Obesity is a growing global health burden that strongly associates with several comorbidities including non- alcoholic fatty liver disease, hypertriglyceridemia, insulin resistance, and type 2 diabetes (T2D), reducing life expectancy and quality. Fish oil is an important dietary component that provides essential omega-3 fatty acids (?-3 FA) and is effective reducing severe hypertriglyceridemia. To better understand fish oil metabolites and their effects, a metabolomics approach on urine and serum of healthy volunteers taking Lovaza, a clinical grade FDA-approved omega-3 formulation, was performed. The furan CMPF was the major metabolite, followed by several other furans and their glucuronides. To evaluate its effects, mice fed a high-fat diet were administered CMPF to achieve levels equivalent to the ones observed in humans treated with Lovaza. CMPF lowered plasma and liver triglycerides and reduced hepatic steatosis, recapitulating the effects reported both in animals and in humans for Lovaza and fish oil treatments. The presence of furan fatty acids was confirmed in both fish oil and Lovaza. Moreover, we found furan fatty acid to bind and inhibit hepatic acetyl-CoA carboxylase, providing a mechanism of action. Based on these highly provocative preliminary results and current understanding, we hypothesize that fish oil furans are significant bioactive compounds responsible for fish oil-induced changes in hepatic lipid metabolism through acute modulation of metabolic pathways, in particular, inhibition of acetyl-CoA carboxylase. This hypothesis will be tested by pursuing the following Specific Aims Aim 1: Define FuFA levels in Lovaza and FO, dose, exposure and pharmacokinetics.
Aim 2 : Establish the role of FuFA on Lovaza-dependent TG reduction and NAFLD protection.
Aim 3 : Define hepatic protein targets, metabolic effects and role of ACC on FuFA protective effects. The development of mass spectrometry-based strategies to identify and characterize furans, application of thermal shift assay to determine binding partners, synthetic strategies, lipidomic studies and metabolomic assessments support a solid approach to definitively identify and characterize fish oil-derived bioactive furans. Synthetic furan fatty acids will be tested in a rat model of diet-induced obesity and evaluated in the context of ?-3 FA. A successful completion of this proposal will have defined the participation and role of furans in the beneficial effects described for fish oil. These are potent dietary ACC inhibitors present in fish oil at pharmacologically relevant concentrations and are qualified impurities with a safe toxicological profile. This proposal is designated to fill critical gaps in knowledge in ?-3 FA therapeutics and can potentially re- define current paradigms related to the impact of ?-3 FA supplementation on lipogenesis, lipolysis, and glycolysis.

Public Health Relevance

Obesity is a global health burden that associates with important comorbidities including non-alcoholic fatty liver disease, hypertriglyceridemia and type 2 diabetes (T2D), thus reducing life expectancy and quality. Paradoxically, fish oil-derived diets rich in omega-3 fatty acids have shown to prevent liver steatosis and hypertriglyceridemia and reduce fat accumulation in human and animal models. We recently discovered that CMPF, a major metabolite of fish oil intake, causes a metabolic switch in the liver using high-fat diet and genetic models resulting in reduced lipogenesis, decreased liver and plasma triglycerides and protection against steatosis, paralleling the overall effects of fish oil observed in human and animal models. Moreover, the levels of CMPF that induced these effects in animals were similar to the levels of CMPF we found in humans after clinical administration of FDA-approved omega-3 treatments to healthy subjects. CMPF is a metabolic product of furans present as minor components (~3%) of fish oil and in omega-3 prescription drugs (Lovaza Vascepa). We found that furan-CoA derivatives bind to acetyl-CoA carboxylase (ACC) in liver homogenates and are potent inhibitors of this key enzyme that defines metabolic pathways and de novo lipogenesis in the liver. This led to propose the hypothesis that furans present in fish oil are responsible for the clinical benefits associated with fish oil administration. This proposal will establish the pharmacology and mechanism of action of furan fatty acids in the context of fish oil treatments in an obese rat model. To establish the furan targets and define its metabolic effects, state of the art proteomic and metabolomic approaches will be used based on thermal stability and steady state flux analysis. A successful completion of this proposal may greatly impact our current understanding of fish oil effect. Moreover, it will fill critical gaps in knowledge in ?-3 FA therapeutics and can potentially re-define current paradigms related to the impact of ?-3 FA supplementation on lipogenesis, lipolysis, and glycolysis. Finally, this proposal may lead to the development of novel pharmacological approaches for the treatment of non-alcoholic fatty liver disease, hypertriglyceridemia and hepatic steatosis based of furans that have already been proven to have a safe pharmacological profile.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Research Project (R01)
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Integrative Physiology of Obesity and Diabetes Study Section (IPOD)
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Doo, Edward
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University of Pittsburgh
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Hansen, Anne Louise; Buchan, Gregory J; Rühl, Michael et al. (2018) Nitro-fatty acids are formed in response to virus infection and are potent inhibitors of STING palmitoylation and signaling. Proc Natl Acad Sci U S A 115:E7768-E7775
Schopfer, Francisco J; Vitturi, Dario A; Jorkasky, Diane K et al. (2018) Nitro-fatty acids: New drug candidates for chronic inflammatory and fibrotic diseases. Nitric Oxide 79:31-37