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
Mechanisms Of Protease-activated Receptor-2-mediated Bronchoprotection
Funder
National Health and Medical Research Council
Funding Amount
$354,758.00
Summary
The incidence of asthma continues to increase globally, yet there have been few real therapeutic advances. Our research, however, has recently uncovered a novel mechanism that protects the airways from inflammatory diseases like asthma. We have found that the layer of cells that line the airways - the epithelium - acts as a detector of early inflammatory events and releases anti-inflammatory substances. The lungs achieve this level of protection via 'sensor' molecules called receptors which are ....The incidence of asthma continues to increase globally, yet there have been few real therapeutic advances. Our research, however, has recently uncovered a novel mechanism that protects the airways from inflammatory diseases like asthma. We have found that the layer of cells that line the airways - the epithelium - acts as a detector of early inflammatory events and releases anti-inflammatory substances. The lungs achieve this level of protection via 'sensor' molecules called receptors which are located in the epithelium. In the case of our discovery, these receptors are called protease-activated receptors (PARs) to highlight the unique manner in which they are turned on or activated by enzymes called proteases. We have discovered that the epithelium of the lungs stores these enzymes and probably releases them during the inital stages of infection. Once released, these enzymes are detected by PARs on epithelial cells which then release substances that inhibit multiple inflammatory pathways. This mechanism protects the airways from effects that make breathing difficult, as in asthma. We have confirmed that this system provides protection in the airways of intact animals. The purpose of this projects outlined in this application is to examine the effects of activating one PAR, PAR2, on several processes in the lung, in order to characterise the individual events and processes that underlie the protective response. These studies will enable us to determine whether synthetic compounds that activate PAR2 are potential novel compounds for the treatment of diseases like asthma.Read moreRead less
Pharmacological Regulation Of Airway Smooth Muscle Phenotype
Funder
National Health and Medical Research Council
Funding Amount
$276,742.00
Summary
In Australia there is a high incidence of asthma which impairs quality of life and can sometimes cause death if sufficiently severe. The main cause of asthma is the shortening of muscle surrounding the airway passages that cause the narrowing of these tube-like passages. When airway passages narrow a feeling of chest tightness is perceived by the asthmatic patient. When the narrowing is severe the amount of oxygen being delivered to the blood can be reduced to dangerous levels. When there is mus ....In Australia there is a high incidence of asthma which impairs quality of life and can sometimes cause death if sufficiently severe. The main cause of asthma is the shortening of muscle surrounding the airway passages that cause the narrowing of these tube-like passages. When airway passages narrow a feeling of chest tightness is perceived by the asthmatic patient. When the narrowing is severe the amount of oxygen being delivered to the blood can be reduced to dangerous levels. When there is muscle growth in the airways even small amounts of shortening of the muscle can cause severe narrowing of the airway passages. This research will investigate how muscle grows in asthmatic airways and look for new ways to use drugs to treat this muscle growth. We hope to improve drug treatment of asthma by limiting the amount of airway narrowing caused by muscle contraction.Read moreRead less
Epithelium-fibroblast Interactions In Response To Allergic Airway Inflammation
Funder
National Health and Medical Research Council
Funding Amount
$235,526.00
Summary
The airways of an asthmatic patient undergo dramatic structural changes over time. This remodelling is thought to be responsible for producing the changes in lung function that are frequently observed in someone with the disease. However, in contrast to normal wound repair, it is unclear why in the majority of asthmatics, inflammation leads to ongoing remodelling rather than a self limiting healing process. In this context, cells that line the airways (epithelium) as well as cells that sit immed ....The airways of an asthmatic patient undergo dramatic structural changes over time. This remodelling is thought to be responsible for producing the changes in lung function that are frequently observed in someone with the disease. However, in contrast to normal wound repair, it is unclear why in the majority of asthmatics, inflammation leads to ongoing remodelling rather than a self limiting healing process. In this context, cells that line the airways (epithelium) as well as cells that sit immediately beneath them (fibroblasts) are important sources of mediators and structural matrix proteins that contribute to these processes. Under normal conditions, signals from these structural proteins are transmitted to the cells via specific adhesion molecules. However, in asthma epithelial cells are frequently damaged and detached, and fibroblasts appear to proliferate and undergo changes in their appearance. This projects aims to investigate the expression and function of specific cell adhesion molecules in the epithelium and fibroblasts following airway inflammation. Specifically, this proposal aims to determine which adhesion molecules are associated with upregulated proliferation and production of matrix proteins. We will also examine the effects of two novel mediators, thought to play a role in remodelling on the expression and function of these adhesion molecules. Proliferation of these cells and the altered deposition of matrix proteins may be a key feature of airway wall thickening and hyperreactivity that is a characteristic feature of asthma. The balance of deposition and breakdown of matrix proteins is regulated by a variety of mediators. Defining what regulates the expression and activity of adhesion molecules is of fundamental importance in determining how the normal repair processes may evolve into airway wall remodelling.Read moreRead less
Airway Smooth Muscle Contribution To Remodelling In Asthma.
Funder
National Health and Medical Research Council
Funding Amount
$211,320.00
Summary
Asthma is an airway disease that affects more than 10% of adults and 25% of children in Australia and in 1998 caused 675 deaths. The cost to the community is in excess of $720 million a year. The abnormality in asthma is not fully understood, however inflammation, changes to the structure of the airways and excessive airway narrowing are key factors. Inflammation and the allergic reactions which accompany asthma cause fluid to leak from tiny blood vessels in the lung. This fluid and the inflamma ....Asthma is an airway disease that affects more than 10% of adults and 25% of children in Australia and in 1998 caused 675 deaths. The cost to the community is in excess of $720 million a year. The abnormality in asthma is not fully understood, however inflammation, changes to the structure of the airways and excessive airway narrowing are key factors. Inflammation and the allergic reactions which accompany asthma cause fluid to leak from tiny blood vessels in the lung. This fluid and the inflammation are linked to changes in the airway which include structural protein deposition - breakdown and an overgrowth of the smooth muscle that lines the walls of the airway. Our work is focussed on understanding the relationship between the structural protein deposition - breakdown and excess muscle growth. We also hope to gain a better understanding of the way asthma treatments combat these changes in the asthmatic airways.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
Modulation Of Asthmatic Airway Inflammation By Activation Of Epithelial Proteinase Activated Receptors
Funder
National Health and Medical Research Council
Funding Amount
$188,912.00
Summary
Children and adults feel the symptoms of asthma because their airways close up too easily. We have discovered a new mechanism that the healthy lung uses to keep airways open. The epithelial cells which line the airway release an enzyme that cuts of a small part of another protein, called a PAR receptor, that sits on the same cell. When this happens the epithelial cell releases relaxing substances from their lower surface. The relaxing substances keep the airways open. This grant application is d ....Children and adults feel the symptoms of asthma because their airways close up too easily. We have discovered a new mechanism that the healthy lung uses to keep airways open. The epithelial cells which line the airway release an enzyme that cuts of a small part of another protein, called a PAR receptor, that sits on the same cell. When this happens the epithelial cell releases relaxing substances from their lower surface. The relaxing substances keep the airways open. This grant application is designed to test whether the relaxing system also stops the airways from developing inflammation. If the relaxing system does this we will be able to use the knowlege we have that lets us activate the PAR receptors artificially to design new types of drugs. These drugs would be better than existing asthma drugs because they would prevent inflammation and relax the airways at the same time. These drugs could also be useful in other lung diseases such as chronic bronchitis.Read moreRead less