Asthma, inflammation, eosinophils and bronchial hyperresponsiveness

Digital Image Comparison of Cellular Yield in Bronchial Brushing: Pre- and Post-Biopsy Lavage Cytology

INTRODUCTION

Bronchoscopy is a useful diagnostic tool capable of performing core biopsy, forceps biopsy, bronchoalveolar lavage, and bronchial brushing. This study compares the cellularity of bronchial cytology including pre- and post-biopsy lavage by digital image analysis, aiming to increase diagnostic and tumor yield by optimizing the sequence and combination of bronchial biopsy and cytology.

METHODS

Alveolar macrophage, bronchial epithelium, and tumor cell cellularity from liquid-based cytology preparations of bronchial brushing and pre-biopsy and post-biopsy bronchoalveolar lavage were annotated on digitized whole-slide images and compared. Secondary analysis on the relationship of tumor cell and non-lesional cell yield was performed.

RESULTS

Overall, 118 cytology specimens from 43 patients were retrieved in total. Bronchial epithelium count was higher in pre-biopsy than post-biopsy lavage (p < 0.01) but not for alveolar macrophages nor tumor cell (p > 0.05). Tumor cell count was higher for bronchial brushing cytology samples than lavage (p = 0.018). The alveolar macrophage count was higher in post-biopsy lavage than bronchial brushing (p = 0.033); otherwise, brushing showed consistently higher bronchial epithelium and tumor cell counts. There were 33 false negative (tumor cell absent) specimens, and the combination of bronchial brushing and pre-biopsy lavage yielded the lowest false negative cases. Correlation between bronchial epithelium and alveolar macrophage counts with tumor cell count was weak (correlation coefficient = -0.168-0.203) except for post-biopsy lavage (correlation coefficient = 0.412-0.479, p < 0.05).

CONCLUSION

Bronchial brushing yields a greater amount of tumor cell than lavage, and timing lavage before or after core biopsy does not affect tumor cell yield. Combining bronchial brushing and pre-biopsy lavage results in the lowest false negative rate.

Targeting the RhoA-GEF-H1 pathway of mast cells attenuates experimental airway allergy

Mast cells are the major effector cells in allergic diseases. RhoA and its downstream pathway is associated with the pathogenesis of airway allergy. The objective of this study is to test a hypothesis that modulating the RhoA-GEF-H1 axis in mast cells can attenuate airway allergy. An airway allergic disorder (AAD) mouse model was employed. Mast cells were isolated from AAD mouse airway tissues to be analyzed by RNA sequencing. We observed that mast cells isolated from the respiratory tract of AAD mice were resistant to apoptosis. Mast cell mediator levels in nasal lavage fluid were correlated with apoptosis resistance in AAD mice. Activation of RhoA in AAD mast cells was related to resistance to apoptosis. Mast cells isolated from the airway tissues in AAD mouse exhibited strong RhoA-GEF-H1 expression. The RhoA-GEF-H1 axis was associated with the lower FasL expression in AAD mast cells. Activation of the RhoA-GEF-H1 axis promoted the production of mediators in mast cells. Inhibition of GEF-H1 facilitated the SIT-induced mast cell apoptosis and enhanced the therapeutic efficacy of AAD. In conclusion, RhoA-GEF-H1 activities are associated with resistance to apoptosis in mast cells isolated from sites of allergic lesions. The state of apoptosis resistance in mast cells is associated with the state of AAD disease. Inhibition of GEF-H1 restores the sensitivity of mast cells to apoptosis inducers, and alleviates experimental AAD in mice.

The PPARγ agonist, rosiglitazone, attenuates airway inflammation and remodeling via heme oxygenase-1 in murine model of asthma

AIM

Rosiglitazone is one of the specific PPARγ agonists showing potential therapeutic effects in asthma. Though PPARγ activation was considered protective in inhibiting airway inflammation and remodeling in asthma, the specific mechanisms are still unclear. This study was aimed to investigate whether heme oxygenase-1 (HO-1) related pathways were involved in rosiglitazone-activated PPARγ signaling in asthma treatment.

METHODS

Asthma was induced in mice by multiple exposures to ovalbumin (OVA) in 8 weeks. Prior to every OVA challenge, the mice received rosiglitazone (5 mg/kg, p.o.). After the mice were sacrificed, the bronchoalveolar lavage fluid (BALF), blood samples and lungs were collected for analyses. The activities of HO-1, MMP-2 and MMP-9 in airway tissue were assessed, and the expression of PPARγ, HO-1 and p21 proteins was also examined.

RESULTS

Rosiglitazone administration significantly attenuated airway inflammation and remodeling in mice with OVA-induced asthma, which were evidenced by decreased counts of total cells, eosinophils and neutrophils, and decreased levels of IL-5 and IL-13 in BALF, and by decreased airway smooth muscle layer thickness and reduced airway collagen deposition. Furthermore, rosiglitazone administration significantly increased PPARγ, HO-1 and p21 expression and HO-1 activity, decreased MMP-2 and MMP-9 activities in airway tissue. All the therapeutic effects of rosiglitazone were significantly impaired by co-administration of the HO-1 inhibitor ZnPP.

CONCLUSION

Rosiglitazone effectively attenuates airway inflammation and remodeling in OVA-induced asthma of mice by activating PPARγ/HO-1 signaling pathway.

Innate lymphoid cells and cytokines of the novel subtypes of helper T cells in asthma

BACKGROUND

In this study, the expression of interleukin-9 (IL-9), IL-17, IL-22, and IL-25 genes that might be the potential predisposing factors for asthma as well as count of innate lymphoid cells (ILCs) as another source of inflammatory cytokines have been evaluated.

OBJECTIVE

The aim of this study was to evaluate the expression of newly identified helper T cells signature cytokines and amount of ILCs.

METHODS

Blood and sputum samples from 23 patients with moderate to severe asthma and 23 healthy volunteers were collected. The types of allergens to which our patients were sensitive were defined using immunoblotting method. Gene expression of studied cytokines was evaluated using quantitative transcription-polymerase chain reaction and ILCs were counted by the flow cytometry method.

RESULTS

In this research, the gene expressions of IL-9, IL-17, IL-22, and IL-25 were significantly higher in asthmatics, especially in the severe form of the disease. This increase was even higher in serum samples compared with sputum samples. Counting ILCs revealed their increase in comparison with normal people.

CONCLUSION

We showed the importance of IL-25, IL-22, IL-17, and IL-9 cytokines in patients with asthma as their expression levels are increased and these increase are correlated with the severity of the disease. We also showed that the increased amount of ILCs in asthmatics could confirm their potential role in the immunopathogenesis of asthma as another source of inflammatory cytokines.

New routes for allergen immunotherapy

IgE-mediated allergy is a highly prevalent disease in the industrialized world. Allergen-specific immunotherapy (SIT) should be the preferred treatment, as it has long lasting protective effects and can stop the progression of the disease. However, few allergic patients choose to undergo SIT, due to the long treatment time and potential allergic adverse events. Since the beneficial effects of SIT are mediated by antigen presenting cells inducing Th1, Treg and antibody responses, whereas the adverse events are caused by mast cells and basophils, the therapeutic window of SIT may be widened by targeting tissues rich in antigen presenting cells. Lymph nodes and the epidermis contain high density of dendritic cells and low numbers of mast cells and basophils. The epidermis has the added benefit of not being vascularised thereby reducing the chances of anaphylactic shock due to leakage of allergen. Hence, both these tissues represent highly promising routes for SIT and are the focus of discussion in this review.

