Human adipocyte extracellular vesicles in reciprocal signaling between adipocytes and macrophages

Obesity (Silver Spring). 2014 May;22(5):1296-308. doi: 10.1002/oby.20679. Epub 2014 Jan 9.


Objective: Extracellular vesicles (EVs) released by human adipocytes or adipose tissue (AT)-explants play a role in the paracrine interaction between adipocytes and macrophages, a key mechanism in AT inflammation, leading to metabolic complications like insulin resistance (IR) were determined.

Methods: EVs released from in vitro differentiated adipocytes and AT-explants ex vivo were characterized by electron microscopy, Western blot, multiplex adipokine-profiling, and quantified by flow cytometry. Primary monocytes were stimulated with EVs from adipocytes, subcutaneous (SCAT) or omental-derived AT (OAT), and phenotyped. Macrophage supernatant was subsequently used to assess the effect on insulin signaling in adipocytes.

Results: Adipocyte and AT-derived EVs differentiated monocytes into macrophages characteristic of human adipose tissue macrophages (ATM), defined by release of both pro- and anti-inflammatory cytokines. The adiponectin-positive subset of AT-derived EVs, presumably representing adipocyte-derived EVs, induced a more pronounced ATM-phenotype than the adiponectin-negative AT-EVs. This effect was more evident for OAT-EVs versus SCAT-EVs. Furthermore, supernatant of macrophages pre-stimulated with AT-EVs interfered with insulin signaling in human adipocytes. Finally, the number of OAT-derived EVs correlated positively with patients HOMA-IR.

Conclusions: A possible role for human AT-EVs in a reciprocal pro-inflammatory loop between adipocytes and macrophages, with the potential to aggravate local and systemic IR was demonstrated.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipocytes / ultrastructure*
  • Adipokines / metabolism
  • Adiponectin / metabolism
  • Adipose Tissue / metabolism
  • Cell Communication*
  • Cell Differentiation
  • Cells, Cultured
  • Cytokines / metabolism
  • Humans
  • Immunologic Factors / pharmacology
  • Inflammation / metabolism
  • Insulin / metabolism
  • Insulin Resistance
  • Macrophages / metabolism*
  • Monocytes / cytology
  • Monocytes / metabolism
  • Obesity / metabolism
  • Signal Transduction


  • Adipokines
  • Adiponectin
  • Cytokines
  • Immunologic Factors
  • Insulin