IL-33 Contributes to the Pathological Changes of Hair Follicles in Psoriasis: A Potential Target for Psoriatic Alopecia

The study explored the role of IL-33 in the development of psoriatic alopecia by examining its effects on hair follicles (HFs) in both human psoriasis patients and imiquimod (IMQ)-induced psoriatic mice. Increased IL-33 expression was found in the keratinocytes of the outer root sheath of HFs in both psoriasis patients and psoriatic mice. Using IL-33 and ST2 knockout mice, the research demonstrated that the absence of IL-33 or its receptor ST2 reduced the pathological changes and T cell infiltration in psoriatic HFs. Conversely, subcutaneous injections of recombinant IL-33 worsened these pathological changes and increased T cell infiltration. RNA sequencing and RT-PCR confirmed that IL-33 upregulated genes associated with keratinocyte proliferation and T lymphocyte chemotaxis. The study concludes that IL-33 contributes to the pathological changes in HFs seen in psoriasis and suggests that targeting IL-33 could be a potential treatment strategy for psoriatic alopecia.