Imiquimod-Induced Psoriasis (Rats and Mice)

Psoriasis is the most prevalent immune-mediated skin disease in adults, and affects approximately 25 million people in North American and Europe alone¹. Psoriasis is a complex, multifactorial disease and the exact mechanism of psoriasis is not yet fully understood^1,2. In the past, most psoriasis research was performed in a xenotransplant model, where skin from a psoriasis patient is grafted onto immunodeficient mice. Although this model is useful, these experiments are laborious, expensive, and require considerable expertise and technical skill^3,4. The development of the imiquimod-induced model of psoriasis is a simple, acute, cheap model that has been used with increasing frequency to better understand the inflammatory process leading to psoriasis, as well as a high-throughput screening of potential therapeutic agents^3,5.

Induction: 

Starting on Study Day 0 and continuing daily for the duration of the study, 75mg (mice) or 150mg (rats) of 5% imiquimod cream is applied to the shaved skin on the back.

Disease Parameters/Progression: 

In mice, redness and scaling significantly increase by Study Day 6; whereas visual thickening score and caliper measurements increase at day 4.

Dosing Paradigms:

• Prophylactic (Developing) – Dose prior to daily IMQ.
• Established (Therapeutic) – Dose after IMQ.
• Route of administration: Topical, SC, PO, IP, IV

Clinical Assessment: 

PASI Scoring
Every other day animals are scored for erythema, scaling, and skin thickening as follows:

• 0 = None
• 1 = Slight
• 2 = Moderate
• 3 = Marked
• 4 = Very Marked

Skin caliper measurements are also taken every other day using a Digitrix II micrometer. Biopsy punches of the skin may also be taken and weighed.

Sample Data (Click on image to enlarge):

Mouse Clinical

Mouse Photographs

Rat Clinical

Rat Photographs