Asthma and inflammation

Eosinophil cationic protein in serum from nonatopic and asymptomatic atopic individuals after standardized blood clotting at 37 degrees C

Eosinophil cationic protein (ECP) and ECP/eosinophil ratio were measured in 223 apparently healthy subjects. The serum sample for ECP measurement was obtained by standardized clotting of the blood sample for 2 hours at 37 degrees C. Eosinophil count, ECP concentration and ECP/eosinophil ratio were no different between men (n = 122) and women (n = 101). Reference ranges for serum ECP and ECP/eosinophil ratio were 12-99 micrograms/L and 61-367 micrograms ECP per 10(9) eosinophils, respectively. Serum ECP and blood eosinophil count were positively correlated (y = 141x + 18, R2 = 0.45, P < 0.001). The ECP/eosinophil ratio, however, was found to decrease with increasing eosinophil count. Twenty-three per cent of the apparently healthy subjects were found to have a positive score for immunoglobulin E antibodies specific to inhalant allergens, and thus were considered atopic. Serum ECP concentrations and eosinophil counts were significantly higher in this group compared with the non-atopic group. In this healthy population no decision level for either eosinophil count, serum ECP or ECP/eosinophil ratio could be found that discriminated atopic from non-atopic individuals.

Increased levels of IL-5 positive peripheral blood eosinophils and lymphocytes in mild asthmatics after allergen inhalation provocation

BACKGROUND

In allergic inflammation eosinophils and TH2-like lymphocytes are supposed to be the major effector cells and considered to contribute as cellular source of the key cytokine interleukin (IL)-5.

OBJECTIVE

The purpose of this study was to enable detection of IL-5 containing leucocytes and to investigate whether the number of these cells in the blood circulation differed between healthy and asthmatics before and after allergen provocation.

METHODS

The distribution of intracellular IL-5 in human peripheral blood eosinophils (PBE) and lymphocytes (PBL) has been investigated using fixation and cell membrane permeabilization with octyl-glucopyranoside, the FOG-method, and flow cytometry. The intracellular staining was performed on leucocytes without any prior purification and in vitro stimulation. The specificity of IL-5 binding to intracellular compartment of both PBE and PBL was confirmed by complete inhibition with human recombinant IL-5.

RESULTS

Preformed intracellular IL-5 was detected in the main population of PBE (> 70%) in both healthy individuals and asymptomatic patients. Moreover, preformed intracellular IL-5 was also detected in 4.8% and 2.4% of PBL from healthy individuals and asymptomatic patients, respectively. There was a correlation between the absolute number of PBE and IL-5 positive PBE. In patients with pollen-related asthma, the number of IL-5 positive PBE and PBL increased significantly 24 h after an allergen inhalation provocation (P < 0.05). In the healthy control group no differences regarding IL-5 positive PBE and PBL were obtained pre- and post-allergen challenge.

CONCLUSIONS

In patients with mild allergic asthma, but not in healthy individuals, allergen provocation induces an increased absolute number of IL-5 positive PBE and PBL. The reason for the relatively high number of IL-5 positive PBL is unclear, but a plausible explanation might be that other lymphocyte subsets besides CD4+ TH2 can produce IL-5. However, enumeration of IL-5 positive leucocytes may be used as an activity marker and also be a useful tool in monitoring the inflammation in asthma.

Association of 3 gene polymorphisms with atopic diseases

BACKGROUND

Various peptidases, including angiotensin-converting enzyme (ACE), inactivate some inflammatory peptides that are considered to influence the pathogenesis of atopic diseases. This enzyme is also involved in the conversion or activation of 2 bronchoconstriction mediators: angiotensin II from angiotensinogen and endothelin (ET), respectively.

OBJECTIVE

We tested a hypothesis that asthma or other atopic diseases are associated with insertion/deletion ACE, M235T angiotensinogen, and TaqI ET-1 gene polymorphisms.

METHODS

A case-control approach was used in the study. Healthy subjects (141 persons) were used as control subjects, and 231 patients with histories of atopic asthma, allergic rhinitis, atopic dermatitis, or a combination thereof were studied. ACE genotype was determined by PCR, angiotensinogen M235T and ET-1 by PCR, and restriction analysis by AspI and TaqI, respectively.

RESULTS

We found the significant association of the insertion/deletion polymorphism of the ACE, as well as that of M235T polymorphism of the angiotensinogen genes, with the group of patients with atopic diseases ( P =.0025 and P =.0204, respectively). No difference was proved for the intron 4 (position 8000) polymorphism in the ET-1 gene when comparing the atopic patients with the control group (P =.1774). A significant difference was found between groups of patients with both asthma and rhinitis and patients without both respiratory atopic diseases (P =.0033).

CONCLUSION

It follows that the examined polymorphisms in the genes for ACE, angiotensinogen, and ET-1 could participate in the etiopathogenesis of atopic diseases.

Biology of IL-5 in health and disease

LEARNING OBJECTIVES

Reading this article will increase the readers' knowledge of the biology of interleukin-5 (IL-5), an important cytokine. The immune and inflammatory responses of any organism are the basis of the defense mechanism ensuring its survival. The role of IL-5 in these processes, as well as in the pathogenesis of various diseases has been discussed along with the effects of various pharmacologic agents on the production and function of IL-5.

DATA SOURCES

A detailed literature search was performed. Studies considered relevant and important, in all languages, which involved humans and animals were used.

STUDY SELECTION

Information was obtained only from peer reviewed journals.

RESULTS

Interleukin-5 is normally produced by T-cells, mast cells, and eosinophils while Reed Sternberg and Epstein Barr virus (EBV) transformed cells also produce IL-5. Monoclonal antibodies (mAb) to IL-5 are potent inhibitors of IL-5 mediated tissue damage, secondary to eosinophil infiltration. The majority of the studies on IL-5 are preliminary, often the information is obtained from animal studies or in vitro systems and occasionally from pathologic tissue analysis. This along with the absence of confirmatory studies is a limiting factor. Nonetheless, the role of IL-5 in allergic and immunologic disease and asthma may be central to their pathogenesis.

CONCLUSIONS

Interleukin-5 is an important molecule that is participant to many processes that maintain health and are involved directly or indirectly in the pathogenesis of disease. Some pharmacologic agents can modify IL-5 production in vivo. Development of selective inhibitors of IL-5 may have a potential use for specific therapy of certain autoimmune, inflammatory, and neoplastic diseases.

Inhibition of Matrix Metalloproteinases Prevents Allergen-Induced Airway Inflammation in a Murine Model of Asthma

Although matrix metalloproteinases (MMPs) have been reported to play crucial roles in the migration of inflammatory cells through basement membrane components in vitro, the role of MMPs in the in vivo accumulation of the cells to the site of inflammation in bronchial asthma is still obscure. In this study, we investigated the role of MMPs in the pathogenesis of bronchial asthma, using a murine model of allergic asthma. In this model, we observed the increase of the release of MMP-2 and MMP-9 in bronchoalveolar lavage fluids after Ag inhalation in the mice sensitized with OVA, which was accompanied by the infiltration of lymphocytes and eosinophils. Administration of tissue inhibitor of metalloproteinase-2 to airways inhibited the Ag-induced infiltration of lymphocytes and eosinophils to airway wall and lumen, reduced Ag-induced airway hyperresponsiveness, and increased the numbers of eosinophils and lymphocytes in peripheral blood. The inhibition of cellular infiltration to airway lumen was observed also with tissue inhibitor of metalloproteinase-1 and a synthetic matrix metalloproteinase inhibitor. These data suggest that MMPs, especially MMP-2 and MMP-9, are crucial for the infiltration of inflammatory cells and the induction of airway hyperresponsiveness, which are pathophysiologic features of bronchial asthma, and further raise the possibility of the inhibition of MMPs as a therapeutic strategy of bronchial asthma.

