Asthma and inflammation

The Effects of Long-Term Administration of Sodium Nedocromil on Bronchial Hypereactivity

The effect of long-term treatment with sodium nedocromil on airway hypereactivity was investigated in two groups of 20 patients each. Group I patients presented with allergic asthma while Group II patients presented with intrinsic asthma. For each subject of the two groups, the base FEV1 was measured and nebulized methacholine was administrated in consecutively higher concentrations until a decrease in FEV1 of >20 % was observed. Following measurement, all patients included in the study were treated with 12 mg of sodium nedocromil per day for 12 months. At the end of the treatment, bronchial hyperreactivity was evaluated for a second time by administering the same dosage of methacholine that originally produced a decline in FEV1 of >20 %. In Group I patients (allergic asthma) mean FEV1 was 3126 ml, before challenge, while after methacholine challenge FEV1 was 2400ml. Following 1-year of sodium nedocromil administration the FEV1 was 2601ml (P<0.05). Before treatment, the mean fall in FEV1, following methacholine challenge, was 23.67% while following a 1-year-long sodium nedocromil administration this value reduced to 15.70% (P<0.05). Correspondingly, PC20 was 5.59 while after sodium nedocromil administration it increased to 11.66 (P<0.05). In Group II patients (intrinsic asthma) mean FEV1 was 2750 ml, before challenge, while after methacholine challenge FEV1 was 2066ml. Following 1-year of sodium nedocromil administration the FEV1 was 2223ml (P<0.05). Before treatment, the mean fall in FEV1, following methacholine challenge, was 27.65 % while following a 1-year-long sodium nedocromil administration this value reduced to 21.92 % (P<0.05). Correspondingly, PC20 was 5.91 while after sodium nedocromil administration it increased to 6.19 (P<0.05). The results suggest a positive effect of long-term sodium nedocromil administration in bronchial hyperreactivity for both groups of patients.

Matrix metalloproteinase inhibitor regulates inflammatory cell migration by reducing ICAM-1 and VCAM-1 expression in a murine model of toluene diisocyanate-induced asthma

BACKGROUND

Matrix metalloproteinase-9 (MMP-9) has been reported to play a crucial role in the transmigration of neutrophils, lymphocytes, and eosinophils. Neutrophils, eosinophils, and lymphocytes migrate from the blood to the lungs in response to inflammatory mediators produced in the airways and are subsequently released into the circulation. This traffic is mediated by adhesion molecules. However, little is known about the migration of inflammatory cells through the endothelial and epithelial basement membranes in toluene diisocyanate (TDI)-induced asthma.

OBJECTIVES

An aim of this study was to evaluate the effect of MMP inhibitors on the expression of ICAM-1 and VCAM-1 in the migration of inflammatory cells in a murine model of TDI-induced asthma.

METHODS

We used a murine model to investigate TDI-induced asthma to examine the possible involvement of ICAM-1 and VCAM-1 in the pathogenesis of that disease and the effect of MMP inhibitors on the expression of ICAM-1 and VCAM-1.

RESULTS

In mice, the following typical pathophysiologic features develop in the lungs: increased numbers of inflammatory cells and increased expression of MMP-9, ICAM-1, and VCAM-1 mRNA and protein. Administration of MMP inhibitors reduced the increased numbers of inflammatory cells and the increased expression of ICAM-1 and VCAM-1 mRNA expression and protein. In addition, MMP inhibitors significantly abrogated the increased expression of IL-1beta, IL-4, and TNF-alpha mRNA in lung tissues and levels of IL-1beta, IL-4, and TNF-alpha in bronchoalveolar lavage fluids after TDI inhalation.

CONCLUSIONS

These results suggest that MMP inhibitors regulate inflammatory cell migration by reducing ICAM-1 and VCAM-1 expression and possibly also by suppressing IL-1beta, IL-4, and TNF-alpha expression.

Immunohistochemical classification of the localization of laminin in the thickened bronchial epithelial basement membrane of deceased bronchial asthma patients

To ascertain histological changes in the basal lamina of the bronchial epithelial basement membrane in patients with severe bronchial asthma, an immunohistochemical study was conducted in 43 patients who died of bronchial asthma. Antibodies against laminin, a component of the lamina lucida, were utilized. The results revealed various patterns for immunoreactivity to laminin in the thickened basement membrane layer. We were able to classify these reactivities into four patterns. In Pattern A, laminin reactions branched vertically in relation to the thickened basement membrane layer. In Pattern B, laminin reactions formed lines along the lower margin of the thickened basement membrane layer. In Pattern C, laminin reactions formed lines along the upper margin of the thickened basement membrane layer. Finally, in Pattern D, no laminin reactions were observed. In addition, relationships between immunohistological characteristics of laminin and findings such as epithelial cell shedding, basal cell proliferation and basement membrane layer thickening were investigated. In many Pattern A patients, epithelial cell shedding was observed, but goblet cell hyperplasia and basal cell proliferation were barely detectable. Conversely, in numerous Pattern D patients, epithelial cell shedding was barely seen, but goblet cell hyperplasia and basal cell proliferation were marked. Hence, Patterns A and D were on opposite ends of the spectrum of morphological characteristics associated with severe bronchial asthma. In Patterns B and C, laminin reactions formed lines along the lower and upper margin of the thickened basement membrane layer, respectively. However, no marked differences existed in epithelial cell shedding and basement membrane layer thickening. The present study is thus the first to clarify that laminin reactions in the thickened basement membrane layer vary, and this feature is unique to the bronchi of patients with severe bronchial asthma.

Mast cells play a partial role in allergen-induced subepithelial fibrosis in a murine model of allergic asthma

BACKGROUND

Role of mast cells in the development of allergen-induced airway remodelling has not been fully investigated in vivo.

OBJECTIVE

To clarify the possible role of mast cells in the development of allergen-induced airway remodelling, we compared their responses of genetically mast cell-deficient mice, WBB6F1-W/Wv (c-kit mutant) and Sl/Sld (c-kit ligand mutant) mice with those of congenic normal mice in a murine model of allergic asthma.

METHODS

Mice were sensitized to ovalbumin (OA) with alum, and exposed daily for 3 weeks to aerosolized OA. Twenty-four hours after the last inhalation, bronchial responsiveness to acetylcholine (Ach) was measured, and bronchoalveolar lavage (BAL), and biochemical and histological examinations were performed.

RESULTS

In both sensitized mast cell-deficient mice, the degree of bronchial hyper-responsiveness to Ach, the number of inflammatory cells and the level of transforming growth factor-beta1 in BAL fluid, IgE response and goblet cell hyperplasia in the epithelium after repeated allergen provocation were not significantly different from those of congenic mice. In contrast, subepithelial fibrosis, evaluated in the fibrotic area around the airways, observed in congenic mice after repeated allergen challenge was partially attenuated in both mast cell-deficient mice. In addition, the amount of hydroxyproline in the lung of mast cell-deficient mice was significantly lower than that of congenic mice. Furthermore, the decreased fibrotic area and amount of hydroxyproline in W/Wv mice was completely recovered by reconstitution of tissue mast cells with bone marrow-derived mast cells of congenic mice.

CONCLUSION

These findings suggest that mast cells play a partial role in the development of allergen-induced subepithelial fibrosis, although airway inflammation, epithelial remodelling and BHR caused by repeated allergen challenge are independent of mast cells, at least in this model.

Enhancement of gelatinase activity during development of subepithelial fibrosis in a murine model of asthma

BACKGROUND

Chronic asthma is characterized by inflammatory cell infiltration and tissue remodelling leading to subepithelial fibrosis. Metalloproteinases (MMPs) are involved in degradation of extracellular matrix in most chronic inflammatory diseases.

OBJECTIVE

The aim of this study was to investigate the expression of MMPs in the development of inflammatory processes associated or not with the concomitant development of subepithelial fibrosis in an experimental model of asthma.

METHODS

Sensitized BP2 mice were challenged with ovalbumin (OA) every 2 weeks during 8 months. Several mice were removed once a month and bronchoalveolar lavages (BAL) or lung biopsies were performed.

RESULTS

Lung sections stained with picrosirius and hydroxyproline measurements showed a significant collagen deposition after 16 weeks of OA challenge, demonstrating the development of subepithelial fibrosis. Pulmonary inflammation was present from the first OA challenge and was consistent throughout the 8 months of the study. Moreover, an up-regulation and activation of MMP-9 and, to a less extent, MMP-2 were observed in BAL fluid from challenged mice. The level of tissue inhibitor of metalloproteinases (TIMP)-1 increased after 12 weeks of OA challenge vs. control mice.

CONCLUSION

This study reveals that a decrease in the activation of the MMP-9 due to the increase in TIMP-1, could contribute to excessive collagen deposition following repeated antigen challenge in sensitized mice.

Involvement of PTEN in airway hyperresponsiveness and inflammation in bronchial asthma

Phosphatase and tensin homologue deleted on chromosome ten (PTEN) is part of a complex signaling system that affects a variety of important cell functions. PTEN blocks the action of PI3K by dephosphorylating the signaling lipid phosphatidylinositol 3,4,5-triphosphate. We have used a mouse model for asthma to determine the effect of PI3K inhibitors and PTEN on allergen-induced bronchial inflammation and airway hyperresponsiveness. PI3K activity increased significantly after allergen challenge. PTEN protein expression and PTEN activity were decreased in OVA-induced asthma. Immunoreactive PTEN localized in epithelial layers around the bronchioles in control mice. However, this immunoreactive PTEN dramatically disappeared in allergen-induced asthmatic lungs. The increased IL-4, IL-5, and eosinophil cationic protein levels in bronchoalveolar lavage fluids after OVA inhalation were significantly reduced by the intratracheal administration of PI3K inhibitors or adenoviruses carrying PTEN cDNA (AdPTEN). Intratracheal administration of PI3K inhibitors or AdPTEN remarkably reduced bronchial inflammation and airway hyperresponsiveness. These findings indicate that PTEN may play a pivotal role in the pathogenesis of the asthma phenotype.

