Epigenetic Regulation Of CD8+ T Cell Function And Memory.
Funder
National Health and Medical Research Council
Funding Amount
$578,171.00
Summary
Upon virus infection, a subset of white blood cells, called killer T cells, are recruited to fight the infection. This proposal aims to examine molecular changes that occur within killer T cells and impart their specific function. We also aim to understand how killer T cells are _programmed� as they establish immunological memory. This proposal will provide insights important for the design and improvement of vaccine strategies to fight pathogens such as influenza, HIV and even tumors.
The Role Of C-Cbl In The Regulation Of T Cell Signalling And Development
Funder
National Health and Medical Research Council
Funding Amount
$527,250.00
Summary
c-Cbl is a member of a multi-adaptor protein family that can interact with many signalling proteins via its different domains. Cbl proteins have been implicated as negative regulators of signalling pathways involving protein tyrosine kinases (PTKs). PTKs are enzymes which add phosphate groups to tyrosine residues on other protein substrates, and the process of tyrosine phosphorylation acts as a potent biochemical switch to turn signalling cascades on and off. Studies of Cbl-deficient (knockout) ....c-Cbl is a member of a multi-adaptor protein family that can interact with many signalling proteins via its different domains. Cbl proteins have been implicated as negative regulators of signalling pathways involving protein tyrosine kinases (PTKs). PTKs are enzymes which add phosphate groups to tyrosine residues on other protein substrates, and the process of tyrosine phosphorylation acts as a potent biochemical switch to turn signalling cascades on and off. Studies of Cbl-deficient (knockout) mice show that Cbl proteins are important in regulating the development of, and signalling by, cells of the immune system called T cells. c-Cbl knockout mice show greatly enhanced PTK-signalling responses and deregulated activity of a PTK called ZAP-70. The mechanism of this is not known, but analysis of a c-Cbl mutant mouse shows that this is not dependent on the tyrosine kinase binding (TKB) domain of c-Cbl. Therefore other functional domains of Cbl must be responsible for the increased signalling response in the c-Cbl knockout mouse. One candidate is the highly conserved RING finger domain which can modify Cbl-associated PTKs by addition of ubiquitin molecules. Ubiquitination of a protein often, but not always, leads to its degradation, and this could be how Cbl controls the strength and duration of signalling in T cells. However there may be other functions of the conserved RING finger yet to be identified. c-Cbl itself is prominently and very rapidly modified by tyrosine phosphorylation on tyrosine 737 by the Fyn PTK following T cell activation, but the role of this modification is not known and could also be essential for c-Cbl s function in T cells. We plan to investigate the roles of the RING finger domain and Fyn-mediated tyrosine phosphorylation in c-Cbl regulation of T cell signalling by analyzing knock-in mice that carry specific mutations disrupting the RING finger or tyrosine 737 in the c-Cbl gene.Read moreRead less
Effector And Memory CD8+ T Cell Responses To Engineered Influenza A Escape Mutants
Funder
National Health and Medical Research Council
Funding Amount
$465,210.00
Summary
T cells are a critical component of the immune system after infection with viruses. In particular, virus-specific CD8+ T cells can clear viral infections by killing virally-infected cells and the release of immunomodulators. These are called effector T cells. After the viral infection is cleared, a small proportion of T cells (around 5 to 10%) survives for many years and constitute a memory pool of virus-specific T cells. Memory T cells provide a rapid and effective protection in case of a repea ....T cells are a critical component of the immune system after infection with viruses. In particular, virus-specific CD8+ T cells can clear viral infections by killing virally-infected cells and the release of immunomodulators. These are called effector T cells. After the viral infection is cleared, a small proportion of T cells (around 5 to 10%) survives for many years and constitute a memory pool of virus-specific T cells. Memory T cells provide a rapid and effective protection in case of a repeated infection with the same virus, and hence result in a less severe disease. However, viruses often mutate their genes to escape such efficient T cell responses. In this study, we will investigate T cell responses after infection with mutated strains of influenza viruses. We will engineer a panel of mutant influenza viruses, which alter the nature and characteristics of T cells. We will analyse how efficient are these T cells and whether they can protect against a normal strain of influenza A. Subsequently, we will characterise quantitative and qualitative aspects of memory T cell pools after infection with mutant influenza viruses. Since a number of viruses such as influenza, HIV and HCV rapidly mutate their genes, our study will not only address the question of T cell responses to mutated influenza viruses, but also will provide an excellent model for investigating protective T cell responses to other viral infections.Read moreRead less
Respiratory Viral Infections As Triggers Of Acute Severe Asthma Exacerbations In Atopics: Mechanistic Studies In An Experimental Model
Funder
National Health and Medical Research Council
Funding Amount
$659,494.00
Summary
An important unresolved issue in asthma research is why almost all the children who present in hospital emergency with very severe asthma attacks are both allergic and virally infected. This project will seek to define how immune responses to viruses and aeroallergens interact to create very severe inflammation in the airways thus precipitating the severest type of asthma attacks. Understanding the underlying mechanisms will hopefully provide new clues towards better treatments.
