Treating psoriasis by targeting its susceptibility gene Rel

• Nanoparticle-loaded siRNA accumulated in lymphoid organs.
• c-Rel-specific siRNA can be used to prevent & treat imiquimod induced psoriasis.
• c-Rel-specific siRNA down-regulates the expression of inflammatory cytokines.
• c-Rel may be a potential therapeutic target for psoriasis prevention & treatment.

Psoriasis is a chronic inflammatory disorder of the skin. Accumulating evidence indicates that the Rel gene, a member of the NF-κB family, is a risk factor for the disease. We sought to investigate whether psoriasis can be prevented by directly targeting the Rel gene transcript, i.e., the c-Rel mRNA. Using chemically-modified c-Rel specific siRNA (siRel) and poly(ethylene glycol)-b-poly(l-lysine)-b-poly(l-leucine) (PEG-PLL-PLLeu) micelles, we successfully knocked down the expression of c-Rel, and showed that the expression of cytokine IL-23, a direct target of c-Rel that can drive the development of IL-17-producing T cells, was markedly inhibited. More importantly, treating mice with siRel not only prevented but also ameliorated imiquimod (IMQ)-induced psoriasis. Mechanistic studies showed that siRel treatment down-regulated the expression of multiple inflammatory cytokines. Taken together, these results indicate that the susceptibility gene Rel can be targeted to treat and prevent psoriasis.