Activation of CD4+ T cells, increased TH2-type cytokine mRNA expression, and eosinophil recruitment in bronchoalveolar lavage after allergen inhalation challenge in patients with atopic asthma

IL-4 promotes airway eosinophilia by suppressing IFN-gamma production: defining a novel role for IFN-gamma in the regulation of allergic airway inflammation

Airway eosinophilia in asthma is dependent on cytokines secreted by Th2 cells, including IL-5 and IL-4. In these studies we investigated why the absence of IL-4 led to a reduction in airway, but not lung tissue, eosinophils. Using adoptively transferred, in vitro-generated TCR-transgenic Th2 cells deficient in IL-4, we show that this effect is independent of IL-5 and Th2 cell generation. Airway eosinophilia was no longer inhibited when IL-4(-/-) Th2 cells were transferred into IFN-gammaR(-/-) mice, indicating that IFN-gamma was responsible for reducing airway eosinophils in the absence of IL-4. Intranasal administration of IFN-gamma to mice after IL-4(+/+) Th2 cell transfer also caused a reduction in airway, but not lung parenchymal, eosinophils. These studies show that IL-4 indirectly promotes airway eosinophilia by suppressing the production of IFN-gamma. IFN-gamma reduces airway eosinophils by engaging its receptor on hemopoietic cells, possibly the eosinophil itself. These studies capitalize on the complex counterregulatory effects of Th1 and Th2 cytokines in vivo and clarify how IL-4 influences lung eosinophilia. We define a new regulatory role for IFN-gamma, demonstrating that eosinophilic inflammation is differentially regulated at distinct sites within the respiratory tract.

Stress-induced increment on total bronchoalveolar cell count in OVA-sensitized rats

The influence of stress on total leukocyte count from bronchoalveolar lavage (BAL) was investigated in rats sensitized and challenged with ovalbumin (OVA). The animals were injected intraperitoneally with a suspension of OVA plus aluminum hydroxide in 0.9% NaCl (Day 0) and boosted at Day 7 with an identical OVA solution, administered subcutaneously. From the first to the 13th day after sensitization, rats were placed individually in a shuttle box where they received 50 escapable footshocks per day, always preceded by a sound signal (S); the responses that occurred during both S and shocks canceled the stressful stimulation. On Day 14, animals were submitted to a single session of 50 inescapable footshocks, preceded by the same S; immediately after, the animals were submitted to a 1% OVA-inhalation challenge. Results showed high levels of stress in the shocked animals as detected through both ultrasonic vocalizations (UVs) and social interaction test in an open field. Total leukocyte count in BAL from stressed animals (24 h post-OVA challenge) revealed a significant increase in the number of inflammatory cells in comparison to that measured in sensitized, nonstressed challenged rats. These data demonstrate that stress plays a relevant and important role on total bronchoalveolar cell count in OVA-sensitized rats.

Type 1/Type 2 immunity in infectious diseases

T helper type 1 (Th1) lymphocytes secrete secrete interleukin (IL)-2, interferon-gamma, and lymphotoxin-alpha and stimulate type 1 immunity, which is characterized by intense phagocytic activity. Conversely, Th2 cells secrete IL-4, IL-5, IL-9, IL-10, and IL-13 and stimulate type 2 immunity, which is characterized by high antibody titers. Type 1 and type 2 immunity are not strictly synonymous with cell-mediated and humoral immunity, because Th1 cells also stimulate moderate levels of antibody production, whereas Th2 cells actively suppress phagocytosis. For most infections, save those caused by large eukaryotic pathogens, type 1 immunity is protective, whereas type 2 responses assist with the resolution of cell-mediated inflammation. Severe systemic stress, immunosuppression, or overwhelming microbial inoculation causes the immune system to mount a type 2 response to an infection normally controlled by type 1 immunity. In such cases, administration of antimicrobial chemotherapy and exogenous cytokines restores systemic balance, which allows successful immune responses to clear the infection.

Low peripheral blood levels of the immunosuppressive cytokine interleukin 10 (IL-10) at the start of gonadotrophin stimulation indicates increased risk for development of ovarian hyperstimulation syndrome (OHSS)

Our hypothesis was that patients developing ovarian hyperstimulation syndrome (OHSS) might have a disturbed responsiveness or delayed activation of the immunosuppresive cytokine system. In a prospective cohort study, women (n=428) undergoing in vitro fertilisation (IVF) treatment were subjected to repeated blood sampling and collection of clinical data. Fifteen patients, who developed severe OHSS, were compared with matched (age, follicle numbers, pregnancy) control patients. Samples of serum and plasma were collected throughout the stimulation and up to 7 days after embryo transfer as well as during hospitalisation for OHSS. Levels of IL-4, IL-10, IL-13, oestradiol and progesterone were measured. Significantly lower levels of IL-10 were seen at the start of gonadotrophin stimulation in OHSS patients, with an increase seen after the development of OHSS. In these OHSS patients, a negative correlation between IL-10 levels and number of follicles at time of aspiration existed, but there were no correlations between steroid and IL-10 levels. Levels of IL-13 and IL-4 were low in both groups and did not change during stimulation. The lower levels of IL-10 at start of stimulation in OHSS patients, as compared with controls, may be of pathophysiological importance by allowing for an enhanced Th-1 type immune response during gonadotrophin stimulation and thereby increased and generalised inflammation. The increase in IL-10 after development of OHSS indicates that IL-10 at that time is induced in a systemic attempt to suppress the inflammation of OHSS.

Antigen-specific T cell tolerance down-regulates mast cell responses in vivo

Fel d I is the major cat allergen that induces asthma and allergic rhinitis in humans. To investigate the mechanism of allergic responses to this allergen, a mouse model was developed. Mice sensitized to chain 1 of Fel d I exhibited T cell responses, B cell responses, and mast cell responses when challenged with the protein. Subcutaneous injections of peptides containing the dominant T cell epitopes of the allergen induced T cell tolerance in presensitized mice. When challenged with the allergen intratracheally, these tolerized mice produced a decreased amount of histamine in vivo. The decrease in histamine release was not solely dependent on the reduction of allergen-specific IgE. These data show that mast cell activity in mice with an ongoing sensitivity to allergen can be regulated through peptide-induced T cell tolerance.

T-helper type 2 cell-directed therapy for asthma

Asthma is a chronic inflammatory disease of the bronchial airways. Current research in humans and animals suggests that T-helper type 2 (Th2) cells and the cytokines they elaborate cause many of the pathophysiologic abnormalities characteristic of the disease. We review the evidence implicating Th2 cells in asthma and discuss the cellular and molecular mechanisms that control Th2 cell differentiation in the respiratory tract. Based on the steps in Th cell development, we discuss how traditional therapies can modulate Th2 cell function. Furthermore, we explore newer immunomodulatory strategies to inhibit Th2 cell effects, including therapies that may block Th2 cell differentiation, neutralize cytokines, and redirect immune responses towards Th1 and away from Th2.

Allergen-induced airway hyperreactivity is diminished in CD81-deficient mice

We demonstrated previously that CD81(-/-) mice have an impaired Th2 response. To determine whether this impairment affected allergen-induced airway hyperreactivity (AHR), CD81(-/-) BALB/c mice and CD81(+/+) littermates were sensitized i.p. and challenged intranasally with OVA. Although wild type developed severe AHR, CD81(-/-) mice showed normal airway reactivity and reduced airway inflammation. Nevertheless, OVA-specific T cell proliferation was similar in both groups of mice. Analysis of cytokines secreted by the responding CD81(-/-) T cells, particularly those derived from peribronchial draining lymph nodes, revealed a dramatic reduction in IL-4, IL-5, and IL-13 synthesis. The decrease in cytokine production was not due to an intrinsic T cell deficiency because naive CD81(-/-) T cells responded to polyclonal Th1 and Th2 stimulation with normal proliferation and cytokine production. Moreover, there was an increase in T cells and a decrease in B cells in peribronchial lymph nodes and in spleens of immunized CD81(-/-) mice compared with wild-type animals. Interestingly, OVA-specific Ig levels, including IgE, were similar in CD81(-/-) and CD81(+/+) mice. Thus, CD81 plays a role in the development of AHR not by influencing Ag-specific IgE production but by regulating local cytokine production.

