Assessment Of Airway Smooth Muscle Hypertrophy In Asthma And Chronic Obstructive Pulmonary Disease (COPD)
Funder
National Health and Medical Research Council
Funding Amount
$298,055.00
Summary
Asthma and chronic obstructive pulmonary disease (COPD) are common in the Australian community. The cause of asthma is unknown and although COPD is most often due to smoking cigarettes it remains unknown why it develops only in some smokers and in some non-smokers. The pathology of asthma and COPD includes increased thickness of the airway smooth muscle layer. In asthma this is associated with relatively normal airway lumen size and intermittent, excessive airway narrowing whereas in COPD it is ....Asthma and chronic obstructive pulmonary disease (COPD) are common in the Australian community. The cause of asthma is unknown and although COPD is most often due to smoking cigarettes it remains unknown why it develops only in some smokers and in some non-smokers. The pathology of asthma and COPD includes increased thickness of the airway smooth muscle layer. In asthma this is associated with relatively normal airway lumen size and intermittent, excessive airway narrowing whereas in COPD it is associated with fixed narrowing of the airway lumens. The increased smooth muscle layer might result from more or bigger smooth muscle cells or from more connective tissue (matrix) between the muscle cells. This project aims to determine which of these 3 factors causes the increased thickness of the smooth muscle layer in asthma and COPD. We hypothesise that in asthma there are more muscle cells and more matrix, and that in COPD there is only more matrix. These differences would account for the different behaviour of the airways in asthma and COPD. Currently there is no useful or practical method to measure the amount of matrix in the airway wall, especially in the smooth muscle. This project will study the amount of matrix and muscle in very thin airway sections (< 1 m) from a large number of cases of asthma and COPD to allow, for the first time, accurate assessment of the fractions of matrix and muscle in the smooth muscle layer, since they barely overlap on these thin sections. The results of this study are important because they will: differentiate between mechanisms of increased thickness of the airway smooth muscle layer in asthma and COPD and therefore identify different prevention and treatment strategies; help to develop a method of monitoring airway remodeling in airway diseases that can be applied to bronchial biopsies.Read moreRead less
Pathophysiological Correlates In Smokers And Smoking-related Chronic Obstructive Pulmonary Disease (COPD)
Funder
National Health and Medical Research Council
Funding Amount
$283,500.00
Summary
Smoking-related chronic airway narrowing (COPD) is a common and major illness. Research on the characteristics of the actual pathological process in the airways in smokers and COPD using direct tissue sample is relatively new. Data is currently limited and rather contradictory. In this grant we will recruit a spectrum of smokers and COPD patients typical of those in the Australian community and will be undertaking a detailed analysis of the cellular and some vascular structural changes in the ai ....Smoking-related chronic airway narrowing (COPD) is a common and major illness. Research on the characteristics of the actual pathological process in the airways in smokers and COPD using direct tissue sample is relatively new. Data is currently limited and rather contradictory. In this grant we will recruit a spectrum of smokers and COPD patients typical of those in the Australian community and will be undertaking a detailed analysis of the cellular and some vascular structural changes in the airway wall. Both cellular and vascular changes will be related to the fixed and reversible component of airway obstruction. Reversible changes with smoking cessation will be studied. A very novel feature will be a preliminary assessment of the utility of proteomics for assessment of airway pathology.Read moreRead less
Characterisation Of PAR2 Knockout And Transgenic Mice: Towards Gene Therapy For Epithelia Based Inflammatory Diseases
Funder
National Health and Medical Research Council
Funding Amount
$486,943.00
Summary
Debilitating and sometimes fatal diseases like asthma and rheumatoid arthritis urgently require new approaches for their effective management and hopefully, cure. We have recently discovered that the airways posses a powerful and naturally-occuring protective mechanism which is regulated by unique molecules in the membranes of the lining cells of the air passages. These molecules are called protease-activated receptors, or PARs, and are also found on cells lining the inner surfaces of blood vess ....Debilitating and sometimes fatal diseases like asthma and rheumatoid arthritis urgently require new approaches for their effective management and hopefully, cure. We have recently discovered that the airways posses a powerful and naturally-occuring protective mechanism which is regulated by unique molecules in the membranes of the lining cells of the air passages. These molecules are called protease-activated receptors, or PARs, and are also found on cells lining the inner surfaces of blood vessels and joints as well as in skin. We are fortunate to have strains of mice - a species in which the PAR-mediated protective mechanism is well developed - in which the gene for the most important of the PARs found in the lung, PAR2, is missing. These animals are called PAR2 'knock-outs'. We also have another strain of mouse in which the human PAR2 gene has been inserted back into PAR2 knock-out mice. These animals will allow us to determine the importance of PAR2 in protection against asthma, arthritis, vascular disease and deficiencies in skin healing, as well as how PAR2 might be a more effective protective agent in mice rather than humans. Thus, modification of the human gene to make the protective system work as effectively as in the mouse might provide an effective therapy or cure for diseases of the lungs, joints and skin as well as in vascular diseases.Read moreRead less
Early Events In Arteriolar Remodeling: Adaptation To Prolonged Vasoconstriction
Funder
National Health and Medical Research Council
Funding Amount
$415,750.00
Summary
