# Pulmonary Involvement in Patients with Positive Myositis Antibodies in Rheumatology: A Retrospective Monocentric Analysis

## TL;DR

This study examines how myositis antibodies relate to lung disease in patients with inflammatory muscle disorders, finding that certain antibodies are strongly linked to lung involvement.

## Contribution

The study provides new insights into the clinical relevance of specific myositis antibodies in predicting interstitial lung disease in idiopathic inflammatory myopathy.

## Key findings

- Patients with IIM had significantly higher rates of interstitial lung disease compared to other groups.
- PL12- and MDA5-positive patients showed the highest proportions of lung involvement.
- Myositis antibodies are more relevant for lung risk assessment in IIM than in other rheumatic diseases.

## Abstract

Background: Pulmonary involvement is the most common prognosis-related organ involvement in idiopathic inflammatory myopathy (IIM). Owing to the large number of antibodies, the evidence for lung involvement and rare antibodies is limited. In everyday clinical practice, the interpretation of positive myositis antibodies represents a challenge. Methods: This study is a retrospective monocentric analysis. The data collection regarding positive myositis antibodies and possible pulmonary involvement was carried out from July 2019 to May 2022. Data analysis revealed positive results for one of the following antibodies: EJ, PL7, OJ, PL12, Mi-2α, TIF1γ, MDA5, SAE, NXP2, SRP, Ku, PM-Scl100 and PM-Scl75. In our analysis, patients with IIM, patients with inflammatory rheumatic disease other than IIM and patients without inflammatory rheumatic disease are described. The results of high-resolution computed tomography (HRCT), pulmonary function tests, echocardiographic examinations and their associated clinical findings are examined. Results: In the entire cohort, 209 patients with positive myositis antibodies were detected. In total, 22 (10.5%) patients had interstitial lung disease (ILD) patterns on HRCT. In the subgroup of patients with IIM, a significantly higher proportion of patients with lung involvement (n = 13, 35.1%) was found than in the group with other inflammatory rheumatic diseases (IRDs) (n = 6, 6.7%) or in the group without IRDs (n = 3, 3.7%). When the antibody groups were considered, the PL12-positive patients had the largest proportion of ILD (42%), followed by the MDA5-positive patients (40%). Conclusions: In patients with IIM, myositis antibodies are highly relevant for assessing the risk of lung involvement. In groups with other IRD or without IRD, antibody detection does not represent this high relevance for lung involvement. A differentiated assessment of the various MSAs or MAAs detected, as well as clinical parameters, allows for further important risk assessment for prognosis-relevant lung involvement.