Repeated intratracheal inoculation of house dust mite (Dermatophagoides farinae) induces pulmonary eosinophilic inflammation and IgE antibody production in mice

Xin-Yi-Qing-Fei-Tang and its critical components reduce asthma symptoms by suppressing GM-CSF and COX-2 expression in RBL-2H3 cells

ETHNOPHARMACOLOGICAL RELEVANCE

The traditional Chinese medicine (TCM) XYQFT is composed of 10 herbs. According to the NHIRD, XYQFT is one of the top ten most commonly used TCM prescriptions for asthma treatment.

AIM OF THE STUDY

The aim of this study was to explore whether XYQFT reduces asthma symptoms in a mouse model of chronic asthma and determine the immunomodulatory mechanism of mast cells.

MATERIALS AND METHODS

BALB/c mice were intratracheally (it) stimulated with 40 μL (2.5 μg/μL) of Dermatophagoides pteronyssinus (Der p) once a week for 6 consecutive weeks and orally administered XYQFT at 1 g/kg 30 min before Der p stimulation. Airway hypersensitivity, inflammatory cells in the BALF and total IgE in the blood were assessed in mice. In addition, RBL-2H3 cells (mast cells) were stimulated with DNP-IgE, after which different concentrations of XYQFT were added for 30 min to evaluate the effect of XYQFT on the gene expression and degranulation of DNP-stimulated RBL-2H3 cells. After the compounds in XYQFT were identified using LC‒MS/MS, the PBD method was used to identify the chemical components that inhibited the expression of the GM-CSF and COX-2 genes in mast cells.

RESULTS

The airway hypersensitivity assay demonstrated that XYQFT significantly alleviated Der p-induced airway hypersensitivity. Moreover, cell counting and typing of bronchoalveolar lavage fluid revealed a significant reduction in Der p-induced inflammatory cell infiltration with XYQFT treatment. ELISA examination further indicated a significant decrease in Der p-induced total IgE levels in serum following XYQFT administration. In addition, XYQFT inhibited the degranulation and expression of genes (IL-3, IL-4, ALOX-5, IL-13, GM-CSF, COX-2, TNF-α, and MCP-1) in RBL-2H3 cells after DNP stimulation. The compounds timosaponin AIII and genkwanin in XYQFT were found to be key factors in the inhibition of COX-2 and GM-CSF gene expression in mast cells.

CONCLUSION

By regulating mast cells, XYQFT inhibited inflammatory cell infiltration, airway hypersensitivity and specific immunity in a mouse model of asthma. In addition, XYQFT synergistically inhibited the expression of the GM-CSF and COX-2 genes in mast cells through timosaponin AIII and genkwanin.

Effect of You-Gui-Wan on House Dust Mite-Induced Mouse Allergic Asthma via Regulating Amino Acid Metabolic Disorder and Gut Dysbiosis

Chinese herbal remedies have long been used for enhancing immunity and treating asthma. However, the evidence-based efficacy remains to be supported. This study aimed to explore the potential bio-signatures in allergic asthma and the effect of You-Gui-Wan (YGW), a traditional Chinese herbal prescription, on dust mite-induced mouse allergic asthma. Extract of Dermatophagoides pteronyssinus (Der p), a dust mite, was intratracheally administered to induce allergic asthma in mice. Serum metabolomic and 16S rRNA-based microbiome profiling were used to analyze untargeted metabolites with levels significantly changed and gut microbiota composition, respectively. Results indicated that 10 metabolites (acetylcarnitine, carnitine, hypoxanthine, tryptophan, phenylalanine, norleucine, isoleucine, betaine, methionine, and valine), mainly associated with branched-chain amino acid (BCAA) metabolism, aromatic amino acid (AAA) biosynthesis, and phenylalanine metabolism were markedly elevated after Der p treatment. YGW administration reversed the levels for 7 of the 10 identified metabolites, chiefly affecting BCAA metabolism. On 16S DNA sequencing, disordered Der p-induced gut microbiota was significantly alleviated by YGW. Multiple correlation analysis showed a good correlation between gut microbiota composition and levels of selected metabolites. Our study showed YGW administration effectively alleviated BCAA metabolic disorder and improved gut dysbiosis. This study provides support for YGW administration with benefits for allergic asthma.

Qi-Wei-Du-Qi-Wan and its major constituents exert an anti-asthmatic effect by inhibiting mast cell degranulation

ETHNOPHARMACOLOGICAL RELEVANCE

In Asia, Qi-Wei-Du-Qi-Wan (QWDQW) is a traditional Chinese medicine that has been used to treat chest tightness, cough, shortness of breath, night sweats, frequent urination and asthma. QWDQW is recorded in Yi Zong Yi Ren Pian (Medical Physician's Compilation), which was written by Yang Cheng Liu during the Qing Dynasty.

