Background The role of specific cytokines in lupus arthritis has not been elucidated¹. This is in stark contrast to rheumatoid arthritis (RA) where an abundance of research has culminated in an advancing era of novel biologic drugs.

Objectives To analyse the cytokine profile in SLE patients with erosive, non-erosive arthritis and arthralgia as classified by ultrasound (US).

Methods 50 SLE patients, and 40 RA patients had an US scan of their hand as per standardised protocols^2-3. US scores per patient were expressed per joint and as a total ‘ultrasound activity’ score, (sum of Power Doppler (PD) and Grey Scale Synovial Hypertrophy scores in all joints) and a total erosion score. SLE disease activity was assessed (BILAG and SELENA SLEDAI). Plasma levels of IL-6, TNF-alpha and BLyS were measured using sandwich ELISA kits (Quantikine® kits, R & D).

Results On the basis of the ultrasound results the SLE patients were divided into three groups, those with erosive arthritis (n = 24), those with non-erosive arthritis (n = 14) and those with a normal ultrasound scan (n = 12). CRP and IL-6 levels between the erosive lupus group and the RA group were not significantly different (p = 0.3 and p = 0.2 respectively).

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Conclusions This is the first study to examine levels of specific cytokines in a cohort of SLE patients stratified in terms of joint disease by ultrasound where the most significant finding is that IL-6 levels correlated with both clinical and ultrasound measures of arthritis disease activity. There is preliminary evidence that IL-6 blockade may be a potential treatment for SLE⁴ and if arthritis specific outcome measures were included in future clinical trials more robust evidence could be generated.

References

1. Jacob N & Stohl W. Cytokine disturbances in Systemic Lupus Erythematosus. Arthritis Research & Therapy 2011; 13 (4): 244

2. Wakefield RJ et al. Musculoskeletal ultrasound including definitions for ultrasonographic pathology. J Rheum 2005;32(12):2485-87.

3. Szkudlarek M et al. Interobserver agreement in ultrasonography of the finger and toe joints in rheumatoid arthritis. A & R 2003;48(4):955-62.

4. Illei G et al. Tocilizumab in systemic lupus erythematosus: data on safety...... A & R 2010;62(2):542-52.

Disclosure of Interest None Declared