NCR1 and obesity due to melanocortin 4 receptor deficiency: Moreover, obesity drove an upregulation of ligands of the activating receptor NKp46 on adipocytes of obese mice, which stimulated the proliferation and IFN-γ secretion of NK cells and, consequently, the polarization from the anti-inflammatory M2 macrophages to the pro-inflammatory M1 macrophages (135).