Tomato Juice Consumption Modifies the Urinary Peptide Profile in Sprague-Dawley Rats with Induced Hepatic Steatosis

Abstract

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disorder in Western countries, with a high prevalence, and has been shown to increase the risk of type 2 diabetes, cardiovascular disease (CVD), etc. Tomato products contain several natural antioxidants, including lycopene-which has displayed a preventive effect on the development of steatosis and CVD. Accordingly, the aim of the present work was to evaluate the effect of tomato juice consumption on the urinary peptide profile in rats with NAFLD induced by an atherogenic diet and to identify potential peptide biomarkers for diagnosis. Urine samples, collected weekly for four weeks, were analyzed by capillary electrophoresis (CE) coupled to a mass spectrometer (MS). A partial least squares-discriminant analysis (PLS-DA) was carried out to explore the association between differential peptides and treatments. Among the 888 peptides initially identified, a total of 55 were obtained as potential biomarkers. Rats with steatosis after tomato juice intake showed a profile intermediate between that of healthy rats and that of rats with induced hepatic steatosis. Accordingly, tomato products could be considered as a dietary strategy for the impairment of NAFLD, although further research should be carried out to develop a specific biomarkers panel for NAFLD.

Keywords: biomarkers; capillary electrophoresis coupled to a mass spectrometer (CE-MS); diagnosis; liver; non-alcoholic fatty liver disease (NAFLD); peptidome; proteome; tomato; urine.

Figure 1

sPLS-DA model representing the four experimental groups in two components according to their peptide profile. NA: standard diet and water; NL: standard diet and tomato juice; HA: hypercholesterolemic and high-fat diet and water; HL: hypercholesterolemic and high-fat diet and tomato juice; Component 1: diet and Component 2: beverage.

Figure 2

Urinary peptide fingerprints of groups control, NA and NL. The CE migration time (min) (X-axis) is plotted against the molecular mass (kDa) on a logarithmic scale (Y-axis). The Z-axis represents the mean signal intensity. W1–4: Week 1–4.

Figure 3

Compiled CE-MS urinary peptide fingerprints of groups N, HA and HL over the weeks. The CE migration time (min) (X-axis) is plotted against the molecular mass (kDa) on a logarithmic scale (Y-axis). The Z-axis represents the mean signal intensity. N: standard diet; CE: capillary electrophoresis.

Figure 4

Box-and-whisker plots of component 1 for the three experimental groups (N, HA and HL) over four weeks.