TNF-induced IL-8 and MCP-1 production in the eosinophilic cell line, EOL-1

The role of eosinophils in inflammation and their mode of activation is not well understood. Eosinophil accumulation and subsequent expression of cytokines at the site of inflammation may play a role in exacerbation of inflammatory responses. In the present study, we have examined the role of TNF-α in eosinophil activation and chemokine production using a human leukaemic eosinophil cell line, EOL-1. Initial studies demonstrated that TNF-α induced the upregulation of IL-8 and MCP-1 mRNA and protein. Kinetic studies indicated production of chemokines, IL-8 and MCP-1, as early as 4 h post-activation, with peak levels of chemokine produced at 8 h, and decreasing by 24 h post-TNF-α activation. When IL-10, a suppressive cytokine, was incubated with TNF-α and EOL-1 cells, no effect was observed on IL-8 and MCP-1 production. However, dexamethasone, a glucocorticoid, demonstrated potent inhibitory effects on the EOL-1-derived chemokines. These studies indicate that eosinophils may be a significant source of chemokines capable of participating in, and maintaining, leukocyte recruitment during inflammatory responses, such as asthma.

Response to oyster mushroom (Pleurotus ostreatus) extract by sensitized and nonsensitized guinea pig trachea

Occupational exposure to oyster mushroom (Pleurotus ostreatus) has been associated with obstructive lung disease. Previously, we studied an extract of oyster mushroom (OME) and determined that it causes dose-dependent contractions of nonsensitized guinea pig trachea (GPT). We extend these studies to the investigation of sensitized tissue. In the present study 24 animals were sensitized using ovalbumin (OA) and subsequently challenged with an aerosol of 2.5% OA. A control group of 12 nonsensitized GPs was also studied. Tracheas were removed and were divided into rings in which the epithelium was retained (EP+) or removed (EP-). Dose-related contractions of sensitized and nonsensitized GPTs were elicited with OME. In nonsensitized animals the EP+ GPTs demonstrated a significantly greater response to OME (100-1000 μl) than did the EP- GPTs (p < 0.01). By contrast, in sensitized GPTs with and without epithelium there was no difference to challenge with OME. Finally, sensitized GPTs with and without epithelium and nonsensitized GPTs with epithelium responded similarly to challenge with OME. These findings suggest that in nonsensitized animals there is an enhancement of contractile response to OME which is in part mediated by the GPT epithelium. In sensitized animals with or without epithelium, the level of bronchoconstrictor response is similar to that of the nonsensitized animals with epithelium, suggesting an enhanced constrictor response independent of epithelium in the sensitized animals.

Fractional exhaled nitric oxide in asthma: an update

In asthma, clinical symptoms and lung function are insensitive in reflecting the underlying airway inflammation, and monitoring of this process has only recently become available. Fractional exhaled nitric oxide (Fe(NO)) is now recognized as a reliable surrogate marker of eosinophilic airway inflammation and offers the advantage of being completely non-invasive and very easy to obtain. This review summarizes the clinical use of Fe(NO) in asthma. It covers the relationship between Fe(NO) and the underlying eosinophilic inflammation, the pathophysiology and production of Fe(NO), technical aspects of Fe(NO) measurement and potential confounding factors in interpreting levels. Fe(NO) reference values and the role of Fe(NO) in asthma assessment, diagnosis and management are also discussed.

Comparison of histochemical methods for murine eosinophil detection in an RSV vaccine-enhanced inflammation model

A comparative study of histochemical detection of eosinophils in fixed murine tissue is lacking. Five histochemical methods previously reported for eosinophil detection were quantitatively and qualitatively compared in an established murine RSV vaccine-enhanced inflammation model. Nonspecific neutrophil staining was evaluated in tissue sections of neutrophilic soft tissue lesions and bone marrow from respective animals. Eosinophils had granular red to orange-red cytoplasmic staining, depending on the method, whereas neutrophils had, when stained, a more homogenous cytoplasmic pattern. Nonspecific background staining of similar coloration was variably seen in vascular walls and erythrocytes. Astra Blue/Vital New Red, Congo Red, Luna, Modified Hematoxylin and Eosin, and Sirius Red techniques were all effective in detecting increased eosinophil recruitment compared to controls; however, differences in eosinophil quantification varied significantly between techniques. Astra Blue/Vital New Red had the best specificity for differentiating eosinophils and neutrophils but had a reduced ability to enumerate eosinophils and was the most time intensive. The Luna stain had excessive nonspecific staining of tissues and a reduced enumeration of infiltrating eosinophils, which made it suboptimal. For multiple parameters such as eosinophil detection, specificity, and contrast with background tissues, the Sirius Red followed by Congo Red and Modified Hematoxylin and Eosin methods were useful, each with their own staining qualities.

Asthma

Asthma has been recognized as a disease since the earliest times. In the Corpus Hippocraticum, Hippocrates used the term “ασθμα” to indicate any form of breathing difficulty manifesting itself by panting. Aretaeus of Cappadocia, a well-known Greek physician (second century A.D.), is credited with providing the first detailed description of an asthma attack [13], and to Celsus it was a disease with wheezing and noisy, violent breathing. In the history of Rome, we find many members of the Julio-Claudian family affected with probable atopic respiratory disorders: Caesar Augustus suffered from bronchoconstriction, seasonal rhinitis as well as a highly pruritic skin disease. Claudius suffered from rhinoconjunctivitis and Britannicus was allergic to horse dander [529]. Maimonides (1136–1204) warned that to neglect treatment of asthma could prove fatal, whereas until the 19th century, European scholars defined it as “nervous asthma,” a term that was given to mean a defect of conductivity of the ninth pair of cranial nerves.

Methods and application areas of endoscopic optical coherence tomography

We review the current state of research in endoscopic optical coherence tomography (OCT). We first survey the range of available endoscopic optical imaging techniques. We then discuss the various OCT-based endoscopic methods that have thus far been developed. We compare the different endoscopic OCT methods in terms of their scan performance. Next, we examine the application range of endoscopic OCT methods. In particular, we look at the reported utility of the methods in digestive, intravascular, respiratory, urinary and reproductive systems. We highlight two additional applications--biopsy procedures and neurosurgery--where sufficiently compact OCT-based endoscopes can have significant clinical impacts.

Sputum eosinophil counts and eosinophil cationic protein levels in cough-variant asthma and in classic asthma, and their relationships to airway hypersensitivity or maximal airway response to methacholine

BACKGROUND

The aims of this study were to compare the degree of airway inflammation in cough-variant asthma (CVA) with that in classic asthma (CA), and to examine the relationship between airway inflammation and airway hypersensitivity or maximal airway response to methacholine in both conditions.

METHODS

Sputum was induced in 41 CVA patients, in 41 methacholine PC(20)-matched CA patients, and in 20 healthy children. The sputum samples were analyzed for total and differential cell counts, and for eosinophilic cationic protein (ECP). A high-dose methacholine challenge test was performed in CVA and CA patients to determine PC(20) and maximal airway response.

