Increased serum IL-31 levels in chronic spontaneous urticaria and psoriasis with pruritic symptoms

BACKGROUND: Chronic spontaneous urticaria (CSU) is a common pruritic skin condition, the pathogenesis of which remains unclear. Interleukin-31 (IL-31) is a major pruritogenic cytokine that plays a role in inducing pruritus in various skin diseases. AIM. To 1) compare serum IL-31 levels among CSU patients, psoriasis patients with pruritic symptoms, and healthy subjects, 2) examine the correlations between serum IL-31 levels and disease severity, and 3) compare IL-31 levels in patients with and without CSU-associated auto-antibodies. METHODS: Patients with CSU, psoriasis with pruritic symptoms, and healthy volunteers were recruited in the study. Serum IL-31 levels were measured with commercial kits. Baseline characteristics, urticaria activity score, psoriasis area severity index, pruritic intensity score, and related laboratory results were collected. RESULTS: Sixty-five CSU patients, 30 psoriasis patients who had pruritus, and 31 healthy subjects participated in our study. The CSU patients had significantly higher mean serum IL-31 levels than the psoriasis patients (252.4 ± 115.5 vs 121.4 ± 16.6 pg/mL, P < 0.001). Both CSU and psoriasis patients also had significantly higher mean serum IL-31 when compared with the healthy subjects. Serum IL-31 levels of CSU and psoriasis patients did not differ significantly according to disease or itching severity. Thyroid antibodies and antinuclear antibodies were positive in 22 (33.8%) and 28 (43.1%) CSU patients, respectively. The CSU patients with ANA titers ≥1:160 had significantly higher mean serum IL-31 levels than in those who were negative for ANA and those with titers of 1:80 (P < 0.003 and P < 0.008, respectively). CONCLUSION: Higher serum IL-31 levels were found in patients with CSU and psoriasis with pruritic symptoms. This suggests that IL-31 has a possible role in the pathogenesis of CSU and psoriasis with pruritic symptoms.