Macrophage activation syndrome in MDA5 antibody-positive dermatomyositis and COVID-19 infection

The History of Macrophage Activation Syndrome in Autoimmune Diseases

In 1979, it became recognized in the literature that what we call hemophagocytic lymphohistiocytosis (HLH) was a nonmalignant disease of histiocytes. Subsequently a familial form and a secondary form of HLH were differentiated. When HLH is secondary to an autoimmune disease, rheumatologists refer to this entity as macrophage activation syndrome (MAS) to differentiate it from HLH itself. Although the first cases of MAS likely appeared in the literature in the 1970s, it was not until 1985 that the term activated macrophages was used to describe patients with systemic juvenile idiopathic arthritis (sJIA) complicated by MAS and the term macrophage activation syndrome first appeared in the title of a paper in 1993.MAS is one of the many types of secondary HLH and should not be confused with primary HLH. Experience has taught that MAS secondary to different autoimmune diseases is not equal. In the 30 years since initial description in patients with sJIA, the clinical spectrum, diseases associated with MAS, therapy, and understanding the pathogenesis have all made significant gains. The diagnostic/classification criteria for MAS secondary to sJIA, SLE, RA, and KD differ based on the different laboratory abnormalities associated with each (Ahn et al., J Rheumatol 44:996-1003, 2017; Han et al., Ann Rheum Dis 75:e44, 2016; Ravelli et al., Ann Rheum Dis 75:481-489, 2016; Borgia et al., Arthritis Rheumatol 70:616-624, 2018). These examples include the thrombocytosis associated with sJIA, a chronic generalized activation of the immune system, leading to elevations of fibrinogen and sIL-2R, low platelet count associated with SLE, and more acute inflammation associated with KD. Therefore, individual diagnostic criteria are required, and they all differ from the diagnostic criteria for HLH, which are based on a previously non-activated immune system (Ahn et al., J Rheumatol 44:996-1003, 2017; Han et al., Ann Rheum Dis 75:e44, 2016; Ravelli et al., Ann Rheum Dis 75:481-489, 2016; Borgia et al., Arthritis Rheumatol 70:616-624, 2018; Henter et al., Pediatr Blood Cancer 48:124-131, 2007). This helps to explain why the HLH diagnostic criteria do not perform well in MAS.The initial treatment remains high-dose steroids and IVIG followed by the use of a calcineurin inhibitor for resistant cases. IVIG can be used if there is a concern about malignancy to wait for appropriate investigations or with steroids. Interluekin-1 inhibition is now the next therapy if there is a failure to respond to steroids and calcineurin inhibitors. Advances in understanding the mechanisms leading to MAS, which has been greatly aided by the use of mouse models of MAS and advances in genome sequencing, offer a bright future for more specific therapies. More recent therapies are directed to specific cytokines involved in the pathogenesis of MAS and can lead to decreases in the morbidity and mortality associated with MAS. These include therapies directed to inhibiting the JAK/STAT pathway and/or specific cytokines, interleukin-18 and gamma interferon, which are currently being studied in MAS. These more specific therapies may obviate the need for nonspecific immunosuppressive therapies including high-dose prolonged steroids, calcineurin inhibitors, and etoposide.

Environmental exposures as risk factors for idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIM) are a heterogeneous group of rare autoimmune diseases, with increasing incidence rates observed in the recent years. The pathogenesis of IIM remains not fully understood, and the interaction of genetic and environmental factors is suspected. It is unclear whether the observed upward trend in the IIM incidence is solely due to improved access to effective diagnostics or perhaps due to increased exposure to external risk factors. The PUBMED database was thoroughly searched for articles describing environmental exposures potentially triggering the onset of IIM. The article summarizes the current knowledge available on this subject, taking into account various environmental factors, including among others UV radiation, infectious agents with SARS-CoV-2, inhaled particles, or iatrogenic effects. Limitations and unmet needs requiring further studies were highlighted.

Clinical and HRCT features of amyopathic dermatomyositis associated with interstitial lung disease: A retrospective study of 128 patients with connective tissue disease-related interstitial lung disease

BACKGROUND

This study retrospectively analyzed the laboratory data and chest images of patients with amyopathic dermatomyositis associated with interstitial lung disease (ADM-ILD) and patients with other connective tissue disease-related ILDs (CTD-ILDs) to find a characteristic index for the early recognition of ADM-ILD and help clinicians consider the possibility of ADM-ILD as soon as possible.

