PubMed Health⌕ Search

Biomedical subjects

P Bradding

Publications and source records attributed to P Bradding.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1995

IgE-dependent expression of mRNA for IL-4 and IL-5 in human lung mast cells.

By using the reverse transcriptase (RT)-PCR and in situ hybridization we have studied the expression of mRNA for IL-5 and IL-4 in human lung mast cells induced by cross-linkage of high affinity Fc epsilon Rs. Lung mast cells were purified using affinity magnetic selection with mAb YB5.B8 against c-kit to achieve a final mast cell purity > 93%. Purified mast cells were precultured with stem cell factor (SCF) (10 ng/ml) and myeloma IgE (3 micrograms/ml) for 16 h before challenge with anti-IgE (1 or 10 micrograms/ml). IgE-dependent activation of lung mast cells caused expression of IL-5 mRNA, which was evident by 2 h and persisted for up to 48-72 h in all of 12 experiments, whereas IL-4 mRNA expression was of a shorter duration and was demonstrable in 6 of 13 experiments. We confirmed that mast cells, and not T cells, were the source of these cytokine messages by using reverse transcriptase-PCR in cell preparations containing known numbers of mast cells and T cells, in situ hybridization in enriched mast cell preparations, and double in situ hybridization-immunocytochemical staining. IL-5 mRNA expression did not require the pretreatment of cells with SCF, whereas expression of IL-4 mRNA seemed to require both anti-IgE and SCF. The strength of IL-5 mRNA signal was related to anti-IgE concentration. Immunoreactive IL-5 was detectable 8 h after anti-IgE challenge, and 10(6) mast cells generated a mean of 731 +/- 400 pg of IL-5 into the supernatant during 48-h culture, but no IL-4 product was detectable. These findings demonstrate the capacity of human lung mast cells to transcribe IL-4 and IL-5 after IgE-dependent activation and to synthesize and release immunoreactive IL-5.

Base Sequence↗
PubMed1995

Heterogeneity of human mast cells based on cytokine content.

Human mast cells can be divided into two distinct phenotypes based on their content of neutral serine proteases, suggesting that they serve differing biologic and pathologic roles. Recently, it has been demonstrated that human mast cells are a source of several pleiotropic cytokines including IL-4, IL-5, IL-6, IL-8, and TNF-alpha, but not all mast cells contain all of these cytokines, suggesting that there is also functional heterogeneity with respect to cytokine expression. In this study, we have examined the relationship between mast cell neutral protease expression and cytokine content using immunohistochemistry. Bronchial mucosal biopsies from five normal subjects and five patients with allergic asthma, and nasal mucosal biopsies from five normal subjects and three patients with allergic rhinitis were embedded in glycol methacrylate. Sections (2 microns) were stained for IL-4, IL-5, and IL-6, adjacent to serial sections stained for tryptase and chymase. The distribution of cytokines among the tryptase+ chymase- mast cells (MCT) and tryptase+ chymase+ mast cells (MCTC) was examined by co-localization of cytokines to MCTC or MCT in serial sections using the camera-lucida. Although IL-4 was distributed among both mast cell phenotypes, it was expressed preferentially by the MCTC subset (overall 85% MCTC:15% MCT). In contrast, IL-5 and IL-6 were restricted almost exclusively to the MCT subset. Immunostaining of isolated skin mast cells (> 99% MCTC) supported these findings, with strong immunoreactivity present for IL-4 but very little for IL-5 or IL-6. These results indicate that in addition to exhibiting heterogeneity with respect to neutral protease content of the secretory granules, human mast cells are also heterogeneous with respect to cytokine content. This suggests that the biologic functions of MCTC and MCT cells differ as a result of their capacity to generate and release different cytokine profiles.

Adult↗
PubMed1995

TNF alpha is localized to nasal mucosal mast cells and is released in acute allergic rhinitis.

