Influence of Asian Dust Particles on Immune Adjuvant Effects and Airway Inflammation in Asthma Model Mice

Objective

An Asian dust storm (ADS) contains airborne particles that affect conditions such as asthma, but the mechanism of exacerbation is unclear. The objective of this study was to compare immune adjuvant effects and airway inflammation induced by airborne particles collected on ADS days and the original ADS soil (CJ-1 soil) in asthma model mice.

Methods

Airborne particles were collected on ADS days in western Japan. NC/Nga mice were co-sensitized by intranasal instillation with ADS airborne particles and/or Dermatophagoides farinae (Df), and with CJ-1 soil and/or Df for 5 consecutive days. Df-sensitized mice were stimulated with Df challenge intranasally at 7 days after the last Df sensitization. At 24 hours after challenge, serum allergen specific antibody, differential leukocyte count and inflammatory cytokines in bronchoalveolar lavage fluid (BALF) were measured, and airway inflammation was examined histopathologically.

Results

Co-sensitization with ADS airborne particles and Df increased the neutrophil and eosinophil counts in BALF. Augmentation of airway inflammation was also observed in peribronchiolar and perivascular lung areas. Df-specific serum IgE was significantly elevated by ADS airborne particles, but not by CJ-1 soil. Levels of interleukin (IL)-5, IL-13, IL-6, and macrophage inflammatory protein-2 were higher in BALF in mice treated with ADS airborne particles.

Conclusion

These results suggest that substances attached to ADS airborne particles that are not in the original ADS soil may play important roles in immune adjuvant effects and airway inflammation.     

Transiently, paralleled upregulation of arginase and nitric oxide synthase and the effect of both enzymes on the pathology of asthma

Changes in the expression of arginase and their association with nitrosative stress were investigated using an asthmatic model previously established in NC/Nga mice with mite extract. Mite crude extract (100 microg/day) from Dermatophagoides farinae was administered intranasally for 5 consecutive days (day 0-4), and a single challenge was performed on day 11. On day 12, upregulation of the mRNA expression of inducible types of nitric oxide synthase (iNOS) and increases in immunohistochemical staining for iNOS and nitrotyrosine were observed. However, the level of nitrite + nitrate was unchanged. An increase in enzymatic activity, upregulation of mRNA expression, and immunostaining for arginase I was detected in the lung tissue and serum. Moreover, increases in both arginase I and II were revealed by immunoblotting. Goblet cell hyperplasia in bronchial epithelial cells and increasing collagen synthesis around the bronchus were also observed. These results suggested that an increase in arginase may lead to decreased availability of arginine for nitric oxide synthase and may contribute to the remodeling of the lung.     

Effect of Mouse Strain in a Model of Chemical-induced Respiratory Allergy

The inhalation of many types of chemicals is a leading cause of allergic respiratory diseases, and effective protocols are needed for the detection of environmental chemical–related respiratory allergies. In our previous studies, we developed a method for detecting environmental chemical–related respiratory allergens by using a long-term sensitization–challenge protocol involving BALB/c mice. In the current study, we sought to improve our model by characterizing strain-associated differences in respiratory allergic reactions to the well-known chemical respiratory allergen glutaraldehyde (GA). According to our protocol, BALB/c, NC/Nga, C3H/HeN, C57BL/6N, and CBA/J mice were sensitized dermally with GA for 3 weeks and then challenged with intratracheal or inhaled GA at 2 weeks after the last sensitization. The day after the final challenge, all mice were euthanized, and total serum IgE levels were assayed. In addition, immunocyte counts, cytokine production, and chemokine levels in the hilar lymph nodes (LNs) and bronchoalveolar lavage fluids (BALF) were also assessed. In conclusion, BALB/c and NC/Nga mice demonstrated markedly increased IgE reactions. Inflammatory cell counts in BALF were increased in the treated groups of all strains, especially BALB/c, NC/Nga, and CBA/J strains. Cytokine levels in LNs were increased in all treated groups except for C3H/HeN and were particularly high in BALB/c and NC/Nga mice. According to our results, we suggest that BALB/c and NC/Nga are highly susceptible to respiratory allergic responses and therefore are good candidates for use in our model for detecting environmental chemical respiratory allergens.     

