IL-17 regulates IL-36 expression, and in turn, IL-36 potentiates the function of IL-17 [22]. Additionally, IL-36 signaling is a potent inducer of IL-23 [23]. IL-36 cytokines are activated by proteolytic cleavage by enzymes such as cathepsin G, elastase, and proteinase-3. In GPP, IL-36 cytokines can stimulate keratinocytes to produce chemokines that recruit neutrophils [18]. Thus, IL-36 plays a crucial role in the pathogenesis of GPP, and biologics targeting IL-36 are expected to provide beneficial effects in cases of refractory GPP [24,25]. Here, CTSG is linked to psoriasis 14, pustular.