Approaches To Allogeneic Chimerism For The Induction Of Transplantation Tolerance
Funder
National Health and Medical Research Council
Funding Amount
$212,036.00
Summary
All patients with organ failure who receive a transplant require lifelong immunosuppressive medications to prevent the body from rejecting the foreign tissue. Indefinite immunosuppressive therapy is associated with significant side-effects which include infections and cancers. In addition, long-term loss of the transplants due to slow rejection (chronic rejection) remains high. Achieving a state of immunological tolerance in which transplanted tissue is regarded as self, but reactivity to all ot ....All patients with organ failure who receive a transplant require lifelong immunosuppressive medications to prevent the body from rejecting the foreign tissue. Indefinite immunosuppressive therapy is associated with significant side-effects which include infections and cancers. In addition, long-term loss of the transplants due to slow rejection (chronic rejection) remains high. Achieving a state of immunological tolerance in which transplanted tissue is regarded as self, but reactivity to all other foreign tissues (e.g. harmful viruses, bacteria) remain normal, would solve all these problems. Tolerance would eliminate the need for immunosuppressive medications and prevent rejection of transplanted organs. The production of mixed bone marrow chimerism is a potent method of inducing tolerance. Chimerism is a state in which bone marrow tissue from two genetically different individuals coexists in one person. This can be achieved by bone marrow transplantation from a specific donor, and if chimerism is achieved, the recipient will accept all tissues from the bone marrow donor without the need for ongoing immunosuppressive therapy. This study will attempt to examine the use of different therapeutic reagents (e.g. antibodies alone or antibodies linked to idarubicin, a drug which prevent cells dividing) to develop safe protocols for the production of bone marrow chimerism and tolerance for routine clinical use in humans. The study will also examine different cellular components of the donor bone marrow which may induce tolerance.Read moreRead less
Innovative Stem Cell-based Strategies To Establish Immune Tolerance And Tissue Repair
Funder
National Health and Medical Research Council
Funding Amount
$5,554,618.00
Summary
Diseases such as autoimmune gastritis, multiple sclerosis and diabetes arise because a rogue immune system has turned inwards to attack our organs. The organ destruction follows from recognition by the immune system of specific molecules in these organs. These autoimmune diseases are incurable and controlled mainly by long-term administration of substances that suppress the immune system, often with serious side-effects. A rational approach is to render the rogue immune system harmless by removi ....Diseases such as autoimmune gastritis, multiple sclerosis and diabetes arise because a rogue immune system has turned inwards to attack our organs. The organ destruction follows from recognition by the immune system of specific molecules in these organs. These autoimmune diseases are incurable and controlled mainly by long-term administration of substances that suppress the immune system, often with serious side-effects. A rational approach is to render the rogue immune system harmless by removing the cells that recognize these particular molecules. This can be achieved by a Trojan horse approach in which the molecules are delivered to the immune system such that that the immune cells that recognize them are removed. To deliver these molecules to the immune system we will genetically engineer bone marrow stem cells, or embryonic stem cells that generate these stem cells, because they are precursors of mature immune cells. Rejection of organ transplants arise in a similar way and also require long-term immunosuppression. A similar approach can therefore be taken to promote acceptance of foreign organ grafts. In the aged, we will combine these approaches with rejuvenation of the immune system by blockade of sex steroid production and-or by creation of a new immune organ.Read moreRead less
Strategies To Achieve Kidney Transplant Tolerance In A Clinically-relevant Model
Funder
National Health and Medical Research Council
Funding Amount
$663,490.00
Summary
The acceptance of kidney transplants without immunosuppression (tolerance) would avoid the side effects of these powerful drugs and improve long-term graft survival. Donor brain death causes inflammation in transplanted kidneys which can block tolerance. In this project, we aim to determine whether expression of a naturally-occurring soluble anti-inflammatory molecule in the liver can prevent this inflammation, allowing tolerance to develop.