Inhibitory Effects of Heartwood Extracts of Broussonetia kazinoki Sieb on the Development of Atopic Dermatitis in NC/Nga Mice

We investigated the effects of a topically applied extract of the heartwood of Broussonetia kazinoki Sieb (B. kazinoki) on atopic dermatitis (AD)-like skin lesions induced by an extract of the house-dust mite Dermatophagoides farina in NC/Nga mice. We found that topically applied B. kazinoki extract suppressed the histological manifestations of AD-like skin lesions, and decreased the levels of plasma immunoglobulin E (IgE) and interleukin-4 (IL-4) in the mice. Moreover, B. kazinoki inhibited the induction of thymus-and-activation-regulated chemokine (TARC/CCL17), macrophage-derived chemokine (MDC/CCL22), and regulated-on-activation-normal T cell-expressed-and-secreted chemokine (RANTES/CCL5) in HaCaT cells activated by tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). In conclusion, our results suggest that B. kazinoki extract has therapeutic advantages in the treatment of AD.     

The allergen-induced airway hyperresponsiveness in a human-mouse chimera model of asthma is T cell and IL-4 and IL-5 dependent

The cellular and molecular mechanisms involved in the airway hyperresponsiveness (AHR) of patients with allergic asthma remain unclear. A role for Th2 inflammatory cells was suggested based on murine asthma models. No direct evidence exists on the role of these cells in human asthma. The development of a mouse-human chimera might be useful, allowing the in vivo study of the components of the human immune system relevant to asthma. We investigated the role of allergen-reactive T lymphocytes in a human-mouse SCID model. SCID mice were reconstituted intratracheally with human PBMC from healthy, nonallergic, nonasthmatic donors and exposed to an aerosol of house dust mite allergen after i.p. injection with Dermatophagoides pteronyssinus I Ag and alum. The donor T lymphocytes had a Th1 cytokine phenotype. The reconstituted and allergen-challenged mice developed AHR to carbachol. The mouse airways and lungs were infiltrated with human T lymphocytes. No eosinophils or increases in human IgE were observed. The intrapulmonary human T lymphocytes demonstrated an increase in intracytoplasmic IL-4 and IL-5 and a decrease in IFN-gamma after exposure to allergen adjuvant. Antagonizing human IL-4/IL-13 or IL-5 resulted in a normalization of the airway responsiveness, despite a sustained intracellular Th2 cytokine production. These results provide evidence that the activated human allergen-reactive Th2 cells producing IL-4 or IL-5 are pivotal in the induction of AHR, whereas no critical role for eosinophils or IgE could be demonstrated. They also demonstrate that human allergen-specific Th1 lymphocytes can be driven to a Th2 phenotype.     

Murine eotaxin-2: a constitutive eosinophil chemokine induced by allergen challenge and IL-4 overexpression

The generation of tissue eosinophilia is governed in part by chemokines; initial investigation has identified three chemokines in the human genome with eosinophil selectivity, referred to as eotaxin-1, -2, and -3. Elucidation of the role of these chemokines is dependent in part upon analysis of murine homologues; however, only one murine homologue, eotaxin-1, has been identified. We now report the characterization of the murine eotaxin-2 cDNA, gene and protein. The eotaxin-2 cDNA contains an open reading frame that encodes for a 119-amino acid protein. The mature protein, which is predicted to contain 93 amino acids, is most homologous to human eotaxin-2 (59.1% identity), but is only 38.9% identical with murine eotaxin-1. Northern blot analysis reveals three predominant mRNA species and highest constitutive expression in the jejunum and spleen. Additionally, allergen challenge in the lung with Aspergillus fumigatus or OVA revealed marked induction of eotaxin-2 mRNA. Furthermore, eotaxin-2 mRNA was strongly induced by both transgenic over-expression of IL-4 in the lung and administration of intranasal IL-4. Analysis of eotaxin-2 mRNA expression in mice transgenic for IL-4 but genetically deficient in STAT-6 revealed that the IL-4-induced expression was STAT-6 dependent. Recombinant eotaxin-2 protein induced dose-dependent chemotactic responses on murine eosinophils at concentrations between 1-1000 ng/ml, whereas no activity was displayed on murine macrophages or neutrophils. Functional analysis of recombinant protein variants revealed a critical role for the amino terminus. Thus, murine eotaxin-2 is a constitutively expressed eosinophil chemokine likely to be involved in homeostatic, allergen-induced, and IL-4-associated immune responses.     

