Expression of precipitating factors of pruritus found in humans in an imiquimod-induced psoriasis mouse model

AIMS: To use a mouse model of imiquimod-induced psoriasis to investigate the relationship between pruritus and mast cells, nerve growth factor (NGF) and endogenous pruritogenic peptides, which are highly expressed in the skin of psoriasis patients. MAIN METHODS: We developed a mouse model of imiquimod-induced psoriasis and measured the frequency and duration of the model animals’ self-scratching behavior using the SCLABA(®)-Real real-time scratch counting system. We then harvested the ears and subjected them to toluidine blue staining and real-time PCR. KEY FINDINGS: Topical application of imiquimod increased the Psoriasis Area and Severity Index score as well as the frequency and duration of self-scratching. Regarding internal factors, increases in mast cells number and mRNA expression of NGF and endogenous pruritogenic peptide precursor were confirmed. SIGNIFICANCE: Self-scratching behavior is accompanied by increased number of mast cells and expression of NGF and endogenous pruritogenic peptides in our imiquimod-induced psoriasis model. The expression of these factors was consistent with the features in patients with pruritic psoriasis, suggesting that our model reflects at least some of the precipitating factors of pruritus found in humans.