Induction Of Islet Transplant Tolerance In A Humanised Mouse Model
Funder
National Health and Medical Research Council
Funding Amount
$374,552.00
Summary
The current treatment for type 1 diabetes (T1D) is insulin therapy, but it cannot fully prevent chronic complications. Also intensive insulin use increases the risk of fatal hypoglycemia. An emerging therapy which may overcome or at least reduce these problems is the transplantation of human islet cells. But preventing the immune system from rejecting these cell transplants is still a major challenge. This study will develop new therapeutic strategies to protect these transplants from rejection.
The Role Of T-cell Apoptosis In Transplantation Tolerance
Funder
National Health and Medical Research Council
Funding Amount
$173,380.00
Summary
Organ transplantation is the treatment of choice for patients with end-stage heart, lung, liver or kidney failure and there have been spectacular improvements in the early success of these procedures. However the 10 year graft survival rate has not changed much in the past 15 years. One way of overcoming this problem is to manipulate the immune system so that the transplant is accepted indefinitely. This is called tolerance and it works by giving intense immunosuppression for a short period so t ....Organ transplantation is the treatment of choice for patients with end-stage heart, lung, liver or kidney failure and there have been spectacular improvements in the early success of these procedures. However the 10 year graft survival rate has not changed much in the past 15 years. One way of overcoming this problem is to manipulate the immune system so that the transplant is accepted indefinitely. This is called tolerance and it works by giving intense immunosuppression for a short period so that the transplant is accepted indefinitely without the need for long term immunosuppression. The immune mechanism responsible for this phenomenon is complex and is poorly understood. This project aims to study the early events in the immune system that leads to transplantation tolerance. In particular, factors involved in programmed cell death in white blood cells will be studied. Specially bred mice that have blocks in the cell death mechanisms will used to determine what effects these blocks have on the ability to induce tolerance. Other mice that have been genetically altered to allow their white cells to be tracked will be used to study the fate of these cells. If the mechanisms involved in tolerance induction are better understood, then it will be possible to design specific immunosuppressive drugs that will be used to produce tolerance in transplant patients.Read moreRead less
Major Xenoantigens For Neovascularised Porcine Xenografts: The Role Of PERV And MHC In Rejection And Tolerance
Funder
National Health and Medical Research Council
Funding Amount
$504,750.00
Summary
Cross-species transplants (xenografts) of pig organs which use donor pig blood vessels are rejected by antibody which recognises a special target (xenoantigen) on the pig blood vessels; other pig tissue transplants (cellular transplants) which use recipient (not donor pig) blood vessels, are rejected by white blood cells called CD4 T cells. The pig targets recognised by the xenoreactive CD4 T cells are unknown. We plan to identify the major target(s) involved in cellular xenograft rejection. Thi ....Cross-species transplants (xenografts) of pig organs which use donor pig blood vessels are rejected by antibody which recognises a special target (xenoantigen) on the pig blood vessels; other pig tissue transplants (cellular transplants) which use recipient (not donor pig) blood vessels, are rejected by white blood cells called CD4 T cells. The pig targets recognised by the xenoreactive CD4 T cells are unknown. We plan to identify the major target(s) involved in cellular xenograft rejection. This information can then be used to specifically remove or disable only those CD4 T cells capable of recognising the pig tissue and hence facilitate xenograft survival or tolerance without immunosuppression. In this way, the remainder of the CD4 T cell population and immune system is preserved intact. Recent studies have demonstrated that a pig virus (PERV) can be transmitted from pig tissue xenografts to recipient tissues. Our studies have also suggested that the process of xenograft rejection and the immunological recognition of transplant recipient cells infected with the pig virus, are closely related. We plan to investigate this relationship and ascertain whether the immunological destruction of the pig tissue xenograft is largely due to an immune response generated against the pig virus(es) it carries. As an extension of this concept, we will investigate whether long-term xenograft survival (tolerance) is associated with lack of immune reactivity to the pig virus and hence a continual capacity for pig virus to be transmitted to host tissues. This outcome could result in the development of unwanted disease(s) in transplant patients. To prevent these problems, our studies will determine whether it will be essential for such pig virus to be eliminated from the donor pig tissue before transplantation, e.g. by the development of potent anti-viral agents and-or via the development of pig herds that have been genetically engineered to be pig virus (PERV)-deficient.Read moreRead less
