ABSTRACT
ObjectiveTo investigate the effect and potential mechanism of Dihuangyin on 2， 4-dinitrochlorobenzene （DNCB） -induced model mice with atopic dermatitis （AD）. MethodA mouse model with AD was established by repeatedly stimulating the back skin of mice with DNCB. After successful modeling， the mice were randomly divided into model group， Runzao group （0.78 g·kg-1）， and high， medium， and low dose （40.30， 20.15， and 10.08 g·kg-1） groups of Dihuangyin， with 12 mice in each group， and the blank group consisted of 12 mice， 72 in total. The administration groups were given the corresponding liquid by dose， and the blank group and model group were given the same dose of pure water by intragastric administration， once a day. The skin lesions and scratching times of mice were observed after continuous administration for two weeks. The back skin lesions of mice were stained with hematoxylin-eosin （HE） and toluidine blue to observe the pathology. The contents of serum immunoglobulin E （IgE）， interleukin-4 （IL-4）， interleukin-6 （IL-6）， and interferon-γ （IFN-γ） were detected by enzyme-linked immunosorbent assay （ELISA）. The mRNA expression levels of IFN-γ， IL-4， IL-6， Janus kinase 1 （JAK1）， and transcriptional activator 3 （STAT3） in skin lesion tissue were detected by Real-time fluorescence quantitative polymerase chain reaction （Real-time PCR）. The expressions of JAK1， phosphorylation（p）-JAK1， STAT3， and p-STAT3 proteins in skin lesion tissue were detected by Western blot. ResultCompared with the blank group， the back skin of the model group showed large-scale scab， dryness， erosion， hypertrophy with scratching， epidermal hyperplasia with hyperkeratosis and parakeratosis， hyperacanthosis with edema， and a large number of mast cell infiltration in the dermis， some of which were degranulated. The contents of IgE， IL-4， IL-6， and IFN-γ in the serum of mice were significantly increased （P<0.01）， and the protein expression levels of p-JAK1， STAT3， and p-STAT3 and mRNA expressions of IL-4， IL-6， IFN-γ， JAK1， and STAT3 in skin lesion tissue were significantly increased （P<0.01）. Compared with the model group， only a small amount of dryness and desquamation were observed in the back skin of mice in each administration group， and cell edema was reduced. The inflammatory infiltration was significantly reduced， and the number of mast cell infiltration was significantly decreased. The serum IgE， IL-4， IL-6， and IFN-γ of mice were decreased to varying degrees （P<0.05， P<0.01）. The protein expression levels of p-JAK1， STAT3， and p-STAT3 and mRNA expressions of IL-4， IL-6， IFN-γ， JAK1， and STAT3 in skin lesion tissue were significantly decreased， and the effect of high dose group of Dihuangyin was the best （P<0.01）. ConclusionDihuangyin can improve skin lesions and pruritus in mice with AD， and its mechanism may be related to the effective regulation of cytokines on the helper T cells （Th1）/Th2 axis by interfering with the JAK1/STAT3 signaling pathway and affecting skin barrier function.