Acitretin exerted a greater influence on T‐helper (Th)1 and Th17 than on Th2 cells in treatment of psoriasis vulgaris

T‐helper (Th) cells, including Th1, Th2 and Th17 cells, may play an important role in the pathogenesis of psoriasis vulgaris (PV). Acitretin is an effective treatment for PV; however, its influence on Th cells during the treatment of PV is unclear. This study aimed to investigate the influence of acitretin on Th1, Th2 and Th17 cells in PV patients. PV patients (n = 30) received acitretin p.o. (20 mg/day) for 8 weeks. Sera and skin biopsies were obtained before and after treatment. Double‐labeled immunofluorescence was used to analyze T, Th1, Th2 and Th17 cells in skin lesions. Enzyme‐linked immunosorbent assay and western blot were used to analyze the expressions of interferon (IFN)‐γ, interleukin (IL)‐4 and IL‐17 in sera and skin lesions. The expressions of IFN‐γ mRNA, IL‐4 mRNA and IL‐17 mRNA in skin lesions were detected by in situ hybridization. Acitretin decreased the quantity of T, Th1 and Th17 cells in PV lesions, but had no significant influence on Th2 cells. Acitretin also decreased the expression of IFN‐γ and IL‐17 in serum and lesions. The expressions of IFN‐γ mRNA and IL‐17 mRNA decreased significantly after 8 weeks of therapy. However, acitretin had no significant influence on the expression of IL‐4 protein and mRNA. Acitretin can reverse Th1 and Th17 preponderance in PV patients to some degree. This may be due to the mechanism of acitretin on PV; however, Th2 cells were not affected by acitretin treatment.     

Time‐dependent progression from the acute to chronic phases in atopic dermatitis induced by epicutaneous allergen stimulation in NC/Nga mice

Atopic dermatitis (AD) is a complicated skin condition influenced by genetic background and environmental factors. In this study, we applied Dermatophagoides farinae body extract (DfE) to the barrier‐disrupted skin of NC/Nga mice twice a week for 8 weeks to identify the clinical and immunological factors in AD progression. Repeated application of the DfE to the skin of NC/Nga mice showed the similar consequences for the natural course of progression in human AD, histologically and immunologically. We confirmed that the AD‐like skin lesions in NC/Nga mice did not last for the whole period of our experiment in spite of repeated topical applications of DfE twice a week. Topical DfE stimulation increased the skin mRNA expressions of Th1‐, Th2‐ and Th17‐related cytokines in the acute phase. The expression patterns of IL‐4 and IL‐13 in splenic T cells and skin lesions were consistent with the time course alterations of clinical features of AD‐like skin symptoms. We also showed that there was a remission phase either just before or right after the chronic phase in this experimental model. Interestingly, splenic T‐cell‐derived IL‐5 expression began to increase in the chronic phase, while skin‐derived IL‐5 mRNA expression increased in the acute phase. In conclusion, our results suggest that we should pay attention to the characteristics of each stage of AD progression and choose a suitable corresponding stage of animal model not only to elucidate the pathogenesis of AD but also to develop and evaluate therapeutic drugs for AD.     

Heparinoid suppresses Der p‐induced IL‐1β production by inhibiting ERK and p38 MAPK pathways in keratinocytes

Epidermal keratinocytes initiate skin inflammation by activating immune cells. The skin barrier is disrupted in atopic dermatitis (AD) and epidermal keratinocytes can be exposed to environmental stimuli, such as house dust mite (HDM) allergens. We showed previously that HDM allergens activate the NLRP3 inflammasome of keratinocytes, thereby releasing pro‐inflammatory cytokines. Heparinoid is an effective moisturizer for atopic dry skin. However, a recent report showed that heparinoid treatment can improve inflammation of lichen planus. Therefore, we hypothesized that it acts on epidermal keratinocytes not only as a moisturizer, but also as a suppressant of the triggers of skin inflammation. We found that HDM allergen‐induced interleukin (IL)‐1β release from keratinocytes was inhibited significantly by heparinoid pretreatment without affecting cell viability. However, heparinoid did not affect caspase‐1 release, suggesting that heparinoid did not affect HDM allergen‐induced inflammasome activation. Heparinoid treatment not only decreased intracellular levels of pro‐IL‐1β, but also suppressed IL‐1β messenger RNA (mRNA) expression in keratinocytes. Among the intracellular signalling pathways, the activation of extracellular signal‐regulated kinase and p38 pathways, which are required for IL‐1β expression in keratinocytes, was inhibited by heparinoid treatment. The inhibitory effect of heparinoid on IL‐1β mRNA expression was also confirmed with living skin equivalents. Our results demonstrated that heparinoid suppresses the initiation of keratinocyte‐mediated skin inflammation.     

