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Biomedical subjects

W R Roche

Publications and source records attributed to W R Roche.

At least 19 recordsLinked to original sources
PubMed2003

Asthma deaths; persistent and preventable mortality.

Bronchial asthma remains a significant cause of mortality at all ages, despite the increased understanding of its pathogenesis and the range of drugs available for its treatment. Changes in therapeutic management can influence death rates and constant surveillance, combined with high-quality post mortem investigations, is essential. Disease severity, poor disease management and adverse psychosocial circumstances are all risk factors for asthma mortality. Bronchial asthma causes characteristic histological changes in the mucosa of the airways which are present even before the clinical diagnosis of asthma can be made. These include fibrous thickening of the lamina reticularis of the epithelial basement membrane, smooth muscle hypertrophy and hyperplasia, increased mucosal vascularity and an eosinophil-rich inflammatory cell infiltrate. In addition, mucoid plugging of the airway lumen is frequently associated with fatal asthma. The recognition of these changes can allow the diagnosis of asthma to be made for the first time at autopsy, in those cases where asthma goes undiagnosed in life. Acute severe asthma may be accompanied by pneumothorax and surgical emphysema of the mediastinum. Disorders which may mimic asthma include pulmonary embolism, chronic obstructive pulmonary disease and anaphylaxis, but careful post mortem examination and appropriate investigations should reveal the true cause of death.

Asthma↗
PubMed2002

Immunohistochemistry in the distinction between malignant mesothelioma and pulmonary adenocarcinoma: a critical evaluation of new antibodies.

AIM: The value of immunohistochemical staining in differentiating between malignant mesothelioma and pulmonary adenocarcinoma was re-examined using newly available commercial antibodies, with the aim of increasing the sensitivity and specificity of diagnosis, and simplifying the antibody panel required. METHODS: Forty one malignant mesotheliomas and 35 lung adenocarcinomas were studied. Commercial antibodies to calretinin, E-cadherin, N-cadherin, surfactant apoprotein A (SP-A), thyroid transcription factor 1 (TTF-1), thrombomodulin, and cytokeratin 5/6 were applied using the streptavidin-biotin-peroxidase complex procedure on formalin fixed, paraffin wax embedded tissue. RESULTS: E-cadherin was expressed in all adenocarcinomas and in 22% of the mesotheliomas. TTF-1 expression was detected in 69% of the adenocarcinomas and none of the mesotheliomas. Positive staining with polyclonal anticalretinin was detected in 80% of the mesotheliomas and 6% of the adenocarcinomas. N-cadherin was expressed in 78% of mesotheliomas and 26% of adenocarcinomas. Thrombomodulin was expressed in 6% of the adenocarcinomas and in 53% of the mesotheliomas. Cytokeratin 5/6 expression was detected in 6% of the adenocarcinomas and 63% of the mesotheliomas. The results were compared with the standard laboratory panel for mesothelioma diagnosis: anticarcinoembryonic antigen (anti-CEA), LeuM1, BerEP4, and HBME-1. CONCLUSION: Of the antibodies used in this study, E-cadherin was 100% sensitive for pulmonary adenocarcinoma and TTF-1 was 100% specific for pulmonary adenocarcinoma. The application of these two antibodies alone was adequate for the diagnosis of 69% of adenocarcinomas and 78% of mesotheliomas. Where TTF-1 is negative and E-cadherin is positive, a secondary panel of antibodies, including BerEP4 and LeuM1 (CD15) and antibodies directed against CEA, calretinin, cytokeratin 5/6, thrombomodulin, and N-cadherin, is required for differentiation between malignant mesothelioma and pulmonary adenocarcinoma.

Adenocarcinoma↗
PubMed2001

Basic fibroblast growth factor in asthma: measurement in bronchoalveolar lavage fluid basally and following allergen challenge.