Immunological changes associated with clinical improvement of asthmatic children subjected to psychosocial intervention

In the present study we evaluated the impact of a program of psychosocial intervention (PSI) on the immunological status and the clinical management of a group of asthmatic children of an island population in Venezuela. We studied a total of 35 asthmatic children who belonged to either a PSI group (19 patients) or a control group (16 patients), both of which received conventional antiasthmatic treatment. The PSI group received, in addition, a 6-month psychosocial intervention program which included relaxation, guided imagery, and self-esteem workshops. During the PSI period, the number of asthmatic episodes and the use of bronchodilator medication were significantly reduced, and pulmonary function was significantly improved, compared to the 6 months before intervention. There was also a significant reduction in the specific IgE responses against the most important allergen in these children, the intestinal parasite Ascaris lumbricoides. PSI resulted in a significant increase of NK cells, an augmented expression of the T-cell receptor for IL-2, and a significant decrease of leukocytes with low affinity receptors for IgE. In fact, these surface markers became similar to those of nonasthmatic children from both Coche Island and the mainland. None of these clinical or immunological changes were seen in the control group of asthmatics who did not undergo PSI. These results are consistent with the possibility that PSI induces immunological alterations that are responsible for the clinical and physiological improvements observed in the study group.

Administration of interleukin-12 prevents mite Der p 1 allergen-IgE antibody production and airway eosinophil infiltration in an animal model of airway inflammation

The aim of the present study was to examine the in vivo effect of interleukin (IL)-12 on a murine model of asthma induced by Dermatophagoides pteronyssinus-derived Der p 1 allergen. C57BL/6 mice immunized with Der p 1 allergen adsorbed to alum/pertussis toxin developed a T-helper type 2 (Th2)-dominant immune response characterized by the presence of IgE antibody, airway eosinophil infiltration and increased production of Th2 cytokine. Intraperitoneal injection of IL-12 (1 or 0.1 microg per day) for 5 days (day -1 to +3) simultaneously with each immunization, inhibited the production of IgE and IgG1 antigen-specific antibodies, whereas production of IgG2a was strongly enhanced. In addition, mice receiving both doses of IL-12 showed a strong inhibition of IL-5 but up-regulation of IFN-gamma production by spleen cells stimulated with antigen. Administration of IL-12 also prevented antigen-induced eosinophil infiltration into the bronchoalveolar area in a dose-dependent manner and the primary inflammatory mediator serotonin in bronchoalveolar lavage (BAL) fluids was also reduced significantly. Taken together, the data indicate that IL-12 has a potent immunomodulatory effect on house-dust-mite-induced allergic disorders and may be used as an efficient agent for immunotherapy.

Mechanisms of glucocorticoid reduction in asthmatic subjects treated with intravenous immunoglobulin

BACKGROUND

Intravenous immunoglobulin (IVIG) has been used as an oral glucocorticoid (GC)-sparing agent in patients with steroid-dependent asthma. Despite its use, little is known regarding its mechanism of action.

OBJECTIVE

We sought to determine whether the GC-sparing effects of IVIG in severe asthma are related to improved GC receptor (GCR)-binding affinity and subsequent enhanced GC sensitivity.

METHODS

In an open-label study, 11 steroid-dependent asthmatic subjects (6 GC-insensitive, 5 GC-sensitive) received monthly infusions of IVIG (2 g/kg) for 6 months. Peak expiratory flow rates and oral GC dose were recorded daily, and spirometry was performed monthly. Blood was drawn for lymphocyte stimulation assays and GCR assays at baseline and after 3 and 6 months of therapy. Lymphocytes were stimulated ex vivo with PHA in the presence and absence of IVIG and increasing concentrations of dexamethasone (DEX).

RESULTS

IVIG resulted in significant reductions in oral GC dose (P <.02), number of GC bursts (P =.033), and hospitalizations (P =.001) after 6 months of IVIG. Those with GC-insensitive asthma responded equally well to IVIG as those with GC-sensitive asthma. Associated with the improved clinical efficacy, IVIG acted synergistically with DEX in suppressing lymphocyte activation as measured by a shift in the DEX dose-response curve by 1 log-fold (P =.03). IVIG therapy was also associated with significantly improved GCR-binding affinity (P =.01).

CONCLUSIONS

IVIG resulted in significant reductions in oral GC requirements and hospitalizations in a group of patients with severe asthma, with IVIG being as effective in patients with GC-insensitive asthma as in patients with GC-sensitive asthma. IVIG therapy acted synergistically with DEX in suppressing lymphocyte activation and significantly improved GCR-binding affinity after 3 and 6 months of therapy.

The role of interleukin-5, interleukin-8 and RANTES in the chemotactic attraction of eosinophils to the allergic lung

BACKGROUND

Bronchoalveolar lavage (BAL) fluid from patients with birch-pollen allergy lavaged during the season showed an elevated chemotactic activity for eosinophils compared with BAL fluid from the same patients before the start of the season.

AIM

The aim of this study was to identify the eosinophil chemotactic agents in the BAL fluid, to compare these findings with in vitro studies on selected cytokines, and to investigate the interactions between these cytokines.

METHODS

Neutralizing antibodies for interleukins (IL) -2, -5 and -8, RANTES and leukaemia inhibitory factor (LIF) were added to the BAL fluid, and the chemotactic activity was tested with eosinophils from allergic donors. Eosinophils from healthy donors were preincubated with IL-5 in order to mimic the primed state of eosinophils from allergics, and the migration towards recombinant IL-5, IL-8, and RANTES in different combinations was measured. Eosinophils from allergic donors were also used.

RESULTS

Anti-IL-5, anti-IL-8 and anti-RANTES inhibited the chemotactic activity in the BAL fluid. Recombinant RANTES induced migration, which was enhanced by preincubation of the cells with IL-5. Only eosinophils from symptomatic allergics responded to IL-8, and IL-5 was not sufficient to prime normal eosinophils in vitro to an IL-8 response. A negative correlation was found between the level of in vivo activation of the cells and their response to IL-5, and a positive correlation with the response to RANTES.

CONCLUSION

IL-8 and RANTES are important for eosinophil accumulation to the lung of pollen-allergic asthmatics. IL-5 alone may not be responsible for the priming of eosinophils in vivo, but is an essential cofactor for the other chemoattractants.

Repeated allergen challenge as a new research model for studying allergic reactions

Repeated allergen challenge might be a more relevant model for studying symptomatic disease, because it gives more information on the patient's handling of chronic allergen exposure. Thus, this experimental model has more resemblance to the situation of natural allergen exposure, and the allergen load can be standardized. However, the response to repeated allergen challenge in individual patients can show a large variation, that is from a strongly enhanced response to complete diminution of the response. Successful allergen immunotherapy can change the response pattern of repeated allergen challenge in the skin into down-regulation of the late reaction. Chronic or repeated allergen exposure may result in an enhanced allergen-specific allergic response, involving allergen-specific T-cell activation. Different subsets of T cells can exert either activating or suppressive effects on inflammatory cells involved in subsequent allergic reactions. CD8+ T cells might exert suppressive effects, because they seem to be associated with a subsequent down-regulation of the late skin reaction after repeated allergen challenge (Fig. 4). Further studies are needed to compare the responses to repeated allergen challenge with the response to natural seasonal allergen exposure in the same patients and to explore possible underlying mechanisms using, for example, nasal biopsies.

