31 results on '"Darryl A. Knight"'
Search Results
2. Dysregulated actin cytoskeleton associated with barrier dysfunction in asthma
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Christopher Grainge, Andrew T. Reid, Peter A. B. Wark, Nathan W. Bartlett, Kristy Nichol, Ngan Fung Li, and Darryl A. Knight
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business.industry ,Genetics ,medicine ,medicine.disease ,business ,Actin cytoskeleton ,Molecular Biology ,Biochemistry ,Biotechnology ,Cell biology ,Asthma - Published
- 2021
3. Mitochondrial dysfunction contributes to the senescent phenotype of IPF lung fibroblasts
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Cecilia M. Prêle, David W Waters, Michael Schuliga, Darryl A. Knight, Jade Jaffar, Cory M. Hogaboam, Christopher Grainge, Kaj E C Blokland, Nasreen Khalil, Jane Read, Steven E. Mutsaers, Dmitri V. Pechkovsky, Janette K. Burgess, Glen P. Westall, Andrew T. Reid, Groningen Research Institute for Asthma and COPD (GRIAC), and Restoring Organ Function by Means of Regenerative Medicine (REGENERATE)
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0301 basic medicine ,senescence ,antioxidant ,endogenous compound ,mTORC1 ,reactive oxygen metabolite ,Mitochondrion ,DNA damage response ,etoposide ,cyclin‐dependent kinase inhibitors ,rotenone ,cyclin-dependent kinase inhibitors ,stress ,chemistry.chemical_compound ,homeostasis ,peroxisome proliferator‐activated receptor gamma coactivator 1‐alpha ,mitochondrion ,Myofibroblasts ,Lung ,Cellular Senescence ,primary culture ,Superoxide ,adult ,article ,respiratory system ,idiopathic pulmonary fibrosis ,mechanistic target of rapamycin complex 1 ,enzyme activity ,Cell biology ,mitochondria ,medicine.anatomical_structure ,Molecular Medicine ,Original Article ,superoxide ,Signal transduction ,signal transduction ,Senescence ,phenotype ,DNA damage ,Down-Regulation ,cyclin dependent kinase inhibitor ,peroxisome proliferator-activated receptor gamma coactivator 1-alpha ,Cyclic N-Oxides ,03 medical and health sciences ,peroxisome proliferator activated receptor gamma coactivator 1alpha ,fibroblasts ,medicine ,Humans ,controlled study ,human ,Fibroblast ,Sirolimus ,reactive oxygen species and mitoTEMPO ,rapamycin ,human cell ,Original Articles ,mammalian target of rapamycin complex 1 ,Cell Biology ,Acetylcysteine ,respiratory tract diseases ,fibrosing alveolitis ,030104 developmental biology ,chemistry ,lung fibroblast ,Biomarkers ,Homeostasis - Abstract
Increasing evidence highlights that senescence plays an important role in idiopathic pulmonary fibrosis (IPF). This study delineates the specific contribution of mitochondria and the superoxide they form to the senescent phenotype of lung fibroblasts from IPF patients (IPF‐LFs). Primary cultures of IPF‐LFs exhibited an intensified DNA damage response (DDR) and were more senescent than age‐matched fibroblasts from control donors (Ctrl‐LFs). Furthermore, IPF‐LFs exhibited mitochondrial dysfunction, exemplified by increases in mitochondrial superoxide, DNA, stress and activation of mTORC1. The DNA damaging agent etoposide elicited a DDR and augmented senescence in Ctrl‐LFs, which were accompanied by disturbances in mitochondrial homoeostasis including heightened superoxide production. However, etoposide had no effect on IPF‐LFs. Mitochondrial perturbation by rotenone involving sharp increases in superoxide production also evoked a DDR and senescence in Ctrl‐LFs, but not IPF‐LFs. Inhibition of mTORC1, antioxidant treatment and a mitochondrial targeting antioxidant decelerated IPF‐LF senescence and/or attenuated pharmacologically induced Ctrl‐LF senescence. In conclusion, increased superoxide production by dysfunctional mitochondria reinforces lung fibroblast senescence via prolongation of the DDR. As part of an auto‐amplifying loop, mTORC1 is activated, altering mitochondrial homoeostasis and increasing superoxide production. Deeper understanding the mechanisms by which mitochondria contribute to fibroblast senescence in IPF has potentially important therapeutic implications.
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- 2018
4. Long‐chain fatty acids are bad in <scp>IPF</scp> , or are they?
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Darryl A. Knight and Bruce M. McManus
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Pulmonary and Respiratory Medicine ,medicine.medical_specialty ,Idiopathic pulmonary fibrosis ,business.industry ,Internal medicine ,Fatty Acids ,medicine ,Humans ,business ,medicine.disease ,Long chain ,Gastroenterology - Published
- 2020
5. Selective targeting of CREB-binding protein/β-catenin inhibits growth of and extracellular matrix remodelling by airway smooth muscle
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Mark H. Menzen, Tim Koopmans, Andrew J. Halayko, Tillie-Louise Hackett, Darryl A. Knight, Reinoud Gosens, and Stijn Crutzen
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0301 basic medicine ,Pharmacology ,Regulation of gene expression ,Beta-catenin ,biology ,Smooth muscle layer ,respiratory system ,Eosinophil ,Cell biology ,Extracellular matrix ,03 medical and health sciences ,Ovalbumin ,030104 developmental biology ,0302 clinical medicine ,medicine.anatomical_structure ,In vivo ,Catenin ,Immunology ,medicine ,biology.protein ,030217 neurology & neurosurgery - Abstract
Background and Purpose Asthma is a heterogeneous chronic inflammatory disease, characterized by the development of structural changes (airway remodelling). β-catenin, a transcriptional co-activator is fundamentally involved in airway smooth muscle growth, and may be a potential target in the treatment of airway smooth muscle remodelling. Experimental Approach Using small-molecule compounds that selectively target β-catenin breakdown or its interactions with transcriptional co-activators, we assessed their ability to inhibit airway smooth muscle remodelling in vitro and in vivo. Key Results ICG-001, a small-molecule compound that inhibits the β-catenin/CBP interaction, strongly and dose-dependently inhibited serum-induced smooth muscle growth and TGF-β1-induced production of extracellular matrix components in vitro. Inhibition of β-catenin/p300 interactions using IQ-1 or inhibition of tankyrase 1/2 using XAV-939 had considerably less effect. In a mouse model of allergic asthma, β-catenin expression in the smooth muscle layer was found unaltered in control versus ovalbumin-treated animals, a pattern that was found to be similar in smooth muscle within biopsies taken from asthmatic and non-asthmatic donors. However, β-catenin target gene expression was highly increased in response to ovalbumin, which was prevented by topical treatment with ICG-001. Interestingly, ICG-001 dose dependently reduced airway smooth thickness after repeated ovalbumin challenge, but had no effect on the deposition of collagen around the airways, mucus secretion or eosinophil infiltration. Conclusions and Implications Together, our findings highlight the importance of β-catenin/CBP signalling in the airways and suggest ICG-001 may be a new therapeutic approach to treat airway smooth muscle remodelling in asthma.
