IL-10-treated dendritic cells decrease airway hyperresponsiveness and airway inflammation in mice

BACKGROUND: IL-10 affects dendritic cell (DC) function, but the effects on airway hyperresponsiveness (AHR) and inflammation are not defined. OBJECTIVE: We sought to determine the importance of IL-10 in regulating DC function in allergen-induced AHR and airway inflammation. METHODS: DCs were generated from bone marrow in the presence or absence of IL-10. In vivo IL-10-treated DCs from IL-10(+/+) and IL-10(-/-) donors pulsed with ovalbumin (OVA) were transferred to naive or sensitized mice before challenge. In recipient mice AHR, cytokine levels, cell composition of bronchoalveolar lavage (BAL) fluid, and lung histology were monitored. RESULTS: In vitro, IL-10-treated DCs expressed lower levels of CD11c, CD80, and CD86; expressed lower levels of IL-12; and suppressed T(H)2 cytokine production. In vivo, after transfer of OVA-pulsed IL-10-treated DCs, naive mice did not have AHR, airway eosinophilia, T(H)2 cytokine increase in BAL fluid, or goblet cell metaplasia when challenged, and in sensitized and challenged mice IL-10-treated DCs suppressed these responses. Levels of IL-10 in BAL fluid and numbers of lung CD4(+)IL-10(+) T cells were increased in mice that received OVA-pulsed IL-10-treated DCs. Transfer of IL-10-treated DCs from IL-10-deficient mice were ineffective in suppressing the responses in sensitized and challenged mice. CONCLUSIONS: These data demonstrate that IL-10-treated DCs are potent suppressors of the development of AHR, inflammation, and T(H)2 cytokine production; these regulatory functions are at least in part through the induction of endogenous (DC) production of IL-10. CLINICAL IMPLICATIONS: Modification of DC function by IL-10 can attenuate lung allergic responses, including the development of AHR.     

STAT6-mediated signaling in Th2-dependent allergic asthma: critical role for the development of eosinophilia, airway hyper-responsiveness and mucus hypersecretion, distinct from its role in Th2 differentiation

When wild-type BALB/c mice were transferred with OVA-specific Th2 cells followed by OVA inhalation, a severe eosinophilia, mucus hypersecretion and airway hyper-responsiveness (AHR) was induced in parallel with a marked elevation of IL-4, IL-5 and IL-13 levels in bronchoalveolar lavage fluid (BALF). However, neither eosinophilia, AHR nor mucus hypersecretion was induced in Th2 cell-transferred STAT6-/- mice. The failure of eosinophilia was not due to the defect of Th2 cytokine production in BALF of STAT6-/- mice transferred with Th2 cells, but because of the defect of STAT6-dependent eotaxin production. Indeed, intranasal administration of eotaxin reconstituted pulmonary eosinophilia but not AHR and mucus hypersecretion in OVA-inhalated STAT6-/- mice. These results initially provided direct evidence that STAT6-dependent eotaxin production is essential for pulmonary eosinophilia. We also dissociated the role of STAT6 for eosinophilia from that for AHR and mucus hypersecretion. Thus, STAT6 also plays a critical role at late phase of Th2-dependent allergy induction.     

Airway hyperresponsiveness in the absence of CD4+ T cells after primary but not secondary challenge

CD4+ T cells have been shown to play a role in the development of airway hyperresponsivness (AHR) and airway eosinophilia in mice using ablation as well as adoptive transfer experiments. However, as other T cell subsets (CD8, NKT) may play a role in these models, we examined the responses of sensitized CD4-deficient mice after either primary or secondary airway allergen challenge. After sensitization, CD4-deficiency in mice was not associated with airway eosinophilia, allergen-specific IgE, or elevated levels of interleukin (IL)-4 or IL-13. Increases in lung CD8 T cells and IL-5 were observed and shown to be essential for AHR as demonstrated after CD8 T cell depletion or anti-IL-5 treatment. In contrast to the response of sensitized CD4-deficient mice to primary allergen challenge, they failed to develop AHR after secondary allergen challenge. Although the importance of this CD4+ T cell-independent pathway in normal mice is unclear at this time, these studies identify the diversity of the cellular pathway, which may contribute to the development of AHR after primary allergen exposure of sensitized mice.     