Allergic mucosal inflammation is characterized by tissue infiltration with eosinophils, and associated activation of mast cells and T lymphocytes. Tumour necrosis factor (TNF) alpha/cachectin is a candidate cytokine relevant to the pathogenesis of these events through its capacity to upregulate the expression of endothelial cell adhesion molecules, mediate granulocyte chemoattraction, and activate eosinophils, mast cells and T cells. To investigate the presence and localization of TNF alpha in the nasal mucosa in allergic rhinitis, nasal biopsies from perennial rhinitic (n = 13) and non-rhinitic volunteers (n = 11) were embedded in glycol methacrylate and immunostained with a monoclonal antibody directed against TNF alpha, and adjacent 2 microns sections stained for tryptase, CD3 and eosinophil cationic protein. This identified positive immunostaining for TNF alpha in the submucosa of both the rhinitic and normal subjects (median cell counts 13 and 23 cells/mm2 respectively, P = 0.24) with cellular localization to mast cells but not to T-lymphocytes or eosinophils. In a subsequent study of seven atopic subjects, nasal allergen challenge produced increases in lavage levels of histamine and albumin, which was associated with significant release of TNF alpha as early as 2 min post-allergen when compared with the saline control day (P = 0.05). This difference was also apparent when studying the area under the curve both at 30 and 60 min post-challenge t-test (P = 0.015 and 0.02 respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Cytokine immunoreactivity in seasonal rhinitis: regulation by a topical corticosteroid.

Seasonal allergic rhinitis is characterized by the development of nasal mucosal inflammation in response to natural allergen exposure, and is prevented by the administration of topical corticosteroids. Interleukin-4 (IL-4), IL-5, and IL-6 may have important roles in this process, and in vitro the gene transcription for each of these cytokines is inhibited by corticosteroids. In this study we have therefore investigated the effect of seasonal allergen exposure on the expression of immunoreactivity for IL-4, IL-5, and IL-6 in nasal mucosal biopsies, and the effect of regular prophylactic treatment with the topical corticosteroid, fluticasone propionate. Following a nasal mucosal biopsy out of season, patients were randomized double-blind to receive 6 wk of treatment during the pollen season with either topical fluticasone nasal spray (200 micrograms daily) or matching placebo. Each subject underwent a repeat nasal biopsy at the end of the 6-wk treatment period. Seasonal increases in epithelial eosinophils (p = 0.046), submucosal eosinophils (p = 0.001), and epithelial mast cells (p = 0.055) occurred in the placebo--but not the fluticasone-treated patients. Submucosal mast cell numbers did not change in either group. Immunoreactivity for IL-4 and IL-6 was localized predominantly to mast cells while IL-5 was found in both mast cells and eosinophils. Numbers of IL-4+ cells in the nasal submucosa were significantly suppressed by treatment with fluticasone (p = 0.0003 for monoclonal antibody [mAb] 3H4, p = 0.041 for mAb 4D9). In contrast, fluticasone treatment failed to influence the number of IL-5 and IL-6 immunoreactive cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Intranasal↗
PubMed1995

15-lipoxygenase immunoreactivity in normal and in asthmatic airways.

Products of the 15-lipoxygenase (15-LO) pathway of arachidonic acid metabolism such as the mono- and di-hydroxyeicosatetraenoic acids (HETEs) may contribute to the pathophysiology of allergic airway inflammation through the recruitment and activation of inflammatory cells and stimulation of glandular secretion. In this study we have examined the expression of 15-LO and its cellular localization in the asthmatic and normal bronchial mucosa. Bronchial mucosal biopsies were obtained by fiberoptic bronchoscopy from 10 patients with symptomatic allergic asthma and six normal control subjects and processed into glycolmethacrylate resin. Sections 2 microns thick were immunostained using a specific rabbit polyclonal antihuman 15-LO antibody. Strong immunoreactivity for 15-LO was present throughout the epithelium in both the asthmatic and the normal subjects, with no difference between the two groups. Cells expressing 15-LO immunoreactivity were also present in the submucosa of both groups, with a significantly greater number present in the asthmatic group (median, 15.3 cells/mm2) than in the normal group (median, 6.9 cells/mm2) (p = 0.01). The majority (85%) of the submucosal 15-LO+ cells were eosinophils. Patchy 15-LO immunoreactivity was also seen in the vascular endothelium in both groups. These findings demonstrated increased 15-LO expression in the bronchial submucosa of asthmatic subjects, and they suggest that 15-LO products in asthma originate from both bronchial epithelium and infiltrating eosinophils.

Adult↗