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- 2016
6. Transforming growth factor (TGF) β1 and Smad signalling pathways: A likely key to EMT-associated COPD pathogenesis
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Chris Ward, David W. Reid, Malik Quasir Mahmood, Darryl A. Knight, Sukhwinder Singh Sohal, HK Muller, and Eugene Haydn Walters
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0301 basic medicine ,Pulmonary and Respiratory Medicine ,Pathology ,medicine.medical_specialty ,Lamina propria ,COPD ,business.industry ,SMAD ,medicine.disease ,respiratory tract diseases ,Pathogenesis ,03 medical and health sciences ,030104 developmental biology ,0302 clinical medicine ,medicine.anatomical_structure ,030228 respiratory system ,Fibrosis ,medicine ,Epithelial–mesenchymal transition ,Lung cancer ,business ,Transforming growth factor - Abstract
Background and objective COPD is characterized by poorly reversible airflow obstruction usually due to cigarette smoking. Transforming growth factor (TGF)-β1 has been implicated in the pathogenesis of COPD, and in particular a process called epithelial mesenchymal transition (EMT), which may well be an intermediatory between smoking and both airway fibrosis and lung cancer. The downstream classical or ‘canonical’ TGF-β1 pathway is via the phosphorylated (p) Smad transcription factor system. Methods We have investigated TGF-β1 expression and its ‘pSmad fingerprint’ in bronchoscopic airway biopsies from patients with COPD, and in smoking and non-smoking controls. A cross-sectional immunohistochemical study compared TGF-β1 and pSmad 2, 3 (excitatory) and 7 (inhibitory) expression in cells and blood vessels of three compartments of large airways: epithelium (especially the basal region), reticular basement membrane (Rbm) and underlying lamina propria (LP). Results TGF-β1 expression was generally higher in COPD subjects throughout the airway wall (P
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- 2016
7. Impaired airway epithelial cell responses from children with asthma to rhinoviral infection
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Kak-Ming Ling, Alysia G. Buckley, Paul Rigby, Stephen M. Stick, Luke W. Garratt, Anthony Kicic, Francis J. Lannigan, Kevin Looi, Erika N. Sutanto, Thomas Iosifidis, Nicole C. Shaw, E. Kicic-Starcevich, Paul T. Stevens, K. Martinovich, and Darryl A. Knight
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Male ,0301 basic medicine ,Adolescent ,Rhinovirus ,Cell Survival ,medicine.medical_treatment ,Immunology ,Common Cold ,Apoptosis ,Respiratory Mucosa ,Biology ,Virus Replication ,Immunoglobulin E ,Virus ,03 medical and health sciences ,Immune system ,medicine ,Humans ,Immunology and Allergy ,Child ,Cell Proliferation ,Picornaviridae Infections ,Innate immune system ,Virus receptor ,Allergens ,Viral Load ,Asthma ,030104 developmental biology ,Cytokine ,Child, Preschool ,Disease Progression ,biology.protein ,Cytokines ,Receptors, Virus ,Respiratory epithelium ,Female ,Inflammation Mediators - Abstract
SummaryBackground The airway epithelium forms an effective immune and physical barrier that is essential for protecting the lung from potentially harmful inhaled stimuli including viruses. Human rhinovirus (HRV) infection is a known trigger of asthma exacerbations, although the mechanism by which this occurs is not fully understood. Objective To explore the relationship between apoptotic, innate immune and inflammatory responses to HRV infection in airway epithelial cells (AECs) obtained from children with asthma and non-asthmatic controls. In addition, to test the hypothesis that aberrant repair of epithelium from asthmatics is further dysregulated by HRV infection. Methods Airway epithelial brushings were obtained from 39 asthmatic and 36 non-asthmatic children. Primary cultures were established and exposed to HRV1b and HRV14. Virus receptor number, virus replication and progeny release were determined. Epithelial cell apoptosis, IFN-β production, inflammatory cytokine release and epithelial wound repair and proliferation were also measured. Results Virus proliferation and release was greater in airway epithelial cells from asthmatics but this was not related to the number of virus receptors. In epithelial cells from asthmatic children, virus infection dampened apoptosis, reduced IFN-β production and increased inflammatory cytokine production. HRV1b infection also inhibited wound repair capacity of epithelial cells isolated from non-asthmatic children and exaggerated the defective repair response seen in epithelial cells from asthmatics. Addition of IFN-β restored apoptosis, suppressed virus replication and improved repair of airway epithelial cells from asthmatics but did not reduce inflammatory cytokine production. Conclusions Collectively, HRV infection delays repair and inhibits apoptotic processes in epithelial cells from non-asthmatic and asthmatic children. The delayed repair is further exaggerated in cells from asthmatic children and is only partially reversed by exogenous IFN-β.
