Chromatin Remodelling And Transcriptional Regulation Of CD8 T Cell Effector Gene Expression
Funder
National Health and Medical Research Council
Funding Amount
$531,696.00
Summary
A major role for cytotoxic, or killer, T cells is the recognition and removal of virus infected or tumor cells from a host. Upon recognition of a target host cell, killer T cells deliver a package of proteins, termed granzymes, that mediate the removal of these virus infected and tumor cells. Naive killer T cells need to be activated to start producing these effector molecules. This proposal plans to examine the factors that regulate both induction and maintanence of cell specific expression of ....A major role for cytotoxic, or killer, T cells is the recognition and removal of virus infected or tumor cells from a host. Upon recognition of a target host cell, killer T cells deliver a package of proteins, termed granzymes, that mediate the removal of these virus infected and tumor cells. Naive killer T cells need to be activated to start producing these effector molecules. This proposal plans to examine the factors that regulate both induction and maintanence of cell specific expression of these effector molecules. We plan to identify the molecular events that occur within a cells genome to turn on granzyme gene expression and how these factors influence subsequent killer T cell function. The conclusions from these studies will enable us to determine why some killer T cell responses are not effective and what can be done to improve killer T cell function. This has implications for the development of novel vaccine strategies designed to induce immunity against both viral and tumour challenges.Read moreRead less
Human cytomegalovirus (HCMV) is a classic example of a group of herpes viruses, which is found universally throughout all geographic locations and socioeconomic groups, and infects 50% of adults in developed countries. HCMV infection is important to certain high-risk groups. Major areas of concern are: (1) the risk of infection to unborn baby during pregnancy, (2) the risk of infection to people who work with children, and (3) the risk of infection to immunocompromised persons (e.g. organ transp ....Human cytomegalovirus (HCMV) is a classic example of a group of herpes viruses, which is found universally throughout all geographic locations and socioeconomic groups, and infects 50% of adults in developed countries. HCMV infection is important to certain high-risk groups. Major areas of concern are: (1) the risk of infection to unborn baby during pregnancy, (2) the risk of infection to people who work with children, and (3) the risk of infection to immunocompromised persons (e.g. organ transplant patients and HIV-infected individuals). Epidemiological studies have shown that 80%-90% of developing unborn babies who acquire congenital HCMV infection displays a variable pattern of pathological sequelae within the first few years of life that may include hearing loss, vision impairment and mental retardation. There is an increasing argument that a reduction in HCMV load will have a significant effect on the sequelae associated with congenital HCMV infection. Indeed, vaccination provides the most practical modality of achieving such a reduction in HCMV load. To develop such a vaccine, formulation based on viral antigens that activate both protective cellular and humoral responses needs to be tested to assess its immunogenicity. No such vaccine is presently available for HCMV. In this application we have sought to develop a prophylactic vaccine and to test its efficacy in a immunocompetent transgenic mouse model and as well under conditions of immunosuppression (CD4 T cell deficient). The overall strategy is to use this prophylactic vaccine to stimulate the cellular (CD8+ and CD4+ T cells) and humoral responses against multiple HCMV antigens. This vaccine will be based on the novel chimeric polyepitope technology and exploits a novel replication deficient adenovirus expression system which has recently been approved for human use.Read moreRead less
A T Cell-Specific GR Promoter Determines Responsiveness To Glucocorticoids In Different Immune Compartments
Funder
National Health and Medical Research Council
Funding Amount
$417,500.00
Summary
Synthetic glucocorticoids, such as dexamethasone and prednisolone, are commonly used as potent anti-inflammatory steroid drug during the treatment of major human trauma and cancer. A side-effect of these very high steroid doses is a major down-regulation of the immune system, particularly massive death of important immune cells called T-cells, which can have a major impact on patient recovery and potential mortality. These T cells are particularly sensitive to glucocorticoid-induced cell death a ....Synthetic glucocorticoids, such as dexamethasone and prednisolone, are commonly used as potent anti-inflammatory steroid drug during the treatment of major human trauma and cancer. A side-effect of these very high steroid doses is a major down-regulation of the immune system, particularly massive death of important immune cells called T-cells, which can have a major impact on patient recovery and potential mortality. These T cells are particularly sensitive to glucocorticoid-induced cell death and have very high levels of receptors for these steroids