Effect of anti-mIL-9 antibody on the development of pulmonary inflammation and airway hyperresponsiveness in allergic mice.

Interleukin (IL)-9 is a T-cell-derived cytokine with pleiotropic activities on T helper 2 cells, B cells, and mast cells. IL-9 may therefore play an important role in the development of allergic pulmonary inflammatory diseases. In this study, an antimouse IL-9 (anti-mIL-9) antibody (Ab) was evaluated against pulmonary eosinophilia, histopathologic changes in lung tissues, serum immunoglobulin (Ig) E levels, and airway hyperresponsiveness (AHR) to methacholine in mice sensitized and challenged with ovalbumin (OVA). Additionally, steady-state levels of IL-4, IL-5, IL-13, and interferon-gamma messenger RNA (mRNA) in the lungs were measured. The anti-mIL-9 Ab (200 microg/mouse, intraperitoneally) was given as either four doses during the sensitization period or as a single dose before OVA challenge. Sensitized mice challenged with OVA displayed marked pulmonary eosinophilia, epithelial damage, and goblet cell hyperplasia. OVA challenge also increased mRNA levels of IL-4, IL-5, and IL-13 in the lungs. AHR was also increased twofold in sensitized, challenged mice. Treatment of sensitized, challenged mice with four doses of anti-mIL-9 Ab significantly reduced pulmonary eosinophilia, serum IgE levels, goblet cell hyperplasia, airway epithelial damage, and AHR, but had no effect on IL-4, IL-5, and IL-13 mRNA levels in the lungs. A single dose of the antibody was ineffective on all measures. These results indicate that an antibody to mIL-9 inhibits the development of allergic pulmonary inflammation and AHR in mice.     

Eotaxin-1-deficient mice develop airway eosinophilia and airway hyperresponsiveness.

BACKGROUND: The accumulation of eosinophils in the lung is a hallmark of asthma. In addition to cytokines such as IL-5 which are essential, chemokines have been implicated in the recruitment of eosinophils to the airway. In particular, eotaxin has been shown to be a selective and potent eosinophil chemoattractant, important in the pathogenesis of allergic disease. The goal of the present study was to define the role of eotaxin-1 in the development of allergen-induced eosinophilic airway inflammation and airway hyperresponsiveness (AHR) to inhaled methacholine (MCh). METHODS: Eotaxin-1-deficient mice were sensitized and exposed to a single challenge with allergen. Airway function and airway and tissue as well as peripheral blood and bone marrow eosinophilia were examined 18 and 48 h after the last challenge. RESULTS: Following allergen sensitization and challenge, eotaxin-1-deficient mice developed levels of AHR to inhaled MCh at 18 and 48 h comparable to controls. Further, levels of bronchoalveolar lavage (BAL) and tissue eosinophilia at the same time points were comparable in the two strains of mice. Tissue eosinophilia, assessed by quantitating major basic protein staining cells, preceded BAL eosinophilia in a similar manner. Bone marrow and peripheral blood eosinophilia were unimpaired in deficient mice. CONCLUSION: The results demonstrate that the major eotaxin, eotaxin-1 is not essential for the development of airway eosinophilia or AHR, implying that other chemokines, alone or in combination, can overcome this deficiency.     

Contribution of IL-18-induced innate T cell activation to airway inflammation with mucus hypersecretion and airway hyperresponsiveness

Human bronchial asthma is characterized by airway hyperresponsiveness (AHR), eosinophilic airway inflammation, mucus hypersecretion and high serum level of IgE. IL-18 was originally regarded to induce T(h)1-related cytokines from Th1 cells in the presence of IL-12. However, our previous reports clearly demonstrated that IL-18 with IL-2 promotes Th2 cytokines production from T cells and NK cells. Furthermore, IL-18 with IL-3 stimulates basophils and mast cells to produce Th2 cytokines. Thus, we examined the capacity of IL-2 and IL-18 to induce AHR, airway eosinophilic inflammation and goblet cell metaplasia. Intranasal administration of IL-2 and IL-18 induces AHR, mucus hypersecretion and eosinophilic inflammation in the lungs of naive mice. CD4+ T cells are prerequisite for this IL-2 plus IL-18-induced bronchial asthma, because CD4+ T cells-depleted or Rag-2-deficient (Rag-2-/-) mice did not develop bronchial asthma after IL-2 plus IL-18 treatment. Both STAT6-/- mice and IL-13-neutralized wild-type mice failed to develop AHR, goblet cell metaplasia and airway eosinophilic inflammation, while IL-4-/- mice almost normally developed, suggesting that IL-13 is a major causative factor and IL-4 mainly enhances the degree of AHR and eosinophilic inflammation. Both IL-4 and IL-13 equally induce eotaxin in mouse embryonic fibroblasts. However, only IL-13 blockade inhibited asthma symptoms, suggesting that IL-13 but not IL-4 is produced abundantly and plays a critical role in the pathogenesis of bronchial asthma in this model. As airway epithelial cells store robust IL-18, IL-18 might be critically involved in pathogen-induced bronchial asthma, in which pathogens stimulate epithelial cells to produce IL-18 without IL-12 induction.     