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- 2016
8. Reduced transforming growth factor β1 (TGF-β1) in the repair of airway epithelial cells of children with asthma
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E. Kicic-Starcevich, Luke W. Garratt, K. Martinovich, Thomas Iosifidis, Anthony Kicic, Erika N. Sutanto, Kevin Looi, Kak-Ming Ling, Darryl A. Knight, Stephen M. Stick, and Francis J. Lannigan
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0301 basic medicine ,Pulmonary and Respiratory Medicine ,Small interfering RNA ,Gene knockdown ,business.industry ,Lung injury ,03 medical and health sciences ,030104 developmental biology ,0302 clinical medicine ,Real-time polymerase chain reaction ,030228 respiratory system ,Immunology ,Gene expression ,cardiovascular system ,Medicine ,MMP14 ,Respiratory epithelium ,business ,Transforming growth factor - Abstract
Background and objective Evidence into the role of TGF-β1 in airway epithelial repair in asthma is still controversial. This study tested the hypothesis that the reduced TGF-β1 levels previously observed in paediatric asthmatic airway epithelial cells directly contribute to the dysregulated repair seen in these cells. Methods Primary airway epithelial cells (pAEC) from children with asthma (n = 16) and non-asthmatic subjects (n = 20) were isolated, and subcultured for investigation of TGF-β1 gene and protein via quantitative polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay (ELISA), respectively. Expression of other associated genes such as integrins αvβ6, αvβ8 and MT1-MMP were also tested. Small interfering RNA (siRNA) was employed to assess the role of TGF-β1 during wound repair. Results TGF-β1 gene and protein expression were significantly downregulated in asthmatic pAEC over the course of repair, compared with cells from non-asthmatic children. Messenger RNA (mRNA) expression of TGF-β1 was also directly implicated in non-asthmatic and asthmatic pAEC proliferation over their quiescent counterparts. Small interfering RNA-mediated knockdown of TGF-β1 compromised repair in non-asthmatic pAEC and exacerbated the dysregulated repair seen in asthmatic pAEC. Expression of major TGF-β1 activators of epithelial cells, integrin αvβ6 and αvβ8 was also measured and there was no difference in αvβ6 gene expression between the two cohorts. Although integrin αvβ8 gene expression was significantly higher in asthmatic pAEC, the expression of MT1-MMP (MMP14) which facilitates the αvβ8 mediated TGF-β1 activation was significantly downregulated. Conclusion Our data has highlighted the importance of TGF-β1 in pAEC wound repair in vitro. The significantly lower levels seen in asthmatic pAEC subsequently contributes to the dysregulated repair observed in these cells.
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- 2016
9. TSANZ Ann Woolcock Young Investigator Awards Oral Presentations
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David W Waters, Ian M. Adcock, Malcolm R. Starkey, N Smithers, Andrew G. Jarnicki, Kamal Dua, Bernadette Jones, Philip M. Hansbro, Darryl A. Knight, Celeste L. Harrison, and Peter A. B. Wark
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Pulmonary and Respiratory Medicine ,business.industry ,Immunology ,Medicine ,Pulmonary disease ,Disease ,Respiratory system ,business ,Bromodomain - Published
- 2016
10. Airway epithelial repair in health and disease: Orchestrator or simply a player?
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Luke W. Garratt, Anthony Kicic, Darryl A. Knight, Thomas Iosifidis, Stephen M. Stick, and Deirdre R. Coombe
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0301 basic medicine ,Pulmonary and Respiratory Medicine ,business.industry ,First line ,Context (language use) ,Disease ,Epithelial cell migration ,Epithelium ,03 medical and health sciences ,030104 developmental biology ,0302 clinical medicine ,medicine.anatomical_structure ,030228 respiratory system ,Immunology ,medicine ,Respiratory epithelium ,business ,Airway ,Neuroscience ,Homeostasis - Abstract
Epithelial cells represent the most important surface of contact in the body and form the first line of defence of the body to external environment. Consequently, epithelia have numerous roles in order to maintain a homeostatic defence barrier. Although the epithelium has been extensively studied over several decades, it remains the focus of new research, indicating a lack of understanding that continues to exist around these cells in specific disease settings. Importantly, evidence is emerging that airway epithelial cells in particular have varied complex functions rather than simple passive roles. One area of current interest is its role following injury. In particular, the epithelial-specific cellular mechanisms regulating their migration during wound repair remain poorly understood and remain an area that requires much needed investigation. A better understanding of the physiological, cellular and molecular wound repair mechanisms could assist in elucidating pathological processes that contribute to airway epithelial pathology. This review attempts to highlight migration-specific and cell-extracellular matrix (ECM) aspects of repair used by epithelial cells under normal and disease settings, in the context of human airways.
