Fat metabolism in animals altered to prevent most common type of heart disease

In a series of experiments, described April 7 in the journal Circulation, the Johns Hopkins team says it identified and halted the action of a single molecular culprit responsible for a range of biological glitches that affect the body’s ability to properly use, transport and purge itself of cholesterol — the fatty substance that accumulates inside vessels and fuels heart disease.

The offender, the researchers say, is a fat-and-sugar molecule called glycosphingolipid, or GSL, which resides in the membranes of all cells, and is mostly known for regulating cell growth. Results of the experiments, the scientists say, reveal that this very same molecule also regulates the way the body handles cholesterol.

The Johns Hopkins team used an existing human-made compound called D-PDMP to block the synthesis of the GSL molecule, and by doing so, prevented the development of heart disease in mice and rabbits fed a high-fat, cholesterol-laden diet. The findings reveal that D-PDMP appears to work by interfering with a constellation of genetic pathways that regulate fat metabolism on multiple fronts — from the way cells derive and absorb cholesterol from food, to the way cholesterol is transported to tissues and organs and is then broken down by the liver and excreted from the body.

“Current cholesterol-lowering medications tackle the problem on a single front — either by blocking cholesterol synthesis or by preventing the body from absorbing too much of it,” says lead investigator Subroto Chatterjee, Ph.D., a cardio-metabolic expert at the Johns Hopkins Children’s Center. “But atherosclerosis is a multi-factorial problem that requires hitting the abnormal cholesterol cycle at many points. By inhibiting the synthesis of GSL, we believe we have achieved exactly that.”

Specifically, the experiments showed that treatment with D-PDMP led to: • a drop in the animals’ levels of so-called bad cholesterol or low-density lipoprotein, LDL; • a drop in oxidized LDL, a particularly virulent form of fat that forms when LDL encounters free radicals. Oxidized LDL easily sticks to the walls of blood vessels, where it ignites inflammation, damaging the vessel walls and promoting the growth of fatty plaque; • a surge in good cholesterol or high-density lipoprotein, HDL, known to counteract the effects of LDL by mopping it up; and • a significant drop in triglycerides, another type of plaque-building fat.

The treatment also prevented fatty plaque and calcium deposits from building up inside the animals’ vessels. These effects were observed in animals on a daily D-PDMP treatment even though they