Rutin Suppresses Palmitic Acids-Triggered Inflammation in Macrophages and Blocks High Fat Diet-Induced Obesity and Fatty Liver in Mice

To elucidate the mechanism of rutin in blocking macrophage-mediated inflammation and high fat diet-induced obesity and fatty liver. Both in vitro and in vivo approaches were taken in evaluating the effects of rutin on palmitic acids-triggered inflammation in cultured macrophages, and on weight gain and development of fatty liver of mice fed a high fat diet. Palmitic acids increase mRNA levels of pro-inflammatory cytokines, and elevate the production of TNF alpha in cultured macrophages. Pre-exposure of rutin to cells greatly suppressed these elevations. The suppressed inflammation by rutin was correlated with a decrease in transcription of genes responsible for ER stress and production of reactive oxygen species. In vivo, rutin protects mice from high fat diet-induced obesity, fatty liver and insulin resistance. The protective effects were associated with lack of hypertrophy and crown-like structures in the white adipose tissue, decreased mRNA levels of marker genes for macrophages including F4/80, Cd11c and Cd68, and repressed transcription of genes involved in chronic inflammation such as Mcp1 and Tnf alpha in white adipose tissue. In addition, rutin increases the expression of genes responsible for energy expenditure in brown adipose tissue including Pgc1 alpha and Dio2. Furthermore, rutin suppresses transcription of Srebp1c and Cd36 in the liver, leading to a blockade of fatty liver development. These results suggest that supplementation of rutin is a promising strategy for blocking macrophage-mediated inflammation and inflammation-induced obesity and its associated complications.