Role of interleukin-12 in the regulation of CD4+ T cell apoptosis in a mouse model of asthma

Allergic asthma, a chronic inflammatory disease of the airways, is characterized by the presence of T helper 2 cells and eosinophils in sputum, bronchoalveolar lavage, and mucosal biopsy specimens. Although the T helper 1-promoting cytokine, interleukin-12, is capable of inhibiting the T helper 2-driven asthma symptoms and bronchial responsiveness, the specific mechanisms underlying these interleukin-12 actions are unclear. The anti-allergic response to interleukin-12 is only partially dependent on interferon-gamma, which induces apoptosis by enhancing expression of Fas antigen. We therefore investigated in vivo whether the anti-allergic action of interleukin-12 is mediated through induction of apoptosis. C57BL/6 mice immunized to ovalbumin by intraperitoneal injection were challenged three times with an ovalbumin aerosol every second day for 7 days. Recombinant interleukin-12 was administered intravenously after the final challenge. After the last ovalbumin challenge, mice were examined for effects of interleukin-12 on inflammatory cell infiltration and apoptosis in the lung as detected by terminal deoxynucleotidyl transferase-mediated deoxyribonucleoside triphosphate nick end-labelling. Administration of interleukin-12 reduced ovalbumin-induced pulmonary eosinophilia (P < 0.01) and CD4+ T cell infiltration (P < 0.01). Moreover, treatment with interleukin-12 shortly after ovalbumin inhalation resulted in both increased interferon-gamma production (P < 0.01) and enhanced apoptosis of CD4+ T cells in allergic airway infiltrates (P < 0.05). These results suggest that the beneficial effects of interleukin-12 in asthma may include enhancement of apoptosis of CD4+ T cells in airways.

The Effects of Long-Term Treatment by Immunotherapy and Fluticazone on Broncial Hyperreactivity

Thirty subjects (20 female and 10 male), all allergic to the mites D. Pteronyssinus and D. Farinae, participated in the present study which covered a period of four years. The subjects were randomly divided in two groups. Group I included 10 female and 5 male subjects, with an average age of 25.8 (+/− 3.5) years who received immunotherapy only. Group II had an average age of 31.5 (+/− 4) years and they received immunotherapy along with fluticazone propionate (1000mcg/day). The protocol for immunotherapy was the same for both groups. The basis FEV1 was determined for each subject of both Groups I and II and afterwards they were subjected to provocation tests of nebulized methacholine solution administered in consecutively larger concentrations until a drop in FEV1 >20 % (PC20), was observed. Three years later, when their therapy was completed, all subjects were subjected to the same provocation test and a significant reduction in bronchial hyperactivity was documented for both groups. In particular, for Group I, the percentage of change in FEV1 values was 27.25 +/- 5.23 % and PC20 5.11 +/− 2.64 mg/ml before immunotherapy, while after immunotherapy the same indicators were 22.22 +/- 7.08 % (P<0.05) and 6.85 +/− 4.03 mg/ml, (P<0.05) respectively. For Group II, the percentage of change in FEV1 values was 26.28 +/− 2.5 % and PC20 5.42 +/− 2.5 mg/ml before immunotherapy, while after immunotherapy the same indicators were 12.27 +/- 2.49 % (P<0.01)and 11.64 +/− 5.14 mg/ml, P<0.01 respectively. It is concluded that although significant reduction in hyperreactivity can be achieved through immunotherapy, the combination of immunotherapy with daily fluticazone propionate administration shows the most promising results.

In allergic asthma experimental exposure to allergens is associated with depletion of blood eosinophils overexpressing LFA-1

BACKGROUND

In atopic individuals, exposure to allergens is followed by recruitment of blood eosinophils in the target tissue. We investigated whether allergen inhalation challenge could result in depletion of blood eosinophils overexpressing adhesion molecules involved in eosinophil migration.

METHODS

Blood eosinophils were isolated from seven atopic asthmatic patients and seven control subjects and the "at baseline" expression of lymphocyte function-associated antigen-1 (LFA-1), macrophage antigen-1 (Mac-1) and very late antigen-4 (VLA-4) was assessed by monoclonal antibody staining and flow cytometry analysis. Asthmatic patients underwent allergen challenge and the expression of LFA-1, Mac-1 and VLA-4 by blood eosinophils was again evaluated 3 h and 24 h after allergen challenge.

RESULTS

As compared to controls, eosinophils from atopics showed at baseline enhanced LFA-1 expression (P=0.0012), but similar Mac-1 or VLA-4 expression (P > 0.1, each comparison). In atopics, the percentage and absolute number of blood eosinophils were significantly decreased 3 h after allergen challenge (P=0.001 and P=0.022, respectively) but returned to similar values to prechallenge values after an additional 21 h (P > 0.1). Allergen challenge was also followed by a significant decrease in LFA-1 expression by eosinophils, at 3 h (P=0.002) and at 24 h (P=0.038), while no changes in Mac-1 and VLA-4 were observed. A significant correlation between postchallenge decrease in LFA-1 expression and in blood eosinophilia, both expressed as percentage (r=0.88; P < 0.01) or absolute number (r=0.87; P < 0.01) was demonstrated at 3 h (r=0.88; P < 0.01) but not at 24 h (r=0.64, P > 0.05 and r=0.11; P > 0.05, respectively).

CONCLUSION

In allergic asthma, an early recruitment of blood eosinophils overexpressing LFA-1 occurs in the first hours after allergen challenge.

The involvement of matrix metalloproteinases in basement membrane injury in a murine model of acute allergic airway inflammation

BACKGROUND

Airway remodelling in asthma such as subepithelial fibrosis is thought to be the repair process that follows the continuing injury as of chronic airway inflammation. However, how acute allergic inflammation causes tissue injury in the epithelial basement membrane in asthmatic airways remains unclear. Matrix metalloproteinases (MMPs) capable of degrading almost all of the extracellular matrix components have been demonstrated to be involved in cell migration through the basement membrane in vivo and in vitro.

OBJECTIVE

We investigated the alterations of matrix construction and the role of MMPs in matrix degradation in the subepithelium during acute allergic airway inflammation.

METHODS

Airway inflammation, the ultrastructure of the subepithelium and injury of types III and IV collagen in tracheal tissues from ovalbumin (OVA)-sensitized mice after OVA inhalation with or without the administration of tissue inhibitor of metalloproteinase-2 (TIMP-2) and dexamethasone were evaluated by cell counting in bronchoalveolar lavage (BAL) fluids, electron microscopy and immunohistochemistry, respectively.

RESULTS

The disruption of the lamina densa and matrix construction and the decrease of the immunoreactivity for type IV collagen in subepithelium were observed in association with the accumulation of inflammatory cells in airways 3 days after OVA inhalation. This disorganization of the matrix components in the subepithelium, as well the cellular accumulation, was abolished by the administration of TIMP-2 and dexamethasone. The immunoreactivity for type IV collagen in the subepithelium in OVA-inhaled mice returned to the level of that in saline-inhaled mice 10 days after inhalation in association with a decrease of the cell numbers in the BAL fluid. The immunoreactivity for type III collagen was changed neither 3 nor 10 days after OVA inhalation.

CONCLUSION

These results suggest that epithelial basement membrane gets injured by, at least in part, MMPs as a consequence of cell transmigration through the membrane during acute allergic airway inflammation.

Influence of different dosage schedules of inhaled fluticasone propionate on peripheral blood cytokine concentrations in childhood asthma

BACKGROUND

Asthma is characterized by eosinophilic airways inflammation with elevated levels of IL-4, IL-5 and sICAM-1, and reduced levels of IL-10 and IFN-gamma. Inhaled corticosteroids powerfully reduce airways inflammation.

OBJECTIVE

To investigate if eosinophil counts, serum eosinophilic cationic protein (ECP) and sICAM-1 levels, as well as serum and production of cytokines (IL-4, IL-5, IL-10, IFN-gamma) by peripheral blood monocytes (PBMCs) are useful markers to monitor therapy with inhaled fluticasone propionate (FP) in asthmatic children.

METHODS

In a double-blind, 1-year study, 55 asthmatic children (aged 6-10 years) stopped inhaled corticosteroids for a mean period of 24 days and were randomized to receive either FP 200 microg/day (constant dose group), or a starting dose of FP 1000 microg/day with two monthly reductions to 500, 200 and 100 microg/day (stepdown group). Hyper-responsiveness, symptom scores and blood sampling were performed at 2-month intervals.

RESULTS

Symptoms and hyper-responsiveness improved significantly in both treatment groups after reintroduction of FP. Eosinophil counts decreased significantly more during the first 2 months of FP in the stepdown group than in the constant dose group (P = 0.03). We found a trend towards a dose-dependent response in changes of eosinophil counts and serum ECP levels during treatment. Serum IL-4 and IL-5 levels were undetectable in the majority of children. No significant effect of the dose of FP on the release of IL-4, IL-5, IL-10 or IFN-gamma by Con A stimulated PBMCs was found. sICAM-1 levels did not significantly differ at any time point between the two groups.

CONCLUSION

Serum ECP as well as peripheral blood eosinophils, cytokine production by PBMCs and sICAM-1 levels are insensitive markers in titrating and monitoring therapy with inhaled corticosteroids over a wide dose range in childhood asthma.

Is there scientific evidence that suppression of acute diseases in childhood induce chronic diseases in the future?

