Specific rheumatoid arthritis (RA)-associated anticitrullinated protein/peptide antibodies (ACPA) and rheumatoid factor (RF) isotypes are associated with parenchymal lung abnormalities in patients with early, untreated RA, according to study results published in Rheumatic & Musculoskeletal Disease.
Previous studies reported that lung abnormalities on high-resolution computed tomography (HRCT) are common in individuals at risk of developing RA and in those with early and untreated seropositive RA. The objective of the current study was to determine the association between the ACPA repertoire and lung abnormalities on HRCT in patients with early and untreated RA.
Blood samples were analyzed for the presence of RF and ACPA using either a CCP2 detection kit or an immunochip containing 10 different citrullinated peptides. Statistical analysis determined the association between HRCT findings and antibody repertoire.
The study sample included 106 patients (mean age 57.5 years, 68.9% women) with newly diagnosed and untreated RA, including 68 patients (64.2%) with HRCT airway abnormalities and 58 patients (54.7%) with HRCT parenchymal abnormalities.
The results suggested an association between RA-associated antibodies with parenchymal but not airway abnormalities. Several antibodies were more common in patients with HRCT parenchymal antibodies, compared to patients without those lung findings on imaging, including RF IgA (60.3% vs. 36.2%, P =.014), anti-CCP2 (77.6% vs. 57.4%, P =.027), CCP2 IgG (75.9% vs. 57.4%, P =.045), and any antibody against citrullinated fibrinogen (81.0% vs. 62.5%, P =.033).
The number of different ACPA specificities was significantly associated with parenchymal abnormalities in non-adjusted comparisons but not following adjustment for multiple comparisons.
The study had several limitations, including the relatively small sample size and the lack of long-term follow-up.
“Our findings provide further support for an important pathogenic link between the lung and systemic autoimmunity, contributing to RA development,” concluded the researchers.
Joshua V, Hensvold AH, Reynisdottir G, et al. Association between number and type of different ACPA fine specificities with lung abnormalities in early, untreated rheumatoid arthritis. RMD Open. 2020;6(2):e001278. doi:10.1136/rmdopen-2020-001278