Prevalence of interferon type I signature in CD14 monocytes of patients with Sjogrens syndrome and association with disease activity and BAFF gene expression
Annals of Rheumatic Diseases, 07/17/2012

Brkic Z et al. – The monocyte interferon (IFN) type I signature identifies a subgroup of patients with primary Sjögren's syndrome (pSS) with a higher clinical disease activity together with higher BAFF mRNA expression. Such patients might benefit from treatment blocking IFN type I production or activity.

• Expression of IFI44L, IFI44, IFIT3, LY6E and MX1 was measured using real time quantitative PCR in monocytes.
• Expression values were used to calculate IFN type I scores for each subject.
• pSS patients positive for the IFN type I signature (IFN score≥10) and patients negative for the signature (IFN score<10) were then compared for clinical disease manifestations and BAFF expression.
• A bioassay using a monocytic cell line was performed to study whether BAFF mRNA expression was inducible by IFN type I activity in serum of patients with pSS.

• An IFN type I signature was present in 55% of patients with pSS compared with 4.5% of HC.
• Patients with the IFN type I signature showed:
• (a) higher EULAR Sjögren's Syndrome Disease Activity Index scores; higher anti–Ro52, anti–Ro60 and anti–La autoantibodies; higher rheumatoid factor; higher serum IgG; lower C3, lower absolute lymphocyte and neutrophil counts;
• (b)higher BAFF gene expression in monocytes.
• In addition, serum of signature–positive patients induced BAFF gene expression in monocytes.