for anti-SAE and 17 (18.5%) for anti-Mi2. Anti-SAE positive DM patients showed classic DM findings but were characterised by a higher prevalence of skin itching (60% vs. 11.8%, p<0.01), shawl sign (40% vs. 5.9%, p<0.05) and lung involvement (30% vs. 0%, p<0.05) compared to anti-Mi2 positive patients. Furthermore, anti-SAE positive DM patients showed lower creatine kinase levels than those with anti-Mi2 (median [IQR]: 101 [58-647] vs. 1984 [974-3717], p<0.05) and a lower percentage of muscle fibre degeneration and necrosis (1.5%±1.7 vs. 5.9%±3.2, p<0.05) in muscle biopsies. No other differences were observed. Anti-SAE DM represents a disease subset characterised by classic cutaneous involvement often associated with itching, less severe muscle involvement, but potential pulmonary involvement that should always be investigated in these patients.

Antibodies against Small Ubiquitin-like Modifier Activating Enzyme May Be a Protective Factor from Rapid Progressive Interstitial Lung Disease in Patients Bearing Antibodies against Melanoma Differentiation Associated Gene 5

Background: Anti-MDA5 antibody-bearing (anti-MDA5+)-dermatomyositis (DM) or polymyositis (PM) is notorious for causing rapidly progressive interstitial lung disease (RPILD) and/or cancers with high mortality rate. However, anti-MDA5 antibodies (Abs) are also found in other connective tissue diseases and their link with RPILD, especially with regard to the mortality rate, are unknown. Methods: We retrospectively recruited 71 patients bearing anti-MDA5-Abs in serum, stratified them in terms of a presence or absence of RPILD, and evaluated their clinical features, laboratory findings, associated myositis antibodies, concurrent connective tissue disease (CTD) as well as newly developed malignancies. Results: In total, 39 (55%) patients presented with DM/PM, but 32 (45%) did not. In total, 22 of the former and 11 of the latter developed RPILD eventually, accounting for a total of 46% of all MDA-5 bearing patients. On the other hand, 15 of all 71 (21.1%) patients had cancers. Among the 32 patients who did not have DM/PM, 27 (38.0% of all 71) had other CTDs, indicating that only 5 (7.0% of 71) patients did not have CTDs. Senility (odds ratio (OR) = 1.816, p = 0.032), presence of anti-Ro-52 antibody (OR = 1.676, p = 0.018), elevated C-reactive protein (CRP, OR = 4.354, p &lt; 0.001) and carcinoembryonic antigen (CEA, OR = 2.625, p = 0.005) posed risks for RPILD. High lactose dehydrogenase (LDH, p = 0.009), CRP (p = 0.001) and CEA (p = 0.001), ferritin (p ≤ 0.001) and low albumin (p ≤ 0.001) were significantly associated with mortality. Anti-SAE antibodies were negatively correlated with RPILD as analyzed by univariate (OR = 0.245, p = 0.017) and multivariate (OR = 0.058, p = 0.036) regressions, indicating that they may be a protective factor in relation to RPILD (OR = 0.543, p = 0.008) or fatality (OR = 0.707, p = 0.012), which was also demonstrated in subgroup analyses. Conclusions: In contrast to various risk factors for RPILD or mortality, anti-SAE antibodies might conversely be a protective factor in anti-MDA5+ patients.

