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TLR4 activation and IL-6-mediated cross talk between adipocytes and mononuclear cells synergistically stimulate MMP-1

Devadoss J Samuvel1, Junfei Jin, Kamala P Sundararaj

  • 1Ralph H. Johnson Veterans Affairs Medical Center, and Division of Endocrinology, Diabetes, and Medical Genetics, Department of Medicine, Medical University of South Carolina, 114 Doughty Street, Charleston, South Carolina 29403, USA.

Endocrinology
|September 29, 2011
PubMed

Insights

Obesity involves increased adipocyte-monocyte interaction. Activating Toll-like receptor 4 (TLR4) with adipocyte-derived IL-6 synergistically boosts matrix metalloproteinase-1 (MMP-1) production, potentially driving adipose tissue expansion.

Area of Science:

  • Adipose tissue biology
  • Immunology
  • Metabolic disease research

Background:

  • Obesity increases monocyte infiltration into adipose tissue, enhancing adipocyte-monocyte interactions.
  • Matrix metalloproteinases (MMPs) are crucial for adipose tissue development, but their production during adipocyte-monocyte crosstalk is poorly understood.
  • Toll-like receptor 4 (TLR4) activation is implicated in obesity-related inflammation and insulin resistance, yet its impact on MMP production in this context is unknown.

Purpose of the Study:

  • To investigate the combined effect of adipocyte-monocyte interaction and Toll-like receptor 4 (TLR4) activation on matrix metalloproteinase-1 (MMP-1) production.
  • To elucidate the underlying molecular mechanisms driving MMP-1 expression in this co-culture system.

Main Methods:

  • Adipocytes were co-cultured with U937 mononuclear cells using a Transwell system.
  • Toll-like receptor 4 (TLR4) was activated using lipopolysaccharide or palmitic acid.
  • Interleukin-6 (IL-6) and MMP-1 expression levels were analyzed.

Main Results:

  • Co-culture and TLR4 activation synergistically increased MMP-1 production.
  • Adipocyte-derived IL-6 and TLR4 activation worked together to stimulate MMP-1 expression in U937 cells.
  • This synergistic effect suggests a novel pathway for MMP-1 up-regulation in adipose tissue.

Conclusions:

  • A novel mechanism involving synergistic interaction between adipocyte-derived IL-6 and TLR4 activation enhances MMP-1 production by monocytes.
  • This pathway may contribute to adipose tissue development and the progression of obesity.
  • Understanding this interaction could offer new therapeutic targets for obesity-related metabolic dysfunction.

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