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Biomedical subjects

Stephen T Holgate

Publications and source records attributed to Stephen T Holgate.

At least 91 records · Page 5Linked to original sources
PubMed2002

Rhinovirus infection increases 5-lipoxygenase and cyclooxygenase-2 in bronchial biopsy specimens from nonatopic subjects.

Rhinovirus infections cause wheeze, cough, and bronchial hyperresponsiveness. To investigate the involvement of cysteinyl-leukotrienes and prostanoids in these symptoms, bronchial biopsy specimens from 9 normal subjects (nonatopic and with no history of chronic lung disease) were immunostained for 5-lipoxygenase (5-LO) and cyclooxygenase (COX) pathway enzymes 2 weeks before and 4 days after experimental infection with human rhinovirus serotype 16. 5-LO-positive cell counts increased 9-fold (from 0.48 to 4.4 cells/mm(2); P <.05), and 5-LO-activating protein (FLAP)-positive cell counts increased 3.6-fold (from 1.8 to 6.5 cells/mm(2); P =.09). Levels of leukotriene A(4) hydrolase and leukotriene C(4) synthase were unchanged. COX-2--positive cell counts increased from 0 to 2.6 cells/mm(2) (P =.009), with no change in COX-1 levels. Increases of 3-4-fold were seen in levels of macrophages (P =.02) and mast cells (P =.07) but not of eosinophils (P >.4), and bronchoalveolar lavage fluid cysteinyl-leukotriene levels doubled (from 11.2 to 20.4 pg/mL; P =.13). Cold symptom scores correlated with bronchial immunostaining for FLAP (rho = 0.93; P =.001). In normal subjects, rhinovirus colds induce bronchial inflammation with markedly enhanced expression of 5-LO pathway proteins and COX-2.

Arachidonate 5-Lipoxygenase↗
PubMed2002

A birth cohort study of subjects at risk of atopy: twenty-two-year follow-up of wheeze and atopic status.

This study describes the natural history of atopic and wheezy disorders from birth to adult life in a cohort at risk of atopy. One hundred subjects born in Poole, England, were selected at birth in 1976 on the basis that at least one parent was atopic. Subjects were examined annually in the preschool years, and at the ages of 11 and 22 yr. Skin prick tests and total serum immunoglobulin E (IgE) were performed at each visit, and at 11 and 22 yr, bronchial hyperresponsiveness (BHR) to inhaled histamine was measured. Sixty-three subjects remained on follow-up at 22 yr. The annual prevalence of both wheeze and atopy increased with age. Twenty-five percent of adults showed both wheeze and BHR (asthma). Remission of wheeze was common in subjects younger than 5 yr of age and likely if wheezing occurred on less than two occasions, but wheeze at 11 yr was likely to persist. Sixty percent of the adult subjects with asthma developed sensitivity to common allergens by the age of 2 yr and were showing BHR by mid-childhood. Sensitization to dietary allergens occurred in infancy and waned after early childhood but predicted the early sensitization to inhalant allergens. In conclusion, adults with asthma can begin wheezing at any age but tend to sensitize early and have abnormal airway characteristics by the age of 11 yr.

Adolescent↗
PubMed2002

Improvement of aspirin-intolerant asthma by montelukast, a leukotriene antagonist: a randomized, double-blind, placebo-controlled trial.

Leukotriene antagonists block the proinflammatory actions of leukotrienes (LT) and have been introduced as new treatments for asthma. Conventional therapy with glucocorticosteroids does not inhibit the biosynthesis of leukotrienes. We therefore tested whether addition of the leukotriene receptor antagonist montelukast was of therapeutic benefit in a group of aspirin-intolerant patients with asthma of whom 90% already were treated with moderate to high doses of glucocorticosteroids. Under double-blind conditions, 80 aspirin-intolerant patients with asthma were randomized to receive 4 wk oral treatment of either 10 mg of montelukast or placebo once daily at bedtime. Pulmonary function was measured as forced expiratory volume in 1 s (FEV(1)) once a week in the clinic and daily as morning and evening peak expiratory flow rate (PEFR). Asthma symptoms and use of rescue bronchodilator were also recorded daily. Asthma specific quality of life (QoL) was assessed before and after the treatments. The group receiving montelukast showed a remarkable improvement of their asthma, whereas the group given placebo showed no change. Thus, from equal baseline values, the mean difference between the groups over the 4-wk treatment period was 10.2% for FEV(1) and 28.0 L for morning PEFR (p for both < 0.001). The improved pulmonary function in the group receiving montelukast occurred at the same time as 27% less bronchodilator was used (p < 0.05), and it was associated with fewer asthma symptoms than in the group given placebo, including 1.3 nights more of sleep per week and 54% fewer asthma exacerbations (p < 0.05). There was also an improvement in asthma-specific QoL (p < 0.05). The therapeutic response to montelukast was consistent across patients with different baseline characteristics and did not correlate with baseline urinary LTE(4). Addition of a leukotriene receptor antagonist such as montelukast improves asthma in aspirin-intolerant patients over and above what can be achieved by glucocorticosteroids.

