Cancer Virus Now Tied to Deadly Lung Ailment

Herpesvirus found in primary pulmonary hypertension

WEDNESDAY, Sept. 17, 2003 (HealthDayNews) -- A virus that causes a form of skin cancer, Kaposi's sarcoma, has been found in patients with a rare and deadly lung condition, researchers report.

If the finding is confirmed, it will be a first clue to the cause of the condition, known as primary pulmonary hypertension.

Pulmonary hypertension is abnormally high blood pressure in the lung arteries, which can ultimately cause heart failure. Most cases of pulmonary hypertension are labeled "secondary," meaning they are caused by another breathing disorder, such as bronchitis.

Primary pulmonary hypertension, in which the cause is unknown, occurs in only one to two of every 1 million Americans. With careful treatment, says the Pulmonary Hypertension Association, "some patients have been able to manage the disorder for 15 or 20 years or even longer."

Now a group led by Dr. Norbert F. Voelkel of the University of Colorado Health Sciences Center reports in the Sept. 18 issue of the New England Journal of Medicine that evidence of infection with human herpesvirus-8 (HHV-8), which is known to cause Kaposi's sarcoma and several forms of blood cancers, has been detected in 10 of 16 patients with primary pulmonary hypertension.

It is an important finding because "if it does cause the condition, that would help find treatments for the disease," says Dr. Ethel Cesarman, an associate professor of pathology at Cornell University's Weill Medical College, who wrote an accompanying editorial. "And you can have other defenses, such as vaccinations."

The finding holds hope for patients because "it provides a conceptual model of what is going on in the lungs," says Voelkel, a professor of medicine at Colorado. Until now, with no apparent cause evident, treatment has consisted of continuous injusion of artery-widening medication, he says.

"This is expensive, and it has not generated a cure," Voelkel says. At best, It has lengthened survival time to four or five years. Now that the condition can be regarded as "a form of malignancy," new approaches are possible, he says.

One reason why the researchers looked for HHV-8 in these patients is that the virus often accompanies HIV, the virus that causes AIDS, the journal report says. In Africa, where HIV infection is rife, HHV-8 Kaposi's sarcoma is "the most common cancer in children," Cesarman says.

Tests were done on cells from patients with either primary or secondary pulmonary hypertension, the researchers report. Immune system antibodies generated by exposure to HHV-8 were found in 10 of the patients with primary hypertension, but none were found in the patients with the secondary form of the disorder.

"The paper suggests that the virus causes it, but it requires confirmation," Cesarman says, and the researchers acknowledge that "we cannot conclude that infection alone causes this condition." One possibility is that having pulmonary hypertension increases the risk of HHV-8 infection, they say.

But they also report that tissue samples from primary pulmonary hypertension patients and those with Kaposi's sarcoma look alike, with narrow, slit-like spaces between cells and sheets of cells that produce VEGF, a growth factor that causes overproduction of skin cells and cells of the endothelium, the tissue that lines the lung arteries.

That resemblance leads to a logical theory of how the HHV-8 virus is involved in development of pulmonary hypertension. When someone with an underlying genetic characteristic, as yet unidentified, is infected with HHV-8, the result can be uncontrolled growth of the cells of the lung artery endothelium that chokes blood flow, causing the severe rise in blood pressure that creates the lung problem, the report says. That mimics the presence of HHV-8 virus in the skin that causes the uncontrolled cell growth of Kaposi's sarcoma, it adds.

More information

You can learn about the disorder from the Pulmonary Hypertension Association or the American Heart Association.

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