Airway remodeling in asthma refers to a collection of chronic structural changes including subepithelial fibrosis, airway smooth muscle hypertrophy/hyperplasia, and possibly angiogenesis. The mechanisms leading to remodeling are not well defined. One molecule of possible relevance is basic fibroblast growth factor (bFGF), which is a potent mitogen for fibro-blasts, airway smooth muscle cells, and endothelial cells. To test the hypothesis that bFGF expression is increased in asthma, we measured levels of the growth factor in bronchoalveolar lavage (BAL) fluid. Basally, BAL fluid bFGF concentrations were significantly higher in subjects with atopic asthma than in control subjects without asthma (median 0.22 vs 0.06 pg/mL, P = .003). The effect of acute allergen exposure was examined with a segmental bronchoprovocation model in a separate group of subjects with atopic asthma. Ten minutes after segmental bronchoprovocation there was a 5-fold increase in bFGF levels in BAL fluid recovered from allergen-challenged sites compared with control saline-challenged sites (1.52 vs 0.30 pg/mL, P < .002). We conclude that basal levels of BAL fluid bFGF are increased in atopic asthma and that a further increase occurs in response to acute allergen exposure. These findings lend support to the hypothesis that bFGF is implicated in airway remodeling in asthma.

Adult↗
PubMed2001

The relative contribution of mast cell subsets to conjunctival TH2-like cytokines.

PURPOSE: To investigate the distribution of the T-helper (TH)2-like cytokines, interleukin (IL)-4, IL-5, IL-6, and IL-13 between mast cell subsets in conjunctival biopsy specimens from normal subjects and those with seasonal allergic conjunctivitis (SAC) during and outside of the grass pollen season. METHODS: Sequential and double in situ hybridization (ISH) and immunohistochemistry (IHC) were performed on thin sections of human conjunctiva to determine the colocalization of the immunoreactivity of IL-4, IL-5, IL-6, and IL-13 to mast cell subsets in normal subjects and subjects with atopy and to detect IL-4 mRNA in conjunctival mast cells. RESULTS: More than 90% of IL-4+-immunoreactive cells were observed to be mast cells in conjunctival biopsy specimens from all patient groups. The majority of IL-5+, IL-6+, and IL-13+ cells were also noted to be mast cells for each group. IL-4 preferentially colocalized to the tryptase+-chymase+ mast cell phenotype (MC(TC)) with MC(TC) cells comprising 93.3% of cytokine+ mast cells in symptomatic SAC (P = 0.0017), 89.2% in asymptomatic SAC (P = 0.0008), and 77.8% in normal subjects (P = 0.0472). IL-13 appeared to colocalize preferentially to the MC(TC) phenotype and IL-5 and IL-6 to the MC(T) phenotype. ISH showed that 75.8% of mast cells in normal subjects, 78.7% in subjects with symptomatic SAC, and 18.7% in subjects with asymptomatic SAC expressed mRNA for IL-4. CONCLUSIONS: Conjunctival mast cells are an important source of IL-4, IL-5, IL-6, and IL-13 immunoreactivity, with preferential colocalization of IL-4 and IL-13 on the MC(TC) subset and IL-5 and IL-6 to the MC(T) subset. This evidence suggests that differences in protease phenotype may also reflect functional differences evidenced by the different patterns of cytokine distribution.

Adult↗
PubMed2000

Issues in understanding childhood asthma.

Asthma and related allergic disorders in childhood have increased considerably in prevalence over the last few decades. During the same period of increasing morbidity from childhood asthma in the community, there have been dramatic advances in understanding of the basic immunopathologic features of the disease and consequently the development of a far more rational approach to its treatment. The immunopathologic condition of eosinophil-mediated airway inflammation is established very early in the evolution of asthma in childhood. It may even antedate the onset of symptoms. The present state of the art dictates that early intervention with potent therapies cannot be justified on the basis of symptoms alone and may in any case have no influence on the natural history of the condition. This means that current cautious therapeutic guidelines should continue to be followed. However, with the development of more accurate markers predicting ongoing disease, it will be possible to evaluate a whole range of early interventions in the future. Much evidence, though indirect, points to the possibility that the only true prophylaxis that will affect the natural history of asthma will need to be commenced before clinical features are manifest.

