Lung involvement associated with anti-NXP2 autoantibodies in inflammatory myopathies: a French monocenter series

Background Inflammatory myopathies (IM) are characterized by muscular inflammation that can be associated with systemic disorders including lung. Anti-NXP2 antibody (Ab) is a rare myositis-specific antibody and its association with pulmonary involvement is still unknown. In this study, we investigated the characteristics of lung disease in patients with IM associated with anti-NXP2 Ab. Methods Adult patients with confirmed IM and positive anti-NXP2 antibodies were recruited in our University departments (Assistance Publique- Hopitaux de Marseille, France), between 2015 and 2019 to perform a retrospective study. Results Seven patients were identified. Mean age was 55 +/- 13 years, with a predominance of females (71%). Two patients (29%) had respiratory symptoms. CT-scan shows abnormalities in three patients (organizing pneumonia, nonspecific interstitial pneumonia, and bilateral pleural effusion). An altered diffusing capacity for carbon monoxide was found in four patients. Conclusion We observed that subclinical lung involvement is not rare in patients with IM associated with positive anti-NXP2 Ab, with various radiological patterns and a significant lung function defect. Such data deserve to be known by the pulmonologist in order to perform a complete lung screening in all patients with positive anti-NXP2 antibody and to detect earlier a concomitant lung impairment.