Abstract
Macrophage migration inhibitory factor (MIF) plays a pivotal role in systemic and local inflammatory and immune responses. The aim of this study is to assess MIF gene expression in PBMCs harvested from obese individuals and to compare it with that of lean subjects to analyze any potential relationship between resting metabolic rate as well as several different parameters and MIF expression in PBMC. We also aim to assess anti-inflammatory characteristics of vitamin D3 on MIF expression in vitro. Participants were 30 obese and 18 non-obese subjects who were assessed following an overnight fasting for RMR by means of indirect calorimetry. Body composition was measured using a Bodystat device. The PBMCs were separated from whole blood by the Ficoll-hypaque technique. The mRNA was extracted and the cDNA was synthesized. This process was followed by real-time PCR using primer pairs specific for MIF mRNA and beta actin as internal control. Our findings clearly demonstrate that there were significant differences in terms of BMI, BMR predict, fat proportion, fat mass, free fat mass, TBW, visceral fat, fasting serum glucose, TG, HDL, Hs-CRP and RMR between the two groups. Moreover, the level of MIF expression in the obese group was approximately 2.5 times higher compared to the lean group. An increased level of MIF expression in the obese group and a decreased expression of that non-obese was observed after inducing PBMCs with vitamin D3. One of the intriguing results of this study was the observed reverse correlation between MIF expression and fat mass as well as fat proportion after PBMCs were cultured in the presence of vitamin D3. Therefore, it could be concluded that MIF expression, which is in turn influenced by vitamin D3, has a role in the hyperactive immune profile and the pro-inflammatory state observed in obese individuals which is suggested to have a causal relationship with obesity.