Loss of insulin-producing beta cells leads to type 1 diabetes and rejection of allogeneic islet transplants. The aim of this program is to discover ways of protecting beta cells from damage. We will do this by investigating whether blocking crucial regulators of cell death can protect mouse and human beta cells from destruction in vitro and in vivo. In doing so, we aim to prevent diabetes in mice and potentially improve the survival of islet grafts after transplantation.
Autoimmunity In Double Transgenic Models Of Self Tolerance
Funder
National Health and Medical Research Council
Funding Amount
$157,660.00
Summary
The immune system protects the body against infection by means of a population of circulating white blood cells called lymphocytes. Each lymphocyte has on its surface its own particular receptor which recognises only one out of the universe of possible substances. Receptors are generated in a semi-random way, using a combination of elements encoded by the genes, and it is possible to generate receptors that react with the body itself, rather than with invading organisms. If the cells bearing the ....The immune system protects the body against infection by means of a population of circulating white blood cells called lymphocytes. Each lymphocyte has on its surface its own particular receptor which recognises only one out of the universe of possible substances. Receptors are generated in a semi-random way, using a combination of elements encoded by the genes, and it is possible to generate receptors that react with the body itself, rather than with invading organisms. If the cells bearing these self-reactive receptors become activated, an autoimmune disease ensues. We are using animal models to study how the body deals with self-reactive cells. We will attempt to activate these cells and thus cause autoimmune disease. The experimental manoeuvres that successfully cause autoimmunity in normal animals will provide clues as to the processes that can cause autoimmune disease.Read moreRead less
CD4 T Cell-mediated Tolerance And Autoimmunity To The Gastric H/K ATPase In Genetically Manipulated Mice
Funder
National Health and Medical Research Council
Funding Amount
$295,780.00
Summary
The immune system is designed to protect us from foreign pathogens such as bacteria and viruses. However, the system is not prefect and sometimes attacks an individual's own tissue (termed autoimmunity). Autoimmunity is not uncommon in the population, including diseases such as diabetes, rheumatoid arthritis and pernicious anaemia, to name a few. To study the details associated with why and how the immune system can turn on the host, we use animal models which mimic the human diseases. The model ....The immune system is designed to protect us from foreign pathogens such as bacteria and viruses. However, the system is not prefect and sometimes attacks an individual's own tissue (termed autoimmunity). Autoimmunity is not uncommon in the population, including diseases such as diabetes, rheumatoid arthritis and pernicious anaemia, to name a few. To study the details associated with why and how the immune system can turn on the host, we use animal models which mimic the human diseases. The model we use is a mouse model for autoimmune gastritis which is an organ-specific autoimmune disorder of the stomach. People with autoimmune gastritis produce a specific autoimmune response directed at the acid secreting cells of the stomach call parietal cells. Parietal cells also produced a substance called intrinsic factor which is needed for the absorption of vitamin B12 from the diet. The lack of vitamin B12 uptake results in abnormal red blood cell formation and anaemia; hence the term pernicious anaemia. One of the unanswered questions associated with the immune system is what regulates the whole system so that it does not induce autoimmunity in everyone. The mechanisms which control or prevent autoimmunity is the subject of much debate. There is good evidence that regulation of the immune system is performed by specific suppression by regulatory cells. Many important question about these cells remain unanswered. For example, it is not known how these cells are generated or how they prevent the autoreactive cells from performing their harmful behaviour. Using our animal model for autoimmune gastritis, we are addressing some of the questions which surround the events which induce and protect us from autoimmunity. By using mice in which most of the lymphocytes in the circulation are of the same specificity (TCR-transgenic), we can follow the fate of those cells and look for cells with different characteristics; such as the ability to supress an immune response.Read moreRead less
Characterisation Of An In-vivo Thrombosis Animal Model Of The Antiphospholipid Syndrome Using Beta 2-GPI KO Mice
Funder
National Health and Medical Research Council
Funding Amount
$467,310.00