Hormonal Resuscitation And P38 MAP Kinase Inhibition To Enhance Quality Of Cadaveric Donor Organs For Transplantation
Funder
National Health and Medical Research Council
Funding Amount
$469,500.00
Summary
The transplantation of organs such as the heart, lung, liver, kidney and pancreas from brain-dead donors is limited primarily by the shortage of donor organs. It is now recognised that as many as 25% (one in four) potentially usuable donor organs are lost after brain death due to the rapid deterioration that occurs in organs after brain death. There is evidence that this deterioration is due to loss of the normal hormones that are essential to the normal functioning of these organs. In this proj ....The transplantation of organs such as the heart, lung, liver, kidney and pancreas from brain-dead donors is limited primarily by the shortage of donor organs. It is now recognised that as many as 25% (one in four) potentially usuable donor organs are lost after brain death due to the rapid deterioration that occurs in organs after brain death. There is evidence that this deterioration is due to loss of the normal hormones that are essential to the normal functioning of these organs. In this project, we will use a pig model of brain death that we have extablished in our laboratory to examine the effects of hormone replacement on the function of organs that are used for transplantation. We will also test a novel drug aimed at protecting donor organs during the period between removal of the organ and transplantation. If successful, these treatments have the potential to markedly increase the numbers of organ transplants and to improve the outcomes for recipients of these transplants. In the Australian and New Zealand setting, a 25% increase in the number of donor organs would results in approximately 220 more people per year receiving these life-saving operations.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
Improving Transplant Outcomes Through Translational Research
Funder
National Health and Medical Research Council
Funding Amount
$406,585.00
Summary
The aim of my research is to improve transplant outcomes by developing novel, clinically realistic, therapeutic options for patients with end-organ failure and for a specific cohort of patients with type 1 diabetes. The goal is to advance transplantation by developing a strong interactive research environment where initiatives are quickly interchanged between the laboratory and the clinic. These include novel trials in islet transplantation and use of genomics to improve transplant outcomes.
Tolerogenic Dendritic Cells In Common Marmoset Renal Transplantation
Funder
National Health and Medical Research Council
Funding Amount
$162,756.00
Summary
ORGAN TRANSPLANT PATIENTS currently need life-long immune suppressing drugs to prevent rejection, often using 15 medications a day, costing Australia $52M in 2002. These drugs increase risks of infection and cancer. 90% of patients develop some form of cancer over 30 years. They also cause non-specific side effects including high blood pressure, diabetes and osteoporosis. The average lifespan of a kidney transplant is 8-15 years. Major causes of kidney transplant loss are rejection and drug toxi ....ORGAN TRANSPLANT PATIENTS currently need life-long immune suppressing drugs to prevent rejection, often using 15 medications a day, costing Australia $52M in 2002. These drugs increase risks of infection and cancer. 90% of patients develop some form of cancer over 30 years. They also cause non-specific side effects including high blood pressure, diabetes and osteoporosis. The average lifespan of a kidney transplant is 8-15 years. Major causes of kidney transplant loss are rejection and drug toxicity. TRANSPLANTS ARE REJECTED when a recipient's immune system sees the kidney as foreign. Immune suppressing drugs prevent rejection by stopping the reaction to foreign tissues, but this causes increased infection and cancer risk. IMMUNE TOLERANCE means the recipient's immune system sees a transplant not as foreign but as part of itself, no longer reacting to it. If tolerance could be achieved for transplants, patients wouldn't need to use immune suppressing drugs. Costs of immune suppression would be nil. Tolerance is the best long-term solution for patients needing transplants. Tolerance has been achieved in various ways in mice models. DENDRITIC CELLS can be used to induce tolerance as they can silence a recipient's immune system, preventing it from seeing transplant tissues as foreign. We have shown in mice that a single infusion of a certain type of dendritic cells caused prolonged transplant tolerance without needing immune suppression. This project aims to use dendritic cells to induce tolerance in a marmoset model - a required step before allowing this therapy to be done in humans. PRIMATES like MARMOSETS have close genetic identity to humans and are ideal transplant models as their immune systems react much more like humans than other animals. Marmosets are not an endangered species and are smaller, cheaper and easier to care for than other primates. Ultimately, experiments in other species would need repeating in primates before human trials could be done.Read moreRead less