ORIGINAL ARTICLE Unraveling the adipocyte inflammomodulatory pathways activated by North American ginseng SAF Wilson 1 , MHT Wong 2 , C Stryjecki 1 , A De Boer 1 , EMK Lui 3 and DM Mutch 1 BACKGROUND: North American (NA) ginseng (Panax quinquefolius) is a popular natural health product (NHP) that has been demonstrated to regulate immune function, inflammatory processes and response to stress and fatigue. Recent evidence suggests that various extracts of NA ginseng may have different bioactivities because of distinct profiles of ginsenosides and polysaccharides. To date, the bioactive role of ginseng on adipocytes remains relatively unexplored. OBJECTIVE: The goal of this work was to study the extract-specific bioactivity of NA ginseng on differentiated preadipocyte gene expression and adipocytokine secretion. METHODS: In vitro differentiated 3T3-L1 preadipocytes were treated with 25 and 50 mg ml  1 of either crude ethanol (EtOH) or aqueous (AQ) NA ginseng extracts, or polysaccharide and ginsenoside extracts isolated from the AQ extract. Global gene expression was studied with microarrays and the resulting data were analyzed with functional pathway analysis. Adipocytokine secretion was also measured in media. RESULTS: Pathway analysis indicated that the AQ extract, and in particular the polysaccharide extract, triggered a global inflammomodulatory response in differentiated preadipocytes. Specifically, the expression of Il-6 (interleukin 6), Ccl5 (chemokine (C–C motif) ligand 5), Nfkb (nuclear factor-kappaB) and Tnfa (tumor necrosis factor alpha) was increased. These effects were also reflected at the protein level through the increased secretion of IL-6 and CCL5. No effect was seen with the EtOH extract or ginsenoside extract. Using a specific toll-like receptor 4 (TLR4) inhibitor reduced the upregulation of inflammatory gene expression, indicating the relevance of this pathway for the signaling capacity of NA ginseng polysaccharides. CONCLUSION: This work emphasizes the distinct bioactivities of different ginseng extracts on differentiated preadipocyte signaling pathways, and highlights the importance of TLR4 for mediating the inflammomodulatory role of ginseng polysaccharides. International Journal of Obesity (2013) 37, 350–356; doi:10.1038/ijo.2012.50; published online 17 April 2012 Keywords: 3T3-L1 adipocyte; North American ginseng; inflammation; TLR4; microarray INTRODUCTION The medicinal properties of plants have been exploited for centuries for the prevention and treatment of disease; however, the genetic and molecular basis for their use remains poorly understood. A prime example is ginseng, which is widely consumed to boost the immune system, as well as provide resistance to stress and fatigue. 1 Ginseng constitutes a family of herbs in which the primary species are Panax ginseng and Panax quinquefolius. P. ginseng (more commonly known as Asian ginseng) is widely considered to be an adaptogen, mental stimulant and general wellness tonic. 2,3 In contrast, considerably less is known about the bioactivity of P. quinquefolius (more commonly known as North American (NA) ginseng). Although similar in genus, these species have distinct profiles of bioactive compounds, such as ginsenosides and polysaccharides. 4 Polysaccharides and ginsenosides differ in their physico- chemical structures, which therefore affects their solubility in extraction solvents. 3,4 These compounds are also thought to differ in their ability to modulate cellular signaling pathways. 4,5 For example, ginsenosides are characterized as steroidal saponins and share structural similarities with steroid hormones. As such, ginsenosides are thought to interact with ion channels, as well as membrane and nuclear receptors. Further evidence suggests that ginsenosides may also alter membrane fluidity. 4 In contrast, plant polysaccharides are thought to exert their activity primarily by binding plasma membrane receptors that activate intracellular signaling cascades, leading to altered gene expression. 5 Initial research has demonstrated that NA ginseng extracts can regulate immune function, inflammatory processes and glucose homeostasis. 3,6 For example, treating macrophage with aqueous (AQ) ginseng extracts led to a significant increase in the production of several cytokines, such as interleukin 6 (IL-6), tumor necrosis factor alpha (TNFa) and nitric oxide. 3 IL-6 and TNFa have been described as pro-inflammatory cytokines that are involved in a number of functions, including cell cycle regulation, differentiation and metabolic pathways such as insulin signaling. 7,8 It appears that this inflammodulation may be beneficial when ginseng is provided as an acute treatment, as demonstrated with upper respiratory infections; however, the consequences of long-term treatment have not been fully investigated. 9 The use of NHPs by individuals attempting to lose excess body weight has become more prominent in recent years. 10 Obesity is recognized as a chronic state of low-grade inflammation that is 1 Department of Human Health and Nutritional Sciences, The University of Guelph, Guelph, Ontario, Canada; 2 Department of Mathematics and Statistics, The University of Guelph, Guelph, Ontario, Canada and 3 Department of Physiology and Pharmacology - Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada. Correspondence: Professor DM Mutch, Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada. E-mail: dmutch@uoguelph.ca Received 13 December 2011; revised 31 January 2012; accepted 6 March 2012; published online 17 April 2012 International Journal of Obesity (2013) 37, 350–356 & 2013 Macmillan Publishers Limited All rights reserved 0307-0565/13 www.nature.com/ijo