Research Paper CMPF, a Metabolite Formed Upon Prescription Omega-3-Acid Ethyl Ester Supplementation, Prevents and Reverses Steatosis Kacey J. Prentice a,1 , Stacy G. Wendell b,1 , Ying Liu a , Judith A. Eversley a , Sonia R. Salvatore b , Haneesha Mohan a , Sydney L. Brandt a , Andrew C. Adams c , X. Serena Wang a , David Wei a , Garret A. FitzGerald d,e , Timothy B. Durham c , Craig D. Hammond c , Kyle W. Sloop c , Carsten Skarke d,e, ⁎ ,2 , Francisco J. Schopfer b, ⁎⁎ ,2 , Michael B. Wheeler a, ⁎⁎⁎ ,2 a Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada b Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA c Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, USA d Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA, USA e Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA abstract article info Article history: Received 18 August 2017 Received in revised form 14 December 2017 Accepted 15 December 2017 Available online 19 December 2017 Prescription ω-3 fatty acid ethyl ester supplements are commonly used for the treatment of hypertriglyc- eridemia. However, the metabolic profile and effect of the metabolites formed by these treatments remain un- known. Here we utilized unbiased metabolomics to identify 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF) as a significant metabolite of the ω-3-acid ethyl ester prescription Lovaza™ in humans. Administra- tion of CMPF to mice before or after high-fat diet feeding at exposures equivalent to those observed in humans increased whole-body lipid metabolism, improved insulin sensitivity, increased beta-oxidation, reduced lipogenic gene expression, and ameliorated steatosis. Mechanistically, we find that CMPF acutely inhibits ACC ac- tivity, and induces long-term loss of SREBP1c and ACC1/2 expression. This corresponds to an induction of FGF21, which is required for long-term steatosis protection, as FGF21KO mice are refractory to the improved metabolic effects. Thus, CMPF treatment in mice parallels the effects of human Lovaza™ supplementation, revealing that CMPF may contribute to the improved metabolic effects observed with ω-3 fatty acid prescriptions. © 2017 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). 1. Introduction Excessive caloric intake combined with increasingly sedentary lifestyles is producing an epidemic of overweight and obesity, affecting nearly 40% of Americans (Cameron et al., 2004). The cluster of metabolic disturbances associated with increased adiposity, termed metabolic syn- drome (MetS), confers a 1.6-fold increased risk of mortality (O'Neill and O'Driscoll, 2015), attributed to consequential risk for diabetes (5-fold), stroke (2- to 4-fold), myocardial infarction (3- to 4-fold) and cancer in MetS individuals (Eckel et al., 2005; Masters et al., 2013a; Masters et al., 2013b; Micucci et al., 2016; O'Neill and O'Driscoll, 2015). The under- lying pathophysiology of MetS is primarily based in dysregulated lipid metabolism, resulting in aberrant lipid storage in the liver and muscle, hypertriglyceridemia, increased insulin resistance, and altered circulat- ing lipoprotein levels (Avramoglu et al., 2006; Bergman and Ader, 2000; Cao et al., 2008; Ginsberg, 2006). Fish oil (FO) is mainly composed of ω-3 fatty acids (ω-3 FA) and its administration consistently demonstrates beneficial metabolic effects that include lowering of plasma triglycerides (TG) in a dose-dependent manner (Imaichi et al., 1963; Kinsell et al., 1961; Shearer et al., 2012) which results in long-term beneficial effects on many aspects of MetS (Koski, 2008). Lovaza™ is a prescription ω-3-acid ethyl ester supple- ment (comprised of approximately 55.1% EPA, 44.9% DHA) approved for the lowering of TG in patients with plasma TG levels ranging be- tween 500 and 2000 mg/dl (Koski, 2008). Clinical studies at the recom- mended dose of 4 g/day of Lovaza™ for 6–16 wks resulted in an average drop of 42% in TG levels compared to placebo (Harris et al., 1997; Koski, 2008; Pownall et al., 1999). There are several proposed mechanisms EBioMedicine 27 (2018) 200–213 ⁎ Correspondence to: Carsten Skarke, 3600 Spruce St, 8036 Maloney Bldg., University of Pennsylvania, Philadelphia, PA 19104, USA. ⁎⁎ Correspondence to: Francisco J. Schopfer, 200 Lothrop Street, E1340 Thomas E. Starzl Biomedical Science Tower, Pittsburgh, PA 15213, USA. *** Correspondence to: Michael B Wheeler, 1 King's College Circle, MSB3352, Toronto, ON M5S 1A8, Canada. E-mail addresses: cskarke@pennmedicine.upenn.edu (C. Skarke), fjs2@pitt.edu (F.J. Schopfer), michael.wheeler@utoronto.ca (M.B. Wheeler). 1 Co-First Authors. 2 Co-Corresponding Authors. https://doi.org/10.1016/j.ebiom.2017.12.019 2352-3964/© 2017 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Contents lists available at ScienceDirect EBioMedicine journal homepage: www.ebiomedicine.com