AIM OF THE STUDY

The traditional Chinese medicine QWDQW is composed of 7 ingredients and has been used in the treatment of asthma in Asia for hundreds of years. However, the mechanism through which QWDQW affects the immune system in the treatment of asthma is not known. Therefore, this study aimed to investigate whether QWDQW alleviates asthmatic symptoms in mice with chronic asthma induced by repeated stimulation with Dermatophagoides pteronyssinus (Der p) and to explore the underlying immune modulatory mechanism.

MATERIALS AND METHODS

BALB/c mice were stimulated intratracheally (i.t.) with Der p (40 μl, 2.5 μg/μl) once weekly for 6 weeks. Thirty minutes prior to Der p stimulation, the mice were treated with QWDQW (0.5 g/kg and 0.17 g/kg) orally. Three days after the last stimulation, the mice were sacrificed, and infiltration of inflammatory cells, lung histological characteristics, gene expression of lung and serum total IgE were assessed. In other experiments, RBL-2H3 cells were stimulated with DNP-IgE/DNP-BSA and then treated with QWDQW, quercetin, β-carotene, luteolin or a mixture of the three chemicals (Mix13) for 30 min, and the effects of the drugs on RBL-2H3 cell degranulation after DNP stimulation were determined.

RESULTS

QWDQW significantly reduced Der p-induced airway hyperreactivity (AHR) and decreased total serum IgE and Der p-specific IgE levels. Histopathological examination showed that QWDQW reduced inflammatory cell infiltration and sputum secretion from goblet cells in the lungs. Gene expression analysis indicated that QWDQW reduced overproduction of IL-12、IFN-γ、IL-13、IL-4、RNATES、Eotaxin and MCP-1in lung. Additionally, QWDQW and Mix13 suppressed DNP induced RBL-2H3 degranulation, and the effect was maximal when quercetin, β-carotene and luteolin were administered together.

CONCLUSION

These results indicate that QWDQW plays a role in suppressing excessive airway reaction and in specific immune modulation in a mouse model of chronic asthma and that QWDQW suppresses mast cell degranulation at defined doses of quercetin, β-carotene and luteolin.

DFSG, a novel herbal cocktail with anti-asthma activity, suppressed MUC5AC in A549 cells and alleviated allergic airway hypersensitivity and inflammatory cell infiltration in a chronic asthma mouse model

AIM OF THE STUDY

To develop a novel anti-asthma drug. DFSG is a novel herbal cocktail composed of 4 types of herbal medicines. This study explored whether DFSG has the potential to attenuate asthma symptom severity and aimed to determine the immunomodulatory mechanism of DFSG using a chronic asthmatic mouse model induced by repeated challenges with Dermatogoides pteronyssinus (Der p).

MATERIALS AND METHODS

BALB/c mice were intratracheally inoculated with Der p (50 μl, 1 mg/ml) once a week for 5 weeks. In addition, 30 min before Der p challenge, the mice were orally administered 1x DFSG (1 g/kg) or 1/2x DFSG (0.5 g/kg). Three days after the final challenge, the mice were sacrificed to evaluate inflammatory cell infiltration, lung histological features, blood total IgE, and cytokine levels in pulmonary alveolar lavage fluid. Furthermore, 30 min after the addition of DFSG, caffeic acid, p-coumaric acid or chlorogenic acid to A549 cells, 10 ng/ml IL-1β was added to evaluate the effect of the drug on mucin 5AC (MUC5AC) gene expression after stimulation of A549 cells by IL-1β.

RESULTS

DFSG significantly reduced Der p-induced airway hyperresponsiveness, bronchial inflammatory cell infiltration, and total IgE and IgG1 serum levels. Furthermore, DFSG significantly inhibited T_H2 cytokines and increased the expression of T_H1 cytokines. In addition, immunohistochemical staining demonstrated that DFSG inhibited MUC5AC expression in the bronchial epithelial cells. DFSG and a mixture of caffeic acid, p-coumaric acid, and chlorogenic acid inhibited MUC5AC gene expression in A549 cells after stimulation with IL-1β.

CONCLUSION

These results suggest that by regulating T_H1 and T_H2 cytokines and MUC5AC expression, DFSG exhibits anti-airway inflammatory cell infiltration and anti-hyperresponsiveness activity and inhibits specific immunity in a chronic asthmatic mouse model. Therefore, DFSG has potential for development into a drug for chronic asthma treatment.

Jin Gui Shen Qi Wan, a traditional Chinese medicine, alleviated allergic airway hypersensitivity and inflammatory cell infiltration in a chronic asthma mouse model

ETHNOPHARMACOLOGICAL RELEVANCE

In Asia, Jin Gui Shen Qi Wan (JGSQW) has been used for hundreds of years to treat asthma.

