Understanding Rapid T-cell Clearance By The Liver: A Critical Step Towards Improved Liver Transplantation.
Funder
National Health and Medical Research Council
Funding Amount
$412,134.00
Summary
The liver has paradoxical properties: it is the site of effective immune responses to pathogens, but under some circumstances, it is known to induce harmless immune responses. Poor responses can be beneficial in a transplantation setting because, in the absence of immunosuppressive drugs, liver transplants are more readily accepted than other organ allografts. Not only are liver transplants well accepted, they can induce secondary acceptance of kidney or heart grafts from the same donor that wou ....The liver has paradoxical properties: it is the site of effective immune responses to pathogens, but under some circumstances, it is known to induce harmless immune responses. Poor responses can be beneficial in a transplantation setting because, in the absence of immunosuppressive drugs, liver transplants are more readily accepted than other organ allografts. Not only are liver transplants well accepted, they can induce secondary acceptance of kidney or heart grafts from the same donor that would otherwise be rejected. However, this ability of the liver to induce unresponsiveness may allow some viruses to persist, particularly , Hepatitis B and C. Four in every five patients infected with hepatitis C develop a chronic disease due to the inability of the immune system to clear the virus. Although it is known that white blood cells enter the liver and become unresponsive, little is known about the mechanisms that prevent an effective response. The CIA s work has been at the forefront of liver immunology and transplantation by demonstrating that the architecture and vasculature of the liver, and therefore the type of unique cellular interactions taking place within it, are essential to gain an understanding of its unique immunological properties. Using the CIB s unique protocols for solid-organ transplantation in rodents, we will provide evidence for a new mechanism that occurs at very early stages after antigen encounter in the liver. We propose to unravel this mechanism using well characterised transgenic mouse models and advanced analytical technology. We will determine the role of this mechanism in liver transplantation. Our preliminary data point to a very high chance of success. This project will have important implications for transplantation studies and for the development and treatment of food allergies and chronic hepatitis C and other of immune-mediated liver diseases.Read moreRead less
Role Of Hepatocytes In Inducing Primary CD8+ T Cell Activation And Tolerance
Funder
National Health and Medical Research Council
Funding Amount
$159,662.00
Summary
It is well known that tolerance to liver allografts is more readily achieved than to other organ grafts, even across a major histocompatibility (MHC) barrier. According to some experiments, preferential tolerance to liver grafts may be due to development of chimerism involving the very large number of passenger leukocytes of donor hematopoietic origin present in an organ of this size. However, such a concept does not explain all the available data, particularly those relevant to CD8+ T cells, th ....It is well known that tolerance to liver allografts is more readily achieved than to other organ grafts, even across a major histocompatibility (MHC) barrier. According to some experiments, preferential tolerance to liver grafts may be due to development of chimerism involving the very large number of passenger leukocytes of donor hematopoietic origin present in an organ of this size. However, such a concept does not explain all the available data, particularly those relevant to CD8+ T cells, the primary effectors of graft rejection. Moreover, it does not take into account the fact that the liver possesses a unique fenestrated endothelium which is permeable to naive as well as activated T cells, nor the tolerogenic properties of hepatocytes themselves. Our recent experiments suggest that the liver is a site of primary activation for CD8 T cells and that a normal liver contains a significant number of self-reactive CD8+ T cells. The aim of this project is to determine whether activation of CD8+ T cells by hepatocytes contributes to the striking ability of liver grafts to be accepted and to induce tolerance in the CD8 T cell compartment. This would indicate that the liver plays an important role in peripheral tolerance of CD8+ T cells, providing the basis for novel therapies in transplantation and the treatment of autoimmune diseases. Moreover, this project also aims to generate a unique animal model of chronic liver inflammation in the absence of viral infection. Such a model is needed to study cirrhosis and hepatocarcinoma in the absence of potential oncogenes carried by viruses such as hepatitis B.Read moreRead less
Transgenic Mice : A Unique Model To Reassess Specific T Cell Suppression
Funder
National Health and Medical Research Council
Funding Amount
$272,545.00
Summary
Acceptance of transplanted organs is currently achieved by treating the recipient with immunosuppressive drugs that block T cell responses. However, because these drugs are non-specific, they will block all T cell responses, including those directed to undesirable viral or bacterial infections. So, whilst this strategy is the best available at the moment, it is far from ideal. The best treatment would be to induce specific graft acceptance without immunosuppression. In the 1970 s several studies ....Acceptance of transplanted organs is currently achieved by treating the recipient with immunosuppressive drugs that block T cell responses. However, because these drugs are non-specific, they will block all T cell responses, including those directed to undesirable viral or bacterial infections. So, whilst this strategy is the best available at the moment, it is far from ideal. The best treatment would be to induce specific graft acceptance without immunosuppression. In the 1970 s several studies have described treatment of recipients achieving specific