Monounsaturated Fatty Acid-Enriched High-Fat Diets Impede Adipose NLRP3 Inflammasome-Mediated IL-1β Secretion and Insulin Resistance Despite Obesity

Saturated fatty acid (SFA) high-fat diets (HFDs) enhance interleukin (IL)-1 beta-mediated adipose inflammation and insulin resistance. However, the mechanisms by which different fatty acids regulate IL-1 beta and the subsequent effects on adipose tissue biology and insulin sensitivity in vivo remain elusive. We hypothesized that the replacement of SFA for monounsaturated fatty acid (MUFA) in HFDs would reduce pro-IL-1 beta priming in adipose tissue and attenuate insulin resistance via MUFA-driven AMPK activation. MUFA-HFD-fed mice displayed improved insulin sensitivity coincident with reduced pro-IL-1 beta priming, attenuated adipose IL-1 beta secretion, and sustained adipose AMPK activation compared with SFA-HFD-fed mice. Furthermore, MUFA-HFD-fed mice displayed hyperplastic adipose tissue, with enhanced adipogenic potential of the stromal vascular fraction and improved insulin sensitivity. In vitro, we demonstrated that the MUFA oleic acid can impede ATP-induced IL-1 beta secretion from lipopolysaccharide- and SFA-primed cells in an AMPK-dependent manner. Conversely, in a regression study, switching from SFA- to MUFA-HFD failed to reverse insulin resistance but improved fasting plasma insulin levels. In humans, high-SFA consumers, but not high-MUFA consumers, displayed reduced insulin sensitivity with elevated pycard-1 and caspase-1 expression in adipose tissue. These novel findings suggest that dietary MUFA can attenuate IL-1 beta-mediated insulin resistance and adipose dysfunction despite obesity via the preservation of AMPK activity.