Extracts from the Root of Platycodon grandiflorum Modulate Induction of Inflammatory Changes in Coculture of Adipocytes and Macrophages

Abstract

Obesity changes the morphology and composition of adipose tissue, leading to changes in production and secretion of the several proinflammatory mediators. This study aims to obtain in vitro evidences that extracts from the root of Platycodon grandiflorum (PGE) can inhibit inflammatory responses in obesity. We investigated the effect of PGE on the production of proinflammatory mediators in lipopolysaccharide (LPS)-stimulated macrophages and in the interaction between adipocytes and macrophages. At first, to determine whether PGE suppresses proinflammatory cytokine production in macrophages, RAW 264.7 macrophages were stimulated with LPS in the presence or absence of PGE for 24 h. PGE significantly inhibited the production of LPS-induced proinflammatory mediators as TNF-α, NO, and MCP-1 in the cells. We next examined the effect of PGE on proinflammatory mediators in coculture of adipocytes and macrophages. RAW 264.7 cells and hypertrophied 3T3-L1 cells were incubated in serum-free DMEM medium for 24 h. Then, PGE was added to the coculture at various concentrations for 24 h. The PGE treatment significantly decreased production of proinflammatory mediators in the cocultured cells. However, PGE enhanced anti-inflammatory mediator such as adiponectin expression. These data demonstrated that PGE may suppress the inflammatory responses of the adipose tissue in obesity.