Prior airway exposure to allergen increases virus-induced airway hyperresponsiveness

BACKGROUND: Respiratory syncytial virus (RSV) bronchiolitis in early life can lead to changes in airway function, but there are likely additional predisposing factors, such as prior allergen exposure, determining which children develop wheezing and asthma. OBJECTIVE: To define the effects of prior airway exposure to sensitizing allergen on the development of airway inflammation and hyperresponsiveness (AHR) to subsequent RSV infection. METHODS: BALB/c mice were exposed to ovalbumin or PBS exclusively through the airways and subsequently infected with RSV or sham-inoculated. AHR, lung inflammation, and the frequency of cytokine-producing T lymphocytes in the lung were determined. RESULTS: In PBS-exposed mice, RSV infection induced AHR and an increased proportion of TH1-type (IFN-gamma and IL-12) cytokine-producing cells in the lungs. However, in mice previously exposed to ovalbumin through the airways and subsequently infected with RSV, the degree of AHR was significantly increased and was associated with an increased proportion of TH2 (IL-4, IL-5) cytokine-producing T lymphocytes. This response was also associated with an increased accumulation of eosinophils, neutrophils, and CD8+ T cells in the lungs. CONCLUSIONS: These data suggest that prior airway exposure to allergen may predispose sensitized hosts to a greater degree of altered airway function upon subsequent respiratory viral infection.     

Expression of heme oxygenase-1 and its effects in allergic airway inflammation and hyperresponsiveness]

We investigated whether an expression of hemeoxygenase-1 (HO-1) within the lung tissue is related to allergic airway inflammation and HO-1 expression could influence airway hyperreactivity (AHR) and eosinophilia in C57BL/6 mice actively sensitized to ovalbumin. The number of HO-1 positive cells was increased in the subepithelium of the bronchi after OVA challenge and HO-1 was localized to alveolar macrophage.Zinc-protoporphyrin (Zn-PP), a competitive inhibitor of hemeoxygenase, by intraperitoneal injection clearly inhibited AHR, pulmonary eosinophilia and IL-5 and IL-13 in the lung tissue. These data indicate that the expression of HO-1 is increased within the lung tissue in allergic airway inflammation and the overexpression of HO-1 could enhanced allergic airway inflammation.     

Development of eosinophilic airway inflammation and airway hyperresponsiveness requires interleukin-5 but not immunoglobulin E or B lymphocytes.

We previously defined a role for B cells and allergen-specific immunoglobulins in the development of allergic sensitization, airway inflammation, and airway hyperresponsiveness (AHR), using a 10-d protocol in which allergen exposure occurred exclusively via the airways, without adjuvant. In the present protocol, normal and B-cell-deficient (microMt(-/-)) mice were sensitized intraperitoneally to ovalbumin (OVA) and challenged with OVA via the airways in order to examine the requirements for AHR with this protocol. T-cell activation (antigen-specific proliferative responses and Th2-type cytokine production) and eosinophil infiltration in the peribronchial regions of the airways, with signs of eosinophil activation and degranulation, occurred in both experimental groups. In contrast to the 10-d protocol, increased in vivo airway responsiveness to methacholine and in vitro tracheal smooth-muscle responses to electrical field stimulation were observed in both normal and B-cell-deficient mice, and these responses were inhibited by anti-interleukin (IL)-5 administration before airway challenge. These data show that IL-5, but not B cells or allergen-specific IgE, are required for eosinophil airway infiltration and the development of AHR following allergen/alum sensitization and repeated airway challenge with allergen. These results emphasize that the use of different sensitization and challenge protocols can influence the requirements for development of AHR.     