Cancer associated autoantibodies in idiopathic inflammatory myopathies: A retrospective cohort from a single center in China

ObjectivesIdiopathic inflammatory myopathies (IIMs) are systemic, heterogeneous diseases, which mainly affect skeletal muscle. Myositis with cancer is often referred to as cancer-associated myositis (CAM), which is associated with poor prognosis. This study aimed to determine the cancer associated myositis-specific autoantibodies (MSAs) and to elucidate their associations with clinical features in Chinese patients with IIMs. MethodsThis retrospective study enrolled 312 patients with IIMs who were treated at Tianjin Medical University General Hospital, China, from January 2015 to December 2020. Clinical data were collected. Serum MSAs, including anti-Mi-2, anti-TIF1-γ, anti-NXP2, anti-SAE, anti-MDA5, anti-SRP, anti-Jo-1, anti-PL-7, anti-PL-12, anti-OJ, anti-EJ and anti-HMGCR antibodies were detected. Cancer-associated MSAs, their phenotypic and survival features were estimated through SPSS 20.0. ResultsThe results revealed that anti-TIF1-γ antibody and anti-SAE antibody were cancer-associated autoantibodies with odds ratios (95% CI) of 8.70 (3.35–22.64) and 22.31 (4.32–115.05), respectively. Skin lesions, proximal weakness, dysphagia and dysarthria were observed more frequently in patients carrying anti-TIF1-γ antibody. By contrast, patients with anti-TIF1-γ antibody had a lower frequencies of fever, arthritis/arthralgia and interstitial lung disease (ILD). Anti-TIF1-γ antibody positive CAM comprised about half of CAM entities and had the characteristic of close temporal association with cancer detection/recurrence. Female-dominant, common reproductive system tumors were other clinical features of this subset. Besides, patients with anti-TIF1-γ antibody positive had significantly lower survival rates than the anti-TIF1-γ antibody negative group. ConclusionsAnti-TIF1-γ antibody and anti-SAE antibody were cancer-associated autoantibodies. Anti-TIF1-γ antibody positive CAM was a subset that comprised about half of CAM entities and had the characteristic of poor prognosis.

Juvenile dermatomyositis associated with autoantibodies to small ubiquitin-like modifier activating enzyme: a report of 4 cases from North India and a review of literature.

Juvenile dermatomyositis (JDM) is the commonest inflammatory myositis in children. The clinical phenotype is often characterized by the presence of myositis-specific antibodies (MSA). Antibodies to small ubiquitin-like modifier activating enzyme (SAE) are amongst the rarest MSA reported in children. A review of medical records of all patients diagnosed to have JDM during the period January 1992-April 2022 in our institute was done. Case records of children with JDM who had significant positivity for anti-SAE antibody by myositis immunoblot were analysed in detail. Of the 140 children with JDM, MSA immunoblot was carried out in 53 patients-4 (7.5%) amongst these had significant positivity for anti-SAE antibodies. Median age of onset of symptoms was 5.5years (range: 5-11years). Clinical features at presentation included fever, photosensitivity, heliotrope rash, and Gottron papules. Clinically significant proximal muscle weakness was noted in 3/4 patients; 1 had no discernible weakness but had radiological evidence of myositis. None of the 4 patients had evidence of interstitial lung disease or calcinosis. All patients were treated with intravenous pulse methylprednisolone: subcutaneous weekly methotrexate and hydroxychloroquine. One patient received mycophenolate mofetil because of a relapse of muscle disease, while none received cyclophosphamide or biologics. Median follow-up duration was 21.5months (range: 6-39months). Anti-SAE antibodies were found in 4/53 (7.5%) of North Indian children with JDM. All 4 patients had predominant cutaneous manifestations followed by muscle disease. Response to treatment was brisk and sustained. None had developed calcinosis in the follow-up. 1. We report high prevalence of anti-SAE antibody positivity (7.5%) in North Indian cohort of JDM. 2. Cutaneous disease precedes muscle weakness in children with anti-SAE positive JDM. 3. No evidence of interstitial lung disease/calcinosis was seen in these children.