RESULTS

Sputum eosinophil percentages and ECP levels were significantly elevated in CVA and CA vs the control, but no significant differences were found between the two asthma groups. In the two asthma groups, neither sputum parameters correlated significantly with methacholine PC(20). However, the absence of a maximal response plateau or its higher level, when present, was associated with increased eosinophil percentages and ECP levels in the CVA group.

CONCLUSIONS

The degree of eosinophilic inflammation may not be causally related to differences in presented asthma manifestations. The identification of a maximal response plateau and the level of this plateau in patients with CVA may provide information pertinent to airway eosinophilic inflammation.

Overlapping and independent contributions of MMP2 and MMP9 to lung allergic inflammatory cell egression through decreased CC chemokines

The mechanisms that initiate allergic lung inflammation are relevant to expression of diseases such as asthma, but the factors underlying resolution of inflammation are equally important. Previously, we demonstrated the importance of matrix metalloproteinase 2 (MMP2) for airway egression of lung eosinophils, a critical anti-inflammatory mechanism without which mice are rendered highly susceptible to lethal asphyxiation. Here we show that leukocyte MMP9 is the dominant airway MMP controlling inflammatory cell egression. The allergic lung phenotype of MMP9-/- mice was similar to WT and was not altered by concomitant deletion of the MMP2 gene (double knockout; dko). However, inflammatory cells accumulated aberrantly in the lungs of allergen-challenged MMP9-/- and dko mice and fewer eosinophils and neutrophils were present in bronchoalveolar lavage. These aberrant cellular trafficking patterns were explained by disruption of transepithelial chemokine gradients, in MMP2-/- mice affecting only eotaxin (CCL11), but in MMP9-/- and dko mice involving eotaxin, MARC (CCL7), and TARC (CCL17). Thus, by establishing multiple transepithelial chemokine gradients, MMP9 is broadly implicated in the resolution of allergic inflammation, an essential protective mechanism that overlaps with a more limited role played by MMP2.

Variability of inflammatory cell counts on bronchial biopsies of normal subjects

Bronchial biopsies are currently used to study the pathophysiology of airway diseases, and comparisons are often made with biopsies from healthy volunteers. It is therefore important to evaluate the variability in each parameter analyzed in bronchial biopsies of healthy volunteers in order to be able to discriminate significant changes. We analyzed bronchial biopsies of 31 nonsmoking, nonatopic healthy subjects who volunteered as normal controls for studies on pathophysiology of asthma. Mean % epithelial desquamation was 23.7% of observed total epithelial length. No subepithelial fibrosis was observed. Inflammatory cell counts (/mm(2) connective tissue surface) were variable among subjects but not different between small (<or=0.25 mm(2)) and large biopsies. Medians (range) of positive cells were for CD3: 20.5 (0-530.0), CD4: 6.2 (0-124.4), CD8: 1.8 (0-81.5), CD25: 0 (0-62.3), HLA-DR: 80.0 (3.5-524.2), EG1: 5.3 (0-180.6), EG2: 6.4 (0-48.8), AA1: 51.3 (0-286.4), CD45: 39.7 (0-448.5) and CD45ro: 28.6 (0-425.2). Subjects living in an urban area had significantly higher CD8-positive cell counts than those from suburban areas ( p = 0.0001). The presence of an animal at home was associated with lower positive cell counts for CD4 ( p = 0.02), CD45 ( p = 0.02) and HLA-DR ( p = 0.01). In conclusion, the variability in the number and expression of markers of activity of bronchial immune cells in normal subjects likely reflects variable host responses to environmental exposures and must be taken into account when compared to specimens obtained in subjects with airway diseases.

An in vitro airway wall model of remodeling

Recent studies have shown that mechanical forces on airway epithelial cells can induce upregulation of genes involved in airway remodeling in diseases such as asthma. However, the relevance of these responses to airway wall remodeling is still unclear since 1). mechanotransduction is highly dependent on environment (e.g., matrix and other cell types) and 2). inflammatory mediators, which strongly affect remodeling, are also present in asthma. To assess the effects of mechanical forces on the airway wall in a relevant three-dimensional inflammatory context, we have established a tissue culture model of the human airway wall that can be induced to undergo matrix remodeling. Our model contains differentiated human bronchial epithelial cells characterized by tight junctions, cilia formation, and mucus secretion atop a collagen gel embedded with human lung fibroblasts. We found that addition of activated eosinophils and the application of 50% strain to the same system increased the epithelial thickness compared with either condition alone, suggesting that mechanical strain affects airway wall remodeling synergistically with inflammation. This integrated model more closely mimics airway wall remodeling than single-cell, conditioned media, or even two-dimensional coculture systems and is relevant for examining the importance of mechanical strain on airway wall remodeling in an inflammatory environment, which may be crucial for understanding and treating pathologies such as asthma.

The promoter polymorphism in the eosinophil cationic protein gene and its influence on the serum eosinophil cationic protein level

Asthma is characterized by reversible airway obstruction and airway inflammation. Serum levels of eosinophil cationic protein (ECP) might reflect eosinophilic airway inflammation and asthma activity. However, serum ECP levels are not elevated in some patients with asthma, even when they are symptomatic. In this study, we screened for polymorphisms in the ECP gene and analyzed association between these polymorphisms and asthma and serum ECP levels in 137 Japanese families identified through children with asthma. We identified three polymorphisms (-393C/T, -38C/A, and 124Arg/Thr) in human ECP. We did not find associations between these polymorphisms and asthma by the transmission disequilibrium test. However, we found that serum ECP levels in subjects with the -393T allele were significantly lower than those in subjects with the -393C allele. A reporter construct with the -393T allele showed significantly lower promoter activity than one with the -393C allele. Gel shift assay revealed that C/EBP proteins can bind the -393C/T polymorphic site. These data indicate that C/EBP proteins play an important role in the regulation of ECP and that a significant amount of the variance in baseline serum ECP levels may be explained by the -393C/T polymorphism. Although ECP polymorphisms are not likely to be involved in the development of asthma, measurement of ECP levels for the assessment of asthma activity may be improved when done in combination with genotyping of the -393C/T polymorphism.

Improvement in bronchial hyperresponsiveness with inhaled corticosteroids in children with asthma: importance of family history of bronchial hyperresponsiveness

The extent of improvement in bronchial hyperresponsiveness (BHR) with corticosteroids varies considerably among patients with asthma, although predictive factors for improvement are largely unknown. We tested the hypothesis that the improvement may vary according to family history of BHR. Children with atopic asthma (n = 121) received inhaled budesonide (800 micro g per day) regularly for 6 months. Methacholine provocative concentration causing a 20% fall in FEV(1) was measured before treatment and again after 3 and 6 months of treatment. A methacholine challenge test was also performed in each patient's parents, and the results were analyzed with regard to their children's response to corticosteroid therapy. When the children were classified into large (n = 40) and small (n = 40) improvement groups after 6 months of treatment, the prevalence of BHR and the bronchial responsiveness index were higher in parents of the small improvement group (28.8%, 1.145 +/- 0.104) than in parents of the large improvement group (6.3%, 1.095 +/- 0.064; both, p < 0.01). The magnitude of improvement in BHR at 6 months was lower in children with at least one parent with BHR (n = 45; 1.666 +/- 1.244 doubling doses) than in children with non-BHR parents (n = 76; 2.531 +/- 1.726, p < 0.01). Our results suggest that a family history of BHR may be an important factor in the sensitivity of BHR of individuals with asthma to inhaled corticosteroids.

