Functional And Structural Relationships Of The Peripheral Airways In Chronic Asthma
Funder
National Health and Medical Research Council
Funding Amount
$318,917.00
Summary
It is now considered that airway wall thickening (airway remodeling), a consequence of persistent airway inflammation in asthmatics, significantly contributes to the symptoms and risk of death from asthma. Despite recent advances in the field, there are still many clinically relevant questions that have not been addressed. Some important issues still to be elucidated are: What is the precise sequence of tissue changes in remodeling? Which components of remodeling are reversible in the absence of ....It is now considered that airway wall thickening (airway remodeling), a consequence of persistent airway inflammation in asthmatics, significantly contributes to the symptoms and risk of death from asthma. Despite recent advances in the field, there are still many clinically relevant questions that have not been addressed. Some important issues still to be elucidated are: What is the precise sequence of tissue changes in remodeling? Which components of remodeling are reversible in the absence of allergen provocation? At what point does airway remodeling become irreversible? Does early intervention with anti-inflammatory medication have long term benefits in terms of reducing long-term remodeling? As there have been few appropriate models for addressing these types of remodeling issues, we propose to utilise a large animal model for chronic asthma to address these questions. One of the main focuses of this proposal is to identify biomarkers or functional indices of the different stages of remodelling. The sheep model is well placed to achieve these objectives given that the structure, physiology and asthma pathophysiology of sheep airways is similar to human airways. The novel experimental design is to expose four spatially separate lung regions (segments) in individual sheep with different durations of repeated weekly doses of HDM. The strength of the proposal is that lung function and structure of challenged segments from successive stages of remodeling can be assessed in one sheep. A separate experiment will examine how lung structure and function return to normal in chronically HDM-treated lung segments over successive months after exposure to HDM ceases. It is expected that information gained from this research will lead to a greater fundamental understanding of disease mechanisms in chronic asthma. This will increase the chances of improving current treatments, and allows for new strategies to be devised for treating asthma more effectively.Read moreRead less
Novel Candidate Genes, Lung Function And Allergic Airways Disease
Funder
National Health and Medical Research Council
Funding Amount
$581,892.00
Summary
We propose to study airway remodelling (structural changes to the airway) and in asthma using human samples and rodent models of asthma. We are particularly interested in investigating the role of trefoil peptide 2 and relaxin, two genes identified as determining lung function. To do this we need to understand the mechanisms of airway remodelling and its impact on disease severity in the patient. A strength of this study is availability of samples from a large study of human asthma.
How Do Thick Airway Walls Affect Airway Hyperresponsiveness In Asthma?
Funder
National Health and Medical Research Council
Funding Amount
$382,538.00
Summary
Asthmatic airways narrow too easily, a characteristic called airway hyperresponsiveness (AHR). To understand the cause of asthma we need to understand the cause of AHR. Thickened airway walls could amplify airway narrowing and increase AHR. However, thick airway walls are also stiff, and stiff walls could reduce narrowing and AHR. This project will examine the relationships between AHR and airway wall thickness and stiffness during and after treatment that reduces airway wall thickness.
Is Asthma In The Elderly A Disease Of The Peripheral Airways?
Funder
National Health and Medical Research Council
Funding Amount
$502,437.00
Summary
Elderly asthmatics have poorer clinical outcomes compared with younger asthmatics. The reasons for this are unclear but may involve age-related changes in the disease itself. In this project we aim to show that asthma in the elderly is dominated by abnormalities of very small peripheral airways, in contrast to younger patients where the abnormalities occur in larger airways. The results will provide the basis for new and better targeted treatment strategies for asthma in the elderly.
Does The Pattern Of Ventilation Distribution Predict Airway Hyperresponsiveness?
