Transgenic restoration of long-chain n-3 fatty acids in insulin target tissues improves resolution capacity and alleviates obesity-linked inflammation and insulin resistance in high-fat-fed mice.
OBJECTIVE
The catabasis of inflammation is an active process directed by n-3 derived pro-resolving lipid mediators. We aimed to determine whether high-fat (HF) diet-induced n-3 deficiency compromises the resolution capacity of obese mice and thereby contributes to obesity-linked inflammation and insulin resistance.


METHODS
We used transgenic expression of the fat-1 n-3 fatty acid desaturase from C. elegans to endogenously restore n-3 fatty acids in HF-fed mice. After 8 weeks on HF or chow diets, wild-type and fat-1 transgenic mice were subjected to insulin and glucose tolerance tests and a resolution assay was performed. Metabolic tissues were then harvested for biochemical analyses.


RESULTS
We report that the n-3 docosanoid resolution mediator protectin D1 is lacking in muscle and adipose tissue of HF-fed wild-type mice. Accordingly, HF-fed wild-type mice have an impaired capacity to resolve an acute inflammatory response and display elevated adipose macrophage accrual and chemokine/cytokine expression. This is associated with insulin resistance and higher activation of iNOS and JNK in muscle and liver. These defects are reversed in HF-fed fat-1 mice, in which the biosynthesis of this important n-3 docosanoid resolution mediator is improved. Importantly, transgenic restoration of n-3 fatty acids prevented obesity-linked inflammation and insulin resistance in HF-fed mice without altering food intake, weight gain, or adiposity.


CONCLUSIONS
We conclude that inefficient biosynthesis of n-3 resolution mediators in muscle and adipose tissue contributes to the maintenance of chronic inflammation in obesity and that these novel lipids offer exciting potential for the treatment of insulin resistance and diabetes.
White
Phillip J
PJ
Department of Medicine, Faculty of Medicine, Cardiology axe, Quebec Heart and Lung Institute, CHUQ Research Centre, and INAF, Laval University, Quebec, Canada.
Arita
Makoto
M
Taguchi
Ryo
R
Kang
Jing X
JX
Marette
André
A
D000818:Animals; D004041:Dietary Fats / Q000494:pharmacology*; D005227:Fatty Acids / Q000032:analysis; D015525:Fatty Acids, Omega-3 / Q000378:metabolism* / Q000627:therapeutic use; D007249:Inflammation / Q000517:prevention & control*; D007333:Insulin Resistance / Q000502:physiology*; D008055:Lipids / Q000737:chemistry; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009765:Obesity / Q000150:complications / Q000503:physiopathology* / Q000517:prevention & control; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D004041:Dietary Fats; D005227:Fatty Acids; D015525:Fatty Acids, Omega-3; D008055:Lipids; D014409:Tumor Necrosis Factor-alpha