Reduction of eosinophilic inflammation in the airways of patients with asthma using montelukast

OBJECTIVE

Leukotrienes (LTs) are involved in airway eosinophilic inflammation in patients with asthma. We examined the effects of a cysteinyl LT 1-receptor antagonist, montelukast, on sputum eosinophil levels, and the correlation between sputum eosinophils and bronchodilatation in patients with asthma.

DESIGN

Double-blind, randomized, crossover study.

SETTING

University hospital and private hospital.

PATIENTS

Twenty-nine patients with mild-to-moderate asthma.

INTERVENTIONS

Montelukast, 10 mg, and placebo tablet, once daily, each for 4 weeks.

MEASUREMENTS

Sputum eosinophils analyzed using hypertonic saline solution-induced sputum and airway hyperresponsiveness to histamine were evaluated before and after treatment. In addition, morning and evening peak expiratory flow (PEF), asthma symptoms, and peripheral blood eosinophil levels were assessed.

RESULTS

The percentage of eosinophils in sputum decreased from 24.6 +/- 12.3% at baseline to 15.1 +/- 11.8% after montelukast treatment, for a change of - 9.5 +/- 12.7% (n = 20). During placebo administration, the percentage of eosinophils fell from 21.3 +/- 12.1% to 21.0 +/- 11.5%, resulting in a decrease of - 0.3 +/- 10.8% (n = 20). There was a statistically significant difference in the change in sputum eosinophil levels between these two periods (p < 0.005). The number of peripheral blood eosinophils also significantly decreased after montelukast treatment (314.1 +/- 237.6/mL) compared with placebo (413.1 +/- 232.1/mL; p < 0.005, n = 21). Although morning and evening PEF values were significantly improved from baseline after montelukast treatment (p < 0.01, n = 20), asthma symptoms and airway responsiveness to histamine were not significantly altered. Furthermore, there was no significant correlation between the decrease in sputum eosinophils and the increase in PEF.

CONCLUSION

These results suggest that montelukast has anti-inflammatory effects on the airway in patients with asthma, and that its bronchodilatory effect is not solely dependent on a decrease in airway eosinophilia.

Atopic NC/Nga mice as a model for allergic asthma: severe allergic responses by single intranasal challenge with protein antigen

Since certain characters of allergic asthma are common with other allergic disorders like atopic dermatitis, the possible relationship in etiology is expected. Herein, we investigated whether NC/Nga mice, an inherent animal model for human atopic dermatitis, are inclined to allergic asthma. A single intranasal challenge of NC/Nga mice immunized with ovalbumin (OVA) resulted in an increase in plasma levels of OVA-specific IgE, and typical pathological aspects of allergic asthma characterized by infiltration of numerous eosinophils, mucus hyper production of bronchial epithelial cells. Moreover, airway hyperresponsiveness to inhaled acetylcholine and marked enhancement of airway resistance after the challenge were observed as compared to control BALB/c mice. Delayed expression of mRNA of eosinophil active chemokines, interleukin-5, eotaxin, macrophage inflammatory protein-1alpha in concert with eosinophilia was determined in the lung of NC/Nga mice. These results suggest that asthmatic responses developed in NC/Nga mice challenged with OVA are very similar to human allergic asthma, and that NC/Nga mice are a useful model to elucidate various aspects of allergic asthma.

Atopic NC/Nga mice as a model for allergic asthma: cytokine profiles and eosinophil productivity of bone marrow

In previous study, NC/Nga mice with experimentally induced asthma showed severe eosinophilia. To explore the mechanism, profiles of representative cytokines interleukin (IL)-4, IL-5, and interferon (IFN)-gamma were examined in bronchoalveolar lavage fluid. The level of only IFN-gamma was lower in NC/Nga mice than control BALB/c mice. Furthermore, bone marrow cell culture system under the presence of eosinopoietic cytokines, which induce the differentiation of progenitor cells into mature eosinophils, showed that a larger number of eosinophils differentiated from NC/Nga mice derived bone marrow cells than from control BALB/c mice. These results may imply the possibility that severe eosinophilia in the NC/Nga mice are attributable to lower production of IFN-gamma and higher eosinophil productivity of bone marrow cells.

Bronchoalveolar lavage cellular composition in acute asthma and acute bronchiolitis

OBJECTIVE

To compare cellular inflammation in the airways between acute bronchiolitis and asthma.

STUDY DESIGN

Using a bronchoalveolar lavage with flexible bronchoscopy procedure, we investigated the cellular constituents of BAL fluid in children with acute exacerbation of asthma (n = 18) and infants with acute bronchiolitis caused by respiratory syncytial virus (n = 20). These results were compared with those of healthy control subjects (n = 14).

RESULTS

Total lavage fluid recovered was similar in all groups. The total cell numbers were highest in the bronchiolitis group. The BAL cellular profile in the asthma group was characterized by a higher median (interquartile range) ratio of eosinophils (2.4% [1.6%-9.5%]; P <.01) than in the bronchiolitis group (0% [0%-0%]) or the control group (0% [0%-0%]). Neutrophil ratio was higher in the bronchiolitis group (40.0% [26.5%-50.0%]; P <.01), with no difference found between the asthma group (3.3% [2.0%-7.9%]) and the control group (2.0% [0.8%-5.5%]).

CONCLUSIONS

Asthma and acute bronchiolitis are characterized by an elevated cellular percentage of eosinophils and neutrophils, respectively, in bronchoalveolar lavage fluid.

Bradykinin stimulates eotaxin production by a human lung fibroblast cell line

BACKGROUND

Bradykinin, a potent inflammatory peptide, is increased in the airways of allergic patients. Accompanying the elevated bradykinin levels are increases in both eosinophils and fibroblasts. Eotaxin, a potent eosinophil-specific chemotactic factor, is released by fibroblasts and increased in the lower respiratory tract of allergic patients.

OBJECTIVE

We sought to test the hypothesis that lung fibro-blasts release eotaxin in response to bradykinin.

METHODS

The potential of bradykinin to induce the release of eotaxin from the human lung fibroblast cell line HFL-1 was tested by cell culture and evaluation of the culture supernatant fluids and RNA for immunoreactive eotaxin and eotaxin messenger RNA.

RESULTS

HFL-1 cells released eotaxin constitutively without stimulation, but bradykinin stimulated eotaxin release in a dose- and time-dependent manner and resulted in augmented expression of eotaxin messenger RNA. The release of eotaxin was sensitive to the action of glucocorticoids. Eosinophil chemotactic activity by HFL-1 supernatant fluids was inhibited by anti-human eotaxin-neutralizing antibody. Consistent with these results, inhibitors of bradykinin B2 receptors, but not bradykinin B1 receptors, inhibited bradykinin-induced eotaxin release.

