TNF and obesity due to melanocortin 4 receptor deficiency: In addition, NK cell suppression using either neutralizing antibodies or E4bp4 heterozygous knockout mice was found to improve adipose tissue macrophage inflammation and obesity-induced insulin resistance as well as to decrease the expression of pro-inflammatory cytokines such as IL-6 and TNF, which are elevated in the VAT of HFD-fed mice [54].