Metabolomics/Metabonomics
Metabolomics/metabonomics is the term applied to the quantitative measurement of the
metabolic response of living systems to pathophysiologic stimuli or genetic modification1,
and the approach interfaces with the other ‘omics’ technologies as indicated in the
diagram below (taken from ref 2.):
As the scheme suggests, metabolomics analyses the biological endpoint of a ‘condition’
and this is its key advantage over the other technologies.
We are currently engaged in a number of projects in which NMR spectral data recorded
for biofluids –including blood (plasma, sera, erythrocytes), urine and follicular fluid – are
being analysed using various statistical methods, with the common aim of establishing a
link between components of the metabolome and the condition being studied. A brief
description of some of these projects is provided below.
1.
Nicholson, J. K.; Lindon, J. C.; Holmes, E., Xenobiotica 1999, 29, (11), 1181-1189.
2.
A. Di Leo et al Annals of Oncology 2007;18 (Supplement 12):xii8–xii14.
NMR-Based Metabolomic Studies of Atherosclerosis
Warren Yabsley1, Michael Twigg2, Shervanthi Homer-Vanniasinkam2 and Julie
Fisher1
1
2
School of Chemistry, University of Leeds, Leeds, UK.
Leeds Vascular Institute, Leeds General Infirmary, Great George Street, Leeds, LS1 2EX, UK.
NMR studies are being conducted on plasma collected from a variety of
patients taking part in studies of vascular disease. Atherosclerosis, for which
metabolomic biomarkers will be
sought, is a vascular inflammatory
disease and is the leading cause of
heart
attack
and
stroke3.
Atherosclerotic lesions result from an
excessive,
inflammatoryfibroproliferative response to various
forms of insult to the endothelium and
smooth muscle of the artery wall4, the
initial stages of which can occur in
childhood5.
Fig.1 Formation of advanced atherosclerotic lesion.
Rupture of the fibrous cap leads to thrombosis.3
3. Tang, Yang, et al., Local maximal stress hypothesis and computational plaque vulnerability index for atherosclerotic
plaque assessment. Ann Biomed Eng, 2005. 33(12): 1789.
4. Ross, The pathogenesis of atherosclerosis - a perspective for the 1990s. Nature, 1993. 362(6423): 801.
5. Ross, Mechanisms of disease - Atherosclerosis - An inflammatory disease. New England Journal of Medicine, 1999.
340(2): 115.
NMR-Based Profiling of Ovarian Follicular Fluid and Plasma
Cassey McRae1, Nic Orsi2, Vinay Sharma3 and Julie Fisher1
1
School of Chemistry, University of Leeds, Leeds, UK.
Leeds Institute of Molecular Medicine (LIMM), Leeds, UK.
3
The Assisted Conception Unit at St. James’s Hospital, Leeds, UK.
2
The metabolic profile of women undergoing fertility treatment is being
analysed by applying high resolution NMR-based metabolomics to follicular fluid
and plasma. Female egg cells (oocytes) are produced and grow inside follicles
(Figure 2) in the ovaries before ovulation. Inside the follicle the oocyte is
surrounded by a fluid called follicular fluid (FF), which fills the follicular antrum.
It has been shown that FF contains substances that are essential in
successful follicle growth and oocyte fertilisation2. Therefore metabolomic
profiling of FF from women who
have been successful or
unsuccessful
in
infertility
treatment may give rise to
biomarkers that indicate the
likelihood of success of the
treatment.
Considering
the
emotional, health and financial
commitment involved in fertility
treatment, finding a biomarker
Fig. 2 Ovarian graafian follicle.6
that would predict the chances
of successful fertilisation is
clearly desirable.
6. Kronenberg, H.M., Melmed, S., et al. ‘Williams Textbook of Endocrinology.’ Philadelphia: Saunders/Elsevier, 2008.
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NMR-based metabolomics in the search for a biomarker of acute rejection
in renal transplantation
Hayley Fenton1, Paul Goldsmith2, Niaz Ahmad2, Rajendra Prasad2 and Julie
Fisher1
1
2
School of Chemistry, University of Leeds, Leeds, UK.
Department of Organ Transplantation, St James’s University Hospital, Leeds, UK.
A Nuclear Magnetic Resonance (NMR)-based metabolomic approach is
being used to study erythrocyte extracts taken from renal transplant patients with
the aim of identifying possible biomarkers
of acute rejection. This project is being
conducted in tandem with Paul Goldsmith
who is carrying out similar analysis of the
plasma (see below).
Fig. 3 Kidney transplantation 7
Acute rejection occurs due to transplantation into a genetically dissimilar
host. It is one of the key factors determining long-term graft function and survival
in renal patients, being associated with an increasing risk of graft loss8. It occurs
episodically within the first few months post transplantation and is usually
accompanied by an increase in serum creatinine concentration, which is used by
clinicians as a diagnostic test of renal function. However this test is non-specific
and it is difficult to differentiate acute rejection from delayed graft function
(DGF)9.
For definitive diagnosis a biopsy is
required, which poses risks to both the
patient and graft and can also lead to
delayed detection, allowing the condition
to reach a more advanced state10. Earlier
detection ensures treatment can be
administered before substantial damage
is caused to the graft. A potential
biomarker of acute rejection is sought,
which may provide an earlier, noninvasive method for the diagnosis of acute
rejection.
