Effect of melittin in C. acnes-induced acne models. (A) Live C. acnes (1 × 107 CFU) were inoculated into the ears of mice together with or without melittin. At 24 h after injection, the representative images of the ear were photographed. (B) The mice exhibited cutaneous erythema (or edema and redness), a typical symptom of ear inflammation. Formalin-fixed ear tissue sections were stained with H&E, and the infected areas were quantified. (C) Relative evaluation of redness, a typical symptom of acne, was performed. Histological examinations were performed at 400× magnification. Scale bar = 50 μm. The figures are representative of each study group (six mice per group). The results are expressed as means ± SEM. * p < 0.05 compared with the NC group. † p < 0.05 compared with the CA group. NC: normal control; CA: C. acnes; M1, M10, and M100: 1, 10, and 100 μg of melittin mixed with Vaseline and applied topically to the ear surface.