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.

Extensive eosinophil degranulation and peroxidase-mediated oxidation of airway proteins do not occur in a mouse ovalbumin-challenge model of pulmonary inflammation.

Paradigms of eosinophil effector function in the lungs of asthma patients invariably depend on activities mediated by cationic proteins released from secondary granules during a process collectively referred to as degranulation. In this study, we generated knockout mice deficient for eosinophil peroxidase (EPO) to assess the role(s) of this abundant secondary granule protein in an OVA-challenge model. The loss of EPO had no effect on the development of OVA-induced pathologies in the mouse. The absence of phenotypic consequences in these knockout animals extended beyond pulmonary histopathologies and airway changes, as EPO-deficient animals also displayed OVA-induced airway hyperresponsiveness after provocation with methacholine. In addition, EPO-mediated oxidative damage of proteins (e.g., bromination of tyrosine residues) recovered in bronchoalveolar lavage from OVA-treated wild-type mice was <10% of the levels observed in bronchoalveolar lavage recovered from asthma patients. These data demonstrate that EPO activities are inconsequential to the development of allergic pulmonary pathologies in the mouse and suggest that degranulation of eosinophils recruited to the lung in this model does not occur at levels comparable to those observed in humans with asthma.

A murine IL-4 receptor antagonist that inhibits IL-4- and IL-13-induced responses prevents antigen-induced airway eosinophilia and airway hyperresponsiveness.

The closely related Th2 cytokines, IL-4 and IL-13, share many biological functions that are considered important in the development of allergic airway inflammation and airway hyperresponsiveness (AHR). The overlap of their functions results from the IL-4R alpha-chain forming an important functional signaling component of both the IL-4 and IL-13 receptors. Mutations in the C terminus region of the IL-4 protein produce IL-4 mutants that bind to the IL-4R alpha-chain with high affinity, but do not induce cellular responses. A murine IL-4 mutant (C118 deletion) protein (IL-4R antagonist) inhibited IL-4- and IL-13-induced STAT6 phosphorylation as well as IL-4- and IL-13-induced IgE production in vitro. Administration of murine IL-4R antagonist during allergen (OVA) challenge inhibited the development of allergic airway eosinophilia and AHR in mice previously sensitized with OVA. The inhibitory effect on airway eosinophilia and AHR was associated with reduced levels of IL-4, IL-5, and IL-13 in the bronchoalveolar lavage fluid as well as reduced serum levels of OVA-IGE: These observations demonstrate the therapeutic potential of IL-4 mutant protein receptor antagonists that inhibit both IL-4 and IL-13 in the treatment of allergic asthma.

Temporal association between airway hyperresponsiveness and airway eosinophilia in ovalbumin-sensitized mice.

The temporal association between airway inflammation and airway hyperresponsiveness (AHR) has been analyzed in BALB/c mice sensitized to, and subsequently exposed to, a single intranasal challenge of ovalbumin (OVA). In OVA-sensitized/challenged animals only a small increase in responsiveness to methacholine (MCh) was seen at 8 h, peaked at 24 to 48 h, and resolved by 96 h. An early bronchoalveolar lavage fluid (BALF) neutrophil infiltrate (peaking at 8 h postchallenge; approximately 72% total cells was observed) that returned to baseline by 48 h. BALF eosinophil numbers did not increase until 48 h (approximately 32% of total cells), peaked at 96 h (approximately 38% total cells), and remained elevated at 8 d (approximately 27% total cells). Airway tissue eosinophilia preceded changes in BALF. Eosinophil peroxidase (EPO) levels in BALF were elevated in OVA-sensitized/challenged mice at 48 h only. BALF TNF-alpha levels peaked at 8 h, whereas IL-5 and IL-4 levels peaked at 24 h. IL-13 levels were increased at both 24 and 48 h. Mucus-positive cells were not observed in the airway epithelium until 48 h. Administration of IL-5 or VLA-4 antibody prior to OVA challenge prevented the development of AHR in sensitized mice as well as BALF and tissue eosinophilia. These data identify a temporal association between Th2 cytokine production, tissue eosinophil infiltration and activation, and, importantly, both the development and resolution kinetics of AHR. Moreover, the antibody studies further support the association of eosinophilia with the pathogenesis of AHR.

