Current understanding and recent advances in myositis-specific and -associated autoantibodies detected in patients with dermatomyositis

ABSTRACT

Introduction: Dermatomyositis (DM) is characterized by skin lesions, such as heliotrope rash and Gottron’s papules/sign, and skeletal myopathy. Patients with DM often have arthritis, cardiomyopathy, interstitial lung disease (ILD), and concomitant malignancy. Since clinical characteristics, treatment response, and prognosis are highly variable among patients, it is critical to predict future outcomes in DM patients before the initiation of management. Recently, a number of myositis-specific and -associated autoantibodies (MSAs/MAAs) have been identified and well characterized, and commercial assays for their detection have become available.

Areas covered: There is accumulating evidence showing the utility of MSAs/MAAs in diagnosis of DM and in predicting clinical courses and outcomes in patients with DM as convenient biomarkers, i.e. an association of ILD with anti-ARS, anti-MDA5 and anti-SAE; and malignancy with anti-TIF1-γ, anti-NXP2, and anti-SAE in adults. This review describes available assays employed for the detection of MSAs/MAAs and how to integrate autoantibody results into clinical practice of DM patients, mainly adult patients. The relevant literature was searched on PubMed as of 2 November 2019.

Expert opinion: MSAs/MAAs are convenient biomarkers that are useful in personalized medicine and thus should be adopted in routine clinical practice of patients with DM, but in a science-based manner.

KEYWORDS:

• Autoantibody
• biomarker
• dermatomyositis
• interstitial lung disease
• malignancy

Article highlights

• Dermatomyositis (DM) is an idiopathic inflammatory myopathy (IIM) characterized by typical skin lesions, such as heliotrope rash and Gottron’s papules/sign, in combination with skeletal myopathy.

• Interstitial lung disease (ILD) and concomitant malignancy are leading causes for mortality in DM. However, clinical presentation, course, responses to treatment and prognosis are highly variable among patients.

• Myositis specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs) are useful not only for confirming diagnosis but also for predicting clinical phenotypes, responses to treatment, and prognosis in patients with DM. Therefore, information on autoantibodies contributes to better management of patients with DM in routine clinical practice.

• When patients have cutaneous manifestations suspected to have DM, we should evaluate skeletal muscle involvement and perform the anti-nuclear antibody test, followed by identification of individual MSAs/MAAs.

• Screening of concomitant malignancy is essential at the time of DM diagnosis in adult patients, but the extent of screening evaluations should be decided based on malignancy risk in individual patients. In particular, elderly individuals with anti-TIF1-γ antibody have the highest risk for malignancy.

• Evaluation of ILD is also crucial for patients with DM. Patients with anti-MDA5 antibody have a high risk for developing rapidly progressive ILD, while those with anti-ARS antibody often have acute/subacute ILD, which is responsive to immunosuppressive treatment but is prone to recur during the disease course.

• Anti-TIF1-γ and anti-NXP2 antibodies are associated with more extensive myopathy, including dysphagia and severe muscle weakness, which leads to functional disability and resultant impairment of quality of life.

• By combining information on MSAs/MAAs, personalized medicine is feasible based on appropriate disease subsetting and risk prediction.

Declaration of interest

T.G. received speakers' bureau from Medical & biological laboratories. M.K. holds the patent for the anti-MDA5 antibody measurement kit, and speakers' bureau from  Medical & biological laboratories.