Nitro-fatty acids are endogenous adaptive signaling mediators detected in animal and human urine, and plasma under basal conditions. Dietary supplementation with conjugated linoleic acid and nitrite/nitrate leads to gastric nitration and increased systemic and urinary levels. Moreover, in mice and rats, tissue levels are found to be elevated not only by gastric formation, but also by mitochondria driven in situ formation. Nitro fatty acids are pleiotropic signaling modulators that have demonstrated protective effects in a variety of pathological conditions including acute and chronic kidney disease, hypertension, heart and kidney ischemia reperfusion, sepsis, metabolic syndrome, diabetes and pulmonary hypertension amongst others. These modified fatty acids are electrophilic and exert their signaling actions by reacting with target proteins to activate Nrf2 and heat shock protein expression, inhibit NF-?B inflammatory signaling and associated fibrotic events. Despite the recent advances nitro fatty acid pharmacology, highly promising preclinical animal model data and undergoing clinical trials, our understanding of formation, absorption, distribution and protein targets is lagging behind. The main reasons for this slow pace were technical challenges associated with analyzing and characterizing biochemical aspects of this reactive species. Based on new evidence, we hypothesize that free NO2-CLA in plasma and tissues is a minor component of the total endogenous pool, represented by glycerol esterified and protein bound forms. These lipid and protein pools are dynamic, bioavailable and dictate transport, storage, signaling and metabolism. To demonstrate this hypothesis, the following Specific Aims are proposed:
Aim #1 Define the gastric formation, intestinal absorption and lipoprotein-dependent systemic distribution of NO2-CLA.
Aim #2 Evaluate the role of proteins on NO2-CLA transport, storage, plasma and tissue levels.
Aim #3 Establish the cardiac tissue distribution of exogenous and endogenous NO2-CLA and its functional protein targets in a rodent model of heart ischemia reperfusion. Overall, this proposal will provide quantitative information on NO2-CLA formation, mechanism of absorption and transport, spatial distribution and protein targets. The findings will directly impact not only the ongoing clinical programs but also how we understand the pharmacology of dietary electrophilic fatty acids.

Public Health Relevance

Components of our diets can have a significant impact on whole body homeostasis and regulation. In this regard, nitrated fatty acids are formed in the acidic gastric compartment from direct nitration reaction of unsaturated fatty acid and nitrite, the later typically present in leafy vegetables. Based on biochemical, cellular and animal experimental data showing protective, anti-inflammatory, anti-fibrotic and antioxidant effect, the use of nitrated fatty acid is now undergoing clinical trials for chronic kidney disease and pulmonary arterial hypertension. Five phase I clinical trials have been conducted for nitrated oleic acid and studies are being performed on conjugated linoleic acid plus nitrite/nitrates treatments in obese asthmatics. The rapid advance in these preclinical and clinical areas sharply contrast the paucity of information on formation, absorption, transport, tissue distribution and protein targets of nitrated fatty acids. Thus, we propose to define the formation yields of nitrated fatty acids in the gastric compartment, the role of incorporation into triglycerides and chylomicrons in their systemic transport and establish the protein targets that modulate their signaling activities. We expect to establish a comparison between the levels reached by dietary intervention and the values achieved in the clinic using pharmacological approaches, to have defined the mechanism of transport and the protein targets that mediate their signaling activities.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Special Emphasis Panel (ZRG1)
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Barski, Oleg
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University of Pittsburgh
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Freeman, Bruce A; O'Donnell, Valerie B; Schopfer, Francisco J (2018) The discovery of nitro-fatty acids as products of metabolic and inflammatory reactions and mediators of adaptive cell signaling. Nitric Oxide 77:106-111
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