Effects of MEDD on symptom severity in IMQ-induced psoriasis model mice. The dorsal skin of mice was treated with Vaseline, imiquimod (IMQ), IMQ and Vh or MEDD for 7 days, and the phenotype was observed the next day. a Representative macroscopic views of the dorsal skin of each group of mice. b Calculation of spleen weight per body weight for each treatment group. Each dot represents one mouse. c Hematoxylin and eosin staining of paraffin sections from the dorsal skin of each group of mice. Note: Munro’s abscess (asterisk), parakeratosis (arrowhead), and rete ridge (arrow). Scale bar: 100 μm d Microscopic measurement of epidermal thickness (μm) of dorsal skin. e Individual histological scoring of thickness, immune cell infiltration, and parakeratosis in the skin. b, d, e These results represent mean ± S.D. of four independent experiments. a, c The photograph is representative of four independent experiments. Statistical analysis was performed using Student’s t-test. * p < 0.05; ** p < 0.01, compared with mice in the IMQ- and vehicle-treated group; ###, p < 0.001, compared with Vaseline control mice; IMQ, imiquimod; Vh, Vehicle; MEDD, methanol extract of Dictamnus dasycarpus root bark.