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P Bradding

Publications and source records attributed to P Bradding.

At least 37 records · Page 2Linked to original sources
PubMed2000

Localization of interleukin (IL) -4 but not IL-5 to human mast cell secretory granules by immunoelectron microscopy.

BACKGROUND: Human mast cells synthesize and secrete many cytokines of relevance to the pathogenesis of allergic diseases such as asthma and rhinitis. In particular, interleukin (IL) -4 and IL-5 are likely to play key roles in the development of the inflammatory response that characterizes these diseases. Immunohistochemical studies on human nasal and bronchial mucosal biopsies suggest that IL-4 and IL-5 may be stored preformed in mast cells. OBJECTIVE: To identify whether IL-4 and IL-5 are stored within mast cell secretory granules. METHODS: We used immunogold electron microscopic analysis on bronchial mucosa and lung parenchyma from resected lung specimens, and a nasal mucosal biopsy from a patient with active allergic rhinitis. Samples were fixed in 4% paraformaldehyde plus 0.5% glutaraldehyde and processed into Lowicryl K4M resin by the 'Progressive Lowering of Temperature' technique. Ultrathin sections were stained immunohistochemically by an indirect immunogold method. RESULTS: Immunoreactivity for IL-4, but not IL-5, was localized to the granules of mast cells in all tissue samples. IL-5 was localized to the matrix of eosinophil granules in these samples, but neither cytokine was detected in T cells. IL-4 immunoreactivity increased in the granules of mast cells 24 h after immunoglobulin (Ig) E-dependent activation (mean 17.5 +/- 1.4 gold particles per granule) compared with nonactivated mast cells (mean 6.8 +/- 0.8 gold particles per granule, P < 0.001), suggesting replenishment of stores by newly generated protein. Immunoreactive IL-5 remained undetectable in mast cells 24 h after activation, a time point at which they are known to secrete large quantities of this cytokine. CONCLUSION: Human mast cells store IL-4 within the matrix of their granules. Very few, if any, lung or nasal mast cells store IL-5. A store of preformed IL-4 within mast cell granules is likely to have an important influence during the initiation and maintenance of the allergic immunological response.

Cytoplasmic Granules↗
PubMed2000

TB guidelines.

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Antitubercular Agents↗
PubMed2000

Induced sputum inflammatory mediator concentrations in eosinophilic bronchitis and asthma.

Eosinophilic bronchitis is a common cause of chronic cough, which like asthma is characterized by sputum eosinophilia, but in contrast to asthma there is no variable airflow obstruction or airway hyperresponsiveness. Our hypothesis was that the differences in airway pathophysiology maybe due to less active airway inflammation in eosinophilic bronchitis, with reduced release of important effector mediators. We measured the concentration of various proinflammatory mediators in induced sputum cell-free supernatant in eight patients with eosinophilic bronchitis, 17 patients with asthma matched for sputum eosinophil count, and 10 normal subjects. Cysteinyl-leukotrienes (cys-LT) were measured by enzyme immunoassay, eosinophilic cationic protein (ECP) by fluoroimmunoassay, prostanoids (PGE(2), PGD(2), TXB(2), and PGF(2alpha)) by gas chromatography-negative ion chemical ionization-mass spectroscopy, and histamine by radioenzymic assay. The geometric mean sputum eosinophil count was similar in asthma (13.4%) and eosinophilic bronchitis (12.5%). Sputum cys-LT and ECP were a mean (95% CI) 1.6-fold (1.1, 2.5) and 6.4-fold (1.4, 28) higher in eosinophilic bronchitis and 1.9-fold (1.3, 2.9) and 7.7-fold (1.2, 46) higher in asthma compared with that in control subjects (geometric mean, 5.9 and 95 ng/ml, respectively). In eosinophilic bronchitis the mean concentration of sputum PGD(2) (0.79 ng/ml) and histamine (168 ng/ml) were significantly higher than in asthma (mean absolute difference in PGD(2) concentration, 0.47 ng/ml [95% CI, 0.19 to 0. 74] and mean-fold difference in histamine concentration, 6.7 [95% CI 1.7 to 26]) and normal subjects (0.64 ng/ml [0.36 to 0.90] and 11-fold [3.3 to 36]), respectively. In conclusion, eosinophilic bronchitis is associated with active airway inflammation with increased release of vasoactive and bronchoconstrictor mediators.

Adult↗
PubMed2000

Adhesion of human lung mast cells to bronchial epithelium: evidence for a novel carbohydrate-mediated mechanism.