Summary
The antiphospholipid syndrome is an autoimmune condition characterised by the presence of thrombosis and recurrent miscarriage. The disorder is characterised by circulating antibodies which bind a protein in the blood known as Beta 2- Glycoprotein I. This protein has been thought to be important in controlling the clotting system in humans and other mammals. However, the experiments that have been designed to look at the function of this protein have looked at its function in the test tube. The ....The antiphospholipid syndrome is an autoimmune condition characterised by the presence of thrombosis and recurrent miscarriage. The disorder is characterised by circulating antibodies which bind a protein in the blood known as Beta 2- Glycoprotein I. This protein has been thought to be important in controlling the clotting system in humans and other mammals. However, the experiments that have been designed to look at the function of this protein have looked at its function in the test tube. The exact role of Beta 2-GPI in the body, has not been determined. A way of looking at the function of this protein in the body would be if you eliminated the protein from an animal such as a mouse. By sophisticated molecular biology techniques we have been able to eliminate the gene for Beta 2-GPI in mice thus deriving mice that do not produce any Beta 2-GPI protein. These mice are called Beta 2-GPI knockout mice and are an ideal animal model to examine the function of Beta 2-GPI. Experiments outlined in this proposal will examine the role of Beta 2-GPI in clotting, atherosclerosis and the effect of production of antibodies to Beta 2-GPI in these animals. In addition, since current treatment of patients that have these antibodies consists of long term, sometimes lifelong, treatment with drugs that thin the blood which have potential side effects, we are investigating a novel treatment approach which is directed at eliminating the antibodies that bind Beta 2-GPI. If one could eliminate the antibody production to Beta 2-GPI by these patients there would not be a need for lifelong treatment with drugs such as heparin which thins the blood and there would thus be a reduction in the problems with these medications. To do this we have obtained a specialised chemically modified portion of Beta 2-GPI that has already been shown to work in preliminary experiments.Read moreRead less
The Role Of Dendritic Cell Subsets In The Decision Between T Cell Tolerance And Immunity
Funder
National Health and Medical Research Council
Funding Amount
$445,009.00
Summary
The immune system protects the body against infection by means of a population of circulating white blood cells called lymphocytes. Each lymphocyte has on its surface its own particular receptor which recognises only one out of the universe of possible substances. Receptors are generated in a semi-random way, using a combination of elements encoded by the genes, and it is possible to generate receptors that react with the body itself, rather than with invading organisms. If the cells bearing the ....The immune system protects the body against infection by means of a population of circulating white blood cells called lymphocytes. Each lymphocyte has on its surface its own particular receptor which recognises only one out of the universe of possible substances. Receptors are generated in a semi-random way, using a combination of elements encoded by the genes, and it is possible to generate receptors that react with the body itself, rather than with invading organisms. If the cells bearing these self-reactive receptors become activated, an autoimmune disease ensues. The question of how lymphocytes can tell the difference between the body itself and foreign organisms is of major interest to immunologists. One of the first ideas was that self-reactive lymphocytes are inactivated by making reactions early in life. Despite the simplicity and intellectual appeal of this idea, it is inconsistent with a large body of experimental evidence. On the basis of number of new experiments, I have proposed an alternative model of self tolerance for one of the subsets of lymphocytes. In this model, the cells that help lymphocytes to recognise particular substances possess the property of distinguishing self from foreign, and pass that information on. The aim of this project is to provide direct experimental evidence in support of the model. Many of our attempts to deal with medical problems related to the immune system have been hampered by our lack of understanding of exactly how immune tolerance is controlled. If my model proves to be correct, it will be possible to manipulate immune responses with far greater effectiveness, providing new treatments for autoimmune disease, allergy, graft rejection and vaccination.Read moreRead less
