Adults with rheumatoid arthritis or primary Sjogren’s syndrome plus interstitial lung disease had higher levels of systemic sclerosis–specific antibodies than those without lung disease, based on data from 101 individuals.
Systemic sclerosis (SSc) has been associated with the development of interstitial lung disease (ILD), but the prevalence of SSc autoantibodies in patients with rheumatoid arthritis (RA) and primary Sjogren’s syndrome (SS) has not been explored, wrote Vasilike Koulouri, MD, of Kapodistrian University of Athens, and colleagues.
In a study published in the Journal of Translational Autoimmunity, the researchers reviewed serum data from patients with RA and SS using immunoblot assays to determine the prevalence of SSc-specific and anti-Ro52 autoantibodies, both of which have been associated with ILD in SSc patients.
The study population included 28 RA patients with ILD, 32 RA patients without ILD, 9 primary SS patients with ILD, and 32 primary SS patients with no ILD. The mean age of the RA participants was 63.4 years, 70% were women, and the mean age at RA diagnosis was 50.2 years. The mean age of the primary SS group was 60.3 years, 87.8% were female, and the mean age at diagnosis was 52.7 years.
Overall, SSc-specific antibodies across all titers were detected more frequently in RA patients with ILD compared with those with no ILD, though not statistically significant (42.9% vs. 21.9%, P = .08). However, “This trend was mainly attributed to the statistically significant difference between the two groups at strong titers (25% vs. 3.1%, P = .01),” the researchers wrote. Notably, they added.
No significant differences appeared in the prevalence of SSc-specific or Ro52 autoantibodies between primary SS patients with and without ILD, which might be attributable in part to the increased prevalence of anticentromere antibodies in primary SS, the researchers said.
RA patients who were positive for SSc-specific antibodies at strong titers were significantly more likely to have respiratory abnormalities than those who were negative (87.5% vs. 47.2%, P = .04), but no such differences appeared in primary SS patients.
“Early detection of SSc antibodies could be important in clinical practice as it may mandate further diagnostic (for example, screening for pulmonary hypertension) and therapeutic approaches of these patients,” the researchers wrote in their discussion.
The study findings were limited by several factors, mainly the small sample size, but also the potential for false-positive results on antibody titers, lack of data on the clinical significance of medium autoantibody titers, and the lack of long-term follow-up data, the researchers noted.
However, the results suggest that many seropositive RA patients with evidence of ILD “may evolve to a clinically evident overlap of RA and SSc” that would benefit from targeted treatment, they concluded.
The study was supported by a grant from Novartis AG and by the Molecular Immunology and Clinical Applications Unit, Department of Physiology, School of Medicine, National and Kapodistrian University of Athens. The researchers had no financial conflicts to disclose.