TFRC and obesity due to melanocortin 4 receptor deficiency: However, by 6 months, we saw both a reduction of CD71 and an increase in ICAM-1 expression in alveolar macrophages from the HFD group suggesting an evolution of macrophage polarization toward M1 or metabolically-activated cells associated with diet-induced obesity as has been reported in other tissues (Fig. 3b) [11, 12, 15].