Interstitial Lung Disease-Complicated Anti-MDA5 Antibody in Clinically Amyopathic Dermatomyositis Patients: Report of Two Cases With Distinct Clinical Features

Innovations in the care of childhood interstitial lung disease associated with connective tissue disease and immune-mediated disorders

Childhood interstitial lung disease (chILD) associated with connective tissue and immune mediated disorders is the second most common chILD diagnostic category. As knowledge of the molecular and genetic underpinnings of these rare disorders advances, the recognized clinical spectrum of associated pulmonary manifestations continues to expand. Pulmonary complications of these diseases, including ILD, confer increased risk for morbidity and mortality and contribute to increased complexity for providers tasked with managing the multiple organ systems that can be impacted in these systemic disorders. While pulmonologists play an important role in diagnosis and management of these conditions, thankfully they do not have to work alone. In collaboration with a multidisciplinary team of subspecialists, the pulmonary and other systemic manifestations of these conditions can be managed effectively together. The goal of this review is to familiarize the reader with the classic patterns of chILD and other pulmonary complications associated with primary immune-mediated disorders (monogenic inborn errors of immunity) and acquired systemic autoimmune and autoinflammatory diseases. In addition, this review will highlight current, emerging, and innovative therapeutic strategies and will underscore the important role of multidisciplinary management to improving outcomes for these patients.

Anti-MDA5 antibody-positive dermatomyositis: pathogenesis and clinical progress

Anti-melanoma differentiation-associated protein 5 (MDA5) antibody-positive dermatomyositis (MDA5-DM) is a subtype of dermatomyositis. Although the aetiology and pathology remain unclear, increasing evidence suggests that viral infection is a potential trigger of MDA5-DM. Multiple factors, including T cells, B cells, neutrophils and macrophages, are implicated in the pathophysiology of MDA5-DM. Distinctive skin rashes, rapidly progressive interstitial lung disease, peripheral lymphopenia and elevated serum ferritin levels are the most prominent clinical and laboratory features of MDA5-DM. Concomitant infection is a common complication of MDA5-DM. The proper evaluation of patients with MDA5-DM requires knowledge of the disease heterogeneity and clinical course variability. Several biomarkers, including serum levels of anti-MDA5 antibodies and biomarkers related to macrophage activation, have been identified as useful tools for monitoring disease activity and prognosis. MDA5-DM shows a poor response to conventional glucocorticoid and immunosuppressant therapy and has a poor overall prognosis. Therefore, there is an urgent need to explore the key pathogenic mechanisms of MDA5-DM and develop novel therapeutic options for patients. This Review discusses recent clinical progress and pathogenic findings of MDA5-DM.

Therapeutic plasma exchange for steroid refractory idiopathic inflammatory myopathies with interstitial lung disease

BACKGROUND

Idiopathic inflammatory myopathies (IIMs) encompass many rheumatologic diseases characterized by inflammatory muscle disease, typically unified by proximal muscle weakness. A subset of patients with IIM present with interstitial lung disease (ILD) with identifiable antibodies such as in anti-synthetase syndrome (AS) with antibodies to aminoacyl-tRNA synthetases, and clinically amyopathic dermatomyositis (CADM) with anti-melanoma differentiation-associated protein 5 (MDA5). Recent case reports demonstrate response to therapeutic plasma exchange (TPE) or column filtration plasmapheresis in IIM with ILD resistant to medical management. We present our experience with eight patients with IIM with ILD undergoing TPE at a large US-based hospital system.

PATIENT CHARACTERISTICS

Eight patients with IIM with ILD were treated with TPE over the last 10 years. The therapy consisted of 5-7 one plasma volume exchanges every other day to daily. Seven of eight patients had identifiable antibodies.

RESULTS

Following completion of TPE, seven of eight demonstrated improvement in pulmonary function despite lack of improvement of pulmonary function with standard therapy.

CONCLUSION

In antibody-mediated, treatment refractory IIM with ILD, TPE may be a viable intervention. This is a disease for which the role of apheresis is evolving.

CLINICAL TRIAL REGISTRATION

Not application.

Lung transplantation for anti-MDA5-positive dermatomyositis-associated rapid progressive interstitial lung disease: report of two cases and review of the literature

Lung transplantation is an ultimate lifesaving treatment for many patients with end-stage lung disease, whereas whether it is an optional intervention for the anti-melanoma differentiation-associated gene 5 (anti-MDA5)-positive dermatomyositis (DM)-associated rapid progressive interstitial lung disease (RP-ILD) remain controversial. We report two patients diagnosed with anti-MDA5-positive DM-associated RP-ILD, who were both bridging to lung transplant with extracorporeal membrane oxygenation (ECMO) after failing to respond to extensive immunosuppressants. The first patient received full rehabilitation, but the second patient died of DM flare at the early-stage post-lung transplantation. Most of the clinical information was parallel in these two patients except the anti-MDA5 antibody level, which gradually decreased and became negative in the first patient but always hovering in high titers in the second patient, although both of the two patients received standard immunosuppressive regimen for prevention of rejection after lung transplantation. A total of 11 patients with anti-MDA5-positive DM-associated RP-ILD who underwent lung transplantation from the literature were identified. Most patients (10/11, 90.1%) were successfully discharged and without DM flare during the follow-up period post-lung transplantation. Nine of them were followed up more than 1 year, and anti-MDA-5 antibody was reported to be negative in four patients, whereas the others were unavailable. Combined with the case series in the literature, our limited experience suggests that lung transplantation is a promising therapeutic option for end-stage patients with anti-MDA5-positive DM-associated RP-ILD, with ECMO as a bridge to lung transplantation, if necessary. However, clearance or a downtrend of anti-MDA5 antibody may be required pre-transplant to avoid DM flare and recurrent RP-ILD post-transplantation.

