A paracrine loop between adipocytes and macrophages aggravates inflammatory changes: Role of free fatty acids and tumor necrosis factor α

Takayoshi Suganami, Junko Nishida, Yoshihiro Ogawa

Research output: Contribution to journalArticle

726 Citations (Scopus)

Abstract

Objective - Weight gain is associated with infiltration of fat by macrophages, suggesting that they are an important source of inflammation in obese adipose tissue. Here we developed an in vitro coculture system composed of adipocytes and macrophages and examined the molecular mechanism whereby these cells communicate. Methods and Results - Coculture of differentiated 3T3-L1 adipocytes and macrophage cell line RAW264 results in the marked upregulation of proinflammatory cytokines, such as tumor necrosis factor α(TNF-α), and the downregulation of the antiinflammatory cytokine adiponectin. Such inflammatory changes are induced by the coculture without direct contact, suggesting the role of soluble factors. A neutralizing antibody to TNF-α, which occurs mostly in macrophages, inhibits the inflammatory changes in 3T3-L1, suggesting that TNF-α is a major macrophage-derived mediator of inflammation in adipocytes. Conversely, free fatty acids (FFAs) may be important adipocyte-derived mediators of inflammation in macrophages, because the production of TNF-α in RAW264 is markedly increased by palmitate, a major FFA released from 3T3-L1. The inflammatory changes in the coculture are augmented by use of either, hypertrophied 3T3-L1 or adipose stromal vascular fraction obtained from obese ob/ob mice. Conclusions - We postulate that a paracrine loop involving FFAs and TNF-α between adipocytes and macrophages establishes a vicious cycle that aggravates inflammatory changes in the adipose tissue.

Original languageEnglish
Pages (from-to)2062-2068
Number of pages7
JournalArteriosclerosis, thrombosis, and vascular biology
Volume25
Issue number10
DOIs
Publication statusPublished - Oct 1 2005
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Cardiology and Cardiovascular Medicine

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