Reciprocal immunomodulatory effects of gamma interferon and interleukin-4 on filaria-induced airway hyperresponsiveness

Tropical pulmonary eosinophilia (TPE) is a severe asthmatic syndrome of lymphatic filariasis, in which an allergic response is induced to microfilariae (Mf) in the lungs. Previously, in a murine model for TPE, we have demonstrated that recombinant interleukin-12 (IL-12) suppresses pulmonary eosinophilia and airway hyperresponsiveness (AHR) by modulating the T helper (Th) response in the lungs from Th2- to Th1-like, with elevated gamma-interferon (IFN-gamma) production and decreased IL-4 and IL-5 production. The present study examined the immunomodulatory roles of IL-4 and IFN-gamma in filaria-induced AHR and pulmonary inflammation using mice genetically deficient in these cytokines. C57BL/6, IL-4 gene knockout (IL-4(-/-)), and IFN-gamma(-/-) mice were first immunized with soluble Brugia malayi antigens and then inoculated intravenously with 200,000 live Mf. Compared with C57BL/6 mice, IL-4(-/-) mice exhibited significantly reduced AHR, whereas IFN-gamma(-/-) mice had increased AHR. Histopathologically, each mouse strain showed increased cellular infiltration into the lung parenchyma and bronchoalveolar space compared with na?ve animals. However, consistent with changes in AHR, IL-4(-/-) mice had less inflammation than C57BL/6 mice, whereas IFN-gamma(-/-) mice had exacerbated pulmonary inflammation with the loss of pulmonary architecture. Systemically, IL-4(-/-) mice produced significantly higher IFN-gamma levels compared with C57BL/6 mice, whereas IFN-gamma(-/-) mice produced significantly higher IL-4 levels. These data indicate that IL-4 is required for the induction of filaria-induced AHR, whereas IFN-gamma suppresses AHR.     

Transient contribution of mast cells to pulmonary eosinophilia but not to hyper‐responsiveness

BACKGROUND: We have recently demonstrated that the transfer of interleukin (IL)-5-producing CD4+ T cell clones into unprimed mice is sufficient for the development ofeosinophilic inflammation in the bronchial mucosa upon antigen inhalation. OBJECTIVE: The aim of this study was to elucidate the possible contribution of mast cells in eosinophilic inflammation and bronchial hyper-responsiveness (BHR), and to discriminate between the roles of CD4+ T cells and mast cells. METHODS: Mast cell-deficient mice (WBB6F1-W/Wv) and their congenic normal littermates (WBB6F1-+/+) were immunized with ovalbumin and challenged by inhalation with the relevant antigen. RESULTS: Airway eosinophilia was induced with equivalent intensity in +/+ and W/Wv mice 6, 24, 96 and 216 h after antigen inhalation. In contrast, 48 h after antigen challenge, eosinophilic infiltration into the bronchial mucosa was significantly less pronounced in W/Wv mice than in +/+ mice. Anti-CD4 monoclonal antibody (mAb), anti-IL-5 mAb, and cyclosporin A were administered next, demonstrating that the airway eosinophilia of W/Wv mice induced 48 h after antigen challenge was almost completely inhibited by each of these three treatments, but that of +/+ mice was significantly less susceptible. Bronchial responsiveness to acetylcholine was increased 48 h after antigen challenge and was not significantly different between +/+ and W/Wv mice. Administration of anti-IL-5 mAb completely inhibited the development of BHR in both +/+ and W/Wv mice. CONCLUSION: These results indicate that, in mice, mast cells do have a supplemental role in the development of pulmonary eosinophilia but not BHR. CD4+ T cells totally regulate these responses by producing IL-5.     

