Biomedical subjects

Gordon Dent

Publications and source records attributed to Gordon Dent.

5 recordsLinked to original sources

PubMed2006

Impaired neutrophil chemotaxis in chronic obstructive pulmonary disease.

RATIONALE: Neutrophilic airway inflammation is considered to be a major factor in the pathogenesis of chronic obstructive pulmonary disease (COPD), with sputum and bronchoalveolar lavage neutrophil counts broadly correlating with disease severity. The mechanisms responsible for neutrophil accumulation are poorly understood, but they could involve increased influx and/or survival of these cells. OBJECTIVES: To investigate whether neutrophil chemotactic responsiveness and/or chemotactic activity in airway secretions are increased in subjects with COPD. METHODS: Chemotaxis experiments were performed using induced sputum supernatants from subjects with and without COPD as a source of chemotactic activity, and neutrophils from healthy donors as responder cells. In addition, chemotactic responses to N-formyl-Met-Leu-Phe (fMLP) and interleukin-8 (IL-8/CXCL8) were studied using neutrophils from healthy subjects and subjects with COPD. MEASUREMENTS AND MAIN RESULTS: As reported in the literature, sputum neutrophil counts were significantly increased in subjects with COPD compared with healthy subjects. However, this was associated with reduced chemotactic activity in sputum in COPD, as judged by reduced chemotaxis to the fluid phase of sputum from subjects with COPD compared with healthy subjects. Furthermore, whereas neutrophils from subjects with stage I COPD had normal responses to fMLP and IL-8, subjects with more severe stage II-IV COPD showed reduced levels of spontaneous migration and chemotaxis to fMLP and IL-8. CONCLUSIONS: Neither increased chemotactic activity in the airways nor increased chemotactic responsiveness of neutrophils explains the increased number of these cells in subjects with stable COPD. The implications of the observed reduction in neutrophil chemotactic activity remain to be established.

Bronchoalveolar Lavage Fluid↗

PubMed2004

Contribution of eotaxin-1 to eosinophil chemotactic activity of moderate and severe asthmatic sputum.

The CC chemokine eotaxin-1 (CCL11) is chemotactic for eosinophils, basophils, and type 2 helper T cells and may play a role in allergic inflammation. We investigated its contribution as an eosinophil chemoattractant in asthmatic airway secretions (sampled as induced sputum), which possess chemotactic activity for eosinophils and T cells. Sputum samples collected from healthy subjects and subjects with mild, stable-moderate, unstable-moderate, and severe asthma were processed with phosphate-buffered saline and assayed for eotaxin by ELISA and for eosinophil chemotactic activity by fluorescence-based chemotaxis assay. The contribution of eotaxin to chemotactic activity was studied by using a high-affinity neutralizing human anti-eotaxin antibody, CAT-213. Sputum eotaxin concentration was significantly raised in moderate and severe asthma (p < 0.05 versus healthy control subjects) but not in mild asthma. Chemotactic activity was significantly increased in all asthmatic groups relative to healthy subjects (p < 0.05) and was significantly inhibited by CAT-213 (100 nM) in subjects with moderate and severe asthma, with median inhibition of 52% (p < 0.05), 78% (p < 0.0001), and 86% (p < 0.0001), respectively, in samples representing stable-moderate, unstable-moderate, and severe asthma. Eotaxin contributed to the eosinophil chemotactic activity of sputum from subjects with more severe forms of asthma but not mild asthma, suggesting that its contribution is more important in more severe disease. This activity is inhibited significantly by CAT-213.

Adult↗

PubMed2004

Measurement of eotaxin (CCL11) in induced sputum supernatants: validation and detection in asthma.

BACKGROUND: Induced sputum is widely used in asthma research; however, for many mediators, the detection methods have not been validated. OBJECTIVE: We sought to optimize the method of detection of eotaxin, an important chemokine acting through the CCR3 receptor on eosinophils, basophils, and T(H)2 cells. METHODS: Induced sputum from normal and asthmatic subjects was processed with dithioerythritol (DTE) or PBS; recovery of eotaxin was assessed by means of ELISA before and after spiking with recombinant eotaxin. Furthermore, the effects of removing DTE by means of ultrafiltration or the addition of protease inhibitors and high-speed centrifugation on endogenous levels and spiking recovery of eotaxin were assessed. RESULTS: Endogenous eotaxin was undetectable in DTE-processed samples, with a mean of only 30% (SD, 13%) spike recovery. DTE had no effect on the immunoassay capture antibody but dramatically reduced the detection of recombinant eotaxin. Removal of DTE from sputum before immunoassay did not improve detection, although it restored the recovery of a subsequent eotaxin spike. In contrast, PBS-processed sputum resulted in an eotaxin spike recovery of 101% (SD, 20%). Addition of protease inhibitors or high-speed centrifugation had no effect on eotaxin detection. By using this optimized protocol, eotaxin levels in PBS-processed sputum samples were found to be significantly increased in asthmatic sputum (P<.05). CONCLUSION: Measurement of eotaxin by means of immunoassay is adversely affected by DTE, possibly through irreversible denaturation of epitopes, which makes eotaxin undetectable by using the immunoassay antibody. Sputum samples should be processed into PBS for assessment of eotaxin, which is present at increased levels in asthmatic sputum.

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

Ciclesonide ( Byk Gulden).

Ciclesonide, a non-halogenated inhaled corticosteroid with anti-inflammatory activity, is under development by Byk Gulden, Aventis and Teijin as a potential treatment for asthma [213439]. It was also being developed by Byk Gulden for chronic obstructive pulmonary disease (COPD), but no development had been reported for this indication since 1999; however, Teijin was carrying out clinical trials in this indication at the end of 2000. During 2000, Byk Gulden was carrying out phase III trials in the US and Europe and in March 2001, results were expected in the third quarter of 2001 [312399], [383726], [423659]. Two inhalant formulations (multidose powder and propellant filled) and a nasal formulation of ciclesonide are being developed by Byk Gulden for the treatment of asthma and seasonal allergic rhinitis, respectively [337147]. The compound is formulated for once-daily dosing and demonstrated good efficacy without corticosteroid-associated systemic side effects [409257]. In January 2001, Byk Gulden expected launch of a CFC-free multidose inhaler formulation in 2003 [395596]; in March 1999, launch of a nasal formulation was expected in 2004 and a multidose powder inhaler in 2005 [337147]. By September 2001, the compound was in phase III trials in the US for asthma, with a potential US launch anticipated by Aventis in 2004 [423465]. In November 2001, Aventis expected to submit an NDA to the FDA in 2003 [428057]. Teijin, which has a development and licensing agreement with Byk Gulden for the treatment of asthma and COPD in Japan, commenced phase I trials of ciclesonide in Japan in spring 1999, had completed these during 2000, and began phase II trials by September of that year [383726]. An NDA is expected to befiled in Japan in 2003. In October 2000 and April 2001, Merrill Lynch predicted peak sales of Euro400 million in 2007, with sales of Euro5 million in 2002, rising to Euro150 million in 2004 [395562], [420574]. Deutsche Bank predicted in August 2001, that sales of the product would reach Euro70 million in 2004, rising to Euro150 million in 2005 [420814].

Administration, Inhalation↗