Viral Immune Evasion From The NK Cell Ly49H Activation Receptor
Funder
National Health and Medical Research Council
Funding Amount
$239,250.00
Summary
Infection with human cytomegalovirus (HCMV) remains a significant health problem for individuals whose immune systems are immunocompromised (transplant patients and AIDS patients) or poorly developed (such as the foetus and newborn children). While drugs are available to treat HCMV infection the emergence of viral drug escape mutants means there is a medical necessity to develop new therapies and vaccines against this agent. As a basis for this it is important to develop a better understand the ....Infection with human cytomegalovirus (HCMV) remains a significant health problem for individuals whose immune systems are immunocompromised (transplant patients and AIDS patients) or poorly developed (such as the foetus and newborn children). While drugs are available to treat HCMV infection the emergence of viral drug escape mutants means there is a medical necessity to develop new therapies and vaccines against this agent. As a basis for this it is important to develop a better understand the host-virus relationship to rationally design appropriate treatments. As HCMV is species specific and does not infect experimental animals, the murine cytomegalovirus (MCMV) in mice is widely used as a model for HCMV disease. MCMV infection is controlled by both innate and adaptive arms of the host's immune response. Natural killer (NK) cells constitute an important frontline defence against MCMV and understanding how they are activated is of importance to harnessing them for anti-viral control measures. Recently we have shown that NK cells are activated via the interaction of an NK cell activation receptor (Ly49H) with a MCMV-encoded ligand (m157). However, we have also found that MCMV can rapidly mutate its m157 gene to evade effective NK cell control and that wild populations of MCMV have foms of m157 that don't bind to Ly49H. Other studies suggest that m157 can bind to inhibitory NK cell receptors, such as Ly49I, and inactivate the NK cell response. This study seeks to understand the dynamics of the m157-Ly49H and m157-Ly49I interactions. As HCMV infection is also regulated at early stages by NK cells, an understanding of how CMV can rapidly mutate its m157 gene to avoid interaction with Ly49H-expressing NK cells has important implications for understanding human disease caused by HCMV, in terms of potential viral escape from NK cell surveillance.Read moreRead less
Role Of Plasmacytoid Dendritic Cells And Neutrophils In The Generation Of Antiviral Immunity
Funder
National Health and Medical Research Council
Funding Amount
$469,500.00
Summary
Work described in this application is important in understanding how two very different types of white blood cells, namely neutrophils and plasmacytoid dendritic cells (PDC), contribute to the generation of an effective immune response and control of virus growth. Both these cell types are activated in the earliest phase of the host response and are likely to play crucial roles in determining the nature of the later components of the response. We have recently shown that animals depleted of Gr-1 ....Work described in this application is important in understanding how two very different types of white blood cells, namely neutrophils and plasmacytoid dendritic cells (PDC), contribute to the generation of an effective immune response and control of virus growth. Both these cell types are activated in the earliest phase of the host response and are likely to play crucial roles in determining the nature of the later components of the response. We have recently shown that animals depleted of Gr-1+ cells, with monoclonal antibody (mAb) RB6-8C5, rapidly succumb to a poxvirus infection (mousepox) with 100% mortality. In contrast, mice treated with a control mAb clear the infection very effectively. Host responses essential for recovery from mousepox, including antiviral cytotoxic T lymphocyte (CTL) response and gamma interferon production, are severely diminished in mice treated with the Gr-1+ cell depleting mAb. Since the mAb can potentially deplete both neutrophils and PDC, this raises the important question of whether one or both of these cell types may be involved in the generation of cytokine and cell-mediated immune responses to viral infection. Although PDC and neutrophils themselves are not thought to present antigen to T cells, the elucidation of how they may control the generation of this major arm of the immune response will be novel and has important implications for vaccine design. Virtually nothing is known about how neutrophils or PDC influence viral antigen presentation by antigen presenting cells. Several murine models of viral infection, that in many ways mimic the diseases in humans, will be used to map the sequence of events initiated by PDC and neutrophils and which end in the clearance of virus from the host. Understanding these pathways and identifying the essential mediators and their interactions is critical in elucidating the role of the two cell types in the host response to virus infection.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
Defining The Molecular Effectors And Regulators Of Anti-viral Immune Responses
Funder
National Health and Medical Research Council
Funding Amount
$447,750.00
Summary
In humans, cytomegalovirus infection can cause severe disease and may even be fatal in individuals with immature or compromised immune systems, such as newborns, AIDS patients, transplant recipients and people treated with chemotherapeutic drugs. The majority of healthy individuals however can clear the infection with minimal disease. The ability of cytomegalovirus to cause disease is increased in the absence of effective immune responses which would normally clear the virus before illness occur ....In humans, cytomegalovirus infection can cause severe disease and may even be fatal in individuals with immature or compromised immune systems, such as newborns, AIDS patients, transplant recipients and people treated with chemotherapeutic drugs. The majority of healthy individuals however can clear the infection with minimal disease. The ability of cytomegalovirus to cause disease is increased in the absence of effective immune responses which would normally clear the virus before illness occurs. Understanding the role of specific mediators of anti-viral immune responses is therefore of paramount importance in establishing the guidelines for the design of more effective anti-viral therapies. The mouse model of cytomegalovirus infection provides a unique system to dissect the roles of specific components of the immune response during the course of viral infection. Our previous studies have shown that anti-viral immune responses are complex and involve a multitude of players. The central aim of the work in the current proposal is to establish the precise contribution of specific molecular effectors and regulators of anti-viral immune responses and define their relevance during the different stages of viral infection. Hence, the results of these studies will be relevant to understanding the pathogenesis of cytomegalovirus infection in humans and more importantly will provide critical insights into the rational design of improved antiviral drugs and vaccines. Since the molecules and cells under investigation are also known to play a crucial role in immune responses that control tumour growth and transplant survival, the proposed studies will provide valuable insight towards the development of new therapies for pathologies associated not only with cytomegalovirus infection, but also with the conditions named above.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
IgA Mediated Activation Of FcalphaRI, An Fc Receptor And A Leukocyte Ig-like Receptor.
