Besides, it is reported that IL-22 helps maintain the homeostasis of the host immune system and induces immune tolerance by preventing colonization by pathogenic microorganisms.519 Considering the dysregulation of gut microbiota plays an important role in psoriasis,520 we hypothesize that the dysfunction of gut microbial homeostasis may be another reason for the failure of targeting IL-22. The gene discussed is IL22; the disease is psoriasis.