Portulaca oleracea L. extracts alleviate 2,4-dinitrochlorobenzene-induced atopic dermatitis in mice.

Atopic dermatitis (AD) is a common chronic allergic skin disease characterized clinically by severe skin lesions and pruritus. Portulaca oleracea L. (PO) is a resourceful plant with homologous properties in medicine and food. In this study, we used two different methods to extract PO, and compared the therapeutic effects of PO aqueous extract (POAE) and PO ultrasound-assisted ethanol extract (POEE) on 2,4-dinitrochlorobenzene (DNCB)-induced AD mice. The results showed that in POAE and POEE, the extraction rates of polysaccharides were 16.95% and 9.85%, while the extraction rates of total flavonoids were 3.15% and 3.25%, respectively. Compared with AD mice, clinical symptoms such as erythema, edema, dryness and ulceration in the back and left ear were alleviated, and pruritus behavior was reduced after POAE and POEE treatments. The thickness of the skin epidermis was thinned, the density of skin nerve fibers labeled with protein gene product 9.5 (PGP9.5) was decreased, and mast cell infiltration was reduced. There was a decrease in blood lymphocytes, eosinophils and basophils, a significant decrease in spleen index and a noticeable decrease in serum immunoglobulin E (Ig E). POEE significantly reduced the concentration of the skin pruritic factor interleukin (Il)-31. POAE and POEE reduced the concentration of skin histamine (His), down-regulated mRNA expression levels of interferon-γ (Ifnγ), tumor necrosis factor-α (Tnf-α), thymic stromal lymphopoietin (Tslp) and Il-4, with an increase of Filaggrin (Flg) and Loricrin (Lor) in skin lesions. These results suggested that POAE and POEE may inhibit atopic response and alleviate the clinical symptoms of AD by inhibiting the expression of immune cells, inflammatory mediators and cytokines. PO may be a potential effective drug for AD-like diseases.

Preventative Effects of Antioxidants against PM10 on Serum IgE Concentration, Mast Cell Counts, Inflammatory Cytokines, and Keratinocyte Differentiation Markers in DNCB-Induced Atopic Dermatitis Mouse Model.

Particulate matter (PM) can cause oxidative stress, inflammation, and skin aging. We investigated the effects of antioxidants such as dieckol, punicalagin, epigallocatechin gallate (EGCG), resveratrol, and Siegesbeckiae Herba extract (SHE) against PM < 10 µm (PM10) on serum IgE concentration, mast cell counts, inflammatory cytokines, and keratinocyte differentiation markers in a 2,4-Dinitrochlorobenzene (DNCB)-induced atopic dermatitis mouse model. Seven-week-old BALB/c mice were sensitized with 2% DNCB. Atopic dermatitis-like lesions were induced on the mice with 0.2% DNCB. Antioxidants and PM10 were applied to the mice for 4 weeks. PM10 increased the serum IgE concentration and spleen weight in mice, and all antioxidants downregulated these parameters. Histological examination showed an increase in epidermal thickness and mast cell counts in response to PM10, and all antioxidants showed a decrease. PM10 upregulates the expression of inflammatory cytokines, including interleukin (IL)-1ß, IL-4, IL-6, IL-17α, IL-25, IL-31 and thymic stromal lymphopoietin (TSLP) in mice, and all antioxidants inhibited the upregulation of inflammatory cytokines. ELISA showed the same results as real-time PCR. PM10 downregulates the expression of keratinocyte differentiation markers, including loricrin and filaggrin, in mouse keratinocytes and antioxidants prevented the downregulation of the keratinocyte differentiation markers. Conclusively, PM10 aggravated the DNCB-induced mouse model in serum IgE concentration, mast cell counts, inflammatory cytokine, and keratinocyte differentiation markers. In addition, antioxidants modulated changes in the DNCB-induced mouse model caused by PM10.

Ameliorative Effect of Gramine on 2，4-Dinitrochlorobenzene-Induced Atopic Dermatitis in Mice / 中国实验方剂学杂志

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.

Oral Administration of Sargassum horneri Improves the HDM/DNCB-Induced Atopic Dermatitis in NC/Nga Mice.

The present study investigated the protective effects of Sargassum horneri (S. horneri) ethanol extract (SHE) against atopic dermatitis (AD), known as an abnormal immune response in house dust mite (HDM)/2,4-dinitrochlorobenzene (DNCB)-stimulated NC/Nga mice. The oral administration of SHE attenuated the AD symptoms, including the skin dermatitis severity, transepidermal water loss (TEWL), and ear edema in HDM/DNCB-stimulated mice. Moreover, the histological analysis revealed that SHE improved epidermal hyperplasia and hyperkeratosis, and reduced the dermal infiltrations of mast cells and eosinophils. Moreover, SHE downregulated the expression levels of cytokines (interleukin (IL)-6, IL-10, and interferon (IFN)-γ) and chemokines (Regulated on Activation, Normal T Cell Expressed and Secreted (RANTES), Eotaxin, and Thymus and activation-regulated chemokine (TARC)) by decreasing the expression levels of atopic initiators (IL-25 and IL-33) in HDM/DNCB-stimulated skin. The oral administration of SHE decreased the spleen size, reducing expression levels of AD-related cytokines (IL-4, IL-5, IL-6, IL-10, IL-13, IFN-γ, and TARC) by regulating the expressions of Tbx21 (T-bet), GATA Binding Protein 3 (GATA-3), and Signal transducer and activator of transcription 3 (STAT3). Moreover, SHE significantly attenuated the serum immunoglobulin (Ig)G1 and IgG2a levels in HDM/DNCB-stimulated mice. Collectively, these results suggest that S. horneri could be an ingredient of functional food against abnormal immune response.

