Effect of inhalation therapy with beclomethasone dipropionate on unspecific bronchial hyperreactivity in patients with asthma]

An effect of beclomethasone dipropionate (Beclocort-Polfa) was investigated in the group of 24 patients with atopic and non-atopic bronchial asthma who have shown unspecific bronchial hyperreactivity to histamine during the periods of remission. The drug was administered in the form of aerosol in a daily dose of 1.0 mg for 4 weeks. Provocative histamine dose was established with Bronchoscreen device (Jaeger) thrice:prior to the treatment, after 1 week of placebo therapy, and after 1 month of beclomethasone administration. Statistically significant increase in histamine dose for provocation of bronchospasm (p < 0.01) being nearly twice higher than the baseline value has been noted in patients treated with beclomethasone dipropionate aerosol. It advocates such a treatment in unspecific bronchial hyperreactivity independently of the type of the bronchial asthma.     

B7-H3 contributes to the development of pathogenic Th2 cells in a murine model of asthma

B7-H3 is a new member of the B7 family. The receptor for B7-H3 has not been identified, but it seems to be expressed on activated T cells. Initial studies have shown that B7-H3 provides a stimulatory signal to T cells. However, recent studies suggest a negative regulatory role for B7-H3 in T cell responses. Thus, the immunological function of B7-H3 is controversial and unclear. In this study, we investigated the effects of neutralizing anti-B7-H3 mAb in a mouse model of allergic asthma to determine whether B7-H3 contributes to the development of pathogenic Th2 cells and pulmonary inflammation. Administration of anti-B7-H3 mAb significantly reduced airway hyperreactivity with a concomitant decrease in eosinophils in the lung as compared with control IgG-treated mice. Treatment with anti-B7-H3 mAb also resulted in decreased production of Th2 cytokines (IL-4, IL-5, and IL-13) in the draining lymph node cells. Although blockade of B7-H3 during the induction phase abrogated the development of asthmatic responses, B7-H3 blockade during the effector phase did not inhibit asthmatic responses. These results indicated an important role for B7-H3 in the development of pathogenic Th2 cells during the induction phase in a murine model of asthma.     

Differential role of IFN-gamma-inducible protein 10 kDa in a cockroach antigen-induced model of allergic airway hyperreactivity: systemic versus local effects

The ability of IFN-gamma to antagonize established Th2 type allergic responses is well documented. To investigate the role of IFN-gamma-inducible protein 10 kDa (IP10) in the allergic response, we chose to investigate the effect of IP10 neutralization on an established Th2 response. Systemic neutralization of IP10 at the time of allergen challenge increased airway hyperreactivity as well as airway eosinophil accumulation. Interestingly, IFN-gamma levels were markedly reduced in both the lung and peripheral lymph node following IP10 neutralization. Furthermore, the number of CXCR3(+)CD4(+) T cells was decreased in the peripheral lymph node following neutralization of IP10. Introduction of exogenous IP10 into the airway at the time of allergen challenge also dramatically increased eosinophil accumulation in the airway. Protein levels of IL-4, IL-5, and IL-13 were significantly increased in the lung following exogenous airway administration of IP10 with allergen. Interestingly, airway hyperreactivity was significantly decreased at early time points following concurrent IP10 and allergen challenge but rebounded at 24 and 48 h post allergen challenge. Although IP10 may initially be acting locally to dampen the allergic response, its ability to recruit eosinophils may ultimately supersede any immunomodulatory effect it may have in an established allergic response. These results suggest that while systemic levels of IP10 are beneficial in controlling the allergic response, possibly by regulating cellular trafficking in the lymph node, local administration of exogenous IP10 into an established allergic response may be detrimental.     

