Olopatadine hydrochloride suppresses the rebound phenomenon after discontinuation of treatment with a topical steroid in mice with chronic contact hypersensitivity

BACKGROUND: Olopatadine hydrochloride (olopatadine; Allelock) is one of the second-generation antihistamines that are treated for allergic disorders such as rhinitis, urticaria and eczema dermatitis. Olopatadine has recently been shown to have inhibitory effects on the chronic contact hypersensitivity induced by repeated application of oxazolone in mice. Although topical steroids have widely been prescribed for atopic dermatitis, a relapse often occurs within several days after discontinuation of their prolonged use. OBJECTIVES: We investigated the possible efficacy of olopatadine against the relapse after discontinuation of prolonged use of topical prednisolone in the Balb/c mice with oxazolone-induced chronic contact hypersensitivity. METHODS: Mice with the chronic contact hypersensitivity induced by repeated application of oxazolone were treated with olopatadine as a sequential therapeutic agent. The effects of olopatadine were quantified by measurements of ear-swelling, and levels of cytokines and histamine in the lesioned ear. Results Topical prednisolone (0.05 mg/ear/day) significantly inhibited the increases in ear swelling and production of IL-1beta, IL-4, IL-18, granulocyte-macrophage colony-stimulating factor (GM-CSF) and histamine. However, after discontinuation of the treatment with topical prednisolone, the inflammation relapsed and the IL-4 level exceeded the control one. The sequential treatment with olopatadine (10 mg/kg/day) after discontinuation of the treatment with topical prednisolone alone, or topical prednisolone with olopatadine, significantly inhibited the increases in ear swelling and levels of IL-1beta, IL-4, IL-18, GM-CSF, nerve growth factor and histamine. CONCLUSIONS: These results indicate that olopatadine is an antihistamine agent having inhibitory activities against the rebound phenomenon following the discontinuation of topical steroid therapy. Olopatadine is thus expected to be a sequential therapeutic agent after discontinuation of the chronic treatment with a topical steroid.     

An obligate role for T-cell receptor alphabeta+ T cells but not T-cell receptor gammadelta+ T cells, B cells, or CD40/CD40L interactions in a mouse model of atopic dermatitis

BACKGROUND: We recently described a murine model of atopic dermatitis (AD) elicited by epicutaneous sensitization with ovalbumin (OVA). The skin lesions in these mice were characterized by a dermal infiltrate consisting of eosinophils and T cells and by increased expression of the TH2 cytokines IL-4 and IL-5. Epicutaneous sensitization induces a rise in the levels of serum total IgE and OVA-specific antibodies, further indicating that it elicits a predominantly TH2 response. OBJECTIVE: This study was undertaken to assess the roles of T cells, B cells, and CD40L-CD40 interactions in AD. METHODS: Mice with targeted gene deletions were sensitized with OVA. Histologic and immunohistochemical examinations, as well as measurements of IL-4 mRNA, were performed on OVA-sensitized skin. Total and antigen-specific serum IgE levels were determined. RESULTS: RAG2(-/-) mice, which lack both T and B cells, did not exhibit cellular infiltration, induction of dermal IL-4 mRNA, or elevation of serum IgE after OVA sensitization; all of these features were present in B-cell-deficient IgH(-/-) mice. T-cell receptor alpha(-/-) mice did not display cellular infiltration, IL-4 mRNA expression, or increased IgE levels after OVA sensitization, but these responses were elicited in T-cell receptor delta(-/-) mice after sensitization. Absence of CD40 had no effect on these responses. CONCLUSION: These results suggest that alphabeta T cells, but not gammadelta T cells, B cells, or CD40L-CD40 interactions, are critical for skin inflammation and the TH2 response in AD.     

Selective enhancement of production of IgE, IgG4, and Th2-cell cytokine during the rebound phenomenon in atopic dermatitis and prevention by suplatast tosilate.