Acetates↗
PubMed2002

Targeting adenosine receptors: novel therapeutic targets in asthma and chronic obstructive pulmonary disease.

Adenosine, an endogenous signaling nucleoside that modulates many physiological processes has been implicated in playing an ever increasingly important role in the pathogenesis of asthma and chronic obstructive pulmonary disease (COPD). All cells contain adenosine and adenine nucleotides and the cellular production of adenosine is greatly enhanced under conditions of local hypoxia as may occur in inflammatory conditions such as asthma and COPD. In 1983, it was first reported that inhaled adenosine causes dose-related bronchoconstriction in patients with both allergic and non-allergic asthma but not in healthy volunteers. This hyperresponsiveness was also reported in patients with COPD, with those patients who smoked exhibiting a significantly greater response. This bronchoconstrictor effect of adenosine is orchestrated through the stimulation of specific cell membrane receptors and involves an important inflammatory cell, the mast cell. There is substantial evidence which suggests that mast cell activation is central to this unique response to adenosine. Mast cell mediator release makes a significant contribution towards airflow obstruction and the consequent symptoms in patients with asthma. Over the last two decades, researchers have investigated the effect of mast cell inhibitors as well as mast cell mediator receptor antagonists and their role in attenuating the bronchoconstrictor response to inhaled adenosine 5'-monophosphate (AMP). Promising results have been shown using mast cell stabilizers, histamine H1 receptor antagonists, selective cysteinyl leukotriene-1 receptor antagonists and inhibitors of 5-lipoxygenase and cyclo-oxygenase. Through these findings, the mast cell has been recognized as being a critical inflammatory cell in the adenosine-induced response in patients with asthma and COPD. To date, four subtypes (A1, A2A, A2B, A3) of adenosine receptors have been cloned each with a unique pattern of tissue distribution and signal transduction. Activation of these receptors has pro- and anti-inflammatory consequences making the development of agonists and/or antagonists at these receptor sites a novel approach in the treatment of patients with asthma and COPD. This review highlights the importance of adenosine in the pathophysiology of asthma and COPD, the critical role of the mast cell and the potential to target the adenosine receptor subtype in patients with asthma and COPD. The complete characterization of these adenosine receptor subtypes in terms of their distribution in humans and the development of selective agonists and antagonists, holds the key to our complete understanding of the role of this important mediator in asthma and COPD.

Adenosine↗
PubMed2002

Distribution of basement membrane pores in bronchus revealed by microscopy following epithelial removal.

The basement membrane of the bronchial epithelium separates the epithelial and mesenchymal compartments. Basement membrane pores allow cells to cross this boundary. We present a method for preparation of samples of human basement membrane allowing us easy visualisation and characterisation of the distribution and persistence of these pores. Columnar epithelial cells were removed from airway samples with gentle scraping with a circular glass coverslip. In contrast, the underlying basal cells required incubation once in dithiothreitol and twice in ethylenediaminetetraacetic acid. Scanning electron microscopy (SEM) at each stage of the epithelial stripping process showed the selective removal of epithelial cells with eventual visualisation of the pores. Using confocal microscopy on blocks of viable tissue, pores were shown to persist in culture for at least 5 days, despite the presence of viable cells in the submucosa. The distribution of pores in tissues determined by SEM was compared to simulations of three distribution patterns (random, clumped, and distributed). The pattern of pores in the samples was consistent with a random distribution. We suggest that basement membrane pores can be generated by the passage of infiltrating cells into the epithelium providing a network suitable for intraepithelial surveillance.