T lymphocytes in asthma: bronchial versus peripheral responses

Recent evidence points to the recruitment of T(H)2 cells, phenotype T lymphocytes, their activation, and the generation of T(H)2 cytokines, particularly IL-4 and IL-5, in both peripheral blood and bronchial mucosa of asthmatic patients, leading to local tissue eosinophilia and IgE-dependent mast-cell activation. Activation of T(H)2 T lymphocytes appears to be specific for asthma (as opposed to airway obstructive disease) and was shown to correlate with asthma severity as evidenced by the inverse correlation between CD25(+)/CD4(+) cells and peak expiratory flow rates. These findings support the fundamental importance of T-lymphocyte responses in bronchial asthma and delineate potential therapeutic strategies, such as broad-based immunosuppression versus a more selective approach targeted against CD4(+) T lymphocytes. The high efficacy of topical treatments (ie, inhalation) supports the notion that changes that are detectable in peripheral blood merely reflect a "spill-over" of local T-lymphocyte responses in the target organ. Conversely, the multiple systemic manifestations of allergy (such as allergic rhinitis and atopic dermatitis in atopic patients) support systemic therapeutic approaches.

Endogenous and exogenous IL-6 inhibit aeroallergen-induced Th2 inflammation

Chronic Th2-dominated inflammation and exaggerated IL-6 production are characteristic features of the asthmatic airway. To understand the processes that are responsible for the chronicity of this response and the role(s) of IL-6 in the regulation of airway Th2 inflammation, we compared the responses induced by OVA in sensitized wild-type mice, IL-6 deficient (-/-) mice, and transgenic mice in which IL-6 was overexpressed in the airway (CC10-IL-6 mice). When compared with wild-type mice, IL-6-/- mice manifest exaggerated inflammation and eosinophilia, increased levels of IL-4, IL-5, and IL-13 protein and mRNA, exaggerated levels of eotaxin, JE/monocyte chemoattractant protein-1, macrophage inflammatory protein-1alpha and -2, and mRNA, increased bronchoalveolar lavage (BAL) TGF-beta1, and exaggerated airway responses to aerosolized methacholine. In contrast, CC10-IL-6 mice, on both C57BL/6 and BALB/c backgrounds, manifest diminished inflammation and eosinophilia, decreased levels of IL-4, IL-5, and IL-13 protein and mRNA, and decreased levels of bronchoalveolar lavage TGF-beta1. IL-6 also decreased the expression of endothelial VCAM-1 and airway responsiveness to methacholine in these animals. These alterations in the IL-6-/- and CC10-IL-6 mice were not associated with significant decreases or increases in the levels of IFN-gamma, respectively. These studies demonstrate that endogenous and exogenous IL-6 inhibit aeroallergen-induced Th2 inflammation and that this inhibition is not mediated by regulatory effects of IFN-gamma. IL-6 may be an important anti-inflammatory, counterregulatory, and healing cytokine in the airway.

Attenuation of the allergen-induced late asthmatic reaction by cyclosporin A is associated with inhibition of bronchial eosinophils, interleukin-5, granulocyte macrophage colony-stimulating factor, and eotaxin

The allergen-induced late asthmatic reaction (LAR) is associated with increases in bronchial eosinophils and basophils as well as upregulation of several eosinophil active cytokines and C-C chemokines. Cyclosporin A (CsA) was previously shown to inhibit the LAR, but not the early asthmatic reaction (EAR), and this was associated with a decrease in blood eosinophils. For these reasons, we determined whether CsA inhibited the allergen-induced increases in bronchial eosinophils, basophils, eotaxin, interleukin-5 (IL-5), and granulocyte macrophage colony-stimulating factor (GM-CSF). Subjects with a demonstrable LAR underwent bronchoscopy with biopsy and bronchoalveolar lavage (BAL) at baseline and then were randomly allocated to receive either CsA (n = 13) or placebo (n = 11) before challenge. A second bronchoscopy was performed 24 h later. The LAR, but not the EAR, was significantly attenuated in the CsA group compared with placebo (p < 0.05). CsA significantly inhibited the allergen-induced increases in IL-5 (p = 0.02) and GM-CSF (p = 0. 0028) in mRNA+ cells in BAL, and in a mAB against human activated eosinophils (EG2+) (p = 0.0227). We conclude that inhibition of the LAR by CsA may be related to its inhibitory effects on eosinophil-associated cytokines and chemokines. The beneficial effect of CsA in asthma may also be the result of inhibition of eosinophil accumulation.

Interleukin-9 enhances interleukin-5 receptor expression, differentiation, and survival of human eosinophils

Interleukin-9 (IL-9) has been implicated in the pathogenesis of allergic disorders. To examine the interaction between IL-9 and eosinophils, we evaluated mature peripheral blood eosinophils for their expression of the specific α-subunit of the IL-9 receptor (IL-9R–α). The expression of IL-9R–α by human eosinophils was detected at the messenger RNA (mRNA) and protein levels by reverse transcriptase–polymerase chain reaction (RT-PCR), flow cytometry, and immunocytochemical analysis, respectively. Functional analyses demonstrated that recombinant human (rh)IL-9 inhibited in vitro peripheral blood human eosinophil apoptosis in a concentration-dependent manner. We then examined the role of IL-9 in eosinophil differentiation using the human cord blood CD34+cells and human promyelocytic leukemia cells (HL-60). The addition of IL-9 to CD34+ cells cultured in IL-3 and IL-5 enhanced eosinophil development, and IL-9 alone induced the expression of IL-5R–α. IL-9 also up-regulated the IL-5R–α chain cell surface expression during terminal eosinophil differentiation of the HL-60 cell line. Our findings suggest that IL-9 may potentiate in vivo eosinophil function by increasing their survival and IL-5–mediated differentiation and maturation. Taken together, these results suggest a mechanism by which IL-9 potentiates airway and tissue eosinophilia.

Interleukin-9 enhances interleukin-5 receptor expression, differentiation, and survival of human eosinophils

Interleukin-9 (IL-9) has been implicated in the pathogenesis of allergic disorders. To examine the interaction between IL-9 and eosinophils, we evaluated mature peripheral blood eosinophils for their expression of the specific α-subunit of the IL-9 receptor (IL-9R–α). The expression of IL-9R–α by human eosinophils was detected at the messenger RNA (mRNA) and protein levels by reverse transcriptase–polymerase chain reaction (RT-PCR), flow cytometry, and immunocytochemical analysis, respectively. Functional analyses demonstrated that recombinant human (rh)IL-9 inhibited in vitro peripheral blood human eosinophil apoptosis in a concentration-dependent manner. We then examined the role of IL-9 in eosinophil differentiation using the human cord blood CD34+cells and human promyelocytic leukemia cells (HL-60). The addition of IL-9 to CD34+ cells cultured in IL-3 and IL-5 enhanced eosinophil development, and IL-9 alone induced the expression of IL-5R–α. IL-9 also up-regulated the IL-5R–α chain cell surface expression during terminal eosinophil differentiation of the HL-60 cell line. Our findings suggest that IL-9 may potentiate in vivo eosinophil function by increasing their survival and IL-5–mediated differentiation and maturation. Taken together, these results suggest a mechanism by which IL-9 potentiates airway and tissue eosinophilia.