BACKGROUND: Atopic dermatitis is a chronic inflammatory skin disease, which is commonly treated with topical steroids. It is, however, associated with rebound after therapy has been discontinued. OBJECTIVE: This study was designed to elucidate the mechanisms of the rebound phenomenon, and to test the effect of an oral anti-allergic medication, suplatast tosilate, on atopic dermatitis. METHODS: This is a randomized, placebo controlled study. Patients with atopic dermatitis who had been treated with strong steroid ointment (dexamethasone valerate) for several years were divided into two groups. One group (the control group, n = 15) was treated with a non-steroid anti-inflammatory ointment (bufexamac ointment), while the other group (the suplatast tosilate group, n = 17) was treated with the anti-allergic medications, suplatast tosilate and bufexamac ointment. In each group, in vitro production of immunoglobulins and cytokines before and after 2 weeks of treatment was measured. RESULTS: In the control group, 15 of the 15 patients experienced rebound and mean production of IgE, IgG4, IL-4, IL-5, IL-10, and IL-13 was enhanced after 2 weeks. In contrast, only 2 of the 17 patients in the suplatast tosilate group experienced rebound. There was no enhancement of production of immunoglobulins and cytokines after 2 weeks of treatment. CONCLUSION: Enhanced production of the Th2-cell cytokines, which selectively induces IgE and IgG4 production, may be involved in the pathogenesis of the rebound phenomenon, and that suplatast tosilate may prevent the rebound phenomenon by down-regulating the production of these cytokines.     

Mast cells regulate IFN-gamma expression in the skin and circulating IgE levels in allergen-induced skin inflammation.

BACKGROUND: Mast cells are important effector cells in IgE-mediated allergic reactions. They are present in normal skin and increased in skin lesions of patients with atopic dermatitis (AD). OBJECTIVE: We used mice deficient in mast cells (W/W(v)) to assess the role of these cells in a murine model of allergen-induced skin inflammation induced by repeated epicutaneous sensitization with ovalbumin (OVA); the model exhibits many of the characteristics of AD. METHODS: Mice deficient in mast cells were sensitized with OVA. Histologic and immunohistochemical examinations, as well as measurements of IL-4 and IFN-gamma mRNA, were performed on OVA-sensitized skin. Total and antigen-specific serum IgE levels were determined. RESULTS: Infiltration in W/W(v) mice by mononuclear cells, T cells, and eosinophils in OVA-sensitized skin was comparable to that in wild-type (WT) controls. Expression of IL-4 mRNA in sensitized skin sites was similarly increased in WT and W/W(v) mice. However, IFN-gamma mRNA expression was significantly increased in sensitized skin of W/W(v) mice but not in that of WT controls. IL-4 mRNA was readily detectable in unsensitized skin of WT controls but not in that of W/W,(v) mice, whereas expression of IL-12 p40 mRNA was significantly increased in unsensitized skin of W/W(v) mice in comparison with WT controls. Total serum IgE levels were significantly increased after epicutaneous sensitization in W/W(v) mice in comparison with WT controls. CONCLUSION: These results suggest that mast cells regulate IFN-gamma expression in the skin and IgE levels in the circulation in a model of allergen-induced skin inflammation with similarities to AD. This is important, given the role of IFN-gamma in keratinocyte injury in AD and the role of IgE-mediated reactions in exacerbating AD.     

CCL17 transgenic mice show an enhanced Th2-type response to both allergic and non-allergic stimuli

CC chemokine ligand (CCL)17 is implicated in the pathogenesis of atopic dermatitis (AD). To study the effect of CCL17 produced by keratinocytes (KC) during inflammation, we created transgenic (Tg) mice in which CCL17 is overexpressed in KC. Th2-type contact hypersensitivity (CHS) was enhanced and Th1-type CHS was suppressed in these mice. Increased numbers of CC chemokine receptor (CCR)4(+) cells and mast cells infiltrated in Tg mice. Levels of IL-4 mRNA were higher and those of IFN-gamma mRNA were lower in both acute and chronic CHS. Higher levels of serum IgE were observed after CHS. Numbers of CCR4(+) cells among PBMC were increased in Tg mice challenged acutely on the trunk. Chronic irritation with croton oil induced dermatitis and an elevation of serum IgE levels. Tg mice showed enhanced ear swelling after tape stripping. CCL17 was thought to modify the inflammation caused by sensitizing reagents as well as irritant reagents by attracting CCR4(+) cells into the lesional skin and creating a Th2-dominant condition. AD-like conditions such as increased number of mast cells and elevated levels of serum IgE were observed. Thus, CCL17 may participate in the pathogenesis of skin diseases such as AD by regulating both allergic and irritant inflammation.     

