Imiquimod-induced skin inflammation

Mice were acclimatized to their environment for 2 weeks before the experiments. The animals were randomly allocated into treatment and vehicle group (n = 7 per group). In the experiment with H4R^−/− mice, n = 6 H4R^−/− mice and n = 6 wild-type mice were used. Sample size calculation was performed by power analysis using G*power 3.1.9.2. for Windows (alpha value 0.5, power 80%, Cohen’s d effect size 0.8). A co-worker blinded to the experimental protocol randomized animals into these groups. Mice were treated with Aldara™ (MEDA Pharma GmbH & Co. KG, Bad Homburg, Germany) cream (containing 5% IMQ) to induce psoriasis-like skin inflammation. This is referred as “IMQ” throughout the current paper. Mice were killed 24 h after the last application of IMQ or soft cream. Mice were killed by inhalation of isoflurane, followed by cardiac puncture for blood collection. Animal experiments were performed in accordance with the recommendations in the ARRIVE guidelines (https://arriveguidelines.org/).