Peripheral biomarkers in rheumatoid arthritis-associated interstitial lung disease: a review of roles and candidates.

Interstitial lung disease associated with rheumatoid arthritis (RA-ILD) is a common extra-articular manifestation of RA that causes increased morbidity and mortality. Effective screening strategies to detect RA-ILD early are lacking. The use of peripheral blood biomarkers represents a promising opportunity to inform and refine screening and monitoring of RA-ILD. Indeed, a number of peripheral biomarkers have been associated with RA-ILD, including autoantibodies, cytokines/chemokines, acute-phase reactants, extracellular matrix proteins, lung epithelial and surfactant proteins, and genetic variants. More recently, composite panels incorporating combinations of peripheral biomarkers have shown utility in identifying RA-ILD. Future studies informing the optimal use of peripheral biomarkers in the screening, prognostication, and monitoring of RA-ILD are needed to validate their clinical performance, define optimal thresholds, and facilitate their integration into routine clinical practice.