Two sides of the same coin? A review of the similarities and differences between idiopathic pulmonary fibrosis and rheumatoid arthritis-associated interstitial lung disease

Abstract

Rheumatoid arthritis associated interstitial lung disease (RA-ILD) and idiopathic pulmonary fibrosis (IPF) are distinct diseases; however, they share several clinical, radiographic and genetic features. For instance, usual interstitial pneumonia (UIP), which is an ILD pattern required for a diagnosis of IPF, is also the most common ILD pattern in RA-ILD. The presence of UIP in RA-ILD is a poor prognostic sign with outcomes similar to those seen in IPF. The recent finding of a shared genetic susceptibility between IPF and RA-ILD has sparked additional interest in this relationship. This review outlines these similarities and differences in clinical presentation, appearance and outcomes in RA-ILD and IPF.In addition, this review highlights previous research in molecular biomarkers in both conditions, exploring areas of overlap and distinction. This focus on biomarkers in IPF and RA-ILD aims to highlight potential areas of discovery and clues to a potential shared pathobiology through investigation of novel molecular markers or the repurposing of biomarkers from one condition to the other.The drive to better understand RA-ILD by leveraging our knowledge of IPF is underscored by our divergent treatment paradigms for these conditions and the concern for potential harm. As a result of advancing our understanding of the links between IPF and RA-ILD, current strategies for diagnosis, screening and treatment of ILD may fundamentally change in the coming years. Until then, clinicians face difficult clinical questions regarding the co-management of the articular disease and the ILD in RA.

Conflict of interest statement

Conflict of interest: S. Matson has nothing to disclose. Conflict of interest: J. Lee reports grants from NIH, grants and personal fees for advisory board work from Boehringer Ingelheim, personal fees for advisory board work from Galapagos and Celgene, personal fees for consultancy from Eleven P15, outside the submitted work. Conflict of interest: O. Eickelberg reports grants from NHLBI (R01 1R01HL146519), during the conduct of the study; personal fees from Blade Therapeutics, Pieris, Boehringer Ingelheim and Novartis, outside the submitted work.

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