Endothelial and Perivascular Adipose Tissue Abnormalities in Obesity-Related Vascular Dysfunction: Novel Targets for Treatment
The heavy impact of obesity on the development and progression of cardiovascular disease has sparked sustained efforts to uncover the mechanisms linking excess adiposity to vascular dysfunction. In addition to its well-established role in maintaining vascular homeostasis, the endothelium has been increasingly recognized as a key player in modulating healthy adipose tissue expansion in response to excess calories by providing adipocyte precursors and driving angiogenesis. When this increased storage need is unmet, excessive deposition of fat occurs at ectopic locations, including perivascular adipose tissue (PVAT). PVAT is in intimate contact with the vessel wall, hence affecting vascular function and structure. In lean individuals, PVAT exerts anticontractile and anti-inflammatory activities to protect the vasculature. In obesity, instead, these beneficial properties are lost and PVAT releases inflammatory mediators, promotes oxidative stress, and contributes to vascular dysfunction. The underlying mechanisms elicited by these outside-in signals include resistance to the vasodilator actions of insulin and activation of endothelin (ET)-1-mediated vasoconstriction. A number of adipokines and gut hormones, which are important modulators of food intake, energy balance, glucose and lipid metabolism, insulin sensitivity, and inflammation, have also positive vascular actions. This feature makes them promising tools for targeting both the metabolic and cardiovascular complications of obesity, a view supported by recent large-scale clinical trials indicating that novel drugs for type 2 diabetes with cardiovascular potential may translate into clinically significant benefits. There is, therefore, real hope that unleashing the power of fat- and gut-derived substances might provide effective dual-action therapies for obesity and its complications.