MSR1 and obesity due to melanocortin 4 receptor deficiency: Because obesity is associated with macrophage accumulation and chronic inflammation, Zhu et al. assessed ATMs to explain their metabolic phenotype in HFD Msr1+/+ and Msr1−/− mice and showed a decrease in resident CD11c− ATMs and an increase in proinflammatory CD11c+ ATMs in Msr1−/−ob/ob mice25.