CONCLUSION

These data demonstrate that bradykinin may stimulate lung fibroblasts to release eotaxin and suggest the potential for this mechanism to be important in modulation of lung inflammation.

Genetic variability in pulmonary physiological, cellular, and antibody responses to antigen in mice

Wide differences among inbred mouse strains in susceptibility to develop components of asthmalike pulmonary changes would provide insights into the nature of the relationships among those components and set the stage for genetic approaches to their etiology. We therefore examined pulmonary pathophysiological and serum immunoglobulin (Ig)E responses in mice of 12 inbred strains sensitized intraperitoneally with ovalbumin (OVA) and repeatedly exposed to aerosolized OVA. One day after the last OVA exposure the intravenous methacholine (MCh) dose required to reduce lung conductance by 50% (ED(50)GL) in OVA-sensitized and exposed mice was reduced by 0 to 2.7-fold, compared with sham-sensitized mice, depending on the strain. In OVA-sensitized mice, bronchoalveolar lavage (BAL) eosinophils comprised from 3.3 +/- 3.1 (SD) to 91.2 +/- 5.0% of BAL cells and eosinophilic pulmonary inflammation varied from being nondetectable to widespread and severe. OVA-specific IgE concentrations ranged from less than 3 ng/ml to 455 ng/ml in different strains. Shifts in responsiveness correlated significantly with pulmonary eosinophilia among strains (r > 0.70, p < 0.001) but not with antigen-specific IgE levels (r = 0.55, p = 0.056). These results demonstrate that allergen- induced enhancement of cholinergic responsiveness, pulmonary eosinophil influx, and elevations of serum antigen-specific IgE levels are each genetically determined and are not always associated.

Long-term topical exposure to toluene diisocyanate in mice leads to antibody production and in vivo airway hyperresponsiveness three hours after intranasal challenge

Toluene diisocyanate (TDI) is a low-molecular-weight compound which is known to cause occupational asthma in 5 to 10% of exposed workers. Previously, we developed a murine model to investigate TDI-induced occupational asthma. Short-term exposure to TDI (skin sensitization twice daily on Day 0 and Day 1 and intranasal challenge on Day 8) led to a nonspecific tracheal hyperractivity 24 h after the challenge in TDI-sensitized mice when compared with nonsensitized mice whereas no TDI-specific IgE antibodies were found in the serum. Because 20% of subjects with TDI-induced occupational asthma exhibit an increase in serum IgE antibodies, we exposed mice for a longer period of time to investigate whether this procedure could induce TDI-specific antibody production in exposed mice. Long-term exposure (skin sensitization on 6 consecutive weeks followed by intranasal challenge on Week 7) resulted in the production of total IgE and IgG and TDI-specific IgE and IgG antibodies. Airway reactivity to various agonists was also measured in vitro and in vivo in long-term exposed mice. TDI-sensitized mice exhibited in vitro tracheal hyperreactivity to carbachol 3 h after the challenge when compared with the nonsensitized mice. Moreover, in vivo airway hyperresponsiveness to serotonin (5-hydroxytryptamine [5HT]) was found 3 h after the challenge in TDI-sensitized mice. Interestingly, in vivo airway hyperresponsiveness was not observed at any time point in the mice exposed to TDI according to the short-term protocol. In conclusion, by altering the exposure time and/or cumulative dosage of TDI different biological reactions can be elicited in exposed mice. This important finding might be a reflection of the diversity of symptoms found in patients suffering from TDI-induced asthma. Both the short-exposure and the long-exposure model will be useful to further investigate the mechanisms of action of TDI.

Allergen-specific immunotherapy for allergic rhinitis: a new insight into its clinical efficacy and mechanism

Immunotherapy has been used widely for allergic diseases for more than 90 years but, in the opinion of many physicians, it is still a controversial form of treatment. The exact mechanism of action of immunotherapy remains to be determined. In the present study, we review the clinical efficacy and mechanism of action of immunotherapy for allergic rhinitis. Recent double-blind placebo-controlled studies have demonstrated the clinical efficacy of immunotherapy for allergic rhinitis. This therapeutic method has several advantages over conventional pharmacological treatment. Immunotherapy is inferior to pharmacological treatment in the short term, but in the long term it is substantially superior with respect to clinical efficacy. Immunotherapy has the potential permanently to alleviate the abnormal immunological responses of allergic rhinitis and to cure the nasal symptoms in the long term, even after discontinuation of injections. In addition, immunotherapy can prevent the onset of new sensitizations in allergic patients and may prevent the progression of rhinitis to asthma. It may therefore be possible for immunotherapy to alter the natural history of allergic sensitization and its clinical manifestation. These lines of clinical evidence could affect strategies of long-term therapy for allergic rhinitis. Modern molecular biological techniques have suggested that immunotherapy may affect allergen-induced TH responses or cytokine profiles, but there is no general agreement among investigators. However, IL-5 is likely to be the most important cytokine involved in the clinical efficacy of immunotherapy, and the suppression of allergen-induced IL-5 synthesis is most likely to be involved in the mechanism of immunotherapy. Our recent investigations, focusing on specific IgE and IgG4 responses, suggest that immunotherapy-induced changes in these specific antibodies play a clinical role and are involved in the mechanism of action of immunotherapy. It is probable that immunotherapy modulates and affects many different immunological and non-immunological phenomena to produce clinical efficacy and that clinical improvement is a consequence of different mechanisms over time.

Granulocyte macrophage colony-stimulating factor augments ICAM-1 and VCAM-1 activation of eosinophil function

Intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) are members of the immunoglobulin superfamily adhesion molecules on vascular endothelium and important in the development of eosinophil (EOS) accumulation in allergic inflammation. To define the role of these adhesion proteins in EOS inflammation, peripheral blood EOS from allergic donors were incubated in either buffer (control)-, recombinant human (rh)-VCAM-1-, or rh-ICAM-1-coated plates, and the effects of these adhesion proteins on EOS effector functions were determined. VCAM-1 induced spontaneous EOS adhesion whereas EOS adhesion to ICAM-1 required a second signal, such as granulocyte macrophage colony-stimulating factor (GM-CSF). Although only VCAM-1 stimulated EOS superoxide anion (O2-) generation, the addition of GM-CSF (100 pM) to the reactions resulted in a greater and equivalent production of O2- with VCAM-1 and ICAM-1. In the presence of GM-CSF, ICAM-1 and VCAM-1 caused significant release of EOS-derived neurotoxin (EDN). Moreover, only ICAM-1 (no GM-CSF) promoted calcium ionophore A23187 (0.2 microM)-induced EOS leukotriene C4 (LTC4). Enhanced O2- generation, EDN release, and LTC4 generation observed with ICAM-1 and VCAM-1 were significantly inhibited by anti-beta2-integrin antibody. These results suggest that ICAM-1 and VCAM-1 are important in determining the eventual function of airway EOS.

Eosinophils and pulmonary function: an epidemiologic study of adolescents and young adults

BACKGROUND AND OBJECTIVE

In order to identify potential risk factors, other than cigarette smoking, for lung function impairment, the relationships of peripheral eosinophil count, bronchial responsiveness to inhaled histamine, skin test reactivity and respiratory symptoms to pulmonary function results in a population sample of 665 adolescents and young adults, aged 13 to 23 years.

