Novel immunopharmacological strategies for allergic asthma.
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Animals↗
Biomedical subjects
A J Van Oosterhout
Publications and source records attributed to A J Van Oosterhout.
Antigen-stimulated lung CD4+ cells produce IL-5, while lymph node CD4+ cells produce Th2 cytokines concomitant with airway eosinophilia and hyperresponsiveness.
OBJECTIVE AND DESIGN: We investigated whether airway inflammation in a mouse model of allergic asthma is related to antigen-specific T cell responses in the effector organ, the lung, and in the lung draining lymph nodes (LN). MATERIALS AND SUBJECTS: In BALB/c mice pathophysiological parameters were measured in vivo, and lung draining LN and lung cells were restimulated in vitro. TREATMENT: Mice were sensitized with ovalbumin and repeatedly challenged with ovalbumin or saline inhalation. METHODS: Airway reactivity, inflammation in the airways, serum levels of IgE were measured, and cytokine levels and proliferative responses were determined in antigen-stimulated lymphocyte cultures. RESULTS AND CONCLUSIONS: Sensitization results in antigen-specific Th0-like LN cells, despite the presence of antigen-specific IgE. Repeated antigen inhalation induced airway hyperresponsiveness and eosinophil infiltration concomitant with a shift towards Th2 cytokine production exclusively by lung draining LN T cells. Furthermore, these airway symptoms are associated with antigen-specific CD4+ effector T cells in the airway tissue producing only IL-5, but not IL-4, which are unable to proliferate.
Animals↗
Opposite effects of immunotherapy with ovalbumin and the immunodominant T-cell epitope on airway eosinophilia and hyperresponsiveness in a murine model of allergic asthma.
In the present study, we investigated immunotherapy using an entire protein or an immunodominant epitope in a murine model of allergic asthma. Immunotherapy was performed in ovalbumin (OVA)-sensitized mice before OVA challenge. Mice were treated subcutaneously with OVA, the immunodominant epitope OVA323-339, or vehicle. In vehicle-treated animals, repeated OVA challenge induced increased serum levels of OVA-specific immunoglobulin (Ig)G1, IgE, airway eosinophilia, and hyperresponsiveness, compared with saline-challenged animals. In addition, interleukin (IL)-4 and IL-5 production upon OVA restimulation of lung-draining lymph node cells in vitro were significantly increased in OVA-challenged animals. Immunotherapy using OVA significantly reduced airway eosinophilia and hyperresponsiveness. This finding was accompanied by significantly reduced OVA-specific IL-4 and IL-5 production. Further, OVA immunotherapy induced increased serum levels of OVA-specific IgG1, whereas OVA-specific IgG2a and IgE levels were not affected. In contrast to OVA immunotherapy, immunotherapy with OVA323-339 aggravated airway eosinophilia and hyperresponsiveness. OVA-specific IgG1, IgG2a, and IgE serum levels, and in vitro IL-4 and IL-5 production, were not affected. Thus, immunotherapy with protein resulted in beneficial effects on airway eosinophilia and hyperresponsiveness, which coincided with a local reduced T-helper 2 (Th2) response. In contrast, peptide immunotherapy aggravated airway hyperresponsiveness and eosinophilia, indicating a local enhanced Th2 response.
Animals↗
Prevention of Th2-like cell responses by coadministration of IL-12 and IL-18 is associated with inhibition of antigen-induced airway hyperresponsiveness, eosinophilia, and serum IgE levels.
