OAS1, OAS2, and OAS3 Contribute to Epidermal Keratinocyte Proliferation by Regulating Cell Cycle and Augmenting IFN-1‒Induced Jak1‒Signal Transducer and Activator of Transcription 1 Phosphorylation in Psoriasis.

Psoriasis is a systemic immune‒mediated inflammatory disease characterized by hyperproliferation and abnormal differentiation of epidermal keratinocytes. Recent studies have identified IL-17 and IL-23 as key drivers of psoriasis pathogenesis, but the underlying molecular mechanisms remain unclear. The 2'-5'-oligoadenylate synthetases (OASs), namely, OAS1, OAS2, OAS3, and OASL, are a family of IFN-induced enzymes with multiple antiviral activities, but their role in psoriasis is unknown. In this study, we identified the overexpression of OAS1, OAS2, and OAS3 in human lesional psoriatic skin and serum and found that their expression was downregulated by biologics. Moreover, OASs were highly expressed in epidermal keratinocytes, epidermal dendritic cells, epidermal CD3 T cells, dermal antigen-presenting cells, and dermal T cells from the psoriatic epidermis and dermis, as determined by flow cytometry. In addition, OASs were upregulated by poly(I:C), poly(dA:dT), and IFN-1s but downregulated by Jak inhibitors in normal human epidermal keratinocytes. Furthermore, silencing of OASs inhibited the phosphorylation of Jak1 and signal transducer and activator of transcription 1. Knockdown of OASs suppressed keratinocyte proliferation by inhibiting cell cycle progression. Thus, OASs may be therapeutic biomarkers in psoriasis.