Researchers at the University of Ottawa Heart Institute say that autophagy, an innate function that allows cells to consume a portion of themselves, also moves and exports cholesterol in artery vessels.
Autophagy, which means "self-eating" in Greek, helps our bodies' starving cells destroy dysfunctional molecules and recycle the components into other nutrients we may need more.
The process has been well-documented by the medical community, but lead researcher and biochemist Yves Marcel says his team is the first to link autophagy to how some cholesterol is moved from artery walls.
"This is very significant for those who have a buildup of cholesterol because this is a way to export it from their bodies," Marcel, director of the university's HDL Biology Laboratory, said.
Cholesterol accumulation in artery walls can lead to atherosclerosis — the narrowing of the arteries — which in turn leads to blocking blood flow to the heart. The condition can cause heart attacks and strokes.
Marcel said his team's findings could aid in the development of new drugs that can increase the removal of cholesterol from our bodies and halt the progression of heart disease, noting that there is an "urgent need" to understand how the buildup of cholesterol can be reversed.
After testing with mice, results showed that the autophagy pathway is responsible for 50 per cent of the body's removal of cholesterol from the arteries into the blood and then to the liver for disposal, Marcel explained.
Our bodies also naturally remove cholesterol using neutral enzymes that carry the fat lipids away, he said.
But results, published in the journal Cell Metabolism, showed that rodents who already had cholesterol buildup in severe amounts — enough to see the deposits in the artery walls through imaging — had stalled the process.
"As cholesterol increases, it seems, unfortunately, that this passageway is downgraded maybe explaining why there is accumulation," Marcel said.
Although it's not confirmed, Marcel said people with coronary artery disease likely have an impaired ability to clear cholesterol in the area through the autophagy pathway.
Marcel plans to research how much cholesterol bodies can remove through autophagy and why some patients could face limitations in the process.
About 40 per cent of Canadians have high blood cholesterol levels and as many as 10 million people have cholesterol levels higher than their recommended target based on risk of heart disease or stroke, according to the Canadian Heart and Stroke Foundation.
Heart disease and stroke are two of the three leading causes of death in the country, the organization says.