Specific immunoglobulin E, interleukin-4, and soluble vascular cell adhesion molecule-1 in sera in patients with seasonal allergic rhinitis

This study included 23 nonatopic volunteers and 84 patients with seasonal allergic rhinitis due to Japanese cedar pollen. Serum interleukin-4 (IL-4) and soluble vascular cell adhesion molecule-1 (sVCAM-1) in the patients were significantly higher than those in the nonatopic individuals, even outside of the pollen season. Both the good responders and the poor responders to antihistamine tablets showed significant increases in IL-4 and specific IgE during the pollen season, whereas such seasonal increases were not observed in the good responders to immunotherapy. Seasonal increases in IL-4 were significantly correlated with those of specific IgE. However, seasonal increases in sVCAM-1 were not significant. Seasonal increases in sVCAM-1 were not significantly different between the good responders and the poor responders to pharmacotherapy or immunotherapy. In conclusion, serum IL-4 and sVCAM-1 are increased in patients with seasonal allergic rhinitis, even outside of the pollen season; this finding might suggest underlying preponderant in vivo activation of T helper cell-2-like cells and inflammatory events in seasonal allergic rhinitis. A seasonal increase in IL-4 in sera might be at least partly involved in the seasonal increase in specific IgE in sera. Immunotherapy's inhibitory effect on IL-4 production and specific IgE response might be one of its working mechanisms.

A study of novel antiallergic agents with eosinophilic infiltration inhibiting action

The antiallergic action of a series of novel mono-O-substituted trimethylhydroquinones was investigated. Among this series of the compounds, 4-[4-[4-(diphenylmethyl)-1-piperazinyl]butoxy]-2,3,6- trimethylphenol (compound 3) showed a potent antihistaminic action (pA2 = 7.11) and an antiasthmatic action (100 mg/kg. p.o) on sensitized guinea pigs. Moreover, this compound exhibited a strong eosinophilic infiltration inhibiting action on sensitized mice (100 mg/kg p.o.).

Effect of natural grass pollen exposure on exhaled nitric oxide in asthmatic children

Exhaled nitiric oxide (NO) is increased in exhaled breath of asthmatic patients. The aim of this study was to investigate the longitudinal changes of exhaled NO outside and during the pollen season in pollen-allergic asthmatic children. Twenty-one children (age 6 to 16 yr), with a seasonal allergic asthma sensitive to grass pollen, underwent measurements of exhaled NO and pulmonary function before (March), during (May), and after (November) the pollen season. Exhaled NO was measured by a tidal breathing method with a chemiluminescence analyzer and NO steady-state levels were recorded. The timing of the measurements during the pollen season was based on the atmospheric pollen count. Exhaled NO values of asthmatic children were compared with those of 21 sex- and age-matched healthy children. Pulmonary function and symptoms of asthma were also evaluated at each visit. The mean value of exhaled NO before the grass season was 12.7 +/- 5.1 ppb (mean +/- SD), significantly higher when compared with controls (7.8 +/- 2.7 ppb, p < 0.001). In the pollen season there was a significant (p < 0.001) twofold increase in exhaled NO (21.4 +/- 7.6 ppb) that, after the season, returned to values similar (12.8 +/- 5.8 ppb, p = NS) to those found before the season. There were no significant changes in FEV1 before and during the season (98.6% predicted versus 101% predicted, p = NS). We conclude that natural allergen exposure is related to an increase of exhaled NO in asthmatic grass pollen-allergic children even in absence of significant changes in airways function. We speculate that measurement of exhaled NO could be a sensitive noninvasive marker of asthma disease activity.

STAT6 deficiency in a mouse model of allergen-induced airways inflammation abolishes eosinophilia but induces infiltration of CD8+ T cells

BACKGROUND

The TH2-type cytokines have been reported to contribute to the asthmatic response. STAT6 has an essential role in IL-4 signalling and in production of TH2 cytokines from T cells and is involved in IgE and IgG1 responses after nematode infections, indicating that STAT6 has an important role in allergic diseases.

OBJECTIVE

In this study we investigated the effects of STAT6 deficiency on allergen-induced airways inflammation in mice.

METHODS

Both ovalbumin (OVA)-sensitized STAT6 deficient (STAT6-/-) mice and wild-type C57BL/6 mice were challenged with aerosolized OVA. Changes in inflammatory cell infiltration and cytokine levels in lung tissue as well as serum immunoglobulin levels were analysed in OVA-challenged STAT6-/- and wild-type mice.

RESULTS

The eosinophilia and lung damage normally resulting from aeroallergen challenge were not seen in STAT6-/- mice. Expression of TH2 cytokines (IL-4 and IL-5) in the lung tissue as well as IgE and IgG1 responses after OVA challenge were profoundly reduced in STAT6-/- mice, whereas expression of IFNgamma was the same in STAT6-/- mice and wild-type mice after OVA challenge. Immunocytochemical analysis of T cells showed the infiltration of CD4+ T cells but not CD8+ T cells increased into the lung of wild-type mice after OVA challenge. However, the OVA-exposed STAT6-/- mice demonstrated the infiltration of both CD4+ T cells and CD8+ T cells with a significant increase in percentage and total number of CD8+ T cells compared with OVA-exposed wild-type mice.

CONCLUSION

These results indicate that factors which signal through STAT6 are important regulators of eosinophilia of allergic airway inflammation, regulating TH2-type cytokine production both in CD4+ T cells and CD8+ T cells.

Long-term analysis of allergen-specific T cell clones from patients with asthma treated with allergen rush immunotherapy

Rush immunotherapy (RI), a modified allergen-specific immunotherapeutic procedure, is an effective treatment for extrinsic (atopic) asthma, although the precise mechanism of its action is unclear. We have thus investigated the effect of RI on T cell response in seven mite-allergen-sensitive asthmatic patients who were successfully treated with RI. The proliferative response to mite allergen profoundly decreased after 3 months of therapy compared to the response before therapy; the response, however, recovered 18 months after RI. Regarding cytokine production patterns of mite-specific T cells, RI brought about a shift in cytokine profiles from Th2 to Th0 or Th1 in mite-specific T cell clones. The data indicate that the efficacy of RI is due to modification of T cell responses to mite antigens. Allergen RI results in the conversion of Th2 to Th1 and Th0 cells and/or selection of Th1 and Th0 cells over Th2 cells and thus may improve both clinical symptoms and airway inflammation in asthmatics.

Regulation of human mast cell and basophil function by cAMP

1. Mast cells and basophils are important in mediating allergic disorders such as asthma. Activation of these cells results in the release of a wide variety of mediators that can promote inflammatory responses. 2. Receptor-mediated activators of adenylate cyclase such as the beta-adrenoceptor agonist, isoprenaline, and prostaglandin E2 (PGE2) are effective at inhibiting mediator release from human lung mast cells (HLMC) but not basophils. In HLMC, both isoprenaline and PGE2 elevate and sustain increases in cyclic adenosine 3',5'-monophosphate (cAMP) whereas in basophils, both compounds cause transient increases in cAMP. 3. Non-selective inhibitors of phosphodiesterase (PDE) such as theophylline and 3-isobutyl-1-methylxanthine are effective inhibitors of mediator release from both HLMC and basophils and both compounds cause elevations of cAMP that are sustained in both cell types. 4. Studies with selective inhibitors of PDE indicate that the cAMP-specific PDE, PDE 4, regulates the activity of basophils but not HLMC. The nature of the PDE regulating HLMC responses is uncertain. 5. These data indicate that agents that induce and sustain elevations in intracellular cAMP attenuate the stimulated release of mediators from mast cells and basophils. However, the responsiveness of HLMC and basophils to selected cAMP-active agents differs.

Is serum eosinophil cationic protein in bronchiolitis a predictor of asthma?

