Gancao Nurish-Yin Decoction Ameliorates Imiquimod-Induced Psoriasis-Like Skin Lesions and Inflammation in Mice

Abstract BackgroundPsoriasis is an autoimmune skin disease with a high clinical prevalence, which is often poses treatment difficulties. In this study, we tested whether Gancao nurish-Yin (GNY) decoction is effective for treating mice with imiquimod (IMQ)-induced psoriasis-like skin lesions. MethodsMice were divided into 4 groups including healthy control group, model group (IMQ-induced psoriasis mice), and two psoriasis induced groups of mice treated with GNY-2.5g/kg and GNY-5g/kg given in the drinking water (n = 8/group). Psoriasis area and severity index (PASI) was used to monitor psoriatic symptoms. H&E staining of dermis and baker’s scores were used to evaluate disease severity. Inflammatory cells positive for Gr-1, CD11c, RORγt and TGF-β were counted by using immunohistochemistry or immunofluorescence staining methods. Flow cytometry was used to analyse CD4+CD17+ Th17 cells, and CD25+Foxp3+ Tregs within splenocyte cell population. Relative mRNA expression of IL-6, IL-10, IL-17A, IL-22, IL-23, TNF-ɑ, TGF-β and AMPKɑ1 in the dermis was was semi-quatified using qPCR. ResultsCompared to model group, GNY decoction treated mice, at both the concentrations, improved morphological features, as demonstrated by PASI scores and decreased levels of hyperproliferating keratinocytes. GNY decoction at a higher concentration significantly decreased Gr-1, CD11c, RORγt and TGF-β positive cells in the dermis as well as the differentiated CD4+CD17+ Th17 cells, whereas, CD25+Foxp3+ Tregs were increased in the spleen, mainly with low dose GNY decoction. Furthermore, relative mRNA expression of IL-6, IL-10, IL-17A, IL-22, IL-23, TNF-ɑ, TGF-β and AMPKɑ1 within dermis were elevated in mice from IMQ model group, which were significantly recduced in mice treated with GNY decoction at GNY-5g/kg concentration.ConclusionHere we demonstrate disease ameliorating effects of GNY decoction in IMQ-induced psoriasis-like skin lesions in mice, which could form basis for considering GNY decoction for treatment of psoriasis patients.