CCL4 and obesity due to melanocortin 4 receptor deficiency: For example, although programmed death ligand (PD-L) 1, chemokine ligand (CCL)2, CCL4, interleukin 8 (IL-8), IL-1 receptor antagonist (IL-1ra), interferon gamma (IFNγ), cluster of differentiation 40 ligand (CD40-L), and IFNγ–induced protein (IP-10) are all upregulated in obesity, the effects of weight loss and dietary interventions on these biomarkers have been understudied.