IL17A and psoriasis: In this study, we detected the increased serum levels of HMGB1, TLR4, IL‐23, and IL‐17A and evaluated the positive correlation between HMGB1 and TLR4, HMGB1 and IL‐23, HMGB1 and IL‐17A, as well as TLR4 and IL‐23 and TLR4 and IL‐17A, which indicates that HMGB1‐TLR4‐IL‐23‐IL‐17A pathway may produce a pathogenic effect on psoriasis.