CCL2 (C-C Motif Chemokine Ligand 2) was down-regulated in the ICU patients as was CX3CR1 (C-X3-C Motif Chemokine Receptor 1), which is associated with obesity, a risk factor for severe influenza disease (60). Here, CX3CR1 is linked to obesity due to melanocortin 4 receptor deficiency.