Eosinophil major basic protein-1 does not contribute to allergen-induced airway pathologies in mouse models of asthma.

The relationship between eosinophils and the development of Ag-induced pulmonary pathologies, including airway hyper-responsiveness, was investigated using mice deficient for the secondary granule component, major basic protein-1 (mMBP-1). The loss of mMBP-1 had no effect on OVA-induced airway histopathologies or inflammatory cell recruitment. Lung function measurements of knockout mice demonstrated a generalized hyporeactivity to methacholine-induced airflow changes (relative to wild type); however, this baseline phenotype was observable only with methacholine; no relative airflow changes were observed in response to another nonspecific stimulus (serotonin). Moreover, OVA sensitization/aerosol challenge of wild-type and mMBP-1(-/-) mice resulted in identical dose-response changes to either methacholine or serotonin. Thus, the airway hyper-responsiveness in murine models of asthma occurs in the absence of mMBP-1.

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.

Critical roles for interleukin-4 and interleukin-5 during respiratory syncytial virus infection in the development of airway hyperresponsiveness after airway sensitization.

In mice, respiratory syncytial virus (RSV) infection can enhance the consequences of allergic airway sensitization, resulting in lung eosinophilia and the development of airway hyperresponsiveness (AHR) to inhaled methacholine (MCh). To delineate a role for interleukin-5 (IL-5), interleukin-4 (IL-4), and interferon gamma (IFN-gamma) in mediating the effects of RSV infection on subsequent allergic sensitization, we treated BALB/c mice with anti-IL-5 during acute RSV infection but not during subsequent exposure to ovalbumin (OVA). IL-5-deficient and IL-4-deficient mice were also treated with IL-5 either during acute RSV infection or during the sensitization period. Airway responsiveness to inhaled MCh was assessed and numbers of lung eosinophils were monitored. Anti-IL-5 treatment during RSV infection reduced AHR and lung eosinophilia after subsequent exposure to allergen. In IL-5-deficient or IL-4-deficient mice lung eosinophilia and AHR after RSV infection and allergen exposure were also markedly reduced. IL-5 administration during RSV infection restored the responses to allergen in both IL-5- and IL-4-deficient mice. However, IL-5 administration only during sensitization restored these responses in IL-4-deficient but not in IL-5-deficient animals. IFN-gamma-deficient mice developed AHR and some lung eosinophilia after allergen exposure alone and when RSV infection preceded allergen, these responses were enhanced. We conclude that both IL-5, particularly during acute infection, and IL-4 are critical in mediating the effects of RSV infection on allergic airway sensitization, resulting in the development of AHR and lung eosinophilia.

Assessment of IgE allergen specificity among latex-allergic health care workers: review of IgE-binding components of various latex extracts.