Seeking to understand the individual in his symptomatic totality has been an aim of homeopathy since its beginning. Throughout its history, homeopaths have been concerned that inadequate treatment of acute diseases in childhood may lead to future chronic diseases. Hahnemann cautioned that by treating acute diseases with allopathic medicine, with strong doses of drugs, or suppressing local symptoms of those diseases, would increase the risk of future chronic diseases. Burnett proposed the theory of vaccinosis and warned of chronic manifestations subsequent to smallpox vaccination. French homeopaths, seeking the physiopathological origin of chronic diseases, correlated it to the abnormal reaction of the reticuloendothelial system (RES). Through the study of experimental pathology, Maffei attributed symptomatic manifestations to the imbalance between the immunological phenomena of allergy and immunity. He termed the sensitizing and pathogenic effects of medications and vaccines, 'metallergy' and 'parallergy', respectively. The hygiene hypothesis is based on evidence that the imbalance of immunological response in childhood, specifically among the Th1 and Th2 lymphocyte subpopulations, is responsible for the development of some allergic and chronic diseases in the future. The deranging factor for the predisposition to future allergic response (Th2) is the obstruction of natural manifestations of infectious diseases (Th1 response) in young children. Homeopathic treatment aims to equilibrate vital reaction, corresponding to an integrative physiological response, it may regulate Th1/Th2 imbalance. However, clinical trials to support this hypothesis are lacking.

p38 mitogen-activated protein kinase and c-Jun-NH2-terminal kinase regulate interleukin-8 and RANTES production in hyperosmolarity stimulated human bronchial epithelial cells

OBJECTIVE

We have previously shown that p38 mitogen-activated protein kinase (MAPK) regulates, at least in part, hyperosmolarity induced interleukin (IL)-8 expression in human bronchial epithelial cells (BEC). In the previous study, hyperosmolarity also activated c-Jun-NH2-terminal kinase (JNK); however, the role of the JNK signalling pathway has not been determined. In the present study, we examined the role of the JNK signalling pathway in hyperosmolarity induced IL-8 and RANTES production by BEC using the novel inhibitor of the JNK signalling pathway CEP 11004 in order to clarify these issues.

METHODS

Bronchial epithelial cells that had been pre-incubated with SB 203580, CEP 11004 or a combination of these were exposed to a hyperosmolar medium and then the p38 MAPK and JNK phosphorylation activity in these cells and IL-8 and RANTES concentrations in the culture supernatants were determined.

RESULTS

The results showed that: (i) hyperosmolarity induced the threonine and tyrosine phosphorylation of p38 MAPK and JNK; (ii) SB 203580, as the specific inhibitor of p38 MAPK activity, and CEP 11004 attenuated hyperosmolarity induced p38 MAPK and JNK activity, respectively; (iii) SB 203580 and CEP 11004, but not PD 98059, partially attenuated IL-8 and RANTES production; and (iv) a combination of SB 203580 and CEP 11004 attenuated IL-8 and RANTES production in an additive fashion.

CONCLUSION

These results indicate that p38 MAPK and the JNK pathway regulate hyperosmolarity induced IL-8 and RANTES production by BEC.

Key role for mast cells in nonatopic asthma

The mechanisms involved in nonatopic asthma are poorly defined. In particular, the importance of mast cells in the development of nonatopic asthma is not clear. In the mouse, pulmonary hypersensitivity reactions induced by skin sensitization with the low-m.w. compound dinitrofluorobenzene (DNFB) followed by an intra-airway application of the hapten have been featured as a model for nonatopic asthma. In present study, we used this model to examine the role of mast cells in the pathogenesis of nonatopic asthma. First, the effect of DNFB sensitization and intra-airway challenge with dinitrobenzene sulfonic acid (DNS) on mast cell activation was monitored during the early phase of the response in BALB/c mice. Second, mast cell-deficient W/W(v) and Sl/Sl(d) mice and their respective normal (+/+) littermate mice and mast cell-reconstituted W/W(v) mice (bone marrow-derived mast cells-->W/W(v)) were used. Early phase mast cell activation was found, which was maximal 30 min after DNS challenge in DNFB-sensitized BALB/c, +/+ mice but not in mast cell-deficient mice. An acute bronchoconstriction and increase in vascular permeability accompanied the early phase mast cell activation. BALB/c, +/+ and bone marrow-derived mast cell-->W/W(v) mice sensitized with DNFB and DNS-challenged exhibited tracheal hyperreactivity 24 and 48 h after the challenge when compared with vehicle-treated mice. Mucosal exudation and infiltration of neutrophils in bronchoalveolar lavage fluid associated the late phase response. Both mast cell-deficient strains failed to show any features of this hypersensitivity response. Our findings show that mast cells play a key role in the regulation of pulmonary hypersensitivity responses in this murine model for nonatopic asthma.

Anti-interleukin-9 antibody treatment inhibits airway inflammation and hyperreactivity in mouse asthma model

Numerous in vitro and in vivo studies in both animals and patients with asthma have shown that interleukin (IL)-9 is an important inflammatory mediator in asthma. To examine the effects of IL-9 antagonism on airway inflammation, ovalbumin-sensitized BALB/c mice were intravenously given anti-IL-9 antibody or an isotype-matched control antibody 30 minutes before challenge with aerosolized ovalbumin. Airway response to methacholine was measured, and samples of bronchoalveolar lavage fluid (BALF) were obtained 24 hours after the last antigen challenge. Lung tissue was harvested and examined histopathologically. After ovalbumin challenge, there were significant increases in airway hyperreactivity, the numbers of inflammatory cells in lung, and IL-4, IL-5, and IL-13 production in BALF. Treatment with anti-IL-9 antibody significantly prevented airway hyperreactivity in response to methacholine inhalation. Blockade of IL-9 reduced the numbers of eosinophils (0.3 +/- 0.1 x 10(5) and 23.6 +/- 0.5 x 10(5)/ml, anti-IL-9 antibody/control immunoglobulin G) and lymphocytes (0.2 +/- 0.2 x 10(5) and 0.8 +/- 0.1 x 10(5)/ml) in BALF. Anti-IL-9 antibody treatment also reduced the concentrations of IL-4 (from 70.6 +/- 4.6 to 30.8 +/- 5.2 pg/ml), IL-5 (from 106.4 +/- 12 to 54.4 +/- 6.6 pg/ml), and IL-13 (from 44.2 +/- 7.6 to 30.1 +/- 5.5 pg/ml) in BALF. Macrophage-derived cytokine expression in the airways was also decreased by IL-9 blockade. Taken together, our findings emphasize the importance of IL-9 in the pathogenesis of asthma and suggest that blockade of IL-9 may be a new therapeutic strategy for bronchial asthma.

Cellular adhesion is required for effector functions of human eosinophils via G-protein coupled receptors

BACKGROUND

Eosinophils play an important role in the pathogenesis of allergic diseases. Chemoattractants, including platelet-activating factor (PAF) and complement component 5a (C5a), induce eosinophil infiltration and promote eosinophil effector functions.

OBJECTIVE

To compare eosinophil degranulation and superoxide anion (O2-) generation induced by various chemoattractants, and to elucidate the role of cellular adhesion on these effector functions.

METHODS

Human eosinophils were stimulated with PAF, C5a, eotaxin, or leukotriene B4 (LTB4). O2- generation was assayed by a chemiluminescence method using a Cypridina luciferin analog as the amplifier. Degranulation and adhesion were measured by quantitating eosinophil protein X by radioimmunoassay. Expression of CD11b on eosinophils was measured by flow cytometry.

RESULTS

PAF and C5a induced significant degranulation and O2- generation from eosinophils. In contrast, the potency of eotaxin or LTB4 for these functions was much less. PAF and C5a also significantly enhanced eosinophil adhesion, whereas eotaxin and LTB4 did not. CD11b expression on eosinophils was enhanced by all four stimulants, and the order of potency to induce CD11b expression was C5a > PAF > eotaxin > LTB4.

CONCLUSIONS

The potency of PAF and C5a for inducing effector function in eosinophils was greater than that of eotaxin or LTB4. The magnitude of the effector function was consistent with the degree of eosinophil adherence induced by each stimulant. These results suggest that effector functions of eosinophils which are mediated through G-protein coupled receptors are dependent on cellular adhesion.

Asthma attack severity and urinary concentration of eosinophil X protein in children

OBJECTIVE

Determination of the urinary concentration of eosinophil protein X (U-EPX) may objectively predict the severity and activity of asthma in children.

METHODS

Concentrations of U-EPX in 80 non- atopic asthmatic children were compared with those in 25 healthy control children. The patients were studied during attacks and two weeks later. The severity of asthma attacks was determined according to a pre-existing score. U-EPX was measured by the specific radioimmunoassay technique (Pharmacia, Uppsala, Sweden). This measurement was correlated with the clinical and radiological investigations as well as with other variables such as blood oxygen saturation, peak expiratory rate and eosinophil count.

RESULTS

U-EPX concentrations were significantly higher in all asthmatic children during attacks (139.6 11.7 microg/mmol of creatinine) than those in the control group (35.3 6.2 microg/mmol of creatinine) (p < 0.001). Two weeks after resolution of the exacerbation, U-EPX significantly decreased (66.5 9.3 microg/mmol of creatinine) (p < 0.001). U-EPX concentrations were highest in patients with severe attacks (191.5 11.3 microg/mmol of creatinine) (p < 0.001). No statistically significant differences were found between mild (88.2 7.2 microg/mmol of creatinine) and moderate attacks (119.6 8.5 microg/mmol of creatinine). At the two-week follow-up, U-EPX concentrations in patients with mild or moderate attacks was similar to those in controls but were persistently elevated in the subgroup with severe attacks (103.8 9.4 microg/mmol of creatinine) (p < 0.001). No significant correlation was found between U-EPX concentrations and blood oxygen saturation, peak expiratory rate or eosinophil count.

