Using siRNA-based spherical nucleic acid nanoparticle conjugates for gene regulation in psoriasis

Psoriasis is a T-cell-mediated skin disease with autoimmune nature that is generally not observed in animals, this lack of a relevant experimental animal model of psoriasis has hindered the investigation of pathogenesis of disease. Application and systemic delivery of small interfering RNAs offer many effective therapeutic advantages for gene regulation in the skin. In this study, we present an IMQ animal model of psoriasis and designed a safe fusion peptide carrier, spherical nucleic acid gold nanoparticles conjugate, to improve penetration of the siRNA into the cells and skin and their targeting ability to gene regulation. We evaluated the model of psoriasis and EGFR siRNA treatment (as spherical nucleic acid nanoparticles), phenotypically (signs of erythema, scaling, inflammation and thickening), microscopic evaluation of cell proliferation and immunohistochemically evaluation of CD3, CD4, and CD8 markers. Also, we monitored suppression of EGF&EGFR genes after treatment of A431 cells by SNA-NCs. The expression of genes was validated by qRT–PCR in human skin cells. The results showed that the SNA-NCs were stable and non-toxic. In vitro experiments indicated that EGF&EGFR siRNAs conjugated with spherical nucleic acid gold nanoparticles can significantly reduce gene expression in cells. In vivo experiments showed that the topical application of siRNAs delivered by SNA-NCs through the skin can significantly inhibit the proliferation of cells. Microscopic evaluation of mice back skin and immunohistochemistry process approved Inhibitory effect of SNA-NCs siRNA in the mouse model of psoriasis. Since the proliferation of T cells was crucial for the development of a psoriatic phenotype. These results demonstrate that topical application of SNA-NCs siRNA may improve psoriatic-like skin lesions by suppressing gene expression and functional activity of T cell production.