Epitope spreading of anti-RNA polymerase III antibodies may serve as a potential biomarker for disease activity and progression in systemic sclerosis, particularly in patients with diffuse cutaneous involvement, according to a recent study.
In the study, published in Arthritis & Rheumatology, researchers analyzed the epitope spreading of anti-RNA polymerase (RNAP) III antibodies in patients with systemic sclerosis (SSc), focusing on clinical correlations and disease manifestations. The study examined 34 patients with SSc positive for anti-RNAP III antibodies (ARAs), with 27 (79%) diagnosed with diffuse cutaneous systemic sclerosis (dcSSc) and 7 (21%) with limited cutaneous systemic sclerosis (lcSSc).
The median modified Rodnan skin score (mRSS) was 16 (interquartile range [IQR] = 12–24) in patients with dcSSc and 8 (IQR = 2–13) in patients with lcSSc, with a P value of less than .01, indicating a statistically significant difference in skin involvement between the two groups.
Interstitial lung disease (ILD) was observed in 68% (n = 23) patients, with a significantly higher prevalence in patients who had dcSSc (78%) compared with patients who had lcSSc (29%), as indicated by a P value of .02. Pulmonary function, measured by the percentage of predicted forced vital capacity (FVC), had a median value of 89% for the cohort, with 89% in patients with dcSSc and 106% in patients with lcSSc. The median percentage of predicted lung diffusing capacity for carbon monoxide (DLCO) was 96% across all patients.
Heatmap analysis demonstrated correlations between RNAP III autoantibody indices and clinical markers such as skin score, pulmonary function, and ILD markers. Autoantibodies targeting different RNAP III subunits were associated with declining lung function, as reflected in reduced FVC and DLCO values.
The study concluded that epitope spreading of ARAs across RNAP III subunits may serve as a biomarker of disease activity and progression in SSc.
The researchers reported no conflicts of interest.