Search

The aim of this study was to investigate the possible role of capsaicin-sensitive nerves in a pulmonary delayed-type hypersensitivity (DTH) reaction. Mice (Balb/c) were skin-sensitized with dinitrofluorobenzene (DNFB; 0.5%, 100 microliters) on two consecutive days and challenged intranasally 5 days later with dinitrobenzene sulphonic acid (0.6%, 50 microliters). Sensitized mice exhibited tracheal hyperreactivity to carbachol 24 and 48 h after challenge; however, no hyperreactivity was observed 2 h after challenge. At 24 h, but not at 48 h, hyperreactivity was associated with antigen-specific lymphocyte accumulation in bronchoalveolar lavage fluid (BALF). Capsaicin pretreatment, resulting in the depletion of sensory neuropeptides, virtually abolished hyperreactivity to carbachol 24 and 48 h after challenge in sensitized mice. Although at 24 h after challenge the lymphocyte population was elevated in the BALF collected from capsaicin-pretreated mice, this accumulation was not antigen-specific. Additionally, there was an increase in polymorphonuclear leukocyte accumulation (neutrophils and eosinophils) in the BALF collected from capsaicin-pretreated mice at this time point, but this increase was more profound in the sensitized group. In summary, tracheal hyperreactivity and cellular accumulation are prominent features of the lymphocyte-associated DTH reaction induced by DNFB in the mouse lung. Evidence presented in this report highlights the possible importance of sensory neuropeptides in pulmonary inflammation and airways hyperreactivity.

Chronic obstructive pulmonary disease (COPD) is characterized by chronic airway inflammation. Cigarette smoke has been considered a major player in the pathogenesis of COPD. The inflamed airways of COPD patients contain several inflammatory cells. Vitamin A metabolites have been implicated in the repair of lung damage. Exposure to cigarette smoke has been shown to depress levels of retinol in lungs of rats. The purpose of this study was to investigate if a low, but not deficient, vitamin A status potentiated susceptibility to the development of cigarette smoke-induced lung emphysema in mice. Mice were bred that were the offspring's of 3 generations of mice that were fed a purified diet containing low levels of vitamin A and exposed to cigarette smoke for 3 months, every weekday. Then, levels of 9-cis, 13-cis, and all-trans retinoic acid, retinol and retinyl palmitate were measured in plasma, liver and right lung lobe. The left lung lobe was used to assess mean linear intercept (Lm), as a measure of smoke-induced lung damage. Average feed intakes were not different between treatment groups. We show that both retinol and retinyl palmitate levels were dramatically decreased in the storage organs of mice on the low vitamin A diet (retinol 2-fold in both lung and liver, and retinyl palmitate 5- fold in lung) which shows that the depletion was successful. However, this treatment did not result in the development of lung emphysema. However, smoke exposure led to a significant increase in Lm in mice with a low vitamin A status compared to the room air-breathing controls. Lung levels of acid retinoids were similar in all mice, irrespective of diet or smoke exposure. Concluding, a low vitamin A status increases the susceptibility to the development of cigarette smoke-induced lung emphysema, possibly because of decreased anti-oxidant capacity in the lungs due to locally reduced retinol and retinyl palmitate levels. These observations indicate that human populations with a low vitamin A status and a high prevalence of smoking may be at increased risk of developing lung emphysema.

The existence of a third B7-1/B7-2 receptor was postulated in a recent study using a novel mouse strain lacking both CD28 and CTLA4 (CD28/CTLA4-/-).In the present study, it was investigated if T cell co-stimulation via the putative B7-1/B7-2 receptor plays a role in the induction of Th2-mediated asthma manifestations in mice.BALB/c wild-type, CD28/CTLA4-/- and B7-1/B7-2-/- mice were sensitized and aerosol challenged with ovalbumin (OVA).At 24 h after the last aerosol, wild-type mice showed airway hyper-responsiveness in vivo and up-regulated levels of serum OVA-specific IgE compared with the situation shortly before OVA challenge. In addition, eosinophil numbers and IL-5 levels in the broncho-alveolar lavage fluid and Th2 cytokine production by lung cells upon OVA re-stimulation in vitro were observed. In agreement with an earlier study, we failed to induce any of the asthma manifestations in B7-1/B7-2-/- mice. Importantly, also CD28/CTLA4-/- mice showed no asthma manifestations upon OVA sensitization and challenge.These data clearly demonstrate that T cell co-stimulation via the putative B7-1/B7-2 receptor appears to have no role in the induction of Th2-mediated asthma manifestations in this murine model and, conversely, that CD28 signalling is crucial.