Phloretin alleviates dinitrochlorobenzene-induced dermatitis in BALB/c mice.

Atopic dermatitis (AD) is a chronic inflammatory disease of the skin that substantially affects a patient's quality of life. While steroids are the most common therapy used to temporally alleviate the symptoms of AD, effective and nontoxic alternatives are urgently needed. In this study, we utilized a natural, plant-derived phenolic compound, phloretin, to treat allergic contact dermatitis (ACD) on the dorsal skin of mice. In addition, the effectiveness of phloretin was evaluated using a mouse model of ACD triggered by 2,4-dinitrochlorobenzene (DNCB). In our experimental setting, phloretin was orally administered to BALB/c mice for 21 consecutive days, and then, the lesions were examined histologically. Our data revealed that phloretin reduced the process of epidermal thickening and decreased the infiltration of mast cells into the lesion regions, subsequently reducing the levels of histamine and the pro-inflammatory cytokines interleukin (IL)-6, IL-4, thymic stromal lymphopoietin (TSLP), interferon-γ (IFN-γ) and IL-17A in the serum. These changes were associated with lower serum levels after phloretin treatment. In addition, we observed that the mitogen-activated protein kinase (MAPK) and NF-κB pathways in the dermal tissues of the phloretin-treated rodents were suppressed compared to those in the AD-like skin regions. Furthermore, phloretin appeared to limit the overproliferation of splenocytes in response to DNCB stimulation, reducing the number of IFN-γ-, IL-4-, and IL-17A-producing CD4+ T cells in the spleen back to their normal ranges. Taken together, we discovered a new therapeutic role of phloretin using a mouse model of DNCB-induced ACD, as shown by the alleviated AD-like symptoms and the reversed immunopathological effects. Therefore, we believe that phloretin has the potential to be utilized as an alternative therapeutic agent for treating AD.

Correlating the structure and reactivity of a contact allergen, DNCB, and its analogs to sensitization potential.

We report a study that seeks to find a correlation between the overall sensitization potential quantified by the expression of IL-8 by stimulated monocytes and the chemical structure of a model contact allergen, 2,4-dinitrochlorobenzene (DNCB). We show that structure and reactivity of the chemical compounds play an important role in activation of the monocytes and subsequent inflammation in tissue. However, we observed a non-linear correlation between the rate of reaction and biological activity indicating a required balance of stability and reactivity.

Sclareol attenuates the development of atopic dermatitis induced by 2,4-dinitrochlorobenzene in mice.

Context: Atopic dermatitis is a common chronic inflammatory skin disease affecting up to 20% of children and 1% of adults worldwide. Treatment of atopic dermatitis include corticosteroids and immunosuppressants, such as calcineurin inhibitors and methotrexate. However, these treatments often bring about adverse effects including skin atrophy, osteoporosis, skin cancer, and metabolic syndrome. Objective: In this study, we evaluated the therapeutic effects and mechanisms of sclareol, a natural diterpene, on atopic dermatitis (AD)-like skin lesions induced by 2,4-dinitrochlorobenzene (DNCB) in mice. Materials and methods: To evaluate the effect of sclareol in vivo model, BALB/c mice were repeatedly injected intraperitoneally with sclareol (50 and 100 mg/kg) in 2,4-dinitrochlorobenzene (DNCB)-induced AD-like murine model. Major assays were enzyme-linked immunosorbent assay, histological analysis, flow cytometry, western blot analysis. Results: Intraperitoneal administration of sclareol (50 and 100 mg/kg) significantly attenuated AD-like symptoms, such as serum IgE levels, epidermal/dermal hyperplasia, and the numbers of infiltrated mast cells. In addition, systemic sclareol treatments reduced local pro-inflammatory cytokine concentrations, including IL-6, IL-1b, TNF-a, IL-4, IFN-g, and IL-17A, on AD-like lesions. Furthermore, we demonstrated that sclareol also suppressed T cell activation and the capability of cytokine productions (IFN-g, IL-4 and IL-17A) in response to DNCB stimulation. By examining the skin homogenate, we found that sclareol inhibited the AD-like severity likely through suppressions of both NF-kB translocation and phosphorylation of the MAP kinase pathway. Discussion and conclusions: Cumulatively, our results indicate that sclareol induced anti-inflammatory effects against the atopic dermatitis elicited by DNCB. Thus, sclareol is worth of being further evaluated for its potential therapeutic benefits for the clinical treatment of AD.

Bee Venom Phospholipase A2 Alleviate House Dust Mite-Induced Atopic Dermatitis-Like Skin Lesions by the CD206 Mannose Receptor.

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by highly pruritic, erythematous, and eczematous skin plaques. We previously reported that phospholipase A2 (PLA2) derived from bee venom alleviates AD-like skin lesions induced by 2,4-dinitrochlorobenzene (DNCB) and house dust mite extract (Dermatophagoides farinae extract, DFE) in a murine model. However, the underlying mechanisms of PLA2 action in actopic dermatitis remain unclear. In this study, we showed that PLA2 treatment inhibited epidermal thickness, serum immunoglobulin E (IgE) and cytokine levels, macrophage and mast cell infiltration in the ear of an AD model induced by DFE and DNCB. In contrast, these effects were abrogated in CD206 mannose receptor-deficient mice exposed to DFE and DNCB in the ear. These data suggest that bvPLA2 alleviates atopic skin inflammation via interaction with CD206.

A Novel Model for Human Atopic Dermatitis: Application of Repeated DNCB Patch in BALB/c Mice, in Comparison with NC/Nga Mice / 한국실험동물학회지

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.