Modulation of HMGB1 translocation and RAGE/NFκB cascade by quercetin treatment mitigates atopic dermatitis in NC/Nga transgenic mice

Quercetin, glycosylated form of flavonoid compound, has potent antioxidant and anti‐inflammatory properties. In this study, we have investigated the effects of quercetin on skin lesion, high‐mobility group box (HMGB)1 cascade signalling and inflammation in atopic dermatitis (AD) mouse model. AD‐like lesion was induced by the application of house dust mite extract to the dorsal skin of NC/Nga transgenic mouse. After AD induction, quercetin (50 mg/kg, p.o) was administered daily for 2 weeks. We evaluated dermatitis severity, histopathological changes and changes in protein expression by Western blotting for HMGB1, receptor for advanced glycation end products (RAGE), toll‐like receptor (TLR)4, nuclear factor (NF)κB, nuclear factor erythroid‐2‐related factor (Nrf)2, kelch‐like ECH‐associated protein (Keap)1, extracellular signal‐regulated kinase (ERK)1/2, cyclooxygenase (COX)2, tumor necrosis factor (TNF)α, interleukin (IL)‐1β, IL‐2Rα and other inflammatory markers in the skin of AD mice. In addition, serum levels of T helper (Th) cytokines (interferon (IFN)γ, IL‐4) were measured by enzyme‐linked immunosorbent assay. Quercetin treatment attenuated the development of AD‐like skin lesions. Histological analysis showed that quercetin inhibited hyperkeratosis, parakeratosis, acanthosis, mast cells and infiltration of inflammatory cells. Furthermore, quercetin treatment downregulated cytoplasmic HMGB1, RAGE, nuclear p‐NFκB, p‐ERK1/2, COX2, TNFα, IL‐1β, IL‐2Rα, IFNγ and IL‐4 and upregulated nuclear Nrf2. Our data demonstrated that the HMGB1/RAGE/NFκB signalling might play an important role in skin inflammation, and quercetin treatment could be a promising agent for AD by modulating the HMGB1/RAGE/NFκB signalling and induction of Nrf2 protein.     

The crucial role of IL‐22 and its receptor in thymus and activation regulated chemokine production and T‐cell migration by house dust mite extract

House dust mite (HDM) is known as one of the factors that causes atopic dermatitis (AD). Interleukin (IL)‐22 and thymus and activation regulated chemokine (TARC) are related to skin inflammatory disease and highly expressed in AD lesions. However, the effects of HDM on IL‐22 production in T cells and on TARC production and IL‐22Rα receptor expression in keratinocytes are unknown. To identify the role of HDM in keratinocytes and T cells, we investigated IL‐22Rα expression and TARC production in the human keratinocyte cell line HaCaT and IL‐22 production in T cells treated with HDM extract as well as their roles in HDM‐induced skin inflammation. HDM extract not only increased IL‐22Rα expression and TARC production in HaCaT but also enhanced IL‐22, tumor necrosis factor (TNF)‐α and interferon (IFN)‐γ production in T cells. The HDM extract‐induced IL‐22 from T cells significantly increased the production of IL‐1α, IL‐6 and TARC in HaCaT cells. In addition, we found that TARC produced in HDM extract‐treated HaCaT induced T‐cell recruitment. These results suggest that there is a direct involvement of HDM extract‐induced IL‐22 in TARC production and T‐cell migration. Taken together, TARC production in HaCaT through the interaction between IL‐22 and IL‐22Rα facilitates T‐cell migration. These data show one of the reasons for inflammation in the skin lesions of AD patients.     