Allergic asthma is thought to be regulated by Th2 cells, and inhibiting this response is a promising mode of intervention. Many studies have focused on differentiation of Th cells to the Th1 or Th2 subset in vitro. IL-4 is essential for Th2 development, while IL-12 induces Th1 development, which can be enhanced by IL-18. In the present study, we investigated whether IL-12 and IL-18 were able to interfere in Th2 development and the associated airway symptoms in a mouse model of allergic asthma. Mice were sensitized with OVA using a protocol that induces IgE production. Repeated challenges by OVA inhalation induced elevated serum levels of IgE, airway hyperresponsiveness, and a predominantly eosinophilic infiltrate in the bronchoalveolar lavage concomitant with the appearance of Ag-specific Th2-like cells in lung tissue and lung-draining lymph nodes. Whereas treatments with neither IL-12 nor IL-18 during the challenge period were effective, combined treatment of IL-12 and IL-18 inhibited Ag-specific Th2-like cell development. This inhibition was associated with an absence of IgE up-regulation, airway hyperresponsiveness, and cellular infiltration in the lavage. These data show that, in vivo, the synergistic action of IL-12 and IL-18 is necessary to prevent Th2-like cell differentiation, and consequently inhibits the development of airway symptoms in a mouse model of allergic asthma.
Animals↗
Involvement of IL-16 in the induction of airway hyper-responsiveness and up-regulation of IgE in a murine model of allergic asthma.
Experiments were designed to investigate the role of IL-16 in a mouse model of allergic asthma. OVA-sensitized mice were repeatedly exposed to OVA or saline aerosols. Bronchoalveolar lavage fluid (BALF) was collected after the last aerosol, and the presence of IL-16 was evaluated using a migration assay with human lymphocytes. Migration of lymphocytes was significantly increased in the presence of cell-free BALF from OVA-challenged mice compared with BALF from saline-challenged controls. This response was significantly inhibited after addition of antibodies to IL-16, demonstrating the presence of IL-16 in BALF of OVA-challenged animals. Immunohistochemistry was performed and revealed IL-16 immunoreactivity particularly in airway epithelial cells but also in cellular infiltrates in OVA-challenged mice. IL-16 immunoreactivity was absent in nonsensitized animals; however, some reactivity was detected in epithelial cells of sensitized but saline-challenged mice, suggesting that sensitization induced IL-16 expression in airway epithelium. Treatment of mice with antibodies to IL-16 during the challenge period significantly suppressed up-regulation of OVA-specific IgE in OVA-challenged animals. Furthermore, antibodies to IL-16 significantly inhibited the development of airway hyper-responsiveness after repeated OVA inhalations, whereas the number of eosinophils in bronchoalveolar lavage or airway tissue was not affected. In conclusion, IL-16 immunoreactivity is present in the airways after sensitization. After repeated OVA inhalation, IL-16 immunoreactivity is markedly increased and IL-16 is detectable in BALF. Furthermore, IL-16 plays an important role in airway hyper-responsiveness and up-regulation of IgE but is not important for eosinophil accumulation in a mouse model of allergic asthma.
Animals↗
Modulation of airway hyperresponsiveness and eosinophilia by selective histamine and 5-HT receptor antagonists in a mouse model of allergic asthma.
1. Since both histamine and 5-hydroxytryptamine (5-HT) can be released by murine mast cells, we investigated the possible role of these autacoids on airway hyperresponsiveness (AHR), eosinophil infiltration and serum-IgE levels in a murine model of allergic asthma. 2. Ovalbumin-sensitized mice were exposed to either ovalbumin (2 mg ml(-1)) or saline aerosols on 8 consecutive days. Starting one day before the challenge, animals were injected i.p. twice a day with a 5-HT-type 1 (5-HT1) or type 2 (5-HT2) receptor antagonist (methiotepine, 1.25 or 2.0 mg kg(-1) and ketanserin, 12 mg kg(-1), respectively) or a histamine-type 1 (H1) or type 2 (H2) receptor antagonist (mepyramine, 12 or 20 mg kg(-1) and cimetidine, 10 or 25 mg kg(-1), respectively). Furthermore, animals were injected with a combination of cimetidine and ketanserin or with an alpha-adrenoceptor antagonist (phentolamine, 5 mg kg(-1)). 