To examine their possible predictive value for the development of asthma, the serum concentration of eosinophil cationic protein (ECP) and the total eosinophil count were measured at admission in 25 children aged 1-17 months hospitalized for their first episode of bronchiolitis. After an average of three years the parents of 23 index patients answered a questionnaire to determine development of asthma. Eight children were defined as having asthma at follow-up based on at least three episodes of wheezing. The remaining 15 children had experienced only one or two episodes of wheezing, and all of these children had been wheeze free for the last year. The serum concentrations of ECP were similar in children who subsequently developed asthma (8.0 microg/l; 3.6 to 14.2 (median; quartiles)) and in those who did not (12 microg/l; 4.5 to 16.8). Moreover, the total eosinophil counts were similar in asthmatic (0.10 x 10(9)/l; 0.04 to 0.20) and non-asthmatic patients (0.09 x 10(9)/l; 0.02 to 0.13). In conclusion, our study suggest that neither the serum concentration of ECP nor the total eosinophil count can predict the development of asthma when measured in children admitted for their first episode of bronchiolitis, but larger studies need to be carried out to confirm these results.

Expression of interleukin 9 in the lungs of transgenic mice causes airway inflammation, mast cell hyperplasia, and bronchial hyperresponsiveness

Interleukin (IL)-9, a pleiotropic cytokine produced by the Th2 subset of T lymphocytes has been proposed as product of a candidate gene responsible for asthma. Its wide range of biological functions on many cell types involved in the allergic immune response suggests a potentially important role in the complex pathogenesis of asthma. To investigate the contributions of IL-9 to airway inflammation and airway hyperresponsiveness in vivo, we created transgenic mice in which expression of the murine IL-9 cDNA was regulated by the rat Clara cell 10 protein promoter. Lung selective expression of IL-9 caused massive airway inflammation with eosinophils and lymphocytes as predominant infiltrating cell types. A striking finding was the presence of increased numbers of mast cells within the airway epithelium of IL-9-expressing mice. Other impressive pathologic changes in the airways were epithelial cell hypertrophy associated with accumulation of mucus-like material within nonciliated cells and increased subepithelial deposition of collagen. Physiologic evaluation of IL-9-expressing mice demonstrated normal baseline airway resistance and markedly increased airway hyperresponsiveness to inhaled methacholine. These findings strongly support an important role for IL-9 in the pathogenesis of asthma.

The use of a neural network for studying the relationship between air pollution and asthma-related emergency room visits

To establish the relationship between air pollution levels and bronchial asthma-associated emergency room (ER) visits, we adapted artificial network technology to conduct this study which focused on three different pollutants, sulphur dioxide, nitrogen oxide and ozone. The study population was comprised of adults presenting to the emergency room of a large metropolitan hospital in Israel during a 3-month period with acute exacerbation of bronchial asthma and who had a past history of intermittent airway disease compatible with bronchial asthma. The range of mean daily pollutants levels for the whole period were: O3 = 15-26 micrograms m-3, NOx = 36-108 micrograms m-3, NO = 16-70 micrograms m-3, and SO2 = 11-32 micrograms m-3. The data sets were composed of input air pollution levels and output ER visits. The first 126 data sets used for the training phase showed that maximal ER visits were mainly associated with the highest cumulative values of air pollution and mostly with nitrogen oxide. In phase two, an attempt was made to predict ER visits based on air pollution level in 49 data sets. The study findings demonstrated that ordinary network technology can be used for learning the effect of air pollution ER visits and, although limited in accuracy, to also predict future ER visits.

Blood eosinophilia and degree of sensitization to house dust mites in preschool and school children with asthma

In allergic asthma, there is convincing evidence that changes in eosinophil and lymphocyte state of activation in blood may reflect disease activity. We evaluated whether simple blood eosinophil or lymphocyte counts in atopic children with asthma could reflect the degree of allergic sensitization. Seventy-six asthmatic children, sensitized to house dust mites (HDM), in stable conditions at the time of the study, and 53 sex- and age-matched controls (CTR) were studied. As compared to CTR, allergic patients showed higher eosinophil numbers and percentages (p < 0.001) but similar lymphocyte numbers and proportions (p > 0.1). Both in CTR and in allergic patients, eosinophil counts did not correlate with lymphocyte counts (p > 0.05; each comparison) but positive correlations were observed between eosinophil numbers and percentages and paper radio immunosorbent test (PRIST) levels or radio-allergo sorbent test (RAST) classes (p < 0.001; each comparison). When allergic asthmatic individuals were subdivided according to their age into two subgroups (Gr), no differences were found in eosinophil and lymphocyte counts and in PRIST levels and RAST values between Gr1 (< or =5 years old [preschool children]) and Gr2 (>5 years old [school children]) (p > 0.05; each comparison). Interestingly, although positive correlations between eosinophil counts and PRIST levels were found in both subgroups (p < 0.05; each comparison), only in Gr2 did eosinophil counts correlate positively with RAST classes (p < 0.001). No correlations between lymphocyte counts and PRIST levels or RAST classes were demonstrated (p > 0.05; each comparison). These data suggest that although blood eosinophilia was similar in preschool and in allergic asthmatic school children sensitized to HDM, only in the oldest children did blood eosinophil counts appear to be related to the degree of HDM-specific sensitization.

Triple Role of Platelet-Activating Factor in Eosinophil Migration Across Monolayers of Lung Epithelial Cells: Eosinophil Chemoattractant and Priming Agent and Epithelial Cell Activator

Infiltration of eosinophils into the lung lumen is a hallmark of allergic asthmatic inflammation. To reach the lung lumen, eosinophils must migrate across the vascular endothelium, through the interstitial matrix, and across the lung epithelium. The regulation of this process is obscure. In this study, we investigated the migration of human eosinophils across confluent monolayers of either human lung H292 epithelial cells or primary human bronchial epithelial cells. Established eosinophil chemoattractants (IL-8, RANTES, platelet-activating factor (PAF), leukotriene B4, and complement fragment 5a (C5a)) or activation of the epithelial cells with IL-1β induced little eosinophil transmigration (&lt;7% in 2 h). In contrast, addition of PAF in combination with C5a induced extensive (&gt;20%) transepithelial migration of unprimed and IL-5-primed eosinophils. Eosinophil migration assessed in a Boyden chamber assay, i.e., without an epithelial monolayer, was only slightly increased upon addition of PAF and C5a. Preincubation of eosinophils with the PAF receptor antagonist WEB 2086 only inhibited migration of unprimed eosinophils toward PAF and C5a, whereas preincubation of epithelial cells with WEB 2086 abolished migration of both IL-5-primed and unprimed eosinophils. This latter result indicated the presence of PAF receptors on epithelial cells. Indeed, addition of PAF to epithelial cells induced an increase in cytosolic free Ca2+, which was blocked by the PAF receptor antagonists WEB 2086 and TCV-309. Our results show that PAF induces permissive changes in epithelial cells, and that PAF acts as a chemoattractant and priming agent for the eosinophils.

Pharmacological studies on the novel antiallergic drug HQL-79: I. Antiallergic and antiasthmatic effects in various experimental models

The effects of oral administration of 4-benzhydryloxy-1-[3-(1H-tetrazol-5-yl)-propyl]piperidine (HQL-79), a newly synthesized antiallergic drug, in various experimental allergic and asthmatic models were investigated. HQL-79 markedly inhibited immediate hypersensitivity reactions such as passive cutaneous anaphylaxis in rats, antigen-induced bronchoconstriction and nasal vascular permeability in actively sensitized guinea pigs, like epinastine and ketotifen did. Airway eosinophilia in repeatedly antigen-exposed guinea pigs was suppressed by chronic administration of HQL-79 for 2 weeks. In another experiment, the antigen-induced late asthmatic response (LAR) in metyrapone-treated guinea pigs was also ameliorated by chronic treatment with HQL-79. Moreover, HQL-79 partially inhibited the toluene diisocyanate-induced delayed-type hypersensitivity (DTH) reaction in mice when administered chronically during the immunization period. The corticosteroid dexamethasone inhibited the airway inflammatory responses in guinea pigs and the DTH in mice. These results indicate that HQL-79 has potent inhibitory effects on the immediate hypersensitivity reactions, and when administered chronically, it also inhibits airway eosinophilia, LAR and DTH, similarly to corticosteroids.