VP.46 Dermatomyositis-specific autoantibodies and muscle MRI findings

To date, 5 dermatomyositis specific autoantibodies (DMSAs) have been identified. Recent studies have revealed that each DM subtype according to the positive DMSA has clinical and pathological characteristic features, which naturally raises a question whether each DM subtype has unique features also on muscle MRI. We studied muscle MRI of 125 patients who had one of the 5 DMSAs and were pathologically diagnosed with DM by sarcoplasmic MxA expression at our center from January 2009 to November 2021. A total of proximal 12 leg and 8 arm muscles were evaluated in the axial plane, in addition to fascia and subcutaneous fat (SF). For skeletal muscle, the intensity (faint or strong), distribution (diffuse, patchy, or peripheral), percent area of affected (none, below 50%, more than 50%), and the texture (honeycomb pattern, homogeneous, or heterogeneous) of high signal intensity (HSI) within each muscle were evaluated. We graded the scores 0-3 according to the percent area of HSI in fascia and the scores 0-2 according to the HSI in SF. Among 125 patients, 79 were women, 32 were children (< 18years), and the median age were 54 years. Of these patients, 42 had anti-TIF1-γ, 16 anti-Mi-2, 16 anti-MDA5, 44 anti-NXP2, and 7 anti-SAE antibodies, respectively. Anti-TIF1-γ DM was associated with peripheral distribution of HSI (97.6% vs non- TIF1-γ DM 77.1%; p < 0.01). Anti-NXP2 DM was associated with diffuse distribution of HSI (97.7% vs 76.5%; p < 0.01) and high fascia score (p < 0.05). Anti-MDA5 DM was reversely associated with diffuse distribution of HSI (31.3% vs 91.7%; p < 0.001) and honeycomb pattern (62.5% vs 99.1%; p < 0.001), while it tended to have patchy distribution of HSI (56.3% vs 31.2%; p = 0.057). All DM patients had at least one HSI area in fascia. Each DM subtype according to positive DMSA seems to have characteristic MRI features, except for anti-SAE DM whose sample number was too small in this study. Fascial edema is common among DM patients.

Cancer associated autoantibodies in idiopathic inflammatory myopathies: A retrospective cohort from a single center in China

ObjectivesIdiopathic inflammatory myopathies (IIMs) are systemic, heterogeneous diseases, which mainly affect skeletal muscle. Myositis with cancer is often referred to as cancer-associated myositis (CAM), which is associated with poor prognosis. This study aimed to determine the cancer associated myositis-specific autoantibodies (MSAs) and to elucidate their associations with clinical features in Chinese patients with IIMs. MethodsThis retrospective study enrolled 312 patients with IIMs who were treated at Tianjin Medical University General Hospital, China, from January 2015 to December 2020. Clinical data were collected. Serum MSAs, including anti-Mi-2, anti-TIF1-γ, anti-NXP2, anti-SAE, anti-MDA5, anti-SRP, anti-Jo-1, anti-PL-7, anti-PL-12, anti-OJ, anti-EJ and anti-HMGCR antibodies were detected. Cancer-associated MSAs, their phenotypic and survival features were estimated through SPSS 20.0. ResultsThe results revealed that anti-TIF1-γ antibody and anti-SAE antibody were cancer-associated autoantibodies with odds ratios (95% CI) of 8.70 (3.35–22.64) and 22.31 (4.32–115.05), respectively. Skin lesions, proximal weakness, dysphagia and dysarthria were observed more frequently in patients carrying anti-TIF1-γ antibody. By contrast, patients with anti-TIF1-γ antibody had a lower frequencies of fever, arthritis/arthralgia and interstitial lung disease (ILD). Anti-TIF1-γ antibody positive CAM comprised about half of CAM entities and had the characteristic of close temporal association with cancer detection/recurrence. Female-dominant, common reproductive system tumors were other clinical features of this subset. Besides, patients with anti-TIF1-γ antibody positive had significantly lower survival rates than the anti-TIF1-γ antibody negative group. ConclusionsAnti-TIF1-γ antibody and anti-SAE antibody were cancer-associated autoantibodies. Anti-TIF1-γ antibody positive CAM was a subset that comprised about half of CAM entities and had the characteristic of poor prognosis.

A multianalyte assay for the detection of dermatomyositis-related autoantibodies based on immunoprecipitation combined with immunoblotting.

