The role of NKT cells in the induction of tolerance to foreign organ transplants
Lead Research Organisation:
University of Oxford
Department Name: Surgical Sciences
Abstract
The most important challenge in transplantation is preventing rejection of transplanted organs. Rejection occurs when the body‘s immune system recognises the transplanted foreign organ and destroys it. Current treatments involve lifelong therapy with inhibitors of the whole immune system, which can lead to cancer or infection, or cause other problems such as bone weakening, diabetes, heart disease and kidney damage. This has led to the search for anti-rejection therapies that are specific to the transplanted organ, rather than the entire immune system. The specific lack of an immune response to the transplant is called tolerance.
It is now clear that disrupting certain molecules that are critical to the immune response to transplants can result in tolerance in experimental models and it has been proposed that a newly described immune cell (called NKT cells) are instrumental to the success of such strategies. However, how NKT cells participate in the induction of tolerance remains unknown. We aim to determine how NKT cells interact with other cells of the immune system during the induction of tolerance. With this knowledge we will investigate ways of manipulating the response of NKT cells, which may then be used to facilitate the induction of tolerance in clinical transplantation.
It is now clear that disrupting certain molecules that are critical to the immune response to transplants can result in tolerance in experimental models and it has been proposed that a newly described immune cell (called NKT cells) are instrumental to the success of such strategies. However, how NKT cells participate in the induction of tolerance remains unknown. We aim to determine how NKT cells interact with other cells of the immune system during the induction of tolerance. With this knowledge we will investigate ways of manipulating the response of NKT cells, which may then be used to facilitate the induction of tolerance in clinical transplantation.
Technical Summary
Natural Killer T (NKT) cells are a critical component in the control of immune responses to pathogens and tumours. However, in a transplant setting, it remains unknown how NKT cell responses participate in tolerance induction strategies. Of particular interest is how NKT cells influence the response of alloantigen reactive T cells, particularly regulatory T cells (Treg), during the induction of tolerance to foreign organ transplants.
AIMS AND OBJECTIVES
1. To study the impact of tolerance induction protocols on NKT responses to alloantigen in mice.
2. To determine the impact of GalCer or alloantigen driven NKT cell responses on tolerance induction to mouse heterotopic cardiac allografts.
3. To evaluate whether concomitant NKT cell responses lead to increased generation and/or functional activity of alloantigen reactive CD25+CD4+ Treg.
4. To assess whether NKT cell responses augment the activity of Treg during active regulation.
DESIGN AND METHODOLOGY
We will compare allograft survival following the administration of tolerance induction protocols (co-receptor/costimulatory molecule blockade and donor cells) in wild-type (WT) recipient mice compared to recipients lacking NKT cells (CD1d-/-) or invariant NKT cells only (V 14-/- mice).
NKT cell responses to alloantigen or Galcer (with and without lenalidomide or co-receptor/costimulatory molecule blockade) will be visualised using flow cytometry to both identify NKT cells and to gauge their response (intracellular cytokine staining). Immune responses to cardiac allografts will be assessed by a combination of flow cytometry of peripheral leukocytes and graft infiltrating cells (GICs) as well as graft immunohistochemistry and real-time RT-PCR.
To assess the potency and visualise the effect of Treg (with and without NKT cells during generation or during active regulation), Treg, NKT and alloreactive TCR-transgenic T cells will be sorted by flow cytometry and co-transferred into immunodeficient RAG-/- mice. Such mice will receive a skin allograft and the impact of NKT cells on the control of rejection by Treg determined. T cell responses to the allograft will be evaluated using flow cytometry, quantitative RT-PCR (for the expression of pro-inflammatory genes) and immunohistochemistry.
SCIENTIFIC AND MEDICAL OPPORTUNITIES
The information resulting from the proposed programme of work will be invaluable in dissecting the contribution of NKT cell responses to the generation and function of alloreactive Treg. Through these studies we envisage that current experimental tolerance induction protocols can be significantly improved by the manipulation of NKT cells during the induction of tolerance which will be crucial to the transition of experimental tolerance induction protocols to clinical transplantation.
AIMS AND OBJECTIVES
1. To study the impact of tolerance induction protocols on NKT responses to alloantigen in mice.
2. To determine the impact of GalCer or alloantigen driven NKT cell responses on tolerance induction to mouse heterotopic cardiac allografts.
3. To evaluate whether concomitant NKT cell responses lead to increased generation and/or functional activity of alloantigen reactive CD25+CD4+ Treg.
4. To assess whether NKT cell responses augment the activity of Treg during active regulation.
DESIGN AND METHODOLOGY
We will compare allograft survival following the administration of tolerance induction protocols (co-receptor/costimulatory molecule blockade and donor cells) in wild-type (WT) recipient mice compared to recipients lacking NKT cells (CD1d-/-) or invariant NKT cells only (V 14-/- mice).
NKT cell responses to alloantigen or Galcer (with and without lenalidomide or co-receptor/costimulatory molecule blockade) will be visualised using flow cytometry to both identify NKT cells and to gauge their response (intracellular cytokine staining). Immune responses to cardiac allografts will be assessed by a combination of flow cytometry of peripheral leukocytes and graft infiltrating cells (GICs) as well as graft immunohistochemistry and real-time RT-PCR.
To assess the potency and visualise the effect of Treg (with and without NKT cells during generation or during active regulation), Treg, NKT and alloreactive TCR-transgenic T cells will be sorted by flow cytometry and co-transferred into immunodeficient RAG-/- mice. Such mice will receive a skin allograft and the impact of NKT cells on the control of rejection by Treg determined. T cell responses to the allograft will be evaluated using flow cytometry, quantitative RT-PCR (for the expression of pro-inflammatory genes) and immunohistochemistry.
SCIENTIFIC AND MEDICAL OPPORTUNITIES
The information resulting from the proposed programme of work will be invaluable in dissecting the contribution of NKT cell responses to the generation and function of alloreactive Treg. Through these studies we envisage that current experimental tolerance induction protocols can be significantly improved by the manipulation of NKT cells during the induction of tolerance which will be crucial to the transition of experimental tolerance induction protocols to clinical transplantation.