A common, chronic skin disease, affecting approximately 2% of the population in the world. Autoreactive disease characterized by chronic inflammation in the absence of known infectious agents or antigens.

Hyper-proliferative epidermis + dermal inflammatory infiltrate. Dendritic cells and possibly macrophages are key constituents of the inflammatory process.

Th1/Th17 cells are critical to disease.

Treatment of psoriasis is still based on controlling the symptoms. Topical and systemi therapies, as well as phototherapy, are available. The need for treatment is usually lifelong and is aimed at remission. Some systemic therapies, although effective, have significant adverse effects.

AOM (Methyl-methylimino-oxidoazanium, CH₃N =N(→O)CH3 ) is a procarcinogen that is metabolized by cytochrome p450, isoform CYP2E1, converting it into methylazocymethanol (MAM), a highly reactive alkylating species that induces O⁶ methylguanine adducts in DNA resulting in G -7 A transitions.

DSS is a heparin-like polysaccharide that is dissolved in the drinking water and inflicts colonic epithelial damage, inducing colitis mimicking some of the

features of IBD.

Combining AOM and DSS provides a two-step tumor model of colorectal cancer (CRC).