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- 2016
11. Hypoxia Inducible Factor (HIF)‐1 accelerates mucosal wound healing through regulation and trafficking of integrin‐α5β1
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Jay C. Horvat, Simonne Sherwin, Bridie J. Goggins, Marjorie M. Walker, Simon Keely, Darryl A. Knight, Gang Liu, and Kyra Minahan
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Integrin α5β1 ,Hypoxia-inducible factors ,business.industry ,Genetics ,Medicine ,business ,Wound healing ,Molecular Biology ,Biochemistry ,Biotechnology ,Cell biology - Published
- 2020
12. Hypoxia Inducible Factor (HIF)‐1 Accelerates Epithelial Wound Healing Through Regulation of Integrin‐α5β1
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Jay C. Horvat, Marjorie M. Walker, Andrea Mathe, Darryl A. Knight, Bridie J. Goggins, Simon Keely, Gang Liu, and Kyra Minahan
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Integrin α5β1 ,Hypoxia-inducible factors ,Chemistry ,Genetics ,Wound healing ,Molecular Biology ,Biochemistry ,Biotechnology ,Cell biology - Published
- 2018
13. International research collaboration: The way forward
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Sanjay H. Chotirmall, Kian Fan Chung, Fred W. S. Wong, Christopher Carlsten, Sven-Erik Dahlén, Reinoud Gosens, and Darryl A. Knight
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Pulmonary and Respiratory Medicine ,International research ,03 medical and health sciences ,Medical education ,0302 clinical medicine ,030228 respiratory system ,business.industry ,MEDLINE ,Medicine ,030212 general & internal medicine ,business - Published
- 2018
14. Year in review 2011: Asthma, chronic obstructive pulmonary disease and airway biology
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Ian A. Yang, Darryl A. Knight, Fanny W.S. Ko, and T. K. Lim
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Pulmonary and Respiratory Medicine ,Asthma therapy ,medicine.medical_specialty ,business.industry ,Year in review ,MEDLINE ,Pulmonary disease ,University hospital ,Asthma chronic ,Research centre ,Lung health ,Family medicine ,Medicine ,business ,human activities - Abstract
1UBC James Hogg Research Centre, Institute for Heart + Lung Health, Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Vancouver, Canada, 2The Prince Charles Hospital and The University of Queensland, Brisbane, Queensland, Australia, 3Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, and 4Department of Medicine, National University Hospital, Singapore, Singapore
- Published
- 2012
15. Year-in-review 2010: Asthma, COPD, cystic fibrosis and airway biology
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Darryl A. Knight, T. K. Lim, Helen K. Reddel, Claire E. Wainwright, and Michiaki Mishima
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Pulmonary and Respiratory Medicine ,medicine.medical_specialty ,business.industry ,Year in review ,medicine ,Asthma copd ,Intensive care medicine ,business ,medicine.disease ,Airway ,Cystic fibrosis ,Asthma - Published
- 2011
16. A versatile approach for the syntheses of poly(ester amide)s with pendant functional groups
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Kibret Mequanint, Darryl K. Knight, Katelyn M. Atkins, David Lopez, and Elizabeth R. Gillies
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Terephthalic acid ,chemistry.chemical_classification ,Polymers and Plastics ,Carboxylic acid ,Organic Chemistry ,Nuclear magnetic resonance spectroscopy ,Amino acid ,chemistry.chemical_compound ,Hydrolysis ,Monomer ,chemistry ,Amide ,Materials Chemistry ,Side chain ,Organic chemistry - Abstract
Poly(ester amide)s (PEAs) are emerging as promising materials for a wide range of biomedical applications due to their potential for both hydrolytic and enzymatic degradation, as well as the ease with which their properties can be tuned by the choice of monomers. The incorporation of pendant functional handles along the PEA backbone has the potential to further expand their applications by allowing the charge and hydrophilicity of the polymers to be altered, and facilitating the conjugation of active molecules such as drugs, targeting groups, and cell signaling molecules. Described here is a simple and versatile strategy based on orthogonal protecting groups, by which L -lysine and L -aspartic acid can be incorporated into several families of PEAs based on monomers including the diacids succinic and terephthalic acid, the diols 1,4-butanediol and 1,8-octanediol, and the amino acids L -alanine and L -phenylalanine. All polymers were thoroughly characterized by nuclear magnetic resonance spectroscopy, infrared spectroscopy, size exclusion chromatography, thermogravimetric analysis, and differential scanning calorimetry. It was demonstrated that the side chain protecting groups could be readily removed, allowing the pendant amines or carboxylic acids to be functionalized. In particular, the carboxylic acid groups on a polymer containing L -aspartic acid units were converted to N-hydroxy-succinimidyl esters, providing a useful template for further derivatization.
- Published
- 2009
17. Dysregulated repair in asthmatic paediatric airway epithelial cells: the role of plasminogen activator inhibitor-1
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Darryl A. Knight, Anthony Kicic, Stephen M. Stick, Erika N. Sutanto, and Paul T. Stevens
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Male ,Immunology ,Cell ,Bronchi ,Respiratory Mucosa ,Epithelial Damage ,Extracellular matrix ,chemistry.chemical_compound ,Plasminogen Activator Inhibitor 1 ,medicine ,Humans ,Immunology and Allergy ,Gene silencing ,Gene Silencing ,Child ,Cells, Cultured ,Wound Healing ,business.industry ,Asthma ,Epithelium ,medicine.anatomical_structure ,chemistry ,Child, Preschool ,Plasminogen activator inhibitor-1 ,Female ,business ,Wound healing ,Plasminogen activator - Abstract
Summary Background Asthma is associated with structural changes to airways such as extracellular matrix deposition and epithelial damage. Evidence suggests that asthmatic airway epithelial repair is abnormal and that elevated plasminogen activator inhibitor-1 levels observed in asthma may be involved in the epithelial repair process and in excessive matrix accumulation. Objective To assess the ability of asthmatic airway epithelial cells (AECs) to repair mechanically induced wounds and to investigate the role that plasminogen activator inhibitor-1 plays in the repair process. Methods AECs were isolated from atopic asthmatic and healthy non-atopic children by bronchial brushing, subcultured and wound repair experiments were performed. Plasminogen activator inhibitor-1 gene expression was assessed using real-time PCR while protein activity was measured in cell lysates as well as plasma. The role of plasminogen activator inhibitor-1 in epithelial proliferation and wound repair was investigated using siRNA. Results Cells from asthmatic children have a significantly longer repair time in comparison with cells from otherwise healthy donors. Plasminogen activator inhibitor-1 mRNA expression was up-regulated 68-fold in freshly isolated asthmatic cells compared with normal cells, and protein levels were also significantly elevated in the asthmatic cell lysates, but plasma levels were similar in both groups. Plasminogen activator inhibitor-1 cells expression increased in both cohorts during culture. Gene silencing substantially reduced the rate of proliferation in asthmatic and healthy cells. Mechanical wounding of epithelial monolayers induced plasminogen activator inhibitor-1 expression in asthmatic and non-asthmatic cohorts, while gene silencing delayed wound repair of healthy cell, with minimal effect on those from asthmatics. Conclusion Asthmatic AECs are inherently dysfunctional in their ability to repair wounds; plasminogen activator inhibitor-1 mRNA and protein activity are constitutively up-regulated in asthmatic epithelium and play functional roles in both proliferation and repair of healthy cells. In asthmatic cells, elevated plasminogen activator inhibitors-1 levels fail to stimulate epithelial repair.
