Metagenomics, Lipoproteins, and Cardiovascular Risk

Triglyceride-rich lipoproteins—very low-density lipoproteins (VLDL) and chylomicrons—are considered atherogenic. The postprandial state, during which plasma levels of these lipoproteins are increased, is characterized by an inflammatory response that also involves endothelia. Free fatty acids released from chylomicrons and VLDL near the endothelium may be responsible for this. However, recent studies on mice and human subjects have revealed that intestinal absorption of dietary fat promotes absorption of bacterial lipopolysaccharides (LPS), which are atherogenic. Absorbed LPS is transported on chylomicrons, which suggests that LPS could contribute to postprandial inflammation. Recent work suggests that the intestinal microflora may influence atherosclerosis by affecting energy harvest from the diet. The novel link between intestinal absorption of fat and of LPS suggests that the microflora could also affect atherosclerosis by providing proinflammatory material to the bloodstream. Unraveling the chylomicron-associated LPS absorption mechanism and identification of micro-organisms providing the LPS may be beneficial for the prevention of atherosclerosis.