CONCLUSION

A statistically significant correlation was found between U-EPX concentrations and the severity of attacks in asthmatic children. This substance could be useful in quantifying bronchial inflammation. This result could further be used as a marker of severity of disease exacerbation and would not only facilitate early diagnosis and staging of inflammatory and allergic disorders but would also allow therapy and interventions to be monitored.

Proliferative effects of eosinophil lysates on cultured human airway smooth muscle cells

BACKGROUND

The hypertrophy/hyperplasia of airway smooth muscle (ASM) cells is one of the characteristic features of bronchial asthma. This structural change leads to the thickening of airway walls resulting in the amplification of airway narrowing. However, the pathogenesis of this structural change has not yet been determined. Eosinophils, which play a pathogenic role in asthma, have been demonstrated to have proliferative effects on fibroblasts and vascular smooth muscle cells.

OBJECTIVE

We attempted to investigate the potential of eosinophils to induce the proliferation of ASM cells.

METHODS

We examined the effect of lysates of eosinophils purified from peripheral blood of healthy donors on cultured human ASM cell proliferation.

RESULTS

Eosinophil lysates significantly induced ASM cell proliferation in time- and dose-dependent manners, reaching a maximum on day 6 at 50% of eosinophil lysates (6.0 +/- 0.7 x 104 [mean +/- SD] /well, n = 5 vs. 4.5 +/- 1.1 x 104/well, n = 5; P < 0.05). This proliferative activity was heat-sensitive and recovered in the soluble fraction of the eosinophil lysates. Furthermore, the molecular weight of the mitogenic activity in the soluble fraction was identified as lower than 10 kDa. The inhibitory activity to ASM cell proliferation was also found in the insoluble fraction of the lysates.

CONCLUSION

These results indicate that circulating eosinophils store mitogenic activity for ASM cells, suggesting that eosinophils might contribute to the development of the hyperplasia of ASM cells in asthmatics through the release of the stored mitogenic activity upon stimulation at the site of inflammation.

Inhaled corticosteroids and bone density of children with asthma

In this cross-sectional study, we aimed to compare anteroposterior (AP) spine and total body bone mineral density (BMD) measurements of children with asthma treated with long-term inhaled budesonide (n = 52, mean age 6.4+/-2.2yr, M/F = 22/30) (Group I) with those of asthmatic children who had never received treatment with inhaled corticosteroids (Group II) (n = 22, mean age 6.8+/-2.2, M/F = 10/12). Boys and girls were comparable for age, weight, height, cumulative corticosteroid (CS) dosage, duration of disease and inhaled corticosteroid (ICS) treatment within each group. The mean total accumulated dosage of budesonide for children in Group I was 154.0+/-135.3mg (mean daily dosage = 419+/-154 microg) and the mean treatment duration was 13.0+/-9.8 months. The two groups were comparable with respect to age, gender, weight, height, Tanner's stage and duration of disease. There was no significant difference between subjects in the two groups for total (p = 0.214) and (AP) spine BMD results (p = 0.661), respectively. Our results provide additional support for the safety of ICS therapy on bone density of asthmatic children.

Inhibitory effect of lidocaine on T cells from patients with allergic asthma

BACKGROUND

Nebulized lidocaine enables dosages of oral corticosteroids to be tapered in the treatment of severe asthma.

OBJECTIVE

We sought to investigate the effect of lidocaine on T cells from patients with allergic asthma.

METHODS

PBMCs and CD4(+) T cells were isolated from 6 patients with asthma and house dust mite allergy. PBMCs were cultured with lidocaine for up to 7 days and then stained with propidium iodide to evaluate the involvement of apoptosis. In addition, the viability of CD4(+) T cells when cultured with lidocaine was investigated. Effects of lidocaine on proliferative response, mRNA expression, and protein production of IL-5 and IFN-gamma by PBMCs were investigated after stimulation with Dermatophagoides farinae, purified protein derivative, and phorbol 12-myristate 13-acetate plus calcium ionophore. The effects of lidocaine on the proliferative response of steroid-insensitive PBMCs from 6 nonallergic donors induced by preculture with IL-2 and IL-4 were also investigated.

RESULTS

No significant increase in the staining of PBMCs with propidium iodide was observed in the presence of 100 micromol/L lidocaine. The viability of CD4(+) T cells was not significantly affected by culture with lidocaine at this concentration. However, lidocaine inhibited, in a dose-dependent manner, the proliferative response and mRNA expression and protein production of IL-5 and IFN-gamma of PBMCs stimulated with D farinae, purified protein derivatives, or phorbol 12-myristate 13-acetate plus calcium ionophore. Preincubation of PBMCs with IL-2 and IL-4 significantly decreased the inhibitory effects of both corticosteroids and lidocaine compared with that after preincubation with medium alone.

CONCLUSION

Lidocaine has immunoregulatory effects on T cells. Therefore, lidocaine might be studied as an anti-inflammatory agent in the treatment of severe steroid-dependent asthma.

The effect of anti-allergic mattress encasings on house dust mite-induced early- and late-airway reactions in asthmatic patients. A double-blind, placebo-controlled study

BACKGROUND

Anti-allergic mattress encasing may provide clinical benefit in asthmatic patients. However, the effect of mattress encasings on allergen-specific parameters, such as bronchial reactions to house dust mite (HDM) challenge, is not clear.

OBJECTIVE

To investigate the effect of anti-allergic mattress encasings on allergen sensitivity in patients with moderate to severe asthma.

METHODS

Twenty-seven patients with asthma and HDM allergy were studied in a double-blind, placebo-controlled study. Concentrations of Dermatophagoides pteronyssinus (Der p 1) were measured in mattress dust before and after 1 year of treatment; bronchial histamine challenge, bronchial challenge with HDM and intradermal skin challenges with HDM were performed. The number of eosinophils in peripheral blood was assessed.

RESULTS

In the active group, but not in the placebo group, there was a significant reduction in Der p 1 concentration in the dust collected from the mattresses after 1 year of treatment compared to before. There was a significant difference between the groups with respect to HDM-induced early-reaction (ER) in the airways and the number of blood eosinophils, which reflected an increase in ER and eosinophils in the placebo group without significant change in the active group. No significant improvement in PC20 histamine, late-reaction (LR) and skin tests was found in either groups.

CONCLUSION

Our data suggest that encasings protect against a further increase in allergen sensitivity in asthmatic patients, so their use should be recommended.

Influence of a macrolide antibiotic, roxithromycin, on mast cell growth and activation in vitro

BACKGROUND

Long-term administration of macrolide antibiotics is recognized to be able to favorably modify the clinical condition of inflammatory diseases, such as diffuse panbronchiolitis and cystic fibrosis. However, the precise mechanisms by which macrolide antibiotics could improve clinical conditions of the patients are not well understood.

AIM

The present study was designed to examine the influence of macrolide antibiotics on effector cell functions responsible for inflammation through the choice of roxithromycin (RXM) and mast cell.

METHODS

Mast cells were induced by long-term culture of splenocytes from BALB/c mice. RXM was added to the cultures at seeding and then every 4-5 days, when the culture medium was replaced with a fresh one. The influence of RXM on mast cell growth was evaluated by counting the number of cells grown on the 16th day. We also examined the influence of RXM on mast cell activation by examining histamine release and inflammatory cytokine secretion.

RESULTS AND CONCLUSION

RXM could not inhibit mast cell growth, even when splenocytes were exposed to 100 microg/ml of RXM throughout the entire culture periods. RXM also could not suppress histamine release from cultured mast cells in response to non-immunological and immunological stimulations. However, RXM could suppress inflammatory cytokine, interleukin-1beta, interleukin-6, granulocyte macrophage-colony stimulating factor and tumor necrosis factor-alpha, secretions induced by concanavalin A stimulation at a concentration of as little as 0.5 microg/ml. These results may suggest that RXM modulated the ability of mast cells to secrete inflammatory cytokines and results in improvement of clinical condition of chronic inflammatory diseases.

Effects of xiao-qing-long-tang (XQLT) on bronchoconstriction and airway eosinophil infiltration in ovalbumin-sensitized guinea pigs: in vivo and in vitro studies

BACKGROUND

Xiao-qing-long-tang (XQLT sho-seiru-to), a traditional Chinese medicine, has been used to treat patients with bronchial asthma in Oriental countries for several centuries. However, the therapeutic mechanisms of this Chinese medicine remain a matter of considerable debate. Therefore, a series of experiments using ovalbumin-sensitized guinea pigs was performed to elucidate the possible antiasthmatic effect of XQLT.

METHODS

The effect of XQLT on ovalbumin-induced airway inflammation in a guinea pig model of allergic asthma was examined, and early and late asthmatic responses were measured in terms of airway resistance and extent of eosinophil infiltration. Furthermore, the bronchorelaxing effect of XQLT was measured in isolated guinea pig trachea.

RESULTS

XQLT significantly inhibited the antigen-induced immediate asthmatic response (IAR) and late asthmatic response (LAR) in actively sensitized guinea pigs. Cumulative administration of XQLT caused concentration-dependent relaxation of the carbachol-precontracted guinea pig trachea. The bronchorelaxing effect of XQLT was reversed by ICI-118551, a selective beta2-adrenoceptor antagonist. Furthermore, examination of bronchoalveolar lavage fluid (BALF) revealed that XQLT significantly suppressed the increase in eosinophils (24 h after antigen challenge) in the airway. In addition, XQLT significantly attenuated the increase in eosinophils at 1, 6, 24, 48, and 72 h after antigen challenge when it was administered once daily from the day of sensitization to the day of challenge. Histopathologic examination results showed that XQLT suppressed eosinophil infiltration into lung tissue.

