Autofluorescence discrimination of metabolic fingerprint in nutritional and genetic fatty liver models

Liver tissue autofluorescence (AF) has been characterized in two models with a different potential to undergo disease progression to steatohepatitis: Wistar rats, administered with a methionine, choline deficient diet (MCD), and Zucker (fa/fa) rats, homozygous for a spontaneous mutation of leptin receptor. AF spectra were recorded from liver tissue cryostatic sections by microspectrofluorometry, under 366 nm excitation. Curve fitting analysis was used to estimate the contribution of different endogenous fluorophores (EFs) to the overall AF emission: i) fluorescing fatty acids, a fraction of liver lipids up to now poorly considered and complicated to detect by conventional procedures; ii) lipofuscin-like lipopigments, biomarkers of oxidizing events; iii) NAD(P)H and flavins, biomarkers of energy metabolism and tissue redox state. AF data and biochemical correlates of hepatocellular injury resulted to depend more on rat strain than on intratissue bulk lipid or ROS levels, reflecting a different metabolic ability of the two models to counteract potentially harmful agents. AF analysis can thus be proposed for extensive applications ranging from experimental hepatology to the clinics. AF based diagnostic procedures are expected to help both the prediction of the risk of fatty liver disease progression and the prescreening of marginal organs to be recruited as donors for transplantation. A support is also foreseen in the advancement and personalization of strategies to ameliorate the donor organ preservation outcome and the follow up of therapeutic interventions.