Effects of interleukin-4 on energy metabolism
Yih-Hsin Chang1, Kuo-Ting Ho2 & Ming-Yuh Shiau3
Abundant evidence has demonstrated that long-term cytokine-mediated inflammation is a risk factor for obesity and type 2 diabetes mellitus. In this study, we focused on investigating the putative involvement of Th2-derived cytokine, interleukin-4 (IL-4), in energy metabolism. Mice were i.p. injected with adenovirus containing full-length IL-4 gene, or with recombinant mouse IL-4 every other day for 8 weeks. Effects of IL-4 on energy metabolism in insulin-target cells and blood chemistry were examined. Significantly higher levels of phosphorylated-AKT were observed in skeletal muscle from mice with IL-4 administration (P≤0.002 versus control mice). In addition, IL-4 treatment resulted in a significant attenuation of glycogen synthase kinase phosphorylation in skeletal muscle (P≤0.01 versus control mice) and adipose tissues (P=0.032 versus control mice). Serum levels of free fatty acid were elevated while number of epididymal fat- and liver-infiltrated macrophages were increased by IL-4 treatment. The above results suggested that IL-4 could affect glucose and lipid reservoir by regulate important signaling mediators of energy metabolism in insulin target cells.