Correlation among urinary eosinophil protein X, leukotriene E4, and 11-dehydrothromboxane B2 in patients with spontaneous asthmatic attack

Various kinds of cells and their mediators are thought to be involved in the pathogenesis of bronchial asthma. However, changes in each mediator or relationship among mediators during an asthmatic attack have not been well documented. In this study, to clarify whether eosinophil protein X (EPX) is a marker which is distinct from leukotriene E4 (LTE4), or 11-dehydrothromboxane B2 (11DTXB2), we measured the urinary excretion of EPX, LTE4, and 11DTXB2 in 14 asthmatics who were admitted to the hospital with either an acute asthmatic attack or status asthmaticus. These patients included eight atopic and six non-atopic types of bronchial asthma, with a median age of 34.0 years. Urinary excretion of EPX was significantly high on admission with the asthmatic attack, and returned to control levels 175 [122 -384] microg/day when the patients were in the improved state (1036-317 microg/day, P < 0.01). Similar findings were observed in LTE4 (155-59 ng/day, P < 0.01) and 11DTXB2 (991-442ng/day, P<0.01). No significant differences in values were observed between atopic and non-atopic types of asthma in all three substances. When the individual data during the attack state were analysed, a significant correlation was observed between changes (%) in urinary EPX and those in urinary LTE4, but no such relationship was observed between changes (%) in urinary EPX and those in urinary 11DTXB2. These results suggest that measuring urinary EPX levels may be a useful marker for the understanding and management of the disease.

Role of eosinophilic airway inflammation in models of asthma

Eosinophils play a central role in the establishment and outcome of bronchial inflammation in asthma. Animal models of allergy are useful to answer questions related to mechanisms of allergic inflammation. We have used models of sensitized and boosted guinea pigs to investigate the nature of bronchial inflammation in allergic conditions. These animals develop marked bronchial infiltration composed mainly of CD4+ T-lymphocytes and eosinophils. Further provocation with antigen leads to degranulation of eosinophils and ulceration of the bronchial mucosa. Eosinophils are the first cells to increase in numbers in the mucosa after antigen challenge and depend on the expression of alpha 4 integrin to adhere to the vascular endothelium and transmigrate to the mucosa. Blockage of alpha 4 integrin expression with specific antibody prevents not only the transmigration of eosinophils but also the development of bronchial hyperresponsiveness (BHR) to agonists in sensitized and challenged animals, clearly suggesting a role for this cell type in this altered functional state. Moreover, introduction of antibody against Major Basic Protein into the airways also prevents the development of BHR in similar model. BHR can also be suppressed by the use of FK506, an immunosuppressor that reduces in almost 100% the infiltration of eosinophils into the bronchi of allergic animals. These data support the concept that eosinophil is the most important pro-inflammatory factor in bronchial inflammation associated with allergy.

Inhibitory effect of pulmonary surfactant proteins A and D on allergen-induced lymphocyte proliferation and histamine release in children with asthma

The role of pulmonary surfactant proteins in the pathogenesis of airway inflammation and the impact on asthma has not been elucidated. This study was designed to examine the effect of surfactant proteins A (SP-A) and D (SP-D) on phytohemagglutinin- (PHA) and mite allergen Dermatophagoides pteronyssinus (Der p)-induced histamine release and the proliferation of peripheral blood mononuclear cells (PBMC) in children with asthma in stable condition (n = 21), asthmatic children during acute attacks (n = 9), and age-matched control subjects (n = 7). The results show that SP-A and SP-D were able to reduce the incorporation of [3H]thymidine into PBMC in a dose-dependent manner. In addition to the intact, native SP-A and SP-D proteins, a recombinant peptide composed of the neck and carbohydrate recognition domain (CRD) of SP-D [SP-D(N/CRD)] was also found to have the same suppressive effect on lymphocyte proliferation. This effect was abolished by the presence of 100 mM mannose (for SP-A) or maltose (for SP-D) in the culture medium, which suggested that the CRD regions of SP-A and SP-D may interact with the carbohydrate structures on the surface molecules of lymphocytes. The inhibitory effects of surfactant proteins on PHA- and Der p-stimulated lymphocyte responses were observed in stable asthmatic children and age-matched control subjects, while only a mild suppression (< 25%) was seen in activated lymphocytes derived from asthmatic children with acute attacks. SP-A and SP-D were also found to inhibit allergen-induced histamine release, in a dose-dependent manner, in the diluted whole blood of asthmatic children. We conclude that both SP-A and SP-D can inhibit histamine release in the early phase of allergen provocation and suppress lymphocyte proliferation in the late phase of bronchial inflammation, the two essential steps in the development of asthmatic symptoms. It appears that SP-A and SP-D may be protective against the pathogenesis of asthma.

Peak flow variability and sputum eosinophilia in allergic rhinitis

BACKGROUND

Although some non-asthmatic subjects with allergic rhinitis exhibit airway hyperresponsiveness and increased diurnal peak expiratory flow (PEF) variation, little is known about the critical features that determine these physiologic alterations.

OBJECTIVE

In subjects with allergic rhinitis and methacholine hyperresponsiveness but no asthma symptoms, we examined whether there were features of asthmatic airway inflammation.

METHODS

Forty non-asthmatic adults (11 with allergic rhinitis and methacholine hyperresponsiveness, 20 with allergic rhinitis and normal methacholine responsiveness, and 9 healthy control subjects) were studied. Sputum was induced with inhaled hypertonic saline for 5-minute periods for up to 20 minutes. Plugs from the lower respiratory tract were selected for differential counting in cytocentrifuged preparations. For the next 14 days, subjects measured their PEF two times daily. Peak expiratory flow variation was expressed as amplitude % mean.

RESULTS

Peak expiratory flow variation was significantly higher in subjects with allergic rhinitis and methacholine hyperresponsiveness than in allergic rhinitis patients with normal methacholine responsiveness and healthy controls. Eosinophil counts in the induced sputum were significantly higher in the subjects with allergic rhinitis and methacholine hyperresponsiveness [median (interquartile range), 7.3 (9.0)%] compared with allergic rhinitis patients with normal methacholine responsiveness [2.5 (3.8)%, P = .03] and healthy controls [1.0 (1.0)%, P = .02].

CONCLUSION

We conclude that eosinophilic inflammation may be present in subjects with allergic rhinitis and airway hyperresponsiveness even when there are no symptoms of asthma. This could indicate that bronchial eosinophilia is insufficient to cause asthmatic symptoms.

Eosinophil and mast cell parameters in children with stable moderate asthma

Mast cells and eosinophils are important cells that contribute to the process of inflammation in asthma either by activating other cells or by secreting products which are potentially toxic to the respiratory epithelium. The influx of these cells in the airways and the secretion of toxic products by these cells is abrogated by inhaled corticosteroids.

METHODS

In a double blind randomised, placebo controlled, study in children with stable moderate asthma (N = 34, 15 children received fluticasone propionate (FP), an inhaled corticosteroid, and 19 children used a placebo), we investigated the influence of treatment with FP 100 microg b.d. on various parameters of inflammation: number of eosinophils, secretory products of eosinophils i.e. ECP and EDN (in serum and urine) and a secretory product of mast cells, histamine, which is determined as the compound to which histamine is converted and excreted by the human body: NT-methyl-histamine.

