Short-term flaxseed oil, rich in omega 3, protects mice against metabolic damage caused by high-fat diet, but not inflammation

It is known that long-term high-fat diet (HF) feeding drastically affects the adipose tissue, contributing to metabolic disorders. Recently, short-term HF consumption was shown to affect different neuronal signaling pathways. Thus, we aimed to evaluate the inflammatory effects of a short-term HF and whether a diet containing omega-3 fatty acid fats from flaxseed oil (FS) has protective effects. Mice were divided into three groups for 3 d, according to their diets: Control group (CT), HF, or FS for 3 d. Lipid profiles were assessed through mass spectrometry and inflammatory markers by RT-qPCR and Western blotting. After short-term HF, mice increased food intake, body weight, adiposity, and fasting glucose. Increased mRNA content of Ccl2 and Tnf was demonstrated in the HF compared to CT in mesenteric adipose tissue. In the liver, TNFα protein was higher in the HF group than in CT, followed by a decreased polyunsaturated fatty acids tissue incorporation in HF. On the other hand, the consumption of FS reduced food intake and fasting glucose, as well as increased omega-3 fatty acid incorporation in MAT and the liver. However, short-term FS was insufficient to control the early inflammation triggered by HF in MAT and the liver. These data demonstrated that a 3-d HF diet is enough to damage glucose homeostasis and trigger inflammation. In contrast, short-term FS protects against increased food intake and fasting glucose but not inflammation in mice.

Omega-3 mechanism of action in inflammation and endoplasmic reticulum stress in mononuclear cells from overweight non-alcoholic fatty liver disease participants: study protocol for the "Brazilian Omega Study" (BROS)-a randomized controlled trial

Abstract

The low-grade inflammation is pivotal in obesity and its comorbidities; however, the inflammatory proteins are out of target for traditional drug therapy. Omega-3 (ω3) fatty acids can modulate the downstream signaling of Toll-like receptor (TLR) and tumor necrosis factor-α receptor (TNFα) through GPR120, a G-protein-coupled receptor, a mechanism not yet elucidated in humans. This work aims to investigate if the ω3 supplementation, at a feasible level below the previously recommended level in the literature, is enough to disrupt the inflammation and endoplasmic reticulum stress (ER-stress), and also if in acute treatment (3 h) ω3 can activate the GPR120 in peripheral blood mononuclear cells (PBMC) and leukocytes from overweight non-alcoholic fatty liver disease (NAFLD) participants. The R270H variant of the Ffar4 (GPR120 gene) will also be explored about molecular responses and blood lipid profiles. A triple-blind, prospective clinical trial will be conducted in overweight men and women, aged 19–75 years, randomized into placebo or supplemented (2.2 g of ω3 [EPA+DHA]) groups for 28 days. For sample calculation, it was considered the variation of TNFα protein and a 40% dropout rate, obtaining 22 individuals in each group. Volunteers will be recruited among patients with NAFLD diagnosis. Anthropometric parameters, food intake, physical activity, total serum lipids, complete fatty acid blood profile, and glycemia will be evaluated pre- and post-supplementation. In the PBMC and neutrophils, the protein content and gene expression of markers related to inflammation (TNFα, MCP1, IL1β, IL6, IL10, JNK, and TAK1), ER-stress (ATF1, ATF6, IRE1, XBP1, CHOP, eIF2α, eIF4, HSP), and ω3 pathway (GPR120, β-arrestin2, Tab1/2, and TAK1) will be evaluated using Western blot and RT-qPCR. Participants will be genotyped for the R270H (rs116454156) variant using the TaqMan assay. It is hypothesized that attenuation of inflammation and ER-stress signaling pathways in overweight and NAFLD participants will be achieved through ω3 supplementation through binding to the GPR120 receptor.

Trial registration

ClinicalTrials.gov #RBR-7x8tbx. Registered on May 10, 2018, with the Brazilian Registry of Clinical Trials.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05702-x.