Basement Membrane↗
PubMed2002

On the generation of allergic airway diseases: from GM-CSF to Kyoto.

The sharp increase in the prevalence of asthma over the past three decades suggests an important contribution of environmental factors in the generation of this disease, and compels a search for molecular pathways by which such factors could facilitate Th2 immune-inflammatory airway responses; granulocyte-macrophage colony-stimulating factor (GM-CSF) might be one such signal. In this review, we appraise the evidence with respect to the presence of GM-CSF in asthma, the roles played by GM-CSF in these immune responses and environmental triggers that can induce GM-CSF expression. Further, we propose a paradigm that unites these divergent observations, and postulate that GM-CSF produced in response to environmental agents can establish an airway microenvironment that promotes the initiation, influences the evolution and supports the maintenance of an aeroallergen-specific adaptive Th2 immune response.

Animals↗
PubMed2002

Expression of c-erbB receptors and ligands in the bronchial epithelium of asthmatic subjects.

BACKGROUND: The c-erbB family of receptor tyrosine kinases act in a combinatorial fashion to regulate cell behavior. Disturbances in this system have been associated with neoplastic and inflammatory diseases. OBJECTIVES: Although expression of the epidermal growth factor receptor (EGFR; c-erbB1) is increased in the bronchial epithelium in asthma, there is no information on expression of other members of the c-erbB receptor and ligand family that can modulate EGFR function. METHODS: Immunohistochemistry was used to compare expression of EGFR, c-erbB2, c-erbB3, epidermal growth factor, heparin-binding epidermal growth factor-like growth factor, and transforming growth factor alpha in bronchial biopsy specimens from normal and asthmatic subjects. Scrape-wounded monolayers of 16HBE 14o(-) cells were used as an in vitro model of damage and repair. Changes in EGFR, c-erbB2, and c-erbB3 distribution were measured by means of immunocytochemistry, whereas tyrosine phosphorylation was measured by means of immunoprecipitation and Western blotting. RESULTS: Although epithelial staining for the EGFR was significantly increased in asthmatic epithelium (P <.001), there was no difference in staining for the other receptors and ligands studied. In scrape-wounded epithelial monolayers, tyrosine phosphorylation of EGFR, c-erbB2, and c-erbB3 occurred immediately after damage; however, only EGFR showed a change in expression in response to damage. CONCLUSIONS: Even though EGFR levels are increased in asthma, this is not linked to changes in expression of its activating ligands or other c-erbB receptors. Because bronchial epithelial cells respond to physical damage through activation of several c-erbB family members, the shift in favor of increased EGFR levels in asthma may lead to altered epithelial function by influencing the number and type of heterodimeric signaling complexes, assuming sufficient ligand availability.

Adult↗
PubMed2002

Differential roles of IL-16 and CD28/B7 costimulation in the generation of T-lymphocyte chemotactic activity in the bronchial mucosa of mild and moderate asthmatic individuals.

BACKGROUND: IL-16 is an important T-cell chemotactic cytokine in asthmatic airways; its release from allergen-stimulated bronchial mucosa in mild asthma has been shown to be dependent on CD28/B7 costimulation. OBJECTIVE: We have extended our previous studies to investigate the role of IL-16 and CD28/B7 costimulation in T-lymphocyte chemotactic activity (TLCA) released from the bronchial mucosa in more severe asthma. METHODS: TLCA was determined in the supernatants of induced sputum and allergen-stimulated bronchial mucosal explants from healthy volunteers and volunteers with mild and moderately severe asthma by means of a Boyden chamber technique. The contribution of IL-16 to the activity was evaluated through use of a neutralizing monoclonal antibody; the contribution of CD28/B7 costimulation to allergen-induced release of TLCA was determined through use of CTLA4-Ig fusion protein and neutralizing monoclonal antibodies to CD80 (B7.1) and CD86 (B7.2). RESULTS: Induced sputum and unstimulated explants from asthmatic subjects generated significant spontaneous TLCA (P <.05). Both mild and moderate asthmatic explants showed significantly elevated Dermatophagoides pteronyssinus -induced release of TLCA, but only in mild asthma could sputum and allergen-stimulated explant TLCA be inhibited by anti-IL-16 (median inhibition, 39% and 59%; P <.05). In addition, allergen released significant quantities of IL-16 from mild asthmatic explants (P <.05) but not from moderate asthmatic explants. Antibodies to the CD28 counter-ligands CD80 and CD86 inhibited allergen-induced release of TLCA in mild asthmatic explants by 94% (P <.05) and 62%, but TLCA release from moderate asthmatic explants was unaffected by CTLA4-Ig. CONCLUSION: These results show that TLCA release in moderate asthmatic airways, in contrast to mild asthmatic airways, is not dependent on CD28/B7 costimulation and does not involve IL-16.