3. In vehicle-treated ovalbumin-challenged animals airway responsiveness to intravenous injections of methacholine in vivo was significantly (9 fold increase, P<0.01) increased when compared to vehicle-treated saline-challenged animals. Furthermore, ovalbumin challenge of vehicle-treated animals induced a significant increase in both eosinophil numbers in bronchoalveolar lavage (BAL) fluid (0+/-0, vehicle/saline and 15.0+/-5.9 x 10(4) cells vehicle/ovalbumin, P<0.05) and ovalbumin-specific IgE levels in serum (157+/-69 and 617+/-171 units ml(-1), respectively, P<0.05) compared to saline-challenged mice. Virtually no eosinophils could be detected in saline-challenged animals after all different treatments. 4. Treatment with ketanserin or cimetidine resulted in a partial but significant decrease of the ovalbumin-induced AHR compared to ovalbumin-challenged controls (P<0.05) and reduced eosinophil infiltration after ovalbumin challenge by 60% and 58%, respectively. The combination of cimetidine and ketanserin almost completely abolished AHR whereas eosinophilia was decreased by 49%. No effects of these antagonists were observed on IL-16 levels in BAL fluid or on serum antigen-specific IgE levels. Treatment with either the H1-receptor, the 5-HT1-receptor or the alpha-adrenoceptor antagonist, did not decrease the observed ovalbumin-induced airway responsiveness or eosinophilia in vehicle-treated animals. Higher doses of either methiotepine (2.0 mg kg(-1)) or mepyramine (20 mg kg(-1)) did decrease ovalbumin-induced eosinophil infiltration (by 67%, P<0.05 and 73%, respectively), whereas no effects of these antagonists were observed on ovalbumin-specific IgE levels in serum. 5. From these data it can be concluded that both histamine and 5-HT play a role in antigen-induced AHR and eosinophilia in the mouse.
Airway Resistance↗
Vbeta8+ T lymphocytes are essential in the regulation of airway hyperresponsiveness and bronchoalveolar eosinophilia but not in allergen-specific IgE in a murine model of allergic asthma.
BACKGROUND: There is increasing evidence that in allergic asthma the inflammatory process is regulated by T lymphocytes. In BALB/c mice the majority of ovalbumin responsive T lymphocytes express the Vbeta8.1+ and Vbeta8.2+ T-cell receptor. OBJECTIVE: We analysed the contribution of Vbeta8+ T lymphocytes during the sensitization and challenge phase in the regulation of antigen-specific IgE, airway hyperresponsiveness and cellular infiltration in the airways in a murine model of allergic asthma. METHODS: Mice strains genetically lacking (SJL/J and SJA/9) and expressing (BALB/c) the Vbeta8+ T cell receptor were used. In addition, prior to the sensitization and prior to the challenge BALB/c mice were treated with antibodies to Vbeta8. Mice were sensitized with ovalbumin, followed by repeated challenge with ovalbumin or saline aerosols. RESULTS: In ovalbumin challenged BALB/c mice treated with control antibody a significant increase in eosinophils in the bronchoalveolar lavage, airway hyperresponsiveness and increased serum levels of ovalbumin-specific IgE were observed compared to control mice. Treatment of BALB/c mice with antibodies to Vbeta8 prior to the sensitization or prior to the challenge period completely inhibited the ovalbumin induced infiltration of eosinophils and airway hyperresponsiveness, while ovalbumin-specific IgE was slightly decreased. In SJA/9 and SJL/J mice ovalbumin challenge did not induce eosinophilic infiltration and airway hyperresponsiveness. In SJL/J mice ovalbumin challenge induced an upregulation of ovalbumin-specific IgE, however, in SJA/9 mice no upregulation was observed. CONCLUSION: It is demonstrated that Vbeta8+ T lymphocytes are essential for infiltration of eosinophils in the airways and development of airway hyperresponsiveness in a murine model of allergic asthma. In contrast, although Vbeta8+ T lymphocytes seem to be important for the extent of IgE levels, no essential role for Vbeta8+ T lymphocytes in the induction of antigen-specific IgE was observed.
Animals↗
Airway epithelial Fas ligand expression: potential role in modulating bronchial inflammation.
