Histopathological Observation and Psoriasis area Severity Index Scoring of Imiquimod-induced Psoriasis in Experimental Animals

Atopic dermatitis and psoriasis are inflammatory skin conditions that affect close to 3% of the global population. Rats are research animals that are very useful as research media. Imiquimod (IMQ) is an immune activator often used ion or molecule known as a ligand for Toll-Like Receptors 7 (TLR7), including Toll-Like Receptors (TLRS). In addition, imiquimod has a psoriasis-like inflammatory effect. This study aims to develop psoriasis mice implementing the inducing chemical with Imiquimod (IMQ). This study assesses Psoriasis Area Severity Index (PASI) and histopathology scores after administering IMQ to the study rats. The PASI score is observed every three days until the ninth day. The hair on the Wistar rats’ back was continuously removed and given 62,5 mg IMQ 5% cream for nine days. Furthermore, the area severity index of psoriasis uses induration (thickness), the level of erythema (redness) and desquamation (scaling) on every skin rat. Then, histopathology was observed in each rat. The erythema signs, thickening, and scales appear on the back's skin on the third until sixth days following IMQ administration. The maximum score was seen on day 9, with all three indicators and the cumulative score indicating increased physical characteristics. Microscopically, it showed thickening of the stratum corneum (hyperkeratosis), epidermal hyperplasia (acanthosis), increased skin vascularity, and inflammatory infiltration of mast cells, macrophages, and inflammatory lymphocytes. This research succeeded in developing Wistar rats as a model for causes of skin inflammation, such as psoriasis induced by IMQ 5% as an inducing agent to psoriasis.