LGR4 Deficiency Aggravates Skin Inflammation and Epidermal Hyperplasia in Imiquimod-Induced Psoriasis.

Psoriasis is a chronic inflammatory skin disease characterised by inflammatory cell infiltration, keratinocyte hyperproliferation and increased neovascularization. Despite extensive research, the precise mechanisms underlying psoriasis pathology and treatment strategies remain unclear because of a complex aetiology and disease progression. Hence, in this study, we aimed to identify potential therapeutic targets for psoriasis and explore their effects on disease progression. We observed that G protein-coupled receptor LGR4 attenuates psoriasis progression. Bioinformatics analysis of publicly available clinical data revealed lower LGR4 expression in the skin lesions of patients with psoriasis than in their non-lesioned skin. Both in vitro (HaCaT cell) and in vivo (mouse) models confirmed this phenomenon. The Lgr4-knockout mouse model further confirmed that LGR4 plays a positive role in psoriasis progression. Specifically, Lgr4 knockout promoted the secretion of inflammatory factors, accumulation of local immunocyte infiltration in skin lesions, and keratinocyte proliferation. In conclusion, we demonstrated that LGR4 is critical to limiting psoriasis progression, suggesting that it is a viable target for the clinical management of this skin condition.