Role of anti-CCP in arthritis in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease with multi-organ involvement. Patients with SLE feature a lower tendency to develop erosive arthritis in comparison with rheumatoid arthritis (RA); however, in some arthritis cases it may be difficult to differentiate SLE from RA. Anti-cyclic citrullinated peptide (Anti-CCP) antibodies are highly-specific for RA. The current study evaluated the relationship between anti-CCP and arthritis in SLE patients. In this study, anti-CCP antibodies were tested in 300 patients with SLE. The INOVA Diagnostics QUANTA Lite™ CCP IgG ELISA and the Axis-Shield Diagnostics Diastat™ anti-CCP ELISA test were applied. Patients were divided into two groups: those with and those without arthritis. Patients with chronic arthritis (>6 weeks) had radiography done on the involved joints. Chi square and Fisher’s exact tests were applied to compare the two subsets. Anti-CCP antibodies were detected in 4.7% of all patients (CI: 2.6-7.8). Anti-CCP was positive in 6.4% of patients with arthritis and 2.3% of patients without arthritis (P=0.09). From seven patients with chronic arthritis, one had both positive anti-CCP and erosions. In the studied Iranian SLE patients, anti-CCP levels were higher in patients with arthritis than in those without arthritis. This study did not show any association of anti-CCP with erosion in SLE patients with arthritis. Ethnic and geographical variance may have influenced the results. More studies on chronic arthritis in SLE are needed to confirm this hypothesis.