RESEARCH - Immune cells from patients with RA have prematurely aged chromosomes

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Immune Cells From Patients With Rheumatoid Arthritis Have Prematurely

Aged Chromosomes

MedicalNewsToday.com

Article Date: 05 Mar 2009 - 4:00 PST

Telomeres, structures that cap the ends of cells' chromosomes, grow

shorter with each round of cell division unless a specialized enzyme

replenishes them. Maintaining telomeres is thought to be important for

healthy aging and cancer prevention.

By this measure, T cells, or white blood cells, from patients with the

autoimmune disease rheumatoid arthritis are worn out and prematurely

aged, scientists at Emory University School of Medicine have

discovered.

Compared with cells from healthy people, T cells from patients with

rheumatoid arthritis have trouble turning on the enzyme that

replenishes telomeres, they found. Reversing this defect could

possibly help people prone to the disease maintain a balanced immune

system.

The results are published online this week in Proceedings of the

National Academy of Sciences.

In rheumatoid arthritis, T cells are chronically over-stimulated,

invading the tissue of the joints and causing painful inflammation.

This derangement can be seen as a result of the loss of the immune

system's ability to discriminate friend from foe, says senior author

Cornelia Weyand, MD, PhD, co-director of the Kathleen B. and Mason I.

Lowance Center for Human Immunology at Emory University.

In childhood, new T cells are continually produced in the thymus, she

says. But after about age 40, the thymus " involutes " - or shrinks and

ceases to function. After that, the immune system has to make do with

the pool of T cells it already has.

" What we see in rheumatoid arthritis is an aged and more restricted T

cell repertoire, " she says. " This biases the immune system toward

autoimmunity. "

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