Study On The Mechanism Of Xiaoyin Recipe In The Treatment Of Psoriasis By Affecting The Immune Function Of T Lymphocytes

OBJECTIVE:Psoriasis is a common chronic reccurent inflammatory dermatosis without known cure.Xiaoyin Decoction could alleviate the disease severity of psoriasis patients,but the detailed mechanism remains elusive.We established imiquimod-induced psoriasis mouse model,treated with Xiaoyin Decoction and assessed its therapeutic effects.After the intervention of Xiaoyin Decoction,skin histomorphology,immune molecules,T lymphocytes and possible therapeutic targets were examined using histology,immunohistochemistry,flow cytometry and transcriptome sequencing.The result will facilitate in clarifing the role of Xiaoyin Decoction in the treatment of psoriasis and enrich the meaning of“clearing heat and detoxifying,cooling blood and promoting blood circulation”.METHODS:Wild-type C57BL/6 male mice were randomly divided into different groups.Psoriasis-like dermatitis was induced by applying 5%imiquimod cream on mouse back skin or ears.Tripterygium wilfordii polyglycoside was served as positive control.Histomorphological changes and the expressions of CD3 and Ki67 in the skin tissues were detected by HE staining and immunohistochemistry.Single cell suspensions of mouse dermis and skin-draining lymph nodes were acquired.T lymphocyte subsets and their secretion of cytokines were measured by flow cytometry.RNA sequencing of epidermis and dermis were performed after the separation of epidermis and dermis.RESULTS:The skin lesions of psoriasis model mice demonstrated erythema,desquamation and thickened thickness,in accordance with the typical pathological characteristics of psoriasis.High-dose Xiaoyin Decoction not only significantly reduced the severity of psoriasis-like skin inflammation,but also exerted therapeutic effects in immune memory of disease recurrence.Remarkably,the proportion of IL-17~+γδT cells in the psoriasis model group was significantly higher than control group(P<0.001).Compared with psoriasis model group,High-dose Xiaoyin Decoction could alleviate psoriasis-like dermatitis posssibaly through inhibiting the activation of IL-17~+γδT cells.RNA sequencing of psoriatic skin lesions revealed a significant difference in the expression of IL-17rd-related genes between High-dose Xiaoyin Decoction groups and psoriasis model group.CONCLUSION:High-dose Xiaoyin Decoction demonstrated excellent therapeutic effects on imiquimod-induced psoriasis-like dermatitis.The underspining mechanism was probably related to the suppression of IL-17~+γδT cell activation.And,IL-17rd might be a crucial target of Xiaoyin Decoction.