Abatacept↗
PubMed2002

Changes in sputum counts and airway hyperresponsiveness after budesonide: monitoring anti-inflammatory response on the basis of surrogate markers of airway inflammation.

BACKGROUND: Airway hyperresponsiveness (AHR) to pharmacologic stimuli and sputum eosinophils might be useful in the individual adjustment of long-term asthma management. However, it is not clear whether inhaled glucocorticosteroids (GCSs) provide greater protection against specific surrogate markers of airways inflammation than other means. In addition, detailed longitudinal assessment of changes in airway response with inhaled GCSs has never been carried out. OBJECTIVES: We compared changes in AHR to inhaled methacholine and adenosine 5'-monophosphate (AMP) after budesonide treatment in a randomized, double-blind, placebo-controlled, crossover study of patients with mild-to-moderate asthma. Subsequently, we undertook a separate study to examine the time course of the changes in AHR in more detail and the changes in sputum cell counts in relation to budesonide treatment. METHODS: In the phase 1 of the study, patients undertook bronchial provocation studies with increasing doubling concentrations of methacholine (0.06 to 16 mg/mL) and AMP (3.125 to 800 mg/mL) before and after budesonide 0.8 mg/daily for 3 weeks. The bronchial responses to the inhaled agonists were expressed as the provocative concentration causing a 20% decline in FEV(1) (PC(20)). In phase 2 of the study, patients attended the laboratory on 12 separate occasions to investigate changes in PC(20) methacholine, PC(20) AMP, and sputum cell counts before, during, and after withdrawal of therapy with inhaled budesonide 0.8 mg/daily for 6 weeks. RESULTS: Budesonide treatment for 3 weeks significantly attenuated the constrictor response by 0.8 +/- 0.3 doubling doses for methacholine and by 2.6 +/- 0.5 doubling doses for AMP. These changes were significantly different from each other (P =.003). Significant variation in PC(20) methacholine (P <.05) value, PC(20) AMP (P <.001) value, percentage of sputum eosinophils (P <.001), and percentage of sputum epithelial cells (P <.001) were observed throughout the longitudinal assessment of changes in airway response to budesonide. Compared with the other surrogate markers, PC(20) AMP appears to be useful in promptly detecting early inflammatory changes of the asthmatic airways; a significant change of 1.6 +/- 0.3, 2.2 +/- 0.3, and 2.8 +/- 0.3 doubling doses of PC(20) AMP was observed at 1, 4, and 6 weeks, respectively, in the course of budesonide treatment. CONCLUSIONS: The present findings underline the exquisite selectivity of diverse surrogate markers of airway inflammation in response to inhaled budesonide. When compared with that to the other markers, AHR to inhaled AMP is an early and sensitive indicator of the beneficial anti-inflammatory effects of topical GCSs.

Adenosine Monophosphate↗
PubMed2002

TGF-beta isoform release and activation during in vitro bronchial epithelial wound repair.

Restitution of an epithelial layer after environmental or biological damage is important to maintain the normal function of the respiratory tract. We have investigated the role of transforming growth factor (TGF)-beta isoforms in the repair of layers of 16HBE 14o(-) bronchial epithelial-derived cells after damage by multiple scoring. ELISA showed that both latent TGF-beta1 and TGF-beta2 were converted to their active forms 2 h after wounding. Time-lapse microscopy showed that the addition of TGF-beta1, but not TGF-beta2, progressively increased the rate of migration of damaged monolayers at concentrations down to 250 pg/ml. This increase was blocked by addition of a neutralizing TGF-beta1 antibody. Phase-contrast microscopy and inhibition of proliferation with mitomycin C showed that proliferation was not required for migration. These results demonstrate that conversion of latent to active TGF-beta1 and TGF-beta2 during in vitro epithelial wound repair occurs quickly and that TGF-beta1 speeds epithelial repair. A faster repair may be advantageous in preventing access of environmental agents to the internal milieu of the lung although the production of active TGF-beta molecules may augment subepithelial fibrosis.

