OVA Inhalation Research Articles

Regulation of ferroptosis and ACSL4-15LO1 pathway contributed to the anti-asthma effect of acupuncture.

Acupuncture has been frequently used in China for the treatment asthma for thousands of years. Ferroptosis was recently revealed to be involved in several pathological conditions including asthma. However, the detailed links between ferroptosis and airway inflammation in asthma, as well as the detailed regulation of acupuncture on these disorders remains unclear. Our results demonstrated that the non-haem Fe2+ level increased markedly in the lung tissue of mouse asthma model, and positively correlated with RL and IL-4 level in BALF. Furthermore, lipid peroxidation markers MDA and GSSG increased remarkably in OVA-induced experimental asthma mice. Up-regulation of lipid peroxidation associated proteins ACSL4 and15-LO1 was also observed in OVA-induced experimental asthma mice. To demonstrate the role of ferroptosis in asthma and the effect of acupuncture on these disorders, ferroptosis-induction agent erastin and ferroptosis-inhibition agent fer-1 were used, and our data demonstrated that erastin could augment lung inflammation and lipid peroxidation in OVA induced asthma model. Fer-1 was able to relieve AHR, lung inflammation, non-haem Fe2+ level, lipid peroxidation and ferroptosis related pathway ACSL4-15LO1 in OVA-induced experimental asthma mice. Acupuncture treatment alleviated RL, lung inflammation as well as type 2 cytokines IL-4 and IL-13 levels induced by OVA inhalation. What's more, acupuncture significantly reduced the MDA and GSSG levels, the non-haem Fe2+ level and ACSL4-15-LO1 proteins expression. Acupuncture also relieved erastin-induced exacerbation in lung inflammation and lipid peroxidation in ferroptosis. Acupuncture treatment could relieve ferroptosis related exacerbation in airway inflammation. Our study provided insights into the underlying mechanisms for the protective effects of acupuncture and highlighted a therapeutic potential of acupuncture treatment in the attenuation of lipid peroxidation and ferroptosis in asthma.

Airway remodeling is reversed by aerobic training in a murine model of chronic asthma.

The aim of this study was to investigate if the aerobic training (AT) reverses airway remodeling (AR) in an asthma model. BALB/c were divided into four groups: control (unsensitized and untrained); ovalbumin (OVA: sensitized and untrained); AT (unsensitized and trained) and OVA + AT. Allergic inflammation was induced with intraperitoneal and OVA inhalation. AT (low intensity; 5×/week; 60 min/session) was performed at 7, 15, and 30 days. Leukocyte counting in the bronchoalveolar lavage fluid; the expression of IL-5, eotaxin, RANTES, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1); AR features (airway smooth muscle, epithelium thickness, collagen and elastic fibers, mucus production); and AR inducers (transforming growing factor-beta, osteopontin, vascular endothelial growth factor). OVA induced an increase in leukocyte airway migration and increased AR features (P < 0.05). After 7 days, AT reversed the OVA-induced eosinophil and macrophage airway migration, the expression of IL-5, eotaxin, RANTES, ICAM-1, VCAM-1, and all AR inducers. However, total reversion of the AR features and inducers and airway inflammation occurred only after 15 days of AT compared with the OVA groups (P < 0.05) and the effects were maintained until the 30th day. AT reverses AR after 15 days and this effect is preceded by the inhibition of leukocyte migration and occurs simultaneously with the reduction in the expression of inflammatory mediators and AR inducers.

Phellinus linteus Extract Exerts Anti-asthmatic Effects by Suppressing NF-κB and p38 MAPK Activity in an OVA-induced Mouse Model of Asthma.

Phellinus linteus has been used as a traditional herbal medicine in Asian countries and is known to have anti-tumor, immunomodulatory, anti-inflammatory, and anti-allergic activities. However, the protective effects of P. linteus against experimental asthma have not been fully investigated. The objective of this study was to determine whether P. linteus ethanol extract (PLE) suppresses inflammatory response in an OVA-induced asthma model. As expected, the oral administration of PLE significantly inhibited eosinophilic airway inflammation and airway hyperresponsiveness in OVA-challenged BALB/c mice. Supporting these data, the augmentation of Th2 cytokines (IL-4, IL-5, and IL-13), eotaxin, and adhesion molecules in lung tissues and bronchoalveolar lavage fluid after OVA inhalation was markedly attenuated by PLE. Furthermore, PLE reduced OVA-induced activation of NF-κB and p38 MAPK in lung tissues. Therefore, our results suggest the potential of P. linteus as a therapeutic agent for asthma.