To develop a multianalyte assay for the detection of dermatomyositis (DM)-related autoantibodies using immunoprecipitation (IP) combined with immunoblotting (IB). Sera from 116 DM patients were subjected to RNA and protein immunoprecipitation assays as well as commercial enzyme-linked immunosorbent assays (ELISAs) for anti-aminoacyl transfer RNA synthetase, anti-melanoma differentiation antigen 5 (MDA5), anti-Mi-2, anti-transcriptional intermediary factor-1γ (TIF-1γ), and anti-U1 ribonucleoprotein antibodies. The IP/IB assay was developed by immunoprecipitation of autoantigens from HeLa cell extracts using patient sera, followed by immunoblotting with an antibody against Mi-2, TIF-1γ, OJ, nuclear matrix protein (NXP)-2, MDA5, PM/Scl, small ubiquitin-like modifier activating enzyme (SAE), or Ku. A multianalyte assay was designed by mixing primary antibodies in the IP/IB assay. IP assays identified any DM-related autoantibodies in 100 patients (86%), of which 82% were covered by commercial ELISAs, with a false-positive result in two sera and a false-negative result in one serum. The results obtained from the multianalyte IP/IB assay and 'gold-standard' IP assays were concordant in terms of the presence or absence of anti-MDA5, anti-TIF-1γ, anti-OJ, anti-NXP-2, anti-PM/Scl, anti-SAE, anti-Mi-2, and anti-Ku antibodies. This multianalyte IP/IB assay combined with commercial ELISAs is an alternative to 'gold-standard' IP assays for the detection of DM-related autoantibodies.

Recent research on myositis-specific autoantibodies in juvenile dermatomyositis.

Juvenile dermatomyositis (JDM) is an autoimmune disease manifesting as proximal muscle weakness and skin rash and can involve multiple systems and visceral organs. Myositis-specific autoantibodies (MSAs) are highly associated with various complications and prognosis in JDM. Patients with anti-Mi-2 antibodies tend to have good prognosis and typical clinical symptoms. Patients with anti-MDA5 antibodies often have diffuse interstitial lung disease and skin ulcer, with mild symptoms of myositis. Patients with anti-NXP2 antibodies often have calcinosis, and such antibodies are associated with gastrointestinal bleeding and perforation. Patients with anti-TIF1-γ antibodies have diffuse and refractory skin lesions. Anti-SAE antibodies are rarely detected in children, with few reports of such cases. This article reviews the features of clinical phenotypes in JDM children with these five types of MSAs, so as to provide a basis for the clinical treatment and follow-up management of children with JDM.

Clinical significance of radiological patterns of HRCT and their association with macrophage activation in dermatomyositis.

To evaluate the distribution of radiological characteristics stratified by different myositis-specific autoantibodies, identify prognostic value of high-resolution CT (HRCT) patterns in DM-associated interstitial lung disease (DM-ILD), and explore the possible mechanism associated with macrophage activation. We enrolled 165 patients with PM/DM-ILD. The distribution of HRCT radiological types with different myositis-specific autoantibodies and the relationship between radiological features and ILD course and prognosis were analysed. Additionally, the potential role of macrophage activation in rapidly progressive ILD (RP-ILD) with DM was studied. The organizing pneumonia pattern was dominant in HRCT findings of patients with DM-ILD, especially those with anti-SAE (6/6, 100%) and anti-MDA5 (46/62, 74.2%) antibodies. The ratios of organizing pneumonia and nonspecific interstitial pneumonia patterns were almost equal in patients with aminoacyl tRNA synthetase antibodies, and nonspecific interstitial pneumonia pattern was associated with a mild clinical course. Lower lung zone consolidation in HRCT was related to RP-ILD in both anti-MDA5 and anti-aminoacyl tRNA synthetase antibody-positive groups. Ferritin levels of >1000 ng/ml (odds ratio (OR), 12.3; P=0.009), elevated carcinoembryonic antigen (OR, 5.8; P=0.046) and carbohydrate antigen 19-9 (OR, 7.8; P=0.018) were independent predictors of a lower lung zone consolidation pattern in anti-MDA5 antibody-positive DM. The infiltration of CD163-positive macrophages into alveolar spaces was significantly higher in the DM-RP-ILD group than in the chronic DM-ILD group. HRCT patterns are different among variable myositis-specific autoantibodies positive patients with ILD and lower zone consolidation in HRCT correlated with RP-ILD in DM. Activated macrophages may contribute to the pathogenesis of RP-ILD in DM.

