Pro-inflammatory delipidizing cytokines reduce adiponectin secretion from human adipocytes without affecting adiponectin oligomerization

J Endocrinol. 2007 Feb;192(2):289-99. doi: 10.1677/JOE-06-0047.

Abstract

Adiponectin and, especially, its oligomeric complex composition have been suggested to be critical in determining insulin sensitivity. Pro-inflammatory cytokines play an important role in the development of insulin resistance in obesity and associated diseases. Therefore, we investigated the effect of long-term exposure of tumour necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-1beta, and interferon (IFN)-gamma on total insulin-sensitizing adiponectin secretion and adiponectin complex formation from human adipocytes. In parallel, adipocyte delipidation and leptin production levels were monitored. The present study demonstrates that TNF-alpha, IL-1beta, and IFN-gamma dose and time dependently suppressed total adiponectin secretion within 7 days (60, 70, and 35% reduction respectively). IL-6 was also able to reduce (50%) adiponectin production, although only in combination with exogenous soluble IL-6 receptors (sIL-6R). However, the oligomeric distribution (high, middle, and low molecular weight (HMW) complexes) of secreted adiponectin was not altered by any of these cytokines. All studied pro-inflammatory cytokines resulted in delipidation and reduction of lipid-laden adipocyte numbers. Despite this reduction of lipid-laden adipocytes, TNF-alpha, IL-6/sIL-6R, and IL-1beta stimulated leptin release. Our data indicate that (i) long-term pro-inflammatory cytokine exposure downregulates total adiponectin secretion from delipidizing adipocytes and (ii) pro-inflammatory cytokines are not important regulators of adipocyte-derived adiponectin oligomerization. Hence, their individual contribution to low expression of HMW adiponectin found in insulin-resistant conditions seems unlikely. Furthermore, delipidizing adipocytes and preadipocytes are active leptin producers when stimulated by TNF-alpha, IL-6/sIL-6R, and IL-1beta.

MeSH terms

  • Adipocytes / drug effects
  • Adipocytes / metabolism*
  • Adiponectin / metabolism*
  • Adult
  • Analysis of Variance
  • Azo Compounds
  • Cell Proliferation
  • Cells, Cultured
  • Coloring Agents
  • Cytokines / pharmacology*
  • Depression, Chemical
  • Dose-Response Relationship, Drug
  • Enzyme-Linked Immunosorbent Assay / methods
  • Female
  • Humans
  • Insulin Resistance
  • Interferon-gamma / pharmacology
  • Interleukin-1beta / pharmacology
  • Interleukin-6 / pharmacology
  • Leptin / metabolism
  • Lipid Metabolism
  • Middle Aged
  • Protein Isoforms / metabolism
  • Receptors, Interleukin-6 / metabolism
  • Subcutaneous Fat
  • Time Factors
  • Tumor Necrosis Factor-alpha / pharmacology

Substances

  • Adiponectin
  • Azo Compounds
  • Coloring Agents
  • Cytokines
  • Interleukin-1beta
  • Interleukin-6
  • Leptin
  • Protein Isoforms
  • Receptors, Interleukin-6
  • Tumor Necrosis Factor-alpha
  • Interferon-gamma
  • oil red O