RESULTS

Previously we reported that lung function increased and bronchial hyperresponsiveness decreased in the 30 children that completed the study during treatment with FP. In these children we found that none of the laboratory parameters of inflammation changed significantly during treatment with either FP or placebo. However, the decrease in urinary EDN almost reached significance (P = 0.07).

CONCLUSIONS

Our results indicate that the number of eosinophils, serum ECP and EDN and urinary EDN as well as urinary NT-methyl-histamine do not reflect asthma disease activity in children with stable moderate asthma. Our data on urinary EDN warrant further study of the use of this parameter to monitor asthma in children.

Effects of fluticasone propionate and beclomethasone dipropionate on parameters of inflammation in peripheral blood of patients with asthma

Bronchial inflammation plays a central role in asthma. We investigated whether parameters of inflammation were increased in peripheral blood. Furthermore, we tested whether fluticasone propionate (FP), a new inhaled corticosteroid (ICS), and beclomethasone dipropionate (BDP) affected these parameters. FP 750 microg/day and BDP 1500 microg/day were compared in a randomized, crossover study consisting of two 6-week treatment periods, each preceded by a 3-week placebo period. Twenty-one patients with symptomatic asthma completed the study. The results were compared with those of six normal subjects (controls). Immunophenotyping of inflammatory cells was performed in whole blood, and serum eosinophil cationic protein (ECP) was measured. With regard to clinical efficacy, ICS increased PC20 histamine by more than 1.9 doubling doses and FEV1 by more than 0.34 l. The number of CD3/HLA-DR+ lymphocytes was significantly increased in asthmatics compared to the normal subjects, both after placebo (P<0.01) and after therapy (P<0.05). The CD3/HLA-DR+ lymphocytes decreased significantly after treatment with FP (P<0.05). Serum ECP was elevated in patients without ICS and decreased after treatment with BDP (P<0.001). In conclusion, the number of CD3/HLA-DR+ lymphocytes and serum ECP levels were raised in the peripheral blood of symptomatic asthmatics, and decreased by clinically effective doses of ICS. In this respect, FP 750 microg/day was at least as effective as BDP 1500 microg/day.

Inflammation, inflammatory mediators, and mediator antagonists in asthma

Asthma is an inflammatory disease that involves mast cells, antigen-presenting cells, eosinophils, neutrophils, and TH2-lymphocytes. These cells produce a broad array of mediators and cytokines that lead to the bronchoconstriction, mucosal edema, mucus secretion, and bronchial hyperresponsiveness that characterize asthma. Current guidelines for therapy recommend that all patients whose asthma is more severe than mild intermittent receive chronic treatment with drugs that interrupt this inflammatory cascade. Corticosteroids have been the gold standard for treatment, but a greater understanding of the specific cells and mediators involved in the pathogenesis of asthma has led to more focused, specific therapy. Pharmacologic agents that interrupt the synthesis of action of leukotrienes, and monoclonal antibodies directed against intracellular adhesion molecules or immunoglobulin E are examples of the new generation of specific targeted therapy for use in asthma.

Acetylcholine stimulates alveolar macrophages to release inflammatory cell chemotactic activity

Neurological transmitters including ACh, substance P (SP), and calcitonin gene-related peptide (CGRP) play an important role in regulating airway tone, and increased bronchial reactivity to cholinergic stimulation is a well-recognized phenomenon in patients with bronchial asthma. We postulated that ACh, SP, and CGRP might stimulate alveolar macrophages (AMs) to release neutrophil, monocyte, and eosinophil chemotactic activities. To test this hypothesis, bovine AMs were isolated by bronchoalveolar lavage and cultured. AMs released chemotactic activities in response to ACh in a dose- and time-dependent manner (P < 0.05). However, SP and CGRP did not stimulate bovine AMs. Checkerboard analysis revealed that these released activities were predominantly chemotactic. Partial characterization and molecular-sieve column chromatography revealed that low-molecular-weight lipid-soluble activity was predominant. Lipoxygenase inhibitors significantly blocked the release of chemotactic activities (P < 0.05). Leukotriene B4- and platelet-activating factor-receptor antagonists blocked the chemotactic activities. Immunoreactive leukotriene B4 significantly increased in supernatant fluids in response to ACh (P < 0.05), but platelet-activating factor did not. The receptor responsible for the release of the chemotactic activities was the muscarinic M3 receptor. These data demonstrate that ACh stimulates AMs to release lipoxygenase-derived chemotactic activities and plays a role in inflammatory cell recruitment into the airway.

Abrogation of bronchial eosinophilic inflammation and airway hyperreactivity in signal transducers and activators of transcription (STAT)6-deficient mice

Signal transducers and activators of transcription 6 (STAT6) is essential for interleukin 4-mediated responses, including class switching to IgE and induction of type 2 T helper cells. To investigate the role of STAT6 in allergic asthma in vivo, we developed a murine model of allergen-induced airway inflammation. Repeated exposure of actively immunized C57BL/6 mice to ovalbumin (OVA) aerosol increased the level of serum IgE, the number of eosinophils in bronchoalveolar lavage (BAL) fluid, and airway reactivity. Histological analysis revealed peribronchial inflammation with pulmonary eosinophilia in OVA-treated mice. In STAT6-deficient (STAT6-/-) C57BL/6 mice treated in the same fashion, there were no eosinophilia in BAL and significantly less peribronchial inflammation than in wild-type mice. Moreover STAT6-/- mice had much less airway reactivity than wild-type mice. These findings suggest that STAT6 plays a crucial role in the pathogenesis of allergen-induced airway inflammation.

A stability study involving HPLC analysis of aqueous thiorphan solutions in the presence of human serum albumin

The stability of thiorphan (1.0 mg/ml) in normal saline containing 1% human serum albumin (HSA) was determined in order to find the most appropriate storage conditions. Direct liquid chromatographic analysis of this solution was feasible through the use of a micellar chromatographic system and proved to be stability indicating. During 8 weeks the percentages of the initial thiorphan concentration remaining after storage at 4, 20, 30, and 50 degrees C were determined. An Arrhenius plot was composed using the rate constants of thiorphan degradation at these temperatures. The thiorphan solution was stable for at least 2 months if stored at -20 degrees C. Taking into account the oxidative degradation of about 7% after thawing, we determined that the solution can be kept in a refrigerator for 4 days. Storage at room temperature should be limited to 1 day. By identification of the degradation products it could be concluded that thiorphan is degraded mainly via oxidation forming disulfides. Therefore, it is recommended that the solvent be purged with nitrogen before thiorphan is dissolved.

Selective CD8+ T cells accumulate in the lungs of patients with allergic asthma after allergen bronchoprovocation

Our objective was to study whether CD4+ or CD8+ T cells expressing particular T cell receptors (TCR) would accumulate in the lungs of patients with allergic asthma following allergen exposure. We thus analysed the TCR Valpha and Vbeta gene usage of CD4+ and CD8+ lung and peripheral blood lymphocytes (PBL) of eight patients with allergic asthma before and 4 days after inhalation challenge with the relevant allergen. Lung cells obtained by bronchoalveolar lavage (BAL) and paired PBL samples were analysed by flow cytometry using a panel of anti-TCR V-specific monoclonal antibodies that encompass = 50% of the T cell repertoire. Lung-limited T cell expansions were recorded in both the CD4+ and the CD8+ subsets. In BAL CD8+, out of a total of 126 analyses, the number of T cell expansions increased from two to 11 after challenge, some of them dramatic. In BAL CD4+ the frequency of expansions was moderately increased already before challenge, but remained unchanged. A few expansions that tended to persist were noted in PBL CD8+. When analysing the overall change in TCR V gene usage the largest changes were also recorded in the BAL CD8+ subset. Specific interactions between T cells and antigens may lead to an increased frequency of T cells using selected TCR V gene segments. In this study we demonstrate that following allergen bronchoprovocation in allergic asthmatic subjects, T cell expansions preferentially emerge in the lung CD8+ T cell subset.

