In vivo monitoring of liver oxidative stress defences by magnetic resonance measurements of glutathione turnover

Lead Research Organisation: Newcastle University
Department Name: Institute for Ageing and Health

Abstract

Liver disease is common, causing over 10,000 deaths in the UK per year. Liver disease often occurs as a gradual decline in liver health, with fatty liver, fibrosis and cirrhosis leading towards liver failure. Part of this decline involves ?oxidative stress?. This stress occurs when the liver is overwhelmed by damaging chemical species caused by drugs, alcohol, viral infection and the effects of having a fatty liver.
We are developing new ways of measuring the degree of oxidative stress in the liver, and of measuring how well the liver copes with this stress. We use MRI scanners to measure the liver?s production of glutathione, which is a natural antioxidant that the liver uses for protection against the chemicals that cause oxidative stress. This allows us to gauge the liver?s defence mechanisms in a non-invasive way, using an MRI scanner instead of taking a liver biopsy sample with a needle.
Our studies will characterise how liver glutathione synthesis rate changes when liver oxidative stress occurs, and demonstrates that these measurements can be made in people in a robust and safe manner. Thus we are developing new methods to monitor the role that oxidative stress plays in progression of liver disease. If successful, these methods may play a role in future liver disease research projects, and we hope to use these techniques to assess the impact of therapeutic strategies such as antioxidant supplementation treatments or diet and lifestyle changes.

Technical Summary

Oxidative stress is central to the development and progression of liver disease. The overproduction of reactive oxygen species, and the inability of cells to defend against such insults, plays a central role in the development of fibrosis, hepatitis and cirrhosis. The main causes of oxidative stress are excess alcohol and viral infection, with iron overload, fatty liver and drugs also playing key roles.

Tissue damage occurs if cellular oxidative stress defences are overwhelmed. Glutathione (a tripeptide of cysteine, glycine and glutamate) serves as an antioxidant synthesised by cells, forming a central component of oxidative stress defence. Glutathione turnover reflects the strength of these defences, and is highly responsive to oxidative stress insults. We have developed non-invasive methods to measure glutathione turnover with magnetic resonance techniques. We propose to characterise the changes in liver glutathione synthesis and concentration in response to chronic and acute oxidative stress insults in animal models of liver disease, demonstrating the utility of glutathione turnover rate measurements as a gauge of tissue oxidative stress. We will also demonstrate that these methods can be translated to studies of human liver.

Our methods measure glutathione turnover by introducing a non-radioactive isotope of carbon (13C) into the glutathione biosynthetic pathway. Studies on rats will compare treatment groups that represent normal, steatotic, acute injury (meditated by CCl4 insult), and combined steatotic/acute injury. Liver glutathione synthesis rate and concentration will be compared between treatment groups by MR spectroscopic imaging after infusion of [2-13C]-glycine. Analogous human studies will measure the rate of glutathione biosynthesis following ingestion of 13C-labelled glycine.

The proposed studies will provide a direct method of assessing liver oxidative stress without the need for invasive biospy sampling. We anticipate that development of these techniques and characterisation of response to insults will lead to studies of the real-time effects of antioxidant treatment, or stressors such as paracetamol and alcohol, on liver oxidative stress.

Publications

10 25 50
 
Title 13C spectroscopy protocol 
Description Developed protocol and hardware for acquisition of 13C magnetic resonance spectra from human liver for non-invasive assessment of hepatic lipid content and composition. 
Type Of Material Physiological assessment or outcome measure 
Provided To Others? No  
Impact Used to test determine liver lipid composition in patients with cholesterol ester storage disease. 
 
Title Hepatic lipid composition analysis method 
Description Method to quantify hepatic cholesterol ester content by non-invasive 1H magnetic resonance spectroscopy in patients with cholesterol ester storage disease. Enables progression and treatment monitoring in this patient group using a repeatable, safe and non-invasive scan, instead of requiring liver biopsy. 
Type Of Material Physiological assessment or outcome measure 
Year Produced 2013 
Provided To Others? Yes  
Impact Data analysis method to be employed in a clinical trial of a new enzyme replacement therapy treatment for cholesterol ester storage disease. 
 
Description Edinburgh University - 13C MR spectroscopy 
Organisation University of Edinburgh
Country United Kingdom 
Sector Academic/University 
PI Contribution Provided expertise on in vivo 13C MR spectroscopy methodology for a novel Edinburgh University project investigating brown adipose tissue metabolism.
Collaborator Contribution Edinburgh University project on brown adipose tissue metabolism.
Impact Provided MRI protocols and generated pilot MR data for an MRC grant application to be submitted by Edinburgh University.
Start Year 2013
 
Description Mike Gamcsik 
Organisation University of North Carolina at Chapel Hill
Department UNC/NCSU Joint Department of Biomedical Engineering
Country United States 
Sector Academic/University 
PI Contribution Expertise in magnetic resonance spectroscopy
Collaborator Contribution Expertise in oxidative stress defences
Impact Publications: - "Non-invasive Monitoring of L-2-Oxothiazolidine-4-carboxylate Metabolism in the Rat Brain by In vivo 13C Magnetic Resonance Spectroscopy" - "In vivo magnetic resonance studies of glycine and glutathione metabolism in a rat mammary tumor"
 
