High levels of blood fat cause inflammation, damage kidneys and blood vessels

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Fat molecules interact with body cells and can mobilize the body's immune system to damaging effect, according to new research published in the journal Nature Immunology.

Viral and bacterial infections are not the only causes of inflammation of body tissue. It has been known for some time that certain fat molecules or lipids in the bloodstream can trigger an inflammatory response. Patients with higher levels of these fats in their blood have a significantly greater chance of dying early from kidney damage or vascular disease, researchers said.

Researchers led by Timo Speer, MD, PhD, of Saarland University in Saarbrücken, Germany, studied a specific group of lipids, triglycerides.

“We've been able to show that when these naturally occurring fats are present at elevated concentrations, they can alter our defense cells in such a way that the body reacts as if responding to a bacterial infection,” said Speer. “This leads to inflammation, which, if it becomes chronic, can damage the kidneys or cause atherosclerosis, the narrowing of arteries due to a buildup of deposits on the inner arterial wall. And atherosclerosis is one of the main causes of heart attacks and strokes.”

The large-scale study demonstrated that patients with elevated levels of triglycerides in their blood had a significantly higher mortality rate than comparison groups with a similar health history. Speer said they can now say that adopting a low-fat diet can significantly extend the life expectancy of high-risk patients, such as those with diabetes or those whose blood pressure is too high.

“As a result of biochemical changes, the triglycerides develop toxic properties that activate the body's innate immune system,” said Speer. “This initiates a series of self-destructive processes, including those in which the walls of the arteries are attacked, and the blood vessels become occluded, reducing blood flow.”

The study establishes a link between the chronic inflammation triggered by an elevated triglyceride concentration in the blood and secondary diseases such as kidney failure or heart attack.

“We hope that our results will help in developing new strategies for treating and preventing these life-threatening diseases,” said Speer.