Prolonged ovalbumin exposure attenuates airway hyperresponsiveness and T cell function in mice

BACKGROUND: Continuous exposure of sensitized mice to an innocuous antigen, such as OVA, does not lead to chronic airway eosinophilia, but induces antigen unresponsiveness and resolution of the inflammatory response. In this study we explored mechanisms underlying attenuation of the airway inflammatory response, assessed whether the phenomenon is strain-specific, and determined its consequences to airway physiology. METHODS: Mice were sensitized and exposed to OVA for two and four weeks. Analysis involved BAL, flow cytometry, adoptive transfer of OVA specific CD4 T cells, ex vivo cytokine expression and response to methacholine challenge. RESULTS: Chronic exposure to antigen resulted in decreased eosinophilia in 5 different mouse strains. Likewise, numbers of lung CD4 T cells expressing activation and Th2 markers sharply declined following continuous OVA exposure. Transfer studies using OVA TcR transgenic cells revealed that the contraction of lung T cells included antigen-specific cells. Systemically, we observed a loss of Th2 memory effector function. Finally, we observed significantly attenuated airway hyper-responsiveness (AHR) in chronically exposed animals. CONCLUSIONS: Attenuation of airway eosinophilia in response to chronic OVA exposure is independent of genetic background. Airway eosinophilia, but not systemic responses, correlates with and is predictive for airway hyperresponsiveness. Our study contributes to the understanding of immune regulatory processes controlling antigen-driven airway inflammatory responses.     

Effects of post‐inhalation treatment with interleukin‐12 on airway hyper‐reactivity, eosinophilia and interleukin‐18 receptor expression in a mouse model of asthma

BACKGROUND: Correcting Th1/Th2 imbalance with administration of IL-12 before and during antigen challenge holds therapeutic promise in asthma. However, the effects of IL-12 on the established asthmatic responses have not fully been examined. OBJECTIVE: We investigated whether IL-12 administered after antigen challenge could diminish airway hyper-reactivity (AHR) and eosinophilia in mice actively sensitized to ovalbumin. We also have investigated the ability of administered IL-12 to induce IL-18 receptor (IL-18R) expression that may lead possible synergic action of IL-12 with endogenous IL-18. METHODS: C57BL/6 mice immunized to ovalbumin (OVA) by intraperitoneal (i.p.) injection, were challenged three times with an aerosol of OVA every second day for 8 days. Recombinant IL-12 (500 ng) was intravenously administered on a single occasion 1 h after the final challenge of mice. Mice were analysed for effects of IL-12 on AHR, inflammatory cell infiltration and cytokine levels in lung tissue as well as serum immunoglobulin (Ig) E levels. Immunohistochemistry for IL-18R was performed using rat monoclonal antibody specific for murine IL-18Ralpha (IL-1 receptor related protein; IL-1Rrp). RESULTS: An intravenous IL-12 administration diminished AHR, pulmonary eosinophilia and T lymphocyte infiltration, serum IgE, IL-4 and IL-13 in lung tissue. Expression of IL-18R was induced in the mononuclear cells in the lung of mice exposed to OVA. IL-12 administration enhanced the IL-18R expression compared with the control. CONCLUSION: These data indicate that IL-12 can attenuate established antigen-induced AHR and inflammation. In this mechanism it would be interpreted as follows: IL-12 administration in OVA-challenged mice decreased IL-4 production and IgE production thereafter through direct effect on inhibiting the activation of established Th2 cells response and also combined effect with up-regulation of IL-18R expression by inflammatory cells in the lung.     

Requirement for chemokine receptor 5 in the development of allergen-induced airway hyperresponsiveness and inflammation

Chemokine receptor (CCR) 5 is expressed on dendritic cells, macrophages, CD8 cells, memory CD4 T cells, and stromal cells, and is frequently used as a marker of T helper type 1 cells. Interventions that abrogate CCR5 or interfere with its ligand binding have been shown to alter T helper type 2-induced inflammatory responses. The role of CCR5 on allergic airway responses is not defined. CCR5-deficient (CCR5(-/-)) and wild-type (CCR5(+/+)) mice were sensitized and challenged with ovalbumin (OVA) and allergic airway responses were monitored 48 hours after the last OVA challenge. Cytokine levels in lung cell culture supernatants were also assessed. CCR5(-/-) mice showed significantly lower airway hyperresponsiveness (AHR) and lower numbers of total cells, eosinophils, and lymphocytes in bronchoalveolar lavage (BAL) fluid compared with CCR5(+/+) mice after sensitization and challenge. The levels of IL-4 and IL-13 in BAL fluid of CCR5(-/-) mice were lower than in CCR5(+/+) mice. Decreased numbers of lung T cells were also detected in CCR5(-/-) mice after sensitization and challenge. Transfer of OVA-sensitized T cells from CCR5(+/+), but not transfer of CCR5(-/-) cells, into CCR5(-/-) mice restored AHR and numbers of eosinophils in BAL fluid after OVA challenge. Accordingly, the numbers of airway-infiltrating donor T cells were significantly higher in the recipients of CCR5(+/+) T cells. Taken together, these data suggest that CCR5 plays a pivotal role in allergen-induced AHR and airway inflammation, and that CCR5 expression on T cells is essential to the accumulation of these cells in the airways.     