The epithelial anion transporter pendrin is induced by allergy and rhinovirus infection, regulates airway surface liquid, and increases airway reactivity and inflammation in an asthma model

Asthma exacerbations can be triggered by viral infections or allergens. The Th2 cytokines IL-13 and IL-4 are produced during allergic responses and cause increases in airway epithelial cell mucus and electrolyte and water secretion into the airway surface liquid (ASL). Since ASL dehydration can cause airway inflammation and obstruction, ion transporters could play a role in pathogenesis of asthma exacerbations. We previously reported that expression of the epithelial cell anion transporter pendrin is markedly increased in response to IL-13. Herein we show that pendrin plays a role in allergic airway disease and in regulation of ASL thickness. Pendrin-deficient mice had less allergen-induced airway hyperreactivity and inflammation than did control mice, although other aspects of the Th2 response were preserved. In cultures of IL-13-stimulated mouse tracheal epithelial cells, pendrin deficiency caused an increase in ASL thickness, suggesting that reductions in allergen-induced hyperreactivity and inflammation in pendrin-deficient mice result from improved ASL hydration. To determine whether pendrin might also play a role in virus-induced exacerbations of asthma, we measured pendrin mRNA expression in human subjects with naturally occurring common colds caused by rhinovirus and found a 4.9-fold increase in mean expression during colds. Studies of cultured human bronchial epithelial cells indicated that this increase could be explained by the combined effects of rhinovirus and IFN-gamma, a Th1 cytokine induced during virus infection. We conclude that pendrin regulates ASL thickness and may be an important contributor to asthma exacerbations induced by viral infections or allergens.     

Integrated signals between IL-13, IL-4, and IL-5 regulate airways hyperreactivity

In this investigation, we have examined the integrated relationship between IL-13, IL-4, and IL-5 for the development of airways hyperreactivity (AHR) in a model of asthma in BALB/c mice. Sensitization and aeroallergen challenge of both wild-type (WT) and IL-13 gene-targeted (IL-13-/-) mice induced allergic disease that was characterized by pulmonary eosinophilia and AHR to beta-methacholine. Although these responses in IL-13-/- mice were heightened compared with WT, they could be reduced to the level in nonallergic mice by the concomitant neutralization of IL-4. Mice in which both IL-4 and IL-13 were depleted displayed a marked reduction in tissue eosinophils, despite the development of a blood eosinophilia. Similar neutralization of IL-4 in WT mice only partially reduced AHR with no effect on tissue eosinophilia. In addition, neutralization of IL-5 in IL-13-/- mice, but not in WT mice, inhibited AHR, suggesting that tissue eosinophilia is linked to the mechanism underlying AHR only in the absence of IL-13. Additionally, mucus hypersecretion was attenuated in IL-13-/- mice, despite the persistence of AHR. Taken together, our data suggest both a modulatory role for IL-13 during sensitization and a proinflammatory role during aeroallergen challenge. The latter process appears redundant with respect to IL-4.     

IL-10- and IL-12-independent down-regulation of allergic sensitization by stimulation of CD40 signaling

Interaction between CD154 (CD40 ligand) on activated T lymphocytes and its receptor CD40 has been shown to be critically involved in the generation of cell-mediated as well as humoral immunity. CD40 triggering activates dendritic cells (DC), enhances their cytokine production, up-regulates the expression of costimulatory molecules, and induces their maturation. It is unknown how stimulation of CD40 during sensitization to an airborne allergen may affect the outcome of allergic airway inflammation. We took advantage of a mouse model of allergic asthma and a stimulatory mAb to CD40 (FGK45) to study the effects of CD40-mediated DC activation on sensitization to OVA and subsequent development of OVA-induced airway inflammation. Agonistic anti-CD40 mAb (FGK45) injected during sensitization with OVA abrogated the development of allergic airway inflammation upon repeated airway challenges with OVA. Inhibition of bronchial eosinophilia corresponded with reduced Th2 cytokine production and was independent of IL-12, as evidenced by a similar down-regulatory effect of anti-CD40 mAb in IL-12 p40-deficient mice. In addition, FGK45 equally down-regulated allergic airway inflammation in IL-10-deficient mice, indicating an IL-10-independent mechanism of action of FGK45. In conclusion, our results show that CD40 signaling during sensitization shifts the immune response away from Th2 cytokine production and suppresses allergic airway inflammation in an IL-12- and IL-10-independent way, presumably resulting from enhanced DC activation during sensitization.     