DAMP molecules S100A9 and S100A8 activated by IL‐17A and house‐dust mites are increased in atopic dermatitis

S100A9 and S100A8 are called damage‐associated molecular pattern (DAMP) molecules because of their pro‐inflammatory properties. Few studies have evaluated S100A9 and S100A8 function as DAMP molecules in atopic dermatitis (AD). We investigated how house‐dust mites affect S100A9 and S100A8 expression in Th2 cytokine‐ and Th17 cytokine‐treated keratinocytes, and how secretion of these molecules affects keratinocyte‐derived cytokines. Finally, we evaluated expression of these DAMP molecules in AD patients. S100A9 expression and S100A8 expression were strongly induced in IL‐17A‐ and Dermatophagoides (D.) farinae‐treated keratinocytes, respectively. Furthermore, co‐treatment with D. farinae and IL‐17A strongly increased expression of S100A9 and S100A8 compared with D. farinae‐Th2 cytokine co‐treatment. The IL‐33 mRNA level increased in a dose‐dependent manner in S100A9‐treated keratinocytes, but TSLP expression did not change. S100A8/A9 levels were also higher in the lesional skin and serum of AD patients, and correlated with disease severity. Taken together, S100A9 and S100A8 may be involved in inducing DAMP‐mediated inflammation in AD triggered by IL‐17A and house‐dust mites.     

Acidification of stratum corneum prevents the progression from atopic dermatitis to respiratory allergy

The presence of congenitally impaired skin barrier followed by atopic dermatitis (AD) is an initial step in the atopic march. The maintenance of acidic pH in the stratum corneum (SC) has been suggested as a therapeutic or preventive strategy for barrier impairment caused by skin inflammation. To determine whether an AD murine model, flaky tail mice, with inherited filaggrin deficiency could develop airway inflammation by repeated topical application followed by nasal inhalation of house dust mite (HDM) antigen (defined as a novel “atopic march animal model”), and whether maintenance of an acidic SC environment by continuous application of acidic cream could interrupt the following atopic march. During the course of HDM treatment, acidic cream (pH2.8) or neutral cream (pH7.4) was applied to flaky tail mice twice daily. Repeated applications and inhalations of HDM to flaky tail mice induced AD skin lesions followed by respiratory allergies. Maintenance of SC acidity inhibited the occurrence of respiratory allergic inflammation as well as AD‐like skin lesions. Collectively, a novel atopic march model could be developed by repeated epicutaneous and nasal applications of HDM to flaky tail mice, and that the acidification of SC could prevent the atopic march from AD to respiratory allergy.     

Increased interleukin‐36γ expression in skin and sera of patients with atopic dermatitis and mycosis fungoides/Sézary syndrome

Interleukin (IL)‐36γ is expressed by keratinocytes and functions as a key initiator of inflammation in the skin. IL‐36γ expression is enhanced by tumor necrosis factor‐α and IL‐17A, having a strong association with psoriasis. In this study, we examined the role of IL‐36γ in atopic dermatitis (AD) and mycosis fungoides (MF)/Sézary syndrome (SS). Serum levels of IL‐36γ in AD patients and MF/SS patients were elevated compared with those of healthy controls. Importantly, serum IL‐36γ levels in AD patients positively correlated with Eczema Area and Severity Index and those of MF/SS patients positively correlated with serum soluble IL‐2 receptor levels. IL‐36γ mRNA levels in AD skin and MF/SS skin were significantly higher than those of normal skin. IL‐36γ mRNA levels in MF/SS skin positively correlated with IL‐17A mRNA levels. Immunohistochemical staining revealed that IL‐36γ was highly expressed in keratinocytes in lesional skin of AD and MF/SS. Taken together, our study demonstrated that IL‐36γ expression was increased in sera and skin of patients with AD and MF/SS as was reported in psoriatic patients.     

