【Animal modeling】-Comparison of imiquimod on the induction of psoriasis-like skin lesions in BALB/c and C57BL/6 mice

  Objective: To observe the difference and mechanism of imiquimod in the induction of psoriasis-like skin lesions in different strains of mice.

  Methods: Two mouse strains, BALB/c and C57BL/6, were selected, and 62.5 mg of Mingxin Lidi cream containing 5% imiquimod was applied on their backs respectively. After 6 days of application, the back skin of mice was observed by PAIS score. Morphological changes; HE staining was used to observe the histopathological changes of the applied skin, and epidermal thickness was measured under a microscope; the relative expression of IL-23/IL-17 axis-related cytokines was determined by real-time fluorescence quantitative PCR.

  Results: With the increase of imiquimod application days, the back skin of BALB/c mice and C57BL/6 mice gradually appeared psoriasis-like manifestations such as scaling, erythema, and epidermal thickening. Compared with psoriasis-like skin lesions in mice, BALB/c mice had higher PAIS scores (P<0.05 or P<0.01), and more significant histopathological changes and epidermal thickening (P<0.05 or P<0.01). After applying imiquimod for 2 days, the relative expressions of IL-23, IL-17A and IL-17F mRNA in the two mice were significantly increased, and all showed a dynamic change from high to low. Among them, the expression of BALB/c mice The peak appeared at 2d after drug application, and the peak expression in C57BL/6 mice appeared at 4d after drug application.

  Conclusion: Imiquimod can induce human psoriasis-like skin lesions in BALB/c and C57BL/6 mice, and BALB/c mice have more typical psoriatic-like skin lesions, which may be more suitable for human psoriasis Studies have shown that the activation of the IL-23/IL-17 axis is one of the important inducing factors for the appearance of skin lesions.