Abstract
Objectives: Psoriasis is a chronic autoimmune disease involving a complex network of cytokines such as interleukin (IL)-6. We tested the hypothesis that serum IL-6 level is a useful indicator of disease activity and predicts the treatment response to biologics in patients with psoriasis.
Methods: We analyzed 113 psoriasis patients treated with biologics (73 with infliximab [IFX], 24 with adalimumab [ADA], and 16 with ustekinumab [UST]) in our hospital. Disease severity was assessed using the Psoriasis Area and Severity Index (PASI) score, and Disease Activity Score 28 based on C-reactive protein (DAS28-CRP).
Results: Before treatment, serum IL-6 levels significantly correlated with PASI scores in patients with psoriasis vulgaris (r = 0.432, p = 0.001) and with DAS28-CRP in patients with psoriatic arthritis (r = 0.469, p = 0.010). Serum IL-6 levels were significantly decreased by IFX (from 4.8 to 1.5) and ADA (from 2.5 to 1.4) therapy. In psoriatic arthritis, serum IL-6 levels at the endpoint tended to be lower in patients who achieved DAS28-CRP <2.3 (European League Against Rheumatism remission criteria) than in patients who did not.
Conclusion: Serum IL-6 level may be a useful biomarker for assessing disease activity in patients with psoriasis and for predicting responsiveness of joint symptoms to biologic treatment.
Acknowledgments
We express our appreciation to Ms. Nishioka for her technical assistance.
Conflict of interest
A. Morita has served as a consultant and/or paid speaker for and/or participated in clinical trials sponsored by companies that manufacture drugs used for the treatment of psoriasis, including AbbVie (formerly Abbott), Mitsubishi Tanabe, Janssen, Novartis, Eli Lilly, Kyowa-Kirin, LEO Pharma, Maruho and Merck Sharp & Dohme. The other authors have no conflicts of interest.