CD1d restricted natural killer T cells are not required for allergic skin inflammation

BACKGROUND: Invariant T-cell receptor-positive natural killer (iNKT) cells have been shown to be essential for the development of allergen-induced airway hyperreactivity (AHR). OBJECTIVE: We examined the role of iNKT cells in allergic skin inflammation using a murine model of atopic dermatitis (AD) elicited by epicutaneous sensitization with ovalbumin (OVA). METHODS: Wild-type (WT) and natural killer T-cell-deficient CD1d-/- mice were epicutaneously sensitized with OVA or normal saline and challenged with aerosolized OVA. iNKT cells in skin and bronchoalveolar lavage fluid were analyzed by fluorescence-activated cell sorting, and cytokine mRNA levels were measured by quantitative RT-PCR. AHR to methacholine was measured after OVA inhalation. RESULTS: Skin infiltration by eosinophils and CD4+ cells and expression of mRNA encoding IL-4 and IL-13 in OVA-sensitized skin were similar in WT and CD1d-/- mice. No significant increase in iNKT cells was detectable in epicutaneously sensitized skin. In contrast, iNKT cells were found in the bronchoalveolar lavage fluid from OVA-challenged epicutaneously sensitized WT mice, but not CD1d-/- mice. Epicutaneously sensitized CD1d-/- mice had an impaired expression of IL-4, IL-5, and IL-13 mRNA in the lung and failed to develop AHR in response to airway challenge with OVA. CONCLUSION: These results demonstrate that iNKT cells are not required for allergic skin inflammation in a murine model of AD, in contrast with airway inflammation, in which iNKT cells are essential. CLINICAL IMPLICATIONS: Understanding the potential role of iNKT cells in AD will allow us to have a more specific target for therapeutic use.     

Interleukin (IL)-5 but not immunoglobulin E reconstitutes airway inflammation and airway hyperresponsiveness in IL-4-deficient mice

We studied the role of interleukin (IL)-4, IL-5, and allergen-specific immunoglobulin (Ig) E in the development of allergen-induced sensitization, airway inflammation, and airway hy-perresponsiveness (AHR). Normal, IL-4-, and IL-5-deficient C57BL/6 mice were sensitized intraperitoneally to ovalbumin (OVA) and repeatedly challenged with OVA via the airways. After allergen sensitization and airway challenge, normal and IL-5-deficient, but not IL-4-deficient, mice developed increased serum levels of total and antigen-specific IgE levels and increased IL-4 production in the lung tissue compared with nonsensitized control mice. Only normal mice showed significantly increased IL-5 production in the lung tissue and an eosinophilic infiltration of the peribronchial regions of the airways, whereas both IL-4- and IL-5-deficient mice had little or no IL-5 production and no significant eosinophilic airway inflammation. Associated with the inflammatory responses in the lung, only normal mice developed increased airway responsiveness to methacholine after sensitization and airway challenge; in both IL-4- and IL-5-deficient mice, airway responsiveness was similar to that in nonsensitized control mice. Reconstitution of sensitized, IL-4-deficient mice before allergen airway challenge with IL-5, but not with allergen-specific IgE, restored eosinophilic airway inflammation and the development of AHR. These data demonstrate the importance of IL-4 for allergen-driven airway sensitization and that IL-5, but not allergen-specific IgE, is required for development of eosinophilic airway inflammation and AHR after this mode of sensitization and challenge.     

