CXCR4 and obesity due to melanocortin 4 receptor deficiency: We indeed characterized the development of obesity and metabolic disorders in mice constitutively expressing fresh neutrophils (neutrophil selective CXCR2 deficiency, MRP8Cre+_CXCR2fl/fl) or aged neutrophils (neutrophil selective CXCR4 deficiency, MRP8Cre+_CXCR4fl/fl) after 20 weeks of feeding with a high fat diet (“HFD”).