Caffeic Acid Phenethyl Ester Suppresses the Production of Pro-inflammatory Cytokines in Hypertrophic Adipocytes through Lipopolysaccharide-Stimulated Macrophages

Obesity is a condition in which excess body fat accumulates due to lipids producing adipocytes and an increased number of differentiated mature cells. Recently, new findings have shown that macrophages infiltrate into adipose tissues and produce various pro-inflammatory cytokines in obese subjects. The inflammatory changes induced by the cross-talk between adipocytes and macrophages are critical for the pathophysiology of obesity and thus of metabolic syndrome. Caffeic acid phenethyl ester (CAPE) is known to have many functions, including antibacterial, anticancer and anti-inflammatory properties, but there is no evidence of its effect on the inflammatory responses in hypertrophic adipocytes through stimulation by macrophages. We investigated the effect of CAPE on macrophages and hypertrophic adipocytes in this study. CAPE significantly suppressed the levels of lipopolysaccharide (LPS)-induced interleukin (IL)-1-beta, tumor necrosis factor (TNF)-alpha and monocyte chemoattractant protein (MCP)-1 from a macrophage cell line, RAW264.7. Supernatants of stimulated RAW264.7 macrophages drastically increased mRNA levels of pro-inflammatory cytokines such as IL-6, MCP-1 and TNF-alpha in 3T3-L1 hypertrophic adipocytes. CAPE also significantly and dose-dependently reduced the gene expression of these cytokines. Our findings indicate that CAPE has inhibitory effects on the production of pro-inflammatory cytokines from LPS-stimulated RAW264.7 macrophages. In addition, CAPE suppressed gene expressions of cytokines under inflammatory conditions of hypertrophic adipocytes, suggesting that it may have the potential to suppress inflammation by macrophage infiltration into adipose tissue in obese patients.