Perception of the role and potential side effects of inhaled corticosteroids among asthmatic patients

BACKGROUND

Misunderstanding of the role of asthma medication and fear of untoward side effects may reduce compliance to therapy, potentially resulting in poor asthma control and increased risk of severe asthma events.

METHODS

We report the results of a recent Canadian survey of 603 asthmatic patients recruited from the general population, aimed at determining their perception of the role and potential side effects of inhaled corticosteroids (ICS).

RESULTS

The survey revealed that a large proportion of asthmatic patients do not understand the role of their medications and have many misconceptions and fears in regard to ICS, reducing their willingness to use them. Among the most common fears are those concerning troublesome side effects, particularly in regard to corporeal image, bone density, and a reduction in efficacy of medication over time. More than half of the population said they were very or somewhat concerned using ICS on a regular basis; two thirds of patients had not discussed their concerns about ICS with their physicians or other health-care professionals. Finally, in a large number of asthma patients, asthma was not adequately controlled, according to recent asthma consensus guidelines.

CONCLUSIONS

These observations stress the importance for those involved in asthma care of questioning patients about their understanding of the role of asthma medications, particularly ICS, their fears and misconceptions, and what they consider to be adequate asthma control, in order to provide appropriate education and counseling.

Molecular basis of allergic diseases

This review examines our current understanding of the mechanisms underlying allergic diseases. The IgE molecule plays a central role in the pathogenesis of immediate hypersensitivity reactions by virtue of its capacity to bind specifically to high-affinity IgE receptors on mast cells and mediate the release of various mast cell-derived mediators and proinflammatory cytokines on exposure to allergen. Clinically significant allergic responses are followed by a late-phase response dominated by eosinophils and T lymphocytes. The majority of T cells in allergic responses are memory T cells secreting helper type 2 (TH2)-like cytokines, i.e., interleukin (IL)-4, IL-5, IL-13, but not interferon-gamma. These cytokines regulate IgE synthesis and promote eosinophil development, thus contributing to allergic inflammatory responses. Failure to control immune activation early in the course of allergic disease blunts responses to glucocorticoid therapy and contributes to disease progression. The identification of key cells and molecules involved in the initiation and maintenance of allergic inflammation is likely to become an important target in the treatment of this common group of illnesses.

A study of granulocyte respiratory burst in patients with allergic bronchial asthma

The respiratory burst of phagocytes plays an important role in the tissue damage that accompanies the inflammatory response. One of these conditions is allergic bronchial asthma, therefore, to evaluate the activation state of peripheral granulocytes the generation of reactive oxygen metabolites was evaluated using Luminol-enhanced chemiluminescence (LCL) and reduction of cytochrome C by superoxide. The resting granulocytes of the asthmatic patients under crisis showed a higher LCL compared to the noncrisis patients and control subjects. The granulocytes stimulated with PMA presented a significant increase in the respiratory burst in both groups of asthmatics. The granulocytes of noncrisis asthmatics challenged with Ops-Zym and with fMLP + Ops-Zym showed a higher metabolic activity, whereas the asthmatics under crisis presented no difference between reactive oxygen generation and that of the control group. The quantitative analysis of superoxide generation by granulocytes of the same patients did not show differences among the groups. Our findings suggest that the granulocytes of crisis and noncrisis asthmatics seem to be in a hyperreactive state and with a higher metabolic response when compared to the control group. However, the patients present a different behavior depending on stimulus used to activate cells. This could indicate that in peripheral blood exist different granulocyte populations depending on the inflammatory response taking place in the respiratory tract.

Induction of Pulmonary Allergic Responses by Antigen-Specific Th2 Cells

The development of pulmonary allergic responses was examined in mice following pulmonary transfer of Ag (conalbumin)-specific Th2 cells. The levels of serum-specific IgE, cellular infiltrates, airway mucus goblet cells, and airway responsiveness were analyzed and compared with those in Ag-sensitized and -challenged mice. Pulmonary transfer of the conalbumin-specific Th2 clone (D10) induced, in an Ag-specific manner, high levels of the Th2 cytokines IL-4 and IL-5 in the bronchoalveolar lavage fluids and mucosal eosinophils, concomitant with an increase in airway responsiveness. The D10 cell-induced responses were seen in the absence of serum specific IgE. In the presence of Ag, the transferred D10 cells not only remained in the lungs, but also increased in number 72 h post-cell transfer. Although significantly higher levels of IL-4 and IL-5 in the bronchoalveolar lavage fluids were found in D10-transferred mice, the levels of pulmonary eosinophilia, mucus goblet cells, and airway responsiveness were significantly lower than those in Ag-sensitized and -challenged mice. These results demonstrate that although Ag-specific activation of Th2 cells at mucosal sites is able to mediate the recruitment of eosinophils and the subsequent induction of airway hyper-responsiveness, the more severe pulmonary allergic responses were observed only in mice sensitized and challenged with Ag.

Variability of peak expiratory flow rate in allergic rhinitis and mild asthma: relationship to maximal airway narrowing

BACKGROUND

Previous studies have demonstrated a significant correlation between airway sensitivity to pharmacologic agents and daily peak expiratory flow rate (PEF) variation in asthmatic and nonasthmatic subjects.

OBJECTIVE

The aim of this study was to investigate, both in patients with asthma and in subjects with allergic rhinitis, differences in daily PEF variation between subjects with plateau on the concentration-response curves to methacholine and those without plateau.

METHODS

A total of 120 adults (50 with mild asthma, 52 with allergic rhinitis, and 18 healthy control subjects) were challenged with methacholine (up to 200 mg/mL) and, for the next 14 days, measured their PEF three times daily. The response to methacholine was measured by the percent decrease in FEV1. A maximal response plateau was considered if three or more of the highest concentrations fell within a 5% response range. Diurnal PEF variation was expressed as the amplitude percent mean.

RESULTS

A plateau response was detected in 11 (22%) asthmatic patients, in 33 (63%) subjects with allergic rhinitis, and in 17 (94%) healthy subjects. Diurnal PEF variation was significantly greater (P < .01) in the asthmatic group without a plateau (8.8 +/- 3.7%) compared with the three groups with a plateau (asthma = 5.5 +/- 2.9%; allergic rhinitis = 4.6 +/- 2.1%; healthy = 4.7 +/- 2.3%). Those three groups with a plateau were not significantly different from each other with respect to PEF variability. Diurnal PEF variation was significantly higher in allergic rhinitis patients without plateau (7.6 +/- 3.5%) than in allergic rhinitis patients with plateau (P < .01) and healthy subjects (P < .05). The rhinitic group without a plateau, however, was not significantly different from either the asthmatic group without plateau or the asthmatic group with plateau.

CONCLUSIONS

We conclude that in both asthmatic patients and subjects with allergic rhinitis, the shape of the concentration-response curve to methacholine provides new information on the relationship between airway responsiveness and PEF variability. Further, allergic rhinitis subjects without evidence of plateau have a degree of diurnal PEF variation similar to that found in patients with mild asthma. This could indicate that those subjects may have subclinical inflammatory changes in the airways.