METHODS

Case history, especially concerning smoking habits and respiratory symptoms, was obtained by interview and a self administered questionnaire. Pulmonary function, peripheral blood eosinophil counts, bronchial responsiveness to inhaled histamine and skin test reactivity to common allergens were measured using standard techniques. The relationships of peripheral blood eosinophil counts, symptoms of asthma, cigarette smoking, bronchial responsiveness and skin test reactivity were compared with FEV1, adjusted for age, sex, and height.

RESULTS

The peripheral eosinophil count was inversely correlated to FEV1 %predicted (P = .001); and subjects with eosinophilia (defined as > .25 x 10(9) l(-1)) had significantly reduced FEV1 %predicted compared with those without eosinophilia (95 +/- 13 %pred and 102 +/- 16 %predicted, respectively, P = .001). A close direct correlation was observed between blood eosinophils and histamine responsiveness (r = .60; P < .001). In nonatopic subjects (n = 382), the FEV1 %predicted was significantly lower in those with eosinophilia compared with those without. Subjects, who had never smoked, who were nonatopic and nonasthmatic, and who had no evidence of bronchial hyperresponsiveness, were found to have a weak but statistically significant inverse relation between eosinophil count and FEV1 %predicted (r = -.14, P = .04). In the same subgroup, subjects with eosinophilia (n = 27) had reduced FEV1 %predicted compared with those without (n = 177) (96 and 102, respectively, P < .05).

CONCLUSIONS

The findings of this study support the theory that the role of the eosinophil leukocyte in obstructive pulmonary diseases extends beyond its role in allergic reactions, suggesting that an increased number of blood eosinophils reflects an inflammatory reaction in the airways, which might lead to development of obstructive airflow limitation.

Serum eosinophil cationic protein (ECP) and eosinophil protein X (EPX) in childhood asthma: the influence of atopy

The purpose of this study was to determine the value of serum measurements of eosinophil cationic protein (ECP) and eosinophil protein X (EPX) in diagnosing asthma in children, and to investigate the influence of concomitant allergic diseases and atopic sensitization, assessed by skin prick tests (SPT), on these markers. ECP and EPX were determined in 36 children with asthma, in 33 children with other symptoms from lower airways disease (OSLA), and in 166 control children. Sixteen children with asthma but no anti-inflammatory therapy had significantly higher concentrations of ECP and EPX (ECP: 27.5 microg/L, P < 0.001; EPX: 59.9 microg/L, P < 0.001) than the control children (ECP: 11.2 microg/L; EPX: 26.2 microg/L). In the 20 children on anti-inflammatory therapy, ECP values were similar to those of controls. The children with OSLA (ECP: 13.6 microg/L, P < 0.01; EPX: 47.2 microg/L, P < 0.001) differed significantly from controls. When using the value of 24.7 microg/L (97.5 percentile in the 68 non-atopic controls) as a pathologic upper limit for ECP, 10 (63%) of the 16 asthmatic children on no maintenance medication, two (10%) of the 20 asthmatics on maintenance therapy, and 11 (33%) of the 33 children with OSLA had high ECP; the same figure was only 18 (11%) in the 166 control children. Both ECP and EPX had a significant association with allergic disorders and with SPT reactivity. In multivariate logistic regression analysis, an elevated ECP was significantly associated with asthma (OR 2.3, 95%CI 1.1-4.9) and atopic dermatitis (2.9, 1.2-6.9), and an elevated EPX was significantly associated with asthma (2.61, 1.19-5.74) and allergic rhinoconjunctivitis (5.23, 1.46-18.73). We conclude that serum concentrations of both ECP and EPX are higher in asthmatic than in healthy children. However, other allergic diseases, such as allergic rhinoconjunctivitis, atopic dermatitis, and allergic skin sensitization also raise the concentrations of these markers. This limits their usefulness in the diagnosis of childhood asthma.

Effect of immunotherapy on serum levels of eosinophil cationic protein in perennial allergic rhinitis

Eosinophil cationic protein (ECP) levels in the serum of clotted blood could reflect the rate of activation of circulating eosinophils. We investigated the serum ECP levels in patients with perennial allergic rhinitis, with special reference to the effect of immunotherapy on the serum ECP levels. Serum ECP levels in untreated patients with perennial allergic rhinitis are significantly higher than those of nonatopic volunteers. Therefore, this elevation in the untreated patients represents an ongoing inflammation occurring in allergic rhinitis. The mean serum ECP level of a 1-year immunotherapy group was significantly higher than that of the nonatopic group, and was not different from that of the untreated group. In contrast, the mean serum ECP level in patients who had more than 2 years of immunotherapy was significantly lower than that of the untreated group, and was not different from that of the nonatopic group. Additionally, serum ECP levels were significantly correlated with the duration of immunotherapy. These findings suggest that activation of circulating eosinophils decreases gradually during immunotherapy, but this inhibition becomes apparent only after 2 years of immunotherapy. The control of circulating eosinophil activation might be one of the important working mechanisms behind the clinical effect of immunotherapy.

Bronchoalveolar lavage findings suggest two different forms of childhood asthma

BACKGROUND

It seems plausible that children with atopy and persistent asthma symptoms will, like their adult counterparts, have chronic airways inflammation. However, many young children with no other atopic features have episodic wheezing that is triggered solely by viral respiratory infections. Little is known as to whether airways inflammation occurs in these two asthma patterns during relatively asymptomatic periods.

METHODS

Using a non-bronchoscopic bronchoalveolar lavage (BAL) procedure on children presenting for an elective surgical procedure, this study has investigated the cellular constituents of BAL fluid in children with a history of atopic asthma (AA) non-asthmatic atopic children (NAA) or viral associated wheeze (VAW).

RESULTS

A total of 95 children was studied: 52 with atopic asthma (8.0 years, range 1.1-15.3, 36 male), 23 with non-asthmatic atopy (median age 8.3 years, range 1.7-13.6, 11 male) and 20 with VAW (3.1 years, range 1.0-8.2, 13 male). No complications were observed during the lavage procedure and no adverse events were noted post-operatively. Total lavage fluid recovered was similar in all groups and the total cell numbers were higher in the VAW group. Eosinophil (P < or = 0.005) and mast cell (P < or = 0.05) numbers were significantly elevated in the group with atopic asthma.

CONCLUSIONS

During relatively asymptomatic periods there is on-going airways inflammation, as demonstrated by eosinophil and mast cell recruitment, in children with asthma and atopy but not in children with viral associated wheeze or atopy alone. This strongly suggests that there are different underlying pathophysiological mechanisms in these two groups of children who wheeze.

Bronchial subepithelial fibrosis correlates with airway responsiveness to methacholine

OBJECTIVES

To evaluate the relationships between airway subepithelial collagen deposition and epithelial desquamation with airflow obstruction and hyperresponsiveness in different types of asthma and other respiratory conditions such as chronic cough and allergic rhinitis.

