GPR15 is not critically involved in the regulation of murine psoriasiform dermatitis.

GPR15 L expression is induced in psoriasiform dermatitis, but the activation of the IL-23/IL-17 axis alone is not sufficient for its induction. This restricts the potential use of GPR15 L levels as biomarker for the treatment response to anti-IL-17 antibody therapy. Our results leave a significant role of GPR15 in the pathogenesis of psoriasiform dermatitis rather unlikely. Hence, GPR15 L probably modulates psoriasiform dermatitis via GPR15-independent pathways.