CCL2 and obesity due to melanocortin 4 receptor deficiency: As shown in Figure 6, single-nucleus RNA sequencing (snRNA-seq) has revealed the presence of a distinct macrophage subpopulation in obesity-associated adipose tissue—namely, inflammatory and metabolically activated macrophages (IMAMs) characterized by high expression of ATF4, PDIA3, Acyl-CoA Synthetase Long Chain Family Member 4 (ACSL4), and C-C Motif Chemokine Ligand 2 (CCL2) (ATF4hiPDIA3hiACSL4hiCCL2hi) [126].