title: Mid-infrared fibre evanescent wave spectroscopy of serum allows fingerprinting of the hepatic metabolic status in mice.
abstract: Non-alcoholic fatty liver disease is associated with obesity, diabetes, and metabolic syndrome. The detection of systemic metabolic changes associated with alterations in the liver status during non-alcoholic fatty liver disease could improve patient follow-up. The aim of the present study was to evaluate the potential of mid-infrared fibre evanescent wave spectroscopy as a minimum-invasive method for evaluating the liver status during non-alcoholic fatty liver disease. Seventy-five mice were subjected to a control, high-fat or high-fat-high carbohydrate diets. We analysed the serum biochemical parameters and mRNA levels of hepatic genes by quantitative RT-PCR. Steatosis was quantified by image analysis. The mid-infrared spectra were acquired from serum, and then analysed to develop a predictive model of the steatosis level. Animals subjected to enriched diets were obese. Hepatic steatosis was found in all animals. The relationship between the spectroscopy-predicted and observed levels of steatosis, expressed as percentages of the liver biopsy area, was not linear. A transition around 10% steatosis was observed, leading us to consider two distinct predictive models (<10% and >10%) based on two different sets of discriminative spectral variables. The model performance was evaluated using random cross-validation (10%). The hypothesis that additional metabolic changes occur beyond this transition was supported by the fact that it was associated with increased serum ALT levels, and Col1α1 chain mRNA levels. Our data suggest that mid-infrared spectroscopy combined with statistical analysis allows identifying serum mid-infrared signatures that reflect the liver status during non-alcoholic fatty liver disease.
authors.affiliation: Univ. Bretagne Sud, IRDL, FRE CNRS 3744, CER Yves Coppens, BP573, 56017 Vannes, France. olivier.sire@univ-ubs.fr and DIAFIR, Avenue Chardonnet, Parc Lorans 26J, 35000 Rennes, France.
authors.forename: Maëna
authors.initials: M
authors.lastname: Le Corvec
authors.affiliation: INSERM UMR 991, F-35033 Rennes, France. olivier.loreal@univ-rennes1.fr.
authors.forename: Coralie
authors.initials: C
authors.lastname: Allain
authors.affiliation: LMBA, Laboratoire de Mathématiques de Bretagne Atlantique, UMR 6205, Univ. Bretagne Sud, 56017 Vannes, France.
authors.forename: Salim
authors.initials: S
authors.lastname: Lardjane
authors.affiliation: INSERM UMR 991, F-35033 Rennes, France. olivier.loreal@univ-rennes1.fr and University of Rennes 1, 35043, Rennes, France and CHU Rennes, Pole of Biology, University of Rennes 1, 35033 Rennes, France.
authors.forename: Thibault
authors.initials: T
authors.lastname: Cavey
authors.affiliation: INSERM UMR 991, F-35033 Rennes, France. olivier.loreal@univ-rennes1.fr and University of Rennes 1, 35043, Rennes, France and CHU Rennes, Department of Pathology, 35033 Rennes, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Turlin
authors.affiliation: INSERM UMR 991, F-35033 Rennes, France. olivier.loreal@univ-rennes1.fr and Histopathology Platform H2P2, UMS BioSite, 35043 Rennes, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Fautrel
authors.affiliation: INSERM UMR 991, F-35033 Rennes, France. olivier.loreal@univ-rennes1.fr and University of Rennes 1, 35043, Rennes, France.
authors.forename: Karima
authors.initials: K
authors.lastname: Begriche
authors.affiliation: IRMAR Mathematics Research Institute of Rennes, UMR-CNRS 6625, Rennes, France and INRIA/ASPI, Rennes, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Monbet
authors.affiliation: INSERM UMR 991, F-35033 Rennes, France. olivier.loreal@univ-rennes1.fr and University of Rennes 1, 35043, Rennes, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Fromenty
authors.affiliation: INSERM UMR 991, F-35033 Rennes, France. olivier.loreal@univ-rennes1.fr and University of Rennes 1, 35043, Rennes, France.
authors.forename: Patricia
authors.initials: P
authors.lastname: Leroyer
authors.affiliation: INSERM UMR 991, F-35033 Rennes, France. olivier.loreal@univ-rennes1.fr and University of Rennes 1, 35043, Rennes, France and CHU Rennes, Department of Rheumatology, 35033 Rennes, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Guggenbuhl
authors.affiliation: INSERM UMR 991, F-35033 Rennes, France. olivier.loreal@univ-rennes1.fr and CHU Rennes, Pole of Biology, University of Rennes 1, 35033 Rennes, France.
authors.forename: Martine
authors.initials: M
authors.lastname: Ropert
authors.affiliation: Univ. Bretagne Sud, IRDL, FRE CNRS 3744, CER Yves Coppens, BP573, 56017 Vannes, France. olivier.sire@univ-ubs.fr.
authors.forename: Olivier
authors.initials: O
authors.lastname: Sire
authors.affiliation: INSERM UMR 991, F-35033 Rennes, France. olivier.loreal@univ-rennes1.fr and University of Rennes 1, 35043, Rennes, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Loréal
mesh_terms: D000818:Animals; D008099:Liver / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D065626:Non-alcoholic Fatty Liver Disease / Q000097:blood* / Q000378:metabolism; D009765:Obesity; D013055:Spectrophotometry, Infrared