T cells from human allergen-induced late asthmatic responses express IL-12 receptor beta 2 subunit mRNA and respond to IL-12 in vitro

IL-12 suppresses proallergic Th2-type cytokine production and induces Th1-type cytokine production by peripheral blood T cells from subjects with allergic disease. The objective of the present study was to examine the relevance of these findings to target organ T cell responses in human asthma. Bronchoalveolar lavage (BAL) and PBMC were collected from atopic asthmatics 24 h after fiberoptic allergen challenge of a segmental bronchus. BAL T cells and PBMC were cultured with allergen in the presence of recombinant IL-12 or IFN-gamma, and cytokines were measured in culture supernatants after 6 days. IL-5 production by BAL T cells and PBMC was inhibited by IL-12 and, to a lesser extent, by IFN-gamma. IL-12 also induced IFN-gamma production by BAL T cells and PBMC. The effects of IL-12 nor IFN-gamma on IL-5 production could not be reversed by neutralizing anti-IFN-gamma or anti-IL-12 mAbs, respectively. Thus, the effect of neither IL-12 nor IFN-gamma appeared to be mediated through induction of the other cytokine. In situ hybridization revealed that approximately one-third of BAL T cells expressed mRNA transcripts encoding the IL-12R beta 2 subunit following allergen challenge. Thus, human T cells obtained from BAL during asthmatic late responses, like T cells in the peripheral circulation, remain susceptible to immunomodulation by IL-12. These findings raise the possibility that IL-12 may hold therapeutic potential in allergic diseases such as asthma.

Animal models of asthma: potential usefulness for studying health effects of inhaled particles

Asthma is now recognized to be a chronic inflammatory disease that affects the whole lung. Incidence appears to be increasing despite improved treatment regimens. There is substantial epidemiological evidence suggesting a relationship between the incidence and severity of asthma (e.g., hospitalizations) and exposure to increased levels of air pollution, especially fine and ultrafine particulate material, in susceptible individuals. There have been a few studies in animal models that support this concept, but additional animal studies to test this hypothesis are needed. However, such studies must be performed with awareness of the strengths and weaknesses of the currently available animal models. For studies in mice, the most commonly used animal, a broad spectrum of molecular and immunological tools is available, particularly to study the balance between Th1 and Th2 responses, and inbred strains may be useful for genetic dissection of susceptibility to the disease. However, the mouse is a poor model for bronchoconstriction or localized immune responses that characterize the human disease. In contrast, allergic lung diseases in dogs and cats may more accurately model the human condition, but fewer tools are available for characterization of the mechanisms. Finally, economic issues as well as reagent availability limit the utility of horses, sheep, and primates.

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.

IL-9 expression by human eosinophils: regulation by IL-1beta and TNF-alpha

BACKGROUND

IL-9 is a pleiotropic cytokine that exhibits biologic activity on cells of diverse hemopoietic lineage. IL-9 stimulates the proliferation of activated T cells, enhances the production of IgE from B cells, and promotes the proliferation and differentiation of mast cells and hematopoietic progenitors.

OBJECTIVE

In this study we evaluated the expression of IL-9 messenger (m)RNA and protein by human peripheral blood eosinophils. We also investigated the role of IL-1beta and TNF-alpha in the release of IL-9 from human peripheral blood eosinophils.

METHODS

RT-PCR, in situ hybridization, and immunocytochemistry were used to investigate the presence of IL-9 mRNA and protein in human peripheral blood eosinophils from asthmatic patients and normal control subjects. Furthermore, biologic assay was used to investigate the release of IL-9 protein from IL-1beta- or TNF-alpha-stimulated eosinophils in vitro.

RESULTS

RT-PCR analysis showed the presence of IL-9 mRNA in human peripheral blood eosinophil RNA preparations from subjects with atopic asthma, as well as in the eosinophil-differentiated HL-60 cell line. By using in situ hybridization, a significant difference (P <.01) in IL-9 mRNA expression was detected in human peripheral blood eosinophils freshly isolated from asthmatic subjects compared with those isolated from normal control subjects. Furthermore, the percentage of IL-9 immunoreactive eosinophils from asthmatic patients was increased compared with that found in normal control subjects (P <.01). We also demonstrate that cultured human peripheral blood eosinophils from asthmatic subjects synthesize and release IL-9 protein, which is upregulated on stimulation with TNF-alpha and IL-1beta.

CONCLUSION

Human eosinophils express biologically active IL-9, which suggests that these cells may influence the recruitment and activation of effector cells linked to the pathogenesis of allergic disease. These observations provide further evidence for the role of eosinophils in regulating airway immune responses.

Increased expression of IL-16 immunoreactivity in bronchial mucosa after segmental allergen challenge in patients with asthma

BACKGROUND

We have previously shown increased expression of the CD4(+) cell chemoattractant IL-16 in bronchial mucosa of patients with asthma. We investigated the effects of allergen challenge on airway IL-16 expression.

METHODS

We investigated the expression of IL-16 immunoreactivity in bronchial biopsy samples obtained from atopic asthmatic subjects (n = 19) and normal subjects (n = 6) 24 hours after segmental allergen challenge. Control biopsy samples were obtained either at baseline or after diluent challenge. IL-16 expression was correlated to numbers of CD4(+) cells, CD25(+) cells, and activated eosinophils. IL-16 bioactivity was assessed in bronchoalveolar fluid obtained from patients with asthma.

RESULTS

IL-16 expression was higher in control biopsy specimens obtained from subjects with asthma compared with normal subjects (P<.05). In patients with asthma, numbers of IL-16 immunoreactive cells were significantly higher in biopsy specimens obtained after allergen challenge compared with control biopsy specimens (P<.001). Allergen provocation was associated with release of IL-16 in bronchoalveolar fluid in patients with asthma. In normal subjects, there was no difference in the number of IL-16-immunoreactive cells in biopsy specimens obtained after allergen challenge compared with biopsy specimens obtained after diluent challenge. Allergen challenge was associated with an increase in the numbers of EG2(+) eosinophils in patients with asthma but not in normal subjects. IL-16 expression correlated with the numbers of CD4(+) cells and CD25(+) cells after allergen challenge in asthmatic subjects with a provocative concentration required to decrease the FEV(1) by 20% of its baseline value (PC(20)FEV(1)) < 4 mg/mL. IL-16-immunoreactive cells were identified mainly as T cells and eosinophils in asthmatic subjects after allergen challenge.

CONCLUSION

Endobronchial allergen provocation in atopic asthmatic patients resulted in increased airway expression of IL-16 and release of bioactive IL-16 in airways. IL-16 may contribute to the immunoregulation of the inflammatory infiltrate in the airways in response to antigen.

Control of IL-5 production by human helper T cells as a treatment for eosinophilic inflammation: comparison of in vitro and in vivo effects between selective and nonselective cytokine synthesis inhibitors

BACKGROUND

Helper T cells are involved in the pathophysiologic condition of asthma, so modulation of cytokine production may be effective therapy.

OBJECTIVE

We aimed to selectively control the synthesis of IL-5 by helper T cells and tested in vivo effects using a murine asthma model.

METHODS

The effect of dexamethasone, FK506, cyclosporin A, and nonactin (a macrolide compound produced by Streptomyces griseus) on cytokine production by allergen-specific T-cell clones was determined. The effect of these agents and an anti-IL-5 neutralizing antibody on airway eosinophilic inflammation was investigated in a murine asthma model.