TLR-2 Activation Induces Regulatory T Cells and Long-Term Suppression of Asthma Manifestations in Mice

Asthma is a chronic inflammatory disease of the airways characterized by variable airway obstruction and airway hyperresponsiveness (AHR). The T regulatory (Treg) cell subset is critically important for the regulation of immune responses. Adoptive transfer of Treg cells has been shown to be sufficient for the suppression of airway inflammation in experimental allergic asthma. Intervention strategies aimed at expanding the Treg cell population locally in the airways of sensitized individuals are therefore of high interest as a potential therapeutic treatment for allergic airway disease. Here, we aim to test whether long-term suppression of asthma manifestations can be achieved by locally expanding the Treg cell subset via intranasal administration of a TLR-2 agonist. To model therapeutic intervention aimed at expanding the endogenous Treg population in a sensitized host, we challenged OVA-sensitized mice by OVA inhalation with concomitant intranasal instillation of the TLR-2 agonist Pam3Cys, followed by an additional series of OVA challenges. Pam3Cys treatment induced an acute but transient aggravation of asthma manifestations, followed by a reduction or loss of AHR to methacholine, depending on the time between Pam3Cys treatment and OVA challenges. In addition, Pam3Cys-treatment induced significant reductions of eosinophils and increased numbers of Treg cells in the lung infiltrates. Our data show that, despite having adverse acute effects, TLR2 agonist treatment as a therapeutic intervention induces an expansion of the Treg cell population in the lungs and results in long-term protection against manifestation of allergic asthma upon subsequent allergen provocation. Our data indicate that local expansion of Tregs in allergic airway disease is an interesting therapeutic approach that warrants further investigation.

Insulin-like Growth Factor-binding Protein-3 (IGFBP-3) Blocks the Effects of Asthma by Negatively Regulating NF-κB Signaling through IGFBP-3R-mediated Activation of Caspases

Insulin-like growth factor-binding protein-3 (IGFBP-3) is a multifunctional protein known for modulating mitogenic and metabolic actions of IGFs as well as exerting a variety of biological actions not involving IGFs. Here, we show that IGFBP-3 blocks specific physiological consequences of asthma in an IGF-independent manner in vitro and in vivo. IGFBP-3 treatment effectively reduced all physiological manifestations of asthma examined in vivo (airway hyper-responsiveness, cellular and pathological changes in bronchoalveolar lavage fluid and lung tissue, and expression of numerous proinflammatory molecules). These unique IGFBP-3 effects were further confirmed in IGFBP-3-transgenic mice, thus strengthening the notion of IGFBP-3 actions within the respiratory system. Using human epithelial cells, we demonstrated the following: 1) IGFBP-3 blocks TNF-α-induced expression of proinflammatory molecules; 2) IGFBP-3 attenuates the TNF-α-induced migratory response of eosinophils; and 3) IGFBP-3 negatively regulates TNF-α-induced expression of the key NF-κB regulatory molecules IκBα and p65-NF-κB at the post-translational level. We identified that IGFBP-3 degrades IκBα and p65-NF-κB proteins through IGFBP-3 receptor (IGFBP-3R)-mediated activation of caspases thereby inhibiting TNF-α-induced activation of NF-κB signaling cascades. This unique IGFBP-3/IGFBP-3R action was further confirmed by demonstrating complete inhibition of IGFBP-3 action in the presence of caspase inhibitors as well as IGFBP-3R siRNAs. Non-IGF-binding IGFBP-3 mutants further proved the IGF-independent action of IGFBP-3. Our findings indicate that IGFBP-3 inhibits airway inflammation and hyper-responsiveness via an IGF-independent mechanism that involves activation of IGFBP-3R signaling and cross-talk with NF-κB signaling. The IGFBP-3/IGFBP-3R system therefore plays a pivotal role in the pathogenesis of asthma and can serve as a newly identified potential therapeutic target for this debilitating disease.

