| Abstract [eng] |
Idiopathic inflammatory myopathies are rare and heterogeneous autoimmune diseases characterized by chronic inflammation and progressive muscle weakness. In addition to muscular involvement, these diseases frequently affect other organ systems, including the skin, lungs, and joints. This heterogeneity contributes to the significant clinical complexity of the disease. Idiopathic inflammatory myopathies present challenges in diagnosis, classification, and management, and there is a need for improved understanding of the disease subtypes. This thesis aimed to evaluate the role of myositis-specific autoantibodies in the diagnosis of idiopathic inflammatory myopathies and to determine their value in identifying distinct disease subtypes. To achieve this, the history and classification of idiopathic inflammatory myopathies were examined. The role of myositis-specific autoantibodies in current diagnostic approaches and their association with distinct clinical phenotypes were reviewed. A literature-based approach was used to analyse current studies on established myositis-specific autoantibodies and their clinical associations. Relevant literature was identified through database searches and critical evaluations of the research findings. The results demonstrate that individual myositis-specific autoantibodies are strongly associated with specific clinical features and disease outcomes. Anti-MDA5 is associated with clinically amyopathic dermatomyositis and rapidly progressive interstitial lung disease, representing a severe disease phenotype. Anti-NXP2 antibodies are associated with calcinosis in juvenile patients and malignancy in adult patients. In contrast, anti-Mi2 is highly specific to dermatomyositis and is associated with a favourable prognosis and good response to treatment. Anti-TIF1-γ is associated with malignancy in adult patients, while presenting different clinical features in juvenile patients. Anti-Jo-1 is the most common myositis-specific autoantibody present in antisynthetase syndrome. Next to anti-Jo-1 many other myositis-specific autoantibodies exist for antisynthetase syndrome, which associate with interstitial lung disease, but are a lot less common. Immune-mediated necrotizing myopathy is another subtype of idiopathic inflammatory myopathies that presents with two antibodies: anti-SRP and anti-HMGCR. Despite these diagnostic advances, some limitations remain. Myositis-specific autoantibodies are not entirely disease-specific. Variability in the laboratory testing methods can affect accuracy. A significant proportion of patients remain seronegative, suggesting that additional autoantibodies must be identified. Clinical presentation can vary within subgroups, and findings across studies are not always consistent. In conclusion, myositis-specific autoantibodies play a central role in improving the understanding, diagnosis, classification, and management of idiopathic inflammatory myopathies. However, their interpretation requires integration with clinical findings, and further research is needed to refine the classification systems and improve patient management. |