Respiratory syncytial virus-induced exaggeration of allergic airway disease is dependent upon CCR1-associated immune responses

Severe respiratory syncytial virus (RSV) infection has a significant impact on airway function, and may alter subsequent development of asthma. CCR1 mRNA was significantly up-regulated during primary RSV infection in BALB/c mice, and was also up-regulated during allergen exposure in sensitized mice. Although CCR1(-/-) mice exhibited similar levels of airway hyperresponsiveness (AHR) as wild-type mice in response to cockroach allergen alone, in animals treated with RSV prior to cockroach antigen (CRA) sensitization and challenge, a significant decrease in exacerbated AHR was observed in the CCR1(-/-) mice. The reduction in AHR after RSV and allergen challenge in CCR1(-/-) mice was not associated with changes in peribronchial eosinophilia, but was accompanied by significantly decreased IL-13 levels in the lungs, as well as an absence of mucus cell staining within the airways. When T lymphocyte numbers were compared in animals receiving CRA to animals receiving a combination of RSV and allergen an increase in both CD4 and CD8 T lymphocytes could be detected in wild-type but not CCR1(-/-) animals. Thus, these data suggest that CCR1-mediated responses have a primary role for inducing severe disease during RSV infection, and may be responsible for altering the lung pathophysiological responses to subsequent allergen challenges via IL-13-mediated mechanisms.     

Vgamma1+ T cells and tumor necrosis factor-alpha in ozone-induced airway hyperresponsiveness

gammadelta T cells regulate airway reactivity, but their role in ozone (O3)-induced airway hyperresponsiveness (AHR) is not known. Our objective was to determine the role of gammadelta T cells in O3-induced AHR. Different strains of mice, including those that were genetically manipulated or antibody-depleted to render them deficient in total gammadelta T cells or specific subsets of gammadelta T cells, were exposed to 2.0 ppm of O3 for 3 hours. Airway reactivity to inhaled methacholine, airway inflammation, and epithelial cell damage were monitored. Exposure of C57BL/6 mice to O3 resulted in a transient increase in airway reactivity, neutrophilia, and increased numbers of epithelial cells in the lavage fluid. TCR-delta(-/-) mice did not develop AHR, although they exhibited an increase in neutrophils and epithelial cells in the lavage fluid. Similarly, depletion of gammadelta T cells in wild-type mice suppressed O3-induced AHR without influencing airway inflammation or epithelial damage. Depletion of Vgamma1+, but not of Vgamma4+ T cells, reduced O3-induced AHR, and transfer of total gammadelta T cells or Vgamma1+ T cells to TCR-delta(-/-) mice restored AHR. After transfer of Vgamma1+ cells to TCR-delta(-/-) mice, restoration of AHR after O3 exposure was blocked by anti-TNF-alpha. However, AHR could be restored in TCR-delta(-/-)mice by transfer of gammadelta T cells from TNF-alpha-deficient mice, indicating that another cell type was the source of TNF-alpha. These results demonstrate that TNF-alpha and activation of Vgamma1+ gammadelta T cells are required for the development of AHR after O3 exposure.     

Early interleukin 4-dependent response can induce airway hyperreactivity before development of airway inflammation in a mouse model of asthma

In experimental models of bronchial asthma with mice, airway inflammation and increase in airway hyperreactivity (AHR) are induced by a combination of systemic sensitization and airway challenge with allergens. In this report, we present another possibility: that systemic antigen-specific sensitization alone can induce AHR before the development of inflammation in the airway. Male BALB/c mice were sensitized with ovalbumin (OVA) by a combination of intraperitoneal injection and aerosol inhalation, and various parameters for airway inflammation and hyperreactivity were sequentially analyzed. Bronchial response measured by a noninvasive method (enhanced pause) and the eosinophil count and interleukin (IL)-5 concentration in bronchoalveolar lavage fluid (BALF) gradually increased following the sensitization, and significant increase was achieved after repeated OVA aerosol inhalation along with development of histologic changes of the airway. In contrast, AHR was already significantly increased by systemic sensitization alone, although airway inflammation hardly developed at that time point. BALF IL-4 concentration and the expression of IL-4 mRNA in the lung reached maximal values after the systemic sensitization, then subsequently decreased. Treatment of mice with anti-IL-4 neutralizing antibody during systemic sensitization significantly suppressed this early increase in AHR. In addition, IL-4 gene-targeted mice did not reveal this early increase in AHR by systemic sensitization. These results suggest that an immune response in the lung in an early stage of sensitization can induce airway hyperreactivity before development of an eosinophilic airway inflammation in BALB/c mice and that IL-4 plays an essential role in this process. If this early increase in AHR does occur in sensitized human infants, it could be another therapeutic target for early prevention of the future onset of asthma.