Mume Fructus improves imiquimod-induced psoriasis-like dermatitis in mice

[Objective] To investigate the therapeutic effects and potential mechanisms of Mume Fructus on imiquimod (IMQ)-induced psoriasis-like dermatitis in mice. [Methods] Thirty-six male BALB/c mice were randomly divided into six groups: i.e, the normal group, model group, dexamethasone-treated group, and Mume Fructus at low-dose, medium-dose, and high-dose groups. Mice, except those in the normal and model groups, were given dexamethasone at a daily dose of 5 mg/kg, or Mume Fructus at a daily dose of 0.3, 0.6, or 1.2 g/kg, respectively, via gavage. The normal and model groups were given water via gavage. Except for the normal group, the other groups were treated topically with IMQ cream to the shaved dorsal area once daily from day 4 to day 7 to induce psoriasis-like dermatitis. During the induction of dermatitis, changes in body weight, psoriasis area and severity index (PASI) scores, and transepidermal water loss rates (TEWL) on the dorsal skin were measured. Hematoxylin-Eosin (HE) staining was used to observe the pathological changes in the skin lesion, and immunohistochemistry was performed to detect the expression of CD3 in the skin lesion. The expression levels of mRNA for IL-1β, IL-6, TNF-α, LOR, and IVL were detected by qRT-PCR. [Results] Compared with the model group, Mume Fructus improved the erythema, scaling, and inflammatory infiltration. Meanwhile, the PASI scores, TEWL, and epidermal thickness were significantly reduced. Immunohistochemistry indicated that Mume Fructus inhibited CD3 expression and reduced T-cell infiltration in the dermis. Moreover, Mume Fructus significantly lowered the expression levels of mRNA for IL-1β (P<0.05 vs. the model group for all doses), IL-6 (P<0.01 vs. model group for low- and medium-doses), and TNF-α (P<0.01 vs. model group for medium and high doses), while increasing the expression levels of mRNA for LOR (P<0.001 vs. model group for medium-dose) and IVL (P<0.05 vs. model group for medium-dose). [Conclusion] Mume Fructus ameliorates imiquimod-induced psoriasis-like dermatitis, inhibits expression of inflammatory factors, and protects the skin barrier in mice.