suppression mediated by a subset of T lymphocytes. Although the phenomenon can be observed, no consensus has been reached to explain the mechanisms involved in the different models. One reason was the unability to track a population of suppressive T cells. We have now the technology and more knowledge to reassess these studies and understand how specific suppression can be achieved. Our lab has developed transgenic mice to study these phenomenon. One of our transgenic models mimicks the T cell response following liver transplantation. Acceptance of liver transplants is more readily achieved than to other organ grafts, even across a major histocompatibility (MHC) barrier and without immunosuppressive drugs. Not only are liver transplants well accepted, but they may induce secondary acceptance of kidney or heart grafts from the same donor, which would otherwise be rejected. Although this property has been made use of by surgeons, the amazing capacity of the liver to be accepted and to induce acceptance of other organs is still not understood. Previous studies and our own model suggests that specific suppression is involved. Our model which enable us to track the relevant cells provides therefore a unique tool to understand how specific suppression can be achieved. Understanding these mechanisms would help us to design strategies to induce tolerance to any organ without immunosuppressing the patient.Read moreRead less
Novel Approaches To Pathogenesis, Diagnosis &treatment Of Autoimmune Diseases Based On New Insights Into Thymus-dependen
Funder
National Health and Medical Research Council
Funding Amount
$1,045,422.00
Summary
An individual relies upon their immune system to protect against invasion by hostile organisms. The system usually works well. Invading agents (the 'non-self') are detected and attacked by the immune system's patrolling killer T cells. These normally beneficial cells are called T cells because they were formed and educated in an organ called the thymus, which kick-starts our immune system in childhood, but falls into inactivity by adolescence. Sometimes the education system in the thymus goes wr ....An individual relies upon their immune system to protect against invasion by hostile organisms. The system usually works well. Invading agents (the 'non-self') are detected and attacked by the immune system's patrolling killer T cells. These normally beneficial cells are called T cells because they were formed and educated in an organ called the thymus, which kick-starts our immune system in childhood, but falls into inactivity by adolescence. Sometimes the education system in the thymus goes wrong and it releases T cells that mistakenly attack 'self' instead of 'non-self'. This causes autoimmune diseases, such as type1 diabetes, multiple sclerosis and rheumatoid arthritis. The Euro-Thymaide project aims to determine why and how self-attacking T cells are mistakenly released from the thymus into the body. Usually such errant T cells are detected and destroyed within the thymus, before they have the opportunity to escape and cause autoimmune diseases. The ultimate objective is to learn about the thymus recognition process and help the immune system detect and destroy faulty T cells that patrol the body, thereby preventing the onset of autoimmune diseases.Read moreRead less
An Autoantibody In Type 1 Diabetes That Mediates Autonomic Complications
Funder
National Health and Medical Research Council
Funding Amount
$254,591.00
Summary
Type 1 diabetes is a chronic autoimmune disease characterised by destruction of insulin producing cells in the pancreas. One of the most common and serious complications of type 1 diabetes is disruption of the autoimmune nervous system, and once symptoms appear the 5-year mortalityrate is approximately 50%. Symptoms of autonomic dysfunction can be extensive, and involve the stomach, intestine, bladder, heart and reproductive organs. Currently, the management of autonomic dysfunction remains prim ....Type 1 diabetes is a chronic autoimmune disease characterised by destruction of insulin producing cells in the pancreas. One of the most common and serious complications of type 1 diabetes is disruption of the autoimmune nervous system, and once symptoms appear the 5-year mortalityrate is approximately 50%. Symptoms of autonomic dysfunction can be extensive, and involve the stomach, intestine, bladder, heart and reproductive organs. Currently, the management of autonomic dysfunction remains primative due to our poor understanding of the mechanisms underlaying the disease. Recent work from our group has identified an excitatory autoantibody (an antibody against the self) to calcium channels in patients with type 1 diabetes. The anti-calcium channel autoantibody profoundly disrupts gut and bladder function by interfering with autonomic regulation of smooth muscle within these organs. The anti-calcium channel autoantibody is the first functional autoantibody to be detected in type 1 diabetes, and represents a conceptual advance in our understanding of immune mechanisms in this disease. Using animal models and a panel of novel, functional assays of colon, stomach and bladder we will investigate how the anti-calcium channel autoantibodies contribute to autonomic dysfunction in type 1 diabetes. Understanding the mechanisms by which this autoantibody effects autonomic regulation of organ function will enable the development of new therapeutic strategies for better management of patients.Read moreRead less
Helminth Secreted Proteins – From Anthelmintic Vaccines To Therapies For Autoimmunity
Funder
National Health and Medical Research Council
Funding Amount
$739,893.00
Summary
Human helminths (worms) cause chronic disease in developing countries, yet their disappearance from developed countries has been accompanied by an increase in the prevalence of autoimmune and allergic diseases. My resesarch focuses on the proteins these worms secrete and their use in (1) the development of anthelmintic vaccines, and (2) the development of novel anti-inflammatory molecules to treat autoimmunity, particularly diseases affecting the gut.