AIM OF THE STUDY

The traditional Chinese medicine JGSQW is composed of Rehmannia glutinosa, Dioscorea opposita, Cornus officinalis, Poria cocos, Paeonia suffruticosa, Alisma orientalis, Aconitum carmichaelii and Cinnamomum cassia. However, the immunological mechanism underlying the effect of JGSQW treatment on asthma remains unclear. This study examined whether JGSQW has the potential to reduce asthma symptoms in mice with chronic asthma induced by recurrent Dermatophagoides pteronyssinus (Der p) stimulation, as well as its immunoregulatory mechanisms.

MATERIALS AND METHODS

The airways of BALB/c mice were stimulated with Der p (i.t.) once per week (50 μL, 1 mg/mL) for 6 consecutive weeks, and the mice were fed JGSQW (1 g/kg) 30 min prior to the Der p stimulation. Three days after the last stimulation, the mice were sacrificed to evaluate the airway remodelling, infiltration of inflammatory cells, lung histological features, and total IgE in the blood. Additionally, after A549 cells were treated with JGSQW, loganin, or paeoniflorin for 30 min, 10 ng/mL IL-1β was added to stimulate the A549 cells to evaluate the effect of the medicine on the ICAM-1 gene expression after IL-1β stimulation.

RESULTS

JGSQW significantly reduced the Der p-induced infiltration of inflammatory cells into airways and decreased the total IgE and Der p-specific IgG1 in serum. Collagen assays and histopathological examinations showed that JGSQW reduced lung airway remodelling. Additionally, an electrophoretic mobility shift assay and immunohistochemical staining verified that JGSQW inhibited the NF-kB expression in airway epithelial cell nuclei. JGSQW, loganin, and paeoniflorin inhibited the ICAM-1 gene expression caused by the IL-1β stimulation of A549 cells, and loganin and paeoniflorin had the maximum inhibitory effect when mixed according to the combination of doses in JGSQW.

CONCLUSION

These results indicated that in the chronic asthma mouse model, JGSQW inhibits the infiltration of inflammatory cells into the airways and airway remodelling and exhibits specific immunoregulatory effects. JGSQW with certain doses of loganin and paeoniflorin inhibited ICAM-1 gene expression in epithelial cells.

Frontline Science: RIP2 promotes house dust mite-induced allergic airway inflammation

House dust mites (HDMs) are one of the most significant environmental allergens in the establishment of the so-called "Atopic March." It is known that the immune response to HDM is Th2 dominant, but the innate mechanisms leading to HDM-induced type 2 responses are still not completely understood. A number of innate immune receptors have been implicated in the response to HDM including toll-like receptors, C-type lectin receptors, and protease activated receptors. NOD2 is a member of the NOD-like receptor family, which has been reported to be involved in the establishment of type 2 immunity and in blocking respiratory tolerance. NOD2 mediates its effects through its downstream effector kinase, receptor interacting protein (RIP2). It has not been shown if RIP2 is involved in the innate response to HDM and in the resulting generation of type 2 immunity. Furthermore, the role of RIP2 in modulating allergic airway inflammation has been controversial. In this study, we show that RIP2 is activated in airway epithelial cells in response to HDM and is important for the production of CCL2. Using a murine HDM asthma model, we demonstrate that lung pathology, local airway inflammation, inflammatory cytokines, HDM-specific IgG1 antibody production, and HDM-specific Th2 responses are all reduced in RIP2 knockout mice compared to WT animals. These data illustrate that RIP2 can be activated by a relevant allergic stimulus and that such activation can contribute to allergic airway inflammation. These findings also suggest that RIP2 inhibitors might have some efficacy in down-regulating the inflammatory response in type 2 dominated diseases.

Extent of allergic inflammation depends on intermittent versus continuous sensitization to house dust mite

OBJECTIVE

House dust mite (HDM) exposure is used to model experimental asthma in mice. However, a direct comparison of inflammatory responses following continuous versus intermittent HDM exposure has not been reported. Therefore, we investigated whether the HDM dose at sensitization or challenge affects extent of inflammation in mice that were either continuously or intermittently sensitized with HDM.

MATERIALS AND METHODS

C57BL/6 mice received either 10 continuous exposures with 10 μg HDM per exposure or two intermittent HDM exposures over a period of two weeks and were subsequently challenged by three instillations with HDM during the third week. For the intermittent model, mice were sensitized with 1 or 10 μg HDM and challenged on three consecutive days with 1 or 10 μg HDM. Inflammatory cells in the bronchoalveolar lavage fluid and epithelial cell hyperplasia and mucous cell metaplasia were quantified.

RESULTS

Significantly higher levels of inflammation and mucous cell metaplasia were observed when mice were sensitized intermittently compared with continuously. Intermittent sensitization and challenge with 10 μg HDM caused maximum inflammation, mucous cell metaplasia, and epithelial cell hyperplasia. However, sensitization with 1 μg HDM only also showed increased inflammation when challenged with 10 μg HDM.

DISCUSSION

These findings suggest major differences in adaptive immunity, depending on the sensitization protocol.

