Your snoring might sound like a tractor revving up, but it could actually indicate that the cells in your veins are breaking down.
Scientists have long known that obstructive sleep apnea, a disorder that often causes snoring, can increase your risk of cardiovascular diseases, but they didn’t know exactly why. Now, a team of doctors at Columbia University has pinpointed a Rube Goldberg-like chain of events that explains how this damage might occur, and found that some commonly prescribed anticholesterol drugs can prevent it.
“We were prepared for anything and this just came up,” said Dr. Sanja Jelic, an associate professor at Columbia and one of the authors of the study. “It’s never been described in sleep apnea.”
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During sleep, the muscles in a person’s airway relax. If those relaxed muscles flop into the path of incoming air, as they do in sleep apnea, they can deprive the body of oxygen for as long as 40 seconds.
The research team at Columbia wanted to figure out how that interrupted breathing was affecting the cells that line blood vessels, which is often where cardiovascular damage begins. They extracted these cells from the arms of 76 patients with obstructive sleep apnea and 52 others who didn’t have the disorder.
They found that those with sleep apnea had a much higher level of a protein called CD59. This butterfly-shaped protein guards cells from attack by the body’s own immune system. However, on closer inspection, researchers discovered that the CD59 of people with sleep apnea had been pulled inside the cell, instead of guarding the cell’s surface, leaving the cell vulnerable to attacks from the immune system.
These damaged cells, in turn, would be more likely to obstruct blood flow — the first such cellular explanation of how apnea may cause heart problems.
But one group of snorers didn’t have these abnormal CD59 effects. Five apnea patients who happened to be taking statins — drugs that lower cholesterol — had cells that looked just as healthy as the cells of people without sleep apnea. That suggests that statins could help protect apnea patients from cardiovascular trouble. The results were published Wednesday in Science Translational Medicine.
“This is a great start to try to understand the damage that sleep apnea does,” said Dr. Shalini Paruthi, a sleep medicine expert at Saint Louis University, who was not involved in the study.
“The data that we have here would surely point to important new clinical trials,” said Dr. Alfred Bove, past president of the American College of Cardiology and an emeritus professor of medicine at Temple University. But doctors are not going to be prescribing statins just for sleep apnea anytime soon, he said.
It isn’t exactly clear why the cholesterol-lowering medication allows CD59 to function normally. Jelic suggested that cholesterol may be what is pulling the protein inside the cell, and that by reducing the amount of cholesterol with a statin, CD59 stays put.
Bove isn’t so sure about that hypothesis. “It’s a chicken-and-egg question,” he said.
Paruthi added that this damage to blood vessels is just one of the risks posed by sleep apnea. She said that the disorder’s interruption of a person’s sleep can lead to drowsiness at the wheel and car crashes. “We run into the myth that snoring’s OK,” she said. “But snoring’s not OK. It might be the sign of something very dangerous.”