A new synbiotic, Lactobacillus casei subsp. casei together with dextran, reduces murine and human allergic reaction

We studied the development of atopic dermatitis-like skin lesions in NC/Nga mice and the allergic symptoms and blood patterns of healthy volunteers during the cedar (Cryptomeria japonica) pollen season in Japan following oral administration of a new synbiotic, Lactobacillus casei subsp. casei together with dextran. The combination of L. casei subsp. casei and dextran significantly decreased clinical skin severity scores and total immunoglobulin E levels in sera of NC/Nga mice that had developed picryl chloride-induced and Dermatophagoides pteronyssinus crude extract-swabbed atopic dermatitis-like skin lesions. During the most common Japanese cedar pollen season, synbiotic L. casei subsp. casei and dextran in humans led to no significant changes in total nasal and ocular symptom scores, in the levels of cedar pollen-specific immunoglobulin E, interferon-gamma and thymus and activation regulated chemokine or in the number of eosinophils in sera, whereas the placebo group showed a tendency for increased levels of cedar pollen-specific immunoglobulin E, thymus and activation regulated chemokine and number of eosinophils, and a decrease in interferon-gamma levels. Thus, the oral administration of synbiotic L. casei subsp. casei together with dextran appears to be an effective supplement for the prevention and treatment of allergic reactions.     

Oral administration of a hop water extract ameliorates the development of dermatitis induced by the periodical topical application of a mite antigen in atopic dermatitis model NC/Nga mice

We investigated the inhibitory effect of an oral administration of a hop water extract (HWE) on the development of dermatitis by using NC/Nga atopic dermatitis model mice. The induction of allergic dermatitis was conducted by tape-stripping and topical application of a mite antigen (Dermatophagoides farinae) on to the ear once a week for 10 weeks. HWE was orally administered at a dose of 100 or 500 mg/kg. The total immunoglobulin E (IgE) concentration in serum and the ear thickness were periodically examined. Finally, the antigen-specific IgE level in the serum and the production of interleukin (IL)-4, IL-12 and interferon (IFN)-gamma from splenocytes and cervical lymph node cells were measured. The oral administration of HWE significantly inhibited the increase of total IgE production and ear swelling throughout the experimental period. The production of IL-12 was significantly lower in the HWE administered group than in the control group. The results suggest that the intake of HWE may be effective in preventing and alleviating the development of atopic dermatitis-like skin disease.     

Role of interleukin-6 in murine airway responses to ozone

This study sought to examine the role of interleukin-6 (IL-6) in ozone (O(3))-induced airway injury, inflammation, and hyperresponsiveness (AHR). Subacute (72 h) exposure to 0.3 ppm O(3) significantly elevated bronchoalveolar lavage fluid (BALF) protein, neutrophils, and soluble TNF receptors (sTNFR1 and sTNFR2) in wild-type C57BL/6 (IL-6(+/+)) mice; however, all four outcome indicators were significantly reduced in IL-6-deficient (IL-6(-/-)) compared with IL-6(+/+) mice. Acute O(3) exposure (2 ppm for 3 h) increased BALF protein, KC, macrophage inflammatory protein(MIP)-2, eotaxin, sTNFR1, and sTNFR2 in IL-6(+/+) mice. However, MIP-2 and sTNFR2 were not significantly increased following O(3) exposure in IL-6(-/-) mice. Increases in BALF neutrophils induced by O(3) (2 ppm for 3 h) were also significantly reduced in IL-6(-/-) vs. IL-6(+/+) mice. Airway responsiveness to methacholine was measured by whole body plethysmography before and following acute (3 h) or subacute (72 h) exposure to 0.3 ppm O(3). Acute O(3) exposure caused AHR in both groups of mice, but there was no genotype-related difference in the magnitude of O(3)-induced AHR. AHR was absent in mice of either genotype exposed for 72 h. Our results indicate that IL-6 deficiency reduces airway neutrophilia, as well as the levels of BALF sTNFR1 and sTNFR2 following acute high dose and/or subacute low-dose O(3) exposure, but has no effect on O(3)-induced AHR.     