CONCLUSIONS

Because of significant differences, the HDM sensitization protocol should be carefully considered when designing studies to investigate the underlying mechanisms of immunity in mouse models of asthma.

Pretreatment with a heat-killed probiotic modulates monocyte chemoattractant protein-1 and reduces the pathogenicity of influenza and enterovirus 71 infections

It has been proposed that inactivated probiotics may modulate the host immune system and contribute to mitigation of viral infections. This study demonstrated that administration of heat-killed Enterococcus faecalis, a widely used probiotic, can protect host animals against viral infections. The influenza-mediated morbidity and lung inflammation in E. faecalis-treated mice decreased significantly compared with those of the control mice. Furthermore, we found that the protection is associated with production of monocyte chemoattractant protein-1 (MCP-1). The intratracheal injection of a recombinant mouse MCP-1 protein abrogated the antiviral effects elicited by pretreatment with E. faecalis. CC chemokine receptor 2 (CCR2) is a receptor for MCP-1, and the intraperitoneal administration of a CCR2 antagonist effectively inhibited viral pathogenicity. The reduced pathogenicity was also observed in CCR2-deficient mice. Finally, E. faecalis significantly attenuated neuropathogenicity induced by another RNA virus, enterovirus 71. This study demonstrates that killed probiotics can reduce viral disease severity and identify that the MCP-1 pathway might act as a key mediator in the improved antiviral immune response. Our findings suggest that MCP-1 and its related signaling pathway can serve as critical therapeutic targets for development of new antiviral strategies.

CD4⁺ and CD8⁺ T cells play a central role in a HDM driven model of allergic asthma

Background

The incidence of asthma is increasing at an alarming rate and while the current available therapies are effective in the majority of patients they fail to adequately control symptoms at the more severe end of the disease spectrum. In the search to understand disease pathogenesis and find effective therapies animal models are often employed. As exposure to house dust mite (HDM) has a causative link, it is thought of as the allergen of choice for modelling asthma.

The objective was to develop a HDM driven model of asthmatic sensitisation and characterise the role of key allergic effector cells/mediators.

Methods

Mice were sensitised with low doses of HDM and then subsequently challenged. Cellular inflammation, IgE and airway responsiveness (AHR) was assessed in wild type mice or CD4⁺/CD8⁺ T cells, B cells or IgE knock out mice.

Results

Only those mice sensitised with HDM responded to subsequent low dose topical challenge. Similar to the classical ovalbumin model, there was no requirement for systemic alum sensitisation. Characterisation of the role of effector cells demonstrated that the allergic cellular inflammation and AHR was dependent on CD4⁺ and CD8⁺ T cells but not B cells or IgE. Finally, we show that this model, unlike the classic OVA model, appears to be resistant to developing tolerance.

Conclusions

This CD4⁺/CD8⁺ T cell dependent, HDM driven model of allergic asthma exhibits key features of asthma. Furthermore, we suggest that the ability to repeat challenge with HDM means this model is amenable to studies exploring the effect of therapeutic dosing in chronic, established disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-016-0359-y) contains supplementary material, which is available to authorized users.

Nitric oxide suppresses LPS-induced inflammation in a mouse asthma model by attenuating the interaction of IKK and Hsp90

A feature of allergic airway disease is the observed increase of nitric oxide (NO) in exhaled breath. Gram-negative bacterial infections have also been linked with asthma exacerbations. However, the role of NO in asthma exacerbations with gram-negative bacterial infections is still unclear. In this study, we examined the role of NO in lipopolysaccharide (LPS)-induced inflammation in an ovalbumin (OVA)-challenged mouse asthma model. To determine whether NO affected the LPS-induced response, a NO donor (S-nitroso-N-acetylpenicillamine, SNAP) or a selective inhibitor of NO synthase (1400W) was injected intraperitoneally into the mice before the LPS stimulation. Decreased levels of proinflammatory cytokines were demonstrated in the bronchoalveolar lavage fluid from mice treated with SNAP, whereas increased levels of cytokines were found in the 1400W-treated mice. To further explore the molecular mechanism of NO-mediated inhibition of proinflammatory responses in macrophages, RAW 264.7 cells were treated with 1400W or SNAP before LPS stimulation. LPS-induced inflammation in the cells was attenuated by the presence of NO. The LPS-induced IκB kinase (IKK) activation and the expression of IKK were reduced by NO through attenuation of the interaction between Hsp90 and IKK in the cells. The IKK decrease in the lung immunohistopathology was verified in SNAP-treated asthma mice, whereas IKK increased in the 1400W-treated group. We report for the first time that NO attenuates the interaction between Hsp90 and IKK, decreasing the stability of IKK and causing the down-regulation of the proinflammatory response. Furthermore, the results suggest that NO may repress LPS-stimulated innate immunity to promote pulmonary bacterial infection in asthma patients.

