Abstract P496: Exosomes From Brown Adipose Tissue Contain Cardiac Gene-regulatory Elements

Abstract

Exosomes, extracellular vesicles <150 nm, are vehicles for transporting information (i.e., cargo) allowing tissue to tissue communication. Depending on the cargo, exosomes can have beneficial or detrimental effects. Brown Adipose Tissue (BAT) is a thermogenic organ that modulates metabolism. BAT is also an endocrine organ affecting function of various distant tissue. We have recently shown that BAT is an important modulator of the healthy and diseased heart. Adipose tissue is a large source of circulating exosomes, but the effects of BAT and changing BAT activity on circulating exosome number and cargo are unknown. Identifying the role of BAT in modulating exosome number and cargo is important since the myocardium is highly responsive to exosomes. We used various known approaches that increase BAT activity (cold exposure, BATcold) or decrease BAT activity (BAT removal (BATless), obesity (HFD), aging (old)) and examined the number and content of circulating exosomes. Upon BAT activation via cold exposure, there was a large increase in circulating exosome numbers (see figure). All approaches that results in decreased BAT activity resulted in a decrease in circulating exosome numbers (see figure). We further examined the role of changing BAT activity on the content (i.e., cargo) of the exosomes, specifically focusing on miRNA. Interestingly, changing BAT activity resulted in large changes to the content of the exosomes, with some miRNA increasing levels and other miRNA decreasing levels. Some of these identified miRNA have been shown to exert beneficial effects on the heart and many miRNA having no defined effect on cardiac function. We believe that these BAT activated exosomes have the combination and proportion of circulatory miRNA necessary to enhance and maintain heart function. There is a great need for new strategies and approaches for treatment of cardiovascular disease (CVD). Our data suggest that a novel treatment strategy for CVD can be derived from BAT exosomes.