The Role Of NKT Cell Subsets In The Regulation Of EAE
Funder
National Health and Medical Research Council
Funding Amount
$455,899.00
Summary
Multiple sclerosis (MS) is the most cause of paralysis amongst young adults. Experimental autoimmune encephalomyelitis (EAE) is an animal model of MS that recapitulates many features of the human disease. NKT cells are a group of T cells, whose actiavtion protects against EAE, in an as yet unidentified manner. These studies will provide critical information on the way in which NKT cells regulate immunity and will enhance development of therapies for MS.
Steroidogenic Factor-1, A Novel Regulator Of Hepatic Stellate Cell Function
Funder
National Health and Medical Research Council
Funding Amount
$589,458.00
Summary
Recently, we have discovered that steroidogenic factor-1, a specialized protein that directs cells to make steroid hormones, is present in cells in the liver called stellate cells. This may play a vital role in how the liver responds to damage and whether the liver will the scar and move on to cirrhosis. Our experiments will determine if this is so and how this system functions. This work will provide a basis for future treatments to improve or prevent cirrhosis in liver disease patients.
Basic Mechanism Of Spontaneous Tolerance Of Liver Allografts In A Rat Model.
Funder
National Health and Medical Research Council
Funding Amount
$374,625.00
Summary
Many thousands of Australians have a failing liver and the only treatment for this is a liver transplant. Liver transplantation is a major life-saving strategy and hundreds of Australians are rescued each year who would otherwise have died. Rejection of the transplant is the major problem affecting these patients. This project investigates an animal model where a transplanted rat liver is not rejected, even though the recipient receives no treatment. Previous studies from our group have shown th ....Many thousands of Australians have a failing liver and the only treatment for this is a liver transplant. Liver transplantation is a major life-saving strategy and hundreds of Australians are rescued each year who would otherwise have died. Rejection of the transplant is the major problem affecting these patients. This project investigates an animal model where a transplanted rat liver is not rejected, even though the recipient receives no treatment. Previous studies from our group have shown that acceptance is due to donor white blood cells transferred with the liver and based on this finding we are developing treatments that can be used in transplant patients. The current application for funding tests another breakthrough that we have recently made, that treatment of the recipient with a substance called interleukin 4 prevents liver acceptance. This finding shows that interleukin 4, which was previously thought to be involved in preventing transplant rejection, is actually involved in stimulating rejection of the liver. It might therefore be possible to prevent rejection by altering the pattern of its expression, for example, by using an antibody to remove it. This application also aims to examine the overall expression of a very large number of genes in liver transplant acceptance compared with rejection. This will use a new technology called gene array analysis to examine expression of at least 5,000 genes to identify those that are increased during liver acceptance. In addition, gene therapy will be used to increase expression of a single gene called IDO that we and others have found to be associated with transplant acceptance. This gene will be expressed in white blood cells of the liver donor after transplantation to promote liver acceptance and prevent rejection. Ultimately it is intended that these findings will be used to prolong the survival of liver transplant patients by revealing new ways to prevent rejection of liver transplants.Read moreRead less
The Generation And Function Of Tissue-specific Regulatory T Cells
Funder
National Health and Medical Research Council
Funding Amount
$488,577.00
Summary
The immune system normally protects against invasion by pathogens such as harmful viruses and bacteria. In autoimmune diseases the same mechanisms that are used to protect us are erroneously targeted to our own tissues. We will discover how regulatory lymphocytes, are able to protect against autoimmune disease. Such regulatory lymphocytes are attractive therapeutic agents to prevent a variety of immune-mediated diseases, including autoimmune diseases, allergy and transplantation rejection.