Link between Adipose Tissue Angiogenesis and Fat Accumulation in Severely Obese Subjects

Abstract

White adipose tissue (WAT) can rapidly expand or regress under different nutritional conditions. The role of angiogenesis in the expandability of human adipose tissue is established. However, whether sc and omental WAT (scWAT and oWAT) angiogenesis could influence fat distribution and metabolic diseases is not known. The aim of this study was to analyze whether the capacity of angiogenesis in scWAT and oWAT correlates with fat accumulation and fat loss, fat distribution, adipocyte hypertrophy, and metabolic disorders in obese subjects. Samples of scWAT and oWAT were obtained during bariatric surgery in 29 obese nondiabetic subjects. Vascular density and inflammatory infiltrate were analyzed by immunohistochemistry, and expression of angiogenic genes was analyzed by quantitative PCR. These parameters were correlated with anthropometric and metabolic parameters. Vascular density of scWAT correlated positively with body mass index, whereas vascular density of the oWAT correlated with waist circumference. There was no correlation of markers of angiogenesis and metabolic disorders. The number of vessels per adipocyte and the expression level of receptor 2 of vascular endothelial growth factor correlated with adipocyte area in scWAT and oWAT. Finally, weight loss after bariatric surgery correlated negatively with adipocyte hypertrophy and vascular density and positively with inflammation and angiogenesis of WAT. Angiogenesis may influence WAT expansion and plasticity but does not appear to be involved in the development of insulin resistance in subjects with severe obesity.