Cell Migration And Granuloma Formation In The Expression Of Protective Immunity Against Tuberculosis In The Lung
Funder
National Health and Medical Research Council
Funding Amount
$212,036.00
Summary
Tuberculosis (TB) remains an enormous problem worldwide and a continuing health problem in Australia. Most TB is not due to disease at the time of infection, but is a reactivation of dormant infection in people who have never eradicated the organisms. This study will investigate, in mice, how TB is initially contained within the lungs and how reactivation occurs. All mice infected with TB control the infection initially. T lymphocytes are activated and T cells and macrophages are recruited to th ....Tuberculosis (TB) remains an enormous problem worldwide and a continuing health problem in Australia. Most TB is not due to disease at the time of infection, but is a reactivation of dormant infection in people who have never eradicated the organisms. This study will investigate, in mice, how TB is initially contained within the lungs and how reactivation occurs. All mice infected with TB control the infection initially. T lymphocytes are activated and T cells and macrophages are recruited to the lung, migrate into lung tissue and surround infected lung macrophages forming granulomas. We have identified mice that progress to TB disease early after infection (early progressor strains) and another strain that progresses later (late progressors). In the early progressors, lymphocytes are not as efficiently recruited to the lung and do not form the tight granulomas seen in late progressor strains. We plan to make a detailed comparison of these two strains looking at differences in cell-membrane molecules and the soluble messenger molecules (cytokines and chemokines) that provide the signals that attract cells to the lung and direct them to surround infected lung macrophages. By comparing events in early and late progressor strains we will find which molecules are required for initial and long-term containment, and which events lead to breakdown of granulomas and reactivation of disease. In addition, we recently showed that one cytokine, tumour necrosis factor (TNF), is essential for cell migration through the lung. By comparing normal mice with mice deficient in TNF we will study the downstream effects regulated by TNF, particularly the chemokine messengers that direct cell movement into granulomas. By identifying the molecules and cells required to control TB we plan to design improved vaccines to prevent TB infection and improved treatments to prevent disease reactivation.Read moreRead less
Membrane TNF And Lymphotoxin Control Of Chemokine Induction And Inflammation In Tuberculosis
Funder
National Health and Medical Research Council
Funding Amount
$457,500.00
Summary
Tuberculosis (TB) remains an enormous problem worldwide. Most TB is not due to disease at the time of infection, but is a reactivation of dormant disease in people who have never completely eradicated the organisms. Macrophages containing dormant TB organisms are located in lesions called granulomas. Granulomas consist of TB-infected macrophages surrounded by T lymphocytes that actively contain the infection. T lymphocytes prevent the growth of TB organisms in the macrophages and so prevent wide ....Tuberculosis (TB) remains an enormous problem worldwide. Most TB is not due to disease at the time of infection, but is a reactivation of dormant disease in people who have never completely eradicated the organisms. Macrophages containing dormant TB organisms are located in lesions called granulomas. Granulomas consist of TB-infected macrophages surrounded by T lymphocytes that actively contain the infection. T lymphocytes prevent the growth of TB organisms in the macrophages and so prevent widespread infection that would cause illness in the host. Activated T lymphocytes that recognise TB-infected macrophages circulate in blood, are recruited from blood capillaries into the lung, migrate through the tissue and co-localise with infected macrophages. Soluble molecules (cytokines and chemokines) are known to provide the signals that direct cell migration and activation events. This study will investigate in detail cytokines and chemokines that are involved, the cells that produce then and where these cells are located in the lung. We recently showed that tumour necrosis factor (TNF), and the related cytokine lymphotoxin (LT), are essential for lymphocyte migration through the lung. These belong to a family of related molecules that signal through the same panel of receptors and regulate chemokine expression and inflammation. In this study we will use genetically manipulated mice that lack TNF. LT or other family members or that express only membrane-bound TNF to study how each affects production of different chemokines, chemokine receptors and other molecules. Since there are at least 50 known chemokines and 17 chemokine receptors we will use microarray technology to simultaneously screen changes in expression of several thousand genes and laser microdissection to study cells from different location in infected lungs. Understanding signals necessary to direct T cells into granulomas may facilitate new treatments to prevent TB reactivation disease.Read moreRead less
Investigating The Mechanisms Of Regulation Of Mycobacterial Cell Wall Biosynthesis
Funder
National Health and Medical Research Council
Funding Amount
$597,349.00
Summary
Tuberculosis (TB) kills around two million people each year while the causative bacterial species, Mycobacterium tuberculosis, infects one-third of the entire human population. An alarmingly high rate of TB exists in Australia's indigenous population. This proposal aims to identify and characterise essential processes involved in synthesis of the outer coat of the bacterium which are potential targets for new drugs for the treatment of this devastating disease.
