Comparison of clinical features between patients with anti-synthetase syndrome and dermatomyositis: results from the MYONET registry

Epidemiology of myositis

PURPOSE OF REVIEW

This review aims to synthesize recent developments in the epidemiology of idiopathic inflammatory myopathies (IIMs), focusing on incidence, prevalence, disease classification, and clinical outcomes.

RECENT FINDINGS

IIM is a rare group of autoimmune diseases characterized by muscle weakness and systemic involvement, with incidence rates ranging from 0.2 to 2 cases per 100 000 person-years. The role of myositis-specific autoantibodies (MSAs) in stratifying disease risk and prognosis is increasingly recognized, such as in anti-MDA5 positive DM, which is associated with a high risk of rapidly progressive interstitial lung disease. Furthermore, patients with IIM exhibit elevated risks of comorbidities, including cardiovascular disease and malignancy.

SUMMARY

IIM diseases are complex disorders with significant health impacts, necessitating enhanced awareness and research. Improved classification and understanding of MSAs are crucial for earlier diagnosis and tailored therapeutic strategies. Continued epidemiological research is essential to elucidate underlying mechanisms and inform future interventions, ultimately aiming to enhance the quality of life and clinical outcomes for affected patients.

Disease activity in patients with idiopathic inflammatory myopathy according to time since diagnosis and positivity to antisynthetase autoantibodies: data from the Myo-Spain registry

OBJECTIVE

To evaluate the main outcomes of disease activity and their association with other measures of activity, damage, and quality of life in patients with idiopathic inflammatory myopathy (IIM) according to time since diagnosis and positivity to antisynthetase autoantibodies (ASAs).

METHODS

Cross-sectional multicenter study within the Spanish Myo-Spain registry. Cases were classified as incident (≤ 12 months since diagnosis) and prevalent. The main outcomes of disease activity were the Myositis Disease Activity Assessment visual analogue scale (MYOACT), the Manual Muscle Test 8 (MMT-8), physician global activity (PhGA), and extramuscular activity. Other measures of activity, damage, and quality of life included patient global disease activity, MYOACT muscular, creatine phosphokinase, Health Assessment Questionnaire, physician and patient global damage, global damage of the Myositis Damage Index, and the 12-item Short-Form Health Survey (SF-12). We analyzed associations using a multivariate generalized linear model and a simple linear regression model.

RESULTS

A total of 554 patients with different diagnostic subgroups of IIM were included (136 incident and 418 prevalent cases), with 215 ASA-positive patients (58 incident and 157 prevalent cases). All measures of disease activity were higher in the incident cases (p < 0.05), except for MYOACT muscular and creatine phosphokinase, for which no differences were recorded in ASA-positive patients. No differences were found between incident and prevalent cases for measures of damage. Values for the physical component of the SF-12 were higher in the prevalent cases (p < 0.05). The multivariate model was initially significant overall for the main activity outcomes. Positivity to ASAs was positively and negatively associated with the MYOACT index and MMT-8, respectively (p < 0.05), although no association was recorded with PhGA and extramuscular activity. Prevalent cases were negatively associated with the main outcomes of activity, except with MMT-8, for which the association was positive (p < 0.05).

CONCLUSIONS

The main activity outcomes validated in polymyositis and dermatomyositis could also be used in other subtypes of IIM, such as antisynthetase syndrome. Recent diagnosis is associated with greater disease activity, as assessed based on these activity outcomes. PhGA and extramuscular activity are not modified by ASA positivity, thus supporting their preferred use for assessing treatment response in IIM with ASAs.

Clinical and laboratory features between anti-TIF1γ dermatomyositis with and without malignancy: 37 case series and a review