RESULTS

Dexamethasone, FK506, and cyclosporin A suppressed the production of IL-2, IL-4, and IL-5 by human helper T cells, which shows a similar concentration-response relationship in each case. Cyclosporin A and dexamethasone inhibited airway eosinophilia in vivo. Nonactin suppressed IL-5 synthesis but not IL-2 or IL-4 synthesis, and it also significantly suppressed airway eosinophilia.

CONCLUSION

Nonactin only suppressed IL-5 synthesis and was as effective against eosinophilia as cyclosporin A and dexa-methasone, which indicates that IL-5 is a reasonable therapeutic target in allergic disorders that are accompanied by eosinophilic inflammation.

The pathology of chronic asthma

Our understanding of the pathophysiology of asthma has undergone great advances in the past decade, particularly with the recognition of cytokines and the roles they may take in orchestrating the local immune response. With this information, it has been possible to target new therapeutic entities such as cytokine or chemokine receptors. Eosinophils and T lymphocytes have a special place in the inflammatory and structural alterations contributing to the asthmatic diathesis. It is possible that phenotype subsets of these cells exist and they hold the key to perpetuation of immunologic and physiologic abnormalities in asthma.

Characterization in mice of the immunological properties of five allergenic acid anhydrides

Occupational exposure to certain acid anhydrides, including trimellitic anhydride (TMA), maleic anhydride (MA), phthalic anhydride (PA), hexahydrophthalic anhydride (HHPA) and methyltetrahydrophthalic anhydride (MTHPA), has been associated with the development of respiratory allergy or asthma. There is considerable debate about the mechanisms through which such chemicals may cause respiratory sensitization, particularly concerning a universal requirement for specific IgE antibody. Despite the controversy regarding an obligatory role for IgE, there is a growing consensus that chemical respiratory hypersensitivity is associated with the selective development of T lymphocytes with a type 2 (Th2) phenotype. In the current investigations we have characterized in mice the nature of immune responses provoked by prolonged topical exposure to five acid anhydrides. Under application conditions where similar overall immunogenicity was achieved, we have compared cytokine responses induced by PA, MA, HHPA and MTHPA with those provoked by concurrent exposure to TMA or to the reference contact allergen 2, 4-dinitrochlorobenzene (DNCB). Lymph node cells (LNC) draining the site of topical exposure to DNCB invariably expressed high levels of the type 1 cytokines interferon-gamma (IFN-gamma) and interleukin-12 (IL-12), but only low levels of the type 2 cytokines interleukin-4 (IL-4) and interleukin-10 (IL-10). In each experiment, TMA-activated LNC displayed the converse, type 2, phenotype of cytokine production. The other acid anhydrides in each case provoked a type 2 cytokine secretion profile, with comparable IL-10 expression but somewhat less vigorous IL-4 production compared with that observed following exposure to the reference respiratory allergen TMA. In every experiment relatively low levels of IFN-gamma and IL-12 were elaborated by acid anhydride-activated LNC, with the exception of PA-stimulated LNC that displayed increased amounts of IL-12 in comparison with other acid anhydrides. Thus, prolonged topical exposure of mice to five different acid anhydrides in each case resulted in the development of a predominantly Th2-type cytokine secretion phenotype, consistent with the ability of these materials to provoke asthma and respiratory allergy through a type 2 (possibly IgE-mediated) mechanism. Taken together with the results of previous investigations with a wider range of chemical allergens, these data suggest that induced cytokine secretion patterns or 'fingerprints' allow discrimination between contact and respiratory allergens and consequently represent a suitable approach to prospective evaluation of respiratory sensitization hazard.

Sputum cysteinyl leukotrienes increase 24 hours after allergen inhalation in atopic asthmatics

We have used the relatively noninvasive technique of induced sputum to measure allergen-induced changes in the concentration of eicosanoid mediators in bronchial secretions from atopic asthmatics. Sputum induction was performed before and 24 h after inhalational allergen challenge in 14 atopic asthmatics who developed a late asthmatic reaction (LAR). Differential cell counts were made on sputum cytospins and eicosanoid (cysteinyl leukotrienes [cys LTs], prostaglandin D(2) [PGD(2)], and PGE(2)) concentrations were measured in the sputum supernatants. The percentage of eosinophils at baseline correlated with the concentration of cys LTs (r = 0.84, p < 0.001) but not prostanoid mediators. Allergen challenge produced a significant increase in the concentration of sputum cys LTs from 3. 45 ng/ml sputum to 11.95 ng/ml (p = 0.002), which correlated with the increase in sputum eosinophils (r = 0.55, p < 0.05). There were no significant changes in PGD(2) or PGE(2) concentrations in sputum supernatants in response to challenge. Thus, the noninvasive technique of induced sputum has been used to demonstrate increased cys LTs, but not prostanoids associated with LAR after allergen challenge. The correlation between eosinophil numbers and cys LT concentrations at baseline values and 24 h after allergen challenge is consistent with these cells being a principal source of cys LTs within the airways at these time points.

Reproducibility of early and late asthmatic responses to allergen challenge in a large group of asthmatics

The specific bronchial provocative test (sBPT) coupled with allergen is used to investigate asthma. Very few studies have examined the reproducibility of responses to allergen challenge. The aim of this study was to measure the reproducibility of PD20FEV1 allergen and late asthmatic response (LAR) in 53 asthmatics and to relate the reproducibility to the time interval between two allergen challenges. Fifty-three atopic asthmatics performed two allergen challenges not less than 2 and not more than 26 weeks apart. Randomly, 19 subjects were assigned to a short-interval group (14-35 days between the two tests) and 34 to a long-interval group (40-180 days). In each challenge, the PD20FEV1 was sought for and the maximum % fall in FEV1 from 3 to 7 h after the allergen challenge was evaluated as a measurement of magnitude of the LAR. High intraclass correlation coefficients (R(I)) were found for both PD20FEV1 (R(I) = 0.78) and LAR (R(I) = 0.77) in all subjects. PD20FEV1 allergen showed a high R(I) in the long-interval group (R(I) = 0.80), but a low R(I) in the short-interval group (R(I) = 0.63). In contrast LAR showed a lower R(I) in the long-interval group (R(I) = 0.68) than in the short-interval group (R(I) = 0.77). Moreover, the R(I) for PD20FEV1 was particularly low in subjects with a dual pattern to the allergen challenge and a short interval between the two allergen challenges. Our study confirmed that asthmatic responses induced by allergen challenge have a good reproducibility. Moreover, we have demonstrated that the interval between two allergen challenges can determine a change in reproducibility in asthmatic responses induced by allergen challenge.

Baseline airway hyperreactivity in A/J mice is not mediated by cells of the adaptive immune system

Human asthma is characterized by increased airway hyperreactivity to a variety of bronchoconstricting agents. Aberrant type 2 immune responses in the lung have been associated with airway hyperreactivity in both human asthma and in murine models of allergic airways disease. Despite their intrinsically elevated basal airway reactivity to smooth muscle constricting agents, A/J mice demonstrated no inherent inflammatory cell infiltration nor elevation of type 2 cytokines in the lung. Crossed bone marrow reconstitution experiments between A/J and MHC congenic B10.A mice revealed enhanced airway reactivity only in A/J recipients, irrespective of whether they had been reconstituted with A/J or B10. A hemopoietic cells. Further, A/J-derived bone marrow cells did not affect the reactivity of B10.A recipients. Although mice on RAG-deficient and IL-4-deficient backgrounds demonstrate substantial abrogation of allergen-induced airway hyperreactivity, these gene deletions had no impact on the elevated baseline reactivity when backcrossed onto A/J mice. Thus, in these mice, basal airway hyperreactivity is maintained independently of type 2 immunity induced by allergens.

