Predictive Value of Serum sIL‐2R Levels and Th17/Treg Immune Balance for Disease Progression in Patients With Rheumatoid Arthritis‐Associated Interstitial Lung Disease

ABSTRACT Background This article analyzed the relationship between serum sIL‐2R levels and Th17/Treg immune balance in patients with rheumatoid arthritis‐associated interstitial lung disease (RA‐ILD) and their prognostic value. Methods RA patients ( n = 311) were retrospectively selected for research and then allocated to the RA and RA‐ILD groups. Baseline data and 3‐year follow‐up records of all patients were attained to assess disease progression. Serum sIL‐2R levels were examined with ELISA, and Th17 and Treg cell clusters were tested with flow cytometry, followed by the calculation of the Th17/Treg ratio. The correlation of serum sIL‐2R with Th17/Treg and related cytokines (IL‐17, IL‐6, IL‐10, and TGF‐β1) in RA‐ILD patients were analyzed with Spearman's analysis. ROC curves were plotted for analyzing the performance of serum sIL‐2R levels and the Th17/Treg ratio for predicting disease progression in RA‐ILD patients. A multivariate Cox regression model was developed to screen independent risk factors for disease progression in RA‐ILD patients. Results RA‐ILD patients had elevated serum levels of sIL‐2R, Th17 cells, IL‐17, and IL‐6 and an increased ratio of Th17/Treg, accompanied by a decreased Treg cell population and IL‐10 and TGF‐β1 levels. Serum sIL‐2R levels were correlated positively with IL‐17 levels and the Th17/Treg ratio in RA‐ILD patients and negatively with IL‐10 levels. DAS28 scores, serum sIL‐2R levels, and an elevated Th17/Treg ratio were independent risk factors for disease progression in RA‐ILD patients, and increased FEV1 and FEV1/FVC were protective factors. Conclusion Serum sIL‐2R levels in conjunction with Th17/Treg immune balance can assist in predicting 3‐year disease progression in RA‐ILD patients.