The effect of serine protease inhibitors on airway inflammation in a chronic allergen-induced asthma mouse model

Serine protease inhibitors reportedly attenuated airway inflammation and had antioxidant in multiorgan. However, the effects of the serine protease inhibitors nafamostat mesilate (FUT), gabexate mesilate (FOY), and ulinastatin (UTI) on a long-term challenged mouse model of chronic asthma are unclear. BALB/c mice (6 mice/group) were intratracheally inoculated with five doses of Dermatophagoides pteronyssinus (Der p; 50 μL, 1 mg/mL) at one-week intervals. Therapeutic doses of FUT (0.0625 mg/kg), FOY (20 mg/kg), or UTI (10,000 U/kg) were, respectively, injected intraperitoneally into these mice. Control mice received sterile PBS. At 3 days after the last challenge, mice were sacrificed to assess airway hyperresponsiveness (AHR), remodeling, and inflammation; lung histological features; and cytokine expression profiles. Compared with untreated controls, mice treated with FUT, FOY, and UTI had decreased AHR and goblet cell hyperplasia, decreased eosinophil and neutrophil infiltration, decreased Der p-induced IL-4 levels in serum and IL-5, IL-6, IL-13, and IL-17 levels in bronchoalveolar lavage fluid, and inhibited nuclear factor (NF)-κB activity in lung tissues. The serine protease inhibitors FUT, FOY, and UTI have potential therapeutic benefits for treating asthma by downregulating Th2 cytokines and Th17 cell function and inhibiting NF-κB activation in lung tissue.

Xiao-Qing-Long-Tang attenuates allergic airway inflammation and remodeling in repetitive Dermatogoides pteronyssinus challenged chronic asthmatic mice model

ETHNOPHARMACOLOGICAL RELEVANCE

Xiao-Qing-Long-Tang (XQLT) has been used for centuries in Asia to effectively treat patients with bronchial asthma.

AIM OF THE STUDY

We previously found that single and multiple doses of XQLT administered to sensitized mice before allergen challenge resulted in suppressed airway hyper-responsiveness and airway inflammation. In this study we aimed to investigate whether XQLT has the potential to attenuate the severity of asthma symptoms, and immunomodulatory mechanism of XQLT in a repetitive Dermatogoides pteronyssinus (D. pteronyssinus)-challenged chronic asthmatic mice model.

MATERIALS AND METHODS

BALB/c mice were intratracheally (i.t.) inoculated with five doses of D. pteronyssinus (50 μl, 1mg/ml) and orally administered of XQLT (1 g/kg) at 1-week intervals. At three days after the last challenge, mice were sacrificed to evaluate airway remodeling, inflammation, lung histological features, and the expression profiles of cytokines and various genes.

RESULTS

XQLT significantly reduced bronchial inflammatory cell infiltration and airway remodeling. It inhibited D. pteronyssinus-induced total IgE and D. pteronyssinus-specific IgG1 in serum, and changed the "T(H)2-bios" in BALF by inhibiting the activation of NF-κB. Collagen assay and Histopathology indicated that XQLT reduced airway remodeling in the lung. Simultaneously, the RT-PCR analysis showed that XQLT downregulated IL-10, IL-13, RANTES, Eotaxin, and MCP-1 mRNA expression in the lung. Moreover, EMSA and immunohistochemistry staining demonstrated that XQLT inhibited NF-κB expression in the nucleus of bronchial epithelial cells.

CONCLUSIONS

These results suggest that XQLT exhibits anti-airway inflammatory, anti-airway remodeling, and specific immunoregulatory effects in a chronic asthmatic mice model.

The Immunomodulatory Effect of You-Gui-Wan on Dermatogoides-pteronyssinus-Induced Asthma

The traditional Chinese medicine You-Gui-Wan (YGW) contains ten species of medicinal plants and has been used to improve health in remissive states of asthma for hundreds of years in Asia. However, little is known about the immunomodulatory mechanisms in vivo. Therefore, this study investigated the pathologic and immunologic responses to YGW in mice that had been repeatedly exposed to Dermatogoides-pteronyssinus (Der p). YGW reduced Der-p-induced airway hyperresponsiveness and total IgE in serum. It also inhibited eosinophil infiltration by downregulating the protein expression of IL-5 in serum and changed the Th2-bios in BALF by upregulating IL-12. Results of the collagen assay and histopathologic examination showed that YGW reduced airway remodeling in the lung. In addition, after YGW treatment there was a relative decrease in mRNA expression of TGF-β1, IL-13, eotaxin, RANTES, and MCP-1 in lung in the YGW group. The results of EMSA and immunohistochemistry revealed that YGW inhibited NF-κB expression in epithelial lung cells. YGW exerts its regulative effects in chronic allergic asthmatic mice via its anti-inflammatory activity and by inhibiting the progression of airway remodeling.