Asthma↗
PubMed2000

Progression from allergic sensitization to asthma.

Asthma is one of the atopic diseases strongly associated with allergy. High aeroallergen exposure in the immediate postnatal period has been associated with higher risk of sensitization and chronic asthma. It is proposed that following in utero allergen sensitization, postnatal high dose allergen exposure localizes inflammation to the airways. In association with adjuvantizing effects of some virus infections, eosinophils and neutrophils are recruited which contribute to epithelial damage and the initiation of the remodelling process. Eventually, the latter processes lead to sufficient airway narrowing to manifest as the first symptoms of asthma. Thus, the immunopathology of asthma is fully established by the time of first symptoms and future strategies will need to identify those at risk of developing the disease before irreversible changes in the airways are established.

Allergens↗
PubMed1999

The bronchial epithelium as a key regulator of airway inflammation and remodelling in asthma.

While asthma is an inflammatory disorder of the airways involving mediator release from mast cells and eosinophils and orchestrated by T cells, inflammation alone is insufficient to explain the chronic nature of the disease and its progression. Evidence is presented that the epithelium is fundamentally disordered in chronic asthma manifest by increased fragility, and an altered phenotype to one that secretes mucus, mediators, cytokines, chemokines and growth factors. Epithelial injury is mediated by exogenous factors such as air pollutants, viruses and allergens as well as by endogenous factors including the release of proteolytic enzymes from mast cells (tryptase, chymase) and eosinophils (MMP-9). Following injury, the normal epithelium should respond with increased proliferation driven by ligands acting on epidermal growth factor (EGF) receptors or through transactivation of the receptor. The epithelial response to these stimuli in asthma appears to be impaired despite upregulation of CD44 capable of enhancing presentation of EGF ligands to epidermal growth factor receptors (EGFR). Because the epithelium is 'held' in this repair phenotype, it becomes a continuous source of proinflammatory products as well as growth factors that drive airway wall remodelling.

Animals↗
PubMed1999

Growth factors secreted by bronchial epithelial cells control myofibroblast proliferation: an in vitro co-culture model of airway remodeling in asthma.

Remodeling of the bronchial wall is a major determinant of morbidity in asthma. An increased number of myofibroblasts beneath the bronchial epithelial basement membrane has been described in asthma. The production of mediators by epithelial cells in close proximity to myofibroblasts during epithelial repair after repeated damage is one of the possible mechanisms for airway remodeling. In this study, we established a three-dimensional co-culture system in which myofibroblasts derived from human bronchial wall were maintained in collagen gels and a human bronchial epithelial cell line, 16HBE14o-, was grown on the surface of the gels. The epithelial cells were chemically injured by exposure to poly-L-arginine as a surrogate for eosinophil granule cationic protein and the proliferative response of the fibroblasts was examined. Conditioned medium from mechanically damaged epithelial cells was also tested for its effect on fibroblast proliferation. Myofibroblasts in the co-cultures showed significantly enhanced proliferation after poly-L-arginine-induced epithelial damage. Conditioned medium from mechanically damaged epithelial cells also increased fibroblast-proliferation. After epithelial perturbation, basic fibroblast growth factor, platelet-derived growth factor, IGF-1, transforming growth factor-beta2, and endothelin-1 levels increased in culture supernatants. Blockade of these growth factors inhibited fibroblast proliferation by 76% after epithelial injury. This study demonstrates that epithelial cells are an important regulator of airway remodeling by means of paracrine control of bronchial myofibroblasts in response to cell damage and repair.

Asthma↗
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↗
PubMed1998

Co-localization of immunoreactive transforming growth factor-beta 1 and decorin in bronchial biopsies from asthmatic and normal subjects.

