Adipose Tissue Oxygenation in Obesity: A Matter of Cardiovascular Risk?

Obesity, a chronic low-grade inflammation disorder characterized by an expansion in adipose tissue mass, is rapidly expanding worldwide leading to an increase in the incidence of comorbidities such as insulin resistance, type 2 diabetes and cardiovascular diseases. This has led to a renewed interest in the adipose tissue function, historically considered as a passive fat storage. It is now well established that adipose tissue is an organ with an active role in production and release of a variety of molecules called adipocytokines. Dysregulated production of adipocytokines seems to be responsible for the pathogenesis of insulin resistance and type 2 diabetes; however, the mechanisms are still unclear. Hypoxia, that occurs when adipocytes expand in obesity, has been proposed as a possible cause of adipose tissue inflammation. On the other hand, recent studies have shown that adipose tissue oxygen tension was actually higher (hyperoxia) than normal and associated with insulin resistance in obesity, despite a reduction in blood flow. This might be explained by the role of mitochondrial oxygen consumption. Hence, further studies are needed to understand the role of adipose tissue oxygenation and perfusion in obesity to assess pathophysiology and novel opportunities for treating the diseases.