Genetic Adaptations Of Mycobacterium Tuberculosis For Intracellular Survival
Funder
National Health and Medical Research Council
Funding Amount
$187,677.00
Summary
Tuberculosis (TB) remains a significant global public health problem and new approaches to its treatment and prevention are urgently needed. The disease is caused by infection with Mycobacterium tuberculosis, a slow growing organism that lives within cells. How it adapts to survive in this intracellular environment is unknown. Recently the complete genome of M. tuberculosis was sequenced and new techniques developed for manipulating its genes. We plan to use these techniques to identify genes th ....Tuberculosis (TB) remains a significant global public health problem and new approaches to its treatment and prevention are urgently needed. The disease is caused by infection with Mycobacterium tuberculosis, a slow growing organism that lives within cells. How it adapts to survive in this intracellular environment is unknown. Recently the complete genome of M. tuberculosis was sequenced and new techniques developed for manipulating its genes. We plan to use these techniques to identify genes that are more active within the cells. Genes are controlled by short sequences of preceding DNA called promoters. If these promoters are randomly placed in front of readily identifiable reporter genes and inserted into a suitable host strain, it is possible to select for those promoters expressed only inside cells and then identify the promoter and its gene by sequence analysis. We plan to use two types of reporter genes. First, we shall place the M. tuberculosis DNA containing promoters before the gene for a naturally fluorescent protein within the M. bovis BCG host strain and then infect macrophages. If the promoters are switched on inside the cell, the macrophages will become green and can be selected and the promoter identified. After several rounds of selection the promoter is isolated and identified. Second, we shall select the promoters by their ability to produce a protein that is on the surface of the bacterium. We will use these intracellular genes to make better vaccines against TB. Genes that enhance intracellular survival may contribute to the virulence of the TB organism. By removing these genes we can make an attenuated organism suitable as a vaccine. We will test for reduced virulence by growth inside cells in mice. We will also use the intracellular promoter to improve the current BCG vaccine. Proteins expressed inside the cell may also be targets for new TB drugs.Read moreRead less
Genetics And Biochemistry Of Biosynthesis Of The Cell Wall Of Mycobacteria
Funder
National Health and Medical Research Council
Funding Amount
$260,831.00
Summary
Mycobacteria commolnly cause human disease. The major killer in the group is Mycobacterium tuberculosis which annually causes millions of deaths from tuberculosis (TB) worldwide. Another pathogen from this group is Mycobacterium avium which often infects immunosuppressed people such as those with advanced HIV-AIDS. Mycobacteria have evolved a specialised wall that surrounds their cells which protects them from chemical attack from antibiotics and helps them to establish infections. The major ant ....Mycobacteria commolnly cause human disease. The major killer in the group is Mycobacterium tuberculosis which annually causes millions of deaths from tuberculosis (TB) worldwide. Another pathogen from this group is Mycobacterium avium which often infects immunosuppressed people such as those with advanced HIV-AIDS. Mycobacteria have evolved a specialised wall that surrounds their cells which protects them from chemical attack from antibiotics and helps them to establish infections. The major antibiotic used for TB stops cells from synthesising the protective layer thereby making them very vulnerable to human immune defences. Unfortunately, resistance to this antibiotic is common and new antibiotics are needed to treat mycobacterial infections. We are studying how mycobacteria make the cell wall and are looking for key steps where new drugs might be able to inhibit the process. Our approach is to inactivate genes in the mycobacteria that make the enzymes which control cell wall synthesis. The gene inactivation results in crippled mycobacteria that are unable to make proper cell walls. We analyse the cell wall changes that gene inactivation cause studying the chemical composition of the cell. This helps to identify the steps in cell wall biosynthesis and each step becomes a potential target for new drugs. Each of the weaken mycobacteria can be tested to see how well they can resist antibiotics and to see if they can survive host defences. In this way we can identify which components of the cell wall are critical for them to establish infections and resist antibiotic treatments. Enzymes that participate in the synthesis of such components are prime targets for us to concentrate on to design new antibiotics.Read moreRead less