Airway wall remodelling is an established pathological feature of asthma but its causes are not well understood. One cytokine of potential relevance is transforming growth factor-beta1 (TGF-beta 1). The immunolocalization of TGF-beta 1 and of its small binding proteoglycan decorin have been examined in the airways of normal subjects and atopic asthmatics. Bronchial biopsy specimens were obtained by fibreoptic bronchoscopy, processed into glycolmethacrylate resin, and stained immunohistochemically using specific antibodies. Immunoreactive TGF-beta 1 was principally localized extracellularly in association with subepithelial connective tissue. Some staining of bronchial epithelial cells was also evident, but otherwise there was little intracellular staining. The overall pattern of immunohistochemical staining was indistinguishable in biopsy specimens from asthmatic and control subjects. Comparison of adjacent sections demonstrated the co-localization of immunoreactivity for TGF-beta 1 and decorin in the mucosa. It is concluded that immunoreactive TGF-beta 1 in human airways is principally extracellular and that matrix-associated TGF-beta 1 is likely to be bound at least in part to decorin. This interaction may provide a reservoir of TGF-beta 1 that can be released in an active form in response to appropriate stimuli.

Adult↗
PubMed1998

Inflammatory mechanisms in childhood asthma.

There is now a reasonable body of data that would suggest that the immunopathology of asthma is similar, if not identical, in childhood asthmatics compared with adult asthmatics. Indeed, we now have evidence that much of the immunopathology is established within the airways of asthmatics very early after the onset of symptoms and, given the lack of correlation with duration of symptoms, may even antedate the first manifestations. There are, however, some differences with neutrophil recruitment being somewhat more prominent than has been recorded from adult observations. The utility of any inflammation parameter in identifying the real future asthmatics has yet to be studied in sufficient detail to define sensitivity, specificity and predictive value. Such studies will be an essential prerequisite to establishing very early intervention strategies, particularly if these involve the use of inhaled and/or oral corticosteroid.

Adult↗
PubMed1997

Seasonal allergic conjunctivitis is accompanied by increased mast cell numbers in the absence of leucocyte infiltration.

BACKGROUND: Seasonal allergic conjunctivitis (SAC) is the most common allergic disease to affect the eye, occurring alone or in association with allergic rhinitis. Infiltration with mast cells and eosinophils is characteristic of the chronic forms of allergic conjunctivitis such as vernal and atopic keratoconjunctivitis, and these cell types also contribute significantly to allergic inflammation in the skin. Indirect evidence for a similar pattern of cellular events in SAC comes from studies which demonstrate raised eosinophil and neutrophil numbers in conjunctival scrapings and elevated levels of mast cell tryptase in tears following allergen challenge. OBJECTIVE: To directly characterize the inflammatory cell infiltrate in SAC and to determine its clinical relevance. METHODS: We employed specific immunohistochemical staining to count mast cells, eosinophils and neutrophils in the conjunctival epithelium and lamina propria of eight atopic patients with SAC in, and 12 SAC patients out of the hay fever season. Sixteen patients with no history of ocular allergy were used as control subjects. RESULTS: Mast cells were absent from normal epithelium. During the pollen season median mast cell numbers in the lamina propria were found to be increased by 61% in patients with SAC compared with normals (P=0.012). Eosinophils were found in the lamina propria in less than half of the symptomatic patients with SAC and in only three patients were eosinophils present in the epithelium. The neutrophil numbers in the lamina propria of patients with SAC tended to be higher than normals but these changes did not reach statistical significance. CONCLUSION: These data based on the direct assessment of conjunctival tissue provide evidence that symptoms occur in SAC in the absence of detectable recruitment of eosinophils or neutrophils. This suggests that this disorder is related to mast cell-mediated changes.

Adult↗
PubMed1997

Transforming growth factor-beta 1 in asthma. Measurement in bronchoalveolar lavage fluid.

