Effect of Total Glucosides of Paeony on Imiquimod-Induced Psoriatic Skin Lesions by Regulating VEGF

PURPOSE: The purpose of this study was to use a murine model of psoriasis to examine the effect of total glycosides of paeony (TGP) on psoriatic skin lesions and on the expression of vascular endothelial growth factor (VEGF) in skin lesions and blood. METHODS: A murine model of psoriasis was produced by shaving the backs of the mice and applying 5% imiquimod cream, 50 mg, to the backs of the mice once a day. Mice were killed on day 8, and skin and blood samples were obtained for histopathological examination and analysis of VEGF mRNA expression. RESULTS: By day 8 of the application of imiquimod cream, skin lesions characteristic of psoriasis were evident, and histopathological examination of skin sections showed changes consistent with psoriasis (corneum thickening and parakeratosis, attenuation of the stratum granulosum, thickening of the stratum spinosum, and lengthening of the epidermal ridge). In the treatment group, 7 days of treatment with TGP resulted in resolution of the skin lesions, and histopathological examination showed the epidermis and dermis are approximately normal, without corneum thickening, hyperkeratosis, and parakeratosis. On day 7 of treatment, skin expression of VEGF mRNA was significantly lower in the treatment group than in the group that did not receive treatment (p < 0.05). Blood VEGF mRNA expression was not different between the groups. CONCLUSION: TGP is effective for the treatment of psoriasis and may act by decreasing lesion VEGF mRNA expression.