Overview of Macrophage Migration Inhibitory Factor (MIF) as a Potential Biomarker Relevant to Adiposity

The cytokine "macrophage migration inhibitory factor (MIF)" is generally recognized as a proinflammatory cytokine, and MIF is involved in broad range of acute and chronic inflammatory states. With regard to glucose metabolism and insulin secretion, MIF is produced by pancreatic β cells and acts as a positive regulator of insulin secretion. In contrast, it is evident that MIF expressed in adipose tissues causes insulin resistance. Concerning MIF gene analysis, we found four alleles: 5-, 6-, 7-and 8-CATT at position -794 of MIF gene in a Japanese population. Genotypes without the 5-CATT allele were more common in the obese subjects than in the lean or overweight groups. It is conceivable that promoter polymorphism in the MIF gene is profoundly linked with obesity relevant to lifestyle diseases, such as diabetes. Obesity has become a serious social issue due to the inappropriate nutritional balance, and the consumption of functional foods (including functional foods to reduce fat mass) is expected to overcome this issue. In this context, MIF would be a reliable quantitative biomarker to evaluate the effects of functional foods on adiposity.