CONCLUSIONS

These results demonstrate that the antiasthmatic effects of XQLT appear to be partly mediated by stimulation of beta2-adrenoceptors, leading to bronchorelaxation, and that XQLT inhibits the infiltration of eosinophils into the airway. Thus, XQLT may be useful for the prevention or treatment of asthma.

Exhaled nitric oxide levels in non-allergic and allergic mono- or polysensitised children with asthma

BACKGROUND

Increased fractional exhaled NO concentrations (FENO) and blood/tissue eosinophilia are frequently reported in allergic children with mild asthma and are thought to reflect the intensity of the inflammation characterising the disease. The aim of this study was to investigate possible differences in FENO levels or in the intensity of the blood eosinophilia in allergic and non-allergic asthmatic children.

METHODS

112 children with stable, mild, intermittent asthma with a positive bronchial challenge to methacholine were consecutively enrolled in the study; 56 were skin prick test and RAST negative (non-sensitised) while 56 were sensitised to house dust mites (23 only to house dust mites (monosensitised) and 33 were sensitised to mites and at least another class of allergens (pollens, pet danders, or moulds)). Nineteen sex and age matched healthy children formed a control group.

RESULTS

Compared with non-allergic patients, allergic children had a significantly higher rate of blood eosinophilia (p=0.0001) with no differences between mono- and polysensitised individuals. Forced expiratory volume in 1 second (FEV(1)), forced vital capacity (FVC), forced expiratory flow at 25-75% of vital capacity (FEF(25-75%)), and the degree of bronchial reactivity to methacholine were similar in non-atopic and atopic children, with no differences between mono- and polysensitised individuals. FENO levels measured by chemiluminescence analyser were higher in asthmatic children (15.9 (14.3) ppb) than in the control group (7.6 (1.6) ppb, p=0.04) and higher in allergic patients (23.9 (2.1) ppb) than in non-allergic patients (7.9 (0.8) ppb, p=0.0001), but there were no differences between mono- and polysensitised individuals (p>0.1). Significant correlations between blood eosinophilia and FENO levels were seen only in allergic (r=0.35, p<0.01) and in polysensitised individuals (r=0.45, p<0.05).

CONCLUSIONS

In children with mild asthma, a similar degree of functional disease severity may be associated with a higher inflammatory component in allergic than in non-allergic subjects.

Effect of anti-mIL-9 antibody on the development of pulmonary inflammation and airway hyperresponsiveness in allergic mice

Interleukin (IL)-9 is a T-cell-derived cytokine with pleiotropic activities on T helper 2 cells, B cells, and mast cells. IL-9 may therefore play an important role in the development of allergic pulmonary inflammatory diseases. In this study, an antimouse IL-9 (anti-mIL-9) antibody (Ab) was evaluated against pulmonary eosinophilia, histopathologic changes in lung tissues, serum immunoglobulin (Ig) E levels, and airway hyperresponsiveness (AHR) to methacholine in mice sensitized and challenged with ovalbumin (OVA). Additionally, steady-state levels of IL-4, IL-5, IL-13, and interferon-gamma messenger RNA (mRNA) in the lungs were measured. The anti-mIL-9 Ab (200 microg/mouse, intraperitoneally) was given as either four doses during the sensitization period or as a single dose before OVA challenge. Sensitized mice challenged with OVA displayed marked pulmonary eosinophilia, epithelial damage, and goblet cell hyperplasia. OVA challenge also increased mRNA levels of IL-4, IL-5, and IL-13 in the lungs. AHR was also increased twofold in sensitized, challenged mice. Treatment of sensitized, challenged mice with four doses of anti-mIL-9 Ab significantly reduced pulmonary eosinophilia, serum IgE levels, goblet cell hyperplasia, airway epithelial damage, and AHR, but had no effect on IL-4, IL-5, and IL-13 mRNA levels in the lungs. A single dose of the antibody was ineffective on all measures. These results indicate that an antibody to mIL-9 inhibits the development of allergic pulmonary inflammation and AHR in mice.

Effect of wortmannin on human eosinophil responses in vitro and on bronchial inflammation and airway hyperresponsiveness in Guinea pigs in vivo

Many mediators activate eosinophils via transduction pathways involving the enzyme phosphatidylinositol 3-kinase. The initial investigation of wortmannin, a specific inhibitor of PI3-kinase, was of its effect on human and guinea pig eosinophil superoxide (O(2)(-)) release and degranulation in vitro. Subsequently, the effect on allergen- and Sephadex-induced bronchial inflammation and airway hyperresponsiveness (AHR) in vivo in guinea pigs was investigated. Wortmannin potently inhibited complement C5a-induced O(2)(-) generation and eosinophil peroxidase (EPO) release from human eosinophils, with 50% inhibition produced by a 1-10 nM concentration. Both aerosol allergen challenge of sensitized guinea pigs and intravenous injection of Sephadex beads in normal guinea pigs caused, in 24 h, significant eosinophilia and increased EPO activity in bronchoalveolar lavage fluid (BALF) and AHR to intravenous acetylcholine and histamine. In the allergic model, intranasal pretreatment with wortmannin had no effect on BALF eosinophilia, but dose dependently inhibited BALF EPO activity. At 1 mg/kg, the drug abolished the AHR to histamine, but not acetylcholine. In the Sephadex model, the drug significantly inhibited all three parameters (eosinophilia, increased EPO activity, and AHR to both spasmogens). These results show that wortmannin is a potent inhibitor of human eosinophil degranulation and that when administered intranasally can prevent AHR in allergen-challenged guinea pigs, probably by inhibiting eosinophil degranulation, but not their accumulation in BALF. This may be relevant to the possible clinical utility of wortmannin in conditions involving eosinophilic inflammation and AHR.

Seasonal differences of peak expiratory flow rate variability and mediators of allergic inflammation in non-atopic adolescents

Variations in peak expiratory flow (PEF) and serum eosinophil mediators were studied in healthy adolescents. Twenty-five boys and 31 girls, 11-16 years of age (mean age 14.3 years), were selected and investigated during the birch pollen season of 1995; 45 were also investigated during the autumn of the same year. The PEF was measured twice daily and eosinophil mediators in serum and in urine were measured by radioimmunoassay (RIA) once during the birch pollen season and once in autumn. The type values of the daily PEF variation, expressed in amplitude percentage mean, were 6.4 and 3.9%, mean values were 7.35 and 6.74%, and the 95th percentiles were 18 and 14%, during the birch pollen season and autumn, respectively. The 95th percentiles were 41 and 38 microg/l for serum eosinophil cationic protein (s-ECP), 74 and 62 microg/l for serum eosinophil protein X (s-EPX), 987 and 569 microg/l for serum myeloperoxidase (s-MPO), and 165 and 104 microg/mmol for urinary eosinophil protein X/urinary creatinine (u-EPX/u-creatinine), during the birch pollen season and autumn, respectively. The levels of the eosinophil mediators decreased significantly from May (n = 56) to November (n = 45), for s-ECP from a median value of 14 microg/l to 7 microg/l (p= 0.001), for s-EPX from a median value of 28 microg/l to 20 microg/l (p= 0.001), and for the neutrophil mediator, s-MPO, from a median value of 440 g/l to 292 g/l (p< 0.001). The PEF variability decreased significantly (p= 0.037), from spring (n = 55; median 8%, 95% confidence interval [CI] 7.8-10.19) to autumn (n = 44; median 6%, 95% CI 6.1-8.9). A significant correlation was found between the levels of s-ECP and s-EPX (rs = 0.7, p< 0.001), between s-ECP and s-MPO (rs = 0.6, p< 0.001), between s-EPX and s-MPO (rs = 0.4, p< 0.005), and between s-EPX and u-EPX/u-creatinine (rs = 0.6, p< 0.0001), in the birch pollen season (n = 56) and in the autumn (n = 45). There was a positive correlation found in PEF variability between the two seasons (n = 43; rs = 0.5, p= 0.0006). No other correlation was found between PEF variability and any other parameters. The difference in the levels of eosinophil mediators between seasons in non-atopic, healthy children is unexplained. Normal limits for mediators were higher and PEF variability was almost the same as has been reported in adults. When using normal values, seasonal influences should be considered.

Hyperalgesia and edema responses induced by rat peripheral blood mononuclear cells incubated with carrageenin

The aim of this study was to verify the role played by mononuclear cells in an acute (nonimmune) inflammatory reaction. Mononuclear cells purified from rat peripheral blood were incubated for 1, 2, or 24 h with 100 or 250 microg/ml carrageenin (Cg). The resultant donor supernatant was injected into recipient rats to test its ability to induce hyperalgesia (reduction in threshold for paw pressure) and edema (increase in paw volume). Mononuclear cell supernatants (MnS) induced a significant time- and dose-dependent hyperalgesia and edema in rat paws, which reached a maximal effect at 3 h, lasted for 6 h, and returned to basal levels at 24 h of injection. Prostaglandins and cytokines (interleukin 1, 2, 6, 8, and tumor necrosis factor alpha) accounted for the hyperalgesia induced by MnS, as it was reduced (40 to 90%) by synthesis inhibitors such as indomethacin, dexamethasone, rolipram, and cyclosporin added to the cultures at a microgram dose-range. Edema was dependent on serotonin release in rat paws. These results indicate that mononuclear cells may be important contributors to acute inflammatory reactions, especially under those conditions where pain is an important component.

