INFLUENCE OF IRON METABOLISM ON THE REGULATION OF INTRA-HEPATIC INFLAMMATORY RESPONSES
Lead Research Organisation:
King's College London
Department Name: Transplantation Immunology & Mucosal Bio
Abstract
Life-long immunosuppression is commonly regarded as obligatory for solid-organ recipients to avoid the risk of graft loss due to rejection. Chronic immunosuppressive therapy however is associated with side effects (infections, nephrotoxicity, diabetes, hypertension and cancer) that have a negative impact on patient mortality. As a result, there is intense interest in strategies to successfully minimise and/or withdraw immunosuppression while maintaining normal allograft function and histology. The demonstration that not all recipients require perpetual immunosuppression to maintain their graft mainly derives from the small subset of patients who discontinue conventional immunosuppression through non-compliance, out of medical necessity, or within drug withdrawal trials, and yet sustain normal graft function. These patients are considered as "operationally" tolerant. Recent studies indicate that in liver transplantation the prevalence of this phenomenon is greater than previously estimated: 15 to 40% or more depending on recipient age and how remote from transplant. This has resulted in tolerance being recognized as a tangible clinical opportunity in liver transplantation. Our group recently described that liver tissue samples from tolerant recipients are characterized by the differential expression of genes involved in the regulation of iron metabolism. These markers correlated with serum levels of iron status-related parameters such as ferritin and hepcidin, and were very accurate at predicting the outcome of an immunosuppressive withdrawal protocol. These observations suggested for the first time that changes in iron homeostasis, even within normal reference ranges, could be playing a role in the regulation of alloimmune responses and intra-hepatic inflammation.
To investigate if iron homeostasis is truly causatively linked to liver allograft tolerance, we recently completed a series of bedside-to-bench preliminary animal experiments in which mice fed an iron-deficient diet were challenged with a compound that induces lymphocyte-mediated hepatitis. The low iron diet induced marked changes in intra-hepatic gene expression. Furthermore, it substantially improved the severity of hepatitis, and this was associated with suboptimal activation of T lymphocytes. Considering that intra-hepatic activation of alloreactive T lymphocytes is required for the establishment of liver allograft tolerance, these preliminary data provide a plausible explanation to account for the results observed in our clinical trial. Furthermore, these results suggest that iron metabolism could be a fundamental and previously unrecognized mechanism through which the balance between tolerance and immunity is regulated in the liver.
The goal of the current proposal is to explore in detail the mechanisms through which low iron and/or low hepcidin regulate liver inflammation and preclude liver transplantation tolerance. This will be accomplished through the following specific aims: 1) to determine the mechanisms through which iron and/or hepcidin influence the liver inflammatory microenvironment following acute and chronic liver injuries ; 2) to define how iron and/or hepcidin influence lymphocyte migration and activation and the generation of regulatory T cells; 3) to interrogate the mechanisms by which low iron and/or hepcidin hamper the development of liver allograft tolerance in rats.
4) to determine if iron homeostasis directly influences liver regeneration.
Altogether, the project will contribute to elucidate the mechanisms responsible for the development of transplantation tolerance following liver transplantation, and will provide the rationale to conduct future drug withdrawal trials and studies aiming at modulating iron metabolism as a means to regulate liver inflammation. This research could have wider implications, as modulation of intracellular iron could be a fundamental mechanism through which T cell function is regulated.
To investigate if iron homeostasis is truly causatively linked to liver allograft tolerance, we recently completed a series of bedside-to-bench preliminary animal experiments in which mice fed an iron-deficient diet were challenged with a compound that induces lymphocyte-mediated hepatitis. The low iron diet induced marked changes in intra-hepatic gene expression. Furthermore, it substantially improved the severity of hepatitis, and this was associated with suboptimal activation of T lymphocytes. Considering that intra-hepatic activation of alloreactive T lymphocytes is required for the establishment of liver allograft tolerance, these preliminary data provide a plausible explanation to account for the results observed in our clinical trial. Furthermore, these results suggest that iron metabolism could be a fundamental and previously unrecognized mechanism through which the balance between tolerance and immunity is regulated in the liver.