We aimed to analyze the clinical profile and malignancy indicators in dermatomyositis (DM) with anti-transcriptional intermediary factor 1 antibody (anti-TIF1γ-Ab). A comparison was made between clinical information of anti-TIF1γ DM patients with and without malignancy. Additionally, a review of the literature on anti-TIF1γ DM and malignancy was conducted by searching PubMed and EMBASE databases. In our cohort of 37 patients, 27.0% (10/37) developed malignancy. The timeframe during which these 10 patients developed malignancy ranged from 21 months prior to the diagnosis of DM to 36 months following the diagnosis of DM. Specifically, one patient was diagnosed with breast cancer at the age of 36. Comparing the groups with and without malignancy, we found that age over 65 years (40% vs 7.4%, P = 0.035), a shorter duration from the onset of symptoms to the diagnosis of DM (2.5 vs 10 months, P = 0.003), and higher erythrocyte sedimentation rate (ESR) levels (23 vs 10 mm/h, P = 0.048) were found to be associated with an increased risk of malignancy. Conversely, the presence of Gottron's papules (63% vs 20%, P = 0.029) may suggest a lower likelihood of malignancy. The literature review revealed that the prevalence of myositis-associated malignancy was 40.7% (340/836), with variations ranging from 19% to 82.9% across different series. In summary, factors such as age over 65 years, a shorter duration between symptom onset and diagnosis of DM, and elevated ESR levels may indicate an increased risk of malignancy in anti-TIF1γ DM patients.

Anti-synthetase and myelodysplastic syndromes with deep morphea: an example of shared immunopathogenesis? A case-based review

Anti-synthetase syndrome (AS) is a subset of idiopathic inflammatory myopathy (IIM) characterized by the presence of anti-aminoacyl-transfer RNA synthetase accompanied by myositis, interstitial lung disease and other clinical features. According to a recent multicentric study, 31% of AS patients present skin lesions compatible with dermatomyositis, but sclerodermiform features are rare. Therefore, we aimed to report the case of a patient with simultaneous diagnosis of AS, deep morphea, vasculitic neuropathy, and myelodysplastic syndrome and review the current literature regarding these uncommon associations. A 57 year old man with axial and symmetrical proximal muscle weakness, skin thickening and B symptoms, later diagnosed with PL7 + AS, deep morphea, myelodysplastic syndrome (MDS) and vasculitic neuropathy documented by histopathologic studies and immunologic assessments. Since both AS and deep morphea share the vasculopathic changes and type II interferon-induced inflammation, we hypothesize that they may share pathogenic mechanisms. The muscle biopsy of the patient was consistent with AS and showed focal neutrophil infiltration. The patient received intensive immunosuppressive therapy for AS and vasculitic neuropathy, with high dose steroids, intravenous immunoglobulin (IVIg) and rituximab. Nonetheless, he suffered an unfavorable evolution with a fatal outcome due to septic shock. Albeit sclerodermiform features are rare in patients with AS, we propose a pathogenic link among AS, deep morphea and the autoimmune/autoinflammatory signs of MDS. The vasculopathic changes along with the activation of the innate and adaptive immune system leading to the production of proinflammatory cytokines may have been one of the contributing factors for the coexisting diagnosis of the patient.

A distinct immune landscape in anti-synthetase syndrome profiled by a single-cell genomic study

Objectives

The objective of this study was to profile the transcriptional profiles of peripheral blood mononuclear cells (PBMCs) and their immune repertoires affected by anti-synthetase syndrome (ASS) at the single-cell level.

Methods

We performed single-cell RNA sequencing (scRNA-seq) analysis of PBMCs and bulk RNA sequencing for patients with ASS (N=3) and patients with anti-melanoma differentiation-associated gene 5-positive dermatomyositis (MDA5+ DM, N=3) along with healthy controls (HCs, N=4). As ASS and MDA5+ DM have similar organ involvements, MDA5+ DM was used as a disease control. The immune repertoire was constructed by reusing the same scRNA-seq datasets. Importantly, flow cytometry was performed to verify the results from the scRNA-seq analysis.

Results

After meticulous annotation of PBMCs, we noticed a significant decrease in the proportion of mucosal-associated invariant T (MAIT) cells in ASS patients compared to HCs, while there was a notable increase in the proportion of proliferative NKT cells. Compared with MDA5+ DM patients, in their PBMCs ASS patients presented substantial enrichment of interferon pathways, which were primarily mediated by IFN-II, and displayed a weak immune response. Furthermore, ASS patients exhibited more pronounced metabolic abnormalities, which may in turn affect oxidative phosphorylation pathways. Monocytes from ASS patients appear to play a crucial role as receptive signaling cells for the TNF pathway. Immunophenotyping analysis of PBMCs from ASS patients revealed an increasing trend for the clone type CQQSYSTPWTF.

Conclusion

Using single-cell genomic datasets of ASS PBMCs, we revealed a distinctive profile in the immune system of individuals with ASS, compared to that with MDA5+ DM or healthy controls.