Effects of CpG DNA on Th1/Th2 balance in asthma

Thus, in our studies, we demonstrated that CpG ODN are effective in preventing the development of eosinophilic airway inflammation and bronchial hyper-reactivity in a murine model of asthma. Antigen-associated elevation of serum IgE levels is also suppressed. CpG ODN, administered in conjunction with antigen, is also effective in down-regulation of established Th2 responses. This protection is neither murine strain-dependent nor model-dependent. Although these effects of CpG ODN are associated with the induction of the Th1 cytokines IFN-gamma and IL-12, neither cytokine is absolutely required for the protection. These results suggest that CpG ODN may be an effective immunomodulatory agent in the treatment, and possibly prevention, of asthma.

Increase in CD45RO+ cells and activated eosinophils in chronic allergic conjunctivitis

We assessed the infiltration of CD45RO+ cells in conjunctival biopsies of fifteen subjects affected by seasonal allergic conjunctivitis by means of immunohistochemistry. Correlations between infiltration of CD45RO+ cells and serum and mucosal indices of eosinophilic activation were investigated. The study was performed in autumn and all selected patients showed <<red eyes>> also in absence of sensitising pollens. Fifteen healthy subjects were used as controls. The semi-quantitative count of CD45RO+ cells in biopsy specimens demonstrated that positive cells were higher in allergic patients than in controls (p < 0.001) and EG2+ eosinophils were present only in biopsies of allergic patients. Furthermore, a statistically significant positive correlation (r = 0.73; p < 0.001) between CD45RO+ lymphocytes and EG2 positive eosinophils, was observed in the biopsies of allergic patients. Total serum IgE significantly correlated with CD45RO+ cells (r = 0.61; p < 0.02) and EG2+ eosinophils (r = 0.67; p < 0.01) in the conjunctiva. On the other hand serum ECP did not correlate with any histological and immunohistochemical parameters in the conjunctival biopsies. The present study shows that mild symptoms in SCA patients out of pollen season are associated with inflammation of the conjunctiva as shown by an increased number of CD45RO and EG2 positive cells.

Th2 responses induced by epicutaneous or inhalational protein exposure are differentially dependent on IL-4

Atopic individuals are predisposed to mounting vigorous Th2-type immune responses to environmental allergens. To determine the factors responsible, animal models that closely mimic natural modes of allergen exposure should prove most informative. Therefore, we investigated the role of IL-4, a known Th2-promoting cytokine, in generation of Th2 responses after exposure of either the skin or airway to soluble protein. Compared with wild-type (WT) mice, IL-4-deficient (IL-4(-/-)) mice showed markedly impaired Th2 activation after primary exposure to inhaled ovalbumin (OVA), with decreased OVA-specific IgG1 and IgE, and significantly fewer eosinophils in bronchoalveolar lavage (BAL) fluid after airway challenge. In contrast, IL-4(-/-) mice initially exposed to epicutaneous (e.c.) OVA mounted Th2 responses equivalent to responses in WT mice, with high numbers of eosinophils in BAL fluid. Because Th2 responses were not induced by e.c. OVA exposure in Stat6(-/-) mice (mice lacking signal transducer and activator of transcription 6), the role of IL-13 was tested. In vivo depletion of IL-13 prevented Th2 responses induced by e.c. OVA exposure in IL-4(-/-) mice. These data demonstrate a marked difference in the IL-4 dependence of Th2 responses generated at two anatomic sites of natural allergen encounter and identify the skin as a particularly potent site for Th2 sensitization.

IFN-gamma-inducing factor (IL-18) increases allergic sensitization, serum IgE, Th2 cytokines, and airway eosinophilia in a mouse model of allergic asthma

We investigated the effects of IFN-gamma-inducing factor (IL-18) in a ragweed (RW) mouse model of allergic asthma. Administration of IL-18 in conjunction with allergic sensitization and challenge in wild-type, but not IFN-gamma -/- mice, inhibited the bronchoalveolar lavage (BAL) eosinophilia induced by RW challenge, and increased serum levels of RW-specific IgG2a and production of IFN-gamma from splenocytes cultured with RW, indicating a critical role for IFN-gamma in mediating these effects. Paradoxically, the same treatment schedule in WT mice increased serum levels of RW-specific IgE and IgG1, and production of IL-4 and IL-5 from splenocytes cultured with RW. When the effects of the same IL-18 treatment schedule were allowed to mature for 3 wk, the inhibition of lung eosinophil recruitment was replaced by augmentation of lung eosinophil recruitment. In another experiment, IL-18 administered only with allergic sensitization increased BAL eosinophilia and lung expression of IL-5 and IFN-gamma, while IL-18 administered only with RW challenge decreased BAL eosinophilia and increased lung IFN-gamma expression, while lung expression of IL-5 remained unchanged. IL-18 administered without RW or adjuvant to naive mice increased total serum IgE levels. Finally, intrapulmonary administrations of IL-18 plus RW in naive mice dramatically increased Th2 cytokine production, IgE levels, eosinophil recruitment, and airway mucus, demonstrating induction of allergic sensitization. This is the first report demonstrating that IL-18 promotes a Th2 phenotype in vivo, and potently induces allergic sensitization. These results suggest that IL-18 may contribute to the pathogenesis of allergic asthma.

Regulation of T-helper type 2 cell and airway eosinophilia by transmucosal coadministration of antigen and oligodeoxynucleotides containing CpG motifs

The characteristic features of bronchial asthma, including airway eosinophilia and elevated immunoglobulin (Ig)E levels, are known to be orchestrated by T-helper (Th) 2 cells. Oligodeoxynucleotides containing CpG motifs (CpG) have recently been highlighted as an immunomodulator that biases toward a Th1-dominant phenotype. However, CpG may incur nonspecific Th1 activation and toxic effects. In this study we report a novel inhibition of Th2 cells by transmucosal inoculation of antigen and CpG. Intratracheal instillation of CpG inhibited airway eosinophilia and Th2 cytokine production in antigen-sensitized mice. The inhibition was observed when CpG was given at the same time or in advance of antigen challenge. Notably, concomitant administration of CpG and antigen (as opposed to either one alone) was essential for the inhibitory effects. The antigen dose could be minimized to avoid a harmful boost of eosinophilia. CpG had few effects on systemic anti-ovalbumin IgE responses. These results demonstrate that a synergism between transmucosally administered allergen and CpG inhibits Th2 cells in parallel with an improvement in airway eosinophilia and hyperresponsiveness without impeding systemic immune responses. Our data imply that inhalation of a minimal amount of allergen plus CpG could be a novel desensitization therapy for patients with bronchial asthma.

Lymphocytes migrate from the blood into the bronchoalveolar lavage and lung parenchyma in the asthma model of the brown Norway rat

Lymphocyte migration from the blood into the lung has been suggested as being responsible for the increase of lymphocytes, in particular CD4 T cells, in the bronchoalveolar lavage (BAL) and bronchial mucosa in human asthma, but so far there has been no direct proof. We studied lymphocyte immigration and lymphocyte subpopulations in three lung compartments in ovalbumin (OVA)-sensitized and -challenged brown Norway (BN) rats. Increased numbers of CD4 and interleukin 2 (IL-2) receptor-positive T cells were found in the BAL and lung parenchyma in treated animals, but also increased numbers of CD8 T cells, B cells, and natural killer (NK) cells. For direct proof of lymphocyte migration from the blood into the lung, leukocytes were labeled with a fluorescent dye, 5- (and 6-) carboxyfluorescein-diacetate-succinimidyl-ester (CFSE), and injected intravenously immediately prior to OVA aerosol challenge. One day after challenge the number of CFSE(+), i.e., newly immigrated lymphocytes, was determined by flow cytometry gated on the lymphocyte cluster. A 15 times (1.5 times) higher number of CFSE(+) lymphocytes was found in the BAL (the lung parenchyma) of treated animals in comparison with control rats. In the BAL 51.8% of CFSE(+) cells were CD4-positive (parenchyma 72.7%) and 29.4% IL-2 receptor-positive (parenchyma 34.2%). There was no difference whether the leukocytes for labeling and injection were obtained from untreated or from OVA-sensitized donor animals. Our data show that lymphocyte immigration is at least in part responsible for the increase in lymphocyte numbers in the BAL and lung parenchyma in this animal asthma model.

