Although there are many sources of ROS (e.g., NADPH oxidases [NOX], mitochondrial ETC, xanthine oxidase, uncoupled endothelial nitric oxide synthase [eNOS], cytochrome P-450 oxygenase, and cyclooxygenase), there remains a lack of clarity regarding the specific ROS pathway involved in the exacerbation of psoriasis (60, 62). Here, XDH is linked to psoriasis.