7. The New York Times. Health: Kidney Transplant. 2009; Available from:
http://www.nytimes.com/slideshow/2007/08/01/health/100087Kidneytransplantseries_5.html.
8. McDonald, S., et al., American Journal of Transplantation, 2007. 7(5): p. 1201-1208.
9. Serkova, N., et al., Kidney International, 2005. 67(3): p. 1142-1151.
10. McLaren, A.J., et al. Annals of Surgery, 2000. 232(1): p. 98-103.
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Metabolomic Identification of Non-invasive Biomarkers for Delayed Graft
function and Acute Rejection in Solid Organ Transplantation Using 1H NMR
Spectroscopy
Paul Goldsmith1, Niaz Ahmad1, K. Rajendra Prasad1 and Julie Fisher2
1
2
Department of Organ Transplantation, St James’s University Hospital, Leeds, UK.
School of Chemistry, University of Leeds, Leeds, UK.
Definitive diagnosis of delayed graft function or acute rejection relies on
invasive biopsy of the transplanted organ. Biopsy is not without its risks and
carries with it morbidity and risk to graft. Less invasive tests currently used in
clinical practice are not 100% sensitive or specific.
Using 1H NMR spectroscopy, we are investigating the metabolic change of
plasma from renal and liver transplant recipients over several timepoints in order
to fully understand the metabolic changes associated with transplantation.
The project aims to define the metabolic profile of patients undergoing
renal or liver transplantation and the changes associated with graft dysfunction or
primary function.
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Metabolomics investigations into the effects of deoxynivalenol in humans
Richard Hopton1, Paul Turner2 and Julie Fisher1
1
School of Chemistry, University of Leeds, Leeds, UK.
Molecular Epidemiology Unit, Centre for Epidemiology and Biostatistics, The LIGHT
laboratories, University of Leeds, Leeds, UK.
2
Mycotoxins, such as deoxynivalenol
H 3C
O
OH
(DON, Figure 4), are produced by fungi and
O
contaminate up to 25% of the worlds food
O
supply – frequent human exposure to DON is
through consumption of everyday common
OH
CH3
OH
wheat based foods like bread and biscuits. The
effects of DON exposure on animals are
Fig. 4 Structure of DON
gastrointestinal in nature; vomiting, feed refusal
and immune modulation. However, whilst most species have a DON detoxifying
capability – thought to be due to gut microflora – humans lack this detoxification
pathway, and DON contaminated cereals has previously been implicated in food
poisoning incidents in China and India.
The focus of this research is to determine biomarkers of exposure of DON
and relate these biomarkers to potential health problems. Analysis of both NMR
and mass spectrometric data of human urine samples has permitted volunteers
to be categorised into high or low DON exposure. Chemometric analysis of NMR
data, using partial least squares discriminant analysis (PLS-DA), has yielded a
biomarker of exposure to DON on a small scale study, and has subsequently
been validated with the inclusion of extra samples; these results are being
prepared for publication. A larger scale study is now being conducted under the
auspices of the Food Standards Agency.
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NMR Studies Towards a Biomarker of Preeclampsia
Elizabeth Turner1, James J. Walker2 and Julie Fisher1
1
2
School of Chemistry, University of Leeds, Leeds, UK.
Leeds Institute of Molecular Medicine (LIMM), Leeds, UK.
Preeclampsia (PE) is a human pregnancy-specific condition, the cause of
which is not yet fully understood, but oxidative stress is thought to be
responsible. As evidence of secreted factors into maternal circulation is
emerging, the analysis of blood samples has the potential to reveal the cause
and progression of this disease. 1H-NMR spectroscopy and chemometrics were
applied to establish the metabolic profile for PE, with the hope of identifying
biomarkers of the condition. This permitted a distinction to be made between
women with a normal pregnancy and those with PE, based on the concentrations
of lipids11 and aromatic amino acids12 in plasma, as well as imidazole-based
markers in erythrocytes.1
20
Whole Spectrum
It has been
hypothesised that the
0
erythrocyte membrane
-10
can be damaged by
HYPOTHYROIDISM
VIT C & E
PE,
by
lipid
-20
peroxidation
and
19
31
protein modification. F and P-Dynamic NMR (DNMR) spectroscopy and
matrix diagonalisation have also been applied to investigate this, by measuring
the rate at which erythrocyte transmembrane exchange processes occur. No
significant differences were observed between PE and healthy pregnant women
in the outward permeability or efflux rate constant of fluorinated glucose
exchange. These NMR studies as a whole have contributed to our understanding
of the pathogenesis of preeclampsia.
10
HIGH BMI
11. Turner E, Brewster JA, Simpson NAB, Walker JJ, Fisher J. Reproductive Sciences, accepted.
12. Turner E, Brewster JA, Simpson NAB, Walker JJ, Fisher J. Hypertension in Pregnancy 2008; 27 (3): 225-235.
13. Turner E, Brewster JA, Simpson NAB, Walker JJ, Fisher J. Hypertension in Pregnancy 2007; 26 (3): 329-342.
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