Epithelium-derived Fas ligand is believed to modulate inflammation within various tissues. In this paper, we report findings that suggest a similar immunoregulatory role for Fas ligand in the lung. First, Fas ligand was localized to nonciliated, cuboidal airway epithelial cells (Clara cells) throughout the airways in the normal murine lung by employing nonisotopic in situ hybridization and immunohistochemistry. Second, gld mutant mice, which express a dysfunctional Fas ligand protein, were noted to develop prominent infiltration of inflammatory cells in submucosal and peribronchial regions of the upper and lower airways. Third, during allergic airway inflammation induced by ovalbumin in mice, cell-associated staining for Fas ligand mRNA and protein was markedly reduced in the airway epithelium. These data suggest that Clara cell-derived Fas ligand may control immune activity in the airway; thus alterations in this protective mechanism may be involved in the pathogenesis of certain inflammatory conditions of the airway, such as asthma.
Animals↗
Allergen immunotherapy inhibits airway eosinophilia and hyperresponsiveness associated with decreased IL-4 production by lymphocytes in a murine model of allergic asthma.
In the present study, we investigated whether allergen immunotherapy is effective in a murine model with immunologic and pathophysiologic features reminiscent of allergic asthma. Ovalbumin-sensitized mice received increasing (1 microgram to 1 mg) subcutaneous doses of ovalbumin twice a week for 8 wk according to a semirush immunotherapy protocol as used in allergic patients. During immunotherapy, an initial rise in serum levels of ovalbumin-specific antibodies (immunoglobulin [Ig]G1, IgE, IgG2a) occurred, after which IgE levels decreased sharply concomitant with an increase in IgG2a levels. The increase in IgG2a levels, with the decline in IgE levels, suggests that during immunotherapy interferon-gamma production is increased or interleukin (IL)-4 production is decreased. After immunotherapy, inhalation challenge of the mice with ovalbumin revealed almost complete inhibition (98%, P < 0.01) of eosinophil infiltration into bronchoalveolar lavage and airway hyperresponsiveness (100% at 320 microgram/kg methacholine, P < 0.05) compared with sham-treated animals. In addition, IL-4 production of thoracic lymph node cells stimulated with ovalbumin in vitro was largely reduced (60%, P < 0.05) after immunotherapy. Thus, effective immunotherapy in this animal model appears to be due to modulation of antigen-specific T cells. Similar effects on airway symptoms and IL-4 production can be obtained within 1 wk by three injections of the highest dose of ovalbumin (1 mg). This animal model will be used as a preclinical model to improve allergen immunotherapy and to gain more insight into the mechanisms involved.
Alveolitis, Extrinsic Allergic↗
Differential effects of endogenous and exogenous interferon-gamma on immunoglobulin E, cellular infiltration, and airway responsiveness in a murine model of allergic asthma.
The inflammatory response as seen in human allergic asthma is thought to be regulated by Th2 cells. It has been shown that interferon-gamma (IFN-gamma) can downregulate the proliferation of Th2 cells and therefore might be of therapeutic use. In the present study we have investigated the in vivo role of endogenous and exogenous IFN-gamma in a murine model with features reminiscent of human allergic asthma. IFN-gamma gene knockout (GKO) and wild-type mice were sensitized with ovalbumin and exposed to repeated ovalbumin aerosol challenges. In addition, wild-type mice were treated with intraperitoneal or nebulized recombinant murine IFN-gamma during the challenge period. Sensitized wild-type mice exhibited upregulated ovalbumin-specific IgE in serum, and airway hyperresponsiveness and infiltration of eosinophils and mononuclear cells in the bronchoalveolar lavage fluid (BALF) after ovalbumin challenge. In contrast, in GKO mice only reduced eosinophilic infiltration in the BALF was observed after ovalbumin challenge. In wild-type mice, parenteral IFN-gamma treatment downregulated ovalbumin-specific IgE levels in serum, and airway hyperresponsiveness and cellular infiltration in the BALF, whereas aerosolized IFN-gamma treatment only suppressed airway hyperresponsiveness. In vitro experiments showed that these effects of IFN-gamma appear not to be mediated via a direct effect on the cytokine production of antigen-specific Th2 cells. These data indicate that airway hyperresponsiveness can be downregulated by IFN-gamma locally in the airways, whereas for downregulation of IgE and cellular infiltration systemic IFN-gamma is needed. The present study shows that exogenous IFN-gamma can downregulate the allergic response via an antigen-specific T-cell independent mechanism, but at the same time endogenous IFN-gamma plays a role in an optimal response.
