Research from our group showed that in obese Zucker rats, peritoneal macrophages present a local dysregulation in the constitutive or spontaneous release of pro-inflammatory cytokines such as IL-1β, INF-γ, IL-6, and TNF-α, contributing to the low-grade systemic pro-inflammatory state in obesity. This evidence concerns the gene IL6 and obesity due to melanocortin 4 receptor deficiency.