- Published
- 2008
18. Structure, depolymerization, and cytocompatibility evaluation of glycol chitosan
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Brian G. Amsden, Stephen N. Shapka, and Darryl K. Knight
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Nitrosamines ,Materials science ,Tertiary amine ,Potassium Compounds ,Chemical structure ,Biomedical Engineering ,Biocompatible Materials ,Nitrous Acid ,Cell Line ,Biomaterials ,chemistry.chemical_compound ,Chondrocytes ,Materials Testing ,Animals ,Organic chemistry ,Cell Proliferation ,chemistry.chemical_classification ,Chitosan ,Nitrous acid ,Sulfates ,Depolymerization ,technology, industry, and agriculture ,Metals and Alloys ,Polymer ,Potassium persulfate ,Hydrogen-Ion Concentration ,chemistry ,Carcinogens ,Ceramics and Composites ,Molar mass distribution ,Amine gas treating - Abstract
Glycol chitosan, a water soluble chitosan derivative being investigated as a new biomaterial, was fractionated via two different methods. Initial characterization of the glycol chitosan with (1)H NMR spectroscopy illustrated the presence of both secondary and tertiary amine groups, contradictory to its widely accepted structure. Fractionation of glycol chitosan with nitrous acid resulted in a significant reduction in the number average molecular weight, specifically, from 170 to approximately 7 kDa for a pH 3 and below. However, the reaction altered its chemical structure, as the secondary amine groups were converted to N-nitrosamines, which are potentially carcinogenic. An increase in the pH of the reaction limited this formation, but not entirely. Free radical degradation initiated with potassium persulfate was not as effective at reducing the molecular weight as the nitrous acid approach, yielding molecular weights around 12 kDa under the same molar ratio of degrading species, but did retain the structural integrity of the glycol chitosan. Additionally, control of the molecular weight appears feasible with potassium persulfate. When assessed in vitro for cytocompatibility, the polymer exhibited no toxicity on monolayer-cultured chondrocytes, and in fact stimulated cell growth at low concentrations.
- Published
- 2007
19. Comparison of the morphological and biochemical changes in normal human lung fibroblasts and fibroblasts derived from lungs of patients with idiopathic pulmonary fibrosis during FasL-induced apoptosis
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Philip J. Thompson, Amelia K. Scaffidi, Robin J. McAnulty, John M. Papadimitriou, Yuben Moodley, Darryl A. Knight, Paul Caterina, Geoffrey J. Laurent, and Neil L. A. Misso
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Programmed cell death ,Pathology ,medicine.medical_specialty ,Fas Ligand Protein ,Pulmonary Fibrosis ,Apoptosis ,DNA Fragmentation ,Biology ,Fas ligand ,Pathology and Forensic Medicine ,chemistry.chemical_compound ,Idiopathic pulmonary fibrosis ,Fibrosis ,Pulmonary fibrosis ,medicine ,Humans ,Fibroblast ,Lung ,Cells, Cultured ,Membrane Glycoproteins ,Microscopy, Video ,Caspase 3 ,Cell Membrane ,Phosphatidylserine ,Fibroblasts ,medicine.disease ,Microscopy, Electron ,medicine.anatomical_structure ,chemistry ,Caspases ,Vacuoles ,Cancer research - Abstract
It is increasingly recognized that the morphological changes of apoptosis vary between cell types. This heterogeneity reflects the wide range of cellular proteins and enzymes involved in apoptotic pathways. Fibroblast apoptosis is crucial to the regression of scars and the restitution of healthy tissue during wound repair and may be aberrant in diseases such as idiopathic pulmonary fibrosis (IPF). The biochemical and morphological changes characterizing fibroblast apoptosis are unknown and may provide insights into the specific enzymatic mediators activated in these cells. This study aimed to examine the morphological changes of fibroblast apoptosis in both primary normal lung fibroblasts (normal-Fb) and fibroblasts obtained from patients with idiopathic pulmonary fibrosis (IPF-Fb) and to correlate these changes with conventional biochemical markers. Transmission electron microscopy (TEM) and video time-lapse microscopy demonstrated no difference in the duration of fibroblast apoptosis in response to FasL (6 +/- 0.3 h in normal-Fb and 6.4 +/- 0.2 h in IPF-Fb). However, IPF-Fb were more resistant to FasL-induced apoptosis compared with normal-Fb. Although the majority of morphological changes of normal-Fb and IPF-Fb were similar, the formation of filopodia and condensation of the cytoskeletal bundles in IPF-Fb, and more prominent vacuolation in normal-Fb, were the significant differences between these cell subtypes. Loss of the mitochondrial membrane potential occurred prior to caspase-3 activation, while phosphatidylserine expression, cytokeratin-18 cleavage, and DNA fragmentation commenced after caspase-3 activation. These observations not only suggest that specific enzymatic effectors may be preferentially activated during fibroblast apoptosis, but also provide potential insights into the pathogenesis of IPF.