Time-dependent changes in orally exhaled nitric oxide and pulmonary functions induced by inhaled corticosteroids in childhood asthma

Exhaled nitric oxide levels are elevated in asthmatic children and decrease after inhaled steroid treatment. We evaluated the time-dependent changes in fractional exhaled nitric oxide concentration (FENO) and pulmonary function parameters following inhaled steroid therapy. Thirty-nine steroid-naive atopic patients (age 11.92+/-0.48 years) with mild intermittent asthma and 22 age-matched healthy controls were enrolled in the study; pulmonary functions and FE(NO) levels were measured. Low doses of inhaled steroids were prescribed to all asthmatic patients who were reevaluated in a second visit (between 10 and 40 days after the beginning of the treatment). At the enrolment, asthmatic patients had similar forced expiratory volume in 1 sec (FEV1) and forced vital capacity (FVC) values (p > 0.05) but reduced forced expiratory flows at 25-75% of the vital capacity (FEF(25-75%)) values, as compared to controls (p < 0.05). In addition, FE(NO) levels were significantly higher in asthmatics with respect to control subjects (30.8+/-3.0 and 4.0+/-0.5 ppb, respectively; p < 0.01). All asthmatics had FE(NO) levels higher than 8.8 ppb (i.e., > 2 standard deviations of the mean in controls). After steroid treatment, patients showed significant improvement of FEV1, FVC, and FEF(25-75%) (p = 0.0001; each comparison) and a reduction of FE(NO) levels (p = 0.0001). A weak significant correlation was found between percent decrease in FE(NO) levels and percent increase in FEV1 (r = 0.33, p = 0.04) or in FEF(25-75%) (r = 0.4, p = 0.01) after treatment. When changes in FE(NO) levels and in pulmonary function parameters were corrected for days of treatment, significant correlations were still present between percent decrease in FE(NO) levels and percent increase in FEV1 (r = 0.57, p = 0.0004) or percent increase in FEF(25-75%) (r = 0.45, p = 0.006). Sixteen of the 39 asthmatic patients were evaluated on two occasions after the beginning of treatment, at days 10 and 40. The significant reduction in FE(NO) levels (p < 0.01) and the significant increase in FEV1 and FEF(25-75%) values observed (p < 0.05) after 10 days did not further improve at day 40. These data show that it is possible to demonstrate early effects of low-dose inhaled steroids in asthmatic children using objective measurements of airway caliber and inflammation.

The interaction of the polymorphisms in transporter of antigen peptides (TAP) and lymphotoxin alpha (LT-alpha) genes and atopic diseases in the Czech population

BACKGROUND

Transporter antigen peptide gene (TAP) products are involved in antigen processing. These genes, inducible by interferon gamma, as well as lymphotoxin alpha (LT-alpha), are located in the HLA region. Their involvement in immune response regulation makes them candidate atopy susceptibility genes.

OBJECTIVE

This study investigates a possible association between previously identified polymorphisms within the TAP-1 and LT-alpha genes and clinically manifested atopic diseases in the Czech population.

METHODS

Caucasian subjects of Czech nationality (n = 427) were included in our study. We examined 184 healthy controls and 243 patients with histories of atopic asthma, allergic rhinitis and atopic dermatitis or their combinations. We used the amplification refractory mutation system polymerase chain reaction to determine TAP-1 gene polymorphisms. LT-alpha genotypes were determined by PCR and restriction analysis by NcoI.

RESULTS

No significant differences were found in allele or genotype frequencies of the LT-alpha gene, as well as in polymorphisms for Val-->Ile at codon 333 and Gly-->Asp at codon 637 in the TAP-1 gene between controls and patients. However, analysis of the concurrence of the double genotypes of the TAP-1 polymorphism at codon 333 and the LT-alpha genes showed differences between controls and atopic patients (P < 0.02).

CONCLUSION

Several reports have indicated that different HLA products and genes may be risk factors for or protective factors against the development of atopy. We report no association between polymorphisms in the LT-alpha and TAP-1 genes alone and atopic diseases in the central Europe Caucasian (Czech) population, but there was an interesting interaction between the TAP333 and LT-alpha polymorphisms.

The role of leukotriene receptor antagonists in the treatment of chronic asthma in childhood

A considerable increase in the prevalence of childhood asthma over the last few decades has been mirrored by a dramatic increase in usage of anti-asthma drugs; however, there has been no reduction in the numbers of patients dying of asthma. Concern has been expressed about the development of tolerance with continuous use of inhaled beta-agonist bronchodilators and about the potential adverse systemic effects of high-dose inhaled corticosteroids in children. Moreover, patient compliance with inhaled therapy tends to be poor. The leukotriene receptor antagonists, including montelukast, pranlukast and zafirlukast, are orally administered agents with proven benefits in asthma. In a large, placebo-controlled pediatric trial, montelukast significantly (P < 0.02) reduced requirements for rescue beta-agonist bronchodilators, improved quality of life, reduced the circulating level of blood eosinophils and produced improvements in lung function. In adult studies, montelukast reduced sputum eosinophils and attenuated early and late phase allergen-induced reactions. Montelukast has also demonstrated protective effects against exercise-induced bronchospasm in both adults and children, and this protection was maintained during the trough period at the end of the once-daily administration interval (namely, 20-24 h post-dose). Several studies have demonstrated that the formation of cysteinyl leukotrienes in the airways of asthmatic patients is not suppressed by corticosteroids; thus, it is not surprising that montelukast demonstrates complementary effects when given with inhaled corticosteroids. Currently, the most compelling evidence from published trials suggests that leukotriene receptor antagonists can be used as add-on therapy to inhaled corticosteroids to allow tapering of corticosteroid dose and reduction in beta-agonist use. Recent clinical trial results suggest there may also be a role for these agents as first-line therapy in children with mild asthma.

A549 cells can express interleukin-16 and stimulate eosinophil chemotaxis

Alveolar epithelial cells produce many types of chemokines such as regulated on activation, normal T cells expressed and secreted (RANTES), eotaxin induced by interleukin (IL)-1 beta, or tumor necrosis factor (TNF)-alpha and may contribute to allergic disease by recruiting eosinophils. However, identification of the eosinophil chemotacic activity (ECA) release from A549 cells, an alveolar type II cell line, has not yet been completed. Recently, IL-16 was also reported to be a potent chemotactic stimulus for CD4(+) T lymphocytes and eosinophils in asthma and other pulmonary diseases. To test the possibility that alveolar epithelial cells produce IL-16, we analyzed RNA and culture supernatant from A549 cells by reverse transcription/ polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). The release of ECA from A549 cells was assessed using a blind-well chemotactic chamber. IL-16 release was increased in a concentration-dependent manner by stimulation with IL-1 beta or TNF-alpha. A549 cells also expressed IL-16 messenger RNA. The combination of IL-4 and IL-1 beta or TNF-alpha had an additive effect on IL-16 production. The release of ECA was induced by IL-1 beta or TNF-alpha in a dose-dependent manner. The combination of these cytokines had a greater effect than one alone. The blockade of eotaxin and IL-16 caused 70% inhibition of ECA, but anti-RANTES antibodies only caused 30% inhibition and anti-IL-8 antibodies failed to affect inhibition. These findings suggest a role for chemokines released by alveolar epithelial cells in the recruitment of eosinophils into the lung in pulmonary disorders such as asthma and interstitial lung diseases, and suggested that eotaxin and IL-16 are potent and effective eosinophil chemoattractants.

Understanding the pathogenesis of allergic asthma using mouse models

OBJECTIVE

This paper reviews the current views of the pathogenesis of airway eosinophilic inflammation and airway hyperresponsiveness (AHR) in allergic asthma based on mouse models of the disease. The reader will also encounter new treatment strategies that have arisen as this knowledge is applied in practice.

DATA SOURCES

MEDLINE searches were conducted with key words asthma, mouse model, and murine. Additional articles were identified from references in articles and book chapters.

STUDY SELECTION

Original research papers and review articles from peer-reviewed journals were chosen.

RESULTS

Although the mouse model does not replicate human asthma exactly, the lessons learned about the pathogenesis of allergic airway inflammation and AHR are generally applicable in humans. Type 2 T helper lymphocytes (Th2) orchestrate the inflammation and are crucial for the development of AHR. Cells and molecules involved in T cell activation (dendritic cells, T cell receptor, major histocompatibility complex molecule, and costimulatory molecules) are also vital. Besides these, no other cell or molecule could be shown to be indispensable for the establishment of the model under all experimental conditions. There are at least three pathways that lead to AHR. One is dependent on immunoglobulin E and mast cells, one on eosinophils and interleukin-5 (IL-5), and one on IL-13. Eosinophils are probably the most important effector cells of AHR. Radical methods to treat asthma have been tested in the animal model, including modifying the polarity of lymphocyte response and antagonizing IL-5.

CONCLUSIONS

AHR, the hallmark of asthma, is attributable to airway inflammation ultimately mediated by helper T cells via three pathways, at least. The mouse model is also a valuable testing ground for new therapies of asthma.

IL-13 induces airways hyperreactivity independently of the IL-4R alpha chain in the allergic lung

The potent spasmogenic properties of IL-13 have identified this molecule as a potential regulator of airways hyperreactivity (AHR) in asthma. Although IL-13 is thought to primarily signal through the IL-13Ralpha1-IL-4Ralpha complex, the cellular and molecular components employed by this cytokine to induce AHR in the allergic lung have not been identified. By transferring OVA-specific CD4(+) T cells that were wild type (IL-13(+/+) T cells) or deficient in IL-13 (IL-13(-/-) T cells) to nonsensitized mice that were then challenged with OVA aerosol, we show that T cell-derived IL-13 plays a key role in regulating AHR, mucus hypersecretion, eotaxin production, and eosinophilia in the allergic lung. Moreover, IL-13(+/+) T cells induce these features (except mucus production) of allergic disease independently of the IL-4Ralpha chain. By contrast, IL-13(+/+) T cells did not induce disease in STAT6-deficient mice. This shows that IL-13 employs a novel component of the IL-13 receptor signaling system that involves STAT6, independently of the IL-4Ralpha chain, to modulate pathogenesis. We show that this novel pathway for IL-13 signaling is dependent on T cell activation in the lung and is critically linked to downstream effector pathways regulated by eotaxin and STAT6.

