Progression to rheumatoid arthritis in early inflammatory arthritis is associated with low IL-7 serum levels
- Vincent Goëb1,2,
- Philippe Aegerter3,4,
- Rekha Parmar1,
- Patrice Fardellone2,
- Oliver Vittecoq5,6,
- Philip G Conaghan1,
- Paul Emery1,
- Xavier Le Loët5,6,
- Frédérique Ponchel1
- 1Division of Musculoskeletal Disease, Leeds Institute of Molecular Medicine, University of Leeds & NIHR Leeds Musculoskeletal Biomedical Research Unit, Leeds, UK
- 2Department of Rheumatology, Amiens University Hospital, Amiens, France
- 3Département de santé publique, AP-HP, Hôpital Ambroise Paré, Boulogne-Billancourt, France
- 4Université Versailles St-Quentin, UPRES EA 2506, Paris, France
- 5Department of Rheumatology, Rouen University Hospital, Rouen, France
- 6Inserm U905, Rouen University, Rouen, France
- Correspondence to Professor Paul Emery, Leeds Musculoskeletal Biomedical Research Unit, Chapel Allerton Hospital, Leeds LS7 4SA, UK;
- Accepted 18 September 2012
- Published Online First 19 October 2012
Objective Early diagnosis of rheumatoid arthritis (RA) remains a challenge. Interleukin (IL)-7 is a pleiotropic cytokine that plays a central role in the development and maintenance of T-cells and has been associated with T-cell dysfunction in RA. Serum levels of IL-7 are reduced in both early and established disease. The aim of this study was to determine whether serum IL-7 can identify patients with very early inflammatory joint symptoms who will progress to RA, and to examine whether IL-7 levels predict disease persistence and radiographic progression.
Methods Patients with inflammatory joint symptoms <6 months followed over 5 years for progression to RA and 80 healthy controls were studied. Baseline IL-7 levels were measured by ELISA.
Results Of 250 patients, 108 developed RA (ACR 1987- criteria). IL-7 at inclusion was reduced significantly in RA compared with non-RA patients (p=0.009). IL-7 was categorised using the lower limit of the healthy control distribution (10 pg/ml). In multivariate analysis, independent predictors of RA development were: antibodies against citrullinated peptides (ACPA) positivity (p=0.001), IL-7<10 pg/ml (p=0.003) and swollen joint count (p=0.050). In the ACPA-negative subgroup (n=199), the only predictors were: DAS-44 (p=0.001), IL-7<10 pg/ml (p=0.010) and radiographic erosions (p=0.050). At 1-year follow-up, remission (DAS<1.6) was only predicted by ACPA negativity (p=0.019) and IL-7>17 pg/ml at recruitment (p=0.013).
Conclusion These data demonstrate that low IL-7 levels in patients with recent onset of symptoms may have value as a diagnostic biomarker predicting the progression to RA, particularly in ACPA-negative disease, as well as being related to RA progression.