The pathophysiology of asthma

Because postmortem studies of humans provide little information on the initial pathophysiologic events in asthma, animal models have been developed. Recently the Ascaris-allergic rhesus monkey has provided an opportunity to examine the onset of pathophysiologic changes following challenge and to correlate them with airway structure. These studies have suggested that the initial interaction between antigen and mast cells may occur in the bronchial lumen or in the epithelium superficial to the tight junctions, where a small but significant percentage of airway mast cells exist. It also appears that this initial antigen-antibody interaction results in the release of mediators that both stimulate the rapidly adapting stretch receptors in the mucosa and alter the mucosal barrier so that proteins of large molecular weight can penetrate. The fact that antigen challenge results in hyperresponsiveness to a subsequent dose of inhaled histamine and increased systemic absorption of histamine suggests that the airway hyperresponsiveness could be related to increased penetration of histamine into the bronchial wall. These observations suggest that the initial event in an acute asthmatic attack is the release of mediators from superficial mast cells, and that this amplifies the allergic response by altering the mucosal permeability so that more antigen reaches the submucosal mast cells. This altered permeability may also help explain the hyperreactivity of the airways to nonspecific airway stimulants in persons with asthma.     

Cutting edge: histamine is required for IL-4-driven eosinophilic allergic responses

Histamine is an important allergic mediator, and studies have defined roles for both histamine 1 and 4 receptors in allergic airway inflammation. In this study, we show that histamine is necessary to generate IL-4-driven eosinophilic inflammation, as histamine-deficient mice cannot generate eosinophilic lung inflammation in response to intratracheal IL-4 and exogenous histamine restores responsiveness. This is histamine 2 receptor (H2R) dependent because H2R knockout mice fail to respond to IL-4, and a H2R agonist restores inflammation in histidine decarboxylase knockout. Furthermore, alveolar epithelial cells require H2R to produce CCL24, an eosinophil recruitment factor, whereas H2R blockade reduces CCL24 production from wild-type cells. In an allergic inflammation model, H2R knockout mice show significantly reduced eosinophilic inflammation and CCL24 expression. These data demonstrate a previously unidentified role for H2R in allergic inflammation and establishes a synergy between endogenous histamine and IL-4 that supports eosinophilic recruitment to the lung.     

CpG oligodeoxynucleotides can reverse Th2-associated allergic airway responses and alter the B7.1/B7.2 expression in a murine model of asthma

CpG oligodeoxynucleotides (CpG-ODN) administered during Ag sensitization or before Ag challenge can inhibit allergic pulmonary inflammation and airway hyperreactivity in murine models of asthma. In this study, we investigated whether CpG-ODN can reverse an ongoing allergic pulmonary reaction in a mouse model of asthma. AKR mice were sensitized with conalbumin followed by two intratracheal challenges at weekly intervals. CpG-ODN was administered 24 h after the first Ag challenge. CpG-ODN administration reduced Ag-specific IgE levels, bronchoalveolar lavage fluid eosinophils, mucus production, and airway hyperreactivity. We found that postchallenge CpG-ODN treatment significantly increased IFN-gamma concentrations and decreased IL-13, IL-4, and IL-5 concentrations in bronchoalveolar lavage fluids and spleen cell culture supernatants. Postchallenge CpG-ODN treatment also increased B7.1 mRNA expression and decreased B7.2 mRNA expression in lung tissues. These results suggest that CpG-ODN may have potential for treatment of allergic asthma by suppressing Th2 responses during IgE-dependent allergic airway reactions. The down-regulation of Th2 responses by CPG-ODN may be associated with regulation of the costimulatory factors B7.1 and B7.2.     

Cooperative effects of Th2 cytokines and allergen on normal and asthmatic bronchial epithelial cells