- Published
- 2004
20. The airway epithelium: Structural and functional properties in health and disease
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Stephen T. Holgate and Darryl A. Knight
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Pulmonary and Respiratory Medicine ,business.industry ,Mesenchyme ,Respiratory disease ,Inflammation ,Respiratory Mucosa ,Disease ,medicine.disease ,Neurosecretory Systems ,Asthma ,Basement Membrane ,Epithelium ,medicine.anatomical_structure ,Immune system ,Immunology ,medicine ,Humans ,Respiratory epithelium ,medicine.symptom ,Growth Substances ,business ,Airway ,Glucocorticoids - Abstract
The major function of the respiratory epithelium was once thought to be that of a physical barrier. However, it constitutes the interface between the internal milieu and the external environment as well as being a primary target for inhaled respiratory drugs. It also responds to changes in the external environment by secreting a large number of molecules and mediators that signal to cells of the immune system and underlying mesenchyme. Thus, the epithelium is in a unique position to translate gene-environment interactions. Normally, the epithelium has a tremendous capacity to repair itself following injury. However, evidence is rapidly accumulating to show that the airway epithelium of asthmatics is abnormal and has increased susceptibility to injury compared to normal epithelium. Areas of detachment and fragility are a characteristic feature not observed in other inflammatory diseases such as COPD. In addition to being more susceptible to damage, normal repair processes are also compromised. Failure of appropriate growth and differentiation of airway epithelial cells will cause persistent mucosal injury. The response to traditional therapy such as glucocorticoids may also be compromised. However, whether the differences observed in asthmatic epithelium are a cause of or secondary to the development of the disease remains unanswered. Strategies to address this question include careful examination of the ontogeny of the disease in children and use of gene array technology should provide some important answers, as well as allow a better understanding of the critical role that the epithelium plays under normal conditions and in diseases such as asthma.
- Published
- 2003
21. Oncostatin M: an interleukin-6-like cytokine relevant to airway remodelling and the pathogenesis of asthma
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Kirrily O'Hara, Phillip J Thompson, Mary-Anne Kedda, and Darryl A. Knight
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Allergy ,biology ,business.industry ,medicine.medical_treatment ,Immunology ,Respiratory disease ,Oncostatin M ,medicine.disease ,Pathogenesis ,medicine.anatomical_structure ,Cytokine ,medicine ,biology.protein ,Immunology and Allergy ,business ,Interleukin 6 ,Respiratory tract ,Asthma - Published
- 2003
22. Oncostatin M stimulates proliferation, induces collagen production and inhibits apoptosis of human lung fibroblasts
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Steven E. Mutsaers, Philip J. Thompson, Geoffrey J. Laurent, Darryl A. Knight, Amelia K. Scaffidi, Robin J. McAnulty, and Yuben Moodley
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Pharmacology ,MAPK/ERK pathway ,medicine.medical_specialty ,Kinase ,medicine.medical_treatment ,fungi ,Oncostatin M ,Biology ,Molecular biology ,medicine.anatomical_structure ,Cytokine ,Endocrinology ,Apoptosis ,Annexin ,Internal medicine ,Mitogen-activated protein kinase ,medicine ,biology.protein ,Fibroblast - Abstract
Oncostatin M (OSM), a member of the interleukin-6 (IL-6) cytokine family, acts on a variety of cells and elicits diversified biological responses, suggesting potential roles in the regulation of cell survival, differentiation and proliferation. We have examined the effect of OSM on the regulation of human lung fibroblast proliferation, collagen production and spontaneous apoptosis. The proliferative effects of OSM (0.5 – 100 ng ml−1) were assessed using a MTS assay as well as [3H]-thymidine incorporation and cell counts at 24 and 48 h. Hydroxyproline was measured as an index of procollagen production by high pressure liquid chromotography (HPLC). Apoptosis was determined by annexin staining. OSM enhanced the mitotic activity of lung fibroblasts in a time and dose dependent manner. Maximum proliferation of 57% above control was observed after incubation for 48 h with 2 ng ml−1 OSM (P
- Published
- 2002
23. Protease-activated receptors and the airway epithelium
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Darryl A. Knight, Philip J. Thompson, Geoffrey A. Stewart, and Nithiananthan Asokananthan
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Pathology ,medicine.medical_specialty ,Protease ,business.industry ,medicine.medical_treatment ,Immunology ,medicine ,Immunology and Allergy ,Respiratory epithelium ,business ,Receptor - Published
- 2001
24. Role of PGE2in protease-activated receptor-1, −2 and −4 mediated relaxation in the mouse isolated trachea
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Darryl A. Knight, Peter J. Henry, Rommel S. Lan, and Geoff A Stewart
- Subjects
Pharmacology ,medicine.medical_specialty ,biology ,Chemistry ,medicine.drug_class ,Prostanoid ,Receptor antagonist ,chemistry.chemical_compound ,Muscle relaxation ,Endocrinology ,Protease-Activated Receptor 1 ,Mechanism of action ,Enzyme inhibitor ,Internal medicine ,medicine ,biology.protein ,medicine.symptom ,Prostaglandin E2 ,Receptor ,medicine.drug - Abstract
1. The potential mediator role of the prostanoid PGE(2) in airway smooth muscle relaxations induced by peptidic and proteolytic activators of PAR-1, PAR-2, PAR-3 and PAR-4 was investigated in carbachol-precontracted mouse isolated tracheal segments. 2. The tethered ligand domain sequences of murine PAR-1 (SFFLRN-NH(2)), PAR-2 (SLIGRL-NH(2)) and PAR-4 (GYPGKF-NH(2)), but not PAR-3 (SFNGGP-NH(2)), induced smooth muscle relaxation that was abolished by the non-selective cyclo-oxygenase (COX) inhibitor, indomethacin. The relative order for mean peak relaxation was SLIGRL-NH(2)>GYPGKF-NH(2) approximately amp; SFFLRN-NH(2)>SFNGGP-NH(2). 3. SFFLRN-NH(2), SLIGRL-NH(2) and GYPGKF-NH(2), but not SFNGGP-NH(2), induced significant PGE(2) release that was abolished by indomethacin. Like that for relaxation, the relative order for mean PGE(2) release was SLIGRL-NH(2)>GYPGKF-NH(2)>SFFLRN-NH(2)>SFNGGP-NH(2). 4. In dose-response studies, SLIGRL-NH(2) induced concentration-dependent increases in PGE(2) release (EC(50)=20.4 microM) and smooth muscle relaxation (EC(50)=15.8 microM). 5. The selective COX-2 inhibitor, nimesulide, but not the COX-1 inhibitor valeryl salicylate, significantly attenuated SLIGRL-NH(2)-induced smooth muscle relaxation and PGE(2) release. 6. Exogenously applied PGE(2) induced potent smooth muscle relaxation (EC(50)=60.3 nM) that was inhibited by the mixed DP/EP(1)/EP(2) prostanoid receptor antagonist, AH6809. SLIGRL-NH(2)-induced relaxation was also significantly inhibited by AH6809. 7. In summary, the results of this study strongly suggest that PAR-mediated relaxation in murine tracheal smooth muscle is dependent on the generation of the spasmolytic prostanoid, PGE(2). PAR-stimulated PGE(2) release appears to be generated preferentially by COX-2 rather than COX-1, and induces relaxation via activation of the EP(2) receptor.