Insight into newly discovered innate immune modulation in atopic dermatitis

Atopic dermatitis (AD) is a highly pruritic, chronic relapsing inflammatory skin disease characterized by innate and adaptive immune reactions. In AD, innate immune mechanisms such as pattern recognition receptors and antimicrobial peptides have been investigated in detail, but recently, epidermis‐derived cytokines, namely thymic stromal lymphopoietin (TSLP), IL‐25 and IL‐33, were shown to participate in innate immune reactions independently of adaptive immunity. In addition to conventional innate cells, such as mast cells, basophils and eosinophils, Th2 cytokine‐producing invariant natural killer T (iNKT) cells, innate lymphoid cells (ILCs) and Th17/Th22 cytokine‐producing innate cells – iNKT cells and natural killer (NK)‐like cells – can participate in innate immune modulation in AD. Accordingly, early control of innate immune responses in AD before activation of adaptive immune responses by conventional T and B cells that perpetuate chronic skin inflammation may adequately alleviate acute exacerbations of AD. Therefore, we hypothesized that select immune modulators targeting the innate immune response could potentially be used for individualized treatment of AD.     

Mechanism of pathogenesis of imiquimod‐induced skin inflammation in the mouse: A role for interferon‐alpha in dendritic cell activation by imiquimod

Topical application of imiquimod (IMQ), a Toll‐like receptor (TLR)7 ligand, can induce and exacerbate psoriasis, a chronic inflammatory skin disorder. In a mouse model of IMQ‐induced psoriasis‐like skin inflammation, T‐helper (Th)17 cells and interleukin (IL)‐17/IL‐22‐producing γδ‐T cells have been shown to play a pivotal role. However, the mechanisms of induction of the Th17 pathway and development of psoriasis‐like skin inflammation by IMQ treatment remain unclear. In this study, we investigated pathogenic mechanisms of IMQ‐induced psoriasis‐like skin inflammation in mice. We first confirmed that, together with an increase in IL‐17 and IL‐22 production, application of IMQ to mouse skin induced the expression of cytokines required for activation of the Th17 pathway, and pro‐inflammatory mediators involved in the pathology of psoriasis. Analysis of Tlr7^?/? mice demonstrated that most of the in vivo effects of IMQ were mediated via TLR7. In an in vitro study using plasmacytoid dendritic cells (DCs), IMQ induced production of interferon (IFN)‐α, IL‐23, IL‐6 and tumor necrosis factor (TNF)‐α. Furthermore, when we analyzed in vitro‐generated bone marrow‐derived DCs with features similar to TNF‐α and inducible nitric oxide synthase (iNOS)‐producing DCs, IL‐23, IL‐6, IL‐1β, TNF‐α and iNOS/NO production was weakly induced by IMQ alone and further enhanced after co‐stimulation with IMQ and IFN‐α. These in vitro effects of IMQ were also mediated via TLR7 and the synergistic effect of IMQ, and IFN‐α was suggested to be caused by upregulation of TLR7 expression by IFN‐α. These results demonstrate part of the mechanism by which the Th17 pathway and psoriasis‐like skin inflammation are induced by IMQ and IFN‐α in a mouse model.     

Lipocalin‐2 exacerbates psoriasiform skin inflammation by augmenting T‐helper 17 response

Lipocalin‐2 (LCN2) is an antimicrobial protein and adipokine associated with insulin resistance, obesity and atherosclerotic disease. Psoriasis is a T‐helper (Th)1/Th17‐mediated, chronic inflammatory dermatosis related to metabolic syndromes and serum LCN2 levels are elevated in psoriatic patients. We examined the in vivo effects of LCN2 on topical imiquimod (IMQ)‐induced psoriasiform skin in BALB/c mice and in vitro on human keratinocytes (KC). Clinically, i.p. injected LCN2 exacerbated erythema and scaling in IMQ‐treated murine skin compared with phosphate‐buffered saline injection alone, and it augmented interleukin (IL)‐17A, IL‐17F, IL‐22, IL‐23p19, IL‐12p40, CCL20, tumor necrosis factor‐α, chemokine (C‐X‐C motif) ligand (CXCL)1, CXCL2, DEFB4, DEFB14, LCN2 and S100A7 mRNA levels of IMQ‐treated murine skin while it did not increase the mRNA levels of interferon‐γ, IL‐12p35 or CXCL10. LCN2 in synergy with IL‐17 increased mRNA levels of CCL20, LCN2 and DEFB4A but not of CXCL10 in human KC in vitro. These results suggest that LCN2 enhances the expression of Th17 cytokines/chemokines and antimicrobial peptides in murine IMQ‐treated psoriatic skin and KC. LCN2 may potentiate the development of psoriasis via the enhancement of Th17‐ and antimicrobial peptide‐mediated inflammation.     