Mast cells contribute to the pathophysiology of asthma through their immunomediator-secretory activity in response to both immunological and nonimmunological stimuli, and infiltrate the bronchial epithelium in this disease. We hypothesized that human lung mast cells (HLMC) localize to the bronchial epithelium via a specific cell-cell adhesion mechanism. We investigated the adhesion of HLMC to primary bronchial epithelial cells and the bronchial epithelial cell line BEAS-2B. HLMC adhered avidly to both primary cultures of bronchial epithelial cells and BEAS-2B cells (mean adhesion 68.4 and 60.1%, respectively) compared with eosinophil adhesion to BEAS-2B (mean adhesion 10.3%). HLMC adhesion did not alter after epithelial activation with cytokines, did not require Ca2+, and was not integrin-mediated. IgE-dependent activation of HLMC produced an approximately 40% inhibition of adhesion. There was significant attenuation of adhesion after incubation of HLMC with pronase, beta-galactosidase, and endo-alpha-N-acetylgalactosaminidase, indicating that HLMC adhere to bronchial epithelial cells via galactose-bearing carbohydrates expressed on a cell-surface peptide(s).

Antibodies, Monoclonal↗
PubMed1999

Immunopathology and human mast cell cytokines.

The mast cell is a virtual pharmacopoeia of biological substances. It used to be believed that mast cell activation was all-or-nothing, with IgE cross-linking inducing symptoms of allergy and anaphylaxis. However, the activity of mast cells in health and disease is clearly much more complicated than this. The discovery that human mast cells secrete many pleiotropic cytokines suggested there may be many novel mast cell functions, and many of these are now being realised. The ubiquitous distribution of mast cells throughout connective tissues, along epithelial surfaces, and in close proximity to blood vessels, makes their products available to a large variety of cell types including fibroblasts, glandular epithelial cells, nerves, vascular endothelial cells, smooth muscle cells, and other cells of the immune system. This tissue distribution, and the vast array of lipid mediators, proteases, proteoglycans and cytokines identified as potential products of human mast cells, explains how this interesting cell has the potential to contribute to so many diverse biological events.

Animals↗
PubMed1999

As-required versus regular nebulized salbutamol for the treatment of acute severe asthma.

Current British guidelines for the administration of beta2-agonists in acute severe asthma recommend regular nebulized therapy in hospitalized patients, followed by as-required (p.r.n.) use via hand-held devices after discharge. Since beta2-agonists do not possess anti-inflammatory activity in vivo, and are thus unlikely to influence the rate of recovery from an asthma exacerbation, it was hypothesized that patients given the short-acting beta2-agonist salbutamol on an as-required basis after admission to hospital would recover as quickly as those on regular treatment, but with potential reductions in the total dose delivered. Forty-six patients with acute severe asthma were randomly assigned to either regular prescriptions of nebulized salbutamol or to usage on a p.r.n. basis, from 24 h after hospital admission. The primary outcome measures were length of hospital stay, time to recovery, and frequency of salbutamol nebulization from 24 h after admission to discharge. Secondary outcome measures were treatment side-effects (tremor, palpitations), and patient satisfaction. Length of hospital stay was reduced in those patients allocated to p.r.n. salbutamol (geometric mean (GM) 3.7 days) versus regular salbutamol (GM 4.7 days). Time taken for peak expiratory flow to reach 75% of recent best was the same in both groups. There was a highly significant reduction in the number of times nebulized therapy was delivered to the p.r.n. group (GM 7.0, range 1-30) compared with the regular treatment group (GM 14.0, range 4-57; p=0.003; 95% confidence interval for ratio of GMs 1.29-3.09). In addition, patients reported less tremor (p=0.062) and fewer palpitations (p=0.049) in the p.r.n. group. Of the patients in the p.r.n. group who had received regular nebulized therapy on previous admissions (n=12), all preferred the p.r.n. regimen. Prescribing beta2-agonists on a p.r.n. basis from 24 h after hospital admission is associated with reduced amount of drug delivered, incidence of side-effects, and possibly length of hospital stay. This has implications for the efficient use of healthcare resources.

Acute Disease↗
PubMed1999

The long-acting beta2-agonist salmeterol xinafoate: effects on airway inflammation in asthma.

Salmeterol xinafoate is an inhaled long-acting beta2-adrenoceptor agonist recently introduced for the treatment of asthma. Both in vitro and animal studies suggest that it may have anti-inflammatory activities of benefit in this disease. To assess this directly, the effects of 6 weeks' treatment with salmeterol on indices of clinical activity, airway dysfunction and inflammation in subjects with stable atopic asthma were investigated. In a double blind study, asthmatic patients were randomized to 6 weeks' treatment with either salmeterol 50 microg twice daily (n=14) or placebo (n=12). They underwent bronchoscopy with bronchoalveolar lavage (BAL) and bronchial biopsy immediately before starting treatment and again after 6 weeks. Treatment with salmeterol improved clinical indices of asthma activity, but there were no changes in BAL differential cell counts or mediator levels, and no change in T-cell numbers or activation status. In the biopsy specimens there were no changes in numbers of inflammatory cells, sub-basement membrane collagen deposition or mast cell degranulation. Regular treatment with salmeterol improves clinical indices of asthma but has no effect on the underlying inflammatory process. These findings strengthen guideline recommendations that long-acting beta2-agonists should not be prescribed as sole antiasthma medication.