- Published
- 2001
25. Oncostatin M synergises with house dust mite proteases to induce the production of PGE2from cultured lung epithelial cells
- Author
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Neil L. A. Misso, Philip J. Thompson, D. Neil Watkins, Nithiananthan Asokananthan, Geoffrey A. Stewart, and Darryl A. Knight
- Subjects
medicine.medical_specialty ,Proteases ,Leukemia Inhibitory Factor Receptor alpha Subunit ,Receptors, OSM-LIF ,medicine.medical_treatment ,Oncostatin M ,Biology ,Nitric Oxide ,Leukemia Inhibitory Factor ,Dinoprostone ,Internal medicine ,Endopeptidases ,Lolium ,medicine ,Animals ,Humans ,Receptors, Cytokine ,Interleukin 6 ,Lung ,Cells, Cultured ,Pharmacology ,Lymphokines ,Mites ,Interleukin-6 ,Plant Extracts ,fungi ,Lymphokine ,Drug Synergism ,Epithelial Cells ,Receptors, Oncostatin M ,Immunohistochemistry ,Molecular biology ,Growth Inhibitors ,Cytokine ,Endocrinology ,Cell culture ,Papers ,biology.protein ,Cytokines ,Pollen ,Respiratory epithelium ,Peptides ,Leukemia inhibitory factor - Abstract
The release of PGE(2) and nitric oxide (NO) from the respiratory epithelium may act to dampen inflammation. In other tissues, oncostatin M (OSM), a potent inducer of epithelial antiproteases, has also been shown to interact with IL-1beta to stimulate PGE(2) release. However, whether OSM interacts with pro-inflammatory cytokines and proteases in the production of anti-inflammatory eicosanoids and NO from airway epithelium is unknown. The effect of OSM and the related cytokine leukaemia inhibitory factor (LIF) on PGE(2) and NO production by the respiratory epithelial cell line, A549 in response to pro-inflammatory cytokines as well as protease-rich house dust mite (HDM) fractions and a protease-deficient rye grass pollen extract was examined by immunohistochemistry, cell culture, ELISA and enzyme-immunoassay. Cells treated with a mixture of IL-1beta, IFNgamma and LPS for 48 h produced a 9 fold increase in PGE(2) and a 3 fold increase in NO levels (both P
- Published
- 2000
26. Leukaemia inhibitory factor (LIF) upregulates excitatory non-adrenergic non-cholinergic and maintains cholinergic neural function in tracheal explants
- Author
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Angela C. D'Aprile, Philip J. Thompson, Roy G. Goldie, L.J. Spalding, and Darryl A. Knight
- Subjects
endocrine system ,medicine.medical_specialty ,Carbachol ,Receptors, OSM-LIF ,Neutrophils ,Guinea Pigs ,Cmax ,Substance P ,Biology ,Leukemia Inhibitory Factor ,chemistry.chemical_compound ,Internal medicine ,Muscarinic acetylcholine receptor ,medicine ,Animals ,Receptors, Cytokine ,Special Report ,reproductive and urinary physiology ,Pharmacology ,Lymphokines ,Receptor, Muscarinic M2 ,urogenital system ,Interleukin-6 ,Muscarinic acetylcholine receptor M2 ,Receptors, Muscarinic ,Growth Inhibitors ,Trachea ,medicine.anatomical_structure ,Endocrinology ,chemistry ,embryonic structures ,Cholinergic ,Leukemia inhibitory factor ,hormones, hormone substitutes, and hormone antagonists ,Muscle Contraction ,Sensory nerve ,medicine.drug - Abstract
The effect of leukaemia inhibitory factor (LIF) in modulating cholinergic and sensory nerve function was examined using guinea-pig tracheal explants. Specific LIF receptors (LIFR) were immunolocalized to both cholinergic and sensory nerves. Release of SP in culture was not influenced by LIF. Similarly, maximum contraction to carbachol (Cmax) was not influenced by LIF. After 3 h, maximum (Emax) eNANC-induced contraction in controls was 32±2.5% of Cmax. In LIF-treated preparations, Emax was enhanced to 50±4.5% Cmax (P
- Published
- 2000
27. Localization of leukaemia inhibitory factor to airway epithelium and its amplification of contractile responses to tachykinins
- Author
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Barry Wiggs, Tony R. Bai, R. Robert Schellenberg, Darryl A. Knight, and Karen McKay
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Pharmacology ,Agonist ,medicine.medical_specialty ,Carbachol ,medicine.drug_class ,respiratory system ,Biology ,chemistry.chemical_compound ,Endocrinology ,chemistry ,Capsaicin ,Internal medicine ,Isoprenaline ,medicine ,Respiratory epithelium ,Neurokinin A ,Receptor ,Leukemia inhibitory factor ,medicine.drug - Abstract
In neural tissue, leukaemia inhibitory factor (LIF) is an important trophic cytokine. In this investigation, we determined if LIF was present in human and guinea-pig airways and examined the role of this cytokine in modulating airway responses to endogenous and exogenous tachykinins as well as muscarinic receptor and β-adrenoceptor stimulation. The presence of LIF in both human and guinea-pig airways was determined by immunohistochemistry. Guinea-pig tracheal explants were incubated in CRML-1066 media containing LIF (0.5, 5 or 50 ng ml−1) for periods of 3, 6, 24 and 48 h. Tracheal rings were then transferred to organ baths for measurement of isometric force in response to carbachol, capsaicin, the neurokinin1 (NK1) receptor agonist [Sar9,Met(O2)11]-substance P (SP), the NK2 receptor agonist neurokinin A (NKA) and isoprenaline. LIF immunoreactivity was observed primarily in basally situated cells in the airway epithelium of both large and small airways. Less intense immunoreactivity was observed in vascular endothelium and glandular epithelium. Treatment with LIF (0.5 ng ml−1) for 3 and 6 h significantly increased contractile responses to