BACKGROUND: Allergic reactions to natural rubber latex have increased during the past 10 years, especially in many health care workers who have high exposure to latex allergens both by direct skin contact and by inhalation of latex particles from powdered gloves. Development of satisfactory diagnostic methods to verify the presence of latex allergy in health care workers requires characterization of the immunoreactive proteins in latex products and identification of specific IgE antibodies in sensitized patients. A number of different latex preparations are now available for in vitro evaluations. OBJECTIVES: Utilizing different in vitro methods, this study examines IgE sensitization to components of latex in a selected population of hospital employees, employing a raw natural latex glove extract and various commercial latex extracts. METHODS: Two hundred hospital employees exposed to latex were evaluated using an allergy history questionnaire. To further identify sensitized patients, two different specific IgE tests and leukocyte histamine release tests were performed using a panel of latex extracts obtained from different manufacturers. Sodium dodecylsulfate polyacrylamide electrophoresis (SDS-PAGE) profiles were obtained. Sera from 34 subjects suspected to be latex-sensitized were IgE immunoblotted to assess the presence of IgE antibodies directed toward specific latex proteins. RESULTS: Thirty-four participants (17%) were considered sensitized to latex by a positive clinical history in conjunction with positive specific IgE tests (18 individuals) and/or positive histamine release tests (26 individuals). Significant extract differences in both the histamine release response profile and the frequency of positive test results were noted in the histamine release test. Significant individual differences in patients' latex epitope-specificity were found by IgE immunoblotting, substantiated by sodium dodecylsulfate polyacrylamide profiles revealing differences in protein band patterns among the various extracts. The IgE immunoblots indicated that the majority of patients reacted to proteins with molecular weights of 14, 21, 30 to 35, and 42 kD; the 30 to 35 kD protein being predominant. Seven subjects (22%) of the 34 considered to be latex-sensitized did not reveal binding of specific IgE in immunoblots. One latex extract (Stallergene) with the widest IgE-reacting protein repertoire identified the majority of subjects (63%) as latex sensitive by leukocyte histamine release and also provided the best quantitative histamine release test results. CONCLUSION: Only by testing with a combination of latex extracts were all sensitized individuals identified. This study demonstrates that currently several in vitro methods may be necessary to detect IgE sensitization to latex. Latex extracts to be employed in future skin tests must contain a wide epitope repertoire of IgE-binding proteins to identify all latex-sensitized individuals.

Transfer of the enhancing effect of respiratory syncytial virus infection on subsequent allergic airway sensitization by T lymphocytes.

In mice, respiratory syncytial virus (RSV) infection enhances allergic airway sensitization, resulting in lung eosinophilia and in airway hyperresponsiveness (AHR). The mechanisms by which RSV contributes to development of asthma and its effects on allergic airway sensitization in mice are not known. We tested whether these consequences of RSV infection can be adoptively transferred by T cells and whether depletion of T cell subsets prevents the effects of RSV infection on subsequent airway sensitization. Mononuclear cells, T lymphocytes, or CD4 or CD8 T cells from peribronchial lymph nodes (PBLN) of RSV-infected mice were transferred into naive BALB/c mice which were then exposed to OVA via the airways. Additionally, RSV-infected mice were depleted of CD4 or CD8 T cells following acute RSV infection but prior to airway sensitization. Following sensitization, airway responsiveness to inhaled methacholine, numbers of lung eosinophils, and levels of IFN-gamma, IL-4, and IL-5 in PBLN cell cultures were monitored. Transfer of T cells from RSV-infected mice resulted in increased eosinophil influx into the lungs, increased IL-5 production, and development of AHR following airway sensitization to allergen. Transfer of CD8 but not CD4 T cells from the PBLN of RSV-infected mice also resulted in AHR following 10 days of OVA exposure. Further, depletion of CD8 T cells prevented these consequences of RSV infection while CD4 T cell depletion reduced them. We conclude that T cells, in particular CD8 T cells, are critical in mediating RSV-induced development of lung eosinophilia and AHR following allergic airway sensitization.

The failure of STAT6-deficient mice to develop airway eosinophilia and airway hyperresponsiveness is overcome by interleukin-5.

While signal transducer and activator of transcription protein 6 (STAT6) is important in interleukin-4 (IL-4)-induced commitment of CD4(+) T cells to the T helper cell, type 2 (Th2) phenotype and IgE isotype switching in B cells, its role in other IL-4-mediated events and their impact upon the allergic response is less evident. In the present study we demonstrate the critical role of STAT6 in the development of allergic airway eosinophilia and airway hyperresponsiveness (AHR) after allergen sensitization and challenge. STAT6-deficient (STAT6-/-) mice did not develop a Th2 cytokine response or an allergen-specific IgE response. Further, STAT6-/- mice had a reduced constitutive and allergen-induced expression of CD23 as well as lower mucus production in the airway epithelium. Critically, we show that IL-5 alone can reconstitute airway eosinophilia and AHR in sensitized and challenged STAT6-/- mice. This emphasizes the essential nature of the IL-4-dependent signaling of T cells to the Th2 phenotype and secretion of IL-5, resulting in the airway eosinophilia and AHR. These observations underscore the importance of targeting this pathway in new antiallergic asthma drug development.

