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Listen to this siteWednesday 24 March 2004
This research project seeks to establish a strategy to identify molecular biomarkers of toxicity to assess early changes following exposure to potential neurotoxicants.
Study Duration : October 2002 to September 2005
Contractor : Imperial College London
Assessment of the risk from dietary chemicals usually involves consideration of data from studies in experimental animals that are then extrapolated to humans. It may also consider epidemiological data gathered from studies of exposed individuals.
Assessment of possible neurotoxicity of chemicals found in food is extremely difficult. Thus the need to develop sensitive, non-invasive biomarkers that could be used to detect effects of exposure to such neurotoxicants much sooner and at lower exposure levels than is currently possible. This project aims to develop biomarkers for assessing early changes occurring on exposure of humans to potential neurotoxicants.
The project focuses on the use of minimally-invasive techniques to identify protein biomarkers released into body fluids.
It uses surface-enhanced laser desorption ionisation time of flight (SELDI-TOF) mass spectrometry to compare protein profiles and more conventional proteomics for protein identification.
The study considers the
in vivo
effects of both centrally (CNS) and peripherally acting neurotoxicants using methylmercury and acrylamide as model compounds whose main targets are the CNS (methyl mercury) or peripheral neurones (acrylamide) respectively. Data from rats treated with methylmercury or acrylamide will be compared with in vitro studies performed using cultured rat neuronal cell lines that have been treated with the same compounds as part of the validation of potential biomarkers. These
in vitro
data will then be compared to data obtained using similarly treated human neuronal cell lines with the aim of establishing validated biomarkers for use with human body fluids. The final goal is to generate antibodies against candidate biomarkers, their immunological characterisation and assay.
This project was initially funded as a two year pilot to ensure that it represented a plausible approach before carrying out further studies. Once the validity of this approach had been established the contract was extended for a further year in order to:
Rats were treated with the two neurotoxicants and a range of body fluids, serum, urine, lung lavage and cerebrospinal fluid were collected and analysed by surface enhanced laser desorption ionisation time of flight (SELDI-TOF) mass spectrometry. This technique is able to quantitate several hundred proteins present in the samples simultaneously. The in vitro study used cultured rat and human nerve cells that were treated with the same chemicals and also then analysed by SELDI-TOF mass spectrometry.
In vivo
study - neurotoxicant-treated and control serum and urine samples could be differentiated on the basis of protein ion levels.
It was also possible to identify differences between the profiles produced by the two neurotoxicants.
In vitro
study - Protein profiles of rat and human neuronal cells were also found to be affected by the neurotoxicants with some changes observed in the in vitro studies appearing to be related to those found
in vivo
.
However, attempts to isolate the proteins involved were hampered by the small quantities of sample available i.e. max 2-3 ml serum. This volume is much less than the contractors had used in another study where they succeeded in purifying candidate biomarkers from approximately 12 ml human serum.
As identification of individual proteins was not achieved the last objective to “develop and then characterise and assay antibodies against candidate biomarkers” was not addressed
This project provided proof of principle that the approach used by the contractor had the potential to provide a non-invasive screen for neurotoxicity. Although it was not possible to identify the actual proteins involved during the course of the project, recent analytical developments should now make such identification possible, suggesting that suitable biomarkers can be identified and developed to test for neurotoxicity.
The final report is available from the Agency’s Information Centre.
To obtain a copy, please contact the Enquiry Desk, Information Services, Food Standards Agency (tel: 020 7276 8181/8182 or email:
infocentre@foodstandards.gsi.gov.uk
)
M. Fang, A.R. Boobis, R.J. Edwards; (2007) Searching for novel biomarkers of centrally and peripherally-acting neurotoxicants, using surface-enhanced laser desorption/ionisation-time-of-flight mass spectrometry (SELDI-TOF MS), Food Chemical Toxicology 45, 2126-2137
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