Airway wall remodeling is an established pathological feature in asthma. Its causes are not well understood, but one mediator of potential relevance is transforming growth factor-beta 1 (TGF-beta 1). We have measured levels of immunoreactive TGF-beta 1 in bronchoalveolar lavage (BAL) fluid from clinically stable atopic asthmatics and healthy control subjects. We have also examined the influence of allergen exposure on TGF-beta 1 release in the airways using a segmental bronchoprovocation model, with BAL performed at two time points following endobronchial allergen and sham saline challenges. Basal concentrations of TGF-beta 1 were significantly higher in asthmatics than control subjects (median 8.0 versus 5.5 pg/ml, p = 0.027). Following segmental bronchoprovocation, concentrations of TGF-beta 1 at the allergen- and saline-challenged sites were not significantly different after 10 min, (31.3 versus 25.0 pg/ml, p = 0.78), but after 24 h there were significantly higher TGF-beta 1 concentrations at the allergen-challenged sites (46.0 versus 21.5 pg/ml, p = 0.017). We conclude that basal TGF-beta 1 levels in the airways are elevated in atopic asthma and that these levels increase further in response to allergen exposure. These findings are consistent with the hypothesis that TGF-beta 1 is implicated in airway wall remodeling in asthma.

Adult↗
PubMed1997

Immunolocalization of cytokines to mast cells in normal and allergic conjunctiva.

BACKGROUND: Recently, the potential role of mast cells in allergic reactions has been extended by the discovery that these cells synthesize, store and secrete multifunctional cytokines. Seasonal allergic conjunctivitis is characterized as an immediate hypersensitivity reaction, in which allergen binds to specific IgE on mast cells, leading to release of pre-formed and newly synthesized inflammatory mediators. OBJECTIVE: In this study we aimed to localize the cytokines IL-4, IL-5, IL-6, IL-8 and TNF alpha to conjunctival mast cells and to examine the relationship between mast cell-associated cytokines and allergic conjunctivitis. METHODS: Immunohistochemistry was performed on serial sections of conjunctival biopsies from patients with seasonal allergic conjunctivitis, in and out of the hay fever season, as well as from non-allergic volunteers. RESULTS: IL-4, IL-5, IL-6 and TNF alpha were localized to mast cells in normal and allergic conjunctiva. IL-8 was localized to mast cells in two patients with seasonal allergic conjunctivitis, one during and the other outside the pollen season. Using the monoclonal antibody 3H4, which identifies the secreted form of IL-4, biopsies from patients with active seasonal allergic conjunctivitis contained a significantly higher proportion of mast cells positive for IL-4, than those from out-of-season patients (P=<0.016). There was no difference between the two groups in the number of mast cells immunostained by the antibody 4D9 which identifies the stored form of IL-4. CONCLUSIONS: These results suggest that conjunctival mast cells can store a range of multifunctional cytokines and release IL-4 during active disease, which may give them an important role in upregulating allergic inflammation in the conjunctiva.

Adult↗
PubMed1996

Cytokine production by cell cultures from bronchial subepithelial myofibroblasts.

Myofibroblasts have been previously described beneath the bronchial epithelium and were found to increase in number proportional to the accumulation of extracellular matrix in the bronchial lamina reticularis in asthma. The aim of this study was to assess further the contribution of these structural cells to allergic inflammation in the bronchial mucosa through their cytokine expression. Cell cultures were established from the lamina reticularis of human bronchial biopsies from asthmatic and non-asthmatic subjects. Cytokine secretion was measured by ELISA in supernatants of cultures with or without tumour necrosis factor-alpha (TNF-alpha). The mRNA levels for granulocyte-macrophage colony-stimulating factor (GM-CSF) in the cultures were examined by ribonuclease protection assays (RPAs). Bronchial myofibroblasts grown from bronchial biopsies were capable of producing GM-CSF, interleukin-6 (IL-6), interleukin-8 (IL-8), and stem cell factor (SCF) constitutively. The GM-CSF production by myofibroblasts was significantly increased in response to TNF-alpha simulation with a corresponding increase in GM-CSF mRNA expression. The enhancement of GM-CSF production by TNF-alpha in myofibroblasts was blocked by the inhibition of RNA synthesis. Prednisolone abolished the GM-CSF production. This study provides evidence for the role of bronchial myofibroblasts in the regulation of inflammatory cell recruitment and activation by interaction in the cytokine network in the bronchial mucosa.

Asthma↗