Monocyte Chemoattractant Protein-1 Release Is Higher in Visceral than Subcutaneous Human Adipose Tissue (AT): Implication of Macrophages Resident in the AT

Human adipose tissue (AT) produces several adipokines including monocyte chemoattractant protein (MCP)-1, involved in the pathogenesis of atherosclerosis. Objective: Human AT cultures, isolated adipocytes, and stromal-vascular cells were used to investigate the relationship among AT-resident macrophages, MCP-1, and adiposity and the regulation of MCP-1. Results: mRNA levels of specific macrophage markers (CD68 and CD14) are correlated with adiposity in sc AT and visceral AT (P < 0.05). MCP-1 production is higher in stromal-vascular cells vs. adipocytes (P < 0.01) and correlates with macrophage markers in both AT compartments (P < 0.05). MCP-1 release is higher in obese subjects (P < 0.05) and in VAT (P < 0.01), but after adjusting for AT-resident macrophages, the differences disappear. MCP-1 is stimulated by IL-1β, TNF-α, IL-8, IL-4, and IL-6 + IL-6-soluble receptor and is decreased by dexamethasone, IL-10, metformin, and thiazolidinediones. Discussion: MCP-1 is correlated with specific macrophage markers, adiposity, and AT localization, but the relationship seems to be related to the number of AT-resident macrophages. Despite this, MCP-1 may be involved in obesity-related health complications, and the decrease of MCP-1 by metformin and thiazolidinediones suggests that these antidiabetic compounds have antiinflammatory properties improving the low-grade inflammatory state observed in obesity.