New insights into steroid resistant asthma

The term "steroid resistant (SR) asthma" refers to a group of asthmatics who have persistent airway obstruction and immune activation despite treatment with high doses of systemic glucocorticoids. There are at least two forms of SR asthma, i.e. primary and acquired types. Type I SR asthma is acquired and is associated with abnormally reduced glucocorticoid receptor (GCR) ligand and DNA binding affinity. Type II SR asthma appears to be due to a constitutive defect and is associated with low numbers of GCRs. An important distinction between these two types of SR asthma is that the GCR defect in Type I, but not Type II, SR asthma is reversible in culture and is sustained by incubation with combination IL-2 and IL-4. Recent studies suggest that the abnormal GCR binding in Type I SR asthma may be due to cytokine-driven alternative splicing of the GCR pre-mRNA to a novel isoform called GCRbeta which does not bind glucocorticoids but antagonizes the transactivating activity of the classic GCR. These GCR changes along with recent evidence for increased transcription factor activation in SR asthma which may inhibit GCR/DNA interactions as well as the selective recruitment of neutrophils into the airways of certain patients with severe asthma contribute to the heterogeneity of mechanisms underlying steroid resistance.

Ozone affects breathing and pulmonary surfactant function in mice

The effect on breathing of BALB/c mice immediately following ozone exposure (2 ppm) for 0, 2, 4, 6, and 8 h was studied with a whole body plethysmograph. Whether such exposure affected the normal function of pulmonary surfactant of maintaining airway patency was evaluated with a capillary surfactometer. Respiratory rate in mice that were not exposed was 358+/-16 (mean+/-S.E.) breaths/min and decreased to 202+/-10 after 6 h exposure. The mean pressure change caused by breathing diminished significantly, indicating a reduced tidal volume. BAL fluid from controls maintained patency for 88+/-2% of the study time, 120 s, implying a good surfactant function, but the ozone exposure caused the surfactant to lose its capability of maintaining patency (P < 0.0001). This decaying surfactant function of the BAL fluid coincided with an increasing protein concentration in the fluid of exposed animals (1.46+/-0.14 mg/ml in the 8-h group) as compared to controls (0.44+/-0.04 mg/ml, P < 0.0001). It is concluded that leakage of plasma proteins into the airway lumen was probably the main reason for the surfactant dysfunction, which may have contributed to the altered breathing pattern.

Immunopathologic responses to Aspergillus antigen in interleukin-4 knockout mice

Two strains of interleukin-4 (IL-4) gene knockout mice were studied and compared with wild strains to determine the role of IL-4 in the immunopathogenesis of murine allergic aspergillosis. Animals immunized intraperitoneally were subsequently challenged with Aspergillus antigen intranasally. The animals were evaluated for total serum immunoglobulin E (IgE) levels, Aspergillus-specific IgG antibody isotypes, peripheral blood eosinophils, cytokine and chemokine mRNA transcripts in spleen cells, and pulmonary histology. No serum IgE was detected in animals deficient in the IL-4 gene. Aspergillus-specific IgG1 was detected in all animals, while enhanced levels of IgG2a were detected in IL-4 knockout animals challenged with A. fumigatus antigen. There were no differences in the peripheral blood or lung eosinophils in the two groups of mice exposed to A. fumigatus. These results indicate that lung injury in Aspergillus-antigen challenged animals may be the result of the eosinophil mediators and that IgE-mediated injury may not be significant in this model, which may be a significant variation between the model and human allergic aspergillosis.

Polymorphonuclear leukocytes from asthmatics release more calcium from intracellular stores and have enhanced calcium increase after stimulation with N-formyl-methionyl-leucyl-phenylalanine

Polymorphonuclear leukocytes isolated from peripheral blood of asthmatics appear to be primed to release more reactive oxygen species than cells of healthy subjects. The enhanced agonist-induced rise in the intracellular free calcium concentration may be responsible for this increased respiratory burst. To test this hypothesis we studied the N-formyl-methionyl-leucyl-phenylalanine- and cyclopiazonic acid--(an inhibitor of Ca(2+)-ATPase of intracellular calcium stores) induced calcium increase in the polymorphonuclear leukocytes of 28 subjects (16 with moderate asthma, 69.6% +/- 8.3% predicted normal peak expiratory flow and 12 normal controls) using a fluorescent probe Fura-2AM at 100 nM and 1 mM extracellular calcium concentrations. In 1 mN calcium, the N-formyl-methionyl-leucyl-phenylalanine-induced calcium increase was 1.7-fold higher in asthmatics than in healthy subjects. Similarly, the contribution of calcium from intracellular stores to the calcium response to N-formyl-methionyl-leucyl-phenylalanine was higher in asthmatics (55% +/- 14% vs. 39% +/- 14%, P < 0.01). The pool of calcium released from intracellular stores by N-formyl-methinoyl-leucyl-phenylalanine and cyclopiazonic acid was 2.3- and 2.2-fold larger than in control cells. There was a correlation between maximal intracellular calcium concentration related to N-formyl-methionyl-leucyl-phenylalanine-induced calcium release from intracellular stores and forced expiratory volume in 1 s expressed as percentage predicted and reversibility in asthmatics (r = 0.63, r = -0.53, P < 0.05). In conclusion, polymorphonuclear leukocytes of asthmatics exhibit an altered calcium response that is mainly dependent on increased calcium release from intracellular stores.

Immunologic basis of chronic allergic diseases: clinical messages from the laboratory bench

During the past decade there have been significant advances in our understanding of the mechanisms underlying allergic responses. Immediate hypersensitivity reactions are mediated primarily by mast cells in an IgE-dependent manner. After the local release of various mediators, proinflammatory cytokines, and chemokines, there is a cell-mediated response that is dominated by eosinophils and T lymphocytes. The majority of T cells in early allergic reactions are memory T cells secreting helper type 2 (TH2)-like cytokines, i.e. IL-4, IL-5, and IL-13, but not interferon-gamma. These cytokines regulate IgE synthesis and promote eosinophil differentiation and cell survival, thus contributing to allergic inflammatory responses. Failure to control immune activation early in the course of allergic inflammation may blunt the response to glucocorticoid therapy and contribute to long-term morbidity of disease. The identification of key cells and cytokines involved in the initiation and maintenance of allergic inflammation is likely to become an important therapeutic target in the future management of this important group of diseases.

Interleukin-4 alters epithelial cell differentiation and surfactant homeostasis in the postnatal mouse lung

Interleukin-4 (IL-4) is a pleotrophic cytokine which is increased during lung injury and inflammation. Epithelial cell morphology and surfactant homeostasis were assessed in 4-52-wk-old transgenic mice in which IL-4 was expressed in the bronchial and bronchiolar epithelial cells under the control of the Clara cell secretory protein promoter (CCSP-IL-4 mice). IL-4 caused progressive pulmonary infiltration with macrophages, lymphocytes, neutrophils, and eosinophils. Epithelial cell hypertrophy and mucus cell metaplasia were observed in the lungs of CCSP-IL-4 mice at all ages. Airway epithelial cells contained increased neutral glycoproteins and expressed gastric mucin, normally absent in the bronchiolar epithelium of the mouse. Immunohistochemical and biochemical studies demonstrated increased surfactant proteins A and B in lung sections and lung homogenates of CCSP-IL-4 transgenic mice. Increased immunostaining for surfactant proprotein C was also detected in type II epithelial cells of the transgenic mice. In contrast, surfactant protein B and CCSP expression was decreased or was absent in hypertrophic epithelial cells lining the conducting airways of transgenic mice. Lung-specific increase in T-cell proliferative responses to mitogenic stimulation and antibody secretion were detected in CCSP-IL-4 mice. Differentiated characteristics of respiratory epithelial cells were dramatically influenced by the chronic production of IL-4 in the conducting airways. Alterations in lung morphology in the CCSP-IL-4 mice are similar to some of those induced by antigenic stimulation or associated with chronic airway inflammation.