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

The role of cancer-associated autoantibodies as biomarkers in paraneoplastic myositis syndrome.

The aim of this study is to provide a comprehensive overview of the current insight about the clinical utility of cancer-associated autoantibodies (CAAs) as biomarkers in paraneoplastic myositis syndrome (PMS). In addition, the possible mechanisms of the relationship between malignancy and myositis onset are discussed. It has become increasingly clear that a subgroup of the myositis-specific autoantibodies could be considered as CAAs because they are closely related to the PMS. Increased risk of cancer was found in patients with antitranscriptional intermediary factor 1-γ (TIF1-γ), antinuclear matrix protein-2 (NXP-2), anti3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) or antismall ubiquitin-like modifier 1-activating enzyme (SAE) antibodies. However, the diagnosing sensitivity and specificity of these CAAs for PMS are different among different cohort studies. Abnormally expressed or mutated autoantigen genes in tumor could possibly induce cross immunity against self-proteins and subsequently lead to the development of PMS. Anti-TIF1-γ, anti-NXP-2, anti-HMGCR and anti-SAE antibodies may act as CAAs in PMS. It is necessary to closely screen and monitor for cancer in patients with CAAs. The recent studies of the relationship between CAAs and PMS provided important new insights into the disease mechanisms.

11. An unusual case of dermatomyositis with anti-small ubiquitin-like modifier activating enzyme (SAE) antibodies present