Adolescent↗
PubMed1999

Mucosal inflammation in severe glucocorticoid-dependent asthma.

To improve our understanding of the inflammatory mechanisms underlying severe disease, a biopsy study was performed comparing 15 clinically unstable glucocorticoid-dependent asthmatics, 10 mild asthmatics, and 10 control subjects. Compared with mild asthma, severe asthma was characterized by reduced mucosal eosinophilia. Whilst no significant differences were found in the numbers of mast cells, neutrophils, CD3+ and CD4+ T-cells between the three groups, up to a 4-fold increase In the numbers of activated T-lymphocytes bearing the interleukin (IL)-2 receptor (IL-2R) was found in the mucosa in severe asthma compared to mild asthma (p = 0.03) and control subjects (p = 0.003). Compared to control subjects, the mucosa of severe asthmatics contained significantly (p = 0.02) higher numbers of IL-5+ cells, with no differences between mild and severe disease. In contrast, staining for the anti-IL-4 monoclonal antibody 3H4 revealed that biopsies from mild asthmatics contained more IL4+ cells than biopsies from severe asthmatics and control subjects (p = 0.0008). In the severe asthmatics, a close correlation (r(s) = 0.76, p = 0.005) was found between the numbers of IL-2R-bearing cells and the variability in peak expiratory flow. In conclusion, persistent T-cell activation is a prominent feature of severe asthma. These results also indicate that interleukin-5, and not interleukin-4, is upregulated in severe disease.

Administration, Topical↗
PubMed1998

Human mast cells express stem cell factor.

Stem cell factor (SCF) is a major cytokine regulator of mast cell growth and function. The present study demonstrates that human mast cells are able to produce SCF. Constitutive synthesis of SCF mRNA was seen in the mast cells isolated from human lung and skin by RT-PCR. This was confirmed by in situ hybridization in conjunctival mast cells of both tryptase-only (MCT) and tryptase/chymase (MCTC) subsets. SCF protein product was found in conjunctival MCT and MCTC mast cells by immunohistochemistry. Soluble SCF protein was detected in the culture supernatant of isolated lung mast cells by ELISA, and cross-linkage of IgE receptor (Fc epsilon-RI) on the lung mast cells in culture did not alter SCF mRNA expression, or the secreted soluble SCF protein. This was consistent with the finding that levels of SCF mRNA expression in conjunctival mast cells were similar between normal subjects and patients with seasonal allergic conjunctivitis (SAC). This study shows that human mast cells themselves are a cellular source of SCF, as well as being target cells for this growth factor. SCF may regulate mast cell growth and function via both paracrine and autocrine mechanisms. The production of SCF by mast cells may be regulated via mechanisms other than IgE receptor-mediated pathways.

Cell Culture Techniques↗
PubMed1996

Leukotriene antagonists and synthesis inhibitors: new directions in asthma therapy.

This article briefly reviews the advances in our understanding of asthma with a particular focus on the role of inflammation, before providing a concise overview of current knowledge of leukotrienes in the pathophysiology of the disease. The development of leukotriene receptor antagonists and synthesis inhibitors in briefly described; and acute exercise, allergen, and aspirin challenge studies with these agents are reviewed. Clinical studies with leukotriene antagonists and inhibitors have confirmed the central role of leukotrienes in asthma pathophysiology. In conclusion, we suggest that the new generation of leukotriene receptor antagonists may be suitable as first-line therapy in patients with mild to moderate asthma. Further studies are required to determine whether the leukotriene synthesis inhibitors will be equally effective or provide any additional antiinflammatory benefit.

Anti-Asthmatic Agents↗
PubMed1996

Effect of natural allergen exposure during the grass pollen season on airways inflammatory cells and asthma symptoms.