Nitrobenzene compounds inhibit expression of VCAM-1

A series of nitrobenzene compounds has been discovered as potent inhibitors of VCAM-1 expression and, therefore, potential drug candidates for autoimmune and allergic inflammatory diseases. Structure-activity relationship (SAR) studies showed that a nitro group and two other electron-withdrawing groups are essential for these compounds to be potent inhibitors of VCAM-1 expression.

Functional expression of IL-12 receptor by human eosinophils: IL-12 promotes eosinophil apoptosis

In murine models of allergic inflammation, IL-12 has been shown to decrease tissue eosinophilia, but the underlying mechanisms are not known. We evaluated the expression of IL-12R and the effect of IL-12 on eosinophil survival. In situ hybridization demonstrated the presence of mRNA and immunoreactivity for IL-12Rbeta1 and -beta2 subunits in human peripheral blood eosinophils. Surface expression of IL-12Rbeta1 and -beta2 subunits on freshly isolated human eosinophils was optimally expressed after incubation with PMA. To determine the functional significance of IL-12R studies, we studied cell viability and apoptosis. Morphological analysis and propidium iodide staining for cell cycle demonstrated that recombinant human IL-12 increased in vitro human eosinophil apoptosis in a dose-dependent manner. Addition of IL-5 together with IL-12 abrogated eosinophil apoptosis, suggesting that IL-12 and IL-5 have antagonistic effects. Our findings provide evidence for a novel role for IL-12 in regulating eosinophil function by increasing eosinophil apoptosis.

Serum interleukin-5 in aspirin-induced asthma

BACKGROUND

Eosinophilopoetic cytokine IL-5 enhances cysteinyl-leukotriene (cys-LT) synthesis in eosinophils in vitro. In patients with aspirin-induced asthma (AIA) bronchial biopsies revealed eosinophil infiltration and a marked increase in IL-5 positive cells.

OBJECTIVE

We wondered whether in AIA patients the bronchial IL-5 increase is reflected in peripheral blood, and if so, whether it is related to overproduction of cys-LT.

METHODS

In 11 stable patients with AIA, 32 with ATA (aspirin-tolerant asthma) and in 16 controls we measured serum IL-5 concentrations and urinary LTE4, believed to reflect global cys-LT production.

RESULTS

Serum IL-5 was detectable in 12 of 43 asthmatics, but in none of the control subjects. It was highest in the ATA group and differed significantly from the controls. There was no significant difference in IL-5 levels between: (i) the asthmatic groups studied, and (ii) AIA patients and controls. No relationship was found between serum IL-5 and urinary cys-LT.

CONCLUSION

Overexpression of IL-5 reported in the airways of aspirin-sensitive patients with asthma was not reflected in their blood. If IL-5 affects cys-LT production, it is rather in the bronchi of the patients than in the blood.

Eotaxin expression after segmental allergen challenge in subjects with atopic asthma

Expression of pulmonary eotaxin protein and mRNA was determined in six subjects with atopic asthma and five nonatopic normal subjects. Levels of eotaxin expression and eosinophil mobilization were compared before and after segmental allergen challenge in subjects with atopic asthma. In the absence of allergen challenge, we found significantly higher levels of eotaxin in the bronchoalveolar lavage (BAL) fluid of subjects with asthma than in that of normal subjects (25 +/- 3 versus 15 +/- 2 pg/ml, p < 0.05). BAL eotaxin levels increased after segmental allergen challenge in all six subjects with atopic asthma tested, with a mean increase from 22 +/- 4 to 53 +/- 10 pg/ml (p = 0.013). Segmental allergen challenge was associated with a significant increase in the percentage of BAL macrophages and eosinophils that were immunopositive for eotaxin. Eotaxin mRNA was detectable by northern analysis in BAL cells exclusively from allergen-challenged segments. Allergen- induced increases in eotaxin levels were strongly associated with increases in BAL eosinophil recovery (r(2) = 0.88, p = 0.0036). Segmental allergen challenge also increased eotaxin expression in airway epithelial and endothelial cells obtained by endobronchial biopsy. These findings demonstrate, for the first time, that the airways of subjects with allergic asthma respond to allergen by increasing eotaxin expression. The tissue loci of eotaxin expression, the levels of eotaxin recovered in BAL fluid, and the association of eotaxin levels with eosinophil mobilization suggest either that eotaxin plays a mechanistic role in allergen-induced airway eosinophilia or that it serves as a biomarker for the causal mechanisms.

Effect of natural allergen exposure on non-specific bronchial reactivity in asthmatic farmers

The aim of the study was to assess the seasonal variability of non-specific bronchial reactivity (NSBR) evaluated with methacholine in asthmatic farmers allergic to pollens. Twenty farmers (16 male and four female) with allergy to pollens, e.g. 'Graminae' and 'Parietaria', entered the study. None of the patients had been previously treated with specific immunotherapy. Patients underwent a methacholine challenge at the first visit and then in the subsequent seasons. Four groups of tests were obtained according to the period when the challenge was performed. Group 1: challenges performed in December, January and February; group 2 in March, April and May; group 3 in June, July and August; group 4 in September, October and November. PD20 values were expressed as the natural logarithm of the cumulative dose of methacholine causing at least a 20% fall in FEV1. Bronchial hyperreactivity was highest in summer, followed by spring and autumn; in winter it was much lower. Multiple group analysis (ANOVA) showed statistically significant differences between the groups (P < 0.01). When the groups were compared individually, statistically significant differences existed only between group 1 (winter) and each of the other groups, respectively 2 (spring) (P = 0.02), 3 (summer) (P = 0.004) and 4 (autumn) (P = 0.02). The results underlined the importance of allergic inflammation in determining changes in NSBR. In the region where the study was carried out (central Italy), the grass and Paretaria pollination lasts from March to November. Therefore, farmers had a progressive increase in NSBR from spring to summer and a decrease in fall as a consequence of the varying pollen concentration in different seasons. The level of allergen exposure is, in fact, the main factor that determines the severity of bronchial inflammation, thus affecting NSBR.

Sensitization to environmental antigens in asthmatic children from a central Italian area

This study was designed to evaluate the frequency of respiratory allergens in different age groups of asthmatic atopic children in the Chieti-Pescara area. We examined a pediatric population (507 children) aged between 1 to 17 years (mean 6.62 +/- 2.9). All the children were submitted to a panel of skin prick tests (SPT) for 12 common aeroallergens: Grass Pollens (G.), Parietaria (P.), Olive (O.), Artemisia (A.), Ragweed (R.), Dermatophagoides Pteronyssinus and Dermatophagoides Farinae (D.P. & D.F.), Cat and Dog dander (C.D.), Feathers (F.), Alternaria (Al.), Aspergillus (As.). All the subjects gave positive result to one or more allergens. The population was subdivided in to 4 groups according to their age (Group A: 1-3 years; Group B: 4-6 years; Group C: 7-9 years; Group D: 10-17 years). In each age group, we determined the number of subjects with 1, 2, 3, 4 or 5 and more than 5 positive SPT and the prevalence of positive SPT for different allergens. We found that 74% of 507 patients showed positive reaction to Dermatophagoides Pt, 71% to Dermatophagoides Fa, 45% to Grass, 23% to Parietaria, 21% to Olive, 17% to Artemisia, 17% to Cat's or Dog's danders, 13% to Alternaria, 5.9% to Ragweed, 5.9% to Feathers, and 4% to Aspergillus. In addition we detected that 12% of children examined were monosensitized; 56% were sensitized to 2 or 3 allergens; 22% were sensitized to 4 or 5 allergens, and then 8% were polysensitized to > 5 allergens. The allergy to grass pollens and to house dust mites was the most frequent in monosensitized. In the older patients, we found an increase in number of positives SPT to several allergens, and an increase in the frequency of Gr., P. and O. allergy, while the house dust mites sensitization remained constant in all groups and represented the dominant cause of asthmatic symptoms in this population. Our data confirm the importance of age in determining a respiratory polysensitization. In conclusion, our data suggest that house dust mites (D.P. and D.F.) and grass pollens are the most common allergens in asthmatic children of the Chieti-Pescara area.

Role of IL-9 in the pathophysiology of allergic diseases

Considerable evidence from both human and animal studies indicates that CD4(+) cells are the predominant cell type involved in the regulation of airway inflammation through the expression of T(H)2-type cytokines. The effects of T(H)2-type cytokines, particularly IL-4 and IL-5, on inflammatory and structural cells in airways have been studied in great detail. They were shown to be important for inflammatory cell maturation, activation and proliferation, IgE production, chemokine expression, mucus secretion, and bronchial hyperresponsiveness. Recent work has shown the potential importance of another T(H)2-type cytokine, IL-9. The development of transgenic mice overexpressing IL-9 has suggested a key role for this cytokine in the development of the asthmatic phenotype, including eosinophilic inflammation, bronchial hyperresponsiveness, elevated IgE levels, and increased mucus secretion. IL-9 has been shown to act on many cell types involved in asthma, including T cells, B cells, mast cells, eosinophils, neutrophils, and epithelial cells, and thus might be important in the pathophysiology of allergic asthma.