Small arteries, while acutely responding to their environment with changes in diameter to regulate local blood flow and pressure, also undergo structural adaptation or remodelling. These events occur over a range of time-frames and involve both non-genetically and genetically regulated events. Thus a contractile event, while initially decreasing vessel diameter, also activates longer time frame processes which can span from rearrangment of cellular junctions-contacts to overt structural changes ....Small arteries, while acutely responding to their environment with changes in diameter to regulate local blood flow and pressure, also undergo structural adaptation or remodelling. These events occur over a range of time-frames and involve both non-genetically and genetically regulated events. Thus a contractile event, while initially decreasing vessel diameter, also activates longer time frame processes which can span from rearrangment of cellular junctions-contacts to overt structural changes within the vessel wall (for example thickening of the muscle layer). These adaptive processes may enable the forces of contraction to be maintained without continued energy expenditure and damage to the vessel per se. However, they can also contribute to long-term alterations in the control of blood pressure and perhaps contribute to states of hypertension as well as other common vascular diseases. For these studies we will use arterioles, isolated by microsurgical techniques, together with sophisticated computer and video-based approaches. These techniques allow arterioles to be studied under controlled conditions and relevant biochemical measurements performed. We will also use a cell model where cultured cells will be studied after defined periods of mechanical stimulation (for example stretch). Cells will be probed using a novel microscopic technique (atomic force microscopy) which enables the cell membrane to be studied with respect to changes in composition as well as physical characteristics (for example stiffness). The studies are relevant to our understanding of the normal adaptive processes occurring within blood vessels to control blood flow and pressure. The studies are also of direct relevance to our understanding of common vascular disease states including hypertension, complications of diabetes and chronic inflammatory disorders.Read moreRead less
While many cases of asthma are mild, severe cases require extensive health care resources and are virtually unresponsive to conventional treatment. This project will investigate whether specific compounds released from the airway are able to cause lung damage and airway abnormalities similar to that in severe asthma. We will investigate whether these changes are responsive to conventional therapy and investigate a potential treatment for regaining this responsiveness in severe asthma.
Mechanisms Of Airway Narrowing In Eosinophilic And Non-eosinophilic Asthma
Funder
National Health and Medical Research Council
Funding Amount
$500,593.00
Summary
Asthma is associated with excessive airway narrowing, increased thickness of the airway wall and inflammation, most typically with eosinophils. However, 50% of cases have few eosinophils and respond less well to current treatments. This project will examine differences in airway structure between patients with or without eosinophils, using post-mortem tissue, as part of an international research collaboration.
Mannitol In The Assessment Of Bronchial Responsiveness In Airway Disease
Funder
National Health and Medical Research Council
Funding Amount
$365,250.00
Summary
The airways of people with asthma respond by narrowing too easily and too much to a wide range of stimuli. The tests most commonly used to measure airway responsiveness in asthma are the pharmacological agents methacholine and histamine. When inhaled, they act directly on bronchial muscle causing it to contract and hence the airways to narrow. We have developed a non-pharmacological test using a dry powder of a sugar - mannitol. When inhaled, mannitol causes narrowing of the airways in asthmatic ....The airways of people with asthma respond by narrowing too easily and too much to a wide range of stimuli. The tests most commonly used to measure airway responsiveness in asthma are the pharmacological agents methacholine and histamine. When inhaled, they act directly on bronchial muscle causing it to contract and hence the airways to narrow. We have developed a non-pharmacological test using a dry powder of a sugar - mannitol. When inhaled, mannitol causes narrowing of the airways in asthmatics but little or no effect in healthy subjects. Many asthmatics respond to mannitol even when they have few symptoms of asthma. Mannitol causes the airways to narrow 'indirectly' by causing the release of substances from inflammatory cells in the airways (e.g. histamine, leukotrienes and prostaglandins) that cause the muscle to contract. After the inflammation has cleared, either by treatment with inhaled steroids or spontaneously, the response to mannitol is close to healthy subjects. Thus the response to mannitol depends on the presence of inflammation and loss of responsiveness means resolution of inflammation. The significance of this is that the mannitol test may be used as an 'inflammometer'. It would be important if airway responsiveness to mannitol could be used to identify individuals with airway diseases other than asthma, (chronic bronchitis, and chronic obstructive lung disease) who could benefit from treatment with inhaled steroids. This would be significant as there is currently no test to identify those individuals and there are unwanted effects from using steroids. Further, it may be possible to use mannitol to identify individuals with other inflammatory diseases who may be at risk of developing asthma. Some people with asthma, chronic bronchitis and chronic obstructive lung disease have increased levels of oxidative stress. We wish to identify those people and to measure change after treatment with steroids.Read moreRead less
Increased Airway Smooth Muscle Mass As An Independent Determinant Of Asthma Pathogenesis And Severity
Funder
National Health and Medical Research Council
Funding Amount
$409,966.00
Summary
Asthma is a major health burden to the community. The most common form of the disease is allergic asthma and it is thought that allergic inflammation drives associated airway abnormalities including increased airway smooth muscle (ASM) mass. This study tests a new hypothesis that airway abnormalities and allergy have separate origins but combine to produce allergic asthma, and it’s the individuals with the greatest amount of ASM who develop clinically severe asthma.