Effect of dendritic cells treated with CpG ODN on atopic dermatitis of Nc/Nga mice

Atopic dermatitis (AD) is a chronic inflammatory skin disease and the pathogenesis of AD is associated with the release of various cytokines/chemokines due to activated Th(2) immune responses. Synthetic oligodeoxynucleotides (ODNs) containing unmethylated CpG dinucleotide in the context of particular base sequence (CpG motifs) are known to have the immunostimulatory activities in mice and to convert from Th(2) to Th(1) immune responses in AD. We aimed to investigate that CpG ODN, especially phosphodiester form, can stimulate the protective immunity in NC/Nga mice with AD. We isolated BMDCs from NC/Nga mice and then, cultured with GM-CSF and IL-4 for 6 days, and treated for 2 days by either phosphorothioate ODN or phosphodiester ODN. CpG ODN-treated DCs resulted in more production of IL-12. When CpG ODN-treated DCs were intravenously injected into the NC/Nga mice, the NC/Nga mice with CpG ODN-treated DCs showed significant improvement of AD symptoms and decrease of IgE level. Histopathologically, the NC/Nga mice skin with CpG ODN-treated DCs showed the decreased IL-4 and TARC expression comparing with non-injected mice. These results may suggest that phosphodiester CpG ODN-treated DCs might function as a potent adjuvant for AD in a mouse model.     

CD8 T cells are essential in the development of respiratory syncytial virus-induced lung eosinophilia and airway hyperresponsiveness

Viral respiratory infections can cause bronchial hyperresponsiveness and exacerbate asthma. In mice, respiratory syncytial virus (RSV) infection results in airway hyperresponsiveness (AHR) and eosinophil influx into the airways. The immune cell requirements for these responses to RSV infection are not well defined. To delineate the role of CD8 T cells in the development of RSV-induced AHR and lung eosinophilia, we tested the ability of mice depleted of CD8 T cells to develop these symptoms of RSV infection. BALB/c mice were depleted of CD8 T cells using anti-CD8 Ab treatment before intranasal administration of infectious RSV. Six days postinfection, airway responsiveness to inhaled methacholine was assessed by barometric body plethysmography, and numbers of lung eosinophils and levels of IFN-gamma, IL-4, and IL-5 in bronchoalveolar lavage fluid were monitored. RSV infection resulted in airway eosinophilia and AHR in control mice, but not in CD8-depleted animals. Further, whereas RSV-infected mice secreted increased amounts of IL-5 into the airways as compared with noninfected controls, no IL-5 was detectable in both bronchoalveolar lavage fluid and culture supernatants from CD8-depleted animals. Treatment of CD8-depleted mice with IL-5 fully restored both lung eosinophilia and AHR. We conclude that CD8 T cells are essential for the influx of eosinophils into the lung and the development of AHR in response to RSV infection.     

Oral Administration of a Hop Water Extract Ameliorates the Development of Dermatitis Induced by the Periodical Topical Application of a Mite Antigen in Atopic Dermatitis Model NC/Nga Mice

We investigated the inhibitory effect of an oral administration of a hop water extract (HWE) on the development of dermatitis by using NC/Nga atopic dermatitis model mice. The induction of allergic dermatitis was conducted by tape-stripping and topical application of a mite antigen (Dermatophagoides farinae) on to the ear once a week for 10 weeks. HWE was orally administered at a dose of 100 or 500 mg/kg. The total immunoglobulin E (IgE) concentration in serum and the ear thickness were periodically examined. Finally, the antigen-specific IgE level in the serum and the production of interleukin (IL)-4, IL-12 and interferon (IFN)-γ from splenocytes and cervical lymph node cells were measured. The oral administration of HWE significantly inhibited the increase of total IgE production and ear swelling throughout the experimental period. The production of IL-12 was significantly lower in the HWE administered group than in the control group. The results suggest that the intake of HWE may be effective in preventing and alleviating the development of atopic dermatitis-like skin disease.     