Murine model of atopic dermatitis associated with food hypersensitivity

BACKGROUND: Atopic dermatitis (AD) is an eczematous skin eruption that generally begins in early infancy and affects up to 12% of the population. The cause of this disorder is not fully understood, although it is frequently the first sign of atopic disease and is characterized by an elevated serum IgE level, eosinophilia, and histologic tissue changes characterized early by spongiosis and a CD4(+) T(H)2 cellular infiltrate. Hypersensitivity to foods has been implicated as one causative factor in up to 40% of children with moderate-to-severe AD. OBJECTIVE: The purpose of this study was to establish a murine model of food-induced AD. METHODS: Female C3H/HeJ mice were sensitized orally to cow's milk or peanut with a cholera toxin adjuvant and then subjected to low-grade allergen exposure. Histologic examination of skin lesions, allergen-specific serum Ig levels, and allergen-induced T-cell proliferation and cytokine production were examined. RESULTS: An eczematous eruption developed in approximately one third of mice after low-grade exposure to milk or peanut proteins. Peripheral blood eosinophilia and elevated serum IgE levels were noted. Histologic examination of the lesional skin revealed spongiosis and a cellular infiltrate consisting of CD4(+) lymphocytes, eosinophils, and mast cells. IL-5 and IL-13 mRNA expression was elevated only in the skin of mice with the eczematous eruption. Treatment of the eruption with topical corticosteroids led to decreased pruritus and resolution of the cutaneous eruption. CONCLUSION: This eczematous eruption resembles AD in human subjects and should provide a useful model for studying immunopathogenic mechanisms of food hypersensitivity in AD.     

High-Intensity Swimming Exercise Increases Dust Mite Extract and 1-Chloro-2,4-Dinitrobenzene-Derived Atopic Dermatitis in BALB/c Mice

The aim of this study was to investigate the effect of high-intensity swimming exercise (HISE) on atopic dermatitis (AD). For the study, we established an AD model in BALB/c mice by repeated local exposure of house dust mite extract (Dermatophagoides farinae extract, DFE) and 1-chloro-2,4-dinitrobenzene (CDNB) to the ears. After HISE for 4 weeks, epidermal thickness, mast cell infiltration, serum immunoglobulin E (IgE), and histamine were measured. In addition, the gene expression of interleukin (IL)-5 and IL-31 in the ears was assayed. HISE increased DFE/CDNB-induced AD symptoms based on ear thickness, histopathological analysis, and serum IgE level. Moreover, HISE exercise stimulated mast cell infiltration into the ear, elevation of serum histamine, and DFE/CDNB-induced expression of IL-5 and IL-31 in the ears in the AD model. Taken together, our results indicate the possibility that HISE-induced stress gives rise to AD symptoms through the stimulation of IgE level by increasing IL-5 and IL-31 production.     

Effects of TNCB sensitization in DS-Nh mice, serving as a model of atopic dermatitis, in comparison with NC/Nga mice

BACKGROUND: It has been predicted that a type-1 and type-2 helper T cell (Th1/Th2) imbalance exists in atopic dermatitis (AD). In DS-Nh mice, an AD mouse model, Staphylococcus aureus increases on the skin surface. OBJECTIVE: To investigate whether the Th1-dominant response has an influence on the development of AD, we induced chronic allergic hypersensitivity with 2,4,6-trinitrochlorobenzene (TNCB ) in two AD mouse models: NC/Nga mice and DS-Nh mice. Th1 and Th2 cytokine production of splenocytes was assessed under stimulation with staphylococcal enterotoxin B (SEB) which induces a Th1 response in DS-Nh mice with or without TNCB sensitization. METHODS: We examined clinical skin changes, transepidermal water loss (TEWL), the number of S. aureus on the skin and the serum IgE levels in these mice treated repeatedly with TNCB under conventional conditions (free of fur mites). The splenocytes of DS-Nh mice were cultured with SEB and the cytokine levels in the supernatants were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: Significant skin changes were observed on the skin even where TNCB was not applied in both mice treated with TNCB. Increases in S. aureus on the skin and serum IgE levels were detected in DS-Nh mice, but not in NC/Nga mice. In DS-Nh mice, IFN-gamma and IL-13 production of splenocytes increased in the mice treated with TNCB. CONCLUSION: These results suggest that there might be a different mechanism of dermatitis induction between NC/Nga and DS-Nh mice. Th1 responses might play an important role in the development of dermatitis and increase in serum IgE levels in DS-Nh mice through an increase in IL-13 production.     

