IL17A and dry eye syndrome: Recently, increasing reports have shown that there is a decrease in the antioxidants containing SOD, CAT and GSH from psoriasis patients, whereas an increase in oxides like ROS, MDA and NO [34]; this imbalance of the oxidative/anti-oxidative system triggers OS and excites OS/ inflammation-related signals, which stimulate several cells, mainly T cells and DCs, to secrete a variety of inflammatory mediators/cytokines (e.g. IL-17, IL-23, VEGF, TNF-α, TGF-β, and IFN-γ), eventually leading to KCs hyper-proliferation, inflammatory cells infiltration, and neovascularization [35,36].