The goal of the current proposal is to explore in detail the mechanisms through which low iron and/or low hepcidin regulate liver inflammation and preclude liver transplantation tolerance. This will be accomplished through the following specific aims: 1) to determine the mechanisms through which iron and/or hepcidin influence the liver inflammatory microenvironment following acute and chronic liver injuries ; 2) to define how iron and/or hepcidin influence lymphocyte migration and activation and the generation of regulatory T cells; 3) to interrogate the mechanisms by which low iron and/or hepcidin hamper the development of liver allograft tolerance in rats.
4) to determine if iron homeostasis directly influences liver regeneration.
Altogether, the project will contribute to elucidate the mechanisms responsible for the development of transplantation tolerance following liver transplantation, and will provide the rationale to conduct future drug withdrawal trials and studies aiming at modulating iron metabolism as a means to regulate liver inflammation. This research could have wider implications, as modulation of intracellular iron could be a fundamental mechanism through which T cell function is regulated.
Technical Summary
A sizeable proportion of liver transplant recipients spontaneously develop a state of immune tolerance that allows them to discontinue all immunosuppression and yet sustain normal graft function. In an attempt to characterize this group of patients we recently completed a large multi-centre drug withdrawal trial. Tolerance was found to be associated with iron metabolism parameters (i.e recipients requiring lifelong immunosuppression displayed lower hepcidin and serum iron levels than tolerant patients). To investigate the potential causal link between iron metabolism, intra-hepatic alloimmune responses, and tolerance, we have performed preliminary experiments in rodent models of immune-mediated liver damage that indicate that decreased iron and/or hepcidin levels markedly interfere with baseline intra-hepatic gene expression, inhibit intra-hepatic T cell function, and could interfere with regulatory T cell generation and/or function. These preliminary results suggest that iron homeostasis plays a previously unrecognised role in regulating the balance between liver inflammation and immune tolerance. The aims of the current proposal are to elucidate the exact cellular and molecular pathways through which iron and/or hepcidin modulate inflammatory liver injury, interfere with lymphocyte function and/or migration, and regulate tolerance. Experiments will be performed in murine models of inflammatory liver damage and in a rat model of orthotopic liver transplantation. The project will contribute to elucidate the mechanisms responsible for the development of transplantation tolerance following liver transplantation and will provide insight into the pathogenesis of liver inflammatory disorders.
Planned Impact
Following liver transplantation, the need to administer chronic immunosuppressive therapy results in significant side effects such as infections, nephrotoxicity, diabetes, hypertension and cancer. These co-morbidities have a negative impact on patient mortality and are in part responsible for the stagnation in long-term recipient outcomes observed over the past two decades in liver transplantation. The achievement of liver allograft tolerance (i.e. successful discontinuation of all
immunosuppressive drugs) would therefore have a major impact on the health and well-being of liver transplant recipients. Recent findings by our group have revealed that tolerant liver recipients exhibit specific transcriptional and blood cell phenotypic biomarkers. Furthermore, these results have shown that the regulation of iron homeostasis is closely associated with the development of liver allograft tolerance. Our preliminary experiments in animal models are consistent with the results of our clinical studies and suggest that modulation or iron and/or hepcidin could be a fundamental and previously unrecognized mechanisms through which liver inflammation and tolerance is regulated.
The aims of the current project are to investigate the mechanisms through which iron metabolism influences intra-hepatic inflammation and tolerance in a series of clinically-relevant experimental animal models. Liver transplant recipients will be the main beneficiaries of our research. Elucidation of the mechanisms responsible
for allograft tolerance in clinical liver transplantation will open the door to therapeutic interventions that may intentionally induce tolerance in those recipients who do not spontaneously develop this state. Altogether this would constitute a major paradigm shift in the way liver transplant patients are medically managed and would provide obvious health benefits in terms of decreased morbidities, increased life expectancy and quality of life of liver transplant recipients.In addition to these health benefits associated with the discontinuation of immunosuppressive therapy, the current proposal would also provide an obvious pharmacoeconomic benefit given the high cost of currently administered immunosuppressive medications (more than £4000 yearly per patient). Beyond liver transplantation, the results of the current proposal are likely to be generalizable to non-transplanted patient populations suffering from inflammatory liver conditions (e.g. steatohepatitis, viral hepatitis, autoimmune liver disease), and could have implications for extra-hepatic inflammatory and autoimmune diseases.
immunosuppressive drugs) would therefore have a major impact on the health and well-being of liver transplant recipients. Recent findings by our group have revealed that tolerant liver recipients exhibit specific transcriptional and blood cell phenotypic biomarkers. Furthermore, these results have shown that the regulation of iron homeostasis is closely associated with the development of liver allograft tolerance. Our preliminary experiments in animal models are consistent with the results of our clinical studies and suggest that modulation or iron and/or hepcidin could be a fundamental and previously unrecognized mechanisms through which liver inflammation and tolerance is regulated.