IL-9 and its receptor in allergic and nonallergic lung disease: increased expression in asthma

BACKGROUND

Bronchial asthma is a chronic inflammatory disease associated with genetic components. Recently IL-9 has been reported as a candidate gene for asthma and to be associated with bronchial hyperresponsiveness and elevated levels of total serum IgE.

OBJECTIVE

To investigate the contribution of IL-9 to the pathogenesis of asthma, we examined the expression of IL-9 and its receptor (IL-9R) in bronchial tissue from subjects with atopic asthma (n = 10), chronic bronchitis (n = 11), and sarcoidosis (n = 9) and from atopic (n = 7) and nonatopic (n = 10) healthy control subjects.

METHODS

Bronchial biopsy specimens were examined for the presence of IL-9 and IL-9R protein and messenger RNA (mRNA) by immunocytochemistry and in situ hybridization, respectively. To phenotype the cells expressing IL-9 in asthmatic tissue, combined in situ hybridization and immunocytochemistry was also performed.

RESULTS

There was a highly significant difference (P <.001) in the expression of IL-9 mRNA in asthmatic airways (20.6 +/- 4.0 cells/mm of basement membrane) compared with chronic bronchitis (5.6 +/- 4.4), sarcoidosis (2.5 +/- 1.8), atopic control subjects (7.7 +/- 2.2), and healthy control subjects (2.7 +/- 2.3). The number of IL-9 immunoreactive cells was also greater in asthmatic patients compared with the other groups (P <.05). Although the level of IL-9R mRNA expression did not differ in any of the groups (P >.05), IL-9R immunoreactivity was significantly higher in asthmatic compared with control subjects. Furthermore, IL-9 mRNA expression levels were also significantly correlated with FEV(1) (P <.05) and the airway responsiveness to methacholine producing a 20% fall in FEV(1) (P <. 01). The cells expressing IL-9 mRNA in asthmatic tissue were CD3(+) lymphocytes (68%), major basic protein(+) eosinophils (16%), and elastase(+) neutrophils (8%).

CONCLUSION

The results of this study demonstrate the potential of IL-9 to be a marker for atopic asthma and furthermore suggest an important role for this cytokine in the pathophysiologic mechanisms of this disease.

Beta-adrenergic modulation of human type-1/type-2 cytokine balance

BACKGROUND

Neuroendocrine mediators are increasingly recognized as immunomodulatory agents. Lymphocytes and monocytes express receptors for a variety of neuroendocrine mediators, including catecholamines. It has been reported that beta-adrenergic agonists decrease IFN-gamma production, with varying effects on IL-4 and IL-5 production.

OBJECTIVE

Our purpose was to determine the effects of catecholamines (including beta-adrenergic agonists) on the type-1/type-2 cytokine balance in tetanus-stimulated human PBMCs.

METHOD

Human PBMCs were stimulated with tetanus in the presence of epinephrine (EPI), norepinephrine, or terbutaline. IFN-gamma, IL-4, IL-5, and IL-10 levels in the supernatants were determined by ELISA.

RESULTS

PBMCs stimulated in the presence of EPI produced decreased levels of IFN-gamma and increased levels of IL-10, IL-4, and IL-5. A small decrease in IFN-gamma production and an increase in IL-10, IL-4, and IL-5 production were also observed with norepinephrine. Terbutaline induced similar alterations in the type-1/type-2 cytokine balance compared with EPI, indicating that the beta(2)adrenergic receptor is involved in these cytokine alterations. Furthermore, these cytokine alterations were blocked by propranolol. Finally, IL-12p70 prevented the cytokine alterations, suggesting that the mechanism of beta-adrenergic-induced cytokine alterations involves a decrease in IL-12.

CONCLUSION

beta-Adrenergic agonists induce a shift in the human type-1/type-2 cytokine balance toward a type-2 response. These data provide a potential mechanism to explain the paradoxical increase in asthma morbidity and mortality associated with the chronic use of scheduled dosing of short-acting beta-adrenergic agonists.

Effects of sodium cromoglycate on cytokine production following antigen stimulation of a passively sensitized human lung model

BACKGROUND

Interleukin-5 (IL-5) and tumor necrosis factor-alpha (TNF-alpha) play key roles in bronchial asthma. Sodium cromoglycate (DSCG) and dexamethasone (Dex) are used in the treatment of asthma as anti-inflammatory agents.

OBJECTIVE

We investigated whether DSCG inhibited the expression of IL-5 and TNF-alpha mRNA and proteins from isolated human lungs, and compared these findings with those of Dex.

METHODS

Human lung specimens were passively sensitized with sera from atopic patients, then preincubated in the presence of DSCG (10(-3), 10(-4), 10(-5) M) or Dex (10(-6) M) for 2 hours. The specimens were stimulated with Dermatophagoides antigen, then cultured for 48 hours. The supernatant was collected 1, 2, 4, 8, 24, and 48 hours to measure IL-5 and TNF-alpha by enzyme-linked immunosorbent assay. mRNA expression was examined by reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

Tumor necrosis factor-alpha protein reached a peak level at 4 hours (156.57 +/- 18.29 pg/mL). Dex decreased TNF-alpha protein to 31.86 +/- 4.67 pg/mL (P < .001). There was also a decrease of TNF-alpha protein to 107.43 +/- 14.25 pg/mL by 10(-4) MD SCG (P < .001). Antigenic stimulation also increased the release of IL-5 protein at 4 hours and the peak level was observed at 24 hours (150.29 +/- 19.12 pg/mL). Dex decreased IL-5 protein to 28.57 +/- 5.27 pg/mL (P < .0001), 10(-4) M DSCG also decreased to 111.57 +/- 15.28 pg/mL (P < .05). RT-PCR analysis showed persistence of IL-5 and TNF-alpha mRNA expression from 1 to 24 hour after antigen stimulation. Dex but not DSCG inhibited IL-5 and TNF-alpha mRNA levels.

CONCLUSION

Our results showed that DSCG significantly inhibited IL-5 and TNF-alpha production by human lung specimens, suggesting that it acts as an anti-inflammatory agent.

Molecular pathology of allergic disease: I: lower airway disease

Asthma is a complex disorder associated with eosinophil infiltration and the activation of T lymphocytes within the airways. Recent advances in the pathophysiologic mechanisms of asthma point to the importance of eosinophil-basophil progenitor cells and a family of transcription factors that underlie the development of T(H)2-type responses. Further research is needed to address the development of chronic inflammatory changes, the role of profibrotic cytokines, and especially their reliance on eosinophils in the lungs.