Integrated signals between IL-13, IL-4, and IL-5 regulate airways hyperreactivity

In this investigation, we have examined the integrated relationship between IL-13, IL-4, and IL-5 for the development of airways hyperreactivity (AHR) in a model of asthma in BALB/c mice. Sensitization and aeroallergen challenge of both wild-type (WT) and IL-13 gene-targeted (IL-13-/-) mice induced allergic disease that was characterized by pulmonary eosinophilia and AHR to beta-methacholine. Although these responses in IL-13-/- mice were heightened compared with WT, they could be reduced to the level in nonallergic mice by the concomitant neutralization of IL-4. Mice in which both IL-4 and IL-13 were depleted displayed a marked reduction in tissue eosinophils, despite the development of a blood eosinophilia. Similar neutralization of IL-4 in WT mice only partially reduced AHR with no effect on tissue eosinophilia. In addition, neutralization of IL-5 in IL-13-/- mice, but not in WT mice, inhibited AHR, suggesting that tissue eosinophilia is linked to the mechanism underlying AHR only in the absence of IL-13. Additionally, mucus hypersecretion was attenuated in IL-13-/- mice, despite the persistence of AHR. Taken together, our data suggest both a modulatory role for IL-13 during sensitization and a proinflammatory role during aeroallergen challenge. The latter process appears redundant with respect to IL-4.     

Rapamycin attenuates airway hyperreactivity, goblet cells, and IgE in experimental allergic asthma

The mammalian target of rapamycin (mTOR) signaling pathway integrates environmental cues, promotes cell growth/differentiation, and regulates immune responses. Although inhibition of mTOR with rapamycin has potent immunosuppressive activity, mixed effects have been reported in OVA-induced models of allergic asthma. We investigated the impact of two rapamycin treatment protocols on the major characteristics of allergic asthma induced by the clinically relevant allergen, house dust mite (HDM). In protocol 1, BALB/c mice were exposed to 10 intranasal HDM doses over a period of 24 d and treated with rapamycin simultaneously during the sensitization/exposure period. In protocol 2, rapamycin was administered after the mice had been sensitized to HDM (i.p. injection) and prior to initiation of two intranasal HDM challenges over 4 d. Airway hyperreactivity (AHR), IgE, inflammatory cells, cytokines, leukotrienes, goblet cells, and activated T cells were assessed. In protocol 1, rapamycin blocked HDM-induced increases in AHR, inflammatory cell counts, and IgE, as well as attenuated goblet cell metaplasia. In protocol 2, rapamycin blocked increases in AHR, IgE, and T cell activation and reduced goblet cell metaplasia, but it had no effect on inflammatory cell counts. Increases in IL-13 and leukotrienes were also blocked by rapamycin, although increases in IL-4 were unaffected. These data demonstrated that rapamycin can inhibit cardinal features of allergic asthma, including increases in AHR, IgE, and goblet cells, most likely as a result of its ability to reduce the production of two key mediators of asthma: IL-13 and leukotrienes. These findings highlight the importance of the mTOR pathway in allergic airway disease.     

Anti-IL-13 monoclonal antibody inhibits airway hyperresponsiveness, inflammation and airway remodeling

Asthma is a chronic inflammatory disease characterized by reversible bronchial constriction, pulmonary inflammation and airway remodeling. Current standard therapies for asthma provide symptomatic control but fail to target the underlying disease pathology. Furthermore, no therapeutic agent is effective in preventing airway remodeling. Interleukin 13 (IL-13) is a pleiotropic cytokine produced mainly by T cells. A substantial amount of evidence suggests that IL-13 plays a critical role in the pathogenesis of asthma. Therefore, a neutralizing anti-IL-13 monoclonal antibody could provide therapeutic benefits to asthmatic patients. To test the concept we have generated a neutralizing rat anti-mouse IL-13 monoclonal antibody, and evaluated its effects in a chronic mouse model of asthma. Chronic asthma-like response was induced in ovalbumin (OVA) sensitized mice by repeated intranasal OVA challenges. After weeks of challenge, mice developed airway hyperresponsiveness (AHR) to methacholine stimulation, severe airway inflammation, hyper mucus production, and subepithelial fibrosis. When given at the time of each intranasal OVA challenge, anti-IL-13 antibody significantly suppressed AHR, eosinophil infiltration, proinflammatory cytokine/chemokine production, serum IgE, and most interestingly, airway remodeling. Taken together, these results strongly suggest that a neutralizing anti-human IL-13 monoclonal antibody could be an effective therapeutic agent for asthma.     