HIF‐1α inhibition ameliorates an allergic airway disease via VEGF suppression in bronchial epithelium

Hypoxia-inducible factor-1α (HIF-1α) plays a critical role in immune and inflammatory responses. One of the HIF-1α target genes is vascular endothelial growth factor (VEGF), which is a potent stimulator of inflammation, airway remodeling, and physiologic dysregulation in allergic airway diseases. Using OVA-treated mice and murine tracheal epithelial cells, the signaling networks involved in HIF-1α activation and the role of HIF-1α in the pathogenesis of allergic airway disease were investigated. Transfection of airway epithelial cells with HIF-1α siRNA suppressed VEGF expression. In addition, the increased levels of HIF-1α and VEGF in lung tissues after OVA inhalation were substantially decreased by an HIF-1α inhibitor, 2-methoxyestradiol. Our data also show that the increased numbers of inflammatory cells, increased airway hyperresponsiveness, levels of IL-4, IL-5, IL-13, and vascular permeability in the lungs after OVA inhalation were significantly reduced by 2-methoxyestradiol or a VEGF inhibitor, CBO-P11. Moreover, we found that inhibition of the PI3K p110δ isoform (PI3K-δ) or HIF-1α reduced OVA-induced HIF-1α activation in airway epithelial cells. These findings indicate that HIF-1α inhibition may attenuate antigen-induced airway inflammation and hyperresponsiveness through the modulation of vascular leakage mediated by VEGF, and that PI3K-δ signaling may be involved in the allergen-induced HIF-1α activation.

Peroxisome Proliferator-Activated Receptor γ Agonist Down-Regulates IL-17 Expression in a Murine Model of Allergic Airway Inflammation

Peroxisome proliferator-activated receptor gamma (PPARgamma) plays a critical role in the control of airway inflammation. Recently, IL-17 has been found to be implicated in many immune and inflammatory responses, including airway inflammation. However, no data are available concerning the effect of PPARgamma on IL-17 production in airway inflammatory diseases. In this study, we used a mouse model of asthma to evaluate the effect of two PPARgamma agonists, rosiglitazone or pioglitazone, on IL-17 expression in allergic airway disease. After OVA inhalation, mice developed the typical pathophysiological features of asthma, and the expression of IL-17 protein and mRNA in the lungs was increased. Administration of rosiglitazone or pioglitazone reduced the pathophysiological features of asthma and decreased the increased IL-17 protein and mRNA expression after OVA inhalation. In addition, the attenuating effect of PPARgamma agonist on allergic airway inflammation and bronchial hyperresponsiveness is abrogated by coadministration of rIL-17. This study also showed that the inhibition of IL-17 activity with anti-IL-17 Ab remarkably reduced the increased numbers of inflammatory cells of the airways, airway hyperresponsiveness, and the increased levels of IL-4, IL-5, and IL-13 in bronchoalveolar lavage fluid and OVA-specific IgE in serum. In addition, we found that administration of rosiglitazone or pioglitazone decreased the increased NF-kappaB activity and that a NF-kappaB inhibitor, BAY 11-7085, substantially reduced the increased IL-17 protein levels in the lung tissues after OVA inhalation. These findings suggest that the therapeutic effect of PPARgamma in asthma is partly mediated by regulation of IL-17 expression via NF-kappaB pathway.

PGI2, and its analog iloprost, regulate CD4+ Th2 lung inflammation and B cell production of IgE (140.11)

Abstract Our previous findings have shown that PGI2 plays an important role in regulating Th2-mediated lung inflammation. Here, we have examined the mechanism by which PGI2, and its analog iloprost, limit allergic inflammation and the IgE response. Effector DO11.10 CD4+ Th2 cells, generated in the presence of the iloprost, produced normal levels of IL-4 and IL-5, but expressed higher levels of ICOS and CD62L than untreated Th2 cells. Adoptive transfer of iloprost-treated Th2 cells into BALB/c mice caused a markedly reduced airway inflammation following OVA inhalation, compared to untreated Th2 cells. CFSE labeling of CD4+ Th2 cells prior to injection revealed that the iloprost-treated cells proliferated less effectively in vivo in response to inhaled OVA. Moreover, intranasal instillation of FITC-OVA showed that iloprost-treated Th2 cells were less effective at promoting dendritic cell migration to the draining lymph nodes and subsequent expansion OVA-specific T cells. These effects were confirmed using mice lacking the IP receptor for PGI2 (IPKO). Following OVA aerosol challenge, primed IPKO mice developed increased eosinophilic inflammation, with elevated levels of airway CD4+ T cells and serum levels of OVA-specific IgE, compared to WT mice. Collectively, these data demonstrate that generation of PGI2, during allergic lung inflammation serves to limit both Th2 cell expansion and IgE production by B cells. A critical role for IL-4 in promoting expression of PGI2 receptor, IP, on Th2 cells and B cells that produce IgE is proposed.