Fluticasone propionate-induced regulation of the balance within macrophage subpopulations

In asthma, treatment with inhaled corticosteroids reduces chronic peribronchial inflammation and restores the balance within macrophage subpopulations. This study investigates whether corticosteroids can regulate monocyte differentiation in vitro and thereby influence the balance of functionally distinct macrophages. Graded doses of fluticasone propionate (FP) were added to cultures of normal peripheral blood monocytes in the presence or absence of IL-4. Cells were harvested after 7 days' culture. Double immunofluorescence studies were performed on cytospins of differentiated macrophages using the MoAbs RFD1 and RFD7 to distinguish inductive and suppressive macrophages by their respective phenotypes. Macrophage function was determined by quantifying allostimulation in a mixed leucocyte reaction and by measuring tumour necrosis factor-alpha (TNF-alpha) production. FP reduced the number of mature cells with a D1+ antigen-presenting phenotype and up-regulated the development of cells with the D1/D7+ and D7+ phenotypes. Functionally, this was associated with reduced stimulation of T cell proliferation in a mixed leucocyte reaction (MLR). Fluticasone also reversed the increase in both D1+ expression and TNF-alpha production induced by IL-4. The effect of FP persisted for 24 h after removal of FP from the culture medium. These results suggest that FP treatment of asthmatics may have a direct beneficial effect by normalizing the macrophage subset imbalance that contributes to the chronic peribronchial inflammation present in this condition.

Allergen-induced IL-9 directly stimulates mucin transcription in respiratory epithelial cells

A hallmark of asthma is mucin overproduction, a condition that contributes to airway obstruction. The events responsible for mucin overproduction are not known but are thought to be associated with mediators of chronic inflammation. Others have shown that T-helper 2 (Th2) lymphocytes are required for mucous cell metaplasia, which then leads to mucin overproduction in animal models of allergy. We hypothesized that Th2 cell mediators are present in asthmatic airway fluid and directly stimulate mucin synthesis in airway epithelial cells. Results in cultured airway epithelial cells showed that samples of asthmatic fluid stimulated mucin (MUC5AC) synthesis severalfold more potently than non-asthmatic fluid. Consistent with this, lavage fluid from the airways of allergen-challenged dogs stimulated mucin synthesis severalfold more potently than that from non-allergen-challenged dogs. Fractionation of dog samples revealed 2 active fractions at <10 kDa and 30-100 kDa. Th2 cytokines in these molecular weight ranges are IL-9 (36 kDa), IL-5 (56 kDa), and IL-13 (10 kDa). Antibody blockade of ligand-receptor interaction for IL-9 (but not IL-5 or IL-13) inhibited mucin stimulation by dog airway fluid. Furthermore, recombinant IL-9, but not IL-5 or IL-13, stimulated mucin synthesis. These results indicate that IL-9 may account for as much as 50-60% of the mucin-stimulating activity of lung fluids in allergic airway disease.

p38 Mitogen-Activated Protein Kinase Regulates Human T Cell IL-5 Synthesis

Involvement of p38 mitogen-activated protein (MAP) kinase in human T cell cytokine synthesis was investigated. p38 MAP kinase was clearly induced in human Th cells activated through the TCR. SB203580, a highly selective inhibitor of p38 MAP kinase, inhibited the induction of p38 MAP kinase in human Th cells. Major T cell cytokines, IL-2, IL-4, IL-5, and IFN-γ, were produced by Der f 2-specific Th clones upon stimulation through the TCR. IL-5 synthesis alone was significantly inhibited by SB203580 in a dose-dependent manner, whereas the production of IL-2, IL-4, and IFN-γ was not affected. The proliferation of activated T cells was not affected. IL-5 synthesis of human Th clones induced upon stimulation with rIL-2, phorbol ester plus anti-CD28 mAb, and immobilized anti-CD3 mAb plus soluble anti-CD28 mAb was also suppressed by SB203580 in the same concentration response relationship. The results clearly indicated that IL-5 synthesis by human Th cells is dependent on p38 MAP kinase activity, and is regulated distinctly from IL-2, IL-4, and IFN-γ synthesis. Selective control of IL-5 synthesis will provide a novel treatment devoid of generalized immune suppression for bronchial asthma and atopic dermatitis that are characterized by eosinophilic inflammation.

Differences in cytokine production by peripheral blood mononuclear cells (PBMC) between patients with atopic dermatitis and bronchial asthma

It is widely accepted that type 2 helper T (Th2) lymphocytes play a crucial role in the pathogenesis of atopic dermatitis (AD) as well as bronchial asthma (BA). We measured the amounts of IL-5 and interferon-gamma (IFN-gamma) produced by PBMC upon stimulation with house dust mite (HDM) or Candida albicans (CA) in 17 children (3-15 years) with AD, and compared these values with those of 16 children with BA. Although IL-5 production by PBMC upon stimulation with HDM in patients with AD was significantly higher than that in 13 non-atopic controls (geometric mean = 23.4 pg/ml versus 5.9 pg/ml, P < 0.05), it was significantly lower than that in patients with BA (177.8 pg/ml, P < 0.001). The amount of IL-5 produced by PBMC upon stimulation with CA was also significantly lower in patients with AD than in those with BA (7.2 pg/ml versus 100.0 pg/ml, P < 0.001). The production of IFN-gamma by PBMC stimulated with HDM or CA was also significantly lower in patients with AD than in those with BA (HDM 4. 3 pg/ml versus 12.6 pg/ml, P < 0.05; CA 6.5 pg/ml versus 60.3 pg/ml, P < 0.001). Consequently the ratio of IL-5 to IFN-gamma production was high not only in patients with BA but also in those with AD. These findings suggest that there are some differences in the regulation of in vivo cytokine production between patients with AD and those with BA, although a Th2-dominant profile is common to both.

Cellular sources of enhanced brain-derived neurotrophic factor production in a mouse model of allergic inflammation

The aim of this study was to investigate production and cellular sources of brain-derived neurotrophic factor (BDNF) production in allergic asthma. For this purpose a mouse model of chronic and severe ovalbumin (OVA)-induced airway inflammation was developed. Allergen-exposed mice developed elevated immunoglobulin E titers; airway inflammation with influx of lymphocytes, monocytes, and eosinophils; and airway hyperresponsiveness. In addition to an influx of inflammatory cells, interleukin (IL)-4 and IL-5 production were enhanced, macrophages showed morphologic signs of activation, and airway epithelium was thickened and displayed a goblet-cell hyperplasia with a marked mucus production. BDNF was detected using in situ hybridization and enzyme-linked immunosorbent assay. Constitutive expression of BDNF messenger RNA (mRNA) was observed in the respiratory epithelium of sensitized and nonsensitized mouse lungs. In addition, BDNF mRNA was detected in airway inflammatory infiltrations and bronchoalveolar lavage fluid (BALF) cells of OVA-sensitized and aerosol-challenged mice. Highest BDNF protein levels were detected in BALF after long-term allergen aerosol exposure. Analysis of BDNF production by isolated lymphocyte subsets revealed T but not B cells as a cellular source of BDNF. In addition, activated alveolar macrophages were identified as BDNF-positive cells. These data indicate that in allergic airway inflammation BDNF production is upregulated and immune cells serve as a source of BDNF.

Cytokine profiles of BAL T cells and T-cell clones obtained from human asthmatic airways after local allergen challenge

BACKGROUND

This study assessed the heterogeneity of cytokine expression in asthma before and after local allergen challenge.

METHODS

BAL T cells were obtained 10 min or 24 h after local endobronchial allergen challenge in atopic asthmatic subjects. T cells were cloned by direct limiting dilution. mRNA expression was assessed by RT-PCR, and cytokine protein production by ELISA.

