Figure 1.
Interactions between macrophages and preadipocytes/adipocytes in the adipose tissue. In the lean individual, the M2 (anti-inflammatory) macrophages are dispersed between the adipocytes. They keep adipose tissue homeostasis. The influx of lipids in a high-fat diet induces a switch of macrophages phenotype from M2 to the pro-inflammatory M1. In high-fat condition, macrophages form the crown-like structure, which surrounds adipocytes. Macrophages phagocyte dead cells and debris. A high-fat diet also induces the proliferation of pre-adipocytes through the activation of the Id3 factor and activates the synthesis of MCP-1. MCP-1 mediates chronic inflammation and recruits additional monocytes/macrophages to the adipose tissue. Id3, inhibitor of differentiation 3; MCP-1, monocyte chemoattractant protein-1.