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rheumatoid arthritis



Study may force re-think on rheumatoid arthritis

By Maggie Fox, Health and Science Correspondent

WASHINGTON, Aug 1 (Reuters) - The idea that patients with rheumatoid arthritis have overactive immune systems could be completely backward, researchers said on Tuesday -- something that would force a re-think of how the condition is treated.

A team at the Mayo Clinic in Rochester, Minnesota, found that patients with rheumatoid arthritis in fact have damaged immune systems.

``What this study has shown for the first time is that patients with rheumatoid arthritis have prematurely aged immune systems,'' Dr. Cornelia Weyand, a rheumatologist who led the study, said in a statement.

``Until now we have thought that these patients had overactive immune systems, which is why we have aggressively treated the symptoms of rheumatoid arthritis with medications that suppress the immune system,'' said Weyand, whose findings were published in the Proceedings of the National Academy of Sciences.

``While this practice offers relief of the painful symptoms, it also puts patients at greater risk for infections and cardiovascular disease -- the two leading causes of death among these patients.''

Scientists estimate about 2.1 million Americans, nearly 1 percent of the population, have rheumatoid arthritis -- most of them women.

The disease is marked by pain, swelling, stiffness, and loss of function in the joints, and patients may also complain of fatigue, occasional fever and a general malaise.

It is classified as an autoimmune disease -- one in which the immune system mistakenly attacks healthy tissue. In this case it is the joints.

Weyand and colleagues studied the immune systems of 51 patients with rheumatoid arthritis and compared them to 47 people of similar age who did not have the condition.

They found that the T-cells -- the immune cells that are programmed to recognise and attack invaders such as bacteria and viruses -- were worn out.

One of the strengths of the human immune system is the large repertoire of so-called memory T-cells, which can recognise hundreds of different strains of cold viruses, streptococcal bacteria, and thousands of other microbes that would make us sick daily were it not for the T-cells.

As people age, this repertoire gets smaller, which is one reason why older people are more at risk from diseases such as influenza.


Weyand's team found that young rheumatoid arthritis patients had many fewer different T-cells than they should have. Patients 20 to 30 years old had a collection of T-cells that looked like they belonged to 50- to 60-year olds.

And the chromosomes in the cells, which are the structures that carry the genetic material, were frayed. Chromosomes are capped with parts called telomeres, which get a little worn with each cell division. Weyand's team said the telomeres on the T-cells were worn away.

She said it will take more research to show which came first, the rheumatoid arthritis or the exhausted immune system. ``When we learn this, we can determine if regenerating the immune system will prevent or alleviate problems associated with rheumatoid arthritis,'' she said.

``This study shows that physicians need to evaluate the status of a patient's immune system before choosing a medication and dosage. By doing this, we can suppress the immune system as little as possible and protect the patient's ability to respond to infections as much as possible.''

Another study in the same journal offered a potential new treatment for rheumatoid arthritis.

Marc Feldmann at the Kennedy Institute of Rheumatology in London and colleagues found that a natural constituent of marijuana, cannabidiol, helped mice they had caused to have a disease resembling rheumatoid arthritis.

Working with a team in Israel, Feldmann's team said they found cannabidiol blocked the progression of disease by suppressing both the immune system and the body's inflammatory response.

13:28 08-01-00

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