In sensitized individuals, exposure to allergens such as Dermatophagoides pteronyssinus (Der p) causes Th2 polarization and release of cytokines, including IL-4 and IL-13. Because Der p extracts also have direct effects on epithelial cells, we hypothesized that allergen augments the effects of Th2 cytokines by promoting mediator release from the bronchial epithelium in allergic asthma. To test our hypothesis, primary bronchial epithelial cultures were grown from bronchial brushings of normal and atopic asthmatic subjects. RT-PCR showed that each culture expressed IL-4R(alpha), common gamma-chain, and IL-13R(alpha)(1), as well as IL-13R(alpha)(2), which negatively regulates IL-13 signaling; FACS analysis confirmed IL-13R(alpha)(2) protein expression. Exposure of epithelial cultures to either Der p extracts, TNF-alpha, IL-4, or IL-13 enhanced GM-CSF and IL-8 release, and this was partially suppressible by corticosteroids. Simultaneous exposure of the epithelial cultures to IL-4 or IL-13 together with Der p resulted in a further increase in cytokine release, which was at least additive. Release of TGF-alpha was also increased by TNF-alpha and combinations of IL-4, IL-13, and Der p; however, this stimulation was only significant in the asthma-derived cultures. These data suggest that, in an allergic environment, Th2 cytokines and allergen have the potential to sustain airway inflammation through a cooperative effect on cytokine release by the bronchial epithelium. Our novel finding that IL-4, IL-13, and allergen enhance release of TGF-alpha, a ligand for the epidermal growth factor receptor that stimulates fibroblast proliferation and goblet cell differentiation, provides a potential link between allergen exposure, Th2 cytokines, and airway remodelling in asthma.     

Effect of inhaled endotoxin on bronchial reactivity in asthmatic and normal subjects

Endotoxins are released from the membrane of Gram-negative bacteria present in the environment and in oral and nasal cavities. They are proinflammatory substances that could participate in bronchial obstruction and hyperreactivity in asthmatic patients. This hypothesis was tested by using bronchial challenge tests with inhaled lipopolysaccharides (LPS) from Escherichia coli 026:B6 (22.2-micrograms total dose) followed by a histamine nonspecific challenge test and compared with a placebo procedure, in which the diluent was substituted for the LPS solution. In doing so we showed that LPS induces a slight but significant (P less than 0.01) bronchial obstruction (measured as forced expiratory volume in 1 s) in asthmatics (n = 8) but not in normal subjects (n = 6). The histamine hyperresponsiveness, expressed as the dosage of histamine necessary to decrease the bronchial specific conductance by 50%, was increased 5 h after LPS inhalation in asthmatics (P less than 0.05) but not in normal subjects. This effect of LPS on bronchial obstruction and hyperresponsiveness was observed in extrinsic (n = 6) as well as in intrinsic (n = 2) asthma.     

Serum levels of soluble IL-2R, CD4 and CD8 in bronChial asthma

The aim of the present study was to compare serum levels of soluble forms of interleukin-2 receptor, CD4 and CD8, released by lymphocytes during activation of the immune system, in patients with allergic bronchial asthma, with those in healthy subjects. Significantly higher levels of soluble IL-2R and soluble CD4 were found in patients with asthma compared with the control group. In contrast, lower levels of soluble CD8 values were found in patients with asthma compared to the control group. Significant correlations were found for both sIL-2R and sCD4 and these two molecules, with lung function measured as bronchial responsiveness to inhaled methacholine. These results strengthen previous suggestions that in allergic bronchial asthma, activation of T cells plays a significant role in the disease pathogenesis.     

The interaction of histamine with other bronchoconstrictor mediators

The lack of therapeutic efficacy of antihistaminic drugs in the treatment of asthma has led to the search and discovery of other bronchoconstrictor agents, particularly leukotrienes, thromboxanes, and platelet-activating factor. However, specific receptor antagonist for any of these substances have also not been particularly effective in inhibiting allergic bronchoconstriction. It is now generally accepted that histamine, arachidonic acid metabolites, platelet-activating factor, and possibly other substances are all involved to varying degrees in asthma and may indeed interact. This paper reviews the interaction of these mediators and how they contribute to airway hyperreactivity.     