RESULTS

Unstimulated baseline BAL T cells expressed mRNA for IFN-gamma, IL-13, and TNF-alpha. A minority of samples expressed IL-4 and IL-5, but no IL-3 mRNA was detected. PHA stimulation increased expression of IL-3, IL-4, and IL-5 mRNA in 4/6 samples. IL-13 and GM-CSF mRNA were found in BAL cells after allergen challenge, but expression of IFN-gamma was reduced. Both IL-4 and IL-3 were strongly upregulated after PHA stimulation, while the expression of TNF-alpha and IFN-gamma was reduced, compared to equivalent baseline samples. Seventeen panels of BAL T-cell clones were derived (average cloning efficiency 1/40 T cells). Seven panels survived to 8 weeks for analysis. Clones derived 4 h after saline challenge showed strong mRNA signals for IL-13, IL-4, and IFN-gamma, whereas clones derived 24 h after allergen challenge expressed IL-13, GM-CSF, IL-3, IL-4, and often IL-5 (i.e., closer to the Th2 profile). There was considerable heterogeneity in the patterns of cytokine mRNA and protein production by different clones.

CONCLUSIONS

T cells from asthmatic airways produce IL-13, IFN-gamma, and TNF-alpha, but after allergen challenge, type 2 cytokines are upregulated. mRNA and protein analysis provide complementary information on airways T-cell cytokine profiles.

Simultaneous Antagonism of Interleukin-5, Granulocyte-Macrophage Colony-Stimulating Factor, and Interleukin-3 Stimulation of Human Eosinophils by Targetting the Common Cytokine Binding Site of Their Receptors

Human interleukin-5 (IL-5), granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-3 are eosinophilopoietic cytokines implicated in allergy in general and in the inflammation of the airways specifically as seen in asthma. All 3 cytokines function through cell surface receptors that comprise a ligand-specific  chain and a shared subunit (βc). Although binding of IL-5, GM-CSF, and IL-3 to their respective receptor  chains is the first step in receptor activation, it is the recruitment of βc that allows high-affinity binding and signal transduction to proceed. Thus, βc is a valid yet untested target for antiasthma drugs with the added advantage of potentially allowing antagonism of all 3 eosinophil-acting cytokines with a single compound. We show here the first development of such an agent in the form of a monoclonal antibody (MoAb), BION-1, raised against the isolated membrane proximal domain of βc. BION-1 blocked eosinophil production, survival, and activation stimulated by IL-5 as well as by GM-CSF and IL-3. Studies of the mechanism of this antagonism showed that BION-1 prevented the high-affinity binding of125I–IL-5, 125I–GM-CSF, and125I–IL-3 to purified human eosinophils and that it bound to the major cytokine binding site of βc. Interestingly, epitope analysis using several βc mutants showed that BION-1 interacted with residues different from those used by IL-5, GM-CSF, and IL-3. Furthermore, coimmunoprecipitation experiments showed that BION-1 prevented ligand-induced receptor dimerization and phosphorylation of βc, suggesting that ligand contact with βc is a prerequisite for recruitment of βc, receptor dimerization, and consequent activation. These results demonstrate the feasibility of simultaneously inhibiting IL-5, GM-CSF, and IL-3 function with a single agent and that BION-1 represents a new tool and lead compound with which to identify and generate further agents for the treatment of eosinophil-dependent diseases such as asthma.

Simultaneous Antagonism of Interleukin-5, Granulocyte-Macrophage Colony-Stimulating Factor, and Interleukin-3 Stimulation of Human Eosinophils by Targetting the Common Cytokine Binding Site of Their Receptors

Human interleukin-5 (IL-5), granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-3 are eosinophilopoietic cytokines implicated in allergy in general and in the inflammation of the airways specifically as seen in asthma. All 3 cytokines function through cell surface receptors that comprise a ligand-specific  chain and a shared subunit (βc). Although binding of IL-5, GM-CSF, and IL-3 to their respective receptor  chains is the first step in receptor activation, it is the recruitment of βc that allows high-affinity binding and signal transduction to proceed. Thus, βc is a valid yet untested target for antiasthma drugs with the added advantage of potentially allowing antagonism of all 3 eosinophil-acting cytokines with a single compound. We show here the first development of such an agent in the form of a monoclonal antibody (MoAb), BION-1, raised against the isolated membrane proximal domain of βc. BION-1 blocked eosinophil production, survival, and activation stimulated by IL-5 as well as by GM-CSF and IL-3. Studies of the mechanism of this antagonism showed that BION-1 prevented the high-affinity binding of125I–IL-5, 125I–GM-CSF, and125I–IL-3 to purified human eosinophils and that it bound to the major cytokine binding site of βc. Interestingly, epitope analysis using several βc mutants showed that BION-1 interacted with residues different from those used by IL-5, GM-CSF, and IL-3. Furthermore, coimmunoprecipitation experiments showed that BION-1 prevented ligand-induced receptor dimerization and phosphorylation of βc, suggesting that ligand contact with βc is a prerequisite for recruitment of βc, receptor dimerization, and consequent activation. These results demonstrate the feasibility of simultaneously inhibiting IL-5, GM-CSF, and IL-3 function with a single agent and that BION-1 represents a new tool and lead compound with which to identify and generate further agents for the treatment of eosinophil-dependent diseases such as asthma.

Perimenstrual alterations in type-1/type-2 cytokine balance of normal women

BACKGROUND

Perturbations of the type-1/type-2 cytokine balance play a role in the pathogenesis of many diseases. Several immune-based diseases, such as asthma, have significant clinical exacerbations during specific intervals of the menstrual cycle and are associated with oral contraceptive pills (OCRs). The mechanism for these changes is not known, but may involve alterations in the type-1/type-2 cytokine balance.

OBJECTIVE

To determine if the type-1/type-2 cytokine balance in healthy women changes during a regular menstrual cycle.

METHODS

Peripheral blood mononuclear cells from 14 healthy women (seven taking monophasic OCPs) obtained during the perimenstrual interval (3 days prior to 4 days after the onset of menses) and the mid-cycle interval (days 13 to 16) were stimulated with PHA. Supernatants were analyzed for type-1 (IFN-gamma) and type-2 (IL-10) cytokines.

RESULTS

During the perimenstrual interval PBMC produced less IFN-gamma and more IL-10, resulting in a decreased IFN-gamma: IL-10 ratio compared with the mid-cycle interval. The perimenstrual decrease in the IFN-gamma: IL-10 ratio was observed in women not taking OCP, but not in women taking OCP. Furthermore, the OCP group had a lower mid-cycle IFN-gamma: IL-10 ratio compared with the control group. Finally, subjects reported increased levels of distress during the perimenstrual interval compared with the mid-cycle interval.

CONCLUSIONS

These data suggest that healthy women have a perimenstrual shift in the type-1/type-2 cytokine balance toward a type-2 response that is blunted in women taking OCP.

Specific inhibition of TH2-type cytokine production from human peripheral T cells by terfenadine in vitro

BACKGROUND

Cytokine imbalance is thought to be one of the causes for allergic diseases. The effect of anti-allergic drugs on cytokine production from T cells should be examined in a convenient way.

OBJECTIVES

To study the in vitro effect of terfenadine, a prototype non-sedating H1 receptor antagonist, on cytokine production from activated T cells.

METHODS

T cells were cultured in the presence of terfenadine on anti-CD3 mAb and anti-CD26 mAb-coated wells, anti-CD3 mAb and anti-CD28 mAb-coated wells, and anti-CD3 mAb wells with PMA. T-cell proliferation, along with the concentrations of interleukin (IL) -2, interferon (IFN) -gamma, IL-4, and IL-5 were measured.

RESULTS

Terfenadine inhibited T-cell proliferation and IL-4 and IL-5 production under each costimulatory condition tested, whereas it had no effect on IL-2 and IFN-gamma production.

CONCLUSIONS

These results indicate that terfenadine has a specific inhibitory effect on TH2-type cytokine production induced by several ways of costimulatory activation.