Also, it was highlighted that in psoriasis there is up-regulation of Th17 and down-regulation of regulatory T cells (Treg), which is evidenced by up-regulation of retinoic-acid-receptor-related orphan nuclear receptor gamma (ROR-ɤ) and down-regulation of fork head box P3 (FOXP-3) (Fitch et al. 2007; Shi et al. 2019). Here, FOXP3 is linked to psoriasis.