Differential roles of IL-18 in allergic airway disease: induction of eotaxin by resident cell populations exacerbates eosinophil accumulation

Cytokine regulation during an allergic response can dictate the severity of the inflammation and resulting injury. In the present study, we have examined the systemic and local effects of IL-18, a Th1-associated cytokine, on a cockroach allergen-induced airway response. In initial studies, temporal increases in IL-18 levels were observed within the lungs. When IL-18 was neutralized systemically the allergen-associated eosinophil accumulation was significantly accelerated 5-fold by 8 h postchallenge, suggesting a regulatory role for IL-18. Recombinant IL-18 (200 ng) was instilled into the airway at the time of allergen challenge to examine whether a direct impact on local eosinophil accumulation could be induced. When IL-18 was instilled, a significant increase in peribronchial eosinophil accumulation was observed in allergic mice as well as in nonallergic mice. A possible mechanism was observed in a significant increase in eotaxin, but not other eosinophil chemotactic factors, in bronchoalveolar lavage fluid after IL-18 instillation. The role of eotaxin was confirmed using eotaxin -/- mice, which demonstrated significantly less eosinophil accumulation compared with littermate controls. IL-18 was subsequently shown to induce eotaxin production from bronchial epithelial cells and isolated macrophages in in vitro assays. The clinical relevance of these findings was determined in treated mice and demonstrated that neutralization of IL-18 exacerbated, whereas exogenous IL-18 had no effect on airway hyperreactivity. Altogether, these data demonstrate that IL-18 may have multiple functions during an immune response that differ depending upon the local or systemic effects.     

IL-2 receptor beta-chain signaling controls immunosuppressive CD4+ T cells in the draining lymph nodes and lung during allergic airway inflammation in vivo

IL-2 influences both survival and differentiation of CD4(+) T effector and regulatory T cells. We studied the effect of i.n. administration of Abs against the alpha- and the beta-chains of the IL-2R in a murine model of allergic asthma. Blockade of the beta- but not the alpha-chain of the IL-2R after allergen challenge led to a significant reduction of airway hyperresponsiveness. Although both treatments led to reduction of lung inflammation, IL-2 signaling, STAT-5 phosphorylation, and Th2-type cytokine production (IL-4 and IL-5) by lung T cells, IL-13 production and CD4(+) T cell survival were solely inhibited by the blockade of the IL-2R beta-chain. Moreover, local blockade of the common IL-2R/IL-15R beta-chain reduced NK cell number and IL-2 production by lung CD4(+)CD25(+) and CD4(+)CD25(-) T cells while inducing IL-10- and TGF-beta-producing CD4(+) T cells in the lung. This cytokine milieu was associated with reduced CD4(+) T cell proliferation in the draining lymph nodes. Thus, local blockade of the beta-chain of the IL-2R restored an immunosuppressive cytokine milieu in the lung that ameliorated both inflammation and airway hyperresponsiveness in experimental allergic asthma. These findings provide novel insights into the functional role of IL-2 signaling in experimental asthma and suggest that blockade of the IL-2R beta-chain might be useful for therapy of allergic asthma in humans.     

Bacterial lipopolysaccharide signaling through Toll-like receptor 4 suppresses asthma-like responses via nitric oxide synthase 2 activity

Asthma results from an intrapulmonary allergen-driven Th2 response and is characterized by intermittent airway obstruction, airway hyperreactivity, and airway inflammation. An inverse association between allergic asthma and microbial infections has been observed. Microbial infections could prevent allergic responses by inducing the secretion of the type 1 cytokines, IL-12 and IFN-gamma. In this study, we examined whether administration of bacterial LPS, a prototypic bacterial product that activates innate immune cells via the Toll-like receptor 4 (TLR4) could suppress early and late allergic responses in a murine model of asthma. We report that LPS administration suppresses the IgE-mediated and mast cell-dependent passive cutaneous anaphylaxis, pulmonary inflammation, airway eosinophilia, mucus production, and airway hyperactivity. The suppression of asthma-like responses was not due to Th1 shift as it persisted in IL-12(-/-) or IFN-gamma(-/-) mice. However, the suppressive effect of LPS was not observed in TLR4- or NO synthase 2-deficient mice. Our findings demonstrate, for the first time, that LPS suppresses Th2 responses in vivo via the TLR4-dependent pathway that triggers NO synthase 2 activity.     

