Our laboratory is interested in the molecular events that lead to an immune response. We apply advanced techniques in structural and analytical biochemistry, proteomics, cellular immunology, molecular biology and molecular immunology to understanding both the effective and ineffective immunity towards viruses and cancers.
The following areas are under active investigation:
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| Immunoproteomics: Identification by mass spectrometry of MHC-bound peptides isolated from antigen presenting cells during health and disease. Peptides are isolated from the surface of cells, analysed by several modes of mass spectroscopy and sequenced by MS/MS |
Role of post-translational modification of antigens in immunity
We are interested in:
- how the immune system perceives modified antigens; and
- whether aberrant modification or accumulation of modified antigens occurs contribute to the pathology of autoimmune diseases, cancers and viral infections.
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Peptidomics: analysis of antigenic peptides and their role in health and disease
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The adaptive immune system has evolved to recognise peptide fragments of antigens. Depending upon interactions with the receptors on immune effector cells and antigen presenting cells, an immune response will be elicited or the cells will simply be ignored. We are interested in understanding the change in peptide repertoire in response to viral infection, malignant transformation and cellular stress. This type of study has been coined immunoproteomics.
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T cell receptor immunodominance in anti-viral immunity
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After viral infection, antigen-specific CD8+ T cells recognise a complex of small peptide determinants bound to the Major Histocompatibility Complex (MHC) class I glycoprotein on the cell surface. In many cases, these viral peptide antigens induce T cell responses that are biased towards the use of particular T cell receptors (TcRs). The factors that determine TcR bias and diversity of the T cell repertoire during the development of anti-viral immunity are currently not fully understood.
The study of these factors may improve strategies for vaccine design by providing information on how antigenic peptides influence the diversity and quality of the vaccine-induced CD8 T cell repertoires. |
Current projects
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| Role of post-translational modification of antigens in immunity |
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- Post-translational modification of islet autoantigens in type 1 diabetes:
Type 1 diabetes results from T-cell mediated destruction of the insulin-producing beta-cells of the pancreas. Identification of pathogenic T-cells from humans has proven difficult. Recently we have identified an oxidatively modified insulin epitope recognised by CD4+ T-cells from diabetic and at-risk individuals.
This project will be an extension of this work, incorporating functional studies of T-cells, identification of conditions under which beta-cells accumulate modified antigens and characterization of the post-translationally modified epitopes.
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| Identification of PTM epitopes in type 1 diabetes
Upper panel: A structural model of an insulin epitope containing the disulfide bond targetted by autoreactive CD4+ T cells in people at risk of, or with established, type 1 diabetics
Lower panel: Histology of an infiltrated pancreatic islet of a NOD mouse. We use proteomics to understand the molecular switches that result in pancreatic infiltration and beta-cell destruction in the NOD mouse and in human diabetes |
- Role of post-translationally modified antigen in rheumatoid arthritis (RA):
There is mounting evidence from a wide range of autoimmune diseases that pathogenic T cells recognise post-translationally modified self-antigens. The evidence is perhaps strongest for RA, where antibodies specific for citrulline-containing filagrin, vimentin and fibrin are found in the serum of RA patients and are the most specific indicator of rheumatoid arthritis.
RA is one of the most common systemic autoimmune diseases and is characterised by inflammation of synovial tissues and pannus formation. As with most human autoimmune diseases, several genes contribute to disease susceptibility. Based on a variety of evidence, we hypothesize that pathogenic T cell responses toward citrullinated antigens will occur, in addition to the production of autoantibodies. |
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- Post-translational modification of islet autoantigens in type 1 diabetes:
Type 1 diabetes results from T-cell mediated destruction of the insulin-producing beta-cells of the pancreas. Identification of pathogenic T-cells from humans has proven difficult. Recently we have identified an oxidatively modified insulin epitope recognised by CD4+ T-cells from diabetic and at-risk individuals.
This project will be an extension of this work, incorporating functional studies of T-cells, identification of conditions under which beta-cells accumulate modified antigens and characterization of the post-translationally modified epitopes.
- Role of post-translationally modified antigen in rheumatoid arthritis (RA):
There is mounting evidence from a wide range of autoimmune diseases that pathogenic T cells recognise post-translationally modified self-antigens. The evidence is perhaps strongest for RA, where antibodies specific for citrulline-containing filagrin, vimentin and fibrin are found in the serum of RA patients and are the most specific indicator of rheumatoid arthritis.
RA is one of the most common systemic autoimmune diseases and is characterised by inflammation of synovial tissues and pannus formation. As with most human autoimmune diseases, several genes contribute to disease susceptibility. Based on a variety of evidence, we hypothesize that pathogenic T cell responses toward citrullinated antigens will occur, in addition to the production of autoantibodies.
|  Proteomic analysis of antigen expression in pancreatic islets of NOD mice.
Upper panel: 2D gel electrophoretic separation of a NOD islet protein fraction.
Lower panels: A schematic for quantitative analysis of isotope-coded peptides. Our laboratory is developing new methods for quantitation of MHC-bound peptides from different cells, cells with closely-related MHC allotypes or infected versus uninfected cells and tissues |
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Peptidomics: analysis of antigenic peptides and their role in health and disease
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- Assembly of MHC class I molecules: MHC class I assembly involves a number of intracellular chaperones, this ensures optimal peptide selection and shapes the ensuing immune response towards foreign and self-antigens.
Aims of project:
- To examine influence of polymorphism on MHC class I assembly and peptide repertoire
- To investigate the role of chaperones and peptidases in selecting peptide determinants
- To identify other components of the class I loading pathway using functional proteomics approaches
- Unraveling the evolutionary arm wrestle between viruses and host immunity:
Tumors and viruses use many tricks to prevent their detection by the immune system. Given the importance of cytotoxic T cells in eliminating virally infected cells, it is not surprising that viruses frequently interfere with antigen presentation by class I molecules. In response to these tactics some HLA class I polymorphism seems to be more resistant to viral subversion strategies and their selection in human populations may be based upon this property. This project explores the molecular basis of how HLA class I polymorphisms can render certain HLA molecules more resistant to viral subversion than others.
Aims of the project:
- To examine the antigen presentation of natural class I allotypes in cells expressing viral inhibitors of Ag presentation
- To compare the biochemical interactions of virally-sensitive and virally-resistant class I molecules in the peptide-loading complex
- To correlate viral resistance in HLA polymorphism with structural changes in the HLA class I molecule
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New tools for immune peptide identification and bioinformatics
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| Our laboratory is interested in implementing new quantitative strategies
for the analysis of MCH-bound peptides, and optimizing existing strategies
for studying T cell repertoires. In particular, we plan to mine data sets
for the presence of relevant post-translationally modified peptides, and
sequence any unusual peptides. |  |
| Influenza virus as seen by electron microscopy |
- T cell receptor (TcR) immunodominance in anti-viral immunity:
After viral infection, antigen-specific CD8 T cells recognise a complex of small peptide determinants bound to the MHC class I glycoprotein on the cell surface. In many cases, these viral peptide antigens induce T cell responses that are biased towards the use of particular TcRs. The factors that determine TcR bias and T cell repertoire diversity during the development of anti-viral immunity are not fully understood.
Aims of the project:- To examine influenza-specific TcR/H2-D beta-peptide recognition at a molecular level
- To make single amino acid substitutions in the immunodominant flu epitopes and examine how mutated viral epitopes affect T cell receptor diversity and specific TcR interactions
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