 Similarly, genetically modifying mice to not express IL-23 or IL-17 receptors significantly reduced psoriatic lesion development upon stimulation with the lesion-causing tumor promoter 12-O-tetradecanoylphorbol-13-acetate.IL-17 promotes psoriasis by contributing to the inflammatory response that damages and overturns the keratinocyte cells of the epidermal layer.Inflammation begins with keratinocyte cells entering the final stages of their cell cycle, which activates immature dendritic cells (DC).