METHODS

In our cohort study, the records of 128 Chinese patients with CTD-ILD, including 33 ADM-ILD patients, 37 rheumatoid arthritis (RA)-ILD patients, 33 primary Sjogren's syndrome (pSS)-ILD patients, 14 systemic sclerosis (SSc)-ILD patients and 11 systemic lupus erythematosus (SLE)-ILD patients. The patients' clinical features, laboratory parameters, and chest HRCT findings were analyzed.

RESULTS

ADM-ILD patients generally had significantly higher LDH (333.52±160.21 U/L), AST (66.21±83.66 U/L), and CK-MB (18.23±8.28 U/L) levels than other CTD-ILD patients. A total of 90.91% (30/33) of ADM-ILD patients had elevated LDH. Patients with ADM-ILD were more prone to organizing pneumonia radiologic patterns on chest HRCT scans than patients with other CTD-ILDs (χ²=37.39, p < 0.001) and were found in 18 of 33 ADM-ILD patients. Anti-MDA5 (45.45%) was the most commonly detected autoantibody in ADM-ILD patients, followed by anti-PL-7 (21.21%), anti-Jo-1 (12.12%), and anti-PL-12 (9.09%), and levels of ALT (96.93±119.79 vs. 17.50±6.218 U/L), AST (113.00±106.13 vs. 23.56±6.91 U/L), LDH (415.00±198.51 vs. 261.94±67.75 U/L) and CK-MB (22.57±5.91 vs. 14.61±8.36 U/L) were significantly higher in anti-MDA5-positive patients, but these patients had significantly lower WBC counts (4.82±2.61 vs. 7.14±3.00 × 10⁹/L), lymphocyte counts (0.72±0.20 vs. 1.23±0.53 × 10⁹/L), and ALB levels (31.90±4.76 vs. 35.49±4.71 g/L).

CONCLUSIONS

ADM-ILD patients have higher serum LDH, AST and CK-MB levels, especially serum LDH levels, and are more prone to organizing pneumonia radiologic patterns on chest HRCT scans than other CTD-ILD patients. A high level of serum LDH with ILD may be a useful characteristic index for recognizing ADM-ILD.

A systematic review of the incidence, management and prognosis of new-onset autoimmune connective tissue diseases after COVID-19

A literature review on new-onset autoimmune connective tissue diseases (ACTDs) following COVID-19 is lacking. We evaluated potential associations between COVID-19 and the development of new-onset ACTDs. The "population" was adults with disease terms for ACTDs, including systemic lupus erythematosus (SLE), Sjogren's syndrome, systemic sclerosis (SSc), idiopathic inflammatory myositis (IIM), anti-synthetase syndrome, mixed CTD and undifferentiated CTD, and "intervention" as COVID-19 and related terms. Databases were searched for English-language articles published until September 2022. We identified 2236 articles with 28 ultimately included. Of the 28 included patients, 64.3% were female, with a mean age was 51.1 years. The USA reported the most cases (9/28). ACTD diagnoses comprised: 11 (39.3%) IIM (including four dermatomyositis); 7 (25%) SLE; four (14.3%) anti-synthetase syndrome; four (14.3%) SSc; two (7.1%) other ACTD (one lupus/MCTD overlap). Of eight, four (14.3%) patients (including that with lupus/MCTD) had lupus nephritis. The average time from COVID-19 to ACTD diagnosis was 23.7 days. A third of patients were admitted to critical care, one for treatment of haemophagocytic lymphohistiocytosis in SLE (14 sessions of plasmapheresis, rituximab and intravenous corticosteroids) and nine due to COVID-19. 80% of patients went into remission of ACTD following treatment, while three (10%) patients died-one due to macrophage activation syndrome with anti-synthetase syndrome and two from unreported causes. Our results suggest a potential association between COVID-19 and new-onset ACTDs, notably in young females, reflecting more comprehensive CTD epidemiology. The most common diagnosis in our cohort was IIM. The aetiology and mechanisms by which ACTDs emerge following COVID-19 remain unknown and require further research.

