SZ Tan ST4 Ophthalmology MREH

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1 * SZ Tan ST4 Ophthalmology MREH

*Metabolomics is the study/ quantification of endogenous and exogenous metabolites in biological systems Genes define the potential of what may happen and

2 *Metabolomics is the study/ quantification of endogenous and exogenous metabolites in biological systems Genes define the potential of what may happen and metabolites define what has happened Metabolome: the complete set of all metabolites in a biological sample

3 1. Nuclear magnetic resonance (NMR) spectroscopy 2. Mass spectrometry (MS) - Produces spectra of the masses of the atoms/ molecules comprising a sample of material - Spectra are used to determine the isotopic signature of a sample, masses of particles, chemical structure of molecules - Coupled with chromatographic separation techniques: gas vs liquid chromatography

4 Study of tissue metabolism Study of disease pathogenesis Identifications of biomarkers and risk factors for diseases Drug discovery, side effects and toxicity

5 *Biofluid: serum, plasma, urine, CSF *Solid tissues

6 Young SP, Nessim M, Falciani F, Trevino V, Banerjee SP, Scott RA et al. Metabolomic analysis of human vitreous humor differentiates ocular inflammatory disease. Mol Vis 2009; 15: Santiago AR, Garrido MJ, Cristovao AJ, Duarte JM, Carvalho RA, Ambrosio AF. Evaluation of the impact of diabetes on retinal metabolites by NMR spectroscopy. Curr Eye Res; 35(11): Simó R, Carrasco E, García-Ramírez M, Hernández C. Angiogenic and antiangiogenic factors in proliferative diabetic retinopathy. Curr Diabetes Rev 2006;2: Barba I, Garcia-Ramírez M, Hernández C, et al. Metabolic fingerprints of proliferative diabetic retinopathy: an 1H-NMR-based metabonomic approach using vitreous humor. Invest Ophthalmol Vis Sci 2010;51: Mains J, Tan LE, Zhang T, Young L, Shi R, Wilson C. Species variation in small molecule components of animal vitreous. Invest Ophthalmol Vis Sci 2012.

7 *Is vitreous a reliable surrogate of events taking place in the retina?

8 *To compare and contrast the metabolome of rat cornea, lens, vitreous and retina in physiological state

9 *7 Male, Sprague Dawley rats, aged 7-12 weeks were included *All rats kept in the same room, under standard laboratory and fed with the same diet. *7 eyes used for each tissue type

*Tissue extraction was performed using an in house laboratory protocol *Samples analysed using an Accela Ultra

10 *Enucleation was performed immediately after culling *The different ocular tissues (cornea, lens, vitreous and retina) were carefully dissected under microscopic guidance and snap-frozen before analysis. *Tissue extraction was performed using an in house laboratory protocol *Samples analysed using an Accela Ultra High Performance Liquid Chromatography (UHPLC) system coupled to an electrospray hybrid LTQ-Orbitrap Velos mass spectrometer (UHPLC-MS)

11 * Total no of metabolites detected by LC-MS= 6460

12 (15.4%)

13 Type of tissues Vitreous + cornea + lens + retina Number of unique metabolites % of unique metabolites Cornea + lens + retina Vitreous + lens + retina Vitreous + cornea + retina Vitreous + cornea + lens Vitreous + cornea Vitreous + lens Vitreous + retina Cornea + lens Cornea + retina Lens + retina Vitreous Cornea Lens Retina Total

14 1. Only a small number of metabolites found in the vitreous were unique to the vitreous - dumping ground - Waste products of metabolism from cornea and lens are secreted into the aqueous humour and vitreous directly or move into the vitreous indirectly via diffusion, which may explain the similarities between the metabolites found in these 3 tissues.

15 2. Vitreous and retina do not share many common metabolites - barriers that control entry into the vitreous are: endothelium of retinal vessels, retinal pigmented epithelium - in physiological states, Cunha-Vaz et al 69 demonstrated a uni-directional movement of smaller molecules (fluorescein) from the vitreous to retina when fluorescein is injected into the vitreous, even against a very large concentration gradient. - fluorescein does not pass from retinal blood vessels to the vitreous body when administered intravenously. - This uni-directional transport mechanism in the retina is important to protect the eye from toxic materials by preventing their entry into the eye and by removing products of metabolism from the vitreous, and to prevent RD

16 Mass spectrometry is a useful tool to study metabolite composition of ocular tissues Vitreous sampling as a surrogate of retinal metabolism in physiological states may have limited applications In some pathological states when there is increased permeability of the retinal vessels, vitreous analysis may prove a useful technique for studying retinal diseases.

17 * Mamas M, Dunn WB, Neyses L, Goodacre R. The role of metabolites and metabolomics in clinically applicable biomarkers of disease. Archives of Toxicology 2011;85:5-17. * Ellis DI, Dunn WB, Griffin JL, Allwood JW, Goodacre R. Metabolic fingerprinting as a diagnostic tool. Pharmacogenomics 2007;8: * Dunn WB, Broadhurst DI, Atherton HJ, Goodacre R, Griffin JL. Systems level studies of mammalian metabolomes: the roles of mass spectrometry and nuclear magnetic resonance spectroscopy. Chem Soc Rev 2011;40: * Cunha-Vaz JG, Maurice DM. The active transport of fluorescein by the retinal vessels and the retina. J Physiol 1967;191: * Skuta GL CL, Weiss JS. Fundamentals and Principles of Ophthalmology: American Academy of Ophthalmology;

18 *NIHR *Prof Bishop *Katherine Hollywood *Warwick Dunn *Graham Mullard *Jasmina Cehajic *Tiernan Keenan *Paul Begley

HUMAN EYE MAGNETIC RESONANCE IMAGING RELAXOMETRY IN DIABETIC RETINOPATHY

Romanian Reports in Physics, Vol. 66, No. 4, P. 1029 1037, 2014 MEDICAL PHYSICS HUMAN EYE MAGNETIC RESONANCE IMAGING RELAXOMETRY IN DIABETIC RETINOPATHY L. FANEA 1, S. NICOARA 2, S.V. BODEA 3, S.A. SFRANGEU