HR-MAS NMR SPECTROSCOPY FOR CHARACTERIZATION OF STEATOSIC LIVER: FAT QUANTIFICATION FOR A SPECTROSCOPIC DIFFERENTIATION BETWEEN STEATOSIS AND STEATOHEPATITIS

Non-alcoholic fatty liver disease (NAFLD) is a common cause of chronic liver disease. The NAFLD includes non-alcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH) [1]. The mechanisms of NAFL to NASH transition remain to be clarified [2]. NAFLD appears to originate from the dysregulation of hepatic lipid metabolism as a part of the metabolic syndrome accompanied by visceral obesity, dyslipidemia, atherosclerosis and insulin resistance. A recent study has also demonstrate that high prevalence of steatosis is correlated to HCV-related chronic hepatitis [3]. High Resolution Magic Angle Spinning (HR-MAS) NMR is a useful tool for the metabolic characterization of intact tissues [4] and can be used to support the clinical diagnosis. The first aim of this study is to characterize the NAFL and NASH metabolism using HR-MAS NMR Spectroscopy. The second one is to evaluate the possible transition from NAFLD to NASH quantifying the liver fat content (LFC), both in ex-vivo and in-vivo NMR Spectroscopy. Patients with indication for steatosis underwent in-vivo 1H MR Spectroscopy analysis and liver biopsy. Histopathological analysis provided steatosis percentage, steatosis grade and fibrosis. A fragment of biopsy specimen was used for HR-MAS analysis, to obtain metabolic tissue characterization. Univariate linear regression analysis and Pearson r coefficient were used to study the relationship between histological steatosis percentage and LFC, estimated through HR-MAS analysis and in-vivo Spectroscopy. Similar high associations were found between LFC estimated by HR-MAS and histological steatosis percentage (r=0,71; p=0,006) and between LFC estimated by in-vivo Spectroscopy and histological steatosis percentage (r=0,79; p=0,002). HR-MAS spectra showed a high tissue metabolic heterogeneity, with particular regard to the content of free glucose, alanine, glutamine/glutamate and phospholipids. Fibrotic liver showed a higher presence of small metabolites such as choline. HR-MAS NMR Spectroscopy, well estimates the fatty infiltration of the liver. Future research on HR-MAS spectral heterogeneity may allow to find biochemical metabolic indicators of steatosis progression to be used in the differentiation between steatohepatitis and steatosis through in-vivo MR Spectroscopy.[1] Contos M. J. and Sanyal A. J., The clinicopathologic spectrum an management of nonalcoholic fatty liver disease. Adv Anat Pathol, 9, 37-51 (2002).[2] Reid A. E., Nonalcoholic steatohepatitis . Gastroenterol, 121, 710-23 (2001).[3] Scheuer P. J., Ashrafzaddeh P., Sherlock S., Brown D., Disheiko G. M., the pathology of hepatitis C. Hepatology, 25, 567-71. (1992).[4] Righi V., Durante C., Cocchi M., Calabrese C., Di Febo G., Lecce F., Pisi A., Tugnoli V., Mucci A. and Schenetti L., Discrimination of healthy and neoplastic human colon tissues by ex vivo HR-MAS NMR spectroscopy and chemometric analyses. J of Proteome Res, 8, 1859-69 (2009).