Topically-delivered Targeted Gene Suppression of Immune Activation in Psoriasis

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DESCRIPTION (provided by applicant): AuraSense Therapeutics (AST), along with Northwestern University, is applying a recently developed technology using oligonucleotide-functionalized nanoparticles (called spherical nucleic acids or SNAs) to control protein expression. These easily synthesized nanoparticles can have either DNA or RNA shells, and are less than 50 nm in hydrodynamic diameter. SNA constructs are a powerful new way of regulating gene expression. Significance Conventional drug development is an increasingly expensive proposition. In recent years, pharmaceutical manufacturers have pursued gene regulation's potential with aggressive efforts to generate therapeutic leads for cancer. Identification of target genes has proceeded quickly, but the pharmaceutical industry as a whole faces major challenges involving the safe and effective use of oligonucleotide-based gene regulation technology. The major barriers include nucleic acid stability, immune-related toxicity, and delivery challenges. Oligonucleotides are subject to degradation while circulating in the bloodstream and upon entry into cells. Preserving their stability is critical for therapeutic application of any gene regulation strategy. Unfortunately, the "naked" genetic sequences used in traditional gene regulation are not only unstable, but elicit an immune response, leading to extremely short half-lives and poor efficacy. For treating skin disorders, topical delivery is idea, not only by concentrating the intervention at the disease site, but also by minimizing the risk of systemic toxicity; the epidermal barrier has generally precluded the entry of nucleic acids into skin. The Product SNA constructs consist of a dense spherical array of highly oriented oligonucleotides, templated on a nanoparticle. These materials have already proven to be remarkable in that they readily enter cells, resist nuclease degradation, have low toxicity and lead to minimal immunostimulation. Critically, SNAs are also capable of penetrating the stratum corneum and knocking down targets in the epidermis, making them potentially very powerful tools to treat skin diseases. Leveraging recent cutting-edge discoveries about the key roles of IL-17 and IL-22 cytokines in the development of psoriasis, AST and Northwestern will design SNAs that concurrently target the skin-based receptors for these cytokines (IL17RA and IL22RA1) as topical treatment of psoriasis. These SNAs will be evaluated for gene knockdown potency, toxicity and therapeutic effect in vitro and in a mouse model of the disease. Long Term Goal After a period of initial development, AST aims to commercialize the SNA technology by partnering with a large pharmaceutical company such as Abbvie, Novartis or Merck. The Specific Aims of this proposal are the following: Aim 1: Generate IL17RA/IL22RA1 SNAs that efficiently suppress gene targets in mouse and human keratinocytes. AST will design and test SiRNA containing SNAs that target mouse and human IL17RA and IL22RA1, key receptors in the psoriasis inflammation pathway. The efficacy of the SNAs will be measured by the reduction in mRNA and protein levels in keratinocytes treated with targeted SNAs vs. SNAs functionalized with non-targeting siRNA duplexes. Aim 2: Evaluate the effect of IL17RA, IL22RA1 and IL17RA/IL22RA1 hybrid SNAs on a reconstituted human epidermis (RHE) model of psoriasis. Using a cytokine-induced human 3-D model that histologically, biochemically, and genetically resembles psoriasis, the most potent individual and hybrid human SNAs identified in Aim 1 will be further assessed. SNA efficacy will be evaluated based on the reduction in mRNA and protein expression of targeted receptors and the downstream products of cytokine activation, as well as by correction of the abnormal differentiation seen in psoriasis. Aim 3: Evaluate the abilit of IL17RA/IL22RA1 SNAs to suppress the psoriatic phenotype in a mouse model. We will test the ability of the most efficacious IL17RA and IL22RA1 SNAs, as identified in Aims 1 and 2, to prevent and treat psoriasis using an imiquimod-induced model. Relationship to Phase II Work: Should these studies show promise, we will further test the efficacy of SNAs in two additional mouse models (induction of psoriasis in mouse ears by IL-23 and a humanized mouse system with human epidermal grafting), initiate pre-clinical toxicity studies and, ideally, apply for an ID for these SNAs.