Lung Th17 inflammatory responses augment polymeric immunoglobulin receptor expression by the airway epithelium and promote B cell recruitment and increase in secretory IgA levels (39.10)

Abstract Polymeric immunoglobulin receptor (pIgR) is a central player in mucosal immunity that mediates delivery of polymeric IgA and IgM to the apical surface via transcytosis across the type I mucosal epithelium. Emerging evidence suggests that Th17 cells, characterized by their production of IL-17, not only mediate autoimmunity but also play key roles in mucosal host defense against extracellular microbes. We demonstrate that adoptive transfer of OVA-specific CD4+ Th17 cells into BALB/c mice, in addition to causing neutrophilic inflammation, mediated a pronounced influx of CD19+ B cells into the lungs following OVA inhalation. Coincident with the cellular recruitment, were the striking elevation in pIgR expression by the airway epithelium and the subsequent increase in IgM and secretory IgA levels. Intranasal administration of IL-17 revealed a key role for this cytokine in the upregulation of pIgR expression by the epithelium. Lung mucosal Th17 responses were markedly regulated by the transfer of antigen-specific CD4+CD25+Foxp3+ regulatory T cells whose suppressive function was restricted to the site of inflammation. These findings support a key role for IL-17-producing Th17 cells in mediating pulmonary immune defense against respiratory pathogens by promoting the expression of pIgR and subsequent transport of mucosal IgA and IgM into the airway lumen.

Detection of allergen-induced airway hyperresponsiveness in isolated mouse lungs

Airway hyperresponsiveness (AHR) is a hallmark of bronchial asthma. Important features of this exaggerated response to bronchoconstrictive stimuli have mostly been investigated in vivo in intact animals or in vitro in isolated tracheal or bronchial tissues. Both approaches have important advantages but also certain limitations. Therefore, the aim of our study was to develop an ex vivo model of isolated lungs from sensitized mice for the investigation of airway responsiveness (AR). BALB/c mice were sensitized by intraperitoneal ovalbumin (Ova) and subsequently challenged by Ova inhalation. In vivo AR was measured in unrestrained animals by whole body plethysmography after stimulation with aerosolized methacholine (MCh) with determination of enhanced pause (P(enh)). Twenty-four hours after each P(enh) measurement, airway resistance was continuously registered in isolated, perfused, and ventilated lungs on stimulation with inhaled or intravascular MCh or nebulized Ova. In a subset of experiments, in vivo AR was additionally measured in orotracheally intubated, spontaneously breathing mice 24 h after P(enh) measurement, and lungs were isolated further 24 h later. Isolated lungs of allergen-sensitized and -challenged mice showed increased AR after MCh inhalation or infusion as well as after specific provocation with aerosolized allergen. AR was increased on days 2 and 5 after Ova challenge and had returned to baseline on day 9. AHR in isolated lungs after aerosolized or intravascular MCh strongly correlated with in vivo AR. Pretreatment of isolated lungs with the beta(2)-agonist fenoterol diminished AR. In conclusion, this model provides new opportunities to investigate mechanisms of AHR as well as pharmacological interventions on an intact organ level.

Inhalation Tolerance Is Induced Selectively in Thoracic Lymph Nodes but Executed Pervasively at Distant Mucosal and Nonmucosal Tissues