Antibodies, Monoclonal↗
PubMed2002

Autocrine ligands for the epidermal growth factor receptor mediate interleukin-8 release from bronchial epithelial cells in response to cigarette smoke.

Airway neutrophilia is a prominent feature of chronic obstructive pulmonary disease. As cigarette smoke (CS) and epidermal growth factor (EGF) both cause release of interleukin-8 (IL-8) from epithelial cells in vitro, we investigated whether autocrine ligands for the EGF receptor (EGFR) are involved in this proinflammatory response to CS. NCI-H292 or primary bronchial epithelial cells were cultured with or without cigarette smoke extract (CSE) or EGF for 6-48 h. We then tested culture supernatants for lactate dehydrogenase activity to assess cell viability, and for IL-8 and EGFR ligands by ELISA; quantitative RT-PCR was used to measure IL-8 and EGFR ligand mRNA. EGF and low concentrations of CSE both promoted cell survival and caused enhanced transcription and release of IL-8. Similarly, levels of mRNA encoding transforming growth factor alpha (TGF-alpha), heparin-binding EGF-like growth factor, and amphiregulin (AR) were increased, as was shedding of TGF-alpha and AR protein into the culture medium. With the exception of AR gene transcription, the CS-induced responses were blocked by the EGFR-selective kinase inhibitor AG1478. Furthermore, ~ 45% of CS-induced IL-8 release was inhibited by a neutralising anti-EGFR. Our data indicate that secretion of IL-8 in response to CSE is dependent on EGFR activation and that autocrine production of TGF-alpha makes a substantial contribution to this response.

Adult↗
PubMed2002

Asthmatic bronchial epithelium is more susceptible to oxidant-induced apoptosis.

Abnormal apoptotic mechanisms are associated with disease pathogenesis. Because the asthmatic bronchial epithelium is characteristically damaged with loss of columnar epithelial cells, we postulated that this is due to unscheduled apoptosis. Using an antibody directed toward the caspase cleavage product of poly(ADP-ribose) polymerase, immunohistochemistry applied to endobronchial biopsies showed higher levels of staining in the bronchial epithelium of subjects with asthma as compared with normal control subjects (% epithelial staining [median (range) = 10.5 (1.4-24.5) versus 0.4 (0.0-9.7)]; P < 0.001). Because we were unable to determine whether this difference was due to ongoing inflammation in vivo, cultures of normal and asthmatic bronchial epithelial cells were used to study apoptosis in vitro. In complete growth medium, these cells showed no difference in their rate of proliferation or viability. However, cells from subjects with asthma were more susceptible to the apoptotic effects of H2O2 than cells from normal control subjects (% apoptotic cells = 32.2 [8.8-54.9] versus 14.3 [6.4-24.7]; P < 0.05), even though both were similarly affected by treatment with actinomycin D. These data indicate that the susceptibility of asthmatic bronchial epithelium to oxidants is greater than normal. This susceptibility may contribute to the rising trends in asthma associated with air pollution and diets low in antioxidants.

Adult↗
PubMed2002

The role of anti-IgE therapies in the treatment of asthma.

The prevalence of asthma, a chronic inflammatory disease often linked to allergy, is on the increase. The introduction of a blocking anti-IgE monoclonal antibody (omalizumab) as a new therapy has not only confirmed the pathogenic role of IgE in asthma but has also provided a novel therapy for a chronic severe disease where there are limited therapeutic options.

Antibodies, Anti-Idiotypic↗
PubMed2002

Airway inflammation and remodeling in asthma: current concepts.

Asthma is a chronic inflammatory disorder of the airways interacting with altered structure and function of the formed elements including smooth muscle. While atopy and polarization of the airway T-cell response toward a Th-2 phenotype are important factors in asthma pathogenesis, there is increasing realization that remodeling events are also important. Evidence is presented that inflammation and altered airway structure in asthma interact through the epithelium and underlying mesenchyme. As in other chronic inflammatory disorders, a dynamic interplay between mediators, cytokines, and growth factors provides a broader base on which to identify novel preventative and therapeutic strategies in asthma.

Asthma↗