Role of Interleukin-17 in Predicting Activity of Rheumatoid Arthritis and Systemic Lupus Erythematosus.

Background: Although high serum levels of interleukin (IL)-17 and its producing cells have been found in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) in earlier research, it is still unclear how these findings relate to disease activity.

Objectives: This study examines the link between serum levels of IL-17 and the activity of both RA and SLE.

Design: This pilot case-control study included 100 patients with RA, 100 with SLE, and 100 healthy controls.

Methods: The Disease Activity Score-28 (DAS28) scores assessed the activity of RA, whereas the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) scores assessed SLE activity. All participants' data were compared and correlated.

Results: Serum levels of IL-17 were significantly higher in RA and SLE patients compared with the controls (P < .001) and showed significantly positive correlations (P < .001) with rheumatoid factor titer, anti-cyclic citrullinated peptide (anti-CCP) and DAS28 score among the RA patients. Although among SLE patients, they were significantly positively correlated (P < .001) with anti-double-stranded DNA (anti-ds DNA) levels and the SLEDAI-2K scores, the best cut-off value of IL-17 for predicting moderate and high disease activity was > 175 pg/mL among RA patients and > 95 pg/mL among SLE patients.

Conclusions: There is a significant correlation between RA and SLE activity and serum levels of IL-17. This discovery emphasizes IL-17 as a potential therapeutic target.