Collaborative Transplantation Group - Honours projects available in 2010
The supervisor will be able to advise which Discipline will administer an Honours project undertaken in this lab.
Background:
In clinical transplantation, when an organ from one individual is transplanted to another non-identical individual it is almost always rejected due to the recipient's immune response. Rejection is prevented in the clinical setting with immunosuppressive drugs however these also suppress the response to infections and tumours. The transplantation group is investigating the mechanism of rejection and acceptance of transplanted organs in animal models with the intention of improving the treatment of transplant patients.
Animal models show that transplanted organs are sometimes accepted without requiring immunosuppression. We have examined one of the most powerful of these models, where a transplanted rat liver is accepted across a complete histocompatibility barrier without requiring immunosuppression. We have made a number of breakthroughs in characterising the model including the demonstration that tolerance is dependent on donor leucocytes, that it is associated with a paradoxical activation of the recipient's rejection response and that some immunosuppressive drugs break tolerance. These findings have direct relevance for the management of clinical transplant patients.
- Role of antibodies in liver transplant rejection
Supervisor + contact details:
- Dr Alex Bishop
- Dr Alexandra Sharland
In the completely MHC-mismatched strain combination of PVG liver donor to DA strain recipient, the liver is accepted without treatment, despite extensive inflammation that resolves within the first month. In contrast, in the high responder Lewis strain recipient the liver is rejected in approximately 14 days, in association with the deposition of IgG1 antibodies starting from day 7. The aim of this project is to determine the mechanism of activation of B cells in rejection. Currently it is thought that all signals for B cell activation including T cell surface molecules such as CD40L and soluble factors such as the cytokine IL-4 are provided in the recipient draining lymph nodes and spleen however we and others have not been able to detect significant cytokine expression in these tissues. In contrast, there is extensive IL-4 expression in the transplanted liver, suggesting that B cells receive their cytokine signal at this site. The project will involve identifying the pattern of development of IgG1-expressing B cells and graft-reactive IgG1 antibody in rejecting (Lewis) recipients compared to tolerant (DA) recipients. The location of IgG1-expressing B cells will be examined in spleen, graft and bone marrow at different times after transplantation and correlated with the appearance of IgG1 deposition in the graft. Expression of CD40L and IL-4 by T cells and CD40 by B cells will be examined in the transplanted liver and in the recipient draining lymph nodes, spleen and bone marrow. Cells will be separated by specific antibodies and magnetic beads into T cells, B cells and myeloid cells and the expression of these molecules, as well as others involved in T cell ? B cell signalling, will be examined by real-time PCR. The pattern of IL-4 expression obtained by real-time PCR will be compared with the pattern obtained by ELISPOT, which measures production by primed cells. These studies will identify the sequential steps involved in T cell signalling to B cells in a well-defined model that closely reflects clinical transplantation.
To arrange for an appointment to discuss your interests, please contact either Dr Alex Bishop of Dr Alexandra Sharland.
- Role of IL-4 in liver transplant tolerance
Supervisor + contact details:
- Dr Alex Bishop
- Dr Alexandra Sharland
We have recently found that recombinant IL-4 treatment of the liver donor promotes acceptance of the transplanted liver in a high-responder strain recipient that would normally reject it. There are several possible mechanisms that could contribute to IL-4-induced liver transplant acceptance and the project involves identifying which mechanism(s) are operating. One possibility is that mast cells are involved as IL-4 induces IgE-expressing cells in the donor liver that have the apparent distribution of mast cells. These could be inducing acceptance of the liver by an IL-9-dependent mechanism. Another possibility is that IL-4 stimulates increased expression of the immunosuppressive molecule indoleamine dioxygenase. These two pathways will be examined in the recipients of IL-4-treated livers that are accepted compared to untreated livers that reject.
The project will involve examination of transplanted liver tissue by histochemistry and immunohistochemistry to identify mast cells and other infiltrating inflammatory cells. Some studies require the co-localisation of markers using double immunofluorescence and confocal laser microscopy. It will also involve the preparation of RNA and the quantification of cytokine expression using real-time PCR. Some experiments will require the dissociation of livers from IL-4-treated or normal animals followed by purification and analysis of the leucocyte populations.
To arrange for an appointment to discuss your interests, please contact either Dr Alex Bishop of Dr Alexandra Sharland.