Administration, Inhalation↗
Antibody to very late activation antigen 4 prevents interleukin-5-induced airway hyperresponsiveness and eosinophil infiltration in the airways of guinea pigs.
This study examines the effect of monoclonal antibody to very late activation antigen-4 (VLA-4) on IL5-induced airway hyperresponsiveness in vivo and eosinophil accumulation into guinea pig airways. IL5 has been shown to be important in the development of airway hyperresponsiveness and eosinophil accumulation in the guinea pig. Eosinophils, unlike neutrophils, express VLA-4 which mediates the adhesion to vascular cell adhesion molecule-1 on endothelial cells. Thus VLA-4 seems to be an important adhesion molecule in the infiltration of eosinophils from the vasculature into the airway tissue. In addition, it has been shown that IL5 activates VLA-4 on eosinophils to facilitate their adhesion. In the present study, IL5 (1 microg, twice on one day) or vehicle were administered intranasally. Monoclonal antibody (mAb) to VLA-4 (HP1/2) or the isotype-matched control mAb (1E6) were injected 1 hour before each IL5 or vehicle treatment at a dose of 2.5 mg/kg body weight. The next day in vivo bronchial reactivity, eosinophil number in bronchoalveolar lavage (BAL) fluid, and eosinophil peroxidase (EPO) activity in cell-free BAL fluid were determined. IL5 induces an increase in bronchial reactivity to histamine, which is associated with an accumulation of eosinophils into BAL fluid (control: 12 (5 to 42) x 10(5) cells and IL5: 69 (11 to 99) x 10(5) cells, p < 0.05) and an increase of 35% +/- 14% in EPO activity in cell-free BAL fluid. Intravenous administration of anti-VLA-4 mAb, but not of the control antibody, completely inhibits the bronchial hyperresponsiveness as well as the airway eosinophilia found after intraairway application of IL5. HP1/2 also suppresses the IL5-induced increase in EPO activity in cell-free BAL fluid. In conclusion, for the development of IL5-induced airway hyperresponsiveness in the guinea pig, the VLA-4-dependent infiltration and activation of eosinophils in the bronchial tissue seems to be essential.
Animals↗
Role for neurokinin-2 receptor in interleukin-5-induced airway hyperresponsiveness but not eosinophilia in guinea pigs.
In the guinea pig, interleukin-5 (IL-5) has been shown to induce airway hyperresponsiveness as well as eosinophilia, which are important symptoms in asthma. IL-5 seems to be a critical cytokine since it selectively affects eosinophil functions. The mechanism of action by which IL-5 leads to airway hyperresponsiveness may be important for our understanding of the pathogenesis of asthma. Neurogenic inflammation, which is mediated by nonadrenergic noncholinergic nerves (NANC), may play a role in the IL-5-induced effects in guinea pig airways. In this study, the role of neuropeptides in the IL-5-induced airway hyperresponsiveness and eosinophilia in the guinea pig was examined using selective neurokinin receptor antagonists. Intra-airway application of IL-5 (1 microgram, twice) induces a selective eosinophil migration (control: 12 [8-22] x 10(5) cells and IL-5: 90 [67-187] x 10(5) cells, p < 0.05) and activation (control: 6.3 +/- 0.9 ng eosinophil peroxidase [EPO]/ml bronchoalveolar lavage [BAL] fluid and IL-5: 29.3 +/- 4.9 ng EPO/ml BAL fluid, p < 0.05) and a pronounced airway hyperresponsiveness in vivo. The maximal responses to histamine are increased by 160 +/- 16% (p < 0.05) after IL-5. Treatment of guinea pigs with either the nonselective neurokinin (NK)-receptor antagonist, FK224, or the selective NK2-receptor antagonist, SR48968, results in a complete inhibition of the in vivo hyperresponsiveness found after application of IL-5. Vice versa, intra-airway administration of substance P (10 micrograms, twice) results in an airway hyperresponsiveness (increased maximal response after substance P: 166 +/- 15% [p < 0.05]) without inducing migration or activation of eosinophils. All examined NK-receptor antagonists do not influence the IL-5-induced eosinophil accumulation. In addition, no effect of the NK-receptor antagonists is observed on the IL-5-induced eosinophil activation, as determined by BAL fluid EPO levels. The release of NK2-receptor active tachykinins plays an important role in the development of IL-5-induced airway hyperresponsiveness. This feature appears to be a step following eosinophil infiltration and activation since there are no effects on eosinophil function by pretreatment of the used NK-receptor antagonists.