Under immunogenic conditions, both the site of initial Ag exposure and consequent T cell priming in specific draining lymph nodes (LNs) imprint the ensuing immune response with lasting tissue-selective tropism. With respect to immune tolerance, whether the site of tolerance induction leads to compartmentalized or, alternatively, pervasive tolerance has not been formally investigated. Using a murine model of inhalation tolerance, we investigated whether the induction of respiratory mucosal tolerance precludes the development of de novo Th2 sensitization upon subsequent exposure to the same Ag at distant mucosal (gut) and nonmucosal (cutaneous) sites. By tracking the proliferation of CFSE-labeled OVA-TCR transgenic CD4(+) T cells upon OVA inhalation in vivo, we defined the site of tolerance induction to be restricted to the thoracic LNs. Expectedly, inhalation tolerance prevented de novo Th2 sensitization upon subsequent exposure to the same Ag at the same site. Importantly, although gut- and skin-draining LNs were not used during tolerance induction, de novo Ag-specific proliferation and Th2 differentiation in these LNs, as well as memory/effector Th2 responses in the gut (allergic diarrhea) and skin (late-phase cutaneous responses) were inhibited upon immunogenic challenge to the same Ag. Interestingly, this pervasive tolerogenic phenotype was not associated with the presence of suppressive activity throughout the lymphatics; indeed, potent suppressive activity was detected solely in the spleen. These data indicate that while inhalation tolerance is selectively induced in local thoracic LNs, its tolerogenic activity resides systemically and leads to pervasive immune tolerance in distant mucosal and nonmucosal sites.

Involvement of PTEN in airway hyperresponsiveness and inflammation in bronchial asthma

Phosphatase and tensin homologue deleted on chromosome ten (PTEN) is part of a complex signaling system that affects a variety of important cell functions. PTEN blocks the action of PI3K by dephosphorylating the signaling lipid phosphatidylinositol 3,4,5-triphosphate. We have used a mouse model for asthma to determine the effect of PI3K inhibitors and PTEN on allergen-induced bronchial inflammation and airway hyperresponsiveness. PI3K activity increased significantly after allergen challenge. PTEN protein expression and PTEN activity were decreased in OVA-induced asthma. Immunoreactive PTEN localized in epithelial layers around the bronchioles in control mice. However, this immunoreactive PTEN dramatically disappeared in allergen-induced asthmatic lungs. The increased IL-4, IL-5, and eosinophil cationic protein levels in bronchoalveolar lavage fluids after OVA inhalation were significantly reduced by the intratracheal administration of PI3K inhibitors or adenoviruses carrying PTEN cDNA (AdPTEN). Intratracheal administration of PI3K inhibitors or AdPTEN remarkably reduced bronchial inflammation and airway hyperresponsiveness. These findings indicate that PTEN may play a pivotal role in the pathogenesis of the asthma phenotype.

Involvement of PTEN in airway hyperresponsiveness and inflammation in bronchial asthma.

Phosphatase and tensin homologue deleted on chromosome ten (PTEN) is part of a complex signaling system that affects a variety of important cell functions. PTEN blocks the action of PI3K by dephosphorylating the signaling lipid phosphatidylinositol 3,4,5-triphosphate. We have used a mouse model for asthma to determine the effect of PI3K inhibitors and PTEN on allergen-induced bronchial inflammation and airway hyperresponsiveness. PI3K activity increased significantly after allergen challenge. PTEN protein expression and PTEN activity were decreased in OVA-induced asthma. Immunoreactive PTEN localized in epithelial layers around the bronchioles in control mice. However, this immunoreactive PTEN dramatically disappeared in allergen-induced asthmatic lungs. The increased IL-4, IL-5, and eosinophil cationic protein levels in bronchoalveolar lavage fluids after OVA inhalation were significantly reduced by the intratracheal administration of PI3K inhibitors or adenoviruses carrying PTEN cDNA (AdPTEN). Intratracheal administration of PI3K inhibitors or AdPTEN remarkably reduced bronchial inflammation and airway hyperresponsiveness. These findings indicate that PTEN may play a pivotal role in the pathogenesis of the asthma phenotype.

Development of a Respiratory Allergy Model in Male Brown Norway Rats: Pulmonary Immune and Gene Expression Studies

