NETs contribute to psoriasiform skin inflammation: a novel therapeutic approach targeting IL-36 cytokines by a small molecule tetrahydroxystilbene glucoside

Psoriasis, a chronic immune-mediated skin disease with pathological features such as aberrant differentiation of keratinocytes, dermal-epidermal inflammation, and angiogenesis. 2,3,5,4′-Tetrahydroxy stilbene 2-Ο-β-D-glucoside (2354Glu) is a natural small molecule polyhydrostilbenes isolated from Polygonum multiglorum Thunb. The regulation of IL-36 subfamily has led to new pharmacologic strategies to reverse psoriasiform dermatitis. Here we investigated the therapeutic potential of 2354Glu and elucidated the underlying mechanism in psoriasis. The effects of 2354Glu on IL-36 signaling were assessed by psoriasiform in vivo, in vitro and ex vivo model. The in vivo mice model of psoriasis-like skin inflammation was established by applying imiquimod (IMQ), and the in vitro and ex vitro models were established by stimulating mouse primary keratinocyte, human keratinocytes cells (HaCaT) and ex vivo skin tissue isolated from the mice back with Polyinosine-polycytidylic acid (Poly(I:C)), IMQ, IL-36γ and Lipopolysaccharide (LPS) respectively. Moreover, NETs formation was inhibited by Cl-amidine to evaluate the effect of NETs in psoriatic mouse model. The effects of 2354Glu on skin inflammation were assessed by western blot, H&E, immunohistochemistry, immunofluorescence, enzyme-linked immunosorbent assay and real-time quantitative PCR. In Poly(I:C)-stimulated keratinocytes, the secretion of IL-36 was inhibited after treatment with 2354Glu, similar to the effects of TLR3, P2 × 7R and caspase-1 inhibitors. In aldara (imiquimod)-induced mice, 2354Glu (100 and 25 mg/kg) improved immune cell infiltration and hyperkeratosis in psoriasis by directly targeting IL-36 in keratinocytes through P2 × 7R-caspase-1. When treatment with 2354Glu (25 mg/kg) was insufficient to inhibit IL-36γ, NETs reduced pathological features and IL-36 signaling by interacting with keratinocytes to combat psoriasis like inflammation. Conclusion: These results indicated that NETs had a beneficial effect on psoriasiform dermatitis. 2354Glu alleviates psoriasis by directly targeting IL-36/P2 × 7R axis and NET formation, providing a potential candidate for the treatment of psoriasis.