Airway Resistance↗
Development of airway hyperresponsiveness is dependent on interferon-gamma and independent of eosinophil infiltration.
In this study the role of interleukin (IL)4, IL5, interferon (IFN) gamma, and tumor necrosis factor (TNF) alpha in the development of airway hyperresponsiveness and inflammatory cell infiltration was investigated using a murine model for allergic asthma. Mice were sensitized with ovalbumin and subsequently challenged repeatedly with ovalbumin aerosols. During the challenge period, mice were treated with monoclonal antibodies directed against IL4, IL5, IFN gamma, or TNF alpha. Control antibody-treated mice showed airway hyperresponsiveness to methacholine and the presence of eosinophils in bronchoalveolar lavage (BAL). Treatment with antibodies to IFN gamma completely abolished development of airway hyperresponsiveness in ovalbumin-challenged animals. After treatment with antibodies to TNF alpha, airway hyperresponsiveness in the ovalbumin-challenged animals was partially but not significantly inhibited. Antibodies to IL4 or IL5 did not inhibit airway hyperresponsiveness. The presence of eosinophils in BAL of ovalbumin-challenged mice was completely inhibited after treatment with antibodies to IL5. Treatment with antibodies to IL4, IFN gamma, or TNF alpha had no effect on eosinophilia. Because IFN gamma and IL5 have either an effect on the induction of airway hyperresponsiveness or on the development of eosinophil infiltration, our results suggest that the two phenomena are differentially regulated.
Administration, Inhalation↗
Murine CTLA4-IgG treatment inhibits airway eosinophilia and hyperresponsiveness and attenuates IgE upregulation in a murine model of allergic asthma.
Antigen-specific T-cell activation requires the engagement of the T-cell receptor (TCR) with antigen as well as the engagement of appropriate costimulatory molecules. One of the most important pathways of costimulation is the interaction of CD28 on the T cell with B7-1/B7-2 on antigen-presenting cells. In the present study, we have examined the in vivo effects of blocking the CD28:B7 T-cell costimulatory pathway by administration of mCTLA4-IgG in a murine model of allergic asthma. Mice were sensitized with ovalbumin and exposed to repeated ovalbumin inhalation challenges. In mice treated with a control antibody at the time of ovalbumin challenge a significant increase in the number of eosinophils (12.8 +/- 4.3 x 10(3) cells, P < 0.05) in the bronchoalveolar lavage (BAL) fluid and airway hyperresponsiveness to methacholine (49 +/- 15%, P < 0.05) was observed. In addition, serum levels of ovalbumin-specific IgE were significantly (P < 0.01) increased after ovalbumin challenge compared with saline challenge (1,133 +/- 261 experimental units [EU]/ml and 220 +/- 63 EU/ml, respectively). In mice treated with mCTLA4-IgG at the time of ovalbumin challenge, the infiltration of eosinophils into BAL fluid and the development of airway hyperresponsiveness to methacholine were completely inhibited. The upregulation of ovalbumin-specific IgE levels in serum was attenuated by mCTLA4-IgG treatment. Furthermore, addition of mCTLA4-IgG to cultures of parabronchial lymph node cells from sensitized mice inhibited the ovalbumin-induced interleukin-4 production. These data indicate the therapeutic potential of blocking T-lymphocyte costimulation by CTLA4-IgG as a possible immunosuppressive treatment for patients with allergic asthma.
