PerspectiveOBESITY

Tighter lymphatic junctions prevent obesity

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Science  10 Aug 2018:
Vol. 361, Issue 6402, pp. 551-552
DOI: 10.1126/science.aau5583

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Summary

Dietary fats take a circuitous route from the intestine to the bloodstream, where they serve as nutrients or are stored in adipose tissue. Fats processed in the digestive tract are packaged by the intestinal epithelium into tiny lipid-protein particles called chylomicrons. Chylomicrons are taken up by lymphatic channels (lacteals) within villi that line the small intestine and are transported by lymphatic vessels to the blood circulation. How chylomicrons enter lacteals has long been a mystery, as the particles are too large to cross the endothelial cells that line lymphatics. Moreover, scattered openings observed in lacteals seemed too sparse to explain chylomicron entry, and evidence for vesicular transport was limited (1, 2). The discovery of specialized, discontinuous button-like junctions between lacteal endothelial cells raised another possibility (3). Button junctions have open regions and closed regions and are strikingly different from zipper junctions that tightly seal endothelial cells in blood vessels and collecting lymphatics. On page 599 of this issue, Zhang et al. (4) show that chylomicron entry is dependent on button junctions. Importantly, experimental manipulations that led to transformation of button junctions into zippers prevented chylomicron uptake and protected mice from developing obesity while on a high-fat diet.