The histamine H4 receptor mediates allergic airway inflammation by regulating the activation of CD4+ T cells

Histamine is an important inflammatory mediator that is released in airways during an asthmatic response. However, current antihistamine drugs are not effective in controlling the disease. The discovery of the histamine H4 receptor (H4R) prompted us to reinvestigate the role of histamine in pulmonary allergic responses. H4R-deficient mice and mice treated with H4R antagonists exhibited decreased allergic lung inflammation, with decreases in infiltrating lung eosinophils and lymphocytes and decreases in Th2 responses. Ex vivo restimulation of T cells showed decreases in IL-4, IL-5, IL-13, IL-6, and IL-17 levels, suggesting that T cell functions were disrupted. In vitro studies indicated that blockade of the H4R on dendritic cells leads to decreases in cytokine and chemokine production and limits their ability to induce Th2 responses in T cells. This work suggests that the H4R can modulate allergic responses via its influence on T cell activation. The study expands the known influences of histamine on the immune system and highlights the therapeutic potential of H4R antagonists in allergic conditions.     

Monocyte chemoattractant protein-1 mediates cockroach allergen-induced bronchial hyperreactivity in normal but not CCR2-/- mice: the role of mast cells.

Bronchial eosinophil and mononuclear cell infiltrates are a hallmark of the asthmatic lung and are associated with the induction of reversible airway hyperreactivity. In these studies, we have found that monocyte chemotactic protein-1 (MCP-1), a CC (beta) chemokine, mediates airway hyperreactivity in normal and allergic mice. Using a murine model of cockroach Ag-induced allergic airway inflammation, we have demonstrated that anti-MCP-1 Abs inhibit changes in airway resistance and attenuate histamine release into the bronchoalveolar lavage, suggesting a role for MCP-1 in mast cell degranulation. In normal mice, instillation of MCP-1 induced prolonged airway hyperreactivity and histamine release. In addition, MCP-1 directly induced pulmonary mast cell degranulation in vitro. These latter effects would appear to be selective because no changes were observed when macrophage-inflammatory protein-1alpha, eotaxin, or MCP-3 were instilled into the airways of normal mice or when mast cells were treated in vitro. Airway hyperreactivity was mediated by MCP-1 through CCR2 because allergen-induced as well as direct MCP-1 instilled-induced changes in airway hyperreactivity were significantly attenuated in CCR2 -/- mice. The neutralization of MCP-1 in allergic animals and instillation of MCP-1 in normal animals was related to leukotriene C4 levels in the bronchoalveolar lavage and was directly induced in pulmonary mast cells by MCP-1. Thus, these data identify MCP-1 and CCR2 as potentially important therapeutic targets for the treatment of hyperreactive airway disease.     

Pharmacological targeting of anaphylatoxin receptors during the effector phase of allergic asthma suppresses airway hyperresponsiveness and airway inflammation

Airway hyperresponsiveness and airway inflammation are hallmarks of allergic asthma, the etiology of which is crucially linked to the presence of Th2 cytokines. A role for the complement anaphylatoxins C3a and C5a in allergic asthma was suggested, as deficiencies of the C3a receptor (C3aR) and of complement factor C5 modulate airway hyperresponsiveness, airway inflammation, and Th2 cytokine levels. However, such models do not allow differentiation of effects on the sensitization phase and the effector phase of the allergic response, respectively. In this study, we determined the role of the anaphylatoxins on the effector phase of asthma by pharmacological targeting of the anaphylatoxin receptors. C3aR and C5a receptor (C5aR) signaling was blocked using the nonpeptidic C3aR antagonist SB290157 and the neutralizing C5aR mAb 20/70 in a murine model of Aspergillus fumigatus extract induced pulmonary allergy. Airway hyperresponsiveness was substantially improved after C5aR blockade but not after C3aR blockade. Airway inflammation was significantly reduced in mice treated with the C3aR antagonist or the anti-C5aR mAb, as demonstrated by reduced numbers of neutrophils and eosinophils in bronchoalveolar lavage fluid. Of note, C5aR but not C3aR inhibition reduced lymphocyte numbers in bronchoalveolar lavage fluid. Cytokine levels of IL-5 and IL-13 in bronchoalveolar lavage fluid were not altered by C3aR or C5aR blockade. However, blockade of both anaphylatoxin receptors markedly reduced IL-4 levels. These data suggest an important and exclusive role for C5aR signaling on the development of airway hyperresponsiveness during pulmonary allergen challenge, whereas both anaphylatoxins contribute to airway inflammation and IL-4 production.