Dietary n-3 and n-6 polyunsaturated oils and airway contractility

Recent reports suggest modulation of chronic obstructive pulmonary disease by dietary polyunsaturated fatty acids. In the present study, we re-examined this possibility by using an established animal model of pulmonary sensitisation. Adult guinea pigs were fed diets supplemented (10% w/w) with either olive, canola or safflower oil for 4 weeks before sensitising with ovalbumin and continuing on various diets for a further 6 week period. Neither the contraction following ovalbumin challenge, nor the responses to histamine, carbachol and various eicosanoid mediators - prostaglandin F(2 alpha), leukotriene C(4), thromboxane mimetic U44619 - of isolated segments of airway tissue were altered (P>0.05, ANOVA) by the dietary lipid treatment. Lipid analysis showed changes in membrane linoleic acid (18:2n-6) and alpha -linolenic acids (alpha 18:3n-3) in lung phospholipids consistent with dietary intakes. However, no significant further desaturation/elongation of these dietary precursors was evident. Ovalbumin induced contraction was fully reversed by the lipoxygenase inhibitor esculetin whilst indomethacin resulted in a slight increase possibly due to the inhibition of bronchodilator prostanoids. Results confirm that under the conditions employed airway function was not influenced by the variable dietary intakes of n-3 and n-6 PUFA.

Th2 cytokines and asthma. The role of interleukin-5 in allergic eosinophilic disease

Interleukin-5 is produced by a number of cell types, and is responsible for the maturation and release of eosinophils in the bone marrow. In humans, interleukin-5 is a very selective cytokine as a result of the restricted expression of the interleukin-5 receptor on eosinophils and basophils. Eosinophils are a prominent feature in the pulmonary inflammation that is associated with allergic airway diseases, suggesting that inhibition of interleukin-5 is a viable treatment. The present review addresses the data that relate interleukin-5 to pulmonary inflammation and function in animal models, and the use of neutralizing anti-interleukin-5 monoclonal antibodies for the treatment of asthma in humans.

Neutrophils enhance eosinophil migration across monolayers of lung epithelial cells

During the late-phase asthmatic response eosinophils and neutrophils infiltrate the lungs and cause severe damage. In this study, we investigated in vitro the migration of eosinophils, in the absence and presence of neutrophils, across a monolayer of lung H292 epithelial cells. The migration of eosinophils towards the complement fragment 5a (C5a) was increased when neutrophils were added to the upper compartment of the Transwells, and decreased when neutrophils were added to the lower compartment. Moreover, neutrophils exclusively stimulated eosinophil migration towards C5a, and not towards other chemoattractants such as RANTES, IL-8 or PAF. Neutrophils and eosinophils differed in that neutrophils, but not eosinophils, rapidly inactivated C5a, suggesting that neutrophils in the upper compartment remove part of the active C5a that has diffused into the upper compartment. Indeed, we found that the addition of other C5a-degrading agents, such as human serum or carboxypeptidase B, also enhanced eosinophil migration when added to the upper compartment and decreased migration when added to the lower compartment. Taken together, these results indicate that the presence of neutrophils influences the migratory behaviour of eosinophils in vitro. The neutrophils presumably maintain a proper C5a chemotactic gradient in the transmigration model, which results in enhanced eosinophil chemotaxis.

Urinary eosinophil protein X in children with asthma: influence of atopy and airway infections

It has been suggested that urinary eosinophil protein X (U-EPX) can be used to monitor bronchial inflammation in childhood asthma. However, the influence of atopy and airway infections is not well elucidated. To determine the clinical value of measuring U-EPX in children with asthma and to evaluate the influence of atopy and airway infections, U-EPX was measured in 170 children with asthma (mean age 69 months, range 12-179 months), in 79 children with lower or upper respiratory tract infections (mean age 41 months, range 1-165 months), and in 64 controls. U-EPX was elevated in children with acute asthma (median 132 microg/mmol of creatinine, quartiles 77-195 microg/mmol of creatinine, n = 51, p <0.001) and chronic asthma (median 93 microg/mmol of creatinine; quartiles 46-149 microg/mmol of creatinine, n = 119, p <0.01) compared with controls (median 54 microg/mmol of creatinine, quartiles 40-89 microg/mmol of creatinine, n = 39). Atopic children had higher levels of U-EPX than non-atopics with acute asthma (median 155 microg/mmol of creatinine, quartiles 113-253 microg/mmol of creatinine, n = 27, vs. median 102 microg/mmol of creatinine, quartiles 56-168 microg/mmol of creatinine, n = 24, p <0.05), as well as with chronic asthma (median 110 microg/mmol of creatinine, quartiles 65-162 microg/mmol of creatinine, n = 63, vs. median 60 microg/mmol of creatinine, quartiles 39-123 microg/mmol of creatinine, n = 56, p <0.01). In chronic asthma, children without atopy had levels of U-EPX similar to values of controls; levels were similar in symptomatic and asymptomatic patients, and not influenced by treatment with inhaled corticosteroids. Moreover, U-EPX levels were higher in children with pneumonia (median 207 microg/mmol of creatinine, quartiles 111-280 microg/mmol of creatinine, n = 35, p <0.001), laryngitis (median 109 microg/mmol of creatinine, quartiles 65-161 microg/mmol of creatinine, n = 24, p <0.01), and rhinitis (median 172 microg/mmol of creatinine, quartiles 123-254 microg/mmol of creatinine, n = 19, p <0.001) than in controls (median 62 microg/mmol of creatinine, quartiles 41-93 microg/mmol of creatinine, n = 64). There was significant overlap among all groups of children with disease, as well as between children with disease and controls. Hence, U-EPX may reflect differences in eosinophil involvement and activation between children with atopic and non-atopic asthma, but the individual spread within groups and the influence of airway infections limits the clinical value of U-EPX in childhood asthma.

Interleukin-2 inhibits eosinophil migration but is counteracted by IL-5 priming

Conflicting data on the role of interleukin-2 in the recruitment of eosinophil granulocytes (EOS) to sites of inflammation have been presented. The objective of the present study was to investigate the effect of recombinant human IL-2 and anti-IL-2 on the migration of purified blood EOS. Neutralizing antibodies to IL-2 were added to a cytokine mixture with significant eosinophil chemotactic activity (ECA), and afterwards the ECA was tested on EOS from both normal and allergic donors. EOS migration was measured by a modification of the Boyden technique, using a 48-well microchemotaxis chamber. Recombinant human IL-2 was either added to the lower compartment of the chemotaxis chamber, or to the EOS for a pre-incubation period of 20 min, before migration assays towards the chemotaxins were performed. Anti-IL-2 caused a significant increase of EOS migration towards the cytokine mixture. Pre-incubation of the EOS with rhIL-2 inhibited the chemotaxis towards RANTES, PAF, IL-8 and eotaxin, and EOS migration towards IL-2 was lower than that towards buffer. These effects were more pronounced on EOS from normal than from allergic donors. Priming of the EOS with IL-5 prevented the inhibitory effect of IL-2. We hypothesize that IL-2 acts as an autocrine regulator of EOS migration, and that this inhibitory effect may be downregulated in allergy, allowing an increased migration of EOS towards chemotactic factors.

Erythromycin modulates eosinophil chemotactic cytokine production by human lung fibroblasts in vitro

Recent studies suggest that erythromycin can suppress the production of some cytokines and may be an effective treatment for asthma. Eosinophil chemotactic cytokines have been suggested to contribute to the pathogenesis of asthma by the recruitment of eosinophils. We hypothesized that erythromycin modulates eosinophil chemotactic cytokine production. To test the hypothesis, we evaluated the potential of erythromycin to modulate the release of eosinophil chemoattractants from the human lung fibroblast cell line HFL-1. HFL-1 released eotaxin, granulocyte-macrophage colony-stimulating factor, and regulated and normal T-cell expressed and presumably secreted (RANTES) in response to interleukin-1beta or tumor necrosis factor alpha. Erythromycin attenuated the release of these cytokines and eosinophil chemotactic activity by the HFL-1. The suppressive effect on eotaxin was the most marked of these cytokines. Erythromycin therapy also suppressed eotaxin mRNA significantly. These results suggest a mechanism that may account for the apparent beneficial action of macrolide antibiotics in the treatment of allergic airway disorders.

Relationship between IgE positive cell numbers and serum total IgE levels in mice treated with trimellitic anhydride and dinitrochlorobenzene

Although increased total serum IgE levels have been suggested as being predictive parameters of airway hypersensitivity caused by low molecular weight chemicals, it is not yet clear what level of serum total IgE in chemically-treated animals would translate to potential risk of inducing an immediate type hypersensitivity in human beings. Quantitative determination of IgE-bearing positive cells induced by chemicals in the tissue, particularly in respiratory airway, could help to resolve this problem. In BALB/c mice, serum total IgE concentrations and tissue IgE-bearing positive cell numbers were investigated following topical exposure to the chemicals, trimellitic anhydride (TMA) and dinitrochlorobenzene (DNCB), known in human as a respiratory and dermal sensitizer, respectively. In groups of mice 8 and 10 weeks of age, there were less individual variations in 25% TMA-induced serum total IgE increase than in other groups of mice 6, 12 and 16 weeks of age. When chemical concentrations of 1, 2 and 3% DNCB and of 6.25, 12.5 and 25% TMA were studied, we observed that the increase in IgE was dose-dependent for both chemicals, r=0.96; P=0.03 for DNCB and r=0.99; P=0.002 for TMA. However, the increase in serum total IgE induced by TMA was at least twice that induced by DNCB and was associated with the numbers of IgE bearing cells in the tracheal lamina propria (r=0.67, P=0.0003). A respiratory hypersensitivity caused by TMA, but not by DNCB, may be partly due to the presence of immuno effector cells bearing IgE at their surface in airway microenvironments, and their presence might be related to the higher level of serum total IgE. The IgE bearing positive cells could, therefore, help to identify chemicals which have the potential risk of inducing an immediate type hypersensitivity in humans.