Abatacept↗
Salmeterol inhibits interferon-gamma and interleukin-4 production by human peripheral blood mononuclear cells.
T-lymphocytes play an important role in allergic asthma. In the present study, the effect of beta(2)-adrenoceptor agonists was examined on proliferation, interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) production by human peripheral blood mononuclear cells (PBMC). The proliferation after 24 h phytohaemagglutinin (PHA) activation was significantly inhibited at high concentrations of salmeterol, isoprenaline and salbutamol (> or = 10(-6) M). A U-shaped concentration response curve was observed for the effect of all agonists on IL-4 production 24 h after PHA activation. Maximal inhibition occurred at 10(-9) M and amounted to 71% (P < 0.02), 38% (P < 0.01) and 49% (P < 0.01) for salmeterol, isoprenaline and salbutamol, respectively. In contrast, no significant effect of salmeterol (10(-11)-10(-5) M) on IL-4 production could be detected after 96 h. A biphasic concentration response curve was observed for the inhibitory activity of all beta-adrenoceptor agonists on IFN-gamma production by PBMC 24 h after PHA activation. The first phase reached a plateau at 10(-9) M and the inhibition amounted to 50% (P < 0.05), 33% (P < 0.01) and 44% (P < 0.05) for salmeterol, isoprenaline and salbutamol, respectively. At higher concentrations of the three beta-adrenoceptor agonists the inhibition was increased up to 80% (P < 0.05), 60% (P < 0.05) and 58% (P < 0.01), respectively. Similar to the results obtained after 24 h, IFN-gamma production after 96 h was biphasically inhibited by salmeterol, and this inhibition (60%) was significantly at 10(-5) M. Together, the present data provide clear evidence for concentration-dependent effects of beta-adrenoceptor agonists on the IL-4 and IFN-gamma production by human PBMC. These results suggest that beta-agonists, at low concentrations, predominantly inhibit IL-4 production and may therefore act as anti-inflammatory drugs in allergic asthma.
Adrenergic beta-Agonists↗
Effect of dexamethasone and endogenous corticosterone on airway hyperresponsiveness and eosinophilia in the mouse.
1. Mice were sensitized by 7 intraperitoneal injections of ovalbumin without adjuvant (10 micrograms in 0.5 ml of sterile saline) on alternate days and after 3 weeks exposed to either ovalbumin (2 mg ml-1 in sterile saline) or saline aerosol for 5 min on 8 consecutive days. One day before the first challenge, animals were injected intraperitoneally on a daily basis with vehicle (0.25 ml sterile saline), dexamethasone (0.5 mg kg-1) or metyrapone (30 mg kg-1). 2. In vehicle-treated ovalbumin-sensitized animals ovalbumin challenge induced a significant increase of airway responsiveness to metacholine both in vitro (27%, P < 0.05) and in vivo (40%, P < 0.05) compared to saline-challenged mice. Virtually no eosinophils could be detected after saline challenge, whereas the numbers of eosinophils were significantly increased (P < 0.01) at both 3 and 24 h after the last ovalbumin challenge (5.48 +/- 3.8 x 10(3) and 9.13 +/- 1.7 x 10(3) cells, respectively). Furthermore, a significant increase in ovalbumin-specific immunoglobulin E level (583 +/- 103 units ml-1, P < 0.05) was observed after ovalbumin challenge compared to saline challenge (201 +/- 38 units ml-1). 3. Plasma corticosterone level was significantly reduced (-92%, P < 0.001) after treatment with metyrapone. Treatment with metyrapone significantly increased eosinophil infiltration (17.4 +/- 9.93 x 10(3) and 18.7 +/- 2.57 x 10(3) cells, P < 0.05 at 3 h and 24 h, respectively) and potentiated airway hyperresponsiveness to methacholine compared to vehicle-treated ovalbumin-challenged animals. Dexamethasone inhibited both in vitro and in vivo hyperresponsiveness as well as antigen-induced infiltration of eosinophils (0, P < 0.05 and 0.7 +/- 0.33 x 10(3) cells, P < 0.05 at 3 h and 24 h, respectively). Metyrapone as well as dexamethasone did not affect the increase in ovalbumin-specific immunoglobulin E levels after ovalbumin challenge (565 +/- 70 units/ml-1; P < 0.05; 552 +/- 48 units ml-1, P < 0.05 respectively). 4. From these data it can be concluded that exogenously applied corticosteroids can inhibit eosinophil infiltration as well as airway hyperresponsiveness. Vise versa, endogenously produced corticosteroids play a down-regulating role on the induction of both eosinophil infiltration and airway hyperresponsiveness.