Increase in allergen-specific IgE and ex vivo Th2 responses after a single bronchial challenge with house dust mite in allergic asthmatics

BACKGROUND

  Airway responsiveness to allergen in patients with allergic asthma is studied by bronchial allergen challenge. Although the typical features of the early and late responses on lung function and bronchial inflammation after allergen challenge are well known, little has been reported as yet on any changes in systemic allergic and immunologic parameters after 4-6 weeks.

METHODS

  In a clinical study, 27 subjects with allergic asthma and house dust mite (HDM) allergy underwent a bronchial allergen challenge with HDM. Blood samples were collected before and 5 weeks after allergen challenge. Serum levels of total IgE and allergen-specific IgE were measured, and peripheral blood mononuclear cells were isolated and stimulated ex vivo with HDM to determine the allergen-specific T-cell cytokine response.

RESULTS

  Five weeks after bronchial allergen challenge with HDM, the amount of circulating IgE against HDM and the major allergenic components Der p1 and Der p2 was significantly increased (10.8% and 8.8%, respectively). IgE antibodies against other environmental allergens decreased (grass pollen) or remained unchanged (cat dander). Allergen-induced Th2-cytokine production was also significantly increased (P< 0.001, P=0.014, and P=0.006 for IL-4, IL-5, and IL-13, respectively). The increase in Der p1- and Der p2-specific IgE in serum correlated with increased numbers of Th2-cytokine-producing cells (Rs=0.56, P=0.002 and Rs=0.54, P=0.004 for IL-4 and IL-13, respectively).

CONCLUSIONS

  A single bronchial allergen challenge with HDM is accompanied by increased levels of allergen-specific IgE for HDM in serum and an enhanced Th2 response to HDM still detectable 5 weeks after challenge.

The protease allergen Pen c 13 induces allergic airway inflammation and changes in epithelial barrier integrity and function in a murine model

Fungal allergens are associated with the development of asthma, and some have been characterized as proteases. Here, we established an animal model of allergic airway inflammation in response to continuous exposure to proteolytically active Pen c 13, a major allergen secreted by Penicillium citrinum. In functional analyses, Pen c 13 exposure led to increased airway hyperresponsiveness, significant inflammatory cell infiltration, mucus overproduction, and collagen deposition in the lung, dramatically elevated serum levels of total IgE and Pen c 13-specific IgE and IgG1, and increased production of the Th2 cytokines IL-4, IL-5, and IL-13 by splenocytes stimulated in vitro with Pen c 13. To examine the mechanisms involved in the regulation of allergenicity by Pen c 13, we performed two-dimensional fluorescence difference gel electrophoresis analysis combined with nano-LC-MS/MS, followed by bioinformatics analysis to identify potential targets that associated with allergic inflammation, which suggested that galectin-3 and laminin might be involved in novel pathogenic mechanisms. Finally, we focused on junctional proteins between cells, because, in addition to opening of the epithelial barrier by environmental proteases possibly being the initial step in the development of asthma, these proteins are also associated with actin rearrangement. Taken together, our findings indicate that Pen c 13 exposure causes junctional structure alterations and actin cytoskeletal rearrangements, resulting in increased permeability and airway structural changes. These effects probably change the lung microenvironment and foster the development of allergic sensitization.

Development of two animal models to study the function of Vibrio parahaemolyticus type III secretion systems

Vibrio parahaemolyticus is an emerging food- and waterborne pathogen that encodes two type III secretion systems (T3SSs). Previous studies have linked type III secretion system 1 (T3SS1) to cytotoxicity and T3SS2 to intestinal fluid accumulation, but animal challenge models needed to study these phenomena are limited. In this study we evaluated the roles of the T3SSs during infection using two novel animal models: a model in which piglets were inoculated orogastrically and a model in which mice were inoculated in their lungs (intrapulmonarily). The bacterial strains employed in this study had equivalent growth rates and beta-hemolytic activity based on in vitro assays. Inoculation of 48-h-old conventional piglets with 10(11) CFU of the wild-type strain (NY-4) or T3SS1 deletion mutant strains resulted in acute, self-limiting diarrhea, whereas inoculation with a T3SS2 deletion mutant strain failed to produce any clinical symptoms. Intrapulmonary inoculation of C57BL/6 mice with the wild-type strain and T3SS2 deletion mutant strains (5 × 10(5) CFU) induced mortality or a moribund state within 12 h (80 to 100% mortality), whereas inoculation with a T3SS1 deletion mutant or a T3SS1 T3SS2 double deletion mutant produced no mortality. Bacteria were recovered from multiple organs regardless of the strain used in the mouse model, indicating that the mice were capable of clearing the lung infection in the absence of a functional T3SS1. Because all strains had a similar beta-hemolysin phenotype, we surmise that thermostable direct hemolysin (TDH) plays a limited role in these models. The two models introduced herein produce robust results and provide a means to determine how different T3SS1 and T3SS2 effector proteins contribute to pathogenesis of V. parahaemolyticus infection.