Anti-interleukin 5 but not anti-IgE prevents airway inflammation and airway hyperresponsiveness.

The role of IL-5 and allergen-specific IgE in the development of eosinophilic airway inflammation and airway hyperresponsiveness (AHR) was investigated in a murine model. BALB/c mice were sensitized to ovalbumin (OVA) by intraperitoneal injection on Days 1 and 14, followed by airway challenge with OVA on Days 28 and 29. Anti-IL-5 (TRFK-5) or anti-IgE (antibody 1-5) was administered before each airway challenge. Sensitized and challenged mice developed increased OVA-specific IgE serum levels, Th2 cytokine production by peribronchial lymph node (PBLN) cells, increased numbers of eosinophils (predominantly located in the peribronchial regions of the lungs), and increased airway responsiveness to methacholine (MCh). Anti-IgE treatment significantly decreased serum anti-OVA IgE levels and prevented the development of anaphylaxis but failed to affect T cell function, eosinophil airway infiltration, and AHR in sensitized and challenged mice. In contrast, treatment with anti-IL-5 antibody did not affect B cell (Ig serum levels), T cell (cytokine production), or mast cell function (immediate cutaneous reactivity) but completely inhibited development of eosinophilic lung inflammation and AHR. These data identify IL-5-mediated eosinophilia as a major target for development of AHR in this model, with little effect resulting from neutralization of IgE.

The late, but not early, asthmatic response is dependent on IL-5 and correlates with eosinophil infiltration.

Early-phase reactions (EPRs) and late-phase reactions (LPRs) are characteristic features of bronchial asthma, although the pathogenetic mechanisms responsible for each of the responses are not fully defined. A murine model of EPRs and LPRs was developed to investigate the role of IL-5 and eosinophils in development of both responses. After initial intraperitoneal sensitization and airway challenge to ovalbumin (OVA), mice were provoked by additional exposure to OVA. An EPR, characterized by a transient increase in airway responsiveness, was observed 5-30 minutes after antigen provocation. This response was followed by an LPR that reached its maximum at 6 hours after challenge and was characterized by increased airway responsiveness and significant lung eosinophilia. The EPR was blocked by cromoglycate and albuterol, whereas the LPR was abolished by cromoglycate and hydrocortisone. Before provocation with allergen, administration of anti-IL-5 antibody prevented the influx of eosinophils into the lung tissue and abolished the LPR but not EPR. These results suggest that IL-5 and eosinophils are essential for development of the LPR, but not EPR, in this model.

Anti-CD86 (B7.2) treatment abolishes allergic airway hyperresponsiveness in mice.

Allergic sensitization in asthma develops as a consequence of complex interactions between T cells and antigen-presenting cells. We have developed several in vivo models to study allergen-specific T cell and B cell function and their relevance to allergic airway hyperresponsiveness (AHR), focusing on the role of the costimulatory molecules CD80 and CD86. Treatment of mice with anti-CD86, but not anti-CD80, significantly inhibited increased serum levels of ovalbumin (OA)-specific IgE and IgG1, airway eosinophilia, and AHR both after 10 d of OA aerosol exposure (in the absence of adjuvant) and after intraperitoneal sensitization followed by repeated airway challenges. Inhibition of AHR was associated with decreased IL-4 and IL-5 levels in the BAL fluid of sensitized mice, suggesting impaired Th2 function in anti-CD86-treated animals. This effect was not seen when mice received treatment only before allergen challenge, indicating that anti-CD86 acts through inhibition of allergic sensitization and not simply by inhibiting the influx of inflammatory cells. These data suggest that the CD86 costimulatory ligand plays a major role in the development of allergic inflammation and AHR in allergen-challenged mice. Further, this study demonstrates that T-B cell interactions during allergic sensitization are amenable to therapeutic manipulation and that selective blockade of accessory signals can be an effective means for modulating distinct T cell functions.