The aim of these studies is to develop a respiratory allergy model in Brown Norway (BN) rats using ovalbumin (Ova) as the antigenic stimulus. Specifically, we are interested in studying the mechanisms underlying the development of pulmonary T helper type 2 (Th2) responses following Ova sensitization and inhalation challenge. We have previously reported on the development of an active pulmonary inflammatory response characterized by the presence of eosinophils and measurement of serum immunoglobulin E levels in Ova-sensitized but not in alum-treated, Ova-challenged or sham control rats. In the current study, we have used cDNA microarray technology to assess the gene expression in tracheobronchial, mesenteric and submaxillary lymph nodes, as well as in pulmonary cells and tissues of Ova-sensitized, alum-sensitized or sham control BN rats. Preliminary cDNA microarray results of lung tissue from BN rats exposed to ova–ova (Ova-sensitized, Ova-challenged) 4 or 24 h after ova challenge did not show up-regulation (relative to sham controls) of mRNA for interleukin-4 (IL-4) or IL-5 but did show up-regulation of eotaxin (4 h), intercellular adhesion molecules (ICAM) and vascular cell adhesion molecules (VCAMs), which are likely to be prerequisites for eosinophilic pulmonary inflammatory responses measured at 24 and 48 h post Ova inhalation exposure. In addition, reverse transcriptase–polymerase chain reaction analysis of lung tissue from BN rats exposed to ova–ova 4 and 24 h after challenge demonstrated up-regulation of mRNA for IL-10 (Th2 response). Studies are ongoing to identify the time course and anatomic location of Th2 responses related to the development of Ova-induced respiratory allergy responses in BN rats.

A key role for prostaglandin I2 in limiting lung mucosal Th2, but not Th1, responses to inhaled allergen.

The cellular events that serve to regulate lung mucosal Th2 responses and limit allergic inflammatory reactions are unclear. Using the DO11.10 TCR transgenic mouse, we developed a model of T cell-mediated pulmonary inflammation and demonstrated that high levels of PGI(2) are produced in the airways following OVA inhalation. Selective inhibition of cyclooxygenase-2 in vivo specifically reduced PGI(2) synthesis and resulted in a marked increase in Th2-mediated, but not Th1-mediated, lung inflammation. The elevated Th2-mediated inflammatory response elicited by the cyclooxygenase-2 inhibitor was associated with enhanced airway hyperreactivity and was coincident with a marked increase in the levels of IL-4, IL-5, and IL-13 in the airways, but a reduction in IL-10 production. In keeping with these observations, we found that the mRNA for the PGI(2) receptor was expressed by Th2, but not Th1, cells, and transcripts for the PGI(2) receptor were induced by IL-4 and OVA peptide stimulation. Interestingly, treatment with PGI(2) or its stable analog, carbaprostacyclin, augmented IL-10 production by Th2 cells. Collectively, our findings reveal a key role for PGI(2) in differentially limiting Th2 responses, possibly by promoting production of the immunosuppressive cytokine IL-10 at the site of allergic lung inflammation. These results indicate an important role for prostanoids generated during inflammation in regulating mucosal T cell responses and highlight a potential risk in the use of cyclooxygenase-2-specific inhibitors by allergic asthmatics.

Effect of microbial heat shock proteins on airway inflammation and hyperresponsiveness.

Microbial heat shock proteins (hsp) have been associated with the generation and induction of Th1-type immune responses. We tested the effects of treatment with five different microbial hsp (Mycobacterium leprae, Streptococcus pneumoniae, Helicobacter pylori, bacillus Calmette-Guérin, and Mycobacterium tuberculosis) in a murine model of allergic airway inflammation and airway hyperresponsiveness (AHR). Mice were sensitized to OVA by i.p. injection and then challenged by OVA inhalation. Hsp were administered to each group by i.p. injection before sensitization and challenge. Sensitized and challenged mice developed increased serum levels of OVA-specific IgE with significant airway eosinophilia and heightened responsiveness to methacholine when compared with nonsensitized animals. Administration of M. leprae hsp prevented both development of AHR as well as bronchoalveolar lavage fluid eosinophilia in a dose-dependent manner. Treatment with M. leprae hsp also resulted in suppression of IL-4 and IL-5 production in bronchoalveolar lavage fluid, while IL-10 and IFN-gamma production were increased. Furthermore, M. leprae hsp treatment significantly suppressed OVA-specific IgE production and goblet cell hyperplasia/mucin hyperproduction. In contrast, treatment with the other hsp failed to prevent changes in airway responsiveness, lung eosinophilia, or cytokine production. Depletion of gamma/delta T lymphocytes before sensitization and challenge abolished the effect of M. leprae hsp treatment on AHR. These results indicate selective and distinctive properties among the hsp, and that M. leprae hsp may have a potential therapeutic role in the treatment of allergic airway inflammation and altered airway function.