Interleukin-18 is elevated in the sera from patients with atopic dermatitis and from atopic dermatitis model mice, NC/Nga

BACKGROUND: Several lines of in vitro and in vivo studies have demonstrated that interleukin-18 (IL-18) shows both antiallergic and allergy-promoting activities. But its expression in allergic diseases remains unknown. METHODS: Serum IL-18 levels from atopic dermatitis (AD) model mice, NC/Nga and control mice and from patients with AD and healthy volunteers were measured by ELISA. The relationship between IL-18 levels and serum IgE levels or clinical severity was also examined. RESULTS: Serum IL-18 levels from NC/Nga mice were significantly increased compared to those from control mice. The elevation of IL-18 in the sera was observed prior to the onset and during the development of dermatitis in NC/Nga mice. In addition, IL-18 levels in the sera from patients with AD were significantly (p < 0.05) elevated compared to those from healthy volunteers. However, serum IL-18 levels tended to correlate negatively with serum IgE levels in patients with AD and NC/Nga mice. CONCLUSION: IL-18 is overexpressed in AD.     

Effect of Chrysanthemi borealis flos on atopic dermatitis induced by 1-chloro 2,4-dinitrobenzene in NC/Nga mouse

The flower of Chrysanthemum boreale has traditionally been used for treatment of various inflammatory disease including atopic dermatitis (AD). However, its action on AD is unclear. Therefore, we investigated the effect of CB on AD using NC/Nga mice as an AD model. The effect of CB on 1-Chloro-2,4-dinitrobenzene (DNCB) induced NC/Nga mice was evaluated by examining skin symptom severity, itching behavior, ear thickness, levels of serum Immunoglobulin E (IgE), tumor necrosis factor-α (TNF-α), and interleukin-4 (IL-4), skin histology. The CB significantly reduced the total clinical severity score, itching behavior, ear thickness and the level of serum IgE in AD mouse model. CB not only decreased TNF-α but also IL-4. These results suggest that CB may be a potential therapeutic modality for AD.     

Effect of Chrysanthemi borealis flos on atopic dermatitis induced by 1-chloro 2,4-dinitrobenzene in NC/Nga mouse

The flower of Chrysanthemum boreale has traditionally been used for treatment of various inflammatory disease including atopic dermatitis (AD). However, its action on AD is unclear. Therefore, we investigated the effect of CB on AD using NC/Nga mice as an AD model. The effect of CB on 1-Chloro-2,4-dinitrobenzene (DNCB) induced NC/Nga mice was evaluated by examining skin symptom severity, itching behavior, ear thickness, levels of serum Immunoglobulin E (IgE), tumor necrosis factor-α (TNF-α), and interleukin-4 (IL-4), skin histology. The CB significantly reduced the total clinical severity score, itching behavior, ear thickness and the level of serum IgE in AD mouse model. CB not only decreased TNF-α but also IL-4. These results suggest that CB may be a potential therapeutic modality for AD.     

Enhanced expression of B7.2 (CD86) by percutaneous sensitization with house dust mite antigen

House dust mite antigen is a well-known allergen in the pathogenesis of atopic dermatitis (AD), a chronic relapsing inflammatory skin disease. We evaluated the AD model mice sensitized with house dust mite antigen and observed a Th2-dominant immune response. In this experiment, BALB/c mice were sensitized percutaneously with house dust mite antigen three times with 7 days interval after skin barrier disruption. A remarkable infiltration of polymorphonuclear granulocytes and monocytes in the cutis was observed in mice treated with this antigen, high serum IgE levels and IL-4 mRNA expression in local lymph node cells was also observed. CD19(+) B cell numbers overturned to CD4(+) helper T cells. In these mice, there was significant increase of B7.2 (CD86) expression on CD19(+) B cells. These results indicate that house dust mite antigen sensitizes BALB/c mice and skews their Th1/Th2 balance toward Th2.     