Early-life co-administration of cockroach allergen and endotoxin augments pulmonary and systemic responses

BACKGROUND

Environmental exposures to cockroach allergen and endotoxin are recognized epidemiological risk factors for the early development of allergies and asthma in children. Because of this, it is important to examine the role of early-life concurrent inhalation exposures to cockroach allergen and endotoxin in the pathogenesis of allergic airways disease.

OBJECTIVE

We examined the effects of repeated concomitant endotoxin and cockroach allergen inhalation on the pulmonary and systemic immune responses of newborn and juvenile mice.

METHODS

C3H/HeBFeJ mice were exposed to inhaled endotoxin and cockroach allergen via intranasal instillation from day 2 to 21 after birth, and systemic and pulmonary responses were examined in serum, bronchoalveolar lavage fluid, and lung tissue.

RESULTS

Cockroach allergen exposures induced pulmonary eosinophilic inflammation, total and allergen-specific IgE, IgG(1), and IgG(2a) production, and alveolar remodelling. Co-exposures with endotoxin and cockroach allergen significantly increased serum IgE and IgG(1), lung inflammation, and alveolar wall thickness, and decreased airspace volume density. Importantly, compared with exposures with individual substances, the responses to co-exposures were more than additive.

CONCLUSIONS

Repeated inhalation exposures of neonatal and juvenile mice to endotoxin and cockroach allergen increased the pulmonary inflammatory and systemic immune responses in a synergistic manner and enhanced alveolar remodelling in the developing lung. These data underscore the importance of evaluating the effect of multiple, concurrent environmental exposures, and of using an experimental model that incorporates clinically relevant timing and route of exposures.

Repeated instillations of Dermatophagoides farinae into the airways can induce Th2-dependent airway hyperresponsiveness, eosinophilia and remodeling in mice: effect of intratracheal treatment of fluticasone propionate

Dermatophagoides farinae are known to be a common environmental allergen causing allergic asthma; however, little is known about their pathophysiological effect via the allergenicities in vivo. Therefore, we first established a mouse model of asthma induced by repeated instillations of D. farinae. Second, to investigate whether the asthmatic responses are Th2-dependent, we examined the effect of the deficiency of interleukin-4 (IL-4) receptor alpha chain gene. Finally, we examined the effect of fluticasone propionate on this model. Mice were instilled with D. farinae without additional adjuvants into the trachea 8 times. After the final allergen instillation, the airway responsiveness to acetylcholine was measured, and bronchoalveolar lavage and histological examination were carried out. The instillation of the allergen-induced airway hyperresponsiveness, the accumulation of inflammatory cells and increases in the levels of Th2 cytokines and transforming growth factor-beta(1) production in the bronchoalveolar lavage fluid dose dependently. The number of goblet cells in the epithelium and the extent of the fibrotic area beneath the basement membrane were also increased in the morphometric study. In contrast, the defect of IL-4/IL-13 signaling through IL-4 receptor alpha chain completely abrogated all these responses. Furthermore, the simultaneous instillation of fluticasone propionate with the allergen showed significant inhibition or an inhibitory tendency of these changes. These findings demonstrate that the repetitive intratracheal instillations of D. farinae can induce airway remodeling through Th2-type inflammation, and that fluticasone propionate inhibits D. farinae-induced airway remodeling in mice, and this model would be useful for studying mechanisms involved in the development of allergic asthma.

Intranasal mite allergen induces allergic asthma-like responses in NC/Nga mice

Airway responses induced by intranasal administration of mite allergen without adjuvant were studied in NC/Nga mice. A crude extract of Dermatophagoides farinae (Df) was administered for 5 consecutive days and a single intranasal challenge booster dose was given 1 week after the last sensitization. 24 h after the single challenge, the airway hyperresponsiveness (AHR) was measured and the bronchoalveolar lavage fluid (BALF) was analyzed for numbers of eosinophils and neutrophils, and both cytokine and chemokine levels. There were marked increases in number of eosinophils in the BALF, AHR, Th2 cytokines (IL-5 and IL-13), and chemokine (eotaxin-1 and eotaxin-2) levels in the BALF following Df exposure. C57BL/6N, A/J, BALB/c, and CBA/JN mouse strains were also exposed to Df crude extract, but all of the measured responses were strongest in NC/Nga mice. Furthermore, Df-exposed NC/Nga mice showed the goblet cell hyperplasia, pulmonary eosinophilic inflammation, and increases in both total serum IgE and Df-specific IgG1. After intranasal exposure of NC/Nga mice to crude extract of Dermatophagoides pteronyssinus, the BALF eosinophilia and AHR were similar to responses induced by Df. None of the study parameters were increased in response to intranasal exposure to ovalbumin. These data demonstrated that NC/Nga mice developed allergic asthma-like responses after intranasal exposure to mite allergens.

