Fig. 2

Response of visceral fat tissue to excess calories by adipocyte hypertrophy and hyperplasia. In response to high levels of circulating glucose, triglycerides, and the anabolic hormone insulin mature adipocytes take up increased amounts of nutrients and store excess energy as triglycerides in one large lipid droplet organelle. The cell size may increase 10–15-fold in diameter. Enlarged adipocytes secrete factors favoring angiogenesis and remodeling of the extracellular matrix and release of growth factors which is essential for mesenchymal stem cells, adipocyte progenitors, and preadipocytes to differentiate into lipid-storing mature adipocytes. In parallel, macrophages are stimulated to support angiogenesis and matrix remodeling. ATM, adipocyte tissue macrophages; TGs, triglycerides; Glc, glucose; ECM, extracellular matrix; Pro-inflamm., pro-inflammatory mediators