Topical Application And Molecular Mechanism Of Phellopterin,the Bioactive Compound From Angelica Dahurica,on Atopic Dermatitis

Atopic dermatitis is a chronic inflammatory skin disease associated with immunity.It is clinically characterized by dryness,erythema and easy recurrence.Patients often have to endure severe itching,which seriously affects people’s quality of life.At present,the treatment of atopic dermatitis is mainly Western medicine,mainly through external glucocorticoids,antihistamines,the use of immunomodulators and other ways of treatment,but the these treatment can only temporarily relieve atopic dermatitis,unable to achieve a radical cure effect,and long-term treatment will be accompanied by many adverse reactions,and these treatments are expensive.Ordinary families can’t afford it.It has become an irresistible trend to develop safe and effective drugs for atopic dermatitis with few side effects and economical applicability.In recent years,traditional Chinese medicine has shown good effect and small adverse reaction in the treatment of atopic dermatitis.Angelica dahurica is a traditional Chinese medicinal material and a medicinal and edible homologous plant stipulated by the National Health Commission of the People’s Republic of China.With anti-inflammatory,antibacterial and anti-tumor effects,it is widely used in many aspects such as drugs,food,health products,beauty and skin care products,and it is relatively safe and reliable.Phellopterin is a natural active ingredient in Angelica dahurica.Existing studies have shown that it has the effect of lowering blood glucose and lipids,but its anti-inflammatory application is relatively rare.Therefore,the purpose of this study was to establish a mouse atopic dermatitis model by inducing mice with MC903 and a cell inflammation model by inducing human keratinocytes with IL-4,so as to explore the application effect and mechanism of phellopterin on atopic dermatitis from both in vitro and in vivo.1.The effect and mechanism of phellopterin extract from Angelica dahurica were studied by constructing a atopic dermatitis-like in vivoMC903 was continuously stimulated in mouse ear tissue for 19 days to construct a somatic neatopic dermatitis model.The induced mouse ear tissue showed rough,dry,thickened,hardened,and chipping symptoms,which were similar to those of human atopic dermatitis,indicating that the model construction was relatively successful and subsequent studies could be conducted.The mice were divided into four groups.One group received a therapeutic gel containing phellopterin(0.5 μg/g,1.5 μg/g,4.5 μg/g)and the another group received a placebo gel without phellopterin.After 10 days of continuous treatment,the above symptoms were relieved to different degrees in the ear tissues of mice in the treatment group,and the therapeutic gel containing 1.5 μg/g of phellopterin had the best effect.Serum and ear tissues of all mice were collected,and the therapeutic effect and mechanism of phellopterin were explored by ELISA,immunohistochemistry,hematoxylin eosin staining,toluidine blue staining and other methods.The results showed that phellopterin could significantly reduce the serum Ig E level of mice,and reduce the infiltration of eosinophilic granular nuclear mast cells.The infiltration of inflammatory factors such as TSLP and IL-33 was reduced,the secretion of STAT3 pathway-related proteins was reduced,and the nuclear translocation of STAT3 protein was inhibited,but the secretion of upstream inflammatory factor IL-4 was not inhibited.These results suggest that phellopterin can effectively treat Mc903-induced atopic dermatitis in mice,possibly by inhibiting downstream targets of IL-4 mediated pathway to achieve anti-inflammatory effects.2.IL-4 induced HaCaT cells to construct inflammatory cell model in vitro to explore the anti-inflammatory effect and mechanism of phellopterinIL-4(50 ng/mL)and different concentrations of phellopterin(0,2,4,8,16 μM)were co-cultured with HaCaT cells for 24 h.The effects of phellopterin on IL-4-induced HaCaT cells were investigated by western blot,real-time PCR,immunofluorescence,transient transfection and other molecular biological methods.The results showed that in the concentration range of 0～16 μM,the phellopterin inhibited the expression of IL-4-induced inflammatory cytokines TSLPmRNA and IL-33 mRNA and protein,inhibited the expression level of pSTAT3 protein,and reduced the nuclear translocation of STAT3 protein in a dose-dependent manner.After STAT3 knockdown,IL-4 could not induce the normal expression of TSLP and IL-33,indicating that IL-4 induced inflammation depends on the STAT3 pathway.