Building a death-defying islet beta cell Type I diabetes results when the cells that produce insulin (the islet beta cells) are killed by the immune system. The beta cell, like any other cell in the body, can be induced to die by activation of a process that leads to cell suicide. During this process, enzymes dismantle the structure of the cell and the remains are eaten by neighboring cells. In diabetes, the stimulus for beta cell suicide is provided by a number of agents most of which are made ....Building a death-defying islet beta cell Type I diabetes results when the cells that produce insulin (the islet beta cells) are killed by the immune system. The beta cell, like any other cell in the body, can be induced to die by activation of a process that leads to cell suicide. During this process, enzymes dismantle the structure of the cell and the remains are eaten by neighboring cells. In diabetes, the stimulus for beta cell suicide is provided by a number of agents most of which are made by the T cells of the immune system. Our aim is to interfere with this cell suicide process and engineer a beta cell that can resist T cell attack. Because genetically manipulated mice provide the flexibility we need to add and subtract genes from the beta cell we will use them as a model to build a death-defying beta cell. We will investigate three strategies. Firstly, cells will be engineered to express a molecule (CD30 ligand) which recognizes a protein on the surface of the attacking T cells and in so doing, sends a signal to the T cells to stop proliferating. Secondly, we will remove proteins (CD95, TNFRI) from the surface of the beta cell, that attacking T cells use to set in motion the cell suicide process. Thirdly, we will engineer beta cells that express inside themselves, cell death inhibitor proteins (Bcl-2, CrmA, p35) that can prevent the automatic process of cell suicide. It is our hope that studies with death-defying beta cells will find a new way to manipulate islet tissue for transplantation. In patients with diabetes, the beta cells have all been destroyed but the attacking T cells still remain. As a result, transplants of new beta cells are rapidly damaged. Beta cells that can resist ongoing immune attack may survive well enough to reverse the symptoms of diabetes. The success of this research could have an impact on a cure for diabetes.Read moreRead less
Functional Genomic Analysis Of NK And NKT Cell Immune Control Of Autoimmunity
Funder
National Health and Medical Research Council
Funding Amount
$692,040.00
Summary
The major populations of white blood cells responsible for learned immunity to are the B cells, which make antibody against microorganisms like bacteria, and the T cells, which kill virally infected cells and help B cells produce antibody. The T and B cells occasionally attack the body s own tissues, resulting in autoimmune disease. These diseases include type 1 diabetes, lupus, and anaemia, and collectively represent the third commonest cause of morbidity and mortality in humans. The major reas ....The major populations of white blood cells responsible for learned immunity to are the B cells, which make antibody against microorganisms like bacteria, and the T cells, which kill virally infected cells and help B cells produce antibody. The T and B cells occasionally attack the body s own tissues, resulting in autoimmune disease. These diseases include type 1 diabetes, lupus, and anaemia, and collectively represent the third commonest cause of morbidity and mortality in humans. The major reason why autoimmunity occurs is thought to be due to a failure in the mechanisms responsible for controlling such unwanted responses. Two other populations of white blood cells are involved in this regulation, termed NK and NKT cells, each of which release important cell hormones. The current project is designed to test whether defects in NK and NKT cells lead to autoimmune disease. For this purpose a special strain of mice (NOD mice) will be used. The reasons for their selection are: 1) they are highly susceptible to a range of autoimmune diseases including diabetes, lupus and anaemia, and 2) we and others have found that they are deficient in both NK and NKT cells. The proposed experiments are divided into two groups, one designed to characterise the nature of the defects in these cells and the other to identify the genes responsible for them. In this way it should be possible to shed light on the genetic basis of autoimmune diseases in general. The approach to be used involves sophisticated techniques of genetic analysis, which require production of special congenic lines of mice. These mice are like NOD mice but carry in addition to NOD genes genetic regions from a non-autoimmune strain with the potential to correct the defects in NK and NKT cells. In this way, it should be possible to pinpoint the disease susceptibility genes involved in causation of autoimmunity and to work out how they affect NK and NKT cells.Read moreRead less