Lipopolysaccharide Alters Thermogenic and Inflammatory Genes in White Adipose Tissue in Mice Fed Diets with Distinct 18-Carbon Fatty-Acid Composition.

Fatty acids are involved in the regulation of inflammatory responses in obesity. However, despite being the largest dietary fatty-acid class, effects of 18-carbon fatty acids with different degrees of saturation on inflammatory, metabolic, and thermogenic markers have not been well studied. Therefore, the objective of this study was to test if diets with different 18-carbon fatty-acid profiles differentially regulate inflammatory and metabolic genes. Male C57BL/6 mice were fed one of the four different diets: a control diet (CON) containing 5.6% kcal fat from lard and 4.4% kcal fat from soybean oil (CON) or three high-fat diets (HFD) containing 25% kcal fat from lard and 20% kcal fat from either shea butter oil (saturated fatty-acid-rich fat; shea butter [SHB]), olive oil (monounsaturated fatty-acid-rich fat; olive oil [OO]), or soybean oil (polyunsaturated fatty-acid-rich fat; soybean oil [SBO]) ad libitum for 4 weeks with or without a terminal 4-h lipopolysaccharide (LPS) treatment. Compared to CON, HFD-fed mice had higher weight gain and fat accumulation. The OO group had the highest brown adipose tissue (BAT) mass while the SBO group had higher Il6 and lower Cpt1a expression in white adipose tissue (WAT) than other HFD groups. Treatment with LPS upregulated expression of proinflammatory cytokines, and this was associated with downregulation of thermogenic gene expression. However, the diets did not have differential effects on inflammatory response to LPS. These data indicate that the saturation degree of 18-C fatty acids is not an important factor on response to LPS with regard to metabolic and inflammatory indicators.