Gene Tied to Inflammatory Attack on Arteries

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Gene Tied to Inflammatory Attack on Arteries

December 31, 2003 02:04:25 PM PST , HealthDay

By Ed Edelson

HealthDay Reporter

WEDNESDAY, Dec. 31 (HealthDayNews) -- California researchers have

discovered a gene that can increase the risk of heart attack and stroke

by launching an inflammatory attack against blood vessels.

For people who carry the gene, the finding reinforces a standard

dietary recommendation for keeping arteries healthy: Eat more oily fish,

such as salmon.

That advice is aimed at reducing blood levels of one sort of fatty

molecule, low-density cholesterol. This time, the idea is to avoid foods

containing n-6 polyunsaturated fatty acids, a class of fats that set off

the inflammatory reaction. However, a different class of polyunsaturated

fatty acids -- designated n-3, which are found in fish -- suppress the

inflammatory response.

Inflammation has been big news in cardiovascular research

recently. Study after study has shown that high blood levels of

C-reactive protein, a marker of inflammation, are associated with

increased risk of artery damage. But until now, no one has known why the

inflammatory attack occurs.

" This is the first example of how a gene that causes inflammation

is involved in artery blockage, " says Hooman Allayee, a fellow in the

human genetics department of the University of California at Los Angeles

and leader of the team reporting the finding in the Jan. 1 issue of the

New England Journal of Medicine.

Allayee and his colleagues have found a fairly common form of the

gene for 5-lipoxygenase, a molecule involved in the body's defense

against injury, can be activated by fatty acids in the diet to attack

the arteries.

Inflammation is a basic defense mechanism, but it can often go

wrong, causing diseases such as rheumatoid arthritis and asthma,

explains study co-author H. Dwyer, a professor of preventive

medicine at the University of Southern California. In this case, the

gene causes the attack to be aimed at the arteries, he says.

A study of 470 healthy Los Angeles residents found that about 6

percent of them carry the potentially dangerous form of the gene, Dwyer

says. Detailed studies shown abnormal thickening of artery walls, a

warning sign of cardiovascular disease, in the people with that form of

the gene.

People who carry the dangerous version of the gene should avoid

foods containing two n-6 polyunsaturated fats, arachidonic acid and

linoleic acid, all of which stimulate the inflammatory activity, Dwyer

says. Organ meats -- liver, heart, giblets -- should be avoided because

they have high levels of arachidonic acid. Vegetable oils from corn and

soybeans should be avoided because they are rich in linoleic acid, he

says. Olive oil is preferable because it has a lot of n-3

polyunsaturated fatty acids, which prevent inflammation.

The gene " is more prevalent in people of non-European ancestry,

such as blacks and Asians, " Dwyer says. " About 10 to 20 percent of them

have this form of the gene. Specific dietary and pharmaceutical

intervention should be effective in this group. "

The variant form of the gene seems to make a normal process of

repairing injury to an artery become dangerous, Dwyer says. " If our

findings are confirmed to show that people carrying this genotype are at

increased risk, it won't be long until we have a routine clinical test

to detect it, " he says.

But these are " early days, " Dwyer adds. " We need a lot more

practical experience. "