Keratinocyte HIF-1α Orchestrates Imiquimod-Induced Psoriasiform Inflammation by Promoting Type 3 Inflammation

Psoriasis is a chronic inflammatory skin disease driven by the IL-23/IL-17 axis and characterized by keratinocyte hyperproliferation, epidermal thickening, and immune infiltration. While immune cell-intrinsic roles of hypoxia-inducible factor-1α (HIF-1α) have been reported, the contribution of keratinocyte HIF-1α remains less clear. In this study, we investigated epithelial HIF function in murine models of skin inflammation using keratinocyte-specific HIF-1α knockout (K14-Cre Hif1a^fl/fl) mice. HIF-1α deficiency attenuated epidermal hyperplasia and type 3 inflammation in the imiquimod (IMQ)-induced psoriasiform model but had little effect in DNFB-induce contact hypersensitivity and MC903-induced atopic dermatitis model. Flow cytometry of draining lymph nodes revealed reduced frequencies of inflammatory cells including IL-17-producing γδ T cells in HIF-1α-deficient mice. In IMQ-treated skin, HIF-1α deficiency led to reduced Il17, Il23 and neutrophil-attracting chemokine transcript levels and diminished Ly6G⁺ neutrophil infiltration. These findings identify keratinocyte HIF-1α as a central regulator of psoriasiform inflammation and suggest that epithelial HIF signaling could be a potential therapeutic target for psoriasis.