Effect of anti-interleukin-17 biologics on Krebs von den Lungen-6 level in patients with psoriasis.

Interleukin (IL)-17 plays critical roles in the pathogenesis of both psoriasis and interstitial pneumonia (IP). We hypothesized that anti-IL-17 biologics might suppress both clinically relevant and latent IP activity and decrease Krebs von den Lungen-6 (KL-6) level in psoriasis patients. We aimed to elucidate the effects of anti-IL-17 biologics on KL-6 levels. We retrospectively analyzed the clinical data of psoriasis patients treated with anti-IL-17 biologics. KL-6 levels were measured before treatment (baseline) and at 3 and 6 months after the initiation of the treatment, and ratios of KL-6 levels at each time point to the baseline levels were calculated. Chest computed tomography (CT) was performed on patients with coexisting IP. The clinical characteristics and radiographic findings were evaluated. A total of 294 psoriasis patients were treated with anti-IL-17 biologics. Baseline KL-6 levels were higher than 401 U/mL in 34 patients (high baseline KL-6 group). While anti-IL-17 biologics did not affect KL-6 levels and ratios of KL-6 to the baseline levels at any time point in the overall study population, they decreased both KL-6 levels and ratios at 6 months after the initiation of the treatment in the high baseline KL-6 group. A total of 10 patients with coexisting IP showed decreasing ratios of KL-6 to the baseline levels at 6 months without affecting coexisting IP in CT performed at 3-12 months. Anti-IL-17 biologics decreased KL-6 levels in the high baseline KL-6 group regardless of recognizable IP. A decrease in KL-6 levels was not associated with a radiographic improvement of IP, which should be examined in large numbers with long-term observations in future studies.