called glucocorticoid receptors (GRs). We have discovered a unique GR gene promoter (designated 1A) that is active in T cells. Very little is known about how this gene promoter is regulated. This promoter may be a useful therapeutic target to block T cell death (caused by steroids) during recovery from injury, infection and cancer. Separation of anti-inflammatory and side-effects such as high T-cell death or blockade of these effects on T cells would have a major impact on patient immune status and recovery, and reduce the incidence of debilitating side-effects. Therapeutic down-regulation of this T cell-specific GR gene promoter could lead to targeted blockade of steroid-induced T cell death and help maintain a strong immune system. This application brings together a unique team of investigators (CIs) that have a strong history of collaboration in this area with recent publications in very high ranking international journals. The CIs bring a multi-disciplined approach combining endocrinology, molecular biology and cellular immunology to determine the underlying mechanisms of steroid actions and their effects on immune function. Both Dr Cole (CIA) and Dr Godfrey (CIB) have excellent track records in this area.Read moreRead less
Structural Basis Of Influenza A Virus-specific CD8+ T Cell Receptor Diversity
Funder
National Health and Medical Research Council
Funding Amount
$469,500.00
Summary
Viral infection results in the activation and proliferation of virus-specific T cells that mediate clearance of virally infected cells. Recognition of virally infected cells is meditated by presentation of peptide fragments complexed to Major histocompatibility complex (MHC) class I glycoproteins. Virus-specific T cells recognise these viral protein fragments via a specific receptor expressed at the T cell surface. This proposal plans to examine the structural factors that determine influenza-sp ....Viral infection results in the activation and proliferation of virus-specific T cells that mediate clearance of virally infected cells. Recognition of virally infected cells is meditated by presentation of peptide fragments complexed to Major histocompatibility complex (MHC) class I glycoproteins. Virus-specific T cells recognise these viral protein fragments via a specific receptor expressed at the T cell surface. This proposal plans to examine the structural factors that determine influenza-specific T cell receptor recognition. From these studies, we plan to determine how these structural factors can influence the diversity of virus-specific T cells that are generated after viral infection. The conclusions from these studies will enable us to determine why some virus-specific T cell responses are not diverse and what are the consequences for virus-specific T cell immunity. This has implications for the development of novel vaccine strategies designed to induce immunity against both viral and tumour challenge.Read moreRead less
Regulation Of TNF And SFK Signalling In Immune Cells By TCPTP
Funder
National Health and Medical Research Council
Funding Amount
$454,023.00
Summary
Tumour necrosis factor (TNF) is a potent proinflammatory cytokine that plays an important role in immunity and inflammation. TNF acts on the cell surface to activate two key cellular communication or signalling pathways: the mitogen-activated protein kinase (MAPK) pathway and the nuclear factor kappaB (NFkappaB) pathway. The relative activation of the two pathways can dictate whether cells live and proliferate or differentiate or otherwise die in response to TNF, and therefore determine the natu ....Tumour necrosis factor (TNF) is a potent proinflammatory cytokine that plays an important role in immunity and inflammation. TNF acts on the cell surface to activate two key cellular communication or signalling pathways: the mitogen-activated protein kinase (MAPK) pathway and the nuclear factor kappaB (NFkappaB) pathway. The relative activation of the two pathways can dictate whether cells live and proliferate or differentiate or otherwise die in response to TNF, and therefore determine the nature of the immune or inflammatory response. The T-cell protein tyrosine phosphatase (TCPTP) is known to be important in the immune system and serves as a negative regulator of inflammation. Our preliminary studies have identified TCPTP as a selective regulator of TNF-induced MAPK but not NFkappaB signaling. TCPTP exerts its effects by inactivating Src family kinases (SFK) which are themselves integral to immune and inflammatory responses. In this proposal we will elucidate the molecular basis for TCPTP function in TNF- signalling and characterise the role of TCPTP in TNF and SFK functions in immune cells, in particular T-cells.Read moreRead less
Molecular Interactions Of The Tetraspanins CD37, TSSC6 And CD151 In T Cells
Funder
National Health and Medical Research Council
Funding Amount
$566,575.00
Summary