Antigen Dose And TCR Repertoire In CD8+ T Cell Immunodominance Hierarchies
Funder
National Health and Medical Research Council
Funding Amount
$558,920.00
Summary
The CD8+, or killer , T lymphocytes (white blood cells) are the hit men of immunity, recirculating continually around the body to eliminate other cells that are dangerous because they are cancerous or infected with a virus. A major difficulty is that killer T cells also exert selective pressures that cause viruses and tumours to mutate and thus avoid immune control. This is a particularly serious problem for RNA viruses that readily mutate as they divide. These include the human immunodeficiency ....The CD8+, or killer , T lymphocytes (white blood cells) are the hit men of immunity, recirculating continually around the body to eliminate other cells that are dangerous because they are cancerous or infected with a virus. A major difficulty is that killer T cells also exert selective pressures that cause viruses and tumours to mutate and thus avoid immune control. This is a particularly serious problem for RNA viruses that readily mutate as they divide. These include the human immunodeficiency virus (HIV) that causes AIDS and, while the mutations that are most important with influenza viruses are those that modify viral surface proteins recognized by antibodies, such T cell escape mutants can also be a problem with influenza. The other reason why there is particular interest in promoting CD8+ T cell-mediated immunity to influenza is that the killer T cells are very cross-reactive. We have shown that vaccination approaches that prime mouse CD8+ T cells to resist influenza A viruses circulating currently in humans will also protect against the highly lethal, and dangerous H5N1 bird 'flu. The present flu vaccines only stimulate antibodies, so there is interest in the possibility of a major re-design. The CD8+ T cells recognize tiny elements (peptides) of the virus or tumour bound in the tip of our own transplantation, or class I major histocompatibility complex (MHCI) molecules. These pMHCI complexes are called epitopes. The focus here is on the use of novel genetic engineering strategies to find out how, when the virus mutates to disrupt the major epitopes seen by killer T cells, other minor epitopes can be abnormally emphasized in a way that promotes effective immune control. As we work on this with the relatively simple and safe influenza model we will concurrently develop strategies that may be of value in HIV and tumour immunity. Solving this problem could prove to be a substantial advance in the design of vaccines and immunotherapy approaches.Read moreRead less
Developmental Stages Of In Vivo And In Vitro-generated Dendritic Cell Subsets And Regulation Of T Cell Differentiation.
Funder
National Health and Medical Research Council
Funding Amount
$88,087.00
Summary
Dendritic cells (DC) represent a diverse family of white blood cells that form a sentinel network throughout the body involved in the detection and eradication of pathogens and cancer cells. DC can originate from different precursor cells in the bone marrow. It is therefore possible that different types of DC perform differing functions. For instance, DC not only initiate immune responses but are also able to silence them. However, the ability of DC to instruct and orchestrate the immune respons ....Dendritic cells (DC) represent a diverse family of white blood cells that form a sentinel network throughout the body involved in the detection and eradication of pathogens and cancer cells. DC can originate from different precursor cells in the bone marrow. It is therefore possible that different types of DC perform differing functions. For instance, DC not only initiate immune responses but are also able to silence them. However, the ability of DC to instruct and orchestrate the immune response may not only depend upon their origins but also on where they encounter pathogens or cancer cells and what other signals are associated with this encounter. Due to their specialized capacity to instruct the immune response (e.g. T cells, B cells and NK cells) of impending danger, DC are used experimentally to more efficiently deliver vaccines to the immune response so as to eradicate cancer or infectious disease. However, in order to successfully use DC to deliver vaccines, one must first understand how these cells normally behave in the body and what signals can alter their functional ability to orchestrate immune responses. We can generate DC outside the body from their precursors. We can also isolate DC from the circulation. This project seeks to identify how various physiologic stimuli differentially regulate the functional behaviour of DC subsets and how this then influences the DC's ability to instruct the developing T cell immune response. Furthermore, whether these signals are the same for DC generated outside the body with those isolated from the blood. Of particular interest is whether differing types of DC and differing stages of their maturity will differentially influence the T cell's ability to secrete immune response hormones and to recognize and kill cancer cells. The findings of this study have direct implications of how to best harness DC to effectively deliver vaccines and generate potent immune responses against cancer and infectious disease.Read moreRead less