The aims of the current project are to investigate the mechanisms through which iron metabolism influences intra-hepatic inflammation and tolerance in a series of clinically-relevant experimental animal models. Liver transplant recipients will be the main beneficiaries of our research. Elucidation of the mechanisms responsible
for allograft tolerance in clinical liver transplantation will open the door to therapeutic interventions that may intentionally induce tolerance in those recipients who do not spontaneously develop this state. Altogether this would constitute a major paradigm shift in the way liver transplant patients are medically managed and would provide obvious health benefits in terms of decreased morbidities, increased life expectancy and quality of life of liver transplant recipients.In addition to these health benefits associated with the discontinuation of immunosuppressive therapy, the current proposal would also provide an obvious pharmacoeconomic benefit given the high cost of currently administered immunosuppressive medications (more than £4000 yearly per patient). Beyond liver transplantation, the results of the current proposal are likely to be generalizable to non-transplanted patient populations suffering from inflammatory liver conditions (e.g. steatohepatitis, viral hepatitis, autoimmune liver disease), and could have implications for extra-hepatic inflammatory and autoimmune diseases.
Organisations
- King's College London (Lead Research Organisation)
- Charité - University of Medicine Berlin (Collaboration)
- Swiss Center for Electronics and Microtechnology (Collaboration)
- Immune Tolerance Network (Collaboration)
- Leibniz Institute for Interactive Materials (Collaboration)
- Utrecht University (Collaboration)
Publications
Sanchez-Fueyo A
(2016)
Immune Exhaustion and Transplantation.
in American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons
Taubert R
(2016)
Hepatic Infiltrates in Operational Tolerant Patients After Liver Transplantation Show Enrichment of Regulatory T Cells Before Proinflammatory Genes Are Downregulated.
in American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons
Bonaccorsi-Riani E
(2016)
Molecular Characterization of Acute Cellular Rejection Occurring During Intentional Immunosuppression Withdrawal in Liver Transplantation.
in American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons
Ratnasothy K
(2019)
IL-2 therapy preferentially expands adoptively transferred donor-specific Tregs improving skin allograft survival.
in American journal of transplantation : official journal of the American Society of Transplantation and the American Society of Transplant Surgeons
Mastoridis S
(2016)
Biomarkers and immunopathology of tolerance.
in Current opinion in organ transplantation
Mastoridis S
(2015)
Emergent Transcriptomic Technologies and Their Role in the Discovery of Biomarkers of Liver Transplant Tolerance.
in Frontiers in immunology
Lim TY
(2018)
Low-Dose Interleukin-2 for Refractory Autoimmune Hepatitis.
in Hepatology (Baltimore, Md.)
Adams DH
(2015)
From immunosuppression to tolerance.
in Journal of hepatology
Baron D
(2015)
A common gene signature across multiple studies relate biomarkers and functional regulation in tolerance to renal allograft.
in Kidney international
Dumontet E
(2016)
Peripheral phenotype and gene expression profiles of combined liver-kidney transplant patients.
in Liver international : official journal of the International Association for the Study of the Liver
Sanchez-Fueyo A
(2016)
Strategies for minimizing immunosuppression: State of the Art.
in Liver transplantation : official publication of the American Association for the Study of Liver Diseases and the International Liver Transplantation Society
Safinia N
(2016)
Successful expansion of functional and stable regulatory T cells for immunotherapy in liver transplantation.
in Oncotarget
Bonaccorsi-Riani E
(2015)
Iron Deficiency Impairs Intra-Hepatic Lymphocyte Mediated Immune Response.
