The breathing difficulty experienced by asthmatics occurs because of excessive narrowing in the bronchial tubes or airways. These airways are normally held open by the pressures in the chest during breathing. It is possible that the excessive airway narrowing in asthma occurs because these pressures are no longer effective. This may be due to changes in the airway stiffness which occurs during asthma. The project will involve experts Canada and Australia who have developed new techniques which a ....The breathing difficulty experienced by asthmatics occurs because of excessive narrowing in the bronchial tubes or airways. These airways are normally held open by the pressures in the chest during breathing. It is possible that the excessive airway narrowing in asthma occurs because these pressures are no longer effective. This may be due to changes in the airway stiffness which occurs during asthma. The project will involve experts Canada and Australia who have developed new techniques which allow the airways to be seen so that these changes can be measured.Read moreRead less
ORIGIN AND REGULATION OF VAGAL PREGANGLIONIC NEURON SUBTYPES CONTROLLING AIRWAY SMOOTH MUSCLE TONE
Funder
National Health and Medical Research Council
Funding Amount
$438,700.00
Summary
The primary role of the airways is to allow the exchange of oxygen and carbon dioxide between the environment and the lungs. However, the airways are not merely a series of static tubes, but rather their size (or caliber) is subject to breath-by-breath alterations, thereby regulating gas exchange to match the body's demands. Regulation of airway caliber is achieved largely by subconscious changes in the tone of the muscle lining the airway wall. Airway muscle tone is primarily under the control ....The primary role of the airways is to allow the exchange of oxygen and carbon dioxide between the environment and the lungs. However, the airways are not merely a series of static tubes, but rather their size (or caliber) is subject to breath-by-breath alterations, thereby regulating gas exchange to match the body's demands. Regulation of airway caliber is achieved largely by subconscious changes in the tone of the muscle lining the airway wall. Airway muscle tone is primarily under the control of the parasympathetic division of the autonomic nervous system. Two distinct types of parasympathetic nerves innervate the airways: One type employs the neurotransmitter acetylcholine which causes airway muscle to contract and the airways to constrict, while the other type employs nitric oxide which evokes airway dilatation. The normal regulation of airway caliber is altered in a variety of inflammatory airways diseases. In asthma and chronic obstructive pulmonary disease (COPD) there is an increase in airway muscle tone (airway constriction) which compromises the normal movement of gasses and contributes to the morbidity and mortality of the diseases. There is a growing body of evidence to suggest that exaggerated airway muscle tone may in part result from dysfunction of either the contractile or relaxant parasympathetic nerves innervating the airways. However, at present very little is known about the parasympathetic pathways regulating airway caliber. A complete understanding of the mechanisms controlling airway smooth muscle tone is therefore essential to fully understanding possible role of autonomic dysfunction in the pathogenesis of obstructive airways diseases. The aim of this grant is to better define the physiological and anatomical properties of airway parasympathetic nerves in the brain stem.Read moreRead less
Functional Analysis Of The Ym2 Chitinase-like Lectin In Allergic Airways Disease
Funder
National Health and Medical Research Council
Funding Amount
$283,767.00
Summary
The prevalence of asthma is widespread and nationally affects over two million Australians. Consequently, one of the Country s National Health Priorities is to improve our understanding of this condition. Analyses of the asthmatic lung reveal an airway wall that is thickened, an airway lumen that is obstructed and abnormal spasmogenicity of the airway smooth muscle: processes that collectively contribute to both acute and chronic respiratory dysfunction. Asthmatics develop an immune response tha ....The prevalence of asthma is widespread and nationally affects over two million Australians. Consequently, one of the Country s National Health Priorities is to improve our understanding of this condition. Analyses of the asthmatic lung reveal an airway wall that is thickened, an airway lumen that is obstructed and abnormal spasmogenicity of the airway smooth muscle: processes that collectively contribute to both acute and chronic respiratory dysfunction. Asthmatics develop an immune response that is biased toward production of allergy-related T helper 2 cytokines of which interleukin (IL)-13 is a potent mediator of disease. However, the molecular processes linking IL-13 with abnormal airway wall changes are unclear. To identify previously uncharacterised IL-13-related molecules, we used a protein profiling approach that identified a novel lectin (carbohydrate-binding protein) termed Ym2, which is secreted abundantly into the airway fluid of mice in which allergic airways disease has been induced. Preliminary studies suggest that Ym2 is an intermediary of IL-13 that is involved in respiratory dysfunction. This project aims to work out how Ym2 interacts with the molecules and cells of the respiratory tract to regulate allergic disease. Specific inhibitors of Ym2 will be developed to examine what happens to allergic responses when Ym2 can t function; transgenic mice will be developed to determine if we see features of allergy when Ym2 is over-expressed in the normal lung, and human samples will be screened to identify the human counterpart of Ym2 and whether this counterpart is secreted into the lung fluid of asthmatics. Defining the mechanism by which Ym2 regulates the pathogenesis of allergic disease will not only contribute to our basic understanding of the processes underlying asthma pathology, but also generate new information for better design of therapeutics directed against specific mediators of this debilitating and widespread disease.Read moreRead less
Airway Virus Infection, Protease-activated Receptors And Microvascular Permeability
Funder
National Health and Medical Research Council
Funding Amount
$421,527.00
Summary
Asthma is an inflammatory airway disease which kills about 800 Australians each year and otherwise afflicts millions of children and adults in all age groups. Respiratory tract viral infections trigger inflammation and asthma. We believe that this is caused by the loss of naturally protective, bronchodilator and anti-inflammatory substances such as prostaglandin E2 and increased production of asthma promoting substances such as endothelins. Both of these substances are made by the epithelial lin ....Asthma is an inflammatory airway disease which kills about 800 Australians each year and otherwise afflicts millions of children and adults in all age groups. Respiratory tract viral infections trigger inflammation and asthma. We believe that this is caused by the loss of naturally protective, bronchodilator and anti-inflammatory substances such as prostaglandin E2 and increased production of asthma promoting substances such as endothelins. Both of these substances are made by the epithelial lining cells of the bronchi where viruses grow. This project will assess the influence of respiratory tract virus infection on epithelial mechanisms for the production of PGE2 and endothelins. Respiratory viral infections are accompanied by airway inflammation and thus by elevated microvascular permeability and oedema which exacerbates obstruction in asthma. We will measure airway microvascular permeability changes during viral infection and assess the protective effect of stimulating protease-activated receptors which increases PGE2 production. The impact of the PAR system on the integrity of microvascular tissue and on epithelial endothelin production has not been previously investigated. In addition, the influence of respiratory tract viral infection on PAR function in this system is also unknown, but is potentially of great importance to our understanding of the behaviour and regulation of this natural bronchoprotective pathway. This work may lead to the use of novel PAR activators as combined bronchodilator-anti-inflammatory therapies in asthma.Read moreRead less