IL-19 induced Th2 cytokines and was up-regulated in asthma patients

IL-19 belongs to the IL-10 family, which includes IL-10, IL-19, IL-20, IL-22, melanoma differentiation-associated gene-7 (IL-24), and AK155 (IL-26). IL-10 has been shown to inhibit allergen-induced airway hyperreactivity and inflammation. To determine whether IL-19 was also associated with asthma, we used ELISA to analyze the serum level of IL-19 in patients with asthma and found that their serum IL-19 levels were twice those of healthy controls. Patients with a high level of IL-19 also had high levels of IL-4 and IL-13. In a dust mite-induced murine model of asthma, we found that IL-19 level in asthmatic BALB/cJ mice was also twice that of healthy control mice. IL-19 transcript was also induced in the lungs of asthmatic mice. Electroporation i.m. of the IL-19 gene into healthy mice up-regulated IL-4 and IL-5, but not IL-13. However, IL-19 up-regulated IL-13 in asthmatic mice. In vitro, IL-19 induced IL-4, IL-5, IL-10, and IL-13 production by activated T cells. Activation of T cells was required for induction of IL-13 because IL-19 did not induce IL-13 production on nonstimulated T cells. Taken together, these results demonstrated that IL-19 up-regulates Th2 cytokines on activated T cells and might play an important role in the pathogenesis of asthma.

Activation of mast cells is essential for development of house dust mite Dermatophagoides farinae-induced allergic airway inflammation in mice

In this study, we demonstrate that Dermatophagoides farinae (Der f), a major source of airborne allergens, but not OVA, could rapidly activate mast cells in mice. This was indicated by an elevation of serum mouse mast cell protease 1, a mast cell-specific proteinase, as early as 30 min after intratracheal challenge. Administration of sodium cromoglycate (40 mg/kg, i.p., 1 h before Der f instillation), a mast cell stabilizer, not only suppressed acute mouse mast cell protease 1 production but also attenuated the allergic airway inflammation provoked by repetitive Der f challenge in mice (five times at 1-wk interval). Der f induced the expression of mRNA for TNF-alpha, IL-1beta, IL-4, IL-6, IL-9, and IL-13 in mastocytoma P815 cells and stimulated both P815 cells and bone marrow-derived mast cells to produce IL-4, IL-6, and TNF-alpha in a dose- and time-dependent manner. Cycloheximide as well as sodium cromoglycate blocked the Der f-induced IL-4 production, indicating a de novo protein synthesis process. Supernatants of Der f-stimulated mast cells chemoattracted monocytes and T lymphocytes; they up-regulated the expression of costimulatory B7 molecules, eotaxin, RANTES, monocyte chemoattractant protein 1, and IFN-inducible protein 10 mRNA of alveolar macrophages; they supported PHA-induced T cell proliferation; and they promoted Th2 cell development. Our data indicate that mast cells may be an important cell type during the initiation of Der f sensitization in the airway by modulating the function of alveolar macrophages and T cells.

House dust mite Dermatophagoides farinae augments proinflammatory mediator productions and accessory function of alveolar macrophages: implications for allergic sensitization and inflammation

In this study, we examine the effects of Dermatophagoides farinae (Der f), a major source of airborne allergens, on alveolar macrophages (AMs), and we also test its contribution to allergic responses in mice. Der f activated NF-kappaB of AMs and, unlike OVA or LPS stimulation, up-regulated IL-6, TNF-alpha, and NO. In addition, it down-regulated antioxidants, but affected neither the expression nor production of IL-12. Der f-stimulated AMs expressed enhanced levels of costimulatory B7 molecules, supported T cell proliferation, and promoted Th2 cell development. The enhanced accessory function was suppressed by blockade mAbs to B7.2, IL-6, and TNF-alpha and by N-monomethyl-L-arginine, an NO synthase inhibitor, and N-acetylcysteine, a thiol antioxidant, whereas it was augmented by (+/-)-S-nitroso-N-acetylpenicillamine, an NO donor. Arg-Gly-Asp-Ser peptide and neo-glycoproteins galactose-BSA and mannose-BSA inhibited the Der f-induced IL-6 and TNF-alpha productions and enhanced accessory function of AMs. Der f was more potent than OVA for inducing pulmonary eosinophilic inflammation, NO, and serum allergen-specific IgG1 Ab production in mice. AMs from Der f-challenged mice expressed enhanced levels of B7 and augmented T cell proliferation ex vivo. In Der f-challenged mice, respiratory syncytial virus infection (5 x 10(5) pfu; 3 days before Der f instillation) augmented Der f-specific Ab production, whereas dexamethasone (50 mg/kg; 1 h before Der f instillation) diminished the allergic airway inflammation and Ab response. We conclude that AMs are sensitive targets for Der f and that the Der f-induced proinflammatory responses may represent an important mechanism in mediating the development of allergic sensitization and inflammation.