Inhibition of phospholipases suppresses progression of psoriasis through modulation of inflammation

Abnormal lipid metabolism is regarded as a crucial cause of psoriasis. The specific mechanism of how phospholipase PLA2G4B mediates local immune dysfunction and skin lesions remains unclear. The aim of this study was to explore the mechanisms of anti-psoriasis and immune suppression effect by inhibiting PLA2G4B in psoriasis progression. We successfully transfected si-PLA2G4B in a murine keratinocyte cell-line PAM212 to verify the effect of progression by PLA2G4B. The Imiquimod psoriasis mouse model was then successfully constructed, followed by emulsion wrapped PLA2G4B-siRNA applied to the skin lesions. The phenotype, pathology, immunofluorescence staining of PLA2G4B, IL17, CD3, and CD1b, and bulk transcriptome analysis were performed to decipher the effect and mechanism of si-PLA2G4B. Interfering with PLA2G4B significantly inhibited the proliferation and migration of PAM212. The interference of PLA2G4B in vivo showed a therapeutic effect on psoriasis, comparable to that of betamethasone. The phenotype and pathology revealed reduced keratinocytes in the si-PLA2G4B group compared to the model mice. Immunofluorescence showed that CD1b, CD3+ T cells, and IL17 were suppressed in the skin lesions. RNA-seq and deconvolution revealed that immune cells such as myeloid dendritic cell and T cell CD8+ naive were inactivated. Th17 reduce the release of inflammatory factors such as IL17 and IL36. Pathway analysis revealed the potential therapeutic mechanism involved in the inhibition of sphingolipid or ceramide secretion. This study verified the anti-psoriatic effect of using si-PLA2G4B. The immune response was alleviated after administration. This phospholipase inhibition-based therapy sheds light on the pharmaceutical potential against psoriasis.