RESUMEN
ObjectiveTo explore the pharmacodynamic effect of gramine on 2，4-dinitrochlorobenzene （DNCB）-induced atopic dermatitis （AD） in mice and its potential mechanism. MethodThe mice were divided into the normal control group， model group， dexamethasone （0.05 g·kg-1） group， and high- and low-dose （0.12，0.06 g·kg-1） gramine groups. Mice in all groups except for the normal control group were stimulated with DNCB， followed by medication 13 d later. The changes in skin lesions were then observed， and the skin thickness， moisture content， and transepidermal water loss （TWEL） in each group were measured. The pathological changes in skin lesions were observed by hematoxylin-eosin （HE） staining， and the effects of drugs on CD4+/CD8+T-cell ratio in the spleen were detected by flow cytometry. The levels of immunoglobulin E （IgE）， interleukin （IL）-4， and IL-6 in serum were detected by enzyme-linked immunosorbent assay （ELISA）， and the changes in serum alanine aminotransferase （ALT）， aspartate aminotransferase （AST）， blood urea nitrogen （BUN）， and creatinine （CRE） by microplate method. The mRNA expression levels of inflammatory cytokines γ-interferon（IFN-γ）， IL-13， IL-17， IL-1β， IL-6， and tumor necrosis factor-α （TNF-α） in skin lesions were assayed by real-time polymerase chain reaction （Real-time PCR）， and the protein expression levels of nuclear transcription factor -κB (NF-κB) and NF-κB inhibitory protein α (IκBα) in skin lesions by Western blot. ResultCompared with the normal control group， the model group showed skin edema， erythema， scab， scratch， and lymphocyte and neutrophil infiltration， decreased skin moisture content， as well as increased skin thickness， TWEL （P<0.01）， spleen index， CD4+/CD8+ T-cell ratio in the spleen （P<0.05）， mRNA expression of IFN-γ， IL-13， IL-17， IL-1β， IL-6， and TNF-α in the skin lesions （P<0.05）， serum contents of IgE， IL-4， and IL-6 （P<0.05）， and protein expression of IκBα and NF-κB in skin lesions （P<0.05）. Compared with the model group， dexamethasone and gramine at different doses alleviated skin erythema， scale， scab， and inflammatory cell infiltration， elevated skin moisture content， inhibited skin thickening and TWEL， and decreased spleen index， CD4+/CD8+T-cell ratio in the spleen， mRNA expression of inflammatory factors in the skin lesions， serum contents of IgE and inflammatory factors， and protein expression of IκBα and NF-κB in skin lesions， especially in the dexamethasone group and the high- dose gramine group（P<0.05，P<0.01）. ConclusionGramine can inhibit the expression of related inflammatory factors and regulate the immune function of AD mice via the IκBα/NF-κB pathway， enabling it become a potential drug for treating AD.
RESUMEN
The various murine models have contributed to the study of human atopic dermatitis (AD). However limitations of the models involve low reproducibility and long time to develop AD. In an attempt to overcome these limitations and establish an atopic dermatitis murine model, we repeated the application of 2, 4-dinitrochlorobenzene (DNCB) patch in NC/Nga and BALB/c mice, which has advantages in reproduction and cost. For the sensitization, a 1 cm2 gauze-attached patch, where 1% or 0.2% DNCB was periodically attached on the back of NC/Nga and BALB/c mice. To estimate how homologous our model was with human atopic dermatitis, clinical, histological and immunological alterations were evaluated. Both strains showed severe atopic dermatitis, increase in subiliac lymph node weight, mast cells, epidermal hyperplasia and serum IgE levels. Though both exhibited a high IL-4/IFN-gamma and IL-4/TNF-beta ratio in the expression of mRNA, the shifting of DNCB-treated BALB/c mice was increased to more than double that of NC/Nga mice. These results suggest that our DNCB patched model using BALB/c mice were more suitable than NC/Nga mice in demonstrating the immune response. We anticipate that our novel model may be successfully used for pathogenesis of atopic dermatitis and assessment of therapeutic approaches.