Differential Effects of Rapamycin and Dexamethasone in Mouse Models of Established Allergic Asthma

The mammalian target of rapamycin (mTOR) plays an important role in cell growth/differentiation, integrating environmental cues, and regulating immune responses. Our lab previously demonstrated that inhibition of mTOR with rapamycin prevented house dust mite (HDM)-induced allergic asthma in mice. Here, we utilized two treatment protocols to investigate whether rapamycin, compared to the steroid, dexamethasone, could inhibit allergic responses during the later stages of the disease process, namely allergen re-exposure and/or during progression of chronic allergic disease. In protocol 1, BALB/c mice were sensitized to HDM (three i.p. injections) and administered two intranasal HDM exposures. After 6 weeks of rest/recovery, mice were re-exposed to HDM while being treated with rapamycin or dexamethasone. In protocol 2, mice were exposed to HDM for 3 or 6 weeks and treated with rapamycin or dexamethasone during weeks 4–6. Characteristic features of allergic asthma, including IgE, goblet cells, airway hyperreactivity (AHR), inflammatory cells, cytokines/chemokines, and T cell responses were assessed. In protocol 1, both rapamycin and dexamethasone suppressed goblet cells and total CD4⁺ T cells including activated, effector, and regulatory T cells in the lung tissue, with no effect on AHR or total inflammatory cell numbers in the bronchoalveolar lavage fluid. Rapamycin also suppressed IgE, although IL-4 and eotaxin 1 levels were augmented. In protocol 2, both drugs suppressed total CD4⁺ T cells, including activated, effector, and regulatory T cells and IgE levels. IL-4, eotaxin, and inflammatory cell numbers were increased after rapamycin and no effect on AHR was observed. Dexamethasone suppressed inflammatory cell numbers, especially eosinophils, but had limited effects on AHR. We conclude that while mTOR signaling is critical during the early phases of allergic asthma, its role is much more limited once disease is established.     

Development of atopic dermatitis-like skin lesions in STAT6-deficient NC/Nga mice

Atopic dermatitis (AD) is a pruritic inflammatory skin disease characterized by elevation of plasma levels of total IgE, infiltration of mast cells and eosinophils, and the expression of cytokines by Th2 T cells. However, the role of Th2 cells in the pathogenesis of AD is not fully understood. In this study we examined the NC/Nga (NC) mouse model of AD and established STAT6-deficient (SATA6(-/-)) NC mice to investigate the relevance of IL-4-mediated immune responses. Surprisingly, these mice elicited AD-like skin lesions at equivalent frequency and time of onset compared with normal NC littermates. Histological features of the lesion in STAT6(-/-) NC mice fulfilled the criteria for the pathogenesis of AD, although these mice fail to produce IgE and Th2 cytokines. The lymph nodes proximal to the regions of skin that developed lesions exhibited massive enlargement elicited by the accumulation of activated IFN-gamma-secreting T cells. Moreover, caspase I, IL-18, IL-12, and IFN-gamma are found to be highly expressed at the skin lesion, occurring simultaneously with elevation of eotaxin 2 and CCR3 expression. Therefore, the Th2-mediated immune response is not necessary for the development of AD-like skin disease in NC mice. The skin microenvironment that favored IFN-gamma production tightly correlates with the skin disease in NC mice through the infiltration of eosinophils.     

