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
Tumour B-cells From Lymphomas Are Resistant To ATP-mediated Apoptosis Due To Non-functional P2X7 Receptors
Funder
National Health and Medical Research Council
Funding Amount
$226,320.00
Summary
Adenosine triphosphate (ATP) is an important constituent normally present inside cells. When added to normal lymphocytes (or released by cells lining the vessel wall or in lymph nodes), ATP acts from outside these cells to open a pore as well as activate an enzyme which digests the lipid envelope of the cell. This loss of lipid covering of the cell produces a leakiness to various constituents of the cell which gradually leads to death of normal lymphocytes. However in the malignant lymphocytes o ....Adenosine triphosphate (ATP) is an important constituent normally present inside cells. When added to normal lymphocytes (or released by cells lining the vessel wall or in lymph nodes), ATP acts from outside these cells to open a pore as well as activate an enzyme which digests the lipid envelope of the cell. This loss of lipid covering of the cell produces a leakiness to various constituents of the cell which gradually leads to death of normal lymphocytes. However in the malignant lymphocytes of human lymphomas this mechanism of cell death does not operate. The loss of function of this 'death receptor' explains why in the lymphomas there is a progressive accumulation of malignant lymphocytes which give enlargement of lymph nodes and spleen and leads to death of the patient. Knowledge of the defect in this pathway of cell death will enable new strategies to be introduced to control this malignant 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