Cytokine And Macrophage Determinants Of Pulmonary Inflammation During Tuberculosis
Funder
National Health and Medical Research Council
Funding Amount
$455,899.00
Summary
Tuberculosis (TB) infects 33% of the world, causing over 2 million deaths per year. TB disease causes damaging lung pathology and new therapies to treat the infection and moderate inflammation are urgently required. TNF is essential for immunity to TB, acting to modulate inflammation. This grant will determine how soluble and membrane- bound TNF regulate the cellular and cytokine control of TB pathology and may lead to new therapies to limit inflammation in TB and other inflammatory diseases.
Characterization Of Human-specific Anti-microbial Pathways
Funder
National Health and Medical Research Council
Funding Amount
$586,428.00
Summary
The immune system protects us against infectious disease by killing invading microbes or pathogens. Macrophages are white blood cells that are important for the recognition and destruction of pathogens. This project aims to investigate the role of certain genes, which are turned on in macrophages when they sense invading pathogens, in protecting us against infectious diseases such as tuberculosis and gastroenteritis.
Inhibition Of Siderophore Biosynthesis For Tuberculosis Drug Discovery
Funder
National Health and Medical Research Council
Funding Amount
$424,262.00
Summary
Tuberculosis (TB) is responsible for over 2 million deaths globally every year. Despite this alarming statistic, no new TB drugs have reached the market in 40 years. This is despite the emergence of strains of Mycobacterium tuberculosis (the causative agent of TB) that are resistant to currently prescribed drugs. This project aims to discover TB drug leads with a unique mode of action. This will be achieved by preparing compounds that prevent the bacterium from acquiring iron from the host.
KILLING OF MYCOBACTERIUM TUBERCULOSIS IN MACROPHAGES VIA THE P2X7 RECEPTOR
Funder
National Health and Medical Research Council
Funding Amount
$226,320.00
Summary
Tuberculosis remains an enormous global health problem. Some 32% of the world population are infected, with over 1 million persons dying each year. The risk of an infected individual developing clinical disease ranges from 2-23% for their lifetime. We know that both environmental factors, such as declining socio-economic conditions, and genetic risk factors such as HLA type contribute to the likelihood of an individual developing disease, but current known factors are insufficient to fully accou ....Tuberculosis remains an enormous global health problem. Some 32% of the world population are infected, with over 1 million persons dying each year. The risk of an infected individual developing clinical disease ranges from 2-23% for their lifetime. We know that both environmental factors, such as declining socio-economic conditions, and genetic risk factors such as HLA type contribute to the likelihood of an individual developing disease, but current known factors are insufficient to fully account for the risk attributed to genetics. The aim of this project is to investigate another potential risk factor involved in the development of tuberculosis, that of P2X7 receptor function. A natural compound, ATP, when added to macrophages is able to kill tuberculosis organisms residing within the macrophage. This process occurs when ATP activates the P2X7 receptor. We have recently identified a mutation in the P2X7 receptor, which causes a loss of receptor function. Individuals who have this mutation are unable to respond to ATP and hence may be unable to kill tuberculosis. Our studies will determine if the mutation we have identified in the P2X7 receptor prevents or inhibits ATP mediated killing of mycobacteria. Furthermore we will determine the frequency of this mutation in TB patients and the general population to determine if this mutation in the P2X7 receptor is a risk factor for the development of tuberculosis disease.Read moreRead less