Perivascular adipose tissue, inflammation and vascular dysfunction in obesity

Adipocytes are no longer considered just as cells related to storage of energy and thermoregulation. Now we know that they release a huge number of paracrine and endocrine biologically active molecules. This is also the case for perivascular adipose tissue (PVAT) that surrounds almost all blood vessels in the organism. PVAT secretes the so-called adipo(cyto)kines that, because of its proximity, can easily influence vascular smooth muscle cells. The role of PVAT on vascular function can be both protective and deleterious. Normal healthy PVAT, as present in lean subjects, helps to keep the blood vessels dilated as its presence diminishes the effect of vasocontractile agents. Obesity is associated with an increased mass in PVAT. Excessive adipocyte hypertrophy may result in "adiposopathy" in which PVAT attracts macrophages and becomes a more inflammatory phenotype. This leads to a change in profile of the released adipo(cyto)kines, resulting in a decreased vasorelaxing effect of PVAT, which may be linked to obesity-induced hypertension. It also results in smooth muscle cell migration and proliferation and the development of atherosclerotic lesions. The increased knowledge of PVAT function brings up new targets that can be useful to develop novel therapeutic and preventive strategies for obesity-related cardiovascular diseases. This mini-review presents a general overview of the actual knowledge on the role of PVAT on vascular function and dysfunction in obesity.