The tetraspanins are a new type of protein that are found at the surface of cells. Cells of the immune system, such as white blood cells, display at their surface, up to 20 different tetraspanin proteins. However, the precise contributions of these tetraspanin proteins to immunity is still not clear, nor is it clear exactly how tetraspanin proteins differ from one another and why white blood cells need to display so many different tetraspanins. Using genetic technology we have created mice which ....The tetraspanins are a new type of protein that are found at the surface of cells. Cells of the immune system, such as white blood cells, display at their surface, up to 20 different tetraspanin proteins. However, the precise contributions of these tetraspanin proteins to immunity is still not clear, nor is it clear exactly how tetraspanin proteins differ from one another and why white blood cells need to display so many different tetraspanins. Using genetic technology we have created mice which are unable to express certain individual tetraspanin proteins at their cell surface. Excitingly, the immune systems of these mice are not normal, in particular one type of white blood cell, the T cell responds in an exaggerated manner to stimulation. These results suggest a role for tetraspanins in the control and regulation of the immune system. This project will extend these results and work out the precise molecular mechanism by which the tetraspanins exert this control. In the future, a full understanding of how tetraspanins control T cells may ultimately lead to novel ways of controlling the immune system.Read moreRead less
The Role Of RasGRP4, A Mast Cell Specific Protein In Mast Cell Growth, Differentiation And Activation
Funder
National Health and Medical Research Council
Funding Amount
$580,433.00
Summary
Mast cells are cells found in the body which are strategically located at mucosal sites and skin where they form a very important barrier in the immune defence. Mast cells have been implicated in a range of inflammatory disorders such as asthma and more recently they have been shown to participate in immunity against bacteria, viruses and fungi. Although a lot of work has been performed to analyze how mast cells respond to different stimuli and what factors are important in their activation, the ....Mast cells are cells found in the body which are strategically located at mucosal sites and skin where they form a very important barrier in the immune defence. Mast cells have been implicated in a range of inflammatory disorders such as asthma and more recently they have been shown to participate in immunity against bacteria, viruses and fungi. Although a lot of work has been performed to analyze how mast cells respond to different stimuli and what factors are important in their activation, there is little work available concerning what in the mast cell controls it's ability to become a mast cell and not any other cell. We have identified a specific protein that has been designated RasGRP4 which is restricted to mast cells and has, we believe, an important role to play not only in guiding immature cells to become mast cells but also in controlling some of the important functions of mast cells. Understanding this molecule more extensively will give us a much better understanding of diseases that the mast cell is involved in such as asthma and other inflammatory disorders. In addition it may shed insights into how mast cells are involved in immunity against bacteria and viruses.Read moreRead less
Immunodominance In Vaccinia Virus And Recombinant Vaccinia Vaccines
Funder
National Health and Medical Research Council
Funding Amount
$388,455.00
Summary
When confronted with an invading microbe, the human immune system does not recognise its overall shape. Instead, the microbe is chopped up into tiny fragments, called peptides, and these can be recognised by special cells of the immune system called T cells which orchestrate a response. We have a good understanding of this chopping process and can predict many of these peptides, but this is only part of the story. Not all peptides will be recognized by a T cell. Further, through processes we do ....When confronted with an invading microbe, the human immune system does not recognise its overall shape. Instead, the microbe is chopped up into tiny fragments, called peptides, and these can be recognised by special cells of the immune system called T cells which orchestrate a response. We have a good understanding of this chopping process and can predict many of these peptides, but this is only part of the story. Not all peptides will be recognized by a T cell. Further, through processes we do not understand well, T cells that recognize only a few out of the many peptides will dominate an entire immune response. As a result, immune responses are focused in such a way that they recognize only a tiny portion of an invading microbe. Focusing of immune responses also occurs during immunization with vaccines. Some new, genetically engineered vaccines use a harmless microbe to carry small parts of more dangerous pathogens. The parts chosen will not cause any disease by themselves, so the whole vaccine is safe. Vaccines built in this way are in clinical trials for diseases such as AIDS and malaria, but do not work as well as was hoped. These new vaccines are largely made up of the carrier and the parts of the microbe we wish to immunize against (e.g. a part of the AIDS virus) will be only a small fraction of the whole vaccine. Ideally we would like the immune system to focus on this small part of our choosing, but the few studies done suggest that this is not the case. In this project we will study vaccines that use a carrier called vaccinia virus. We will test to what extent immune responses are focused inappropriately. We will then genetically alter the virus and use new immunisation strategies to try and shift the focus of the immune response so that it targets the right parts of the vaccine. The ultimate aim is to improve vaccines, but in the process we may learn more about how the immune system chooses its targets.Read moreRead less