in PloS one
Whitehouse G
(2017)
IL-2 therapy restores regulatory T-cell dysfunction induced by calcineurin inhibitors
in Proceedings of the National Academy of Sciences
Description | KHP Challenge Fund |
Amount | £73,882 (GBP) |
Funding ID | R140807 |
Organisation | King’s Health Partners |
Sector | Academic/University |
Country | United Kingdom |
Start | 09/2014 |
End | 09/2015 |
Description | MRC DPFS |
Amount | £1,007,574 (GBP) |
Funding ID | MR/N019334/1 |
Organisation | Medical Research Council (MRC) |
Sector | Public |
Country | United Kingdom |
Start | 06/2017 |
End | 05/2021 |
Description | NIH research award |
Amount | $308,873 (USD) |
Funding ID | 5U01AI100807-03 |
Organisation | National Institutes of Health (NIH) |
Sector | Public |
Country | United States |
Start | 01/2015 |
End | 06/2017 |
Description | National Institute of Health Research Efficacy and Mechanism Evaluation (EME) Programme |
Amount | £1,677,143 (GBP) |
Funding ID | 13/94/55 |
Organisation | National Institute for Health Research |
Sector | Public |
Country | United Kingdom |
Start | 01/2015 |
End | 11/2020 |
Description | Roche Organ Transplantation Research Foundation |
Amount | £200,000 (GBP) |
Funding ID | 560883191 ROTRF |
Organisation | Roche Organ Transplantation Research Foundation (ROTRF) |
Sector | Charity/Non Profit |
Country | Switzerland |
Start | 10/2014 |
End | 09/2016 |
Description | BIO-DRIM FP7 EU Consortium |
Organisation | Charité - University of Medicine Berlin |
Country | Germany |
Sector | Academic/University |
PI Contribution | We are the lead investigators in a multi-national clinical trial of immunosuppression discontinuation in liver transplantation. The trial involves clinical sites in UK, Germany, Belgium and Spain, and is funded in part by the EU FP7 BIO-DRIM Consortium. |
Collaborator Contribution | Support on quality of life and health-economic analyses. Support on biomarker commercialisation strategy. |
Impact | 2 publications: Feng S. et al. Evidence of Chronic Allograft Injury in Liver Biopsies From Long-term Pediatric Recipients of Liver Transplants. Gastroenterology 2018. DOI: 10.1053/j.gastro.2018.08.023. Londoño et al. Molecular profiling of subclinical inflammatory lesions in long-term surviving adult liver transplant recipients. Journal of Hepatology 2018 DOI: 10.1016/j.jhep.2018.04.012 |
Start Year | 2013 |
Description | Immune Tolerance Network |
Organisation | Immune Tolerance Network |
Country | United States |
Sector | Charity/Non Profit |
PI Contribution | Myself and my research team are participating as mechanistic investigators in 3 US multi-centre clinical trials of immunosuppression withdrawal in liver transplantation: iWITH (paediatric liver transplantation), OPTIMAL (adult liver transplantation) and ARTEMIS (cell therapy trial in adult liver transplantation). Our contributions are: 1) scientific input into the design of the experimental plan of the studies; 2) performance of high-throughput gene expression analyses on biological specimens collected as part of the trials; 3) multi-parameter bioinformatic analysis of clinical and molecular data; 4) contribution to dissemination of the results. |
Collaborator Contribution | The Immune Tolerance Network is providing biological specimens and funds to conduct the transcriptional studies, as well as the associated meta-data to perform the multi-parameter analysis. |
Impact | 1 publication: Feng S. et al. Evidence of Chronic Allograft Injury in Liver Biopsies From Long-term Pediatric Recipients of Liver Transplants. Gastroenterology 2018. DOI: 10.1053/j.gastro.2018.08.023 |
Start Year | 2012 |
Description | ORGANTRANS H2020 EU Consortium: 'Organ 3D printing for liver regenerative medicine' |
Organisation | Leibniz Institute for Interactive Materials |
Country | Germany |
Sector | Private |
PI Contribution | My research group's contribution is to define how the inflammatory microenvironment present in the setting of liver failure influences liver organoid viability. |
Collaborator Contribution | The aims of the project are to replace liver transplantation for end-stage liver failure patients through the development of a liver tissue 3D printing platform. The project will cover the entire development cycle from cell source and tissue engineering through the trials allowing for early adoption of its results in clinical practice. Importantly, this research will create novel technologies that can be applied to other organ systems in regenerative medicine. |
Impact | This is a multidisciplinary collaboration with an overall budget of € 6,301,156.25 involving partners in Germany, Netherlands, Czechia, Belgium, and UK with expertise in liver cell biology, organoid generation, liver inflammation, biogengineering and commercial. |
