Macrophage migration inhibitory factor (MIF) is a cytokine that is increased in obesity and contributes to metabolic dysfunction. Our present study describes a novel mechanism by which fatty acids activate non-immune cells to increase MIF secretion in adipose tissue, initiating cross-talk between preadipocytes and adipocytes. High fatty acids specifically induce protease-activated receptor 2 (PAR2) activation in preadipocytes, which downregulates pref-1 expression and release. Preadipocyte factor 1 (Pref-1) has an autocrine-paracrine action to inhibit the release of MIF from both preadipocytes and adipocytes. Thus, the loss of Pref-1 secretion during high fat feeding is responsible in part for both increased MIF secretion in adipose tissue and the rise in plasma MIF levels that ensues. The physiological consequences are most evident in adipose tissue. Genetic deletion of Par2 confirms the importance of this mechanism in mice, protecting against high fat diet-induced metabolic dysfunction. Importantly, this novel mechanism is also operative in adipose tissue from obese human subjects. These results provide the scientific rationale to consider whether strategies to either block Par2 expression or augment Pref-1 secretion might improve metabolic health in obesity or type 2 diabetes.


Y. Huang: None. L. Chen: None. Y. Qi: None. D. Qi: None.

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