Effects of the macrolide antibiotic, midecamycin, on Staphylococcus aureus product-induced Th2 cytokine response in patients with atopic dermatitis.

In the present study, the effects of the macrolide antibiotic, midecamycin (MDM), on the Th2 cytokine response induced by the Staphylococcus aureus products, staphylococcal enterotoxin B (SEB), lipoteichoic acid (LTA), and peptidoglycan (PEG), was investigated in human peripheral blood mononuclear cells (PBMCs) from patients with atopic dermatitis (AD). MDM inhibited SEB-induced mRNA expression of the Th2 cytokines interleukin-4 (IL-4) and IL-5 in PBMCs from patients with AD. Furthermore, MDM also suppressed LTA-induced or PEG-induced IL-5 mRNA expression in these patients. Inhibition of mRNA expression by MDM correlated with the synthesis of cytokines in PBMCs, indicating that MDM controls Th2 cytokine production. In addition, S. aureus strains isolated from skin lesions of patients with AD were particularly susceptible to MDM compared with gentamicin, which is used widely in Japan as an antibiotic ointment combined with steroid for topical application in AD. These results suggest that topical administration of MDM might be beneficial in AD lesions infected with S. aureus.     

Atopic dermatitis-like skin lesions induced by topical application of mite antigens in NC/Nga mice.

BACKGROUND: Atopic dermatitis (AD) is a chronic relapsing inflammation usually observed in patients with an individual or a familial history of atopic diseases, precipitated by environmental factors including mite antigens (Ag). However, the exact etiology of AD is unclear. To further explore the pathogenesis and treatment of AD, a suitable animal model is necessary. In this study, we developed a new animal model of AD induced by mite Ag in NC/Nga mice. METHODS: We injected the extracts of mite Ag intradermally at the ventral side of the ear of SPF NC/Nga mice on days 0, 2, 4, 7, 9, 11, 14 and 16, and measured the clinical symptoms and the ear thickness. On day 18, we collected blood and submandibular lymph nodes (LN) of the immunized ear to perform a histochemical analysis, and to measure the plasma immunoglobulins and cytokines. RESULTS: The NC/Nga mice immunized with mite Ag suffered from AD-like skin lesions including erythema followed by edema, excoriation and scaling. The histological and immunohistochemical examinations of the affected skin showed epidermal hyperplasia with hyperkeratosis, severe infiltration of CD4+ T lymphocytes, eosinophils and macrophages, and degranulation of mast cells. The total plasma IgE level was markedly elevated in mite Ag-treated mice. LN cells of mice immunized with mite Ag synthesized IgE in an Ag-dependent manner and secreted interleukin-4 (IL-4) and IL-5 but not interferon-gamma. CONCLUSIONS: NC/Nga mice treated with mite Ag manifest clinical and immunological aspects similar to patients with AD, suggesting that this model is suitable for exploring the pathogenesis of human AD.     

Influence of respiratory syncytial virus infection on cytokine and inflammatory responses in allergic mice

BACKGROUND: Th2 lymphocyte responses are associated with inflammation and disease during allergic responses. Exposure to particular environmental factors during the expression of allergy could result in more pronounced Th2-like immune responses and more severe disease. One factor might be a respiratory virus infection. OBJECTIVE: The aim of our study was to investigate the influence of respiratory syncytial virus (RSV) infection on the expression of ovalbumin (OVA)-induced allergy in BALB/c mice. METHODS: We determined OVA-specific IgE in serum, cytokine profiles and histopathological lesions in lungs of OVA-allergic mice after RSV infection. RESULTS: OVA sensitization and challenge induced OVA-specific IgE in serum, Th2 cytokine mRNA expression, and mononuclear and eosinophilic inflammation in the lungs. RSV inoculation during the challenge period enhanced OVA-induced IL-4 and IL-5 mRNA expression in lung tissue. RSV further enhanced the OVA-induced hypertrophy of mucous cells and eosinophilic infiltration in lung tissue. Surprisingly, RSV infection decreased Th2 cytokine secretion and eosinophilic influx in bronchoalveolar lavage of OVA-allergic mice. Because inactivated RSV did not influence these responses, replication of RSV appeared essential for the modification of OVA-induced Th2 cytokine expression. RSV did not change OVA-specific IgE levels in serum. Furthermore, the RSV-induced IL-12 mRNA expression in lung tissue of OVA-allergic mice was diminished, but IFN-gamma mRNA expression was not affected. CONCLUSION: RSV infection enhanced particular OVA-induced Th2 cytokine mRNA responses and pulmonary lesions in allergic mice and thus aggravated allergic respiratory disease.     

