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
Role Of P2X7 In Innate And Adaptive Immunity To Mycobacterial Infections
Funder
National Health and Medical Research Council
Funding Amount
$472,500.00
Summary
Tuberculosis remains an enormous global health problem. Some 32% of the world s population are infected, with over 2 million persons dying each year. It is not well understood why some infected individuals develop clinical disease yet others remain healthy, but many cases are due to reactivation of dormant organisms lying within a specialized white cell, the macrophage. We know that declining socio-economic conditions, HIV co-infection, and some genetic risk factors such as HLA type contribute t ....Tuberculosis remains an enormous global health problem. Some 32% of the world s population are infected, with over 2 million persons dying each year. It is not well understood why some infected individuals develop clinical disease yet others remain healthy, but many cases are due to reactivation of dormant organisms lying within a specialized white cell, the macrophage. We know that declining socio-economic conditions, HIV co-infection, and some 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 of an infected individual developing disease. We have recently shown that the tuberculosis bacteria can be killed by the addition of a natural compound, ATP, to infected macrophages. This process occurs when ATP activates the P2X7 receptor leading to mycobacterial killing. We have identified several polymorphisms (mutations) in the P2X7 receptor. In individuals with one particular polymorphism, designated A1513C, these people do not respond to ATP and do not kill tuberculosis using this pathway. TB patients who are heterozygous for the A1513C polymorphism show approximately a 50% reduction in mycobacterial killing. We have preliminary evidence that this A1513C polymorphism is expressed at an over represented frequency in TB patients we have tested, suggesting that having this polymorphism may increase your risk of developing tuberculosis. The aim of this project is two fold. One, we will investigate the functioning of this receptor, determining how the P2X7 receptor is activated and how it interacts with other molecules in the immune system to kill tuberculosis. Secondly we shall determine if polymorphisms in the P2X7 receptor are a risk factor for the development of tuberculosis and leprosy disease.Read moreRead less
Genetic Modulation Of The Host Response To Pulmonary TB
Funder
National Health and Medical Research Council
Funding Amount
$540,273.00
Summary
Tuberculosis (TB) is an enormous global health problem. The World Health Organisation estimates that TB, which is caused by infection with the bacteria Mycobacterium tuberculosis, infects 2 billion individuals, leading to 2 million deaths and 8 million new cases of disease per year. Most TB disease is not manifest at the time of infection, but is a reactivation of latent disease in people who do not completely eradicate the primary infection. In a latent infection an effective chronic host respo ....Tuberculosis (TB) is an enormous global health problem. The World Health Organisation estimates that TB, which is caused by infection with the bacteria Mycobacterium tuberculosis, infects 2 billion individuals, leading to 2 million deaths and 8 million new cases of disease per year. Most TB disease is not manifest at the time of infection, but is a reactivation of latent disease in people who do not completely eradicate the primary infection. In a latent infection an effective chronic host response contains dormant TB organisms inside activated macrophages. Cells are recruited to wall off infected macrophages and specific T cells continually induce the activate state with minimal tissue damage (immunopathology). Although currently available antibiotics can kill TB organisms, the treatment is prolonged, expensive, difficult to administer in poorly resourced regions and not effective against multi-drug resistant organisms. New therapies to treat both active disease and prevent reactivation in individuals who are latently infected are urgently required. This proposal will address this problem using a novel approach, namely gene manipulation to augment host immunity to TB and limit concurrent immunopathology. We will construct vectors to increase expression of the key immune molecules, the T lymphocyte activating cytokines IL-12 and IL-23, and the macrophage effector molecules LRG-47 and Indoleamine 2,3-Dioxygenase (IDO). These molecules are known to be involved in TB killing. We will determine if increasing their expression increases the killing capacity of TB-infected macrophages and we will examine how these molecules interact to aid clearance of the TB bacilli. This internationally competitive grant will further our detailed understanding of the complex immune response to TB organisms and lead to the development of novel therapies to treat TB infection and prevent reactivation of latent disease.Read moreRead less
NOD1 Sensing Of H. Pylori Peptidoglycan Promotes Cell Survival And Bacterial Persistence
Funder
National Health and Medical Research Council
Funding Amount
$792,492.00
Summary
The bacterium H. pylori lives in the stomach of half the world’s population and is a major cause of human disease, including peptic ulcers and stomach cancer. This project will investigate how H. pylori is able to manipulate the host immune system by modifying the composition of its outside layer (the cell wall). In so doing, H. pylori causes changes in cells of the stomach lining that allow the bacterium to persist, but that also may predispose the host to cancer.
We seek to gain a detailed understanding of how interactions between the West Nile virus proteins and host factors involved in the IFN response determine the outcome of virus infection. Better understanding of the mechanisms employed by this highly pathogenic virus to disable the mammalian host's IFN response will have wider implications for our understanding of other human diseases such as cancer, autoimmunity and provide new avenues for design of efficient antiviral and anticancer therapies.
Toxoplasma Gondii Infection Of Human Retinal Pigment Epithelium
Funder
National Health and Medical Research Council
Funding Amount
$460,668.00
Summary
Ocular toxoplasmosis is a vision-threatening parasitic eye infection that is common in Australia and worldwide. No treatment cures the disease. This work will characterize cellular and molecular events occuring in the eye during an infection, which is an important first step toward the development of more effective treatments for patients with the condition.
Several members of the Flaviviridae family are major pathogens of humans including dengue (DEN), yellow fever (YF), tick-borne encephalitis (TBE), Murray valley encephalitis (MVE), Japanese encephalitis (JE), and hepatitis C virus (HCV). An Australian flavivirus Kunjin (KUN), however, appears to be naturally attenuated and does not cause an overt disease in humans. In contrast, genetically and antigenically closely related to KUN, New York strain of West Nile virus (NY WN) has already caused ~50 ....Several members of the Flaviviridae family are major pathogens of humans including dengue (DEN), yellow fever (YF), tick-borne encephalitis (TBE), Murray valley encephalitis (MVE), Japanese encephalitis (JE), and hepatitis C virus (HCV). An Australian flavivirus Kunjin (KUN), however, appears to be naturally attenuated and does not cause an overt disease in humans. In contrast, genetically and antigenically closely related to KUN, New York strain of West Nile virus (NY WN) has already caused ~500 deaths and over 20,000 registered infections since its emergence in North America in 1999, including 223 deaths and 9122 infections in 2003 alone. Recent studies with DEN indicated that flaviviruses may interfere with early steps of IFN-signalling pathway. The type I Interferon (IFN) response is the first line of defence against viral infections and many viruses have developed different strategies to counteract this response in order to ensure their survival in the infected host. In this grant we seek to exploit our extensive understanding of the molecular biology of KUN virus and the contrasting behaviour of KUN and NY WN viruses to gain an understanding of the role of flavivirus-mediated suppression of host anti-viral IFN response in virus-host relationships and its importance in determining virus virulence.Read moreRead less