Microenvironment of Immune Cells Within the Visceral Adipose Tissue Sensu Lato vs. Epicardial Adipose Tissue: What Do We Know?

The chronic low-grade inflammation of the visceral adipose tissue is now fully established as one of the main contributors to metabolic disorders such as insulin resistance, subsequently leading to metabolic syndrome and other associated cardiometabolic pathologies. The orchestration of immune response and the "ratio of responsibility" of different immune cell populations have been studied extensively over the last few years within the visceral adipose tissue in general sense (sensu lato). However, it is essential to clearly distinguish different types of visceral fat distribution. Visceral adipose tissue is not only the classical omental or epididymal depot, but includes also specific type of fat in the close vicinity to the myocardium-the epicardial adipose tissue. Disruption of this type of fat during obesity was found to have a unique and direct influence over the cardiovascular disease development. Therefore, epicardial adipose tissue and other types of visceral adipose tissue depots should be studied separately. The purpose of this review is to explore the present knowledge about the morphology and dynamics of individual populations of immune cells within the visceral adipose tissue sensu lato in comparison to the knowledge regarding the epicardial adipose tissue specifically.