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

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

IL-5 and eosinophils are essential for the development of airway hyperresponsiveness following acute respiratory syncytial virus infection.

Viral respiratory infections can cause bronchial hyperresponsiveness and exacerbate asthma. In mice, respiratory syncytial virus (RSV) infection, which induces an immune response dominated by IFN-gamma, results in airway hyperresponsiveness (AHR) and eosinophil influx into the airways, both of which are prevented by pretreatment with anti-IL-5 Ab. To delineate the role of IL-5, IL-4, and IFN-gamma in the development of RSV-induced AHR and lung eosinophilia, we tested the ability of mice deficient in each of these cytokines to develop these symptoms of RSV infection. Mice deficient in either IL-5, IL-4, or IFN-gamma were administered infectious RSV intranasally, and 6 days later, airway responsiveness to inhaled methacholine was assessed by barometric body plethysmography, and numbers of lung eosinophils and production of IFN-gamma, IL-4, and IL-5 by mononuclear cells from peribronchial lymph nodes were monitored. RSV infection resulted in airway eosinophilia and AHR in both IL-4- and IFN-gamma-deficient mice, but not in IL-5-deficient mice. Reconstitution of IL-5-deficient mice with IL-5 restored these responses and enhanced the responses in IL-4-deficient mice. Anti-VLA-4 (very late Ag-4) treatment prevented lung eosinophilia and AHR following RSV infection and IL-5 reconstitution. We conclude that in response to RSV, IL-5 is essential for the influx of eosinophils into the lung and that eosinophils in turn are critical for the development of AHR. IFN-gamma and IL-4 are not essential for these responses to RSV infection.

Inhaled corticosteroid improves bronchial reactivity and decreases symptoms in patients with mitral stenosis.

STUDY OBJECTIVE: To determine if treatment with inhaled budesonide forte can diminish increased bronchial hyperreactivity and improve symptoms in patients with mitral valve stenosis. DESIGN: The study was randomized, double blind, and placebo controlled. SETTING: Outpatient/university hospital. PATIENTS: Twelve subjects, 8 female and 4 male, who qualified for mitral valve replacement. All subjects presented with increased bronchial reactivity to histamine at the time of the study. INTERVENTIONS: Patients received placebo or budesonide forte twice a day (1,200 mg/d) for 6 weeks. During the study, patients were treated with the same doses of diuretics and other medications that could affect bronchial reactivity. MEASUREMENTS: Spirometry, provocative concentration of histamine causing a 20% fall in the FEV1 (PC20H), symptom scores. RESULTS: In the treated group, the initial PC20H was 0.82+/-0.72 mg/mL; in the placebo group 1.39+/-1.3 mg/mL. After 6 weeks of treatment, PC20H was significantly higher (3.07+/-2.28 mg/mL; p > 0.01) in the budesonide-treated group and remained unchanged in the placebo group (1.49+/-0.91). Symptom scores were significantly lower after administration of budesonide forte (mean change, 4.0+/-2.6). CONCLUSIONS: Six weeks of treatment with budesonide forte significantly decreased bronchial reactivity to histamine and improved symptoms in patients with mitral valve stenosis.

Antigen-specific immunoglobulin-A prevents increased airway responsiveness and lung eosinophilia after airway challenge in sensitized mice.

