Macrophage-adipocyte interaction: Marked interleukin-6 production by lipopolysaccharide

Akiko Yamashita, Yoshihiko Soga, Yoshihiro Iwamoto, Sayuri Yoshizawa, Hirotaka Iwata, Susumu Kokeguchi, Shogo Takashiba, Fusanori Nishimura

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52 Citations (Scopus)

Abstract

Objective: Recent studies suggested macrophages were integrated in adipose tissues, interacting with adipocytes, thereby exacerbating inflammatory responses. Persistent low-grade infection by gram-negative bacteria appears to promote atherogenesis. We hypothesized a ligand for toll-like receptor 4 (TLR4), bacterial lipopolysaccharide (LPS), would further exaggerate macrophage-adipocyte interaction. Research Methods and Procedures: RAW264.7 macrophage cell line and differentiated 3T3-L1 preadipocytes were co-cultured using transwell system. As a control, each cell was cultured independently. After incubation of the cells with or without Escherichia coli LPS, tumor necrosis factor (TNF)-α and interleukin (IL)-6 production was evaluated. Results: Co-culture of macrophages and adipocytes with low concentration of Escherichia coli LPS (1 ng/mL) markedly up-regulated IL-6 production (nearly 100-fold higher than that of adipocyte culture alone, p < 0.01), whereas TNF-α production was not significantly influenced. This increase was partially inhibited by anti-TNF-α neutralizing antibody. Recombinant TNF-α and LPS synergistically up-regulated IL-6 production in adipocytes. However, this increase did not reach the level of production observed in co-cultures stimulated with LPS. Discussion: A ligand for TLR-4 stimulates macrophages to produce TNF-α. TNF-α, thus produced, cooperatively up-regulates IL-6 production with other soluble factors secreted either from adipocytes or macrophages in these cells. Markedly up-regulated IL-6 would greatly influence the pathophysiology of diabetes and its vascular complications.

Original languageEnglish
Pages (from-to)2549-2552
Number of pages4
JournalObesity
Volume15
Issue number11
DOIs
Publication statusPublished - Nov 2007

All Science Journal Classification (ASJC) codes

  • Medicine (miscellaneous)
  • Endocrinology, Diabetes and Metabolism
  • Endocrinology
  • Nutrition and Dietetics

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    Yamashita, A., Soga, Y., Iwamoto, Y., Yoshizawa, S., Iwata, H., Kokeguchi, S., Takashiba, S., & Nishimura, F. (2007). Macrophage-adipocyte interaction: Marked interleukin-6 production by lipopolysaccharide. Obesity, 15(11), 2549-2552. https://doi.org/10.1038/oby.2007.305