CCL7 contributes to the TNF‐alpha‐dependent inflammation of lesional psoriatic skin

Chemokines are small chemotactic proteins that have a crucial role in leukocyte recruitment into tissue. Targeting these mediators has been suggested as a potential therapeutic option in inflammatory skin diseases such as psoriasis. Using quantitative RT‐PCR, we found CCL7, a chemokine ligand known to interact with multiple C‐C chemokine receptors, to be markedly increased in lesional psoriasis as opposed to atopic dermatitis, lichen planus, non‐lesional psoriatic and normal control skin. Surprisingly, this increase in CCL7 mRNA expression exceeded that of all other chemokines investigated, and keratinocytes and dermal blood endothelial cells were identified as its likely cellular sources. In an imiquimod‐induced psoriasis‐like mouse model, CCL7 had a profound impact on myeloid cell inflammation as well as on the upregulation of key pro‐psoriatic cytokines such as CCL20, IL‐12p40 and IL‐17C, while its blockade led to an increase in the antipsoriatic cytokine IL‐4. In humans receiving the TNF‐α‐blocker infliximab, CCL7 was downregulated in lesional psoriatic skin already within 16 hours after a single intravenous infusion. These data suggest that CCL7 acts as a driver of TNF‐α‐dependent Th1/Th17‐mediated inflammation in lesional psoriatic skin.     

T cell-specific overexpression of interleukin-27 receptor α subunit (WSX-1) prevents spontaneous skin inflammation in MRL/lpr mice

Background Interleukin (IL)‐27 and WSX‐1, the receptor α‐specific subunit, have been shown to play important roles in initiating Th1 responses and in inducing immune modulation, and the immunosuppressive effect of IL‐27 appears to be exerted via suppression of IL‐10 and IL‐17, which may participate in the pathogenesis of human systemic lupus erythematosus (SLE). Objectives To examine the significance of IL‐27/WSX‐1 signalling in spontaneous skin inflammation of MRL/lpr mice, a model for SLE. Methods The severity and development of skin lesions, dermal inflammatory cells and epidermal–dermal depositions in the skin lesions of MRL/lpr mice with CD2‐promoted WSX‐1 overexpression (WSX‐1 Tg mice) and those with globally disrupted WSX‐1 (WSX‐1 KO mice) were examined and compared with those of MRL/lpr mice. Results By 4 months of age, both WSX‐1 KO mice and control MRL/lpr mice developed predominantly similar skin inflammation, while WSX‐1 Tg mice hardly did so, demonstrating that intensifying IL‐27/WSX‐1 signalling on T cells prevents the spontaneous skin inflammation. WSX‐1 KO mice showed Th2‐type skin inflammation as evidenced by the Th2‐prone dermal infiltrating cells and an absence of cutaneous Th1‐type IgG deposition. Interestingly, there were significant IL‐17+ dermal infiltrating cells in both WSX‐1 KO and control MRL/lpr mice, which might potentially contribute to the formation of skin inflammation in these mice. Conclusions These data indicate that IL‐27/WSX‐1 signalling may play a protective role in the development of SLE‐like skin inflammation, and modulating IL‐27/WSX‐1 signalling might be an interesting therapeutic strategy in the treatment of SLE.     

