In preclinical in vivo studies, indirubin showed better performance in improving the phenotype of psoriasis-like mice compared to that in controls, including the PASI score (mean difference [MD] = −3.58, p < .0001), epidermal thickness (MD = −29.13, p < .0001), interleukin-(IL) 17 A mRNA expression (MD = −2.27, p = .0066) and IL-23 mRNA (MD = −5.36, p = .01). This evidence concerns the gene IL23A and psoriasis.