The in vivo model is acute and reflects inflammatory and epithelial changes which occur in psoriatic human skin. The disease phenotype is induced via topical application of imiquimod cream. Disease is assessed over a 5-8 day period using a Psoriasis Activity Severity Index (PASI) scoring system encompassing redness, swelling and thickness of the skin. The effect of novel therapeutic agents can also be assessed using the ex vivo analyses detailed below.
- Histopathology of epidermis and dermis
- Phenotypic analysis of immune cells
Each employs flow cytometry, immunohistochemistry, multiplex analysis of key cytokines and factors, gene expression.
In vitro models involve stimulation of human primary keratinocytes with a cocktail of pro-inflammatory cytokines which can induce a gene expression profile that mimics that of psoriasis patients. The effects of novel therapeutic agents on gene and protein expression associated with the induced inflammation can then be examined.