IL‐33 is secreted by psoriatic keratinocytes and induces pro‐inflammatory cytokines via keratinocyte and mast cell activation

IL‐33 is a novel pro‐inflammatory cytokine and ligand for the orphan receptor ST2. Although originally defined as an inducer of Th2‐mediated responses, IL‐33 was recently found to be involved in arthritis, a Th1/Th17‐mediated disease. Here, we assessed the ability of IL‐33 to promote inflammation via mast cells (MCs) and keratinocytes (KCs) activation in psoriasis. IL‐33 resulted elevated in the skin but not in the serum of psoriasis patients. IL‐33 was secreted by psoriasis KCs and HaCaT cells after TNF‐α stimulation. In HMC‐1, TNF‐α, but not IL‐17, could induce a robust increase in IL‐33 expression. In HaCaT cells, TNF‐α was able to induce IL‐6, MCP‐1 and VEGF, and the addition of IL‐33 reinforced these increases. TNF‐α + IL‐33 combination showed similar results in primary KCs and ex vivo skin organ culture. In conclusion, our study suggests that IL‐33 may be involved in psoriasis biology via MCs and KCs.     

Heat-killed bacillus Calmette-Guérin and Mycobacterium kansasii antigen 85B combined vaccination ameliorates dermatitis in a mouse model of atopic dermatitis by inducing regulatory T cells

Background Atopic dermatitis (AD) is a recurrent inflammatory skin disease characterized by dominant T‐helper (Th) 2 cytokine response. Bacillus Calmette–Guérin (BCG) has been used for preventing tuberculosis, and is regarded as a strong Th1 cytokine inducer. Antigen (Ag) 85B is a secretory protein present in Mycobacterium species that induces Th1 cytokine production. Objectives We investigated the effects of combined vaccination of heat‐killed BCG (hkBCG) and Mycobacterium kansasii Ag85B in an AD mouse model. Methods For the AD model, keratin 14 promoter‐derived caspase‐1 overexpressing mice (KCASP1Tg) were used. The mice received a combination therapy of hkBCG at age 3 weeks and Ag85B twice weekly for 11 weeks from the 4th week; Ag85B monotherapy from the 4th week; hkBCG monotherapy at the 3rd week; or control saline. Areas of skin lesions, cytokine mRNA expression and serum interleukin (IL)‐18 and immunoglobulin (Ig) E levels were analysed. Inducible Foxp3+ regulatory T cells (iTreg), IL‐10‐producing T cells (Tr1), and interferon (IFN)‐γ/IL‐4/IL‐17‐producing T cells were evaluated in the spleen. Results Saline‐treated mice and hkBCG monotherapy mice spontaneously developed severe dermatitis. However, combined therapy with hkBCG and Ag85B significantly suppressed the development of skin lesions and mast cell infiltrations. Elevations of the serum IgE and IL‐18 levels were significantly suppressed with combined therapy. Mice treated with hkBCG and Ag85B had a normal number of iTreg in the spleen, and decreased number of both IL‐4‐ and IL‐17‐producing CD4+ T cells. The effect of Ag85B monotherapy was limited. Conclusions Combined vaccination with hkBCG and Ag85B decreases AD skin lesions by inducing regulatory T cells, suggesting that this vaccination is a potent and novel therapeutic strategy for AD.     

Evaluation of antimicrobial peptides and cytokine production in primary keratinocyte cell culture from healthy and atopic beagles

Increased secretion of antimicrobial peptides and cytokines is present in atopic skin. The purpose of this study was to compare the production of β‐defensin (cBD)3‐like, cathelicidin (cCath) and cytokines in atopic and healthy canine keratinocytes. Seven atopic house dust mites (HDMs) sensitive and five healthy age‐matched beagles were used. Keratinocytes were stimulated for 24 h, and the supernatant was collected. A significantly higher production of cBD3‐like was present at baseline in atopic compared with healthy keratinocytes, but cBD3‐like did not increase after stimulation. IL‐17 and lipopolysaccharide increased cBD3‐like in healthy compared with atopic keratinocytes. cCath increased in both groups after stimulation. Atopic keratinocytes exposed to HDM produced more IL‐8 and keratinocyte‐derived chemokine‐like than healthy keratinocytes. Exposure to HDM induced an increased IL‐8 in atopic keratinocytes and a decreased IFN‐γ in healthy keratinocytes. These results may suggest an over sensitization of atopic keratinocytes and a possible impairment of the cutaneous defense against micro‐organisms.     

