Optimization of psoriasis mouse models

Psoriasis, is a common, chronic, autoimmune, inflammatory, relapsing disease, which would benefit from reliable and human-relevant animal models to test drugs pre-clinically and to understand their mechanism of action. Because of its ease of use, convenience and low cost, the imiquimod (IMQ)-induced psoriasis-like model is widely utilized; however, it is not known whether all mouse strains are equivalent and if the hairless mouse is appropriate, so that the imiquimod model can be further optimized. Under similar experimental conditions, common mouse strains (BALB/c, C57BL/6J, and ApoE) and a new hairless strain (ApoE/SKH-hr2) as well as several inducers (IMQ, IMQ + acetic acid (AcOH) topical and IMQ + AcOH systemic) were compared by clinical, histopathological, biophysical and locomotor activity assessments. The BALB/c mice yielded an optimal psoriasis-like phenotype with IMQ + AcOH topical treatment, and the corresponding phenotypes for the other mouse strains were C57BL/6J moderate and ApoE mild. In contrast, the ApoE/SKH-hr2 mice, as a result of the absence of a Munro abscess in the histopathology analysis, left doubt about the psoriasis-like acquisition. Locomotor activity of BALB/c mice treated with IMQ, IMQ + AcOH topically and IMQ + AcOH systemically showed decreased distance and rearing coverage and increased immobility with all treatments. Hence, the BALB/c mouse strain appears to be an optimal psoriasis-like model when utilizing IMQ + AcOH topical application.