The hygiene hypothesis suggests that a lack of bacterial infections would favour the development of allergic disease. For this reason, bacteria or their components can be used as potential treatment for allergic asthma. We investigated whether heat-killed Mycobacterium vaccae is either able to suppress the induction of allergic asthma or able to suppress already established allergic asthma.Mice were sensitized with ovalbumin (OVA)/alum on days 0 and 14. Thereafter, mice were challenged on days 35, 39 and 42 by inhalation of either OVA or saline aerosols. M. vaccae-treated mice received an injection with 106, 107 or 108 CFU heat-killed M. vaccae on days 0 and 14 or 107 CFU on days 35 and 39. On day 43, the airway responsiveness of the mice to increasing concentrations of methacholine was assessed, blood was withdrawn to measure serum parameters, and lung lavage was performed to detect cytokines and inflammatory cell number.Treatment of OVA-sensitized mice with 107 CFU M. vaccae either during sensitization or challenge suppresses airway hyper-responsiveness, airway eosinophilia and IL-5 production after OVA challenge. The increases in OVA-specific serum IgE and in IL-4 by respiratory challenges with OVA were only diminished after M. vaccae treatment (107 CFU) during sensitization.Heat-killed M. vaccae prevents allergic and asthmatic manifestations in a mouse model and, more importantly, M. vaccae treatment during challenge suppresses features of asthma, which opens up possibilities for new therapeutic interventions.

IL-16 has been described as a natural soluble CD4-ligand with immunosuppressive effects in vitro. However, little is known about the effect of IL-16 on immune responses in vivo.In the present study, we examined the effect of IL-16 administration in a murine model of allergic asthma. Next, we determined whether these effects were mediated by modulation of CD4+ T lymphocytes.Intraperitoneal administration of IL-16 completely inhibits antigen-induced airway hyper-responsiveness and largely decreases the number of eosinophils in bronchoalveolar lavage fluid (90%) and airway tissue of ovalbumin-sensitized and challenged mice. Firstly, it appears that thoracic lymph node cells isolated from in vivo IL-16-treated ovalbumin-challenged animals produce less IL-4 (77%) and IL-5 (85%) upon antigenic re-stimulation, when compared to vehicle-treated mice. Secondly, pre-incubation of lymphocytes with IL-16 in vitro reduces antigen-induced proliferation (55%) and Th2-type cytokine production (IL-4; 56%, IL-5; 77%). Thirdly, the presence of IL-16 during priming cultures of TCR transgenic T cells (DO11.10), reduces IL-4 (33%) and IL-5 (35%), but not IL-10 and IFNgamma levels upon re-stimulation.It can be concluded that IL-16 has potent immunosuppressive effects on a Th2dominated allergic airway response.

Peptoid-peptide hybrids are oligomeric peptidomimetics that contain one or more N-substituted glycine residues. In these hybrids, the side chains of one or several amino acids are "shifted" from the alpha-carbon atom to the amide nitrogen atom. A library of phosphorylated peptoid-peptide hybrids derived from the sequence pTyr-Glu-Thr-Leu was synthesized and tested for binding to the tandem SH2 domain of the protein tyrosine kinase Syk. A considerable influence of the side chain position was observed. Compounds 19-21, 24, and 25 comprising a peptoid NpTyr and/or NGlu residue did not show any binding. Compounds 22, 23, and 26 containing an NhThr (hThr=homothreonine) and/or NLeu peptoid residue showed binding with IC(50) values that were only five to eight times higher than that of the tetrapeptide lead compound 18. These data show that side chain shifting is possible with retention of binding capacity, but only at the two C-terminal residues of the tetramer. This method of a peptoid scan using peptoid-peptide hybrids appears to be very useful to explore to what extent a peptide sequence can be transformed into a peptoid while retaining its affinity.