IntroductionIdiopathic inflammatory myopathies (IIM) have long been diagnosed using a defined number of clinical criteria (Bohan and Peter). The emergence of new myositis specific antibodies (MSAs) and their relation to specific disease phenotypes may be useful in establishing a new clinical-serological diagnostic criteria for different disease presentations and thus help to determine management and prognosis. We present a case of dermatomyositis (DM) where limb subcutaneous oedema; a rare manifestation of the disease, and severe dysphagia were prominent clinical features in addition with the presence of anti-small ubiquitin-like modifier activating enzyme (SAE) antibodies.Case descriptionA 63-year-old Pakistani male presented with weight loss, anorexia, odynophagia, and a rash over his scalp, chest, face and flexor surfaces. Initial blood results revealed hypoalbuminaemia, CRP 7mg/L and ESR 37mm/h. A CT chest revealed an anterior mediastinum soft tissue mass suggestive of necrosis, with multiple ill-defined nodes throughout the lungs.An endoscopy revealed severe gastritis. Oropharyngeal examination revealed pooling of saliva and mucositis. Ceftriaxone was commenced for a presumed infective aetiology.Video fluoroscopy confirmed pharyngeal dysphagia with aspiration. Examination demonstrated a non-fatigable bulbar sounding dysarthria. There was no tongue wasting or fasciculations. Power was globally reduced, with marked proximal upper and lower limb weakness.Nerve conduction studies revealed normal sensation, and most motor nerves had normal conduction velocities with small nerve responses. Electromyography showed areas with denervation.With no improvement in the patient’s condition, anti-tuberculosis and anti-fungal therapy were commenced, with pulsed methylprednisolone for three days followed by 80mg daily to cover for an organizing pneumonia. Subsequent cultures were negative.Progressive weight loss with muscle wasting ensued and later, facial hyperpigmentation was noted in addition to the development of facial, lip and arms swelling. He was rheumatoid factor positive >500 iu/ml, with a raised IgE 2912 g/L and IgG 37.6 g/L. A CT-PET scan revealed intense uptake in the muscles posterior of the neck, tongue and masticators.An MRI scan of his arms revealed several abnormal signals around the shoulder girdle, long muscles of the back, and upper arm, which guided the site for muscle biopsy. This revealed highly abnormal skeletal muscle with frequent atrophic and necrotic fibres overrun by macrophages and T-cell rich inflammation. These findings in addition to serology reporting the presence of anti-SAE antibodies confirmed the diagnosis.Pulsed methylprednisolone, immunoglobulin therapy, and azathioprine were initiated with reducing prednisolone dose.DiscussionThis case of DM with a generalised rash, severe dysphagia and limb subcutaneous oedema were salient features in addition to the presence of anti-SAE antibodies. Anti-SAE has been shown to be present exclusively in DM patients where rash and severe dysphagia are common clinical findings. Our patient presented with severe dysphagia, which can be difficult to manage requiring enteral feeding. Video fluoroscopy was particularly useful in this case helping to stratify the severity of dysphagia and we would urge other clinicians to use this tool when investigating patients with suspected dermatomyositis to avoid potential complications of poor swallow including aspiration pneumonia. The additional imaging modality of PET-CT in our case confirmed the involvement of the muscles of mastication thus could prove a useful tool when investigating involvement of swallowing muscles in patients with anti-SAE DM.Skin features are another common finding in the anti-SAE group and our patient had a heliotrophic rash and shawl sign, which responded poorly to treatment. We describe the additional feature of severe subcutaneous limb and facial oedema, a rare manifestation of the disease, described in only a few other cases. Limb subcutaneous oedema is thought to reflect underlying severe muscle disease, is difficult to treat, and often is unresponsive to conventional treatment. Our case, and several other cases with the presence of limb oedema as reported in a literature search, required treatment with intravenous immunoglobulin and glucocorticoids, in addition with azathioprine and methotrexate.This is the first reported case to our knowledge of a patient with positive ANA, RF, anti-ccp, and anti-small ubiquitin-like modifier activating enzyme (anti-SAE) antibodies.Key learning pointsThe finding of anti-SAE in our case where severe dysphagia was present provides further weight to this antibody being a useful serological marker to identify this subgroup of DM patients. Identifying this antibody may be helpful in creating management strategies for these patients and determining disease progression and prognosis.The presence of limb and facial oedema may be an overlying feature of the anti-SAE group; however, previous cases of limb oedema have not identified this antibody as the SAE test was unavailable. The presence of severe dysphagia and subcutaneous oedema suggests the presence of anti-SAE lends itself to a clinical phenotype of DM that is particularly severe and requires multidisciplinary input.Conflicts of interestThe authors have declared no conflicts of interest.

Clinical characteristics of anti-SAE antibodies in Chinese patients with dermatomyositis in comparison with different patient cohorts

This study aimed to analyze the clinical features of anti-SAE antibodies in Chinese myositis patients in comparison with different cohorts. The anti-SAE antibodies were tested in myositis patients and in control subjects. Long-term follow-up was conducted on the antibody-positive patients. Anti-SAE antibodies were exclusively present in 12 out of 394 (3.0%) adult dermatomyositis (DM) patients. Of the anti-SAE-positive DM patients, 75% had distinctive diffuse dark-red or pigment-like skin rashes, and 67% of these patients experienced mild muscle weakness. Muscular biopsies showed mild pathological manifestations. Compared with the antibody-negative group, the average age of dermatomyositis onset in the antibody-positive group was higher, and dysphagia occurred more frequently noted (p = 0.012). Only 9 patients received follow-up, 7 experienced improvement after treatment. The anti-SAE antibody levels correlated with improved disease condition. The anti-SAE antibody was found exclusively in adult DM patients, occurring infrequently in Chinese patients. In addition to a diffuse dark-red or pigment-like skin rash and mild muscular weakness, common symptoms included propensity for developing dysphagia. Serum levels of the anti-SAE antibody correlated with myositis disease activity, and anti-SAE-positive patients were responsive to treatment.

