A novel immuno-diagnostic strategy for invasive fungal infections in solid organ transplant patients.
Lead Research Organisation:
Imperial College London
Department Name: Dept of Medicine
Abstract
The drugs used in patients who have organ transplants stop the immune system rejecting the transplant. However, they also impair the immune system‘s response to infection. A major problem for these patients is they become susceptible to life-threatening invasive fungal infections (IFIs).
My pilot studies in renal transplant patients indicate these infections may be due to deficiency of an immune-system activating chemical called interferon- . Furthermore I found that treating IFIs in transplant patients with interferon- injections may dramatically improve their chance of survival.
I now propose to define the mechanisms by which transplant drugs lead to susceptibility to IFIs in a mouse mouse model of invasive fungal infection where the mouse are treated with the same transplant drugs. This will enable me to understand how these immune deficits occur, and develop new diagnostic assays to be tested in parallel clinical studies in renal transplant patients with IFIs.
These studies will lead to the delivery of novel diagnostic assays to identify patients at risk of these infections and identify those patients with IFIs who can benefit from life saving interferon- therapy. It is further anticipated these diagnostic assays could have wider application to many infectious diseases in the future.
My pilot studies in renal transplant patients indicate these infections may be due to deficiency of an immune-system activating chemical called interferon- . Furthermore I found that treating IFIs in transplant patients with interferon- injections may dramatically improve their chance of survival.
I now propose to define the mechanisms by which transplant drugs lead to susceptibility to IFIs in a mouse mouse model of invasive fungal infection where the mouse are treated with the same transplant drugs. This will enable me to understand how these immune deficits occur, and develop new diagnostic assays to be tested in parallel clinical studies in renal transplant patients with IFIs.
These studies will lead to the delivery of novel diagnostic assays to identify patients at risk of these infections and identify those patients with IFIs who can benefit from life saving interferon- therapy. It is further anticipated these diagnostic assays could have wider application to many infectious diseases in the future.
Technical Summary
Key aims and objectives of the project
1) Define the effects of transplant immuno-suppressant drugs on host immunity in the standard hydrocortisone-suppressed (HC) murine model of invasive aspergillosis (IA).
2) Identify the immune deficits that lead to susceptibility to IA in this model.
3) Develop novel diagnostic assays of susceptibility to invasive fungal infections in this model.
4) Validate these diagnostic assays through synergistic studies in renal transplant patients.
Design and Methodology
1) Define the additive effects of the transplant immuno-suppressants tacrolimus (FK506) and mycophenolate (MMF) on mortality in the HC-based model of invasive aspergillosis. Doses of FK506 and MMF will be increased until mortality increases from 50% to >80%. The model will be defined through histopathologiocal, pharmocokinetic, fungal burden and peripheral blood profiling.
2) Identify the key defects in immunity that increase susceptibility to IA in this model. Macrophage, T lymphocyte, NKT cell and dendritic cell populations, function and fungal responses in lung, liver, spleen and peripheral blood will be characterized by conidial phagocytosis assays, RT-PCR and Luminex cytokine assay, FACS analysis, NKT cell xenogenic target assays, and dendritic cell na?ve T-cell co-culture.
3) Develop peripheral blood mononuclear cell (PBMC) microarray and anti-Aspergillus T-cell Elispot IFN- assays that identify increased susceptibility to IA in FK506/MMF-immuno-suppressed mice. PBMCs from infected mice will be stimulated with Aspergillus antigens or control mitogens. Cytokine responses will be assayed by Agilent whole genome microarrays and correlated with immuno-suppressive drug levels and transcriptional markers of drug toxicity. Parallel anti-Aspergillus T-cell IFN- Elispot assays will be performed on peripheral blood. The Elispot assay will provide a highly sensitive means of quantifying the effects of FK506/MMF on T-cell mediated antifungal immunity.
4) Define the utility of the PBMC RT-PCR and Elispot assays described in Component 3 through a controlled clinical study of 40 renal transplant patients with invasive fungal infections. For the PBMC assays, select markers of susceptibility to invasive fungal infection will be translated into a rapid RT-PCR assay that can also identify patients who will benefit from IFN- therapy.
Scientific and Medical Opportunities
1) Deliver a model in which to define the immuno-pathogenesis of transplant infectious diseases.
2) Identify of the key immunological defects that predispose solid organ transplant patients to IFIs.
3) Deliver peripheral blood assays to identify susceptibility to IFI and guide immuno-therapy.
4) Provide a rational basis for future studies of biopharmaceutical modulators for IFIs.
1) Define the effects of transplant immuno-suppressant drugs on host immunity in the standard hydrocortisone-suppressed (HC) murine model of invasive aspergillosis (IA).
2) Identify the immune deficits that lead to susceptibility to IA in this model.
3) Develop novel diagnostic assays of susceptibility to invasive fungal infections in this model.
4) Validate these diagnostic assays through synergistic studies in renal transplant patients.
Design and Methodology
1) Define the additive effects of the transplant immuno-suppressants tacrolimus (FK506) and mycophenolate (MMF) on mortality in the HC-based model of invasive aspergillosis. Doses of FK506 and MMF will be increased until mortality increases from 50% to >80%. The model will be defined through histopathologiocal, pharmocokinetic, fungal burden and peripheral blood profiling.
2) Identify the key defects in immunity that increase susceptibility to IA in this model. Macrophage, T lymphocyte, NKT cell and dendritic cell populations, function and fungal responses in lung, liver, spleen and peripheral blood will be characterized by conidial phagocytosis assays, RT-PCR and Luminex cytokine assay, FACS analysis, NKT cell xenogenic target assays, and dendritic cell na?ve T-cell co-culture.
3) Develop peripheral blood mononuclear cell (PBMC) microarray and anti-Aspergillus T-cell Elispot IFN- assays that identify increased susceptibility to IA in FK506/MMF-immuno-suppressed mice. PBMCs from infected mice will be stimulated with Aspergillus antigens or control mitogens. Cytokine responses will be assayed by Agilent whole genome microarrays and correlated with immuno-suppressive drug levels and transcriptional markers of drug toxicity. Parallel anti-Aspergillus T-cell IFN- Elispot assays will be performed on peripheral blood. The Elispot assay will provide a highly sensitive means of quantifying the effects of FK506/MMF on T-cell mediated antifungal immunity.
4) Define the utility of the PBMC RT-PCR and Elispot assays described in Component 3 through a controlled clinical study of 40 renal transplant patients with invasive fungal infections. For the PBMC assays, select markers of susceptibility to invasive fungal infection will be translated into a rapid RT-PCR assay that can also identify patients who will benefit from IFN- therapy.
Scientific and Medical Opportunities
1) Deliver a model in which to define the immuno-pathogenesis of transplant infectious diseases.
2) Identify of the key immunological defects that predispose solid organ transplant patients to IFIs.
3) Deliver peripheral blood assays to identify susceptibility to IFI and guide immuno-therapy.
4) Provide a rational basis for future studies of biopharmaceutical modulators for IFIs.
Organisations
People |
ORCID iD |
| Darius Armstrong-James (Principal Investigator / Fellow) |