Description Nottingham University 
Organisation University of Nottingham
Country United Kingdom 
Sector Academic/University 
PI Contribution Formed a collaborative project to develop measurement of glutathione turnover as a biomarker of liver oxidative stress defences. We provided input into experimental design of a healthy volunteer study of liver glutathione turnover rate, and provided input into data analysis and interpretation.
Collaborator Contribution Design, performance and analysis of a healthy volunteer study of hepatic glutathione turnover rate.
Impact -
Start Year 2015
 
Description Philips 
Organisation Philips Medical Systems UK Ltd
Country United Kingdom 
Sector Private 
PI Contribution Information on MRI scanner technical requirements for development of successful human 13C spectroscopy methods. Publication outputs describing development and application of human 13C spectroscopy methods.
Collaborator Contribution Provision of tools and technologies for development of human 13C spectroscopy measurements. These contributions include: - access to and ability of modify MRI scanner source code to perform and optimise 13C MR spectroscopy - ability to interface in-house and third party RF coils (MRI scanner sensors) to the MRI scanner
Impact Publications with the following DOIs: 10.1152/ajpendo.00376.2015 10.1042/CS20140681 10.1152/japplphysiol.01023.2015 10.1002/hep.26925
Start Year 2009
 
Description Steve Blackband 
Organisation University of Florida
Department Department of Neuroscience
Country United States 
Sector Academic/University 
PI Contribution Expertise on non-invasive measurements of tissue oxidative stress defences.
Collaborator Contribution Access to and expertise with high field MRI scanners.
Impact Publications: - "Non-invasive Monitoring of L-2-Oxothiazolidine-4-carboxylate Metabolism in the Rat Brain by In vivo 13C Magnetic Resonance Spectroscopy" - "In vivo magnetic resonance studies of glycine and glutathione metabolism in a rat mammary tumor"
 
Description Synageva Biopharma 
Organisation Synageva BioPharma Corp
Country United States 
Sector Private 
PI Contribution Development and application of a novel non-invasive method to measure hepatic lipid composition and content via magnetic resonance spectroscopy.
Collaborator Contribution Provision of preclinical research materials for development of a novel non-invasive method to measure hepatic lipid composition.
Impact 1) Publication: Pubmed ID = 23624251 2) Incorporation of novel MRI techniques as outcome measures in a phase 2 clinical trial.
Start Year 2010
 
Title Human hepatic glutathione synthesis rate measurement 
Description Performed first-in-man non-invasive measurement of hepatic glutathione synthesis rate by MRI methods, and demonstrated in preclinical studies that glutathione synthesis rate is a biomarker of cellular defences against oxidative stress in models of liver disease. Principle source of funding has been MRC grant G0801239. 
Type Diagnostic Tool - Imaging
Current Stage Of Development Initial development
Year Development Stage Completed 2013
Development Status On hold
Impact First demonstration of human feasibility of a novel biomarker for the study of liver disease. In addition, the development process led to creation of related methods to assess hepatic lipid composition in an inherited metabolic disorder, which will be used as an outcome measure in a clinical trial of a novel drug. 
 
Description AASLD conference presentation (2013) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Type Of Presentation Poster Presentation
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact Presentation at the American Association for the Study of Liver Diseases, Washington DC, 1st-5th November 2013.

Presentation details = "Magnetic Resonance Detection of Hepatic Cholesteryl Ester Accumulation for Non-invasive Identification and Treatment Monitoring in Lysosomal Acid Lipase Deficiency. P Thelwall, FE Smith, M Leavitt, W Hu, KG. Hollingsworth, C Thomas, M. Trenell, R Taylor, J Rutkowski, AM. Blamire, AG Quinn"

Discussions with clinical researchers regarding applications of characterising perturbed hepatic lipid metabolism.
Year(s) Of Engagement Activity 2013
URL http://www.aasld.org
 
Description LiverNorth newsletter article (2013) 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Type Of Presentation Paper Presentation
Geographic Reach Local
Primary Audience Participants in your research and patient groups
Results and Impact Article on "Using MRI in research into liver disease" published in the newsletter of "LiverNorth" - a support group for patients with liver disease (newsletter circulation = 2050).

No notable impacts to date.
Year(s) Of Engagement Activity 2013
URL http://www.livernorth.org.uk
 
Description LiverNorth patient group discussion 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Type Of Presentation Keynote/Invited Speaker
Geographic Reach Local
Primary Audience Participants in your research and patient groups
Results and Impact 20 patients with liver disease attended a meeting organised by the patient group "Liver North". A presentation was made on how MRI is used in liver research, and was followed by questions and discussions.

Meeting organisers requested a written article on the use of MRI in research into liver disease for their newsletter, distributed to patients with liver disease in the NorthEast of England (circulation = 2050 copies).
Year(s) Of Engagement Activity 2013
URL http://www.livernorth.org.uk
 
Description Physics in medical research - talks to schoolchildren 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? Yes
Type Of Presentation Workshop Facilitator
Geographic Reach Local
Primary Audience Schools
Results and Impact Discussing the role of physics in biomedical research, and discussing research as a career option. Discussions took place with local A-level students visiting our research centre.

not known
Year(s) Of Engagement Activity 2009,2011,2012
 
Description Work experience for A-level physics students 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact One student attended a 3 day work experience titled "Physics in Medical research: MRI". The experience provided an insight into academic research and the practical application of physics in MRI scanning and medical research.

The work experience placement assisted the student degree course choice, and has decided to pursue a degree in physics.
Year(s) Of Engagement Activity 2011