title: Increased serum type I interferon activity in early systemic sclerosis patients is associated with antibodies against Sjögren's syndrome antigens and nuclear ribonucleoprotein antigens.
abstract: OBJECTIVE
  To study serum type I interferon (IFN) activity in patients with early systemic sclerosis (SSc).
  
  
  METHODS
  Serum type I IFN activity was measured in 33 consecutive patients with SSc and a disease duration of < 2 years and in 13 healthy individuals by calculating a type I IFN score according to the induction of six IFN-α regulated genes in a reporter cell line.
  
  
  RESULTS
  Twenty-seven per cent of the SSc patients had an increased type I IFN score compared to none of the healthy individuals (p < 0.05). The clinical SSc phenotype associated with high serum type I IFN activity did not differ from patients with low serum type I IFN activity regarding the presence of skin or lung fibrosis, pulmonary hypertension, or digital complications. Patients with high serum type I IFN activity were younger (p < 0.01) and had a lower frequency of cardiac involvement (p = 0.053), lower leucocyte count (p < 0.001), higher immunoglobulin (Ig)G levels (p < 0.05), and a higher amount of antibodies against extractable nuclear antigens (p < 0.01) than patients with low serum type I IFN activity. The presence of antibodies against topoisomerase I, Sjögren's syndrome antigen, and nuclear ribonucleoprotein antigens was associated with higher type I IFN activity (p < 0.05 for all comparisons).
  
  
  CONCLUSIONS
  Our study indicates that increased serum type I IFN activity in early SSc patients is associated with an antibody and laboratory profile that may reflect a subclinical overlap of SSc with other type I IFN-driven connective tissue diseases (CTDs).
authors: Section of Rheumatology, Department of Clinical Sciences, Lund University/Skåne University Hospital, Lund, Sweden. dirk.wuttge@med.lu.se
authors: D M
authors: DM
authors: Wuttge
authors: C
authors: C
authors: Lood
authors: E
authors: E
authors: Tufvesson
authors: A
authors: A
authors: Scheja
authors: L
authors: L
authors: Truedsson
authors: A A
authors: AA
authors: Bengtsson
authors: R
authors: R
authors: Hesselstrand
mesh_terms: D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007370:Interferon Type I / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012261:Ribonucleoproteins / Q000276:immunology; D012595:Scleroderma, Systemic / Q000097:blood / Q000276:immunology*; D012859:Sjogren's Syndrome / Q000276:immunology
chemical_list: D001323:Autoantibodies; D007370:Interferon Type I; D012261:Ribonucleoproteins