The significance of interferon-inducible protein-16 and anti-interferon-inducible protein-16 antibodies in rheumatoid arthritis: Relation to pulmonary disease and serological markers

Abstract

AimThe aim of the study was to detect the presence of interferon-inducible protein-16 (IFI16) as well as anti-IFI16 antibodies in the serum and synovial fluid of patients with rheumatoid arthritis (RA) and to evaluate the relation to pulmonary interstitial lung disease (ILD) patterns, disease activity, joints erosions, and serological markers.Patients and methodsThis study involved two groups: 82 adult patients with established RA participated as a study group, whereas 30 patients with knee osteoarthritis also joined as a control group. IFI16 and anti-IFI16 immunoglobulin G were assessed by enzyme-linked immunosorbent assay in serum of all patients and controls, whereas both markers were assessed in synovial fluid withdrawn from 36 patients with RA patients and 14 patients of controls. High-resolution computed tomography was used for assessment of pulmonary involvement.ResultsSerum and synovial levels of IFI16 protein and anti-IFI16 antibodies were significantly elevated in patients with RA than controls (P < 0.001 and P = 0.02, respectively). Patients with RA with pulmonary involvement showed higher serum level of IFI16 protein as well as anti-IFI16 antibody titer than other patients (P < 0.001 and P = 0.005, respectively). No significant differences were reported between different patterns of RA-ILD regarding serum level of IFI16 protein or anti-IFI16 antibody titer. The latter markers were positively correlated with anti-cyclic citrullinated peptide antibody titer (P < 0.001 and P = 0.037, respectively).ConclusionSerum IFI16 and anti-IFI16 antibodies could be used as valuable indicators of RA-related pulmonary ILD but larger studies are needed to confirm it.