IL-27 signaling mediates skin inflammation in experimental psoriasis and atopic dermatitis.

BACKGROUND: Psoriasis and atopic dermatitis (AD) are two prevalent inflammatory skin disorders, each characterized by distinct adaptive immune responses. However, recent evidence suggests that these diseases may share overlapping immune mechanisms, especially concerning keratinocyte function. The specific cytokines that coordinate these inflammatory pathways remain largely undefined. METHODS: The expression of IL-27 and its receptor was analyzed using data derived from GEO datasets. Imiquimod-induced psoriasis-like and MC903-induced AD-like skin inflammation models were established in wild-type and Il27ra knockout littermates. Skin inflammation was evaluated using clinical scoring, histology, and immunostaining. Flow cytometry was employed to characterize immune cell populations in skin. Expression of relevant cytokines and signaling molecules was assessed using quantitative PCR, bulk RNA sequencing, and Western blotting. RESULTS: We found significantly elevated expression of the IL-27 receptor in the lesional skin of patients with psoriasis or AD. IL-27 receptor-deficient mice exhibited markedly reduced skin inflammation in both psoriasis-like and AD-like murine models. Mechanistic investigations revealed that IL-27 induces tumor necrosis factor-α production via signal transducer and activator of transcription 1 activation in keratinocytes, thereby potentiating inflammatory responses. CONCLUSIONS: Our findings identify IL-27 signaling in keratinocytes as a pivotal regulator of skin inflammation in both psoriasis and AD. This highlights IL-27 as a promising therapeutic target for inflammatory skin diseases.