A Critical Role for Mouse CXC Chemokine(s) in Pulmonary Neutrophilia During Th Type 1-Dependent Airway Inflammation

Ag-specific Th1 and Th2 cells have been demonstrated to play a critical role in the induction of allergic diseases. Here we have investigated the precise mechanisms of Th1-induced airway inflammation. Airway inflammation was induced in BALB/c mice by transfer of freshly induced OVA-specific Th1 or Th2 cells followed by OVA inhalation. In this model, both Th1 and Th2 cells induced airway inflammation. The former induced neutrophilia in airways, whereas the latter induced eosinophilia. Moreover, we found that Th1 cells induced more severe airway hyperresponsiveness (AHR) than Th2 cells. The eosinophilia induced by Th2 cell infusion was almost completely blocked by administration of anti-IL-5 mAb, but not anti-IL-4 mAb. In contrast, Th1-induced AHR and pulmonary neutrophilia were inhibited by the administration of anti-human IL-8R Ab, which blocks the function of mouse CXC chemokine(s). These findings reveal a critical role of mouse CXC chemokine(s) in Th1-dependent pulmonary neutrophilia and AHR.

Dichotomous effect of a traditional Japanese medicine, Bu-zhong-yi-qi-tang on allergic asthma in mice

To determine the potentiality of prophylactic and/or therapeutic approaches using a traditional herbal medicine, Bu-zhong-yi-qi-tang (Japanese name: Hochu-ekki-to, HOT), for the control of allergic disease, we examined the effects of oral administration of HOT on a murine model of asthma allergic responses. When oral administration of HOT was begun at the induction phase immediately after OVA sensitization, eosinophilia and Th2-type cytokine production in the airway were reduced in OVA-sensitized mice following OVA inhalation. The serum levels of OVA-specific immunoglobulin (Ig)E and IgG 1 were significantly decreased, whereas the level of OVA-specific IgG 2a was increased. Interleukin (IL)-4 production by spleen T cells in response to OVA was significantly suppressed, while Interferon (IFN)-γ production was increased in mice treated with HOT in the induction phase. On the other hand, HOT given in the eliciting phase induced a predominant Th2 response with increased IgE production in OVA-sensitized mice following OVA inhalation. These results suggest that the oral administration of HOT dichotomously modulates allergic inflammation in a murine model for asthma, thus offering a different approach for the treatment of allergic disorders.

Overexpression of IL-15 in vivo enhances Tc1 response, which inhibits allergic inflammation in a murine model of asthma.

IL-15, a pleiotropic cytokine, is involved in the inflammatory responses in various infectious and autoimmune diseases. We have recently constructed IL-15-transgenic (Tg) mice, which have an increased number of memory-type CD8+ T cells in the peripheral lymphoid tissues. In the present study, we found that eosinophilia and Th2-type cytokine production in the airway were severely attenuated in OVA-sensitized IL-15-Tg mice following OVA inhalation. IL-15-Tg mice preferentially developed Tc1 responses mediated by CD8+ T cells after OVA sensitization, and in vivo depletion of CD8+ T cells by anti-CD8 mAb aggravated the allergic airway inflammation in IL-15-Tg mice following OVA inhalation. Adoptive transfer of CD8+ T cells from OVA-sensitized IL-15-Tg mice into normal mice before OVA sensitization suppressed Th2 response to OVA in the normal mice. These results suggest that overexpression of IL-15 in vivo suppresses Th2-mediated-allergic airway response via induction of CD8+ T cell-mediated Tc1 response.

Systemic administration of immunostimulatory DNA sequences mediates reversible inhibition of Th2 responses in a mouse model of asthma.

This study investigated whether immunostimulatory DNA sequences (ISS) induce a transient or sustained inhibition of Th2 responses to inhaled antigen. We sensitized mice with subcutaneous injections to develop a Th2 response to ovalbumin (ova) and then administered a dose of ISS prior to ova inhalation challenge. Mice were then rechallenged with ova by inhalation a second time at varying time points after the first ova inhalation (1 to 8 weeks later) to determine whether the ISS dose administered prior to the first ova inhalation protected against a subsequent second ova inhalation challenge. A single dose of ISS inhibited the Th2 response to the first inhalation of ova antigen, as well as 4 weeks later to the second inhalation of ova. However, ISS did not inhibit a Th2 response to the second inhalation of ova 8 weeks later. The reversible inhibition of Th2 responses at 8 weeks suggests the need for repeated ISS administration at monthly intervals.