Rethinking vascular wall: Periadventitial adipose tissue (tunica adiposa)

The prevailing response-to-injury hypothesis of Russell Ross states that atherosclerosis is an inflammatory intimai disease. Accordingly, intima-media thickness became an accepted measure of structural arterial remodeling and a strong predictor of atherosclerosis. However, it is unlikely that such one-direction road may solely travel the whole multiplex network like that of atherogenesis. A decade ago, we have proposed an interactive hypothesis ofatherogenesis, involving all structural components of the arterial wall including periadventitial adipose tissue (PAAT). As already alluded to, the arterial wall consists of three concentric tissue coats (tunicae): intima, media, and adventitia. In the present short review, we highlight accumulated data about PAAT, and conceptualize PAAT as the fourth coat of arterial wall, that is, tunica adiposa; in brief, adiposa, like intima, media, adventitia. Adiposa-derived adipokines - via paracrine way - may contribute to various vascular functions such as contraction-relaxation, smooth muscle cell growth, hemostasis, innervation, and inflammation. Altogether, the concept of tunica adiposa may contribute to further research in cardiovascular adipo-biology in health and disease. ©2010, Editrice Kurtis.