Funder
National Health and Medical Research Council
Funding Amount
$535,500.00
Summary
Our immune system exists to seek and destroy infections caused by bacteria and viruses (pathogens) that would grow in us. B cells in the immune system make antibody tags which attach to pathogens marking them for elimination. A special type of antibody is IgA. IgA occurs in two forms, the first is found at mucosal sites, these are membranous passages in the body, such as the lung, the gut and the genital tract. These communicate with the outside and are the major route of pathogen entry into the ....Our immune system exists to seek and destroy infections caused by bacteria and viruses (pathogens) that would grow in us. B cells in the immune system make antibody tags which attach to pathogens marking them for elimination. A special type of antibody is IgA. IgA occurs in two forms, the first is found at mucosal sites, these are membranous passages in the body, such as the lung, the gut and the genital tract. These communicate with the outside and are the major route of pathogen entry into the body. Here IgA forms a rather passive, but pathogen specific, sticky barrier to prevent microbial pathogens attaching to these large surfaces. In an everyday analogy this IgA behaves somewhat like fly-paper. This subdued response is appropriate as we are constantly exposed to micro-organisms living in our gut, or breathed into our lungs, and our immune system would make us ill if it aggressively attacked our innocuous microbial neighbours. The second type of IgA is found in the blood where it attaches to pathogens that have breached the body's barriers. These IgA tags are actively sought by white blood cells whose function is to protect the body from infection by recognising and engulfing the tagged pathogens and destroying them with killer molecules, including bleach. The IgA-Fc receptor is the sensor on the surface of white blood cells which seeks the IgA tags as they attach to pathogens. In order to survive in this hostile environment some of our pathogens, such as Staphylococcus, have their own strategies to make themselves invisible to the immune system. These strategies include cutting up the IgA tags or blocking the sensors for IgA. In this project we will study how IgA tags turn on white blood cells to destroy pathogens. We will also be looking at two Staphylococcal proteins which block up the sensor for IgA tags. Finally we are endeavouring to understand how it is the mucosal type IgA does not activate the white cells nearly as much as the IgA from the blood.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
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
The Function Of Histidine-rich Glycoprotein In Inflammation And Cancer
Funder
National Health and Medical Research Council
Funding Amount
$455,670.00
Summary
This research proposal investiagtes the role of a molecule known as histidine-rich glycoprotein (HRG) in the important diseases of cancer and inflammation. Inflammatory diseases can occur when the the normal checks on the immune system breakdown resulting in attacks on the body leading to tissue damage (e.g rheumatoid arthritis) and are significant contributors to morbidity and health costs in Australia. Cancer is the leading cause of death in Australia (28.4% of deaths in 2003). HRG has been im ....This research proposal investiagtes the role of a molecule known as histidine-rich glycoprotein (HRG) in the important diseases of cancer and inflammation. Inflammatory diseases can occur when the the normal checks on the immune system breakdown resulting in attacks on the body leading to tissue damage (e.g rheumatoid arthritis) and are significant contributors to morbidity and health costs in Australia. Cancer is the leading cause of death in Australia (28.4% of deaths in 2003). HRG has been implicated in controlling important aspects of inflammatory and cancer disease progression. Namely, HRG appears to regulate the formation and clearance of substances known as immune complexes - the primary cause of tissue damage in this disease. Furthermore, HRG may also control the process of cell invasion which is crucial for the migration of white blood cells of the immune system (leukocytes) to sites of inflammation to combat infections, and is also an important mechanism by which malignant tumour cells escape from primary tumour sites and spread throughout the circulation to other sites in the body. It is this process that makes cancer such a deadly disease. This study aims to define how HRG contributes to these important processes. This information may allow the development of new therapeutic approaches for the treatment of inflammatory diseases and cancer.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