Funder
National Health and Medical Research Council
Funding Amount
$256,973.00
Summary
The tendency for airways to narrow too easily when stimulated is called airway hyperresponsiveness (AHR). AHR is an important feature of asthma, but it also occurs in other diseases, such as chronic obstructive pulmonary disease (COPD) - an airway disease caused by smoking, and cystic fibrosis. People who have AHR have more severe respiratory disease, regardless of which disease they have, and are more likely to develop poor lung function in old age and to be hospitalised or die from their disea ....The tendency for airways to narrow too easily when stimulated is called airway hyperresponsiveness (AHR). AHR is an important feature of asthma, but it also occurs in other diseases, such as chronic obstructive pulmonary disease (COPD) - an airway disease caused by smoking, and cystic fibrosis. People who have AHR have more severe respiratory disease, regardless of which disease they have, and are more likely to develop poor lung function in old age and to be hospitalised or die from their disease. If we can understand the causes of AHR we will have a better understanding of why some people with respiratory disease have poor outcomes. We have recently discovered that, in asthma, there is a very close relationship between AHR and the uneven distribution of air within the lungs. We believe that structural changes in the airways that cause this uneven distribution make the airways prone to AHR. This raises the possibility that factors that cause uneven ventilation in other respiratory diseases might also predispose the airways to AHR. If this is true, it suggests that there is a single physiological basis for AHR in a range of different diseases, and would allow us to focus research more closely on the causes of uneven ventilation. In this project we will measure the relationship between AHR and uneven ventilation in people with asthma, COPD or cystic fibrosis. The study is important because older people with asthma, particularly those with permanently narrowed airways, are likely to have more structural changes in their airways than young asthmatics, whereas people with COPD and cystic fibrosis have a different pattern of both structural changes and airway inflammation from that in asthma. The study will tell us whether there is a consistent relationship between AHR and uneven ventilation. If so, this would be extremely strong evidence that the factors that cause uneven ventilation contribute to AHR, and will point the way to studies of new treatments.Read moreRead less
Response Of Human Airways To Deep Inflation In Health And Disease
Funder
National Health and Medical Research Council
Funding Amount
$281,037.00
Summary
The trachea and bronchi contain muscle that when it contracts narrows the air passages and makes it harder to breath. In healthy people taking a deep breath relaxes this airway muscle and improved breathing. However, in people who suffer from asthma and chronic airflow obstruction deep breaths do not have the normal relaxing actions on airway contraction. This study will use lung removed as part of surgery for lung cancer to study how the relaxing actions of deep breathing work in human airways.
Ventilation Heterogeneity And Airway Remodelling In Asthma
Funder
National Health and Medical Research Council
Funding Amount
$522,586.00
Summary
Asthma is a common and important as a cause of significant symptoms and even death. Associated with asthma is narrowing and stiffening of the arways which causes uneven ventilation of the lungs and reduced lung function. We have developed a new technique of imaging the lungs, as well as new lung function tests which measure uneven ventilation and stiffening of airways. This will help us design better medications, and help predict those who are at risk or severe asthma and death.
In the asthmatic lung structural changes, such as increased deposition of proteins which form the scaffolding of the airways (the extracellular matrix proteins), and an increased mass of bronchial smooth muscle cells occur. Many of these critical structural changes are not reversed or prevented with current asthma therapy, thus we need to investigate, by using lung cells and tissues , why they happen and how we can prevent them.
Novel Neuromechanical Measurements Of The Human Upper Airway In Health And Disease
Funder
National Health and Medical Research Council
Funding Amount
$543,728.00
Summary
Obstructive sleep apnea (OSA) is a common condition, in which the upper airway repeatedly collapses during sleep, causing the oxygen concentration in the blood to drop, carbon dioxide to rise, and the person to arouse in order to re-establish adequate oxygen supply. Consequences of OSA include increased daytime sleepiness, increased risk of accidents, and increased risk of cardiovascular diseases. It most commonly affects middle-aged males, but is also seen in the broader population. OSA is asso ....Obstructive sleep apnea (OSA) is a common condition, in which the upper airway repeatedly collapses during sleep, causing the oxygen concentration in the blood to drop, carbon dioxide to rise, and the person to arouse in order to re-establish adequate oxygen supply. Consequences of OSA include increased daytime sleepiness, increased risk of accidents, and increased risk of cardiovascular diseases. It most commonly affects middle-aged males, but is also seen in the broader population. OSA is associated with obesity and specific shapes of the upper airway and facial structure. These anatomical factors can be compensated for while awake but inadequate activity of the muscles surrounding the upper airway during sleep contributes to an increased predisposition of the airway to collapse. Airway collapse occurs when the muscles are unable to withstand the low pressures in the airway and collapse, obstructing the airway. This project will measure the stiffness and motion of the muscles surrounding the airway, in healthy people and those with OSA, to determine how these influence airway collapsibility. We will use two novel non-invasive Magnetic Resonance Imaging (MRI) techniques, MR Elastography, and MR tagging which will allow us to quantify the airway stiffness, or elasticity, and its motion (deformation). These will be the first direct measurements of the upper airway elasticity and deformation in humans. We will also measure how various treatments, such as CPAP therapy and mandibular advancement affect airway elasticity and deformation, so that their mechanisms can be better understood. This may also explain why some patients do not benefit from these therapies. These studies may lead to new diagnostic and treatment modalities, as well as gaining important insights into the basic mechanisms of airway collapse in humans.Read moreRead less