Start Year | 2020 |
Description | ORGANTRANS H2020 EU Consortium: 'Organ 3D printing for liver regenerative medicine' |
Organisation | Swiss Center for Electronics and Microtechnology |
Country | Switzerland |
Sector | Charity/Non Profit |
PI Contribution | My research group's contribution is to define how the inflammatory microenvironment present in the setting of liver failure influences liver organoid viability. |
Collaborator Contribution | The aims of the project are to replace liver transplantation for end-stage liver failure patients through the development of a liver tissue 3D printing platform. The project will cover the entire development cycle from cell source and tissue engineering through the trials allowing for early adoption of its results in clinical practice. Importantly, this research will create novel technologies that can be applied to other organ systems in regenerative medicine. |
Impact | This is a multidisciplinary collaboration with an overall budget of € 6,301,156.25 involving partners in Germany, Netherlands, Czechia, Belgium, and UK with expertise in liver cell biology, organoid generation, liver inflammation, biogengineering and commercial. |
Start Year | 2020 |
Description | ORGANTRANS H2020 EU Consortium: 'Organ 3D printing for liver regenerative medicine' |
Organisation | Utrecht University |
Country | Netherlands |
Sector | Academic/University |
PI Contribution | My research group's contribution is to define how the inflammatory microenvironment present in the setting of liver failure influences liver organoid viability. |
Collaborator Contribution | The aims of the project are to replace liver transplantation for end-stage liver failure patients through the development of a liver tissue 3D printing platform. The project will cover the entire development cycle from cell source and tissue engineering through the trials allowing for early adoption of its results in clinical practice. Importantly, this research will create novel technologies that can be applied to other organ systems in regenerative medicine. |
Impact | This is a multidisciplinary collaboration with an overall budget of € 6,301,156.25 involving partners in Germany, Netherlands, Czechia, Belgium, and UK with expertise in liver cell biology, organoid generation, liver inflammation, biogengineering and commercial. |
Start Year | 2020 |
Title | LIFT Clinical Trial: Liver Immunosuppression Free Trial |
Description | Development of a transcriptional test employing human liver tissue to identify liver transplant recipients who can safely discontinue immunosuppressive medication without undergoing rejection. |
Type | Diagnostic Tool - Non-Imaging |
Current Stage Of Development | Late clinical evaluation |
Year Development Stage Completed | 2016 |
Development Status | Under active development/distribution |
Clinical Trial? | Yes |
Impact | The diagnostic tool is currently being validated in a multi-centre international randomised controlled trial supported by NIHR-EME. |
URL | http://www.isrctn.com/ISRCTN47808000 |
Title | ThRIL Clinical Trial: Phase I/II clinical trial of regulatory T cell immunotherapy in liver transplantation |
Description | Use of ex vivo expanded autologous regulatory T cells to induce transplantation tolerance following liver transplantation. |
Type | Therapeutic Intervention - Cellular and gene therapies |
Current Stage Of Development | Refinement. Clinical |
Year Development Stage Completed | 2014 |
Development Status | Under active development/distribution |
Clinical Trial? | Yes |
Impact | Protocol for ex vivo expansion of regulatory T cells under GMP conditions. |
URL | https://clinicaltrials.gov/show/NCT02166177 |
Company Name | QUELL THERAPEUTICS LIMITED |
Description | Quell is a spin-off whose objective is to develop engineered regulatory T cells to treat transplant rejection, autoimmunity and inflammatory diseases. Quell was founded in March 2019 in partnership with scientists from King's College London, University College London and Hannover Medical School. Quell was founded with initial series A financing, led by Syncona Ltd who committed £34M with a further £1M contributed by UCL Technology Fund. |
Year Established | 2019 |
Impact | Quell currently has 12 FTE scientific posts within an overall staff of 22 people. |
Website | https://quell-tx.com |
Description | 4th International Workshop on Clinical Tolerance |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Scientific talk describing the outcome of our clinical trials in live transplant tolerance |
Year(s) Of Engagement Activity | 2019 |