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Ann Rheum Dis 72:728-735 doi:10.1136/annrheumdis-2012-201381
  • Clinical and epidemiological research
  • Extended report

Prevalence of interferon type I signature in CD14 monocytes of patients with Sjögren's syndrome and association with disease activity and BAFF gene expression

Open Access
  1. Marjan A Versnel1
  1. 1Department of Immunology, Erasmus MC, Rotterdam, The Netherlands
  2. 2Department of Gastroenterology, LUMS, Leiden, The Netherlands
  1. Correspondence to Zana Brkic, Department of Immunology, Erasmus MC, Dr Molewaterplein 50, 3015 GE Rotterdam, The Netherlands; z.brkic{at}erasmusmc.nl
  • Received 19 January 2012
  • Accepted 19 May 2012
  • Published Online First 26 June 2012

Abstract

Objective To determine the prevalence of upregulation of interferon (IFN) type I inducible genes, the so called ‘IFN type I signature’, in CD14 monocytes in 69 patients with primary Sjögren's syndrome (pSS) and 44 healthy controls (HC) and correlate it with disease manifestations and expression of B cell activating factor (BAFF).

Methods 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.

Results 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.

Conclusions The monocyte IFN type I signature identifies a subgroup of patients with 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.

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