Given that obesity is considered a chronic state of low-grade inflammation (Zatterale et al., 2019), it was not surprising to observe considerable increases in the expression of inflammatory cytokines, IL-1 and IL-6, in adipocytes and macrophages in Negr1−/− mice (Figures 1A, B). Here, IL1B is linked to obesity due to melanocortin 4 receptor deficiency.