Stockfelt, Marit; Lundell, Anna-Carin; Hetland, Merete Lund; Ostergaard, Mikkel; Uhlig, Till; Heiberg, Marte Schrumpf; Haavardsholm, Espen A.; Nurmohamed, Michael T.; Lampa, Jon; Nordström, Dan; Petersen, Kim Horslev; Gudbjornsson, Bjorn; Grondal, Gerdur; Aldridge, Jonathan; Andersson, Kerstin; Blennow, Kaj; Zetterberg, Henrik; van Vollenhoven, Ronald; Rudin, Anna
(2021)
Background The type I interferon (IFN) gene signature is present in a subgroup of patients with early rheumatoid arthritis (RA). Protein levels of IFN alpha have not been measured in RA and it is unknown whether they associate with clinical characteristics or treatment effect. Methods Patients with early untreated RA (n = 347) were randomized to methotrexate combined with prednisone, certolizumab-pegol, abatacept, or tocilizumab. Plasma IFN alpha protein levels were determined by single molecular array (Simoa) before and 24 weeks after treatment initiation and were related to demographic and clinical factors including clinical disease activity index, disease activity score in 28 joints, swollen and tender joint counts, and patient global assessment. Results IFN alpha protein positivity was found in 26% of the patients, and of these, 92% were double-positive for rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA). IFN alpha protein levels were reduced 24 weeks after treatment initiation, and the absolute change was similar irrespective of treatment. IFN alpha protein positivity was associated neither with disease activity nor with achievement of CDAI remission 24 weeks after randomization. Conclusion IFN alpha protein positivity is present in a subgroup of patients with early RA and associates with double-positivity for autoantibodies but not with disease activity. Pre-treatment IFN alpha positivity did not predict remission in any of the treatment arms, suggesting that the IFN alpha system is distinct from the pathways of TNF, IL-6, and T-cell activation in early RA. A spin-off study of the NORD-STAR randomized clinical trial, NCT01491815 (ClinicalTrials), registered 12/08/2011, .