DESIGN AND PARTICIPANTS

We compared the histopathologic features observed on bronchial biopsy specimens obtained from 80 subjects: 38 with different types of asthma, 19 with chronic cough, 13 with allergic rhinitis, and 10 normal control subjects. Each subject had a questionnaire on respiratory symptoms and medication needs, measurements of expiratory flows and methacholine responsiveness, allergy skin prick tests, and a bronchoscopy with bronchial biopsies. None of the subjects studied used bronchial anti-inflammatory agents.

RESULTS

Different degrees of bronchial subepithelial fibrosis were present in asthmatic subjects, the most intense being observed in occupational asthma; a subepithelial deposition of collagen was also found in subjects with allergic rhinitis, although it was less intense than in asthma and irregularly distributed under the basement membrane. On global analysis, we found a significant correlation between individual provocative concentration of methacholine inducing a 20% fall in FEV1 (PC20) and subepithelial fibrosis intensity (rs=-0.70, p<0.001). The degree of epithelial desquamation was correlated with that of subepithelial fibrosis (rs=0.36, p=0.02) in subjects with normal airway responsiveness, but it was not correlated with the PC20 (rs=0.10, p>0.05). Neither the degree of subepithelial fibrosis nor epithelial desquamation was correlated with the FEV1.

CONCLUSION

These results suggest that structural airway changes such as subepithelial collagen deposition may be significant determinants or markers of a process that results in airway hyperresponsiveness.

Expression of vascular endothelial growth factor by human eosinophils: upregulation by granulocyte macrophage colony-stimulating factor and interleukin-5

Vascular endothelial growth factor (VEGF) is a pleiotropic polypeptide that mediates endothelial-cell-specific responses such as induction of proliferation and vascular leakage. We examined the expression of VEGF messenger RNA (mRNA) and protein by human eosinophils in response to granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-5 (IL-5). Immunoreactive VEGF protein was detected in freshly isolated eosinophils by immunocytochemistry. Eosinophils spontaneously released VEGF protein in culture medium, and this release was upregulated by GM-CSF or IL-5. Freshly isolated eosinophils constitutively expressed VEGF mRNA. Although incubation of eosinophils in culture medium reduced steady-state VEGF mRNA levels, eosinophil VEGF mRNA levels were enhanced by GM-CSF and IL-5, and this enhancement was blocked by the transcription inhibitor actinomycin D. Analysis of alternatively spliced mRNA species revealed that eosinophils contained transcripts mainly encoding for the 121- and 165-amino-acid forms of VEGF. VEGF mRNA expression and VEGF release in cytokine-stimulated eosinophils were significantly reduced by treatment with a glucocorticosteroid, a protein-tyrosine kinase inhibitor, or a protein kinase C inhibitor. Cytokine-activated eosinophils may be an important source of a vascular permeability factor, namely VEGF, thus contributing to tissue edema formation at sites of allergic inflammation.

Blood sample processing effect on eosinophil cationic protein concentration

BACKGROUND

Asthma is considered to be an inflammatory disease. The most important cell involved in the inflammation is the eosinophil. These cells and their mediators, such as eosinophil cationic protein (ECP), are potential markers of the inflammation's severity. Eosinophil cationic protein may be used for monitoring antiasthma treatment. It is well known that sample processing conditions can affect the ECP blood levels.

OBJECTIVE

The aim of this work is to study the effect of temperature, time, and anticoagulants on ECP levels.

METHODS

We studied five asthmatic patients and five healthy controls. We obtained three different blood samples from each subject, one with heparin, one with EDTA, and one without anticoagulant. To evaluate the effect of temperature, serum samples were clotted for an hour, one at 0 degree C, one at room temperature, and the other at 37 degrees C. Plasma (heparin and EDTA) samples were treated as follows: one was immediately centrifuged, and two were stored for an hour, one at 0 degree C, and the other at room temperature. Eosinophil cationic protein levels were measured by fluoroimmunoassay (CAP-System ECP FEIA Pharmacia).

RESULTS

A higher temperature during blood clotting resulted in a higher ECP concentration. There were no differences between ECP determination in serum samples and plasma samples with heparin, under the same conditions of time and temperature; so clotting may not be necessary for ECP release in vitro. Eosinophil cationic protein was not released in plasma samples with EDTA, neither at 0 degree C nor room temperature.

CONCLUSIONS

More studies must be done to clarify the mechanism of the ECP release in vitro.

Eosinophil peroxidase stimulates the release of granulocyte-macrophage colony-stimulating factor from bronchial epithelial cells

BACKGROUND

Asthma is characterized by an accumulation of activated eosinophils in the airway. Eosinophil viability-enhancing activity is present in the sputum of patients with asthma, largely because of granulocyte-macrophage colony-stimulating factor (GM-CSF). Bronchial epithelial cells have been shown to release cytokines including GM-CSF when stimulated with IL-1 beta or tumor necrosis factor-alpha.

OBJECTIVE

The study was designed to determine whether eosinophil peroxidase (EPO) stimulates the release of GM-CSF from bronchial epithelial cells.

METHODS

Epithelial cells (BEAS-2B) were cultured in serum free HD-F12 medium in a 24-well tissue culture plate until they became confluent. The cells were then exposed to EPO (5.9 x 10(-8) to 5.9 x 10(-7) mol/L) for 15 minutes, washed twice, and cultured in 1 ml of HD-F12. The supernatants were harvested at 3, 6, or 24 hours, and GM-CSF concentration was measured by ELISA. BEAS-2B cells were also treated with a system comprising EPO (1.9 x 10(-9) to 5.9 x 10(-8) mol/L) + 10(-5) mol/L H2O2 + 10(-4) mol/L Br for 24 hours.

RESULTS

The GM-CSF concentration in the supernatant pretreated with EPO increased in a time- and concentration-dependent manner compared with control. The release of GM-CSF was not inhibited by catalase but was inhibited by cyclohexamide and by mixing of EPO with heparin, suggesting that the action is due to the cationic property of EPO. When EPO was combined with H2O2 and Br, 5.9 x 10(-9) mol/L EPO + 10(-5) mol/L H2O2 released two times more GM-CSF into the supernatants compared with control.

CONCLUSION

These results suggest that EPO stimulates epithelial cells to release GM-CSF and forms a self-stimulatory cycle.

Anti-inflammatory effects of theophylline, cromolyn and salbutamol in a murine model of pleurisy

