title: Reduced dietary omega-6 to omega-3 fatty acid ratio and 12/15-lipoxygenase deficiency are protective against chronic high fat diet-induced steatohepatitis.
abstract: Obesity is associated with metabolic perturbations including liver and adipose tissue inflammation, insulin resistance, and type 2 diabetes. Omega-6 fatty acids (ω6) promote and omega-3 fatty acids (ω3) reduce inflammation as they can be metabolized to pro- and anti-inflammatory eicosanoids, respectively. 12/15-lipoxygenase (12/15-LO) enzymatically produces some of these metabolites and is induced by high fat (HF) diet. We investigated the effects of altering dietary ω6/ω3 ratio and 12/15-LO deficiency on HF diet-induced tissue inflammation and insulin resistance. We examined how these conditions affect circulating concentrations of oxidized metabolites of ω6 arachidonic and linoleic acids and innate and adaptive immune system activity in the liver. For 15 weeks, wild-type (WT) mice were fed either a soybean oil-enriched HF diet with high dietary ω6/ω3 ratio (11∶1, HFH), similar to Western-style diet, or a fat Kcal-matched, fish oil-enriched HF diet with a low dietary ω6/ω3 ratio of 2.7∶1 (HFL). Importantly, the total saturated, monounsaturated and polyunsaturated fat content was matched in the two HF diets, which is unlike most published fish oil studies in mice. Despite modestly increased food intake, WT mice fed HFL were protected from HFH-diet induced steatohepatitis, evidenced by decreased hepatic mRNA expression of pro-inflammatory genes and genes involved in lymphocyte homing, and reduced deposition of hepatic triglyceride. Furthermore, oxidized metabolites of ω6 arachidonic acid were decreased in the plasma of WT HFL compared to WT HFH-fed mice. 12/15-LO knockout (KO) mice were also protected from HFH-induced fatty liver and elevated mRNA markers of inflammation and lymphocyte homing. 12/15-LOKO mice were protected from HFH-induced insulin resistance but reducing dietary ω6/ω3 ratio in WT mice did not ameliorate insulin resistance or adipose tissue inflammation. In conclusion, lowering dietary ω6/ω3 ratio in HF diet significantly reduces steatohepatitis.
authors.affiliation: Department of Pediatrics, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Milos
authors.initials: M
authors.lastname: Lazic
authors.affiliation: Institute of Immunology, Genetics and Metabolism, CONICET-UBA, Buenos Aires, Argentina.
authors.forename: Maria Eugenia
authors.initials: ME
authors.lastname: Inzaugarat
authors.affiliation: Department of Pediatrics, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Davide
authors.initials: D
authors.lastname: Povero
authors.affiliation: Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Iris C
authors.initials: IC
authors.lastname: Zhao
authors.affiliation: Department of Medicine, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Mark
authors.initials: M
authors.lastname: Chen
authors.affiliation: Department of Medicine, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Madlena
authors.initials: M
authors.lastname: Nalbandian
authors.affiliation: Department of Medicine, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Yury I
authors.initials: YI
authors.lastname: Miller
authors.affiliation: Institute of Immunology, Genetics and Metabolism, CONICET-UBA, Buenos Aires, Argentina.
authors.forename: Alejandra C
authors.initials: AC
authors.lastname: Cherñavsky
authors.affiliation: Department of Pediatrics, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Ariel E
authors.initials: AE
authors.lastname: Feldstein
authors.affiliation: Department of Medicine, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Dorothy D
authors.initials: DD
authors.lastname: Sears
mesh_terms: D000818:Animals; D001092:Arachidonate 12-Lipoxygenase / Q000172:deficiency* / Q000235:genetics; D001093:Arachidonate 15-Lipoxygenase / Q000172:deficiency* / Q000235:genetics; D016718:Arachidonic Acid / Q000097:blood; D004032:Diet; D059305:Diet, High-Fat / Q000009:adverse effects*; D004435:Eating; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage*; D043371:Fatty Acids, Omega-6 / Q000008:administration & dosage*; D005234:Fatty Liver / Q000209:etiology / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D011163:Hydroxymethylbilane Synthase / Q000235:genetics; D008099:Liver / Q000378:metabolism / Q000473:pathology; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009765:Obesity / Q000209:etiology / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014280:Triglycerides / Q000378:metabolism; D001613:beta 2-Microglobulin / Q000235:genetics
chemical_list: C475064:12-15-lipoxygenase; D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6; D014280:Triglycerides; D001613:beta 2-Microglobulin; D016718:Arachidonic Acid; D001092:Arachidonate 12-Lipoxygenase; D001093:Arachidonate 15-Lipoxygenase; D011163:Hydroxymethylbilane Synthase