capsaicin by 42% and 43%, respectively, compared to time controls, whereas higher concentrations of LIF (5 and 50 ng ml−1) enhanced capsaicin-induced contractions only after 6 h. After 24 h, responses to capsaicin were not significantly different from 0 h control. Contractile responses to capsaicin following exposure to LIF at any concentration for 24 h were not significantly different from relative time control values. Responses to [Sar9,Met(O2)11]-SP, carbachol and isoprenaline were not influenced by time in culture or by exposure to LIF for up to 48 h. Contractile responses induced by NKA were not influenced by 3 or 6 h exposure to LIF, but at 24 and 48 h the mean maximum contractile responses to NKA were significantly increased by 33% and 35%, respectively, compared to control. These results demonstrate that LIF is present in guinea-pig and human airway epithelium, and modulates airway responses to tachykinins. In the acute setting LIF augments the capsaicin-induced release of endogenous tachykinins, whilst in the longer term (>24 h), LIF increases airway smooth muscle responses to tachykinins via an NK2 receptor selective mechanism. We conclude that LIF may be an important effector molecule in the response of airways to injury or inflammation. British Journal of Pharmacology (1997) 120, 883–891; doi:10.1038/sj.bjp.0700965
- Published
- 1997
28. Elucidating novel disease mechanisms in severe asthma
- Author
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Rachel Neal, Malcolm R. Starkey, Philip M. Hansbro, Richard Kim, Lohis Balachandran, Chantal Donovan, Darryl A. Knight, Brittany Rae, James W. Pinkerton, and Jay C. Horvat
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0301 basic medicine ,business.industry ,Severe asthma ,Immunology ,Disease mechanisms ,food and beverages ,Pulmonary disease ,Inflammatory Bowel Diseases ,Review ,medicine.disease ,Omics ,03 medical and health sciences ,030104 developmental biology ,0302 clinical medicine ,030228 respiratory system ,Rheumatoid arthritis ,medicine ,Immunology and Allergy ,business ,Nephrotic syndrome ,General Nursing ,Asthma - Abstract
Corticosteroids are broadly active and potent anti-inflammatory agents that, despite the introduction of biologics, remain as the mainstay therapy for many chronic inflammatory diseases, including inflammatory bowel diseases, nephrotic syndrome, rheumatoid arthritis, chronic obstructive pulmonary disease and asthma. Significantly, there are cohorts of these patients with poor sensitivity to steroid treatment even with high doses, which can lead to many iatrogenic side effects. The dose-limiting toxicity of corticosteroids, and the lack of effective therapeutic alternatives, leads to substantial excess morbidity and healthcare expenditure. We have developed novel murine models of respiratory infection-induced, severe, steroid-resistant asthma that recapitulate the hallmark features of the human disease. These models can be used to elucidate novel disease mechanisms and identify new therapeutic targets in severe asthma. Hypothesis-driven studies can elucidate the roles of specific factors and pathways. Alternatively, 'Omics approaches can be used to rapidly generate new targets. Similar approaches can be used in other diseases.
- Published
- 2016
29. The respiratory epithelium and airway smooth muscle homeostasis: its relevance to asthma
- Author
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Philip J. Thompson, Glen A. Stewart, and Darryl A. Knight
- Subjects
Pathology ,medicine.medical_specialty ,business.industry ,Respiratory System ,Immunology ,Respiratory disease ,Muscle, Smooth ,Airway smooth muscle ,medicine.disease ,Asthma ,Epithelium ,Pathophysiology ,Smooth muscle ,Respiratory Physiological Phenomena ,medicine ,Homeostasis ,Humans ,Immunology and Allergy ,Respiratory epithelium ,business - Published
- 1994
30. Increased permeability of asthmatic epithelial cells to pollutants. Does this mean that they are intrinsically abnormal?
- Author
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Darryl A. Knight
- Subjects
Pollutant ,Permeability (electromagnetism) ,Chemistry ,Immunology ,Biophysics ,Immunology and Allergy - Published
- 2002
31. The contribution of animal models to understanding the role of the immune system in human idiopathic pulmonary fibrosis
- Author
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Tylah Miles, Gerard F Hoyne, Darryl A Knight, Mark W Fear, Steven E Mutsaers, and Cecilia M Prêle
- Subjects
animal models ,bleomycin ,fibrogenesis ,inflammation ,innate and adaptive immune system ,Immunologic diseases. Allergy ,RC581-607 - Abstract
Abstract Pulmonary fibrosis occurs in a heterogeneous group of lung disorders and is characterised by an excessive deposition of extracellular matrix proteins within the pulmonary interstitium, leading to impaired gas transfer and a loss of lung function. In the past 10 years, there has been a dramatic increase in our understanding of the immune system and how it contributes to fibrogenic processes within the lung. This review will compare some of the models used to investigate the pathogenesis and treatment of pulmonary fibrosis, in particular those used to study immune cell pathogenicity in idiopathic pulmonary fibrosis, highlighting their advantages and disadvantages in dissecting human disease.
- Published
- 2020
- Full Text
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