1. The aim of this study was to examine the effect of theophylline, cromolyn and salbutamol, three well-known anti-asthmatic drugs, on the early (4 h) and late (48 h) phases of cell migration and fluid leakage induced by carrageenin in the pleural cavity of mice. 2. In the first set of experiments, animals were pretreated (30 min) with different doses of theophylline (0.5-50 mg kg-1, i.p.), cromolyn (0.02-0.2 mg per pleural cavity) or salbutamol (0.05-50 mg kg-1, i.p.); the total and differential cell content, and also the exudate were analysed 4 h after carrageenin (1%) administration. Afterwards, in order to evaluate the time course effects of these drugs on both phases of the inflammatory reaction, one dose employed in the above protocol was chosen, to pretreat (0.5-24 h) different groups of animals. The studied parameters were evaluated 4 and 48 h after pleurisy induction. 3. Acute administration of theophylline (1-50 mg kg-1, i.p.) cromolyn (0.02-0.2 mg per pleural cavity) and salbutamol (0.5-50 mg kg-1, i.p.), 30 min prior to carrageenin, caused significant inhibition of total cell and fluid leakage in the pleural cavity at 4 h (P < 0.01). All drugs exerted a long-lasting inhibitory effect on both exudation and cell migration (P < 0.01) when administered 0.5-8 h before pleurisy induction. However, the temporal profile of the inhibitory effect induced by these drugs on the first phase of the inflammatory reaction was clearly different. Thus, the inhibitory effect induced by theophylline and cromolyn on exudation was significantly longer (up to 24 h) in comparison to their effects on cell migration (only up to 8 h). In contrast, although salbutamol when administered 30 min before pleurisy induction abolished fluid leakage (P < 0.01), this effect was not sustained in the groups pretreated for 4-8 h. In these latter groups, a significant but much smaller reduction of exudation was observed (P < 0.01), whereas the magnitude of cell migration inhibition did not vary. 4. The second phase (48 h) of the inflammatory reaction induced by carrageenin (1%) was significantly inhibited by cromolyn (0.02 mg per pleural cavity) when this drug was administered 0.5-24 h before pleurisy induction (P < 0.01). Similar results were observed when theophylline (50 mg kg-1, i.p.) was administered 0.5-4 h before the injection of the phlogistic agent (P < 0.01). Treatment of the animals with salbutamol (5 mg kg-1, i.p.), 0.5-24 h before pleurisy induction, did not inhibit either cell migration or fluid leakage. In this condition, a significant increase of these parameters was observed in the group pretreated with salbutamol 8-24 h before pleurisy induction (P < 0.01). 5. These results indicate that theophylline and cromolyn were able to inhibit the early (4 h) and late (48 h) phases of the inflammatory reaction induced by carrageenin in a murine model of pleurisy. Salbutamol was effective only against the early phase. The inhibitory effects of theophylline, cromolyn and salbutamol on the early phase of this inflammatory reaction were long-lasting, although a distinct profile of inhibition was observed among them. These findings confirm and extend previous results described in other models of asthma and support both clinical and experimental evidence suggesting that these anti-asthmatic agents exhibit marked anti-inflammatory properties.

Potassium channel activation: a potential therapeutic approach?

The physiological role of K+ channel opening by endogenous substances (e.g., neurotransmitters and hormones) is a recognised inhibitory mechanism. Thus, the identification of novel synthetic molecules that 'directly' open K+ channels has led to a new direction in the pharmacology of ion channels. The existence of many different subtypes of K+ channels has been an impetus in the search for new molecules demonstrating channel and, thus, tissue selectivity. This review focuses on the different classes of openers of K+ channels, the intracellular mechanisms involved in the execution of their effects, and potential therapeutic targets.

Inhibition of some aspects of acute inflammation of guinea-pig lung by intraperitoneal dexamethasone and mifepristone: demonstration of agonist activity of mifepristone in the guinea-pig

We have determined the inhibitory activity of dexamethasone as an inhibitor of histamine-induced plasma protein extravasation (PPE) in guinea-pig lung and skin, and of lipopolysaccharide (LPS)-induced neutrophilia and platelet activating factor (PAF)-induced eosinophilia in guinea-pig lungs. Dexamethasone inhibited PAF-induced eosinophilia in guinea-pig lung (ED50 1.4 mg/kg i.p.). Higher doses of dexamethasone were required to inhibit LPS-induced neutrophilia (ED50 10.8 mg/kg i.p.). However, at doses up to 150 mg/kg i.p. dexamethasone did not inhibit histamine-induced plasma protein extravasation (PPE) in guinea-pig lung, but did inhibit PPE in guinea-pig skin. These preparations have previously been shown to be equally sensitive to inhibition by the beta 2-adrenoceptor agonist salmeterol. Dexamethasone inhibited PAF-induced eosinophilia (5 mg/kg) or LPS-induced neutrophilia (50 mg/kg) when given 3 h or 1 h prior to challenge. Inhibitory activity was lost when dexamethasone was administered 23 h prior to LPS or 1 h after PAF. The glucocorticoid antagonist mifepristone (1-100 mg/kg i.p.) caused dose-related inhibition of PAF-induced eosinophilia but not of LPS-induced neutrophilia. The highest dose of mifepristone used (100 mg/kg) did not reverse the inhibitory actions of dexamethasone (50 mg/kg) on LPS-induced neutrophilia. We suggest that the different inhibitory activity of dexamethasone in the preparations studied indicates differences in the sensitivity of the target cells involved to inhibition by dexamethasone. We also suggest that inhibition of PAF-induced eosinophilia by mifepristone reflects the partial agonist activity of this agent, demonstrated by others in different experimental systems.

Crescentic glomerulonephritis and eosinophilic interstitial infiltrates in a patient with hypereosinophilic syndrome

Crescentic glomerulonephritis with immune complex deposition and acute eosinophilic interstitial nephritis developed in a patient with the hypereosinophilic syndrome. Acute renal failure ensued but was rapidly reversed by high-dose oral prednisone. Confounding factors and unusual findings are described with a review of recent literature. This mode of presentation has not previously been reported.

Inhibitory effect of CP-96,345, a non-peptide neurokinin-1-receptor antagonist, on neurogenic responses of guinea-pig isolated airway smooth muscle

The actions of CP-96,345, a non-peptide neurokinin-1 receptor antagonist, on the responses evoked by electrical-field stimulation or by acetylcholine and substance P in guinea-pig tracheal and bronchial muscle strips were examined. Electrical-field stimulation evoked a biphasic response, consisting of a cholinergically-mediated fast contraction followed by non-adrenergically-mediated relaxation in tracheal muscle and by a non-cholinergically-mediated slow contraction in bronchial muscle. CP-96,345 (1-10 microM) caused a concentration-dependent and non-selective inhibition in the amplitude of these neurogenic responses, where non-cholinergic contractions were more profoundly inhibited. Submaximal contractions of tracheal and bronchial muscles evoked by exogenous substance P (0.1-3 microM) were partly inhibited by CP-96,345 (1-10 microM), but acetylcholine-induced contractions were hardly inhibited. The results indicate that in guinea-pig isolated airway smooth muscle CP-96,345 can non-selectively inhibit neurogenic responses probably via neurokinin-1 receptor-dependent and independent mechanisms.

Effects of dexamethasone in a model of lung hyperresponsiveness in the rat

In rats, Sephadex treatment on days 0, 2 and either 4 or 5 resulted in a blood and lung eosinophilia, an increase in lung cell fragility, an increase in the functional activity of peritoneal eosinophils in vitro and a sustained increased responsiveness of lung parenchymal strips to KCl, 5-hydroxytryptamine (5-HT) and carbachol that was not associated with oedema or gross fibrosis. The corticosteroid dexamethasone, when given before each injection of Sephadex, reduced all these effects of Sephadex. When given 30 min after the last injection of Sephadex, dexamethasone had no effect on the number of blood and lung eosinophils but it did reduce the functional activity of peritoneal eosinophils, the increased lung cell fragility and the hyperresponsiveness to 5-HT. Repeated administration of dexamethasone to rats with an established hyperresponsiveness that was no longer associated with cellular inflammation had minimal effects on this hyperresponsiveness.