CAT and psoriasis: As the sponsor of OS in psoriasis, ROS from skin induce the expression of inducible nitric oxide synthase (iNOS), MDA and nitric oxide (NO), while inhibit the activity of SOD, CAT and GSH-Px, further activating Th1/Th17 cells and keratinocytes through stimulation of MAPK, NF-κB and JAK-STAT pathways [68, 69], thereby producing the cascade of inflammatory factors.