Effects of β‐carotene on oxazolone‐induced atopic dermatitis in hairless mice

Skin acts as a barrier, which protects internal tissues and promotes moisture retention. Atopic dermatitis (AD) is an inflammatory skin disease associated with a variety of genetic and environmental factors that involve helper T cells. β‐Carotene (provitamin A) exhibits antioxidant activity and activates the immune system. However, it is not clear whether inflammation in AD skin is improved by posttreatment with β‐carotene. In the current study, we investigated the effects of β‐carotene on the skin of hairless mice with oxazolone‐induced inflammation/oedema (Ox‐AD mice). We found that skin inflammation was significantly reduced by oral administration of β‐carotene. In addition, treatment with β‐carotene suppressed protein levels of TNF‐α, IL‐1β and MCP‐1, as well as mRNA expression associated with IL‐1β, IL‐6, IL‐4 and Par‐2 in skin tissues. Furthermore, the mRNA and protein levels of filaggrin, a structural protein in the epidermal stratum corneum, were elevated by β‐carotene administration as compared with Ox‐AD mice. β‐Carotene significantly reduced the activity of proMMP‐9, but not proMMP‐2. These results suggest that in Ox‐AD mice, β‐carotene improves skin inflammation by suppressing the expression of inflammatory factors, promoting filaggrin expression and reducing MMP‐9 activity. β‐Carotene is a potent anti‐inflammatory agent that improves the barrier functions of AD skin.     

Effect of topical application and intraperitoneal injection of oregonin on atopic dermatitis in NC/Nga mice

Please cite this paper as: Effect of topical application and intraperitoneal injection of oregonin on atopic dermatitis in NC/Nga mice. Experimental Dermatology 2010; 19 : e37–e43. Abstract: The diarylheptanoid, oregonin (ORE), which was isolated from the bark of Alnus japonica Steudel that grows natively in Korea, has been known to exert antioxidative, anti‐inflammatory, anti‐cancer and immune response inhibitory effects. The antioxidative effect of ORE was observed on the superoxide and 1,1‐diphenyl‐2‐picrylhydrazyl radical, as well as on the expression of inducible nitric oxide synthase and cyclooxygenase‐2 in lipopolysaccharide‐treated RAW264.7 macrophages. The statistically significant inhibitory action of ORE against production of cytokines induced by bacterial products or by interleukin (IL)‐1β, free radicals and nitrogen species, and a corresponding increase in cellular calcium concentration because of ORE were confirmed in bone marrow and spleen dendritic cells that are known to play important functions in the development and advancement of atopic dermatitis (AD). It was thus expected that ORE would exert a beneficial effect in the treatment of AD. A study on the pharmaceutical benefits of ORE against AD has not yet been conducted in vivo. We therefore used an in vivo AD animal model, namely the NC/Nga mice, and by applying ORE onto the animals through skin application as well as intraperitoneal injection, we attempted to evaluate the benefits of ORE in this system. Evaluation of ORE was conducted by following the SCORE method to score the effect, as well as by measuring the Th2 cytokines IL‐4, IL‐5 and IL‐13 levels from serum and lymphocytes, and IgE and eosinophil levels from serum. Additionally, the expression of mRNA and protein levels was estimated using real‐time polymerase chain reaction and Western blotting analysis. The following categories of clinical evaluation, Th2 cytokines IL‐4, IL‐5 and IL‐13 values, serum IgE levels, serum eosinophil levels, and mRNA and protein expression levels of iNOS and COX‐2, were evaluated from topical application and intraperitoneal injection groups of ORE. The effects of ORE on AD in NC/Nga mice were confirmed as being similar to the positive control group, while a significant difference with the negative control group was observed. The results presented in this report suggest that ORE might be beneficial in the treatment of AD.