Recent advances in dermatomyositis-specific autoantibodies.

In dermatomyositis, disease-specific autoantibodies now cover more than 70% of patients. These autoantibodies closely correlate with distinct clinical manifestations. In the past few years, extensive evidence has been accumulated on clinical significance of dermatomyositis-specific autoantibodies including autoantibodies against melanoma differentiation antigen 5 (MDA5), transcriptional intermediary factor 1 (TIF1), nuclear matrix protein 2 (NXP2), and small ubiquitin-like modifier activating enzyme (SAE). Anti-MDA5 antibodies are found with high specificity in clinically amyopathic dermatomyositis presenting rapidly progressive interstitial lung disease (ILD) especially in Asian population. Similar tendency has been reported in the US/Europe, although the frequency of positivity and the type of ILD may differ. Anti-TIF1 antibodies are present in juvenile and adult dermatomyositis patients with close correlation with malignancy in adult population. Anti-NXP2 antibodies share similar phenotype with anti-TIF1 antibodies, except that anti-NXP2 antibodies are associated with calcinosis and severe muscle disease. Although numbers are still small, patients with anti-SAE antibodies tend to present skin disease first and then progress to muscle weakness with systematic symptoms including dysphagia. Moreover, distinct cutaneous manifestations and muscle histopathology findings for each autoantibody have been reported. 'Autoantibody-based classification' of dermatomyositis subsets is now a useful strategy for comprehending the heterogeneous spectrum of dermatomyositis.

Clinical and serological features of patients with dermatomyositis complicated by spontaneous pneumomediastinum

Objective To explore the clinical and serological features of patients with pneumom-diastinum (PNM) and dermatomyositis associated interstitial lung disease (DM-ILD). Methods A total of 145 polymyositis/dermatomyositis (PM/DM) patients hospitalized in our department from March, 2010 to December, 2012 were recruited. The sera, clinical and laboratory data were collected. Anti-aminoacyl-tRNA synthetase (anti-ARS) and anti-melanoma differentiation-associated gene 5 (MDA5) antibodies were detected by RNA-immunoprecipitation (RNA-IP) and ELISA, respectively. Anti-NXP2, anti-TIF1γ, anti-SRP, anti-SAE and anti-Mi2 antibodies were detected by immunoprecipitation-Western blotting. Variables were compared between DM patients with and without PNM, as well as between DM-ILD patients with and without PNM. Chi square test, Fisher's exact test, t test, Mann-Whitney U test and a multivariate logistic regression model were used for statistical analysis. Results A total of 11 DM patients (10 patients positive for anti-MDA5 and 1 patient positive for anti-Mi2) developed spontaneous PNM. No PM patient developed PNM. No differences of sex, age at the onset of DM, serum ferritin levels and C reactive protein (CRP) levels was observed between DM patients with and without PNM. Compared with DM patients without PNM, DM patients with PNM had significantly higher frequencies of rapidly progressive ILD (RP-ILD) (63.6% vs 24.4%, χ2=7.25, P=0.01), anti-MDA5 antibodies (90.9% vs 52.4%, χ2=5.86, P=0.02), clinically amyopathic DM (CADM) (63.6% vs 22.0%, χ2=8.57, P=0.007) and cutaneous ulcers (36.4% vs 11%, χ2=5.20, P=0.04), but significantly lower creatine kinase (CK) levels [58.5 (30.5, 394.3) U/L vs 284 (73.0, 917.0) U/L, t=207.5, P=0.04]. The logistic multivariate analysis indicated that cutaneous ulcer was the only independent risk factor for the occurrence of PNM in DM [OR=5.98, 95% confidence interval (CI) (1.12, 31.98), P=0.037]. In the comparisons between DM-ILD patients with and without PNM, a higher frequency of CADM was observed in the PNM group (63.6% vs 27.9%, χ2=5.37, P=0.03), but no significant difference of the frequencies of RP-ILD, anti-MDA5 antibodies, cutaneous ulcers and CK levels was found in these two groups. All patients with PNM were treated with corticosteroids and immunosuppressants. During the follow-up period, 6 patients died of respiratory failure. Conclusion Spontaneous PNM is a refractory complication with poor prognosis, and tends to occur in DM patients with RP-ILD, anti-MDA5 antibody, CADM diagnosis and low CK level, especially in patients with cutaneous ulcers. Key words: Dermatomyositis; Lung diseases, interstitial; Mediastinal emphysema

