Transdermal delivery of Fn14 siRNA using a novel composite ionic liquid for treatment of psoriasis-like skin lesions

Psoriasis is a chronic inflammatory skin disease characterised by the abnormal proliferation of keratinocytes and dysregulation of immune cells. The upregulation of fibroblast growth factor-inducible molecule 14 (Fn14) in psoriatic lesions has been linked to the development of psoriasis. Transdermal delivery of siRNAs for Fn14 inhibition is challenging. In this study, we developed a composite ionic liquid (CIL) for the transdermal delivery of Fn14 siRNA (siFn14) into keratinocytes, with the aim of modulating the inflammatory response associated with psoriasis. The results showed that CIL-siFn14 effectively suppressed Fn14 expression, resulting in a reduction in both the Psoriasis Area and Severity Index (PASI) score and skin thickness. Furthermore, CIL-siFn14 effectively inhibited the abnormal proliferation of keratinocytes, decreased the production of inflammatory factors associated with psoriasis, prevented the over-activation of CD4+ and CD8+ T cells, and restored the balance of Type 1 T helper (Th1), Th2, Th17 and Treg cells. In conclusion, our findings unveiled the critical role of Fn14 in the pathogenesis of psoriasis and demonstrated the potential of CIL-siFn14 as a novel and effective topical treatment for its management.