Nutritional Supplementation With trans-10, cis-12–Conjugated Linoleic Acid Induces Inflammation of White Adipose Tissue

Nutritional Supplementation With trans -10, cis -12–Conjugated Linoleic Acid Induces Inflammation of White Adipose Tissue Hélène Poirier 1 , Jennifer S. Shapiro 2 , Roy J. Kim 2 and Mitchell A. Lazar 2 1 Physiologie de la Nutrition, Ecole Nationale Supérieure de Biologie Appliquée á la Nutrition et á l’Alimentation (ENSBANA), Unité Mixte de Recherche 5170 Centre Européen des Sciences du Goût (CESG)-Centre National de la Recherche Scientifique/Institut National de la Recherche Agronomique/Université de Bourgogne, Dijon, France 2 Division of Endocrinology, Diabetes, and Metabolism, Departments of Medicine, Genetics, and Pharmacology, and The Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania Address correspondence and reprint requests to Helene Poirier, PhD, Physiologie de la Nutrition, ENSBANA, Unité Mixte de Recherche 5170 CESG–Centre National de la Recherche Scientifique/Institut National de la Recherche Agronomique/Université de Bourgogne, Dijon, 21000 France. E-mail: hpoirier{at}u-bourgogne.fr Abstract Conjugated linoleic acids (CLAs) are conjugated dienoic isomers of linoleic acid. Many people supplement their diets with CLAs to attempt weight loss, and the trans -10, cis -12 isomer ( t10 , c12 -CLA) of CLA reduces adiposity in animal models and humans. However, CLA treatment in mice causes insulin resistance that has been attributed to the lipoatrophic state, which is associated with hyperinsulinemia and hepatic steatosis. Here, we investigated the effect of t10 , c12 -CLA on adipose tissue inflammation, another factor promoting insulin resistance. We confirmed that t10 , c12 -CLA daily gavage performed in mice reduces white adipose tissue (WAT) mass and adiponectin and leptin serum levels and provokes hyperinsulinemia. In parallel, we demonstrated that this CLA isomer led to a rapid induction of inflammatory factors such as tumor necrosis factor-α and interleukin-6 gene expression in WAT without affecting their serum levels. In vitro, t10 , c12 -CLA directly induced IL-6 secretion in 3T3-L1 adipocytes by an nuclear factor-κB–dependent mechanism. In vivo, however, the lipoatrophic adipose tissue of CLA-treated mice was notable for a dramatic increase in macrophage infiltration and gene expression. Thus, CLA supplementation directly induces inflammatory gene expression in adipocytes and also promotes macrophage infiltration into adipose tissue to a local inflammatory state that con