Percutaneous sensitization with allergens through barrier-disrupted skin elicits a Th2-dominant cytokine response

We investigated whether percutaneous sensitization with different allergens through barrier-disrupted skin regulates the balance of Th1/Th2 cytokine expression. When mice were sensitized with the typical hapten picryl chloride (PiCl) by a single topical application to intact skin, there was an up-regulation in the lymph nodes (LN) of mRNA expression for the Th1 cytokines IL-2 or IFN-γ, and for the Th2 cytokine IL-4. In contrast, sensitization with PiCl after barrier disruption of the skin down-regulated the expression of mRNA for IFN-γ in a tape-stripping number-dependent manner without changing the expression of mRNA for IL-4. When mice were sensitized with house dust mite antigens (MA) by a single topical application to barrier-disrupted abdominal skin, there was a tape-stripping number-dependent up-regulation in the LN of mRNA expression for IL-4 but not for IL-2 or IFN-γ. In the LN, mRNA for the IL-4-inducible immunoglobulins IgE and IgG1, but not for the IFN-γ-inducible IgG2a, were up-regulated after sensitization with MA, while all three immunoglobulin mRNA were augmented after PiCl sensitization through intact skin. Antigenic elicitation by a topical application of PiCl in aural skin of mice sensitized through intact skin consistently increased the expression of mRNA for all three cytokines in the challenged skin, whereas elicitation in mice sensitized through barrier-disrupted skin decreased the expression of mRNA for IL-2 and IFN-γ, but not for IL-4. Antigenic elicitation by subcutaneous injection of MA in aural skin consistently increased the expression of mRNA for IL-4, but not for IL-2 or IFN-γ in the challenged skin. Infiltration of eosinophils in the dermis was more prominent following elicitation with MA in mice sensitized through barrier disruption than with PiCl in mice sensitized through intact skin. These findings suggest that the percutaneous entry of environmental allergens through barrier-disrupted skin is strongly associated with the induction of Th2-dominant immunological responses, as is seen in atopic dermatitis.     

COX-2 inhibition enhances the TH2 immune response to epicutaneous sensitization

BACKGROUND: Mechanical injury to the skin by scratching is an important feature of atopic dermatitis (AD). OBJECTIVE: To investigate the role of COX-2 in allergic skin inflammation elicited by epicutaneous (EC) sensitization via introduction of ovalbumin through shaved tape-stripped skin. METHODS: COX-2 mRNA was measured by quantitative PCR, and COX-2 protein was measured by Western blotting. We investigated the effect of administration of the COX-2 selective inhibitor NS-398 during EC sensitization with ovalbumin in a mouse model of AD characterized by eosinophil skin infiltration, elevated total and antigen specific IgE, and a systemic TH2 response to antigen. We further examined the response of COX-2-deficient mice to EC immunization with ovalbumin. RESULTS: Tape stripping caused a transient increase in skin COX-2 mRNA. In contrast, COX-2 mRNA was not increased after ovalbumin sensitization. Infiltration by eosinophils and expression of IL-4 mRNA in ovalbumin-sensitized skin sites, ovalbumin specific IgE and IgG1 antibody responses, and IL-4 secretion by splenocytes after ovalbumin stimulation were all significantly increased in EC mice that received NS-398. In contrast, ovalbumin specific IgG 2a antibody response and IFN-gamma secretion by splenocytes after ovalbumin stimulation were significantly decreased in these mice. COX-2-deficient mice also exhibited an enhanced systemic TH2 response to EC sensitization. CONCLUSION: These results demonstrate that COX-2 limits the TH2 response to EC sensitization and suggest that COX inhibitors may worsen allergic skin inflammation in patients with AD.