Serum interleukin-22 and vascular endothelial growth factor serve as sensitive biomarkers but not as predictors of therapeutic response to biologics in patients with psoriasis.

The T-helper (Th)17 cell plays a crucial role in the pathogenesis of psoriasis, and several biological therapies have shown to be highly efficient in the treatment. However, some patients respond poorly to these therapies and may even develop paradoxical adverse effects. To evaluate the significance of serum immunological factors or circulating competent cells for biomarkers or predictors to biological therapies, we retrospectively analyzed 28 patients with psoriasis (19 psoriasis vulgaris, three pustular psoriasis and six psoriasis arthropathica). The numbers of patients treated with each agents were 16 for ustekinumab, six for adalimumab and six for infliximab. Patients were classified into three types according to the responsiveness: 13 patients were high-responders showing a 75% or more reduction of Psoriasis Area and Severity Index (PASI); 10 patients were moderate-responders showing PASI reduction of less than 75%; and five patients were non-responders showing PASI elevation. During the treatments, serum levels of interleukin (IL)-22 and vascular endothelial growth factor (VEGH) [corrected] were monitored. At baseline, serum IL-22 levels were significantly higher in the psoriatic patients than the normal controls. Both serum IL-22 and VEGF levels significantly correlated with PASI. After the treatment, the high-responders showed significant decreases in serum IL-22 and VEGF. On the other hand, serum IL-22 levels in the non-responders were elevated. However, the baseline levels of serum IL-22 and VEGF were not significantly different between the three groups. These results suggest that serum IL-22 and VEGF levels serve as sensitive biomarkers but not as predictors of therapeutic response to biologics in patients with psoriasis.