Inhibitory effects of polysaccharide-rich extract of Phragmites rhizoma on atopic dermatitis-like skin lesions in NC/Nga mice

AimsPhragmites rhizoma was reported to have anti-oxidative and free radical scavenging activity. It also has been traditionally used to suppress inflammation. In the present study, we aimed to evaluate the topical effects of the polysaccharide-rich extract of P. rhizoma (PEP) on atopic dermatitis.Main methodsWe induced AD-like skin lesions by an extract of the house-dust mite Dermatophagoides farinae (Dfb) in NC/Nga mice, and then performed macroscopic analysis, immunohistochemical staining and measurement of total serum IgE and cytokine production by ELISA.Key findingsTopically applied PEP suppressed dermatitis with a decrease in dermatitis score and scratch number. The histological manifestations of atopic skin lesions including thickened epidermis and increased numbers of mast cells, polymorphonuclear leukocytes and nerve fibers were significantly attenuated. The activation of IgE and the levels of cytokines such as IFN-γ IL-4 and IL-10 were also decreased.SignificanceOur results indicated that PEP might have an inhibitory effect on atopic dermatitis-like lesion and be a promising natural resource in the treatment of atopic dermatitis.     

Inability of IL-12 to down-regulate IgE synthesis due to defective production of IFN-gamma in atopic NC/Nga mice.

NC/Nga mice raised in nonsterile circumstances spontaneously suffer from atopic dermatitis-like skin lesions with IgE hyperproduction. We investigated effects of rIL-12 on the IgE production in NC/Nga mice. rIL-12 administration was successful to suppress the increase of IgE levels in BALB/c mice immunized with OVA and aluminum hydroxide, but failed to abrogate that in NC/Nga mice. Both in vivo and in vitro IFN-gamma production induced by rIL-12 was less in NC/Nga mice than in BALB/c mice. Addition of rIFN-gamma to rIL-4 and LPS completely abrogated IgE production by B cells of BALB/c mice, but was insufficient to suppress it by B cells of NC/Nga mice. In splenic cells pretreated with Con A, STAT4 was phosphorylated at the tyrosine residue by addition of rIL-12, which was more weakly inducible in NC/Nga mice than in BALB/c mice. Finally, we examined the preventive ability of rIL-12 on the clinical aspects of atopic dermatitis in NC/Nga mice. rIL-12 administration resulted in exacerbation of development of the skin lesions and IgE production in NC/Nga mice raised in nonsterile circumstances. These results suggest that defective production of IFN-gamma by T cells less sensitive to IL-12 and low responsiveness of B cells to IFN-gamma may contribute to IgE hyperproduction in NC/Nga mice, and that IL-12 may have no ability to improve the clinical aspects of NC/Nga mice.     

Orally supplemented Lactobacillus acidophilus strain L‐92 inhibits passive and active cutaneous anaphylaxis as well as 2,4‐dinitroflurobenzene and mite fecal antigen induced atopic dermatitis‐like skin lesions in mice

Oral supplementation of lactic acid bacteria is a potential approach to the prevention and manipulation of allergic diseases such as atopic dermatitis. Our previous report showed that heat‐killed Lactobacillus acidophilus strain L‐92 (L‐92) possessed anti‐allergic properties, although its physiological function in atopic dermatitis has largely remained undefined. To evaluate the anti‐allergic efficacy of L‐92, we used four experimental animal models with the major features of atopic dermatitis and compared the results to those of clinically active drugs. ICR mice were passively sensitized by anti‐dinitrophenyl mouse monoclonal IgE for passive cutaneous anaphylaxis (PCA), and BALB/c mice were actively sensitized by ovalbumin for active cutaneous anaphylaxis (ACA). Allergic reaction was induced by repeated exposure to 2,4‐dinitroflurobenzene (DNFB) and mite (Dermatophagoides farinae) fecal allergen, in BALB/c and NC/Nga mice, respectively. Orally administrated L‐92 significantly inhibited the vascular permeability increase in both PCA and ACA, and the elevation of ovalbumin‐specific IgE titer in ACA. Moreover, repeated applications of DNFB and mite fecal antigen onto the BALB/c and NC/Nga mouse ear, respectively, caused clinical symptoms similar to atopic dermatitis such as ear swelling, scratching behavior and elevation of total serum IgE levels that were also moderately suppressed by L‐92. In addition, L‐92 treated mice exhibited lower levels of mast cells, eosinophil infiltration and Th1/Th2 cytokine expression. Our results, therefore, suggest that oral administration of L‐92 might be useful for alleviating allergic symptoms.