Low prevalence of anti-small ubiquitin-like modifier activating enzyme antibodies in dermatomyositis patients

Background. The myositis-specific autoantibodies that characterize certain forms of inflammatory myopathy are useful in diagnosing dermatomyositis (DM) / polymyositis and predicting its prognosis. Autoantibodies to small ubiquitin-like modifier activating enzyme (SAE) have been identified as a DM-marker antibody in European Caucasians. Objective and methods. This study investigates the frequency and clinical characteristics of anti-SAE autoantibodies in Japanese patients with DM. Sera from 110 Japanese patients, including 13 with juvenile DM, were screened for anti-SAE antibodies by enzyme-linked immunosorbent assays. Positive sera were further examined by immunoblotting of the immunoprecipitates. Results. Only two patients (1.8%) were confirmed to have anti-SAE antibodies, and neither of these two patients had amyopathic or juvenile DM. One patient with anti-SAE had DM complicated with pulmonary arterial hypertension, and the other had cancer-associated DM. Both had hallmark cutaneous manifestations of DM. Conclusion. This is the first report of anti-SAE antibodies from an Asian single center cohort. Although Japanese patients with anti-SAE antibodies have a clinical phenotype similar to that of Caucasian patients, their frequency was lower in the Japanese patients than in the previously reported Caucasian patients.

Anti-SAE antibodies in autoimmune myositis: Identification by unlabelled protein immunoprecipitation in an Italian patient cohort

IntroductionMyositis specific autoantibodies (MSAs) are useful in the diagnosis of idiopathic inflammatory myopathies and in the definition of disease subsets. The aim of this study was to set up an unlabelled protein immunoprecipitation technique for MSA identification in the sera of myositis patients, in order to identify and investigate new antibody reactivity, undetectable by currently used methods. MethodsSera of 183 patients with connective tissue diseases (75 adult dermatomyositis, 12 juvenile dermatomyositis, 43 polymyositis, 53 other connective tissue diseases) and 30 healthy controls were screened by an in-house procedure of unlabelled protein immunoprecipitation. In the same sera MSAs and myositis associated antibodies were determined by immunoblotting and immunoprecipitation for RNA. ResultsThe analytical specificity of unlabelled protein immunoprecipitation was demonstrated by testing reference sera with known antibody reactivity.Sera from five patients, affected with dermatomyositis (5/75=7%), immunoprecipitated two proteins of 40 and 90kDa apparent molecular weights respectively, consistent with the subunits of the small ubiquitin like modifier activating enzyme heterodimer (SAE1/SAE2). The identity of putative SAE immunoprecipitated proteins was confirmed by immunoblotting on immunoprecipitates using commercial monospecific antibodies to SAE1 and SAE2. Major clinical features were compared between anti-SAE positive and negative patients. Interestingly, anti-SAE positive patients had mainly skin and muscle manifestations while dysphagia, interstitial lung disease, arthritis and constitutional symptoms were absent. ConclusionsUnlabelled protein immunoprecipitation is a specific analytical approach, appropriate for the identification of the recently described anti-SAE autoantibody. We confirmed the role of anti-SAE antibody as marker of dermatomyositis.