Aeroallergens such as Amb a I from short ragweed are important in the development of allergic airway disease. We tested the ability of a human monoclonal immunoglobulin-A (IgA) antibody specific for Amb a I (A-IgA) to modulate airway responsiveness and lung eosinophilia after airway challenge with nebulized Amb a I or ragweed extract in mice sensitized to Amb a I or ragweed extract, respectively. A-IgA or nonspecific IgA (C-IgA) were given intranasally up to 8 h before each challenge. Allergen challenge resulted in increases in airway responsiveness, in numbers of lung eosinophils, and in Amb a I-specific IgE levels. These were prevented by pretreatment with A-IgA but not with C-IgA. Decreases in IFN-gamma and increases in IL-4 and IL-5 production following challenge with Amb a I were also reduced by A-IgA treatment. In contrast, increases in total IgE and total IgG and in numbers of lung neutrophils after challenge were not significantly affected by A-IgA, which additionally induced increased levels of Amb a I-specific IgG2a antibodies. In mice sensitized and challenged with ovalbumin (OVA), A-IgA did not affect airway responsiveness, lung eosinophilia, cytokine production, or immunoglobulin levels. These data indicate that allergen-specific IgA can prevent airway hyperresponsiveness and reduce eosinophil influx into the lungs following allergen challenge via the airways in sensitized mice, and these effects are allergen-specific. Neutralization of allergen may contribute to the effects of IgA, but the induction of allergen-specific IgG2a in A-IgA-treated mice suggests an immunomodulatory action for A-IgA.

Local treatment with IL-12 is an effective inhibitor of airway hyperresponsiveness and lung eosinophilia after airway challenge in sensitized mice.

BACKGROUND: Systemic administration of IL-12 can prevent airway hyperresponsiveness (AHR) in mice after sensitization and repeated allergen challenge. However, systemic IL-12 has been associated with severe adverse effects. OBJECTIVE: We determined whether IL-12 administration to the airways in a dose sufficiently low so as not to result in systemic effects can modify allergic inflammation and AHR after allergen challenge. METHODS: Mice were sensitized to ovalbumin by intraperitoneal injection and challenged with ovalbumin aerosol on 3 consecutive days. During the period of challenge, IL-12 was administered intranasally following 2 regimens, designated high (1500 ng) or low (150 ng). We monitored airway responsiveness to inhaled methacholine by barometric body plethysmography, lung inflammatory cells, local cytokine production, and, to assess systemic effects of IL-12 treatment, spleen weights and numbers of eosinophils in the bone marrow. RESULTS: Allergen challenge resulted in increases in airway responsiveness and in numbers of lung eosinophils. These increases were prevented by both high- and low-dose IL-12. Additionally, IL-12 administration resulted in enhanced local interferon-gamma production and prevented the increases in local IL-4 and IL-5 production after airway challenge. A high dose, but not a low dose, of IL-12 resulted in increased spleen weights and prevented the increase in numbers of bone marrow eosinophils after allergen challenge. CONCLUSION: These data indicate that local administration of IL-12 can prevent AHR and reduce lung eosinophilia after allergen challenge in sensitized mice without eliciting systemic adverse effects. IL-12 exerts these effects by inducing local T(H1)-type responses in the airways in a setting that is normally dominated by T(H2)-type responses.

[The influence of multiple histamine inhalation on nonspecific airway hyperresponsiveness to histamine in patients with bronchial asthma]. / Wplyw wielokrotnego wziewania histaminy na nieswoista nadreaktywnosc oskrzeli na histamine u chorych na astme oskrzelowa.

The study was performed in 19 patients with stable mild/moderate asthma aged from 16 to 66. Nonspecific airway hyperresponsiveness (AH) to histamine was measured according to Cockcroft's et al. method and expresses as PC20H in mg/ml. The study was controlled by inhalation of PBS. The histamine or PBS challenges were performed three times at 45 min. intervals on the third day in case when the stability of AH on two preceding days was observed. The geometric means of PC20H (xg PC20H) during the consecutive three days did not change. They were 0.97, 0.92, 0.87 mg/ml (p > 0.05) respectively. Three times histamine challenges performed on the same day induced the decrease of AH (xg PC20H increased from 1.48 to 6.55 mg/ml) in 5 patients. In 4 other subjects the increase of AH was observed (xg PC20H decreased from 1.14 to 0.20 mg/ml). In 10 subjects the three times histamine challenges performed on the same day had no influence on AH to histamine.