Dermatomyositis With Anti-MDA5 Antibodies: Bioclinical Features, Pathogenesis and Emerging Therapies

Anti-MDA5 dermatomyositis is a rare systemic autoimmune disease, historically described in Japanese patients with clinically amyopathic dermatomyositis and life-threatening rapidly progressive interstitial lung disease. Subsequently, the complete clinical spectrum of the disease was enriched by skin, articular and vascular manifestations. Depending on the predominance of these symptoms, three distinct clinical phenotypes with different prognosis are now defined. To date, the only known molecular component shared by the three entities are specific antibodies targeting MDA5, a cytosolic protein essential for antiviral host immune responses. Several biological tools have emerged to detect these antibodies, with drawbacks and limitations for each of them. However, the identification of this highly specific serological marker of the disease raises the question of its role in the pathogenesis. Although current knowledge on the pathogenic mechanisms that take place in the disease are still in their enfancy, several lines of evidence support a central role of interferon-mediated vasculopathy in the development of skin and lung lesions, as well as a possible pathogenic involvement of anti-MDA5 antibodies. Here, we review the clinical and biological evidences in favor of these hypothesis, and we discuss the contribution of emerging therapies that shed some light on the pathogenesis of the disease.

Spontaneous Pneumomediastinum due to Anti-Melanoma Differentiation-Associated Protein 5 Requiring a Bilateral Lung Transplant

Anti-melanoma differentiation-associated protein 5 (anti-MDA5) is a subset of dermatomyositis associated with respiratory complications, in which rapidly progressive interstitial lung disease (RPILD) is commonly cited, and spontaneous pneumomediastinum (SPM) is a rare complication. In medical literature, aggressive immunosuppressive therapy has been the mainstay of anti-MDA5-associated SPM management. Here, we report the first MDA5 case with SPM which was successfully treated with a double-lung transplant. We present a 48-year-old male who presented with multiple constitutional symptoms such as fevers, weight loss, malaise, and arthralgias, in association with erythroderma over the ears and fingers. Imaging of the chest demonstrated peripheral airspace disease, and myositis-specific serology returned positive for anti-Jo1 (medium-positive), anti-Ro52 (high-positive), and anti-MDA5 (weak-positive) autoantibodies. Therefore, the patient was begun on immunosuppressive therapy as the leading diagnosis included autoimmune myositis, possibly antisynthetase syndrome with interstitial lung disease (ILD). A year later, the patient presented with progressive shortness of breath, widespread macular erythematous facial rash, and new erythematous ulcerations over the fingertips. Imaging demonstrated a new SPM at this juncture. As the patient's respiratory status continued to decline despite the use of immunosuppressive agents, a double-lung transplant was performed. Therefore, we propose that lung transplantation should be considered early in MDA5-SPM.

Pharmacologic Treatment of Anti-MDA5 Rapidly Progressive Interstitial Lung Disease

Purpose of the Review

Idiopathic inflammatory myopathies are a heterogeneous group of autoimmune disorders. The presence of different autoantibodies allows clinicians to define distinct phenotypes. Antibodies against the melanoma differentiation-associated protein 5 gene, also called anti-MDA5 antibodies, are associated with a characteristic phenotype, the clinically amyopathic dermatomyositis with rapidly progressive interstitial lung disease. This review aims to analyze the different pharmacological options for the treatment of rapidly progressive interstitial lung disease in patients with anti-MDA5 antibodies.

Recent Findings

Evidence-based therapeutic recommendations suggest that the best initial approach to treat these patients is an early combination of immunosuppressive drugs including either glucocorticoids and calcineurin inhibitors or a triple therapy adding intravenous cyclophosphamide. Tofacitinib, a Janus kinase inhibitor, could be useful according to recent reports. High ferritin plasma levels, generalized worsening of pulmonary infiltrates, and ground-glass opacities should be considered predictive factors of a bad outcome. In this scenario, clinicians should consider rescue therapies such as therapeutic plasma exchange, polymyxin-B hemoperfusion, veno-venous extracorporeal membrane oxygenation, or even lung transplantation.

Summary

Combined immunosuppressive treatment should be considered the first-line therapy for patients with anti-MDA5 rapidly progressive interstitial lung disease. Aggressive rescue therapies may be useful in refractory patients.

Slowly progressive interstitial lung disease preceding typical dermatomyositis symptoms in anti-melanoma differentiation-associated gene 5 antibody-positive clinically amyopathic dermatomyositis

A 73-year-old woman who visited our hospital complaining of dry cough for three months was refractory to antimicrobial therapy. Chest computed tomography revealed subpleural consolidation. Specimens obtained from surgical lung biopsy revealed subpleural perilobular airspace organization and fibrosis. After the biopsy, mechanic's hand and Gottron's papules appeared, and anti-melanoma differentiation-associated gene 5 (MDA5) antibody was found to be positive. Subsequently, anti-MDA5 antibody measured in cryopreserved serum from her first admission proved to be positive. It is difficult to suspect the presence of anti-MDA-5 antibody in patients with interstitial lung disease without typical dermatomyositis symptoms or slow disease progression.