Statistics from Altmetric.com
We read with great interest the article by Sabbagh et al demonstrating that anti-Ro52 autoantibodies were connected with the development of interstitial lung disease (ILD) in patients with juvenile myositis.1 Anti-Ro52 has been found in a variety of connective tissue diseases (CTDs) and drawn considerable attention from rheumatologists in recent years. Besides myositis, these autoantibodies have also been reported to be related to ILD in several other CTDs, but with great discrepancy across the studies.2 In addition, it remains unclear how the incidence of ILD differs in the presence of anti-Ro52 alone or in combination with anti-Ro60 (Sjogren's syndrome related antigen A), one of the most associated antibodies that may determine anti-Ro52 epitope mapping.3
To explore the clinical features of anti-Ro52 and its relationship with anti-Ro60, we retrieved the medical records of 1979 patients tested positive for anti-Ro52 and hospitalised between January 2016 and September 2017 in the Drum Tower Hospital. Both anti-Ro52 and anti-Ro60 were routinely measured using an immunoblotting method (EUROLINE, EUROIMMUN AG, Germany). The majority of our cases were female (1457, 73.6%) and the average age was 53.0±16.8 years old. Totally 1321 (66.8%) patients were diagnosed as having CTDs and 658 (33.2%) diagnosed as non-CTDs.
Distribution of ILD in patients with various diseases is summarised in table 1. In this cohort, ILD occurred in 37.1% of anti-Ro52 positive CTD patients and 10.9% of anti-Ro52 positive non-CTD patients. Among CTDs, idiopathic inflammatory myopathy (IIM) was the most often seen underlying disease (85.4%), followed by undifferentiated connective tissue disease (UCTD), systemic sclerosis, rheumatoid arthritis (RA) and primary Sjögren’s syndrome (pSS). As for systemic lupus erythematosus, only 6.5% anti-Ro52 positive patients presented ILD, consistent with its low incidence in this prototypic autoimmune disease.4
There was no discussion of the difference between anti-Ro52 single-positive and anti-Ro52/Ro60 double-positive in Sabbagh et al’s article.1 Previously, it has been implied that the expressions of these two types of autoantibodies were related to different CTDs,5 and those with isolated anti-Ro52 were more prone to IIM and inflammatory rheumatism.6 Our data showed that the distribution of ILD was also varied between the two groups. The incidence of ILD was increased in both CTD and non-CTD patients with single-positive anti-Ro52 (OR 4.94, p<0.0001 and OR 3.41, p<0.05 by χ2 and Baptista-Pike analysis). However, compared with those having both anti-Ro52 and anti-Ro60, patients with isolated anti-Ro52 were more likely to develop ILD in RA (OR 6.11), pSS (OR 4.50), polymyositis (PM) (OR 10.00) and UCTD (OR 3.71), but not other CTDs including dermatomyositis (table 1).
In conclusion, our data support that ILD is associated with anti-Ro52, yet the incidence is quite different among various CTDs. For patients with RA, pSS, PM or UCTD, the positivity of anti-Ro52 without anti-Ro60 may indicate the occurrence of ILD.
Contributors SW, XT and LW collected data. SW analysed results and drafted the manuscript. L-jLU and XF designed the study. XF supervised the project and edited the manuscript. All authors made substantial intellectual contributions to conception of the work, the interpretation of data and approval of the final manuscript.
Funding This study was supported by grants from National Key Research and Development Program of China (2017YFC0909003) and National Natural Science Foundation of China (81771745).
Competing interests None declared.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; internally peer reviewed.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.