Animals↗
Role of interleukin-5 and substance P in development of airway hyperreactivity to histamine in guinea-pigs.
In this study, we examined the mechanism by which bronchoalveolar lavage (BAL) cells induced hyperreactivity of the trachea in vitro. As both interleukin-5 (IL-5) and substance P (SP) appeared to be involved, the effect of these mediators was examined in vivo. Tracheae were incubated with BAL cells from ovalbumin or saline challenged animals, and from naive animals, in the absence or presence of either IL-5, SP, or both. In addition, the effect of intra-airway application of IL-5, SP, both, or vehicle on tracheal hyperreactivity was examined. Incubation of tracheae with BAL cells from ovalbumin challenged animals induced an increase (30 +/- 10%) in the maximal response to histamine. The hyperreactivity could be completely inhibited by co-incubation with 5-lipoxygenase inhibitor, AA861. The hyperreactivity could be mimicked by incubation of tracheae with BAL cells from naive animals in the presence of IL-5 and SP. After in vivo administration of either IL-5 or SP, maximal responses to histamine were increased and amounted to 105 +/- 35 and 101 +/- 37%, respectively. Administration of IL-5 but not SP induced a significant increase in the number of eosinophils (67 +/- 22%) and eosinophil peroxidase (EPO) activity (94 +/- 33%) in BAL cells. The simultaneous administration of IL-5 and SP did not potentiate the hyperreactivity and eosinophilia observed with IL-5 alone. These data suggest that IL-5 is important in the recruitment of eosinophils, whereas both IL-5 and substance P are involved in the induction of airway hyperreactivity.
Animals↗
Bronchoconstriction and airway hyperresponsiveness after ovalbumin inhalation in sensitized mice.
To investigate the mechanisms underlying airway hyperresponsiveness a murine model was developed with several important characteristics of human allergic asthma. Mice were intraperitoneally sensitized with ovalbumin and after 4 weeks challenge via an ovalbumin aerosol. After aerosol, lung function was evaluated with a non-invasive forced oscillation technique. The amount of mucosal exudation into the airway lumen and the presence of mast cell degranulation was determined. Tracheal responsiveness was measured at several time points after challenge. At these time points also bronchoalveolar lavage and histology were performed. Sensitization induced high antigen-specific IgE levels in serum. Inhalation of ovalbumin in sensitized mice induced an immediate but no late bronchoconstrictive response. During this immediate phase, respiratory resistance was increased (54%). Within the first hour after ovalbumin inhalation increased mucosal exudation and mast cell degranulation were observed. At 12 and 24 h after ovalbumin challenge, mice showed tracheal hyperresponsiveness (29% and 34%, respectively). However, no apparent inflammation was found in the lungs or bronchoalveolar lavage. From these results it can be concluded that hyperresponsiveness can develop via mechanisms independent of an inflammatory infiltrate. Since mast cell degranulation occurred after ovalbumin exposure, we hypothesize that mast cells are involved in the induction of airway hyperresponsiveness in this model.
Animals↗