Liquid crystalline nanodispersions as a siRNA carrier in the topical treatment of psoriasis: Evaluation in in vitro and in vivo models

Author(s)

Lívia Vieira Depieri

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Ciências Farmacêuticas de Ribeirão Preto (PCARP/BC)
• Defense date: 2016-08-05

Examining board members

Maria Vitoria Lopes Badra Bentley; Silvya Stuchi Maria Engler; Priscyla Daniely Marcato Gaspari; Marcelo Bispo de Jesus

• Advisor: Maria Vitoria Lopes Badra Bentley

Abstract

Gene therapy by RNA interference (RNAi) is a post-transcriptional gene silencing process in which specific small interfering RNA (siRNA) molecules can suppress the expression of a particular gene. Currently, is a promising therapeutic approach for the treatment of many severe disorders, including skin diseases. However, difficulties related to the administration and biodistribution limit the clinical use of siRNAs. In this context, a nanocarrier based in liquid crystal has been proposed to enable the application of siRNAs in the topical treatment of psoriasis. The liquid crystalline nanodispersion (LCN) developed, composed by monoolein, oleic acid, polyethylenimine and aqueous phase (8:2:1:89, w/w/w/w), was able to overcome the barriers of topical administration route, as well as limitations resulting from the characteristics of the siRNA molecules. The LCN was able to complex the siRNA, protect it for 24 h from enzymatic degradation and release it in an intact form. The LNC promoted a high cellular uptake of siRNA in fibroblasts and macrophages. Its topical application can be considered safe to the skin since viability of the reconstructed human epidermis remained above 50% and the amount of IL-1? released is less than 60 pg/mL. The LCN showed efficacy in promoting functional release of siRNA in in vitro models evaluated. In psoriatic reconstructed human skin model, it reduced the IL-6 levels (~ 70%) after a single treatment for 6 h and the mRNA IL6 levels (~ 50%) after treatment for 3 consecutive days. In macrophages, it reduced the mRNA Tnf levels in 40% after the concomitant treatment with LPS for 24 h and, in 60% with treatment for 24 h after prior stimulation with LPS. The efficiency was higher with the pretreatment for 24 h followed by stimulation with LPS, that normalized the RNAm Tnf levels. Topical treatment with NLC carrying siRNA Tnf was effective in reduce significantly the mRNA Tnf levels in in vivo models of skin acute inflammation induced by TPA (~ 60%) and of psoriasis induced by imiquimod (~ 90%) evaluated. In the in vivo model of psoriasis, topical treatment with the NLC carrying siRNA Tnf also significantly reduced activity of myeloperoxidase (~ 65%) and the epidermis thickness (~ 70%) compared to control groups. It has also been effective in animal phenotypic improvement, reducing redness, desquamation, acanthosis and the number of itch attacks, results of the reduction in inflammatory process obtained by the effective action of siRNA Tnf molecules. The LCN also promoted the penetration of siRNA molecules into the deeper layers of the skin in vivo. With the results obtained, we can conclude that the LCN is a relevant strategy for topical administration of siRNAs, which showed therapeutic potential to suppress specific genes related to skin diseases. (AU)

• FAPESP's process: 12/09125-8 - Liquid crystalline nanodispersions as a carrier of siRNA in the topical treatment of psoriasis: In vitro and in vivo evaluation and elucidation of the mechanisms of cellular uptake
• Grantee: Lívia Vieira Depieri
• Support Opportunities: Scholarships in Brazil - Doctorate