Increase of uric acid and purine compounds in biological fluids of multiple sclerosis patients Angela M. Amorini a , Axel Petzold b , Barbara Tavazzi a , Judith Eikelenboom c , Geoffrey Keir b , Antonio Belli d , Gavin Giovannoni e , Valentina Di Pietro a , Chris Polman c , Serafina D'Urso f , Roberto Vagnozzi g , Bernard Uitdehaag c , Giuseppe Lazzarino f, ⁎ a Institute of Biochemistry and Clinical Biochemistry, Catholic University of Rome “Sacro Cuore”, Rome, Italy b Department of Neuroinflammation, Neuroimmunology and CSF Unit, Institute of Neurology, UCL, London, United Kingdom c Department of Neurology, VU Medical Centre, University of Amsterdam, Amsterdam, The Netherlands d Division of Clinical Neurosciences, University of Southampton, Southampton, United Kingdom e Department of Neurology, The Royal London Hospital, London, United Kingdom f Department of Chemical Sciences, Laboratory of Biochemistry, University of Catania, Viale A. Doria 6, 95125 Catania, Italy g Department of Neurosciences, University of Rome “Tor Vergata”, Rome, Italy Received 13 February 2009; received in revised form 12 March 2009; accepted 19 March 2009 Available online 31 March 2009 Abstract Objectives: In this study, the concentrations of uric acid, purine profile and creatinine in samples of cerebrospinal fluid and serum of multiple sclerosis (MS) patients were measured by HPLC and compared with corresponding values recorded in patients without MS (cerebrospinal fluid) and healthy subjects (serum). Design and methods: All samples were deproteinized with ultrafiltration (which ensures minimal sample manipulation and efficient protein removal) and then assayed for the synchronous HPLC separation of uric acid, hypoxanthine, xanthine, inosine, adenosine, guanosine and creatinine. Results: The values of all compounds assayed were significantly higher in both biological fluids of MS patients with respect to values measured in controls. In particular, serum hypoxanthine, xanthine, uric acid and sum of oxypurines were, respectively, 3.17, 3.11, 1.23 and 1.27-fold higher in these patients than corresponding values recorded in controls (p b 0.001). Conclusions: Differently from what previously reported, we here demonstrate that all purine compounds, including uric acid, are elevated in biological fluids of MS patients. Reinforced by the trend observed for creatinine, this corroborates the notion of sustained purine catabolism, possibly due to imbalance in ATP homeostasis, under these pathological conditions. These results cast doubt on the hypothesis that uric acid is depleted in MS because of increased oxidative stress, rather suggesting that this disease causes a generalized increase in purine catabolism. As observed in other pathological states, uric acid, purine compounds and creatinine, can be considered markers of metabolic energy imbalance rather than of reactive oxygen species, even in MS. © 2009 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved. Keywords: Multiple sclerosis; Uric acid; Purine compounds; Cerebrospinal fluid; Serum; HPLC; Energy metabolism; Oxidative stress; Nitrosative stress Introduction The neurodegenerative demyelinating disorder known as multiple sclerosis (MS) affects the central nervous system through autoimmune pathogenetic mechanisms. Several studies have postulated that reactive oxygen species (ROS) and reactive nitrogen species (RNS) might play a key role in the disease development by contributing to myelin and oligodendroglia degeneration, characteristics of MS [1,2]. ROS and RNS production is physiologically buffered by several enzymatic (superoxide dismutase, catalase, glutathione peroxidase, etc.) and non-enzymatic (glutathione, ascorbic acid, α-tochopherol, coenzyme Q 10 , uric acid, etc.) low molecular weight Available online at www.sciencedirect.com Clinical Biochemistry 42 (2009) 1001 – 1006 ⁎ Corresponding author. Fax: +39 095337036. E-mail addresses: lazzarig@unict.it, g.lazzarino@libero.it (G. Lazzarino). 0009-9120/$ - see front matter © 2009 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved. doi:10.1016/j.clinbiochem.2009.03.020