Roles of biomarkers in anti‐MDA5‐positive dermatomyositis, associated interstitial lung disease, and rapidly progressive interstitial lung disease

BACKGROUND: Anti‐melanoma differentiation‐associated gene 5 (MDA5)‐positive dermatomyositis (MDA5(+)DM) is significantly associated with interstitial lung disease (ILD), especially rapidly progressive ILD (RPILD) due to poor prognosis, resulting in high mortality rates. However, the pathogenic mechanism of MDA5(+)DM‐RPILD is unclear. Although some MDA5(+)DM patients have a chronic course of ILD, many do not develop RPILD. Therefore, the related biomarkers for the early diagnosis, disease activity monitoring, and prediction of the outcome of RPILD in MDA5(+)DM patients should be identified. Blood‐based biomarkers are minimally invasive and can be easily detected. METHODS: Recent relative studies related to blood biomarkers in PubMed were reviewed. RESULTS: An increasing number of studies have demonstrated that dysregulated expression of blood biomarkers related to ILD such as ferritin, Krebs von den Lungen‐6 (KL‐6), surfactant protein‐D (SP‐D), and cytokines, and some tumor markers in MDA5(+)DM may provide information in disease presence, activity, treatment response, and prognosis. These studies have highlighted the great potentials of blood biomarker values for MDA5(+)DM‐ILD and MDA5(+)DM‐RPILD. This review provides an overview of recent studies related to blood biomarkers, besides highlighted protein biomarkers, including antibody (anti‐MDA5 IgG subclasses and anti‐Ro52 antibody), genetic (exosomal microRNAs and neutrophil extracellular traps related to cell‐free DNA), and immune cellular biomarkers in MDA5(+)DM, MDA5(+)DM‐ILD, and MDA5(+)DM‐RPILD patients, hopefully elucidating the pathogenesis of MDA5(+)DM‐ILD and providing information on the early diagnosis, disease activity monitoring, and prediction of the outcome of the ILD, especially RPILD. CONCLUSIONS: Therefore, this review may provide insight to guide treatment decisions for MDA5(+)DM‐RPILD patients and improve outcomes.