HIV currently infects ~40 million people world-wide, causing ~3 million deaths in 2003, mainly in the world's poorest countries. A cheap, effective vaccine seems the best means of preventing the spread of the epidemic. The two main approaches to vaccination are either to make antibodies (which bind to and inactivate the virus), or killer T cells (which kill infected cells). Many of these vaccines are now being tested in monkeys. The results of killer T cell vaccination trials have been both enco ....HIV currently infects ~40 million people world-wide, causing ~3 million deaths in 2003, mainly in the world's poorest countries. A cheap, effective vaccine seems the best means of preventing the spread of the epidemic. The two main approaches to vaccination are either to make antibodies (which bind to and inactivate the virus), or killer T cells (which kill infected cells). Many of these vaccines are now being tested in monkeys. The results of killer T cell vaccination trials have been both encouraging and disappointing. The vaccines do not appear able to prevent the monkeys from getting infected with the virus. However, in many cases even though the monkeys become infected with HIV, they do not get the usual disease associated with AIDS, and hence live with rather than die from this infection. The aims of this project are to use statistical analysis, and more complex mathematical and computer models to try to analyse the data generated by these vaccine trials and to understand how these partially effective vaccines help control virus. For example, even if a vaccine does not prevent infection, we can investigate whether it slowed viral growth, or increased killing of infected cells, and if so, whether an increase in this response could be effective. In preliminary work we have analysed data from a vaccination trial performed in Boston. The results of this study suggest that the reason vaccinated monkeys still become infected is that the killer T cells produced by the vaccine do not appear to activate for the first 10 days of infection. In these first 10 days the virus grows normally and is able to establish a foothold for continuing infection. By contrast, we find that antibodies act extremely early after infection. The methods we propose have not been used before to study vaccines, and by studying the kinetics of the virus and immune response from a large number of vaccine trials we hope to help identify the optimal vaccine design.Read moreRead less
The establishment of an immune system that is able to distinguish between self and non-self is of fundamental importance for good health and survival. How this specificity is achieved has been an area of intense investigation for many years because a breakdown of this process leads to the development of autoimmune diseases, such as diabetes, or an inability to fight pathogenic organisms. It has been known for many years that the development T cells, a subset of cells involved in mounting immune ....The establishment of an immune system that is able to distinguish between self and non-self is of fundamental importance for good health and survival. How this specificity is achieved has been an area of intense investigation for many years because a breakdown of this process leads to the development of autoimmune diseases, such as diabetes, or an inability to fight pathogenic organisms. It has been known for many years that the development T cells, a subset of cells involved in mounting immune responses, occurs in the thymus. The thymus produces large numbers of immature T cells (called thymocytes) from which a small number receive the appropriate signals to survive and develop into mature T cells. These tailor-made T cells can then enter the blood and peripheral lymphoid organs where they fight infectious organisms without reacting against host (i.e. self) tissues. The work for this project is aimed at determining how proteins inside thymocytes transmit signals that determine whether thymocytes either survive, and develop into T cells, or are eliminated because they react too strongly with self proteins. We have established that a protein called c-Cbl is central to this process as it regulates the initial strength of the signal that determines the fate of thymocytes. Our aim is to identify the putative key protein regulated by c-Cbl that can sense when a signal is too strong following the binding of a thymocyte to a self protein and directs a cell death signalling response. From this critical point of signal splitting we also aim to identify proteins that relay the death signal to the nucleus where they trigger the production of well-characterised proteins required to mediate cell death. By identifying the proteins in this signalling pathway we will have a greater capacity to control the magnitude of immune responses and therefore be able to lessen tissue damage caused by autoimmune reactions.Read moreRead less