Rare complications of anti-melanoma differentiation-associated gene 5 antibody-positive dermatomyositis: Time to nip them in the bud

Anti-melanoma differentiation-associated gene 5 antibody-positive dermatomyositis (MDA5+ DM) is an infrequent autoimmune disease, which mainly distributes in Asians and females. MDA5+ DM usually presents various skin lesions and positive anti-MDA5 antibody (a myositis-specific autoantibody for itself) with amyopathic or hypomyopathic features. For MDA5+ DM patients, rapidly progressive interstitial lung disease is a common complication with a high-speed deterioration and a poor prognosis. Besides, there are other complications of MDA5+ DM patients, including pneumomediastinum, macrophage activation syndrome and spontaneous intramuscular hemorrhage. These complications were rare but lethal, so it is necessary to explore their diagnosis methods, therapies and potential mechanisms, which are helpful for early diagnoses and timely treatment. To date, several cases and studies have shown distinctive features, diagnoses and treatments of these three rare complications, and there are also some differences among them. In this review, we outlined the characteristics, administration and potential pathogenesis of these rare complications of MDA5+ DM.

New-onset dermatomyositis following SARS-CoV-2 infection and vaccination: a case-based review

Dermatomyositis is a rare, type I interferon-driven autoimmune disease, which can affect muscle, skin and internal organs (especially the pulmonary system). In 2021, we have noted an increase in new-onset dermatomyositis compared to the years before the SARS-CoV-2 pandemic in our center. We present four cases of new-onset NXP2 and/or MDA5 positive dermatomyositis shortly after SARS-CoV-2 infection or vaccination. Three cases occurred within days after vaccination with Comirnaty and one case after SARS-CoV-2 infection. All patients required intensive immunosuppressive treatment. MDA5 antibodies could be detected in three patients and NXP2 antibodies were found in two patients (one patient was positive for both antibodies). In this case-based systematic review, we further analyze and discuss the literature on SARS-CoV-2 and associated dermatomyositis. In the literature, sixteen reports (with a total of seventeen patients) of new-onset dermatomyositis in association with a SARS-CoV-2 infection or vaccination were identified. Ten cases occurred after infection and seven after vaccination. All vaccination-associated cases were seen in mRNA vaccines. The reported antibodies included for instance MDA5, NXP2, Mi-2 and TIF1γ. The reviewed literature and our cases suggest that SARS-CoV-2 infection and vaccination may be considered as a potential trigger of interferon-pathway. Consequently, this might serve as a stimulus for the production of dermatomyositis-specific autoantibodies like MDA5 and NXP2 which are closely related to viral defense or viral RNA interaction supporting the concept of infection and vaccination associated dermatomyositis.

Anti-MDA5 Antibody Linking COVID-19, Type I Interferon, and Autoimmunity: A Case Report and Systematic Literature Review

Introduction

The SARS-CoV-2 infection has been advocated as an environmental trigger for autoimmune diseases, and a paradigmatic example comes from similarities between COVID-19 and the myositis-spectrum disease associated with antibodies against the melanoma differentiation antigen 5 (MDA5) in terms of clinical features, lung involvement, and immune mechanisms, particularly type I interferons (IFN).

Case Report

We report a case of anti-MDA5 syndrome with skin manifestations, constitutional symptoms, and cardiomyopathy following a proven SARS-CoV-2 infection.

Systematic Literature Review

We systematically searched for publications on inflammatory myositis associated with COVID-19. We describe the main clinical, immunological, and demographic features, focusing our attention on the anti-MDA5 syndrome.

Discussion

MDA5 is a pattern recognition receptor essential in the immune response against viruses and this may contribute to explain the production of anti-MDA5 antibodies in some SARS-CoV-2 infected patients. The activation of MDA5 induces the synthesis of type I IFN with an antiviral role, inversely correlated with COVID-19 severity. Conversely, elevated type I IFN levels correlate with disease activity in anti-MDA5 syndrome. While recognizing this ia broad area of uncertainty, we speculate that the strong type I IFN response observed in patients with anti-MDA5 syndrome, might harbor protective effects against viral infections, including COVID-19.