BACKGROUND: Bronchial challenge with allergen causes a specific form of airways inflammation consisting of an influx of neutrophils, eosinophils, and T cells. Because the relevance of the challenge model to clinical asthma is uncertain, the cellular changes that occur in the lungs of asthmatic subjects during natural seasonal allergen exposure were investigated. METHODS: Seventeen grass pollen sensitive asthmatic subjects with previously reported seasonal exacerbations of asthma kept records of symptoms and underwent fibreoptic bronchoscopy with bronchoalveolar lavage (BAL) and endobronchial biopsy before and during the peak of the grass pollen season. The BAL cells were analysed for differential cell counts and by flow cytometry for T cell subsets and surface activation markers. The biopsy samples were processed into glycol methacrylate resin and immunohistochemical analysis was performed for mast cells, activated eosinophils, T cells and interleukin 4 (IL-4), a cytokine with a pivotal role in allergen-induced inflammation. RESULTS: In the pollen season there was an increase in T lymphocyte activation in the BAL fluid as identified by increased expression of interleukin 2 receptor (IL-2R). In the submucosa these changes were paralleled by an increase in CD4+ T cells. By contrast, the numbers of metachromatic cells in BAL fluid staining with toluidine blue were reduced, possibly because of degranulation following allergen stimulation. In keeping with mast cell activation, the number of mucosal mast cells staining for secreted IL-4 increased during the season. In comparison with the period shortly before the onset of the season, all but two subjects experienced an asthma exacerbation which followed the rise in pollen counts but, compared with the period preceding the first bronchoscopic examination, asthma symptoms were not increased during the pollen season. CONCLUSIONS: The data suggest that natural allergen exposure, leading to a clinical exacerbation of asthma, may induce an inflammatory response involving T cells, mast cells and eosinophils. The relationship between allergen exposure, cellular infiltration and activation, and clinical symptoms appears to be complex, with factors other than allergen also contributing to asthmatic activity.

Adult↗
PubMed1996

Expression of CD44 and integrins in bronchial mucosa of normal and mildly asthmatic subjects.

We have investigated the expression of cell surface markers and leucocyte cell adhesion molecules by immunohistochemistry in bronchial biopsies from 10 mild atopic asthmatics and 8 normal, nonatopic subjects. Significantly increased numbers of eosinophils (p<0.01) were evident in the bronchial submucosa of asthmatic subjects. In epithelium there were more CD44+ (p<0.02) and lymphocyte function-associated antigen-1 (LFA-1)+ (p<0.06) leucocytes in asthmatics than in normal subjects. Bronchial epithelial cells stained positively with anti-CD44 monoclonal antibodies (moAb) in both groups; however, when the staining was expressed as percentage of the total basement membrane, a considerable and highly significant increase was observed in the asthmatics (median 80 vs 22%, p=0.003). Few leucocytes were positive for very late activation antigen (VLA)-1, VLA-2 and VLA-4. The moAb for VLA-6 stained the basement membrane of the bronchial epithelium; while intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were constitutively expressed in endothelium. A positive correlation was found between LFA-1+ cells and activated eosinophils (EG2+) in the submucosa (p<0.005; r(s)=0.80). We conclude that even in mild asthma there is evidence of increased expression of cell surface ligands, and suggest that adhesive mechanisms play a role both in cell recruitment and disease activity.

Adult↗
PubMed1996

Dendritic cells in normal and asthmatic airways: expression of the alpha subunit of the high affinity immunoglobulin E receptor (Fc epsilon RI -alpha).

BACKGROUND: Immunoglobulin E (IgE) plays an important role in asthma, with total serum IgE levels closely related to both clinical expression of the disease and airway hyperresponsiveness. IgE binds to a high affinity cell-surface receptor (Fc epsilon RI) which is present on mast cells and which has also recently been demonstrated on cutaneous dendritic cells. If pulmonary dendritic cells were also able to express this receptor, this would have important implications with regard to their potential role in asthma. OBJECTIVES: The aims of the study were to investigate the expression of the alpha subunit of the high affinity IgE receptor (Fc epsilon RI-alpha) in normal and asthmatic airways, and to analyse its cellular provenance with particular emphasis on the dendritic cell. METHODS: Bronchial biopsy specimens were obtained using fibreoptic bronchoscopy from 10 atopic asthmatics and nine non-atopic non-asthmatic control subjects. Specimens were processed into glycolmethacrylate resin and analysed by immunohistochemistry using specific monoclonal antibodies against Fc epsilon RI-alpha, and against tryptase and CD1a, markers for mast cells and dendritic cells, respectively. RESULTS: The numbers of dendritic cells were significantly higher in the airways of asthmatics compared with those of control subjects (P < 0.02). Analysis of sequential sections revealed that the alpha subunit of Fc epsilon RI was localized to both mast cells and dendritic cells. The proportion of dendritic cells expressing Fc epsilon RI-alpha was significantly increased in the asthmatic group (P < 0.003). CONCLUSION: These results support the hypothesis that dendritic cells play an important role in allergic asthma although the functional significance of Fc epsilon RI-alpha expression needs further investigation.

Adult↗