1. Nerve growth factor induces an airway hyperresponsiveness in vivo in guinea-pigs, as we have shown previously. Since antagonizing the neurokinin-1 (NK(1)) receptor can prevent this NGF-induced airway hyperresponsiveness and since sensory nerves release tachykinins, we investigated the role of sensory nerves in the NGF-induced airway hyperresponsiveness. 2. We used isolated tracheal rings from guinea-pigs to measure tracheal contractility. In these rings sensory nerve endings are present, but these endings lack any contact with their cell bodies. 3. In this in vitro system, NGF dose-dependently induced a tracheal hyperresponsiveness to histamine. The NK(1) receptor antagonist SR140333 could block the induction of tracheal hyperresponsiveness. 4. To further investigate the involvement of sensory nerve endings we used the cannabinoid receptor 1 (CB(1)) agonist R-methanandamide to inhibit excitatory events at the nerve terminal. The CB(1) receptor agonist was capable of blocking the tracheal hyperresponsiveness to NGF in the isolated system, as well as the airway hyperresponsiveness to NGF in vivo. 5. This indicates that NGF can induce an increase in airway responsiveness in the absence of sensory nerve cell bodies. NGF may act by increasing substance P release from sensory nerve endings, without upregulation of substance P in the neurons. Substance P in its turn is responsible for the induction of the NGF-induced airway hyperresponsiveness.

1. The contribution of reactive nitrogen species to the development of airway hyperresponsiveness in a mouse model of allergic inflammation was investigated by the use of selective inhibitors of nitric oxide and superoxide formation. 2. Sensitized mice, repeatedly challenged with ovalbumin showed a significant (P0.001, n=9) increase in airway responsiveness measured using whole body plethysmography. This hyperresponsiveness was accompanied by an influx of eosinophils into the airway lumen and increased levels of ovalbumin-specific serum IgE. 3. Treatment of mice with the iNOS inhibitor 1400 W or the NADPH-oxidase inhibitor apocynin did not significantly alter cellular influx into the airway lumen nor serum ovalbumin specific IgE. In contrast, apocynin as well as 1400 W inhibited ovalbumin-induced airway hyperresponsiveness (P0.001 and P0.05 respectively, n=9). Furthermore, the airways of allergen challenged animals showed clear 3-nitrotyrosine staining, which was mainly located in eosinophils. Remarkably, treatment with apocynin or 1400 W did not alter 3-nitrotyrosine staining. 4. These data suggest that the development of airway hyperresponsiveness during the airway inflammation upon ovalbumin challenge is dependent on the release of both superoxide and nitric oxide and is therefore likely to be dependent on reactive nitrogen species. This mechanism, however, is not reflected by 3-nitrotyrosine formation in the airways.

Peroxynitrite (ONOO(-)) the highly reactive coupling product of nitric oxide and superoxide, has been implicated in the pathogenesis of an increasing number of (inflammatory) diseases. At present, however, selective peroxynitrite antagonizing agents with therapeutic potential are not available. Therefore, the NADPH-oxidase inhibitor apocynin (4-hydroxy-3-methoxy-acetophenone) was tested for its ability to inhibit peroxynitrite formation in vitro The murine macrophage cell-line J774A.1, stimulated with IFNgamma/LPS, was used as a model. Conversion of 123-dihydrorhodamine (123-DHR) to its oxidation product 123-rhodamine was used to measure peroxynitrite production. Stimulated peroxynitrite formation could be completely inhibited by apocynin, by the superoxide scavenger TEMPO as well as by the nitric oxide synthase inhibitor aminoguanidine. Apocynin and aminoguanidine specifically inhibited superoxide and nitric oxide formation respectively as confirmed by measuring lucigenin enhanced chemiluminescence and nitrite accumulation. It is concluded that J774A.1 macrophages produce significant amounts of peroxynitrite, which is associated with nitric oxide production and NADPH-oxidase dependent superoxide formation. The NADPH-oxidase inhibitor apocynin proved to be a potent inhibitor of both superoxide and peroxynitrite formation by macrophages, which may be of future therapeutic significance in a wide range of inflammatory disorders.

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.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.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.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.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.

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.

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, P0.01) 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, P0.05) and ovalbumin-specific IgE levels in serum (157+/-69 and 617+/-171 units ml(-1), respectively, P0.05) 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 (P0.05) 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%, P0.05 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.

In this study, the role for sensory neuropeptides in the induction of pulmonary inflammation associated with a delayed-type hypersensitivity (DTH) reaction in the mouse lung was investigated. Dinitrofluorobenzene (DNFB) was used as the sensitizing hapten and dinitrobenzene sulfonic acid was used as the intranasal challenge. Two hours after the challenge, no hapten-specific differences were observed between vehicle- and DNFB-sensitized mice. However, mucosal exudation and leukocyte accumulation (mononuclear leukocytes and neutrophils) were enhanced in the DNFB group 24 h after the challenge. In additional experiments we investigated whether the sensory nerves and specific sensory neuropeptides play a role in this pulmonary DTH reaction. The selective NK1 antagonist (RP 67580; 5.10(-9) mol/mouse), administered 5 min before and 1 h after the challenge, suppressed mucosal exudation and leukocyte accumulation in the airways 24 h after the challenge. In contrast, the selective calcitonin gene-related peptide (CGRP) antagonist, CGRP8-37 (5.10(-9) mol/mouse) had no effect on the pulmonary DTH reaction. Surprisingly, the depletion of all sensory neuropeptides resulted in an enhancement of mucosal exudation in vehicle- and DNFB-sensitized mice 24 h after the challenge. In conclusion, these results demonstrate that the tachykinins are important in mediating mucosal exudation and leukocyte accumulation associated with the DTH reaction in mouse airways. However, the findings in neuropeptide-depleted mice suggest that the sensory nerves may also play a protective role in mouse airways.

Inadequate reactions of the immune system, i.e. allergic or hypersensitivity reactions, may lead to lung tissue injury and possibly airway hyperreactivity. In extrinsic asthma, mast cells are considered to play a pivotal role in inducing hyperreactivity by producing various mediators. Immunoglobulin E is a well-known inducer of mast cell mediator release, and is thus often considered important. Asthma induced by a small molecular moiety such as toluene diisocyanate (TDI) is only in 15% of patients associated with increased IgE levels. TDI is a known inducer of cellular immune responses. We are investigating the relationship of type IV hypersensitivity, as an example of IgE-independent cellular hypersensitivity, with the induction of airway hyperreactivity. We have studied mice which were sensitized with picryl chloride. After antigen challenge in such sensitized mice, peribronchial and perivascular accumulation of macrophages and lymphocytes was highest 48 h after challenge. Two hours after challenge and from 7 days onwards no infiltration was found. At several time points after challenge, changes in smooth muscle tone of mouse tracheas were measured isometrically. The response to carbachol increased from 2 h after challenge, reaching a maximum 48 h after challenge and lasted for at least 3 weeks. This hyperreactivity was not found in athymic (nude) mice. We conclude from these preliminary data that airway hyperreactivity can be immunologically induced other than by IgE, and that in this model it is not associated with the presence of a mononuclear infiltrate. These experimental data indicate a potential role for T cells in inducing airway hyperreactivity, a common denominator of patients suffering from asthma.

Migrating larvae of the canine nematode Toxocara canis induce inflammatory responses in the lungs of infected mice. Histological examination of the lungs showed that mice, developed persistent multifocal inflammation in which eosinophils (eos), macrophages (M phi) and many lymphocytes were involved. Cuffing of blood vessels and bronchioles with mixed cell populations was also observed. Investigation into the response of isolated tracheae to cholinergic and beta-adrenergic receptor agonists demonstrated a significant decreased reactivity despite the pronounced involvement of eos and M phi. This hyporeactive state persisted for greater than or equal to 4 weeks p.i..

We have studied delayed-type hypersensitivity (DTH) responses to picryl chloride (PCl) in the lungs of mice. Intranasal challenge with 0.6% picryl sulphonic acid (PSA), a water soluble form of PCl, of BALB/c mice, sensitized with PCl epicutaneously 1 week earlier, induced an accumulation of mononuclear inflammatory cells around bronchioli and blood vessels. Maximal inflammatory responses were seen 48 hr after challenge. These responses were antigen-specific, and also T-cell dependent, since athymic nude mice failed to show this reaction. A role for mast cells in the responses was studied using two strains of mast cell-deficient mice. In one of these (W/Wv) lung DTH responses to PCl were reduced severely. In the other strain (S1/S1d) the responses around vessels were decreased slightly, whereas the responses in the interstitial tissue and around bronchioli were similar to those in +/+ littermate controls. Involvement of serotonin was investigated using two serotonin receptor antagonists, i.e. methysergide and ketanserin. Treatment of mice with either of the antagonists prevented occurrence of the DTH-like reaction in the lung after intranasal antigen challenge. In the lungs of sensitized mice, significantly increased permeability was established 2 hr after antigen challenge. It was concluded that release of serotonin in the lung may provide an environment that comprises local vascular permeability and that facilitates the local recruitment and possibly the activation of DTH effector T cells, leading to subsequent attraction of mononuclear leucocytes into the lung. Immunological regulation of the DTH-like reactions in the lung was similar to that of contact sensitivity in the skin, since intravenous injection of an antigen-specific T-cell suppressor inducer factor prior to sensitization or pretreatment with a high